U.S. patent application number 10/486330 was filed with the patent office on 2005-06-09 for method of controlling motor-driven washing machine and control system for the same.
Invention is credited to Bang, Jong Chul, Cho, In Haeng, Hong, Kwon Ki, Kim, Jong Ho, Koo, Bon Kwon, Lee, Woon Yong, Lyu, Jae Cheol, Oh, Min Jin, Son, Kweon.
Application Number | 20050120492 10/486330 |
Document ID | / |
Family ID | 29554640 |
Filed Date | 2005-06-09 |
United States Patent
Application |
20050120492 |
Kind Code |
A1 |
Koo, Bon Kwon ; et
al. |
June 9, 2005 |
Method of controlling motor-driven washing machine and control
system for the same
Abstract
A method of controlling a motor-driven washing machine and a
control system that controls a motor or any other components of the
washing machine are disclosed. The method includes the steps of
generating an interruption command for braking a motor in motion
during a wash cycle, applying a phase-reversed voltage to a voltage
input terminal of the motor in motion, and electrically shorting
the input terminal of the motor for a predetermined period of time
if a second phase-reversed voltage generated by the motor is higher
than or equal to a critical voltage level. Using such method, a
motor-clutch mechanism is prevented front generating a noise and
from being damaged during a wash cycle.
Inventors: |
Koo, Bon Kwon; (Seoul,
KR) ; Hong, Kwon Ki; (Kyongsangnam-do, KR) ;
Lyu, Jae Cheol; (Kyongsangnam-do, KR) ; Lee, Woon
Yong; (Gwangju-gwangyok-shi, KR) ; Bang, Jong
Chul; (Kyongsangnam-do, KR) ; Oh, Min Jin;
(Kyongsangnam-do, KR) ; Son, Kweon;
(Gyeongsangnam-do, KR) ; Kim, Jong Ho;
(Gyeongsangnam-do, KR) ; Cho, In Haeng;
(Kyongsangnam-do, KR) |
Correspondence
Address: |
MCKENNA LONG & ALDRIDGE LLP
1900 K STREET, NW
WASHINGTON
DC
20006
US
|
Family ID: |
29554640 |
Appl. No.: |
10/486330 |
Filed: |
January 14, 2005 |
PCT Filed: |
May 15, 2003 |
PCT NO: |
PCT/KR03/00960 |
Current U.S.
Class: |
8/159 ; 68/12.02;
68/12.16; 68/12.24; 8/158 |
Current CPC
Class: |
D06F 2105/48 20200201;
D06F 37/304 20130101; H02P 3/22 20130101; Y02B 40/00 20130101; D06F
2204/065 20130101; D06F 2202/065 20130101; D06F 34/08 20200201;
D06F 33/47 20200201; D06F 2103/24 20200201 |
Class at
Publication: |
008/159 ;
008/158; 068/012.02; 068/012.16; 068/012.24 |
International
Class: |
D06F 033/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2002 |
KR |
10-2002-0026886 |
May 16, 2002 |
KR |
10-2002-0027127 |
May 16, 2002 |
KR |
10-2002-0027132 |
Jul 11, 2002 |
KR |
10-2002-0040211 |
Jul 11, 2002 |
KR |
10-2002-0040292 |
Jul 29, 2002 |
KR |
10-2002-0044687 |
Nov 25, 2002 |
KR |
10-2002-0073580 |
Nov 26, 2002 |
KR |
10-2002-0073898 |
Nov 26, 2002 |
KR |
10-2002-0074052 |
Nov 26, 2002 |
KR |
10-2002-0074054 |
Claims
What is claimed is:
1. A method of controlling a motor-driven washing machine, the
method comprising the steps of: generating an interruption command
for braking a motor in motion during a wash cycle; applying a first
phase-reversed voltage to a voltage input terminal of the motor in
motion, the first phase-reversed voltage corresponding to a first
current speed of the motor; and electrically shorting the voltage
input terminal of the motor for a predetermined period of time if a
second phase-reversed voltage is higher than or equal to a critical
voltage level, the second phase-reversed voltage corresponding to a
second current speed of the motor.
2. The method of claim 1, wherein the interruption command is
generated when a user cuts off a power supply to the washing
machine, manually touches a key control panel, or opens a washer
door of the washing machine during the wash cycle.
3. The method of claim 1, wherein the critical voltage level is
predetermined such that the motor generates a brake noise if the
second phase-reversed voltage is higher than or equal to the
critical voltage level and is applied to the voltage input terminal
of the motor.
4. The method of claim 1, further comprising the step of applying a
third phase-reversed voltage to the voltage input terminal of the
motor in motion if the second current speed of the motor is lower
than the critical voltage value, wherein the third phase-reversed
voltage corresponds to a third current speed of the motor in
motion.
5. The method of claim 1, further comprising the step of applying a
third phase-reversed voltage to the voltage input terminal of the
motor in motion if the motor is still in motion after the step of
electrically shorting the voltage input terminal, wherein the third
phase-reversed voltage corresponds to a third current speed of the
motor in motion.
6. A control system for a washing machine, the system comprising: a
motor rotating at least one of a washing tub and an agitator
provided in the washing machine in a wash cycle; a motor brake unit
initially applying a first phase-reversed voltage to a voltage
input terminal of the motor when an interruption command for
braking the motor in motion is generated during the wash cycle, the
first phase-reversed voltage corresponding a first current speed of
the motor in motion, and a controller measuring a second current
speed of the motor and generating a control signal if a second
phase-reversed voltage is higher than or equal to a critical
voltage level, the second phase-reversed voltage corresponding to
the second current speed of the motor, wherein the motor brake unit
electrically shorts the voltage input terminal of the motor upon
receiving the control signal from the controller.
7. The control system of claim 6, further comprising: a power
supply generating an AC power voltage; and a transformer converting
the AC power voltage into a DC power voltage and supplying the
converted DC voltage to the motor brake unit in order to drive the
motor.
8. The control system of claim 6, wherein the interruption command
is generated when a user cuts off a power supply to the washing
machine, manually touches a key control panel, or opens a door of
the washing machine during the wash cycle.
9. The control system of claim 6, wherein the critical voltage
level is predetermined such that the motor generates a brake noise
if the second phase-reversed voltage is higher than or equal to the
critical voltage level and is applied to the voltage input terminal
of the motor.
10. The control system of claim 6, wherein the motor brake unit
further applies a third phase-reversed voltage to the voltage input
terminal of the motor if the second current speed is lower than the
critical voltage value, the third phase-reversed voltage
corresponding to a third current speed of the motor in motion.
11. A method of controlling a motor-driven washing machine having a
load controller, the method comprising the steps of: initiating a
wash cycle by operating a plurality of load units including a motor
according to a wash option selected by a user; transmitting a brake
control signal to the load controller if an opening of a washer
door provided in the washing machine is detected, the load
controller executing a load-brake algorithm to brake operations of
the plurality of load units in response to the brake control
signal; determining whether the load-brake algorithm is properly
executed by the load controller by communicating with the load
controller; and transmitting control signals directly to the
plurality of the load units so as to brake the operations of the
plurality of the load units if the load-brake algorithm is properly
executed by the load controller.
12. The method of claim 11, wherein the plurality of load units
comprises at least one of a motor rotating a washing tub or an
agitator provided in the washing machine, a water supply unit
supplying water to the tub, and a drain unit draining water from
the tub.
13. The method of claim 11, wherein the step of determining
includes the steps of: receiving operation information of the
plurality of load units from the load controller; and analyzing the
received operation information of the plurality of the load units
in order to determine whether the load-brake algorithm is properly
executed by the load controller.
14. The method of claim 13, wherein the operation information
includes speed information of the motor.
15. The method of claim 13, wherein the operation information of
the plurality of load units is received from the load controller
through a serial data communication line connected to the load
controller.
16. A control system for a washing machine, the system comprising:
a door sensor detecting an opening of a washer door provided in the
washing machine; a load controller coupled to the door sensor for
executing a load-brake algorithm to brake operations of a plurality
of load units of the washing machine when the opening of the washer
door is detected by the door sensor; a main controller transmitting
control signals directly to the plurality of load units so as to
brake the operations of the plurality of load units if the
load-brake algorithm is not properly executed by the load
controller.
17. The controller system of claim 16, further comprising a display
unit displaying an error message indicating that the execution of
the load-brake algorithm by the load controller has failed.
18. The control system of claim 16, wherein the plurality of load
units comprises at least one of a motor rotating a washing tub or
an agitator provided in the washing machine, a water supply unit
supplying water to the tub, and a drain unit draining water from
the tub.
19. The control system of claim 16, wherein the main controller
receives operation information of the plurality of load units from
the load controller and analyzes the received information in order
to determine whether the load-brake algorithm is properly executed
by the load controller.
20. The control system of claim 19, wherein the main controller
receives the operation information of the plurality of load units
through a serial data communication line connected between the load
controller and the main controller.
21. A method of controlling a motor-driven washing machine, the
method comprising the steps of: initiating a wash cycle by
operating a motor provided in the washing machine according to a
washing option selected by a user; generating a motor-brake signal
to brake the operation of the motor when a motor-interruption
command is generated and measuring a brake period which represents
a total length of time it takes to completely stop the operation of
the motor; determining malfunction of the motor based on whether
the measured brake period exceeds a predetermined period of time;
and displaying a warming message on a display unit, the message
indicating the determined malfunction of the motor.
22. The method of claim 21, wherein the determining step comprises
the steps of: storing the measured brake period in a memory if the
measured brake period exceeds the predetermined period of time;
determining whether a total number of brake periods stored in the
memory until the present time is greater than a threshold frequency
value; determining the malfunction of the motor if the total number
of the stored brake periods is greater than the threshold frequency
value.
23. The method of claim 21, wherein the motor-interruption command
is generated when the user manually touches a key control panel or
opens a washer door of the washing machine during the wash
cycle.
24. The method of claim 21, further comprising the step of
continuing the wash cycle according to the washing option selected
by the user if the measured brake period is less than the
predetermined period of time.
25. The method of claim 21, wherein the initiating step includes
the step of rotating the motor so as to rotate a washing tub or an
agitator provided in the washing machine according to the washing
option selected by the user.
26. A control system for a washing machine, the control system
comprising: a motor rotating a washing tub or an agitator provided
in the washing machine according to a washing option selected by a
user; a microprocessor operatively coupled to the motor for braking
operation of the motor when a motor-interruption command is
generated and measuring a brake period which represents a total
length of time it takes to completely stop the operation of the
motor, the microprocessor determining malfunction of the motor
based on whether the measured brake period exceeds a predetermined
period of time; and a display unit displaying a warning message
indicating the determined malfunction of the motor upon receiving a
control signal from the microprocessor.
27. The control system of claim 26, further comprising a memory
storing the measured brake period if the measured brake period
exceeds the predetermined period of time.
28. The control system of claim 27, wherein the microprocessor
determines the malfunction of the motor if a total number of brake
periods that are stored in the memory until the present time is
greater than a threshold frequency value.
29. The control system of claim 27, wherein the memory is an EEPROM
and the display unit is an LCD.
30. The control system of claim 26, further comprising a timer that
measures the total length of time it takes to completely stop the
operation of the motor.
31. A method of controlling a motor-driven washing machine, the
method comprising the steps of: increasing a speed of a motor from
zero to a first predetermined speed W.sub.1 to initiate a spin
cycle, during which the motor rotates a washing tub containing a
load of clothes to be dehydrated; reducing the motor speed from WV
to a second predetermined speed W.sub.2 and measuring a
deceleration period that it takes to reduce the motor speed from
W.sub.1 to W.sub.2; increasing the motor speed from W.sub.2 to a
third predetermined speed W.sub.3; braking the motor according to a
slow brake logic if a first interruption of the motor is ordered
during the step of increasing the motor speed from W.sub.2 to
W.sub.3; increasing the motor speed from W.sub.3 to a fourth
predetermined speed W.sub.4; and selecting one of plurality of
rapid-brake logics on the basis of the measured deceleration period
and braking the motor according to the selected rapid-brake logic
if a second interruption of the motor is ordered during the step of
increasing the motor speed from W.sub.3 to W.sub.4.
32. The method of claim 31, wherein the step of reducing the motor
speed from W.sub.1 to W.sub.2 is achieved by cutting off a power
supply to the motor in motion.
33. The method of claim 31, further comprising the steps of:
maintaining the motor speed of W.sub.4 for a predetermined spin
period; and braking the motor according to the selected rapid-brake
logic if a third interruption of the motor is ordered during the
step of maintaining the motor speed of W.sub.4.
34. The method of claim 31, further comprising the steps of:
reducing the motor speed from W.sub.4 to zero to terminate the spin
cycle; and braking the motor in motion according to the selected
rapid-brake logic if a third interruption of the motor is ordered
during the step of reducing the motor speed from W.sub.4 to zero
and if the motor speed is greater than W.sub.3.
35. The method of claim 34, further comprising the step of braking
the motor according to the slow brake logic if the third
interruption of the motor is ordered during the step of reducing
the motor speed from W.sub.4 to zero and if the motor speed is less
than or equal to W.sub.3.
36. The method of claim 34, wherein the step of reducing the motor
speed from W.sub.4 to zero is achieved by cutting off a power
supply to the motor in motion.
37. The method of claim 31, further comprising the step of braking
the motor according to the slow brake logic if a third interruption
of the motor is ordered during the step of increasing the motor
speed from zero to W.sub.1.
38. The method of claim 31, further comprising the step of braking
the motor according to the slow brake logic if a third interruption
of the motor is ordered during the step of reducing the motor speed
from W.sub.1 to W.sub.2.
39. The method of claim 31, wherein the first interruption of the
motor is ordered when a user inputs a motor-interrupting command by
turning the power of the washing machine, opening of a washer door,
or manually touching a key control panel during the step of
increasing the motor speed from W.sub.2 to W.sub.3.
40. The method of claim 31, wherein the second interruption of the
motor is ordered when a user inputs a motor-interrupting command by
turning the power of the washing machine, opening of a washer door,
or manually touching a key control panel during the step of
increasing the motor speed from W.sub.3 to W.sub.4.
41. A method of controlling a motor-driven washing machine, the
method comprising the steps of: applying a phase-reversed voltage
to a voltage terminal of a motor in motion to brake the motor when
a motor-interruption command is generated during a wash or spin
cycle, the motor generating a reverse voltage and a reverse current
when being braked; initially reducing the reverse voltage generated
by the motor by allowing the reverse current to flow through a
braking resistor connected to the motor if the reverse voltage is
higher than a predetermined voltage level; determining malfunction
of the braking resistor on the basis of an actual current-flow
period of the braking resistor; and electrically shorting the
voltage terminal of the motor for a predetermined period of time if
the malfunction of the braking resistor is determined.
42. The method of claim 41, the step of determining malfunction
comprises: determining the malfunction of the braking resistor if
the actual current-flow period of the braking resistor is less than
a normal current-flow period; and determining the malfunction of
the braking resistor if the actual current-flow period of the
braking resistor is greater than the normal current-flow
period.
43. The method of claim 42, wherein the normal current-flow period
is predetermined to represent a length of time that it takes to
flow the reverse current through the braking resistor that operates
in a normal condition.
44. The method of claim 41, further comprising the step of further
reducing the initially reduced reverse voltage by further allowing
the reverse current to flow through the braking resistor if the
malfunction of the motor is not deter-mined.
45. The method of claim 41, further comprising the step of
repeating the step of applying the phase-reversed voltage if the
reverse voltage is less than or equal to the predetermined voltage
level.
46. A control system for a washing machine, the control system
comprising: a motor rotating a washing tub or an agitator provided
in the washing machine in a wash or spin cycle; a motor driving
unit applying a phase-reversed voltage to a voltage terminal of the
motor in motion if a motor-interruption command is generated, the
motor generating a reverse voltage and a reverse current when the
phase-reversed voltage is applied; a braking resistor connected to
the motor; and a microprocessor initially reducing the reverse
voltage generated by the motor by allowing the reverse current to
flow through the braking resistor if the reverse voltage is higher
than a predetermined voltage level, the microprocessor electrically
shorting the voltage terminal of the motor for a predetermined
period of time if it determines malfunction of the braking resistor
on the basis of an actual current-flow period of the braking
resistor.
47. The control system of claim 46, wherein the microprocessor
determines the malfunction of the braking resistor if the actual
current-flow period is not equal to a normal current-flow
period.
48. The control system of claim 47, wherein the normal current-flow
period is predetermined to represent a length of time it takes to
flow the reverse current through the braking resistor that operates
in a normal condition.
49. The control system of claim 46, wherein the microprocessor
further reduces the initially reduced reverse voltage by further
allowing the reverse current to flow through the braking resistor
if the actual current-flow period is equal to a normal current-flow
period.
50. The control system of claim 46, wherein the microprocessor
generates a control signal to the motor driving unit to further
apply the phase-reversed voltage to voltage terminal of the motor
if the reverse voltage is less than or equal to the predetermined
voltage level.
51. A method of controlling a motor-driven washing machine, the
method comprising the steps of: (a) determining whether a current
DC voltage of a driving unit driving a motor is less than or equal
to a predetermined voltage level for each predetermined period; (b)
measuring a current leading phase angle of the current DC voltage
if the current voltage is less than or equal to the predetermined
voltage level; and (c) decreasing the current leading phase angle
of the current DC voltage by a first predetermined level if the
measured leading phase angle is greater than zero.
52. The method of claim 51, further comprising the steps of: (d)
measuring a current pulse width modulation (PWM) duty if the
measured leading phase angle is equal to zero; and (e) decreasing
the current PWM duty by a second predetermined level if the
measured PWM duty if greater than zero.
53. The method of claim 52, wherein the first predetermined level
is equal to the second predetermined level.
54. The method of claim 52, further comprising the steps of: (f)
determining whether the motor is stopped; and (g) repeating steps
(a) to (e) if it is determined in step (f) that the motor is not
stopped.
55. The method of claim 51, further comprising the steps of: (f)
determining whether the motor is stopped; and (g) repeating steps
(a) to (c) if it is determined in step (f) that the motor is not
stopped.
56. A control system for a motor-driven washing machine, the
control system comprising: an electrical motor; a driving unit that
applies an input voltage to the motor to drive the motor; a
voltmeter that measures a reverse voltage generated by the motor
for each predetermined period; and a microprocessor reducing a
speed of the motor if the measured reverse voltage is less than or
equal to a predetermined voltage level.
57. The control system of claim 56, further comprising a timer that
determines whether the each predetermined period has elapsed.
58. The control system of claim 56, wherein the microprocessor is
configured to measure a current leading phase angle if the measured
reverse voltage is less than or equal to the predetermined voltage
level, and to decrease the current leading phase angel by a first
predetermined level if the measured leading phase angel is greater
than zero.
59. The control system of claim 58, wherein the microprocessor is
further configured to measure a current pulse width modulation
(PWM) duty if the measured leading phase angel is equal to zero,
and to decrease the current PWM duty by a second predetermined
level if the measured PWM duty is greater than zero.
60. The control system of claim 59, wherein the first predetermined
level is equal to the second predetermined level.
61. A method of controlling a motor-driven washing machine, the
method comprising the steps of: determining whether a command for a
spin cycle is received from a user; and locking a washer door on
the basis of whether a speed of a motor reaches a first
predetermined speed if the spin cycle command is received, the
motor rotating a washing tub containing a load of clothes to be
dehydrated.
62. The method of claim 61, wherein the step of locking the washer
door comprises: increasing the motor speed from zero to the first
predetermined speed to initiate the spin cycle; and generating a
control signal to a door locking unit if the motor speed is equal
to the first predetermined speed, the door locking unit locking the
washer door upon receiving the control signal.
63. The method of claim 62, further comprising the steps of:
further increasing the motor speed from the first predetermined
speed to a second predetermined speed; maintaining the motor speed
of the second predetermined speed for a predetermined period for
the spin cycle; and braking the motor in motion if the
predetermined period is elapsed.
64. The method of claim 62, wherein the first predetermined speed
is 700 RPM and the second predetermined speed is 1000 RPM.
65. The method of claim 61, wherein the command for the spin cycle
is received from the user through a key input unit of the washing
machine.
66. A control system for a washing machine, the control system
comprising: a washing tub containing a load of clothes to be
dehydrated; an electrical motor rotating the washing tub if a
command for a spin cycle is received from a user; and a
microprocessor locking a washer door on the basis of whether a
speed of the motor reaches a first predetermined speed.
67. The control system of claim 66, wherein the microprocessor
initially increases the motor speed from zero to the first
predetermined speed, the microprocessor further generating a
control signal to lock the washer door if the motor speed is equal
to the first predetermined speed.
68. The control system of claim 67, further comprising a door
locking unit that locks the washer door upon receiving the control
signal from the microprocessor.
69. The control system of claim 66, further comprising a key input
unit, through which the user inputs the command for the spin
cycle.
70. The control system of claim 66, wherein the first predetermined
speed is 700 RPM.
71. A method of controlling a motor-driven washing machine, the
method comprising the steps of: determining whether a first current
speed of a motor is less than a first predetermined speed if a
motor-interruption of the motor is generated during a spin cycle,
the motor rotating a washing tub containing a load of clothes to be
dehydrated during the spin cycle; and braking the motor in motion
by shorting power terminals of the motor for a first predetermined
period if the first current speed is less than the first
predetermined speed.
72. The method of claim 71, further comprising the step of applying
phase-reversed voltages to the power terminals for a second
predetermined period if a second current speed of the motor is less
than the first predetermined speed and greater than a second
predetermined speed.
73. The method of claim 72, further comprising the step of allowing
a braking resistor connected to the motor to flow reverse currents
generated by the motor so as to dissipate electrical power into
heat if the second current speed of the motor is less than the
first predetermined speed and greater than the second predetermined
speed.
74. The method of claim 72, further comprising the step of braking
the motor by shorting the power terminals of the motor if a third
current speed of the motor is less than the second predetermined
speed.
75. The method of claim 71, wherein the motor-interruption of the
motor is generated when a user directly inputs a command for
braking the motor or opens a washer door.
76. A control system for a washing machine, the control system
comprising: a washing tub containing a load of clothes to be
dehydrated; a motor rotating to the washing tub during a spin
cycle; and a microprocessor braking the motor shorting power
terminals of the motor if a motor-interruption is generated during
the spin cycle and if a first current speed of the motor is less
than a first predetermined speed.
77. The control system of claim 76, wherein the microprocessor
further brakes the motor by applying phase-reversed voltage to the
power terminals for a second predetermined period if a second
current speed of the motor is less than the first predetermined
speed and greater than a second predetermined speed.
78. The control system of claim 77, wherein the microprocessor
allows a braking resistor connected to the motor to flow reverse
currents generated by the motor if the second current speed of the
motor is less than the first predetermined speed and greater than
the second predetermined speed.
79. The control system of claim 77, wherein the microprocessor
further brakes the motor by shorting the power terminals of the
motor if a third current speed of the motor is less than the second
predetermined speed.
80. The control system of claim 76, wherein the motor-interruption
of the motor is generated when a user directly inputs a command for
braking the motor or opens a washer door.
81. A circuit for limiting a motor current in an electrical
appliance, the circuit comprising: a first resistor and a dip
switch connected between a power source and a ground in series, the
dip switch comprising a plurality of resistors having different
resistances; a capacitor connected to the dip switch in parallel;
an op amplifier having an inverting input connected to a node
between the first resistor and the dip switch; and a third resistor
connected between an noninverting input of the op amplifier and a
ground, wherein any one of the plurality of resistors of the dip
switch can be conveniently selected for limiting a current that
flows through the third resistor.
82. A method of controlling a motor-driven washing machine having a
motor and a pair of a transistor and a braking resistor connected
to the motor in parallel for limiting the reverse voltages
generated by the motor during a motor brake, the resistor being
connected to the transistor in series, the method comprising the
steps of: measuring a voltage of a node between the transistor and
the braking resistor; displaying a warning message indicating that
the brake resistor is in an inoperative condition if the measured
voltage is equal to zero; repeating the step of determining if a
command for a wash cycle is received; and initiating the wash cycle
if the measured voltage of the node is not equal to zero.
83. The method of claim 82, further comprising the step of
generating a warning sound if the measured voltage is equal to
zero.
84. A control system for a washing machine, the control system
comprising: a motor rotating a wash tub or an agitator of the
washing machine; a driving unit that drives the motor by applying
input voltages to the motor; a pair of a braking resistor and a
transistor connected to the driving unit in parallel, the
transistor being connected to the braking resistor in series; a
voltmeter measuring a voltage of a node between the transistor and
the braking resistor; and a microprocessor generating a warning
signal if the measured voltage of the node is not equal to
zero.
85. The control system of claim 84, further comprising a display
unit displaying a warning message upon receiving the warning
signal, the warning message indicating that the brake resistor is
in an inoperative condition.
86. The control system of claim 84, further comprising a sound
generating unit generating a warning sound upon receiving the
warning signal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Application
No. P2002-26886 filed on May 15, 2002, Korean Application No.
P2002-27127 filed on May 16, 2002, Korean Application No.
P2002-27132 filed on May 16, 2002, Korean Application No.
P2002-40211 filed on Jul. 11, 2002, Korean Application No.
P2002-40292 filed on Jul. 11, 2002, Korean Application No.
P2002-44687 filed on Jul. 29, 2002, Korean Application No.
P2002-73580 filed on Nov. 25, 2002, Korean Application No.
P2002-73898 filed on Nov. 26, 2002, Korean Application No.
P2002-74052 filed on Nov. 26, 2002, and Korean Application No.
P2002-74054 filed on Nov. 26, 2002, all of which are hereby
incorporated by reference as if fully set forth herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a washing machine, and more
particularly, to a method of controlling a motor-driven washing
machine and a control system for the same.
[0004] 2. Discussion of the Related Art
[0005] Motor-driven automatic washing machines are common these
days. A typical washing machine may include a motor for driving an
agitator and a rotatable tub severing both as a wash tub and a
dehydration tub and the motor is coupled to a drive shaft. During a
typical wash or rinse cycle, the motor is caused to rotate back and
forth to agitate the clothes and water in the wash tub for cleaning
or rinsing of the clothes.
[0006] In addition, during a spine cycle, the motor spins the wash
tub containing a load of wet clothes to be dehydrated to remove
water from the wet clothes by centrifugal force. Because the wash
tub rotates at a very high speed, many problems can occur. For
example, if the operation of the motor is not stopped properly when
a user mistakenly opens a washer door and sticks a hand into inside
of the tub, the user may be seriously harmed. The user should be
advised of such error promptly so that the error of the motor or
any other components that associates with the motor can be quickly
fixed.
[0007] In another example, when a control for braking a motor in
motion during a spin cycle is not properly done, the motor-clutch
mechanism may generates a noise and the mechanism can be damaged
due to the motion of the heavy wash tub at a high speed.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention is directed to a method
of controlling a motor-driven washing machine and a control system
for the same that substantially obviate one or more problems due to
limitations and disadvantages of the related art.
[0009] An object of the present invention is to provide a method of
controlling a motor-driven washing machine and a control system for
the same that prevent a motor-clutch mechanism from generating a
noise and being damaged.
[0010] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same, in which a proper control can be achieved even
if an initial algorithm for braking a motor is not executed
properly.)
[0011] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same in which, malfunction of a motor during a motor
interruption is determined and a corresponding error message is
displayed for warning a user of the malfunction.
[0012] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine that performs
a motor interruption based on the weight of a load of clothes to be
washed or dehydrated.
[0013] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same that prevent a motor from being damaged due to
reverse voltages generated by the motor during motor-brake
operation.
[0014] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same, in which malfunction of a braking resistor is
detected and motor operation is stopped for avoiding any motor
damage.
[0015] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same that minimize the time it takes to reduce the
motor speed.
[0016] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same, in which a washer door is locked only when the
speed of a motor reaches a predetermined speed.
[0017] Another object of the present invention is to provide a
method of controlling a motor-driven washing machine and a control
system for the same that prevent the motor from being damaged
during a spin cycle.
[0018] A further object of the present invention is to provide a
circuit for limiting a motor current in an electrical appliance
that the value of the limiting current can be varied.
[0019] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0020] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a method of controlling a motor-driven
washing machine includes the steps of generating an interruption
command for braking a motor in motion during a wash cycle; applying
a first phase-reversed voltage to a voltage input terminal of the
motor in motion, the first phase-reversed voltage corresponding to
a first current speed of the motor; and electrically shorting the
voltage input terminal of the motor for a predetermined period of
time if a second phase-reversed voltage is higher than or equal to
a critical voltage level, the second phase-reversed voltage
corresponding to a second current speed of the motor.
[0021] In another aspect of the present invention, a control system
for a washing machine includes a motor rotating at least one of a
washing tub and an agitator provided in the washing machine in a
wash cycle; a motor brake unit initially applying a first
phase-reversed voltage to a voltage input terminal of the motor
when an interruption command for braking the motor in motion is
generated during the wash cycle, the first phase-reversed voltage
corresponding a first current speed of the motor in motion, and a
controller measuring a second current speed of the motor and
generating a control signal if a second phase-reversed voltage is
higher than or equal to a critical voltage level, the second
phase-reversed voltage corresponding to the second current speed of
the motor, wherein the motor brake unit electrically shorts the
voltage input terminal of the motor upon receiving the control
signal from the controller.
[0022] In another aspect of the present invention, a method of
controlling a motor-driven washing machine having a load controller
includes the steps of initiating a wash cycle by operating a
plurality of load units including a motor according to a wash
option selected by a user; transmitting a brake control signal to
the load controller if an opening of a washer door provided in the
washing machine is detected, the load controller executing a
load-brake algorithm to brake operations of the plurality of load
units in response to the brake control signal; determining whether
the load-brake algorithm is properly executed by the load
controller by communicating with the load controller; and
transmitting control signals directly to the plurality of the load
units so as to brake the operations of the plurality of the load
units if the load-brake algorithm is properly executed by the load
controller.
[0023] In another aspect of the present invention, a control system
for a washing machine includes a door sensor detecting an opening
of a washer door provided in the washing machine; a load controller
coupled to the door sensor for executing a load-brake algorithm to
brake operations of a plurality of load units of the washing
machine when the opening of the washer door is detected by the door
sensor; a main controller transmitting control signals directly to
the plurality of load units so as to brake the operations of the
plurality of load units if the load-brake algorithm is not properly
executed by the load controller.
[0024] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
initiating a wash cycle by operating a motor provided in the
washing machine according to a washing option selected by a user;
generating a motor-brake signal to brake the operation of the motor
when a motor-interruption command is generated and measuring a
brake period which represents a total length of time it takes to
completely stop the operation of the motor; determining malfunction
of the motor based on whether the measured brake period exceeds a
predetermined period of time; and displaying a warning message on a
display unit, the message indicating the determined malfunction of
the motor.
[0025] In another aspect of the present invention, a control system
for a washing machine includes a motor rotating a washing tub or an
agitator provided in the washing machine according to a washing
option selected by a user; a microprocessor operatively coupled to
the motor for braking operation of the motor when a
motor-interruption command is generated and measuring a brake
period which represents a total length of time it takes to
completely stop the operation of the motor, the microprocessor
determining malfunction of the motor based on whether the measured
brake period exceeds a predetermined period of time; and a display
unit displaying a warning message indicating the determined
malfunction of the motor upon receiving a control signal from the
microprocessor.
[0026] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
increasing a speed of a motor from zero to a first predetermined
speed W to initiate a spin cycle, during which the motor rotates a
washing tub containing a load of clothes to be dehydrated; reducing
the motor speed from W.sub.1 to a second predetermined speed
W.sub.2 and measuring a deceleration period that it takes to reduce
the motor speed from W.sub.1 to W.sub.2; increasing the motor speed
from W.sub.2 to a third predetermined speed W.sub.3; braking the
motor according to a slow brake logic if a first interruption of
the motor is ordered during the step of increasing the motor speed
from W.sub.2 to W.sub.3; increasing the motor speed from W.sub.3 to
a fourth predetermined speed W.sub.4; and selecting one of
plurality of rapid-brake logics on the basis of the measured
deceleration period and braking the motor according to the selected
rapid-brake logic if a second interruption of the motor is ordered
during the step of increasing the motor speed from W.sub.3 to
W.sub.4.
[0027] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
applying a phase-reversed voltage to a voltage terminal of a motor
in motion to brake the motor when a motor-interruption command is
generated during a wash or spin cycle, the motor generating a
reverse voltage and a reverse current when being braked; initially
reducing the reverse voltage generated by the motor by allowing the
reverse current to flow through a braking resistor connected to the
motor if the reverse voltage is higher than a predetermined voltage
level; determining malfunction of the braking resistor on the basis
of an actual current-flow period of the braking resistor; and
electrically shorting the voltage terminal of the motor for a
predetermined period of time if the malfunction of the braking
resistor is determined.
[0028] In another aspect of the present invention, a control system
for a washing machine includes a motor rotating a washing tub or an
agitator provided in the washing machine in a wash or spin cycle; a
motor driving unit applying a phase-reversed voltage to a voltage
terminal of the motor in motion if a motor-interruption command is
generated, the motor generating a reverse voltage and a reverse
current when the phase-reversed voltage is applied; a braking
resistor connected to the motor; and a microprocessor initially
reducing the reverse voltage generated by the motor by allowing the
reverse current to flow through the braking resistor if the reverse
voltage is higher than a predetermined voltage level, the
microprocessor electrically shorting the voltage terminal of the
motor for a predetermined period of time if it determines
malfunction of the braking resistor on the basis of an actual
current-flow period of the braking resistor.
[0029] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
determining whether a current DC voltage of a driving unit driving
a motor is less than or equal to a predetermined voltage level for
each predetermined period; measuring a current leading phase angle
of the current DC voltage if the current voltage is less than or
equal to the predetermined voltage level; and decreasing the
current leading phase angle of the current DC voltage by a first
predetermined level if the measured leading phase angle is greater
than zero.
[0030] In another aspect of the present invention, a control system
for a motor-driven washing machine includes an electrical motor; a
driving unit that applies an input voltage to the motor to drive
the motor; a voltmeter that measures a reverse voltage generated by
the motor for each predetermined period; and a microprocessor
reducing a speed of the motor if the measured reverse voltage is
less than or equal to a predetermined voltage level.
[0031] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
determining whether a command for a spin cycle is received from a
user; and locking a washer door on the basis of whether a speed of
a motor reaches a first predetermined speed if the spin cycle
command is received, the motor rotating a washing tub containing a
load of clothes to be dehydrated. The step of locking the washer
door includes increasing the motor speed from zero to the first
predetermined speed to initiate the spin cycle; and generating a
control signal to a door locking unit if the motor speed is equal
to the first predetermined speed, the door locking unit locking the
washer door upon receiving the control signal.
[0032] In another aspect of the present invention, a control system
for a washing machine includes a washing tub containing a load of
clothes to be dehydrated; an electrical motor rotating the washing
tub if a command for a spin cycle is received from a user; and a
microprocessor locking a washer door on the basis of whether a
speed of the motor reaches a first predetermined speed.
[0033] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
determining whether a first current speed of a motor is less than a
first predetermined speed if a motor-interruption of the motor is
generated during a spin cycle, the motor rotating a washing tub
containing a load of clothes to be dehydrated during the spin
cycle; and braking the motor in motion by shorting power terminals
of the motor for a first predetermined period if the first current
speed is less than the first predetermined speed. The method
further includes the steps of applying phase-reversed voltages to
the power terminals for a second predetermined period if a second
current speed of the motor is less than the first predetermined
speed and greater than a second predetermined speed; and allowing a
braking resistor connected to the motor to flow reverse currents
generated by the motor so as to dissipate electrical power into
heat if the second current speed of the motor is less than the
first predetermined speed and greater than the second predetermined
speed.
[0034] In another aspect of the present invention, a control system
for a washing machine includes a washing tub containing a load of
clothes to be dehydrated; a motor rotating to the washing tub
during a spin cycle; and a microprocessor braking the motor
shorting power terminals of the motor if a motor-interruption is
generated during the spin cycle and if a first current speed of the
motor is less than a first predetermined speed.
[0035] In another aspect of the present invention, a circuit for
limiting a motor current in an electrical appliance includes a
first resistor and a dip switch connected between a power source
and a ground in series, the dip switch comprising a plurality of
resistors having different resistances; a capacitor connected to
the dip switch in parallel; an op amplifier having an inverting
input connected to a node between the first resistor and the dip
switch; and a third resistor connected between an noninverting
input of the op amplifier and a ground, wherein any one of the
plurality of resistors of the dip switch can be conveniently
selected for limiting a current that flows through the third
resistor.
[0036] In another aspect of the present invention, a method of
controlling a motor-driven washing machine includes the steps of
measuring a voltage of a node between the transistor and the
braking resistor; displaying a warning message indicating that the
brake resistor is in an inoperative condition if the measured
voltage is equal to zero; repeating the step of determining if a
command for a wash cycle is received; and initiating the wash cycle
if the measured voltage of the node is not equal to zero.
[0037] In another aspect of the present invention, a control system
for a washing machine includes a motor rotating a wash tub or an
agitator of the washing machine; a driving unit that drives the
motor by applying input voltages to the motor; a pair of a braking
resistor and a transistor connected to the driving unit in
parallel, the transistor being connected to the braking resistor in
series; a voltmeter measuring a voltage of a node between the
transistor and the braking resistor; and a microprocessor
generating a warning signal if the measured voltage of the node is
not equal to zero.
[0038] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings;
[0040] FIG. 1A illustrates a control system that drives a motor
provided in a washer according to a first embodiment of the present
invention;
[0041] FIG. 1B illustrates the detailed structures of the motor
brake unit 60, the transformer 50 and the motor 81 shown in FIG.
1A;
[0042] FIG. 1C illustrates a current flow (L1) of the motor brake
unit 60 when the phase-shifted voltage applied to the motor brake
unit 60 is less than V.sub.c;
[0043] FIG. 1D illustrates a method of controlling a motor provided
in a washer according to the first embodiment of the present
invention;
[0044] FIG. 2A illustrates an apparatus of controlling load units
(e.g., a motor) in a washer according to a second embodiment of the
present invention;
[0045] FIG. 2B illustrates a method of controlling load units in a
washer according to the second embodiment of the present
invention;
[0046] FIG. 3A illustrates an apparatus of detecting malfunction of
a motor in a washer according to a third embodiment of the present
invention;
[0047] FIG. 3B illustrates a method of detecting malfunction of a
motor in a washer according to the third embodiment of the present
invention;
[0048] FIG. 4A and FIG. 4B illustrate a method of interrupting
(braking) operation of a motor in a washer according to a fourth
embodiment of the present invention; FIG. 5A illustrates a control
system that drives a motor provided in a washer according to a
fifth embodiment of the present invention;
[0049] FIG. 5B illustrates a method of controlling a motor in a
washer according to the fifth embodiment of the present
invention;
[0050] FIG. 6A illustrates a control system that drives a motor
provided in a washer according to a sixth embodiment of the present
invention;
[0051] FIG. 6B illustrates a method of controlling a motor in a
washer according to the sixth embodiment of the present
invention;
[0052] FIG. 7A illustrates a control system controlling a motor in
a washer according to a seventh embodiment of the present
invention;
[0053] FIG. 7B illustrates a method of controlling a motor in a
washer according to the seventh embodiment of the present
invention;
[0054] FIG. 8A illustrates an apparatus of controlling operation of
a motor in a washer according to an eighth embodiment of the
present invention;
[0055] FIG. 8B illustrates a method of controlling operation of a
motor in a washer according to the eighth embodiment of the present
invention;
[0056] FIG. 9A illustrates a control system that drives a motor
provided in a washer according to a ninth embodiment of the present
invention;
[0057] FIG. 9B illustrates a method of controlling a motor in a
washer according to the ninth embodiment of the present invention;
and
[0058] FIG. 10 illustrates a circuitry for limiting a motor current
in an electrical appliance according to a tenth embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0059] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
Embodiment (1)
[0060] FIG. 1A illustrates a control system that drives a motor
provided in a washer according to a first embodiment of the present
invention. Referring to FIG. 1A, the control system includes a
power supply unit 40 rectifying and/or smoothing an AC power
voltage generated by a power source, a transformer 50 having a
converter (not illustrated) and for converting the rectified AC
voltage into a DC voltage and a capacitor (not illustrated) for
storing the converted DC voltage, a motor 81 rotating a tub and/or
an agitator provided in the washer, a motor brake unit 60 braking
the operation of the motor 81 by applying an input voltage to the
motor 81 upon receiving a brake control signal, and a controller 70
measuring the DC voltage stored by the transformer 50 and
generating the brake control signal to the motor brake unit 60.
[0061] The DC voltage stored in the capacitor of the transformer 50
is used for driving the motor 81, and the motor 81 transmits the
dynamic energy to a clutch (not illustrated) that engages with the
tub and/or agitator provided in the washer for washing a load of
clothes to be washed. When a user inputs a command for interrupting
(braking) the motor operation by turning the power of the washer
off, opening a washer door, or manually touching a key control
panel, the controller 70 generates a motor interruption signal to
the motor brake unit 60. In addition, the controller 70
continuously monitors the speed of the motor 81 and outputs the
motor speed information to the transformer 50, which then applies a
voltage corresponding to the motor speed to the motor brake unit
60.
[0062] The motor brake unit 60 shifts the phase of the voltage
outputted by the transformer 50 by 180 degrees and applies the
phase-shifted voltage (phase-reversed voltage) to the motor 81 so
as to brake the motor operation. However, when a phase-shifted
voltage corresponding to a speed value higher than a certain motor
speed is applied to the motor 81, a noise may be generated in the
motor-clutch mechanism and the mechanism may be damaged. This is
because the actual rotational displacement of the clutch is greater
than the rotational displacement of the motor 81 due to the
rotational speed difference between the motor 81 and the clutch.
For this reason, the controller 70 initially stores a critical
phase-shift voltage Vc that starts to generate the noise in the
motor-clutch mechanism and that may damage the mechanism, and it
performs a motor brake by shorting the power input terminals of the
motor 81 if the current phase-reversed voltage is greater than
V.sub.c.
[0063] FIG. 1B illustrates the detailed structures of the motor
brake unit 60, the transformer 50 and the motor 81 shown in FIG.
1A. As shown in FIG. 1B, the motor brake unit 60 comprises three
pairs of insulated gate bipolar transistors (hereinafter,
"transistor") connected in parallel, where each pair comprises two
transistors connected in series. A diode (D1 to D6) is connected to
each transistor, which can be shorted by the diode. Transistors T2,
T4 and T6, which are directly connected to three winded wires of
the motor 81, apply the voltage supplied by the transformer to the
winded wires of the motor 81, respectively, for operating or
braking the motor 81.
[0064] FIG. 1C illustrates a current flow (L1) of the motor brake
unit 60 when the phase-shifted voltage applied to the motor brake
unit 60 is less than V.sub.c. On the other hand, a current flow
(L2) of the motor brake unit 60 when the phase-shifted voltage is
greater than or equal to V.sub.c. In other words, if the controller
70 determines that the voltage being inputted to motor brake unit
60 is greater than or equal to V.sub.c, the motor brake unit 60
shorts the input terminals of the motor 81 as shown in FIG. 1B for
a predetermined period of time (e.g., 0.5 sec). As shown in FIG.
1B, the connections between the transformer 50 and the motor 81 are
shorted by activating T2, T4 and T6 and D2, D4 and D6 and by
deactivating T1, T3, and T5. Therefore, the voltage of the
transformer 50 is not applied, but instead, the voltage previously
applied to the winded wires 85 of the motor 81 are consumed for
braking the motor operation. After the input terminals of the motor
81 are shorted for 0.5 sec, the speed of the motor 81 is reduced
and the reduced motor speed is transmitted to the controller 70,
which then applies a voltage corresponding to the reduced motor
speed to the motor driving unit 60 so that the motor 81 can be
stopped without generating any noise in the motor-clutch
mechanism.
[0065] Reference will now be made in detail to a method of
controlling a motor provided in a washer according to the first
embodiment of the present invention, which is illustrated in FIG.
1D. Initially, a user inputs a command for interrupting (braking)
the motor operation by turning the power of the washer off, opening
a washer door, or manually touching a key input panel (SS1). Next,
the controller 70 controls the transformer 50 to apply a voltage
corresponding to the current motor speed to the motor brake unit
60, which then performs a motor brake by shifting the phase of the
voltage by 180 degrees and applying the phase-shifted voltage
(phase-reversed voltage) to the motor 81 (S2). Thereafter, the
controller 70 measures the current speed of the motor 81 again and
compares the voltage corresponding to the measured motor speed with
a critical phase-shift voltage Vc (S3), which is previously stored
by the controller and represents a value of the phase-shifted
voltage that causes the motor-cutch mechanism to generate a noise
if applied to the motor 81.
[0066] If the voltage corresponding to the current motor speed is
less than Vc, steps S2 and S3 are repeated again. On the other
hand, if the voltage is greater than or equal to Vc, the controller
70 performs a motor brake by shoring the power input terminals of
the motor 81 for a predetermined period of time T (e.g., 0.5 sec)
so that the voltage corresponding the current motor speed is not
applied to the motor 81. Next, if the controller 70 determines that
the operation of the motor 81 is stopped (S5), it terminates the
motor brake algorithm. Otherwise, steps S1 to S5 are repeated until
the motor operation is stopped.
Embodiment (2)
[0067] FIG. 2A illustrates an apparatus of controlling load units
(e.g., a motor) in a washer according to a second embodiment of the
present invention. Referring to FIG. 2A, the apparatus includes a
key input unit 210 receiving commands from a user for a wash cycle,
a door sensor 240 for sensing opening of a washer door of the
washer, and a load controller 230 that executes an interrupt
program or algorithm for interrupting operations of load units 260
upon receiving a signal indicating the opening of the washer door,
where the load units 260 include a motor rotating a tub and/or an
agitator provided in the washer, a water supply system supplying
water to the tub, and a drain system draining water from the tub.
The apparatus shown in FIG. 2A further includes a main controller
220 that generates control signals to initiate the wash cycle
according to the user's commands and controls the operations of the
load units based upon whether the interrupt program is properly
executed by the load controller 230. The apparatus further includes
a memory 250 (e.g., EEPROM) for storing a plurality of parameter
values that correspond to various washing options and a display
unit 270, such as an LCD display, that displays information
indicating the opening of the washer door upon receiving a control
signal from the main controller 220.
[0068] When a user inputs commands for a wash cycle through the key
input unit 210, the main controller 220 transmits the commands to
the load controller 230. Then the load controller 230 performs a
wash cycle by driving the load units 260 according to the received
commands. The load units 260 include a motor rotating a tub, and it
may further include a water supply supplying water to the tub and a
drain draining water from the tub.
[0069] When the door sensor 240 detects or senses opening of a
washer door, it sends a signal indicating the opening of the washer
door to the load controller 230 and the main controller 220.
Thereafter, the load controller 230 runs an interrupt program
(e.g., executing an interrupt algorithm) for interrupting or
suspending operations of the load units 260. The main controller
220 determines whether the load controller 230 has executed the
interrupt program properly. If the main controller 220 determines
that the load controller 230 has not executed the program properly,
it generates a direct control signal to the load units 260 for
properly interrupting or suspending the operations of the load
units 260. For example, the load controller 230 periodically
transmits speed (RPM) information of a motor which is operatively
coupled to the load controller 30 so that the main controller 220
can determine whether the load controller 230 has executed the
interrupt program properly by monitoring the speed information of
the motor.
[0070] Reference will now be made in detail to a method of
controlling load units in a washer according to the second
embodiment of the present invention, which is illustrated in FIG.
2B. Referring to FIG. 2B, the main controller 220 initially
generates control signals to initiate a wash cycle according to a
washing option selected by a user (S211). If the main controller
220 detects opening of a washer door during the wash cycle (S212),
it determines whether the load controller 230 has executed an
interruption program (e.g., an interrupt algorithm) properly by
receiving operation data of the load units 260 from the load
controller 230 via a data communication line, such as a serial
communication line, and by monitoring the received operation data
(S213). If it is determined in step S213 that an interruption
program is properly executed by the load controller 230, then the
main controller 220 allows the load controller to interrupt the
operations of the load units 260 (S214). On the other hand, if the
interrupt program is not properly executed, the main controller 220
sends direct control signals to the load units 260 for interrupting
the operations of the load units 260 (S215). One of the advantages
of controlling the load units of a washer according to the second
embodiment described above is that a reliable control for
interrupting operations of the load units is still achieved even
when any error occurs in interrupting the operations of the load
units by the load units.
Embodiment (3)
[0071] FIG. 3A illustrates an apparatus of detecting malfunction of
a motor in a washer according to a third embodiment of the present
invention. Referring to FIG. 3A, the apparatus includes a key input
unit 310 receiving commands from a user for a wash cycle, a motor
340 rotating a tub and/or an agitator in the washer, a speed
measuring unit 330 measuring the speed of the motor 340, and a
counter 320 that measures interruption periods of the motor 340. An
interruption period of the motor 340 represents a period of time
that it takes for the motor 340 to completely stop since an
interruption command is inputted by the user through the key input
unit 310 or opening of a washer door (not illustrated) of the
washer is detected. The apparatus shown in FIG. 3A further includes
a memory 370 (e.g., EEPROM) that stores the measured interruption
period of the motor 340 if the measured period is greater than a
predetermined length of time, a microprocessor 360 that determines
malfunction of the motor 340 based upon whether a total number of
the stored interruption periods, which are greater than the
predetermined length of time, is greater than a threshold
frequency, and a display unit 350 (e.g., an LCD) that indicates the
malfunction of the motor 340 upon receiving a control signal from
the microprocessor 360.
[0072] When the microprocessor 360 receives an interruption command
from the user through the key input unit 310 or detects opening of
a washer door of the washer, it generates an interruption signal to
the motor 340 to interrupt or stop operation of the motor 340.
Thereafter, the counter 320 measures an interruption period of the
motor 340, which represents a period of time it takes for the motor
340 to completely stop since the interruption signal is generated
by the microprocessor 360, and the microprocessor stores the
measured interruption period in the memory 370 if the measured
period is greater than a predetermined length of time. Next, the
microprocessor 360 determines whether a total number of the
interruption periods stored in the memory 370 is greater than a
threshold frequency. If the total number of periods is determined
to be the threshold frequency, the microprocessor 360 sends a
control signal to the display unit 350 to display a message
indicating malfunction of the motor 340 to the user.
[0073] Reference will now be made in detail to a method of
detecting malfunction of a motor in a washer according to the third
embodiment of the present invention, which is illustrated in FIG.
3B. Referring to FIG. 3B, when power is supplied to a washer (S31)
and the microprocessor 360 determines that a command for initiating
a wash cycle is received from the user through the key input unit
310 (S32), the microprocessor 360 initiates the wash cycle
according to a wash option selected by the user (S33). Thereafter,
when the microprocessor 360 determines that an interruption command
is received from the user through the key input unit 310 or opening
of a washer door of the washer is detected (S34), it generates an
interruption signal to interrupt or stop operation of the motor 340
and measures an interruption period of the motor 340 using the
counter 320 (S36). The interruption period of the motor 340
represents a period of time it takes to completely stop the
operation of the motor 360 since the interruption signal is
generated. On the other hand, if it is determined in step S34 that
no interruption command is received from the user and the opening
of the washer door is not detected, the microprocessor 360
continues the wash cycle (S35).
[0074] Referring back to FIG. 3B, after the interruption period of
the motor 340 is measured in step S36, the microprocessor 360
determines whether the measured interruption period is greater than
a predetermined length of time T.sub.predetermined (S37). If it is,
it stores the measured interruption period in the memory 370 (S38),
and otherwise, it finishes interrupting the operation of the motor
340 (S41). Next, the microprocessor 360 further determines whether
a total number of the interruption periods, which are stored in the
memory 370 up to the present time, is greater than a threshold
frequency value N.sub.predetermined (S39). If the total number of
periods is determined to be greater than the threshold frequency
value in step S39, the microprocessor 360 sends a display control
signal to the display unit 350 to display a message indicating
malfunction of the motor 340 to the user (S40). Using the apparatus
and method according to the third embodiment of the present
invention, a user can easily and conveniently be notified of
malfunction of the motor 340 when the operation of the motor is not
completely stopped within a predetermined length of time upon
receiving an interruption command from the microprocessor 360.
Therefore, the user can repair the motor in advance without
damaging the motor or any other component of the washer.
Embodiment (4)
[0075] FIG. 4 illustrates a method of interrupting (braking)
operation of a motor in a washer according to a fourth embodiment
of the present invention. The washer includes a motor rotating a
tub or an agitator, a microprocessor generating control signals to
control operation of the motor. Referring to FIG. 4, the
microprocessor of the washer initially increases the speed of the
motor W (S411). When W is determined to be greater or equal to a
first predetermined speed W.sub.1 (S412), the microprocessor turns
the motor power off (S413). On the other hand, if W is determined
to be less than W.sub.1 in step S412 and if interruption of the
motor operation is ordered (S414), the microprocessor interrupts
(brakes) the motor operation based on a slow-brake logic (S415).
The interruption of the motor operation gets ordered when a user
inputs a command for interrupting (braking) the motor operation by
turning the power of the washer off, opening a washer door, or
manually touching a key control panel.
[0076] After the motor power is turned off in step S413, power-free
rotation of the motor occurs and thereby W gradually decreases
(S416). If the microprocessor determines that the microprocessor
determines whether W is less than or equal to a second
predetermined speed W.sub.2 being less than W.sub.1 (S417), it
determines the weight of a load of clothes being contained in the
tub by measuring T that represents a length of time that it takes
for W to decrease from W.sub.1 to W.sub.2 (S418). On the other
hand, if W is determined to be still greater than W.sub.2 in step
S417 and if interruption of the motor operation is ordered (S419),
step S415 is repeated.
[0077] After the load weight is determined in step S418, the
microprocessor increases W (S420). If W is determined to be greater
than or equal to a third predetermined speed W.sub.3 which is
greater than W.sub.1 (S421), the microprocessor further increases W
(S423). On the other hand, if W is determined to be less than
W.sub.3 in step S421 and if interruption of the motor operation is
ordered (S422), step S415 is repeated. Referring back to step S423,
if W is determined to be greater than or equal to a fourth
predetermined speed W.sub.4 which is greater than W.sub.3 (S424),
the microprocessor maintains the motor speed to W.sub.4 and
performs a spin cycle (S425).
[0078] If W is determined to be less than W.sub.4 in step S424 and
if interruption of the motor operation is ordered (S426), the
microprocessor selects one of a plurality of rapid-brake logics on
the basis of T measured in step S418 and interrupts or brakes the
motor operation according to the selected rapid-brake logic
(S427-S432). For example, if T is determined to be less than or
equal to a first predetermined length of time T.sub.1 (S427), the
microprocessor brakes the motor operation based on a first
rapid-brake logic (S428). And if T is determined to be greater than
T.sub.1 but less than or equal to a second predetermined length of
time T.sub.2 (S429), the motor operation is interrupted based on a
second rapid-brake logic (S430). In other words, if T is determined
to be greater than an (n-1)th predetermined length of time
T.sub.n-1 but less than or equal to an nth predetermined length of
time T.sub.n where n=2, 3, 4, . . . N (S431), the microprocessor
brakes the motor operation based on an nth rapid-brake logic
(S432).
[0079] Referring back to step S425, if a spin period, during which
W.sub.4 is maintained, is determined to be greater than or equal to
a predetermined period of time E (S433), the microprocessor turns
off the motor power (S434). On the other hand, if the spin period
is determined to be less than E in step S433 and if interruption of
the motor operation is ordered (S435), the microprocessor selects
on of the plurality of rapid-brake logics on the basis of T
measured in step S428 and interrupts the motor operation according
to the selected rapid-brake logic (S427-S432). After the motor
power is turned off in step S434, if the microprocessor determines
in step S436 that W is less than or equal to W.sub.3 and if
interruption of the motor operation is ordered (S43.8), step 415 is
repeated. In addition, if W is determined to be greater than
W.sub.3 in step S436 and if interruption of the motor operation is
ordered (S437), steps S427 to S432 are repeated.
[0080] In the method of interrupting operation of the washer motor
shown in FIG. 4, an appropriate motor brake logic is selected based
on the weight of the load of clothes so that the optimal
interruption of the motor operation can be achieved while avoiding
any damage on the motor or any other components that associate with
the motor.
Embodiment (5)
[0081] FIG. 5A illustrates a control system that drives a motor
provided in a washer according to a fifth embodiment of the present
invention. Referring to FIG. 5A, the control system includes a
transformer 54 having a converter 54A and a first capacitor C.sub.1
for converting the AC power generated by the AC power source 52
into DC power, a switch 52A connecting or disconnecting the AC
power source 52 to the transformer 54, and a switching mode power
supply (SMPS) unit 56 transforming the DC voltage converted by the
transformer 54 into a voltage having a predetermined level.
[0082] The motor control system shown in FIG. 5A further includes a
relay unit 56A which is connected between the SMPS unit 56 and the
AC power source 52 and cuts off the AC power if its frequency is
higher than a predetermined frequency value, a first resistor
R.sub.1 connected to the relay unit 56A in parallel, a motor 51
rotating a tub or an agitator in the washer, a driving circuit 58
driving the motor 51 by supplying the voltage converted by the SMPA
unit 56 to the motor 51, a microprocessor 59 controlling operation
of the motor 51, an insulated gate bipolar transistor (IGBT) 57
performing pulse width modulation upon receiving a control signal
from the microprocessor 59, a voltage comparator 53 comparing the
reverse voltage generated by the motor 51 during a motor brake with
a predetermined voltage value, and a braking resistor 55
dissipating the reverse voltage generated by the motor 51 into heat
so as to prevent possible circuit damages due to the reverse
voltage.
[0083] Reference will now be made in detail to a method of
controlling a motor in a washer according to the fifth embodiment
of the present invention, which is illustrated in FIG. 5B.
Referring to FIG. 5B, when the microprocessor 59 determines that
any one of the conditions for braking operation of the motor 51 is
met, it sends interruption signals to the motor driving circuit 58,
which then applies phase-reversed input voltages to the motor 51
(S511). In step S511, the reverse voltages are then generated by
the motor 51 due to its rotation and they are applied to the
driving circuit 58. In a case where the motor 51 is driven by three
input voltages having three different phases, the reverse voltages
generated by the motor 51 during the motor brake also have three
phases. Therefore, the phases of the reverse voltages depend on the
phases of the input voltages that the driving circuit 58 applies to
the motor 51.
[0084] After the reverse voltages are generated by the motor 51 in
step S51, the microprocessor 59 measures the reverse voltages
generated in step S511 and determines whether the measured reverse
voltages are greater than a predetermined voltage value V.sub.1
(S512). If they are, the microprocessor 59 generates control
signals for a normal motor brake, in which the braking resistor 55
is allowed to dissipate energy due to the reverse voltages
generated by the motor 51 into heat (S513). Otherwise, steps S511
and S512 are repeated until the reverse voltages are determined to
be greater than V.sub.1.
[0085] Next, the microprocessor 59 measures a current-flow period
of the braking resistor 55 which represents a length of time that a
reverse current flows through the braking resistor 55 when the
reverse voltages are generated by the motor 51, and it further
determines whether the measured current-flow period is less than a
normal dissipate period T.sub.1 (S514). T.sub.1 represents a period
of time that it takes to dissipate all the reverse voltages by the
braking resistor 55 in a normal condition. If the measured
current-flow period is less than T.sub.1, the microprocessor 59
determines that the braking resistor 55 is opened.
[0086] If the measured current-flow period is determined to be not
less than the T.sub.1, the microprocessor 59 determines whether the
measured current-flow period is greater than T.sub.1 (S515). If the
measured current-flow period is greater than T.sub.1, it determines
that the braking resistor 55 is shorted. If it is determined that
the measured current-flow period is less than or greater than
T.sub.1 in step S514 or S515, the microprocessor 59 shorts a
corresponding node connected to the driving circuit 58 for a
predetermined period of time so as to reduce the reverse voltages
generated by the motor 51 (S516). When the node connected to the
driving circuit 58 is shorted, the reverse voltages of the motor 51
are reduced due to their phase differences. By doing so, any
circuit damage caused by high reverse voltages of the motor 51 can
be prevented during the motor brake.
[0087] After the reverse voltages are reduced in step S516 or the
measured current-flow period of the braking resistor 55 is
determined to be not greater than T.sub.1 in step S515, the
microprocessor 59 measures the reverse voltages of the motor 51
again and determines whether the measured reverse voltages are less
than the predetermined voltage value V.sub.1 (S517). If they are,
the microprocessor 59 terminates the operation of the motor 51
(S518).
Embodiment (6)
[0088] FIG. 6A illustrates a control system that drives a motor
provided in a washer according to a sixth embodiment of the present
invention. As shown in FIG. 6A, the system includes a rectifier 611
rectifying the AC power, a motor 612 rotating a tub or an agitator
of the washer, and a driving circuit 613 comprising a plurality of
insulating gate bipolar transistors (IGBT). The driving circuit 613
applies input voltages U, V, and W having three different phases,
respectively, to the motor 612 in a first operation mode and
applies phase-reversed voltages to the motor 612 in a second
operation mode so that the reverse voltages generated by the motor
612 due to its rotation are applied to the driving circuit 613.
[0089] The system shown in FIG. 6A further includes a switching
mode power supply (SMPS) unit 614 transforming the output of the
rectifier 611 into a voltage having a predetermined level (e.g.,
5V), a speedometer 615 measuring the rotational speed of the motor
612, a braking resistor R.sub.b dissipating the reverse voltages
generated by the motor 612 into heat so as to prevent possible
circuit damages, and a transistor T.sub.1 driving the braking
resistor R.sub.b. The system further includes a voltmeter 616 that
measures the output voltage of the rectifier 611 after the reverse
voltage of the motor 612 is dissipated in R.sub.b, a driver
microprocessor 617 controlling operations of the driving circuit
613 and the transistor T.sub.1 on the basis of the output voltage
measured by the voltmeter 616, a door opening sensor (not
illustrated) detecting opening of a washer door and sending a
corresponding signal to the drive microprocessor 617, a user
interface unit 618 having at least one a touch panel and a key
input unit for receiving operational commands from a user, a
display unit (e.g., LCD) 619 displaying a message indicating the
operation status of the washer, a sound generating unit 620, and a
main microprocessor 621 controlling the drive microprocessor 617 so
as to operate various components of the washer including the motor
612 according to the operational commands received by the user
interface unit 618.
[0090] The main microprocessor unit 621 detects an abnormal output
voltage of the rectifier 611 by communicating with the drive
microprocessor 617 and generates control signals to the display
unit 619 and the sound generating unit 620 so as to display a
warning message and a warning sound indicating the abnormal output
voltage of the rectifier 611. Because the brake resistor R.sub.b is
detachably provided in the control system as shown in FIG. 6A and
the voltmeter 616 measures the output voltage of the rectifier 611
using R.sub.b, the output voltage of the voltmeter 616 will be 0V
if R.sub.b is not provided at all or the connector 622 is
inoperatively provided.
[0091] Reference will now be made in detail to the operation of the
control system shown in FIG. 6A. When a user inputs commands for a
wash cycle through the user through interface unit 618, the main
microprocessor 621 transmits control signals to the drive
microprocessor 617 so as to drive various components of the washer
based on a plurality of operation parameters corresponding to a
wash option selected by the user. The drive microprocessor 617
initially rotates the motor 612 while monitoring the speed of the
motor 612 and performs the wash cycle by operating other components
such as a water supply system and a water drain system. On the
other hand, the main microprocessor 621 generates control signals
to the display unit 619 for displaying a current operation status
of the washer and to the sound generating unit 620 for generating a
warning sound if necessary.
[0092] During a wash cycle, the rotational direction of the motor
612 alternates between a clockwise direction and a
counter-clockwise direction. For example, in order to switch the
direction of the motor 612 which was initially rotating in a
clockwise direction in a first mode, the rotation of the motor 612
must be initially stopped. In addition, such brake or interruption
of the motor operation is often necessary when a washer door is
opened by a user during a spin (dehydration) cycle. Therefore, when
the drive microprocessor 617 determines that any one of the
conditions for braking the motor operation is met, it operates the
driving circuit 613 in a second operation mode, in which the
driving circuit 613 applies phase-reversed input voltages to the
motor 612 and the brake resistor R.sub.b operates to dissipates the
reverse voltage generated by the motor 611 so as to prevent any
circuit damages.
[0093] FIG. 6B is a flow chart illustrating a method of controlling
a motor in a washer according to the sixth embodiment of the
present invention. Initially, the drive microprocessor 617 measures
the output voltage of the rectifier 611 using the voltmeter 616
(S61). Next, if the drive microprocessor 617 determines that the
measured output voltage is 0V (S62), it transmits to the main
microprocessor 621 a warning signal indicating that the brake
resistor R.sub.b is not connected at all or is improperly
connected. Because the voltmeter 611 measures the output voltage of
the rectifier 611 passing through R.sub.b using a pair of resistors
R.sub.1 and R.sub.2 connected in series, the measured voltage of 0V
indicates that the power source voltage is being applied but
R.sub.b is improperly connected.
[0094] Upon receiving the warning signal from the drive
microprocessor 617, the main microprocessor 621 generate controls
signals to the display unit 619 and the sound generating unit 620
for displaying a warning message indicating R.sub.b is improperly
connected and for generating a warning sound (S63). If it is
determined in step S62 that the output voltage is not 0V, step S63
is skipped. Next, if the main microprocessor 621 determines that
operational commands for a wash cycle are inputted by a user
through the user interface unit 618 (S64), it further measures the
output voltage of the rectifier 611 using the voltmeter 616 and
determines whether the measured output voltage is ON (S65). If it
is, the main microprocessor does not initiate the wash cycle but
repeats step S65 after being in a standby mode for a predetermined
period of time. This step is essentially important for preventing
any chance of damaging the control system shown in FIG. 6A.
[0095] On the other hand, if it is determined in step S65 that the
measured output voltage is not 0V (meaning that R.sub.b is now
properly connected), the main microprocessor 621 initiates the wash
cycle by generating control signals to the drive microprocessor 617
so as to operate various components of the washer including the
motor 621 according to the operational commands received from the
user (S26).
Embodiment (7)
[0096] FIG. 7A illustrates a control system controlling a motor in
a washer according to a seventh embodiment of the present
invention. Referring to FIG. 7A, the control system includes a
motor 71 rotating a tub or an agitator of the washer, a transformer
72 generating a DC power voltage, and a motor driving unit 73
driving the motor 71 by applying the DC power voltage to the motor
71. The control system shown in FIG. 7A further includes a timer 74
counting a predetermined deceleration period, a voltmeter 75
measuring the reverse voltages generated due to reverse currents
generated by the motor 71 when interrupted, and a microprocessor 76
that generates a control signal to the driving unit 71 to decrease
the motor speed if the measured reverse voltages are less than a
predetermined voltage value.
[0097] The microprocessor 76 initially accelerates the motor speed
and controls the timer 74 to repeatedly count a predetermined
deceleration period so as to reduce the initially accelerated motor
speed for each deceleration period. In addition, the,
microprocessor 76 measures the DC input voltage of the motor
driving unit 71 for each deceleration period and maintains a
standby status to reduce the input voltage of the driving circuit
71 if the measured input voltage is higher than a predetermined
voltage level. The voltmeter 75 is connected to the DC link in
parallel and includes three resistors which are connected in
series. Therefore, the output of the voltmeter 75 is a voltage
subdivided by the resistors of the voltmeter 75.
[0098] On the other hand, if the measured DC voltage of the driving
unit 71 is less than the predetermined voltage level, the
microprocessor 76 measures the current leading phase angle .PHI.
and reduces the motor speed by reducing the leading phase angel by
a predetermined rate for each deceleration period. If the leading
phase angle d) becomes zero, the microprocessor 76 obtains the
current pulse width modulation (PWM) duty and reduces the motor
speed by reducing the PWM duty by a predetermined rate for each
deceleration period.
[0099] Reference will now be made in detail to a method of
controlling a motor in a washer according to the seventh embodiment
of the present invention, which is illustrated in FIG. 7B. When the
algorithm shown in FIG. 7B starts, the microprocessor 76 sends to a
control signal to the timer 74 to start measure a time T and
determines whether a predetermined deceleration period T.sub.c is
elapsed by checking whether T is greater than T.sub.c (S701). If
T.sub.c is elapsed, the microprocessor 76 initializes the timer 74
by setting T to zero (S702) and determines whether the current DC
voltage V of the driving unit 71 is less than or equal to a
predetermined voltage level V.sub.c (S703). If it is determined in
step S703 that V V.sub.c, then the microprocessor 76 measures the
current leading phase angle .PHI. of the DC voltage V of the
driving unit 71 (S704). If the measured leading phase angle .PHI.
is greater than zero (S705), the microprocessor 76 reduces the
leading phase angle .PHI. by a predetermined level .alpha. (S706).
Thereafter, if the microprocessor 76 determines that the motor 71
is not stopped (S711), step S701 and all the following steps are
repeated again as shown in FIG. 7B.
[0100] On the other hand, if it is determined in step S705 that the
measured leading phase angle .PHI. is not greater than zero, the
microprocessor 76 further determines whether the measured leading
phase angle .PHI. is equal to zero (S707). If it is equal to zero,
the microprocessor 76 obtains the current PWM duty (S708). If the
current PWM duty is greater than zero (S709), it reduces the PWM
duty by a predetermined level .beta.. Next, if it determines that
the motor is not stopped (S711), all the previous steps are
repeated again. In addition, if it is determined in step S704 that
the measured DC voltage V is greater than V.sub.c, steps S704 to
S719 are skipped and step S711 is performed.
Embodiment (8)
[0101] FIG. 8A illustrates an apparatus of controlling operation of
a motor in a washer according to an eighth embodiment of the
present invention. Referring to FIG. 8A, the apparatus includes a
key input unit 810 receiving commands from a user for a wash cycle,
a motor 830 rotating a tub and/or an agitator of the washer, and a
controller 820 generating control signals to perform the wash cycle
according to a wash option selected by the user and to lock a wash
door (not illustrated) if the speed of the motor 830 is equal to a
predetermined speed. The apparatus shown in FIG. 8A further
includes a washer door locking unit 850 that locks or unlocks the
washer door of the washer, a speed measuring unit (e.g., a
speedometer) 840 measuring the rotating speed of the motor 830 and
providing the measured speed to the controller 820, and a display
unit 860 that displays a message indicating the locking status of
the washer door upon receiving a control signal from the controller
820.
[0102] When a user inputs commands for a wash cycle through the key
input unit 810, the controller 820 generate control signals to
perform a wash cycle, a rinse cycle, and a spin (dehydration
cycle). After the spin cycle is initiated, the controller 820
generates a control signal to the wash door locking unit 850 to
lock the washer door when the speed of the motor 830 reaches a
first predetermined motor speed. When the speed of the motor
further reaches a second predetermined motor speed, the controller
820 maintains the speed of the motor 830 until the spin cycle is
finished.
[0103] Reference will now be made in detail to a method of
controlling operation of a motor in a washer according to the
eighth embodiment of the present invention. Referring to FIG. 5B,
if the controller 820 determines that a spin cycle (dehydration
cycle) is ordered (S801), it increases the speed W of the motor 830
(S802). Next, if the controller 820 determines that W is equal to a
first predetermined motor speed W.sub.1, e.g., 700 RPM (S803), it
sends a control signal to the washer door locking unit 850 to lock
the washer door of the washer (S804). If W is determined to be less
than W.sub.1 in step S803, the controller 820 repeats step S802
until W becomes W.sub.1. After the washer door is locked in step
S804, the controller 820 further increases the motor speed W
(S805). If it is determined that W has reached a second
predetermined motor speed W.sub.2, e.g., 1000 RPM, which is greater
than W.sub.1 (S806), the controller 820 maintains the motor speed W
until the spin cycle is finished (S807 and S808). As described
above, the controller 820 does not lock the washer door until the
speed of the motor 830 reaches to the first predetermined motor
speed W.sub.1 so that the power consumption and durability of the
door lock are greatly improved.
Embodiment (9)
[0104] FIG. 9A illustrates a control system that drives a motor
provided in a washer according to a ninth embodiment of the present
invention. The motor control system shown in FIG. 9A illustrates a
rectifier 911 rectifying the AC power, a motor 912 rotating a tub
or an agitator of the washer, and a driving circuit 913 comprising
a plurality of insulating gate bipolar transistors (IGBT). The
driving circuit 913 applies input voltages U, V, and W having three
different phases, respectively, to the motor 912 in a first mode
and applies phase-reversed voltages to the motor 912 in a second
mode so that the reverse voltages generated by the motor 912 due to
its rotation are applied to the driving circuit 913.
[0105] The control system shown in FIG. 9A further includes a
switching mode power supply (SMPS) unit 914 transforming the output
of the rectifier 911 into a voltage having a predetermined level
(e.g., 5V), a speedometer 915 measuring the rotational speed of the
motor 912, a braking resistor R.sub.b dissipating the reverse
voltages generated by the motor 912 into heat so as to prevent
possible circuit damages, and a transistor T.sub.1 driving the
braking resistor R.sub.b. The control system further includes a
voltmeter 916 measuring the output voltage of the rectifier 911
after the reverse voltages of the motor 912 are dissipated in
R.sub.b, a microprocessor 917 controlling operations of the driving
circuit 913 and the transistor T.sub.1 on the basis of the output
voltage measured by the voltmeter 916, and a door opening sensor
(not illustrated) detecting opening of a washer door and sending a
corresponding to the microprocessor 917.
[0106] Reference will now be made in detail to a method of
controlling a motor in a washer according to the ninth embodiment
of the present invention, which is illustrated in FIG. 9B.
Referring to FIG. 9B, when a user inputs commands for washing a
load of clothes to be washed, the microprocessor 917 operates the
driving circuit 913 so as to rotate the motor 912 based on a wash
algorithm or program that correspond to the user input commands so
that a tub and an agitator of the washer are rotated for performing
wash and rinse cycles. Thereafter, the microprocessor 917 initiates
a spin (dehydration) cycle by increasing the speed of the motor 912
(S931). The speed of the motor 912 in a spin cycle should be
determined based on a total weight of the load of clothes to be
dehydrated or weight distribution of the load, but is typically
greater than 100 rpm.
[0107] After a spin cycle is initiated in step S931, the
microprocessor 917 determines whether a motor brake is necessary by
determining any one of the conditions for braking motor operation
is met (S932). For example, if a motor interruption command
inputted by a user or a signal indicating opening of a washer door
is received, or if the speed of the motor 912 measured by the
speedometer 915 is determined to be abnormal, the microprocessor
917 determines that interruption (brake) of the motor operation is
necessary. If any one of such conditions is met, the microprocessor
917 determines whether the current speed W of the motor 912 is
greater than a first critical speed W.sub.1 (S933). W.sub.1
(typically set to 1000 rpm) represents the minimum speed of the
motor 912 that can mechanically damage the motor 912 or any other
components that associate with the motor 912 (e.g., a clutch) when
a rapid brake of the motor operation is performed. If it is
determined in step S933 that W is greater than W.sub.1, the
microprocessor 917 controls the driving circuit 913 to short power
input terminals of the motor 912 for a predetermined period of time
in order to brake the motor operation (S934). By doing so, rather a
slow motor brake is achieved so that any mechanical damage due to a
rapid motor brake can be prevented.
[0108] Next, the microprocessor 917 further determines whether the
current speed W of the motor 912 is less than W.sub.1 and is
greater than a second critical speed W.sub.2 (S935). W.sub.2
(typically set to 100 rpm) represents the allowable speed of the
motor 912 that does not create any mechanical damage even if a
rapid brake of the motor operation is performed. If it is
determined in step S935 that W is less than W.sub.1 and is greater
than W.sub.2, then microprocessor 917 performs a rapid motor brake
by operating the driving circuit 913 to apply phase-reversed
voltages to the motor 912 for a predetermined period of time and by
operating the brake resistor R.sub.b so as to dissipate the reverse
voltages generated by the motor 912 during the rapid motor brake
(S936). In the method shown in FIG. 9B, a same rapid brake is
performed when W is in a signal speed range of W.sub.1 to W.sub.2.
However, different rapid brakes can be performed for a plurality of
subdivided ranges of the motor speed by using different duty
rations when applying the phase-reversed voltages to the motor
912.
[0109] Furthermore, the microprocessor 917 further determines
whether the current speed W of the motor 912 is less than W.sub.2
(S937). If it is, the microprocessor 917 controls the driving
circuit 913 to short the power input terminals of the motor 912 in
order to brake the motor operation (S938). Since W is less than 100
rpm, the motor operation can be easily. Thereafter, if the
microprocessor 917 determines that the motor operation is
terminated (S939), then it ends the motor control algorithm.
Otherwise, steps S933 to S939 are repeated.
[0110] Referring back to step S932, if none of the conditions for
braking motor operation are met and if the spin cycle is determined
to be terminated in step S940, the microprocessor 917 ends the
motor control algorithm.
Embodiment (10)
[0111] FIG. 10 illustrates a circuitry for limiting a motor current
in an electrical appliance according to a tenth embodiment of the
present invention. Referring to FIG. 10, the current limiting
circuitry includes a microprocessor 999, a power source V.sub.cc
supplying a source voltage of 5V, a first resistor R (having a
resistance of 33 k and a dip switch 997 connected between the power
source V.sub.cc and a ground in series, a capacitor C.sub.1
connected to the dip switch 997 in parallel, an op amp 998 having
an inverting input connected to a node between R1 and the dip
switch 997 and an output connected to the microprocessor 999, and a
third resistor R.sub.3 having a resistance of 0.027 k, which is
connected between the noninverting input of the op amp 998 and a
ground.
[0112] Reference will now be made in detail to the operation of the
current limiting circuitry shown in FIG. 10. The dip switch 997
comprises a plurality of resistors having different resistances
(e.g., 1.3 k, 1.5 k, 1.8 k, 2.0 k, and so on). Therefore, an
appropriate one of the plurality of resistors can be conveniently
selected for selecting a limited current value. For example, if a
resistor having a resistance of 1.3 k is selected by the dip switch
997, then the limited current that flows through R3 is
I={(5*1.3)/(33.div.1.3)}/0.027=7 A.
[0113] Alternatively, if a resistor having a resistance of 1.8 k is
selected by the dip switch 997, the limited current that flows
through R3 is
I={(5*1.8)/(33.div.1.8)}/0.027=9A.
[0114] As shown in the examples shown above, the value of the
limited current that flows through R3 is varied based on the
switching of the dip switch 997. When more than one resistors are
selected by the dip switch 997, the value of the current that flows
through R3 can be even lower since the selected resistors are in
parallel. Instead of using the dip switch 997, a
resistance-variable resistor can be used. However, it has a
disadvantage that it is difficult to set a precise resistance value
of the resistance-variable resistor.
[0115] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *