U.S. patent application number 13/749989 was filed with the patent office on 2013-08-01 for apparatus and method for controlling a compressor.
The applicant listed for this patent is Gyunam Kim, Boram Lee, Jaeyoo Yoo. Invention is credited to Gyunam Kim, Boram Lee, Jaeyoo Yoo.
Application Number | 20130195613 13/749989 |
Document ID | / |
Family ID | 48870359 |
Filed Date | 2013-08-01 |
United States Patent
Application |
20130195613 |
Kind Code |
A1 |
Kim; Gyunam ; et
al. |
August 1, 2013 |
APPARATUS AND METHOD FOR CONTROLLING A COMPRESSOR
Abstract
An apparatus and method for controlling a compressor are
provided. An input voltage of a commercial power source, a motor
voltage of a compressor motor, and a motor current of the
compressor motor are detected, based on which voltage values of a
capacitor and voltage values of a triac may be calculated. Thus, an
additional operational amplifier or a sensor to measure a capacitor
voltage is not required, reducing costs.
Inventors: |
Kim; Gyunam; (Seoul, KR)
; Yoo; Jaeyoo; (Seoul, KR) ; Lee; Boram;
(Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kim; Gyunam
Yoo; Jaeyoo
Lee; Boram |
Seoul
Seoul
Seoul |
|
KR
KR
KR |
|
|
Family ID: |
48870359 |
Appl. No.: |
13/749989 |
Filed: |
January 25, 2013 |
Current U.S.
Class: |
415/1 ;
415/10 |
Current CPC
Class: |
F04D 15/00 20130101;
F04B 35/045 20130101 |
Class at
Publication: |
415/1 ;
415/10 |
International
Class: |
F04D 15/00 20060101
F04D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2012 |
KR |
10-2012-0009078 |
Claims
1. An apparatus for controlling a compressor, the apparatus
comprising: one or more capacitors connected to a compressor motor;
a triac that operates the compressor motor according to a gate
driving signal; and a microcomputer that generates the gate driving
signal, and calculates voltage values of the one or more capacitors
and the triac using an input voltage of a commercial power source,
a motor voltage of the compressor motor, and a motor current of the
compressor motor.
2. The apparatus of claim 1, wherein the microcomputer includes a
capacitor voltage calculator that calculates voltage values of the
capacitor, wherein when the motor current is 0, the capacitor
voltage calculator calculates a predetermined capacitor voltage
value.
3. The apparatus of claim 1, wherein the microcomputer includes a
capacitor voltage calculator that calculates voltage values of the
capacitor, wherein when a value of the motor current is not 0, the
capacitor voltage calculator calculates a value obtained by
subtracting the motor voltage from the input voltage, as a voltage
value of the capacitor.
4. The apparatus of claim 2, wherein the microcomputer includes a
triac voltage calculator that calculates triac voltage values using
the input voltage, the motor voltage, and the capacitor voltage
value.
5. The apparatus of claim 4, wherein the triac voltage calculator
subtracts a value of the motor voltage from a value of the input
voltage, and subtracts the capacitor voltage value from the
resultant subtraction value to calculate the triac voltage
values.
6. The apparatus of claim 1, further comprising: an input voltage
detector that detects an input voltage of the commercial power
source; a motor voltage detector that detects a motor voltage
applied to the compressor motor; and a motor current detector that
detects a motor current flowing in the compressor motor.
7. The apparatus of claim 7, further comprising: a zero voltage
detector that detects a zero voltage from the detected input
voltage.
8. The apparatus of claim 1, further comprising: a commercial power
source that supplies power to the compressor motor; and a
rectifyier that rectifies and smooths the power provided from the
commercial power source.
9. The apparatus of claim 1, further comprising: a switch connected
to the triac, the switch connecting the triac to the compressor
motor or directly connecting the commercial power source to the
compressor motor according to a control signal.
10. The apparatus of claim 9, wherein the microcomputer generates
the control signal for controlling an operation of the switch and
provides the generated control signal to the switch.
11. The apparatus of claim 1, wherein the compressor comprises a
reciprocating compressor.
12. A method for controlling a compressor, the method comprising:
detecting an input voltage of a commercial power source, a motor
voltage of a compressor motor, and a motor current of the
compressor motor; calculating a voltage of a capacitor connected to
the compressor motor using the input voltage, the motor voltage,
and the motor current; calculating a voltage of a triac operating
the compressor motor according to a gate driving signal using the
calculated capacitor voltage; and controlling the compressor using
the detected input voltage, the motor voltage, and the motor
current, and the calculated voltages of the capacitor and the
triac.
13. The method of claim 12, wherein in the calculating of the
voltage of the capacitor, when the motor current is 0, a
predetermined voltage is calculated.
14. The method of claim 12, wherein in the calculating of the
voltage of the capacitor, when the motor current is not 0, a
voltage value obtained by subtracting the motor voltage from the
input voltage is calculated.
15. The method of claim 12, wherein in the calculating of the
voltage of the triac, a value is obtained by subtracting the motor
voltage from the input voltage, and the calculated voltage of the
capacitor is subtracted from the obtained value to calculate the
voltage of the triac.
16. The method of claim 12, further comprising: detecting whether
the compressor has an error by monitoring the motor voltage, the
capacitor voltage, and the triac voltage.
17. The method of claim 12, wherein the compressor comprises a
reciprocating compressor.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] Pursuant to 35 U.S.C. .sctn.119(a), this application
priority to Korean Application No. 10-2012-0009078, filed on Jan.
30, 2012, the contents of which is incorporated by reference herein
in its entirety.
BACKGROUND
[0002] 1. Field
[0003] An apparatus for controlling a compressor and a method for
controlling a compressor are disclosed herein.
[0004] 2. Background
[0005] Apparatuses and methods for controlling a compressor are
known. However, they suffer from various disadvantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Embodiments will be described in detail with reference to
the following drawings in which like reference numerals refer to
like elements, and wherein:
[0007] FIG. 1 is a graph showing capacitor voltage calculation
values of a capacitor of an apparatus for controlling a compressor
according to an embodiment;
[0008] FIG. 2 is a graph showing triac voltage calculation values
of a triac of the apparatus for controlling a compressor according
to an embodiment;
[0009] FIG. 3 is a schematic diagram of an apparatus for
controlling a compressor according to an embodiment;
[0010] FIG. 4 is a flow chart of a method for controlling a
compressor according to an embodiment;
[0011] FIG. 5 is a cross-sectional view of a reciprocating
compressor included in an apparatus for controlling a compressor
according to embodiments; and
[0012] FIG. 6 is a perspective view of a refrigerator employing the
reciprocating compressor of FIG. 5.
DETAILED DESCRIPTION
[0013] Description will now be given in detail of embodiments, with
reference to the accompanying drawings. For the sake of brief
description with reference to the drawings, the same or equivalent
components will be provided with the same reference numbers, and
description thereof will not be repeated.
[0014] In general, a compressor, a device that converts mechanical
energy into compression energy, may be used as part of
refrigeration equipment, for example, a refrigerator, or an
air-conditioner. A compressor may be classified as a reciprocating
compressor, a rotary compressor, or a scroll compressor. In the
reciprocating compressor, a compression space, into or from which
an operating gas is sucked or discharged, is formed between a
piston and a cylinder, and a piston linearly reciprocates within a
cylinder to compressor a refrigerant. In the rotary compressor, a
compression space, into or from which an operating gas is sucked or
discharged, is formed between an eccentrically rotating roller and
a cylinder, and the roller eccentrically rotates along an inner
wall of the cylinder to compress a refrigerant. In the scroll
compressor, a compression space, into or from which an operating
gas is sucked or discharged, is formed between an orbiting scroll
and a fixed scroll, and the orbiting scroll rotates along the fixed
scroll to compress a refrigerant.
[0015] In general, a reciprocating compressor, in which a piston
linear reciprocates within a cylinder to suck, compress, and
discharge a refrigerant gas, is classified as a recipro compressor
and a linear compressor according to a method of driving a piston.
The recipro compressor is a reciprocating compressor, in which a
crank shaft is coupled to a rotary motor and a piston is coupled to
the crank shaft to change rotatory power of the rotary motor into a
linear reciprocal movement. The linear compressor is a
reciprocating compressor, in which a piston is directly connected
to a mover of a linear motor to reciprocate a piston by a linear
motion of the motor.
[0016] As described above, the linear compressor does not employ a
crank shaft to convert a rotational motion to a linear motion,
causing less frictional loss, so its performance is excellent
relative to a general compressor in terms of compression
efficiency. The linear compressor may be used in a refrigerator or
an air-conditioner, to vary a voltage applied to a compressor to
control freezing capacity.
[0017] In the linear compressor, in order to improve a usage rate
of an applied voltage, an AC capacitor may be connected in series
to configure an apparatus for controlling a compressor. Also, the
apparatus for controlling a compressor generally detects a motor
voltage and a motor current of a compressor motor, calculates a
stroke, and controls a compressor based on the stroke. However, in
the apparatus for controlling a compressor, in order to protect a
compressor against, for example, an overload in controlling the
compressor, voltage values of a capacitor and a triac connected to
the compressor should be continuously or periodically detected.
However, additional installation of a new operational amplifier
(OPAMP) in order to continuously or periodically detect the voltage
values increases costs. An apparatus for controlling a compressor
according to an embodiment may include one or more capacitors
connected to a compressor motor, a triac that operates the
compressor motor according to a gate driving signal, and a
microcomputer that generates the gate driving signal, and
calculates voltage values of the capacitors and the triac using
values of an input voltage of a commercial power source, a motor
voltage of the compressor motor, and a motor current of the
compressor motor.
[0018] Hereinafter, an apparatus for controlling a compressor and a
method for controlling a compressor according to embodiments will
be described in detail with reference to the accompanying
drawings.
[0019] First, a reciprocating compressor applied to embodiments
will be described in detail with reference to FIG. 5. The
reciprocating compressor 100 of FIG. 5 may include a casing 800, to
which a gas suction pipe SP and a gas discharge pipe DP may be
connected, a frame 200 elastically supported within the casing 800,
a motor 300 supported by the frame 200 and having a mover 330 that
linearly reciprocates, a compression device 400 having a piston 420
coupled to the mover 330 of the motor 300 and supported by the
frame 200, and a plurality of resonance devices 500 that
elastically supports the mover 330 of the motor 300 and the piston
420 of the compression device 400 in a motion direction to induce a
resonant movement.
[0020] The frame 200 may include a first frame 210 that supports
the compression device 400 and a front side of the motor 300, a
second frame 220 coupled to the first frame 210 that supports a
rear side of the motor 300, and a third frame 230 coupled to the
second frame 220 that supports a plurality of second resonance
springs 530. The first frame 210, the second frame 220, and the
third frame 230 may be made of a non-magnetic material, such as
aluminum, to reduce iron loss.
[0021] The first frame 210 may include a frame part 211 formed to
have an annular plate shape, and a cylinder part 212 having a
cylindrical shape integrally formed to extend to a rear side,
namely, toward the motor, such that a cylinder 410 may be inserted
at a center of the frame part 211. The frame part 211 may be formed
such that an outer diameter thereof is not at least smaller than an
inner diameter of an outer stator 310 of the motor 300 in order to
support both the outer stator 310 and an inner stator 320 of the
motor 300.
[0022] The inner stator 320 may be insertedly fixed to an outer
circumferential surface of the cylinder part 212. The first frame
210 may be made of a non-magnetic material, such as aluminum, to
prevent a loss of magnetic force. The cylinder part 212 may be
integrally formed in the cylinder 410 by, for example, an
insert-dicasting technique. However, the cylinder 410 may be
press-fit to an inner circumferential surface of the cylinder part
212, or the inner circumferential surface of the cylinder part 212
may be threaded to screw-assemble the cylinder 410. The cylinder
part 212 may have a step surface or a sloped surface between a
front inner circumferential surface and a rear inner
circumferential surface to allow the cylinder 410 coupled to the
inner circumferential surface of the cylinder part 212 to be
supported in the direction of the piston, and this may be
advantageous in terms of stability of the cylinder 410.
[0023] The motor 300 may include the outer stator 310, which may be
supported between the first frame 210 and the second frame 220 and
have a coil 311 wound therearound, the inner stator 320 coupled to
an inner side of the outer stator 310 with a certain gap
therebetween and insertedly positioned on the cylinder part 212,
and a mover 330 including a magnet 331 corresponding to the coil
311 of the outer stator 310 and making a linear reciprocal movement
in a magnetic flux direction between the outer stator 310 and the
inner stator 320. The outer stator 310 and the inner stator 320 may
be formed, for example, by laminating a plurality of sheets of thin
stator cores to have a cylindrical shape or by laminating a
plurality of sheets of thin stator cores to have a block shape and
radially laminating the stator blocks.
[0024] The compression device 400 may include the cylinder 410,
which may be integrally formed with the first frame 210, the piston
420 coupled to the mover 330 of the motor 300 that makes a
reciprocal movement in a compression space P of the cylinder 410, a
suction valve 430 installed on a front end of the piston 420 that
adjusts suction of a refrigerant gas by opening and closing a
suction flow path 421 of the piston 420, a discharge valve 440
installed at a discharge side of the cylinder 410 that adjusts
discharging of a compression gas by opening and closing the
compression space P of the cylinder 410, a valve spring 450 that
elastically supports the discharge valve 440, and a discharge cover
460 fixed to the first frame 210 at the discharge side of the
cylinder 410 such that the discharge valve 440 and the valve spring
450 are accommodated.
[0025] The cylinder 410 may have a cylindrical shape and be
insertedly coupled to the cylinder part 212 of the first frame 210.
The cylinder 410 may form a bearing surface with the piston 420
having an inner circumferential surface made of, for example, cast
iron, and in order to avoid abrasion of the cylinder 410 by the
piston 420, the cylinder 410 may be made of a material having a
higher hardness than that of the first frame 210, more
specifically, the cylinder part 212.
[0026] The piston 420 may be made of the same material as that of
the cylinder 410 or may be made of a material having a hardness
which is at least similar to that of the cylinder 410 to reduce
abrasion with the cylinder 410. The suction flow path 421 may be
formed to penetrate an interior of the piston 420 to allow a
refrigerant to be sucked into the compression chamber P of the
cylinder 410.
[0027] The resonance device 500 may include a spring supporter 510
coupled to a connection portion of the mover 330 and the piston
420, first resonance springs 520 supported by a front side of the
spring supporter 510, and second resonance springs 530 supported by
a rear side of the spring supporter 510.
[0028] Reference numeral 422 denotes a piston connection portion
and reference numeral 600 denotes an oil feeder.
[0029] When power is applied to the motor 300 and magnetic flux is
formed between the outer stator 310 and the inner stator 320, the
mover 330 placed in an air gap between the outer stator 310 and the
inner stator 320 may move in a direction of the magnetic flux and
continuously makes a reciprocal movement by the resonance device
500. When the piston 420 makes a backward movement within the
cylinder 410, a refrigerant filled in the internal space of the
casing 800 may be sucked into the compression space P of the
cylinder 410 through the suction flow path 421 of the piston 420
and the suction valve 430. When the piston 420 makes a forward
movement within the cylinder 410, the refrigerant gas sucked into
the compression space P may be compressed and open the discharge
valve 440 so as to be discharged. This sequential process may be
repeatedly performed.
[0030] The reciprocating compressor according to embodiments may
include an apparatus for controlling a compressor as follows. Also,
the reciprocating compressor may be used in refrigeration
equipment, such as a refrigerator or an air-conditioner. For
example, referring to FIG. 6, in a refrigeration equipment 700
having a refrigerant compression type refrigerating cycle including
a compressor, a condenser, an expander, and an evaporator, a main
board 710 that controls a general operation of the refrigeration
equipment 700 may be provided and the reciprocating compressor C
may be connected to the main board 710. The apparatus for
controlling a compressor may be provided in the main board 710.
[0031] Hereinafter, an apparatus for controlling a compressor,
which may include the reciprocating compressor 100 as described
above, according to embodiments, will be described in detail with
reference to FIG. 3. As illustrated, the apparatus for controlling
a compressor may include a commercial power source 10, a triac 20,
a compressor 30 (100), an alternating current (AC) capacitor 40,
and a microcomputer 90. The apparatus for controlling a compressor
may further include an input voltage detector 50, a motor voltage
detector 60, a zero voltage detector 70, and a motor current
detector 80. However, such a configuration may vary as
necessary.
[0032] The commercial power source 10 may supply power to the
compressor 30. Upon receiving power from the commercial power
source 10, the compressor 30 may perform a reciprocal movement of a
piston. The commercial power 10 may be, for example, AC power of
220V which is generally used in households.
[0033] The triac 20 may operate the motor of the compressor 30
according to a gate driving signal. In more detail, the triac 20
may be connected in series to the compressor 30 and operate the
compressor 30 according to a gate driving signal received from the
microcomputer 90. In one embodiment, in preparation for a
malfunction due to abnormal driving, the triac 20 may include a
switch, for example, a triac protection relay (not shown), that
protects the triac 20.
[0034] The capacitor 40 may be connected to a motor of the
compressor 30, and may have a capacitance corresponding to an
inductance of a coil wound around the motor of the compressor 30.
As the capacitor 40, an AC capacitor may be used; however,
embodiments are not limited thereto.
[0035] The microcomputer 90 may calculate voltage values of the
capacitor 40 and the triac 20 using values of an input voltage of
the commercial power source 10, a motor voltage of the motor of the
compressor 30, and a motor current of the motor of the compressor
30. Also, the microcomputer 90 may generate a gate driving signal
for controlling ON/OFF of the triac 20.
[0036] The microcomputer 90 may include a capacitor voltage
calculator 92 that calculates voltage values of the capacitor 40
and a triac voltage calculator 94 that calculates voltage values of
the triac 20. Thus, the apparatus for controlling a compressor
according to an embodiment does not need to include an extra sensor
or an additional operational amplifier (OPAMP) to detect the
voltage of the capacitor 40 and the voltage of the triac 20.
[0037] First, relationships among the input voltage, the motor
voltage, the capacitor voltage, and the triac voltage may be
represented by Equation 1 below from a general motor equation.
V m = Ri m + L i m t + K x t V i n = V m + V cap + V triac , ( V
cap = 1 C .intg. i m t ) [ Equation 1 ] ##EQU00001##
[0038] Here, Vin is an input voltage of the commercial power
source, Vm is a motor voltage, Vcap is a voltage of the capacitor,
and Vtriac is a voltage of the triac. Also, i is a motor current
flowing in the compressor motor, R is internal resistance of the
compressor, L is inductance of a motor coil, K is a motor constant,
and C is capacitance forming a resonance circuit together with
L.
[0039] When the value of the motor current flowing in the
compressor motor is 0, the capacitor voltage calculator 92 may
calculate a predetermined value as a capacitor voltage value.
Namely, in a section of a motor current waveform in which the motor
current value is 0, there is no change in the capacitor voltage
value. Thus, in the section of the motor current waveform in which
the motor current value is 0, there is no change in the capacitor
voltage value. Also, when the value of the motor current flowing in
the compressor motor is not 0, the capacitor voltage calculator 92
may calculate a value obtained by subtracting the motor voltage
from the input voltage, as a capacitor voltage value.
[0040] A graph including capacitor voltage values calculated by the
capacitor voltage calculator 92 is illustrated in FIG. 1. As
illustrated in FIG. 1, waveforms of the input voltage, the motor
voltage, and the motor current detected through one or more sensors
are illustrated. The capacitor voltage values are derived using the
detected input voltage, motor voltage, and the motor current
values. The capacitor voltage value may be derived from Equation 1
as follows.
Vcap(k)=Vin(k)-Vm(k)-Vtriac(k)
[0041] Equation 2 below may be derived using the fact that when the
value of the current flowing in the motor of the compressor 30 is
not 0, the voltage of the triac 20 is 0.
V cap(k)=Vin(k)-Vm(k) [Equation 2]
[0042] Also, Equation 3 below may be derived using the fact that
when the current value flowing in the motor of the compressor 30 is
not 0, there is no change in the voltage of the capacitor 40.
V cap(k)=Vcap(k-1) [Equation 3]
[0043] Referring to FIG. 1, as the current value flowing in the
motor of the compressor 30 in a first region illustrated in FIG. 1
is not 0, a capacitor voltage value is calculated by Equation 2.
Namely, in this case, a result value obtained by subtracting a
voltage value applied to the motor of the compressor 30 from the
input voltage value of the commercial power source 10 is calculated
as a capacitor voltage value.
[0044] Also, as the current value flowing in the motor of the
compressor 30 in a second region shown in FIG. 1 is 0, a capacitor
voltage value is calculated by Equation 3. Namely, in this section,
there is no change in the capacitor voltage value in the second
section and a predetermined value is calculated as a capacitor
voltage value.
[0045] The current value flowing in the motor of the compressor 30
may be 0 during a predetermined region or at a particular vertex.
In any event, the capacitor voltage value is calculated by Equation
3. For example, when the motor current value flowing in the motor
of the compressor 30 during the predetermined region is 0, it means
that a capacitor voltage value is maintained as a predetermined
value in the corresponding section, and when the motor current
value flowing in the motor of the compressor 30 is 0 at a
particular vertex, it means that the capacitor voltage value at the
vertex has the same value as that of an immediately previous
capacitor voltage value.
[0046] The triac voltage calculator 94 may calculate a triac
voltage value using the input voltage, the motor voltage, and the
capacitor voltage value calculated by the capacitor voltage
calculator 92. The triac voltage calculator 94 may subtract the
motor voltage from the input voltage to obtain a value, and
subtract the capacitor voltage value from the obtained value to
calculate the triac voltage value. Namely, the triac voltage value
may be calculated by Equation 4 derived from Equation 1.
Vtriac(k)=Vin(k)-Vm(k)-Vcap(k) [Equation 4]
[0047] A graph including triac voltage values calculated by the
triac voltage calculator 94 is illustrated in FIG. 2. As
illustrated in FIG. 2, waveforms of the input voltage and the motor
voltage detected through one or more sensors and the capacitor
voltage calculated by the capacitor voltage calculator 92 are
illustrated. The triac voltage values are calculated using the
detected input voltage, the motor voltage, and the calculated
capacitor voltage values. As illustrated, in the first region shown
in FIG. 1, namely, in the section in which a current value flowing
in the motor of the compressor 30 is not 0, the triac voltage value
is 0. Meanwhile, in a section in which the current value flowing in
the motor of the compressor 30 is 0, the triac voltage value is
calculated by Equation 4.
[0048] Also, the microcomputer 90 may generate a gate driving
signal of the triac 20 and transfer the generated gate driving
signal to control a stroke of the compressor 30.
[0049] The input voltage detector 50 may detect an input voltage of
the commercial power source 10. The input voltage detector 50 may
check for a change in voltage.
[0050] The motor voltage detector 60 may detect a motor voltage
applied to the motor of the compressor 30. The motor current
detector 80 may detect a motor current flowing in the motor of the
compressor 30. A stroke for controlling the compressor 30 may be
calculated from the motor voltage detected by the motor voltage
detector 60 and the motor current detected by the motor current
detection unit 80. Also, the motor current detector 80 may be, for
example, a current transformer (CT).
[0051] The zero voltage detector 70 may detect a zero voltage from
the input voltage detected by the input voltage detector 50. The
zero voltage detector 70 may check for a change in frequency.
[0052] Also, the apparatus for controlling a compressor may further
include a switch (not shown) connected to the triac 20 that
operates to connect the triac 20 to the motor of the compressor 30
or directly connects the commercial power source 10 to the motor of
the compressor 30 according to a control signal. The switch (not
shown) may be a protection relay to protect the triac 20.
[0053] In addition, the apparatus for controlling a compressor may
further include a rectifier (not shown) that rectifies and/or
smooths the power from the commercial power source 10 and supplies
the same to the motor of the compressor 30.
[0054] In the case of the apparatus for controlling a compressor
and the method for controlling a compressor according to
embodiments, without using a voltage sensor to detect a capacitor
voltage and a triac voltage, the capacitor voltage and the triac
voltage may be calculated using an input voltage value of the
commercial power source, a motor voltage value of the compressor
motor, and a motor current value of the compressor motor. Thus, the
calculation may be easily performed and an additional operational
amplifier (OPAMP) or an extra sensor is not required to be
used.
[0055] A method for controlling a compressor according to
embodiments will be described in detail with reference to FIGS. 3
and 4.
[0056] In general, in a reciprocating compressor, a piston may move
vertically by an application voltage according to a stroke
reference value set by a user, and thus, a stroke is varied to
regulate freezing capacity. The triac 20 may increase the stroke by
lengthening a turn-on period of gate driving or reduce the stroke
by shortening the turn-on period of gate driving according to a
switching control signal transferred from the microcomputer 90.
[0057] In the method for controlling a compressor according to an
embodiment, for example, an input voltage of a commercial power
source, a motor voltage of the compressor motor, and a motor
current of the compressor motor may be detected using, for example,
a sensor or an operational amplifier (OPAMP), in step S10. In more
detail, the motor voltage detector 60 and the motor current
detector 80 may detect a voltage and a current applied to the motor
of the compressor 30 and apply the same to the microcomputer
90.
[0058] Thereafter, a capacitor voltage of the capacitor connected
to the compressor motor may be calculated using the detected input
voltage, the motor voltage, and the motor current values, in step
S20. When the detected motor current value is 0, the capacitor
voltage may be calculated as a predetermined voltage value. Namely,
while the detected motor current value is 0, there is no change in
the capacitor voltage value. When the detection motor current value
is not 0, a voltage value of the capacitor may be calculated by
subtracting a corresponding motor voltage value from the detected
input voltage value. That is, while the detected motor current
value is not 0, the capacitor voltage value may be calculated from
a difference between the input voltage and the motor voltage value.
Thereafter, a triac voltage value of the triac operating the
compressor motor may be calculated according to a gate driving
signal by using the calculated capacitor voltage values, in step
S30.
[0059] The microcomputer 90 may calculate a stroke of the
compressor 30 using the voltage and the current detected by the
motor voltage detector 60 and the motor current detector 80.
Thereafter, the microcomputer 90 may compare the calculated stroke
with a predetermined stroke command, and output a switching control
signal for switching the triac 20 based on the comparison
result.
[0060] When the stroke is smaller than the stroke command value,
the microcomputer 90 may output a switching control signal for
lengthening an ON period of the triac 20 to increase a voltage
applied to the motor of the compressor 30. That is, when the
calculated stroke is smaller than the stroke command value, the
microcomputer 90 may change the calculated voltage value of the
triac 20 in order to increase a firing angle of the switching
control signal. Meanwhile, when the calculated stroke is greater
than the stroke reference value, the microcomputer 90 may change
the calculated voltage value in order to reduce the firing angle of
the switching control signal.
[0061] In other words, the stroke may be calculated using the motor
voltage and the motor current, and the calculated stroke may be
compared with the stroke reference value to increase or decrease
the firing angle of the triac, thus changing the calculated voltage
value of the triac. Namely, the triac may be turned on during a
predetermined turn-on time of the triac and generate a motor
voltage corresponding to a desired stroke. Also, the triac may be
maintained in the ON state during a predetermined connection time
interval of the triac, and then turned off.
[0062] In this manner, the process of calculating a voltage value
of the triac for controlling the compressor may include subtracting
the motor voltage from the input voltage to obtain a value, and
subtracting the capacitor voltage value calculated in step S20 from
the obtained value. In this manner, in the method for controlling a
compressor according to embodiments, the capacitor voltage value
and the triac voltage value required for controlling a compressor
may be calculated using the input voltage of the commercial power,
the motor voltage of the compressor motor, and the motor current of
the compressor motor, without using an extra sensor.
[0063] Also, in embodiments disclosed herein, the motor voltage,
the calculated voltage value of the capacitor, and the voltage
value of the triac may be monitored at predetermined time
intervals, to determine whether there is an error in driving the
compressor. Also, while monitoring the detected or calculated
voltage values, when an error of the input voltage of the
commercial power source applied to the compressor motor is
detected, at least one of the voltages among the motor voltage, the
capacitor voltage, and the triac voltage may be changed
accordingly.
[0064] As described above, in the case of the apparatus for
controlling a compressor and the method for controlling a
compressor according to embodiments, a capacitor voltage and a
triac voltage required for protecting a capacitor and a triac may
be calculated using an input voltage of the commercial power
source, a motor voltage of the compressor motor, and a motor
current of the compressor motor without using a sensor. Thus,
voltage values of the capacitor and the triac may be easily
calculated and an additional operational amplifier (OPAMP) or an
extra sensor is not required, reducing production costs.
[0065] Embodiments disclosed herein provide an apparatus for
controlling a compressor capable of detecting (or calculating) a
capacitor voltage and a triac voltage, which are required to
protect a compressor in an abnormal state, such as, for example, an
overload state, in controlling a compressor, using an input voltage
of commercial power source, a motor voltage of a compressor motor,
and a motor current of a compressor motor detected by a
predetermined unit, without using a sensor.
[0066] Embodiments disclosed herein provide an apparatus for
controlling a compressor that may include one or more capacitors
connected to a compressor motor; a triac that operates the
compressor motor according to a gate driving signal; and a
microcomputer that generates the gate driving signal, and
calculates voltage values of the capacitors and the triac using
values of an input voltage of a commercial power source, a motor
voltage of the compressor motor, and a motor current of the
compressor motor.
[0067] The microcomputer may include a capacitor voltage
calculation unit or calculator that calculates a voltage value of
the capacitor, and when the motor current value is 0, the capacitor
voltage calculation unit may calculate a predetermined capacitor
voltage value. The microcomputer may include a capacitor voltage
calculation unit that calculates a voltage value of the capacitor,
and when the motor current value is not 0, the capacitor voltage
calculation unit may calculate a value obtained by subtracting the
motor voltage from the input voltage, as a voltage value of the
capacitor.
[0068] The microcomputer may include a triac voltage calculation
unit or calculator that calculates a triac voltage value using the
input voltage, the motor voltage, and the capacitor voltage value.
The triac voltage calculation unit may subtract the motor voltage
from the input voltage, and subtract the capacitor voltage value
from the resultant subtraction value to calculate the triac voltage
value.
[0069] The apparatus may further include an input voltage detection
unit or detector that detects an input voltage of the commercial
power source; a motor voltage detection unit or detector that
detects a motor voltage applied to the compressor motor, and a
motor current detection unit or detector that detects a motor
current flowing in the compressor motor. The apparatus may further
include a zero voltage detection unit or detector that detects a
zero voltage from the detected input voltage. The apparatus may
further include a commercial power source that supplies power to
the compressor motor, and a rectifying unit or rectifyier that
rectifies and smooths the power provided from the commercial power
source. The apparatus may additionally include a switching unit or
switch connected to the triac and connecting the triac to the
compressor motor or directly connecting the commercial power source
to the compressor motor according to a control signal. The
microcomputer may generate the control signal for controlling an
operation of the switching unit and provide the generated control
signal to the switching unit.
[0070] Embodiments disclosed herein provide a method for
controlling a compressor that may include detecting an input
voltage of a commercial power source, a motor voltage of a
compressor motor, and a motor current of the compressor motor;
calculating a voltage of a capacitor connected to the compressor
motor using the input voltage, the motor voltage, and the motor
current; calculating a voltage of a triac operating the compressor
motor according to a gate driving signal using the calculated
capacitor voltage; and controlling the compressor using the
detected input voltage, the motor voltage, and the motor current,
and the calculated voltage of the capacitor and the voltage of the
triac.
[0071] In the calculating of the voltage of the capacitor, when the
motor current value is 0, a predetermined voltage value may be
calculated. Further, in the calculating of the voltage of the
capacitor, when the motor current value is not 0, a value obtained
by subtracting the motor voltage from the input voltage may be
calculated. In the calculating of the voltage of the triac, a value
may be obtained by subtracting the motor voltage from the input
voltage, and the calculated voltage of the capacitor may be
subtracted from the obtained value to calculate the voltage of the
triac. The method may further include detecting whether the
compressor has an error by monitoring the values of the motor
voltage, the capacitor voltage and the triac voltage.
[0072] In the case of the apparatus and method for controlling a
compressor according to embodiments, the capacitor voltage and the
triac voltage required for protecting a compressor may be detected
using an input voltage of a commercial power source, a motor
voltage of the compressor motor, and the motor current of the
compressor motor. Thus, the calculation may be easily performed,
and an additional operational amplifier or an extra sensor to
measure the capacitor voltage may not be required, reducing
costs.
[0073] Any reference in this specification to "one embodiment," "an
embodiment," "example embodiment," etc., means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
invention. The appearances of such phrases in various places in the
specification are not necessarily all referring to the same
embodiment. Further, when a particular feature, structure, or
characteristic is described in connection with any embodiment, it
is submitted that it is within the purview of one skilled in the
art to effect such feature, structure, or characteristic in
connection with other ones of the embodiments.
[0074] Although embodiments have been described with reference to a
number of illustrative embodiments thereof, it should be understood
that numerous other modifications and embodiments can be devised by
those skilled in the art that will fall within the spirit and scope
of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts
and/or arrangements of the subject combination arrangement within
the scope of the disclosure, the drawings and the appended claims.
In addition to variations and modifications in the component parts
and/or arrangements, alternative uses will also be apparent to
those skilled in the art.
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