U.S. patent application number 13/626815 was filed with the patent office on 2013-04-04 for cooling fan control device and control method thereof.
This patent application is currently assigned to SAMSUNG ELECTRO-MECHANICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Kyoung Ho Lee.
Application Number | 20130084192 13/626815 |
Document ID | / |
Family ID | 47992754 |
Filed Date | 2013-04-04 |
United States Patent
Application |
20130084192 |
Kind Code |
A1 |
Lee; Kyoung Ho |
April 4, 2013 |
COOLING FAN CONTROL DEVICE AND CONTROL METHOD THEREOF
Abstract
Disclosed herein are a cooling fan driving control device and a
control method thereof non-linearly controlled to a duty ratio (%)
of a PWM signal. The cooling fan driving control device includes a
cooling fan control device including a temperature sensor, a
microprocessor unit generating a PWM signal corresponding to a
temperature measured by the temperature sensor, and a cooling fan
driving unit driving the cooling fan according to a duty ratio of
the PWM signal, comprising: a duty ratio detection unit receiving
the PWM signal from the microprocessor unit to detect the duty
ratio (%) of the PWM signal; and a duty ratio control device
comparing the duty ratio (%) detected from the duty ratio detection
unit with a predetermined threshold value, controlling the duty
ratio (%) of the PWM signal according to the comparison results,
and then, outputting the controlled PWM signal to the cooling fan
driving unit.
Inventors: |
Lee; Kyoung Ho;
(Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRO-MECHANICS CO., LTD.; |
Gyunggi-do |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRO-MECHANICS CO.,
LTD.
Gyunggi-do
KR
|
Family ID: |
47992754 |
Appl. No.: |
13/626815 |
Filed: |
September 25, 2012 |
Current U.S.
Class: |
417/32 |
Current CPC
Class: |
F04D 25/08 20130101;
F04D 27/004 20130101 |
Class at
Publication: |
417/32 |
International
Class: |
F04B 49/10 20060101
F04B049/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2011 |
KR |
2011-0100215 |
Claims
1. A cooling fan control device including a temperature sensor, a
microprocessor unit generating a PWM signal corresponding to a
temperature measured by the temperature sensor, and a cooling fan
driving unit driving the cooling fan according to a duty ratio of
the PWM signal, comprising: a duty ratio detection unit receiving
the PWM signal from the microprocessor unit to detect the duty
ratio (%) of the PWM signal; and a duty ratio control device
comparing the duty ratio (%) detected from the duty ratio detection
unit with a predetermined threshold value, controlling the duty
ratio (%) of the PWM signal according to the comparison results,
and then, outputting the controlled PWM signal to the cooling fan
driving unit.
2. The cooling fan control device according to claim 1, wherein the
duty ratio control device controls the duty ratio (%) of the PWM
signal by comparing the duty ratio (%) detected from the duty ratio
detection unit with the predetermined threshold value and adding
and subtracting the predetermined duty ratio control value to and
from the detected duty ratio (%) of the PWM signal according to the
comparison results.
3. The cooling fan control device according to claim 1, wherein the
duty control device adds the duty ratio control value to the
detected duty ratio (%) of the PWM signal when the duty ratio (%)
detected from the duty ratio detection unit is a predetermined
first threshold value or more; and subtracts the duty ratio control
value from the detected duty ratio (%) of the PWM signal when the
duty ratio (%) detected from the duty ratio detection unit is a
predetermined second threshold value or less, the first threshold
value being larger than the second threshold value.
4. The cooling fan control device according to claim 3, wherein the
first threshold value is any one of 70% to 90%, the second
threshold value is any one of 10% to 30%, and the duty ratio
control value is any one of 1% to 10%.
5. The cooling fan control device according to claim 1, further
comprising a PWM signal generation unit generating a new PWM signal
by receiving the PWM signal from the duty ratio control device and
changing a frequency of the PWM signal according to a predetermined
frequency value.
6. The cooling fan control device according to claim 5, wherein the
PWM signal generation unit performs a function of setting the duty
ratio (%) of the PWM signal to a lowest threshold value when the
duty ratio (%) of the PWM signal received from the duty ratio
control device is a predetermined lowest threshold value or
less.
7. A cooling fan speed control method, comprising: (a) receiving a
PWM signal generated corresponding to temperature measured by a
temperature sensor; (b) detecting a duty ratio (%) of the PWM
signal; (c) comparing the duty ratio (%) detected at the detecting
of the duty ratio with a predetermined first threshold value; (d)
when the duty ratio (%) detected at the comparing of the duty ratio
is below the predetermined first threshold value, comparing it with
the predetermined second threshold value; and (e) generating a new
PWM signal by changing the frequency of the PWM signal according to
the predetermined frequency value when the duty ratio (%) exceeds
the predetermined second threshold value at the comparing of the
duty ratio (%), wherein the first threshold value is larger than
the second threshold value.
8. The cooling fan speed control method according to claim 7,
further comprising: at the comparing of the duty ratio, when the
detected duty ratio (%) is the predetermined first threshold value
or more, adding the predetermined duty ratio control value to the
detected duty ratio (%) of the PWM signal; and generating a new PWM
signal by changing a frequency of the controlled PWM signal
according to a predetermined frequency value.
9. The cooling fan speed control method according to claim 7,
further comprising: at the comparing, when the detected duty ratio
(%) is the predetermined second threshold value or less,
subtracting the predetermined duty ratio control value from the
detected duty ratio (%) of the PWM signal; comparing the controlled
duty ratio (%) of the PWM signal with a lowest threshold value; and
generating a new PWM signal by changing the fixed frequency of the
PWM signal according to the predetermined frequency value when the
controlled duty ratio (%) of the PWM signal exceeds the lowest
threshold value.
10. The cooling fan speed control method according to claim 9,
further comprising: fixing the controlled duty ratio (%) of the PWM
signal to a lowest threshold value when the controlled duty ratio
(%) of the PWM signal is the lowest threshold value; and generating
the new PWM signal by changing the controlled frequency of the PWM
signal according to the predetermined frequency value.
Description
CROSS REFERENCE(S) TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C. Section
119 of Korean Patent Application Serial No. 10-2011-0100215,
entitled "Cooling Fan Control Device And Control Method Thereof"
filed on Sep. 30, 2011, which is hereby incorporated by reference
in its entirety into this application.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to a cooling fan control
device and a control method thereof, and more particularly, to a
cooling fan control device and a control method thereof capable of
implementing a motor speed (rpm) of a cooling fan non-linearly
controlled at a duty ratio (%) of a PWM signal so as to improve
cooling efficiency.
[0004] 2. Description of the Related Art
[0005] Various electric and electronic devices such as information
processing devices such as a computer, OA devices, home appliances,
power supply devices, or the like, have used a cooling fan for
cooling heating generated due to operations of the devices.
[0006] Generally, revolutions, air volume, or the like, of a fan
motor driving the cooling fan are defined in consideration of an
expected use temperature of devices. Therefore, the devices need to
be designed to have the cooling fan in order to provide a constant
driving speed. In this case, cooling efficiency may be degraded or
noise may occur.
[0007] Further, a method for performing a control to change a speed
of the cooling fan according to a change in temperature has been
used.
[0008] As described above, a technology for the method for
controlling the driving speed of the cooling fan according to the
change in temperature is disclosed in KR Patent Application No.
10-2004-0045419. That is, the motor speed of the cooling fan is
controlled by a method of increasing the duty ratio % of the PWM
signal when an object to be cooled is at high temperature and thus,
the cooling fan needs to be operated at a high speed, and lowering
the duty ratio % of the PWM signal when an object to be cooled is
at a low temperature and thus, the cooling fan needs to be operated
at low temperature.
[0009] However, the control method linearly controls the motor
speed of the cooling fan according to the duty ratio (%) of the PWM
signal. In this case, the control method has the following
problems.
[0010] That is, when the object to be cooled is at a relatively
high-temperature and thus, the motor speed of the cooling fan needs
to be operated at a faster speed, the method for linearly
controlling the cooling fan according to the related art is
difficult to implement it.
[0011] To the contrary, when the object to be cooled is at a
relatively low temperature, there is a need to operate the motor
speed of the cooling fan at a slower speed so as to reduce power
consumption. Likewise, the method for linearly controlling the
cooling fan according to the related art is difficult to implement
it.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to provide a cooling
fan control device and a control method thereof capable of
controlling a motor speed (rpm) of the cooling fan non-linearly
controlled at a duty ratio (%) of a PWM signal.
[0013] According to an exemplary embodiment of the present
invention, there is provided a cooling. fan control device
including a temperature sensor, a microprocessor unit generating a
PWM signal corresponding to a temperature measured by the
temperature sensor, and a cooling fan driving unit driving the
cooling fan according to a duty ratio of the PWM signal, including:
a duty ratio detection unit receiving the PWM signal from the
microprocessor unit to detect the duty ratio (%) of the PWM signal;
and a duty ratio control device comparing the duty ratio (%)
detected from the duty ratio detection unit with a predetermined
threshold value, controlling the duty ratio (%) of the PWM signal
according to the comparison results, and then, outputting the
controlled PWM signal to the cooling fan driving unit.
[0014] The duty ratio control device may control the duty ratio (%)
of the PWM signal by comparing the duty ratio (%) detected from the
duty ratio detection unit with the predetermined threshold value
and adding and subtracting the predetermined duty ratio control
value to and from the detected duty ratio (%) of the PWM signal
according to the comparison results.
[0015] The duty control device may add the duty ratio control value
to the detected duty ratio (%) of the PWM signal when the duty
ratio (%) detected from the duty ratio detection unit is a
predetermined first threshold value or more; and subtract the duty
ratio control value from the detected duty ratio (%) of the PWM
signal when the duty ratio (%) detected from the duty ratio
detection unit is a predetermined second threshold value or less,
the first threshold value being larger than the second threshold
value.
[0016] The first threshold value may be any one of 70% to 90%, the
second threshold value may be any one of 10% to 30%, and the duty
ratio control value may be any one of 1% to 10%.
[0017] The cooling fan control device may further include a PWM
signal generation unit generating a new PWM signal by receiving the
PWM signal from the duty ratio control device and changing a
frequency of the PWM signal according to a predetermined frequency
value.
[0018] The PWM signal generation unit may perform a function of
setting the duty ratio (%) of the PWM signal to a lowest threshold
value when the duty ratio (%) of the PWM signal received from the
duty ratio control device is a predetermined lowest threshold value
or less.
[0019] According to an exemplary embodiment of the present
invention, there is provided a cooling fan speed control method,
including: (a) receiving a PWM signal generated corresponding to
temperature measured by a temperature sensor; (b) detecting a duty
ratio (%) of the PWM signal; (c) comparing the duty ratio (%)
detected at the detecting of the duty ratio with a predetermined
first threshold value; (d) when the duty ratio (%) detected at the
comparing of the duty ratio is below the predetermined first
threshold value, comparing it with the predetermined second
threshold value; and (e) generating a new PWM signal by changing
the frequency of the PWM signal according to the predetermined
frequency value when the duty ratio (%) exceeds the predetermined
second threshold value at the comparing of the duty ratio (%),
wherein the first threshold value is larger than the second
threshold value.
[0020] The cooling fan speed control method may further include at
the comparing of the duty ratio, when the detected duty ratio (%)
is the predetermined first threshold value or more, adding the
predetermined duty ratio control value to the detected duty ratio
(%) of the PWM signal; and generating a new PWM signal by changing
a frequency of the controlled PWM signal according to a
predetermined frequency value.
[0021] The cooling fan speed control method may further include: at
the comparing, when the detected duty ratio (%) is the
predetermined second threshold value or less, subtracting the
predetermined duty ratio control value from the detected duty ratio
(%) of the PWM signal; comparing the controlled duty ratio (%) of
the PWM signal with a lowest threshold value; and generating a new
PWM signal by changing the fixed frequency of the PWM signal
according to the predetermined frequency value when the controlled
duty ratio (%) of the PWM signal exceeds the lowest threshold
value.
[0022] The cooling fan speed control method may further include:
fixing the controlled duty ratio (%) of the PWM signal to a lowest
threshold value when the controlled duty ratio (%) of the PWM
signal is the lowest threshold value; and generating the new PWM
signal by changing the controlled frequency of the PWM signal
according to the predetermined frequency value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a block diagram of an entire power measurement
system according to an exemplary embodiment of the present
invention.
[0024] FIG. 2 is a diagram showing a waveform of a PWM signal.
[0025] FIG. 3A is a graph between a non-controlled duty ratio (%)
of the PWM signal and a motor speed (rpm) driving a cooling
fan.
[0026] FIG. 3B is a graph between a controlled duty ratio (%) of
the PWM signal and a motor speed (rpm) driving a cooling fan.
[0027] FIG. 3C is a graph coupling FIGS. 3A and 3B.
[0028] FIG. 4 is a flow chart of the method for controlling a
cooling fan according to the exemplary embodiment of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] Various advantages and features of the present invention and
methods accomplishing thereof will become apparent from the
following description of embodiments with reference to the
accompanying drawings. However, the present invention may be
modified in many different forms and it should not be limited to
the embodiments set forth herein. These embodiments may be provided
so that this disclosure will be thorough and complete, and will
fully convey the scope of the invention to those skilled in the
art. Like reference numerals throughout the description denote like
elements.
[0030] In addition, terms used in the present specification are for
explaining the embodiments rather than limiting the present
invention. Unless explicitly described to the contrary, a singular
form includes a plural form in the present specification. The word
"comprise" and variations such as "comprises" or "comprising," will
be understood to imply the inclusion of stated constituents, steps,
operations and/or elements but not the exclusion of any other
constituents, steps, operations and/or elements.
[0031] Hereinafter, a configuration and an acting effect of
exemplary embodiments of the present invention will be described in
more detail with reference to the accompanying drawings.
[0032] FIG. 1 shows a block diagram of an entire cooling fan
control device 100 according to an exemplary embodiment of the
present invention.
[0033] Referring to FIG. 1, according to the exemplary embodiment
of the present invention, a cooling fan control device 100
including a temperature sensor (not shown), a microprocessor unit
(not shown) generating a PWM signal corresponding to temperature
measured in the temperature sensor, and a cooling fan driving unit
(not shown) driving the cooling fan according to a duty ratio of
the PWM signal may include a duty ratio detection unit 110
receiving the PWM signal from the microprocessor unit to detect the
duty ratio (%) of the PWM signal; and a duty ratio control device
120 comparing the duty ratio (%) detected from the duty ratio
detection unit with a predetermined threshold value, controlling
the duty ratio (%) of the PWM signal according to the comparison
results, and then, outputting the controlled PWM signal to the
cooling fan driving unit.
[0034] Generally, a cooling fan control system first measures the
temperature of an object to be cooled by attaching the temperature
sensor to an object to be cooled. The temperature sensor may use
both an analog temperature sensor and a digital temperature sensor,
wherein as the analog temperature sensor, a thermister is generally
used. The thermister, which uses a characteristic in which
resistivity is changed in response to the change in temperature, is
connected to a dividing resistor in series. In this case, the
temperature voltage may be calculated by a resistance changing
value of the thermister and the dividing voltage of the dividing
resistor.
[0035] Next, the PWM signal corresponding the measured temperature
is generated in a microprocessor unit (MPU) (not shown) using the
signal output from the temperature sensor.
[0036] FIG. 2 is a diagram showing a waveform of the PWM signal
output from the microprocessor unit (MPU). The PWM signal may set a
high region to be on duty and may also set a low region to be on
duty. Herein, for convenience of explanation, the high region is
set to be on duty.
[0037] When the temperature of the object to be cooled is low and
thus, the low-speed rotation of the cooling fan is required, the
cooling fan may be rotated at a low speed by shortening the on duty
value (%) of the PWM signal shown in FIG. 2.
[0038] Meanwhile, when the temperature of the object to be cooled
is high and thus, the high-speed rotation of the cooling fan is
required, the cooling fan may be rotated at a high speed by
extending the period of the on duty value (%) of the PWM
signal.
[0039] As described above, the microprocessor unit (MPU) may
generate the PWM signal by controlling the ratio of on-off time in
a period corresponding to the temperature measured by the
temperature sensor, that is, the duty ratio (%).
[0040] The duty ratio detection unit 110 may serve a function of
receiving the PWM signal generated corresponding to the temperature
in the microprocessor unit (MPU) to detect the duty ratio (%) of
the received PWM signal.
[0041] The duty ratio (%) of the PWM signal may be detected using a
pulse edge detection circuit configured to include an integrator
including a resistor and a capacitor connected in parallel, a
delayer including a Schmitt trigger inverter circuit and an
inverter to receive and delay the pulse signal of the integrator, a
phase comparator including an exclusive-Or gate logic element to
compare the pulse signal of the delayer with the phase of the input
pulse signal, or the like. In addition, the duty ratio (%) of the
PWM signal may be detected by using several components generally
well known in the art to which the present invention pertains such
as a technology disclosed in KR Patent Laid-Open No. 1998-082412,
or the like.
[0042] The duty ratio control device 120 may perform a function of
receiving the data value relating to the duty ratio (%) of the PWM
signal detected from the duty ratio detection unit 110 to compare
the received data value with the predetermined threshold value to
control the duty ratio (%) of the PWM signal according to the
result value.
[0043] Describing in more detail, the duty ratio control device 120
compares the duty ratio (%) detected from the duty ratio detection
unit with the predetermined threshold value and adds and subtracts
the predetermined duty ratio control value to and from the duty
ratio (%) of the detected PWM signal according to the comparison
results to control the duty ratio (%) of the PWM signal.
[0044] Here, a duty ratio control value of the threshold value and
the duty ratio control device may be determined as the duty ratio
(%) value having a predetermined value.
[0045] Meanwhile, although not shown in the drawings, the duty
ratio control device 120 may include a memory, or the like, that
may store the threshold value, the comparison result value, or the
like.
[0046] Now, in the duty ratio control device 120, a method for
controlling the duty ratio (%) of the PWM signal detected by the
duty ratio detection unit 110 will be described in more detail.
[0047] When the duty ratio control device 120 receives the data
value relating to the duty ratio (%) of the PWM signal from the
duty ratio detection unit 110, the duty ratio control device 120
compares the received data value with a first threshold value and
when the duty ratio (%) of the PWM signal is the first threshold
value or more, the duty ratio control device 120 adds the duty
ratio control value to the detected duty ratio of the PWM
signal.
[0048] To the contrary, when the duty ratio (%) detected from the
duty ratio detection unit 110 is the predetermined second threshold
value or less, the duty ratio control value is subtracted from the
detected duty ratio (%) of the PWM signal.
[0049] In this case, the first threshold value may be set to be a
value larger than the second threshold value. Therefore, when the
duty ratio (%) of the PWM signal detected from the duty ratio
detection unit 110 is less than the first threshold value and the
second threshold value exceeds, the duty ratio control value is not
separately added and subtracted.
[0050] For example, if it is assumed that the first threshold
valued is 70%, the second threshold value is 30%, and the duty
ratio control value is 5%, when the duty ratio (%) of the PWM
signal detected from the duty ratio detection unit 110 is 30%, the
duty ratio control device 120 controls the duty ratio (%) of the
PWM signal to 25% and outputs the controlled duty ratio and when
the duty ratio (%) of the PWM signal detected from the duty ratio
detection unit 110 is 70%, the duty ratio control device 120 uses a
method of controlling and outputting the duty ratio (%) of the PWM
signal to 75%. Further, when the detected duty ratio (%) of the PWM
signal from the duty ratio detection unit 110 is above 30% to below
70%, the duty ratio detection unit 110 outputs the duty ratio of
the PWM signal as it is without performing a control.
[0051] The PWM signal passing through the duty ratio control device
120 may be transferred to a motor unit (not shown) driving the
cooling fan and drive the cooling fan according to the duty ratio
(%) of the PWM signal.
[0052] The driving speed of the cooling fan driven by the PWM
signal controlled by the duty ratio control device 120 will be
described below.
[0053] FIG. 3 shows a graph between the duty ratio (%) of the PWM
signal and the motor speed (rpm) driving the cooling fan, wherein
FIG. 3A shows a graph between the non-controlled duty ratio (%) of
the PWM signal and the motor speed (rpm) driving the cooling fan
and FIG. 3B shows the graph between the duty ratio (%) of the PWM
signal controlled by the duty ratio control device 120 and the
motor speed (rpm) driving the cooling fan.
[0054] As shown in FIG. 3A, when the separate control is not
performed, the motor speed (rpm) driving the cooling fan is
linearly proportional to the duty ratio (%) of the PWM signal. On
the other hand, when the duty ratio (%) of the PWM signal is
controlled by the duty ratio control device 120, as shown in FIG.
3B, the motor speed (rpm) corresponding to the duty ratio (%) to
which the duty ratio control value is added in a period (a) of duty
ratio (%) (1) or more corresponding to the first threshold value is
shown and the motor speed (rpm) corresponding to the duty ratio (%)
from which the duty ratio control value is subtracted in a period
(b) of duty ratio (%) (2) or less corresponding to the second
threshold value is shown. Meanwhile, since the duty ratio control
value is separately added and subtracted in a period (c) exceeding
the duty ratio (%) (2) corresponding to the second threshold value
and below the duty ratio (%) (1) corresponding to the first
threshold value, the motor speed (rpm) is shown similar to FIG.
3A.
[0055] According to the above-mentioned operation, the object to be
cooled may be more efficiently cooled. That is, FIG. 3C is a graph
coupling FIGS. 3A and 3B. As shown in FIG. 3C, when the object to
be cooled is at a relatively high temperature and thus, the duty
ratio (%) of the PWM signal enters period (a) of FIG. 3C, the
cooling fan control device 100 according to the embodiment of the
present invention may drive the motor speed (rpm) of the cooling
fan at a high speed by a difference of period (d), as compared with
the cooling fan control device according to the related art
linearly increasing.
[0056] To the contrary, when the object to be cooled is at a
relatively low temperature and thus, the duty ratio (%) of the PWM
signal enters period (b) of FIG. 3C, the cooling fan control device
100 according to the embodiment of the present invention may drive
the motor speed (rpm) of the cooling fan at a low speed by a
difference of period (e), as compared with the cooling fan control
device according to the related art linearly reduced, thereby
reducing the power consumption of the cooling fan control
device.
[0057] Herein, periods (d) and (e) may be increased or reduced by
controlling the duty ratio control value. That is, the motor speed
(rpm) may be controlled in periods (a) and (b).
[0058] Further, period (a) or (b) may be increased or reduced by
controlling the first threshold value and the second threshold
value.
[0059] Therefore, the duty ratio control value and the first
threshold value and the second threshold value may be appropriately
selected in consideration of the characteristics and the peripheral
environment of the object to be cooled.
[0060] Generally, the first threshold value may be set to be any
one in the range of 70% to 90%, the second threshold value may be
set to be any one in the range of 10% to 30%, and the duty ratio
control value may be set to be any one in the range of 1% to 10%.
However, this is a general numerical range for helping
understanding and therefore, it is to be noted that the exemplary
embodiment of the present invention is not necessarily limited to
the above-mentioned numerical range.
[0061] Meanwhile, the cooling fan control device 100 according to
the exemplary embodiments of the present invention receives the PWM
signal from the duty ratio control device 120 and may further
include a PWM signal generation unit 130 that changes the frequency
of the PWM signal according to the predetermined frequency value to
generate a new PWM signal.
[0062] The frequency of the PWM signal generated corresponding to
the temperature measured by the temperature sensor may be selected
in a wide range between, for example, 100 Hz tO 100 KHz according
to a microprocessor unit (MPU) and thus, the PWM signal generation
unit 130 changes the frequency of the PWM signal output from the
duty ratio control device 120 to the predetermined frequency value
(generally, 25 KHz) in consideration of an audible frequency 20 to
20000 Hz of human to generate the new PWM signal.
[0063] However, when the frequency of the PWM signal is too high,
the duty loss may be increased. Therefore, it is preferable to
appropriately select the frequency value to be changed.
[0064] In addition, the PWM signal generation unit 130 may serve to
fix the duty ratio (%) of the PWM signal to the lowest threshold
value when the duty ratio (%) of the PWM signal input from the duty
ratio control device 120 is the predetermined lowest threshold
value or less.
[0065] That is, if the object to be cooled is a product using
current, the driving of the cooling fan needs to be minimally
secured except for the special situations. Therefore, the PWM
signal generation unit 130 sets the lowest threshold value and when
the duty ratio (%) of the PWM signal input from the duty ratio
control device 120 is the predetermined lowest threshold value or
less, that is, the case of period (f) of FIG. 3B, the cooling fan
may be operated at a minimum mode by fixing the duty ratio of the
PWM signal to the lowest threshold value.
[0066] Therefore, the lowest threshold value may be set to be lower
than the second threshold value. As a result, the lowest threshold
value needs to be set in consideration of the duty ratio (%) in
which the duty ratio control value is subtracted from the duty
ratio control device 120.
[0067] A cooling fan control method according to the cooling fan
control device 100 of the present invention will be described
below.
[0068] FIG. 4 is a flow chart of the method for controlling a
cooling fan according to the exemplary embodiment of the present
invention. Referring to FIG. 4, the cooling fan control method
according to the exemplary embodiment of the present invention may
first perform receiving the PWM signal generated corresponding to
the temperature measured by the temperature sensor in the duty
ratio detection unit 110 (S10).
[0069] When the PWM signal is input, the duty ratio detection unit
110 may perform detecting the duty ratio (%) of the input PWM
signal (S20).
[0070] When the duty ratio (%) of the PWM signal is detected
according to step S20, the duty ratio detection unit 110 outputs
the data value relating to the detected duty ratio (%) to the duty
ratio control device 120 and the duty ratio control device 120 may
perform comparing the data value with the predetermined first
threshold value (S30).
[0071] When the detected duty ratio (%) is below the predetermined
first threshold value, the duty ratio control device 120 may
perform again comparing it with the predetermined second threshold
value (S40).
[0072] At step S40, when the detected duty ratio (%) exceeds the
predetermined second threshold value, the duty ratio control device
120 does not perform the separate control for the PWM signal
detected according step S20 and outputs it to the PWM signal
generation unit 130.
[0073] The PWM signal generation unit 130 performs generating the
new PWM signal by changing the frequency of the input PWM signal
according to the predetermined frequency value (S50) and may drive
the cooling fan by transferring the new PWM signal to the motor
unit (not shown) driving the cooling fan.
[0074] Meanwhile, at step S30, when the detected duty ratio (%) is
the predetermined first threshold value or more, the duty ratio
control device 120 performs adding the predetermined duty ratio
control value to the detected duty ratio (%) of the PWM signal
(S60) and outputs the controlled PWM signal to the PWM signal
generation unit 130.
[0075] Then, the PWM signal generation unit 130 generates the new
PWM signal of which the frequency is changed according the
predetermined frequency value through step S50 and may drive the
cooling fan by transferring the new PWM signal to the motor unit
(not shown) driving the cooling fan. Therefore, when the object to
be cooled is at a relatively high temperature, the object to be
cooled may be more efficiently cooled than the cooling speed
control method according to the related art.
[0076] Further, at step S40, when the detected duty ratio (%) is
the predetermined second threshold value or less, the duty ratio
control device 120 performs subtracting the predetermined duty
ratio control value from the detected duty ratio (%) of the PWM
signal (S70) and then, outputs the controlled PWM signal to the PWM
signal generation unit 130.
[0077] The PWM signal generation unit 130 performs comparing the
controlled duty ratio (%) of the PWM signal with the predetermined
lowest threshold value (S80) and when the controlled duty ratio (%)
of the PWM signal exceeds the lowest threshold value, is branched
into step S50 to drive the cooling fan. Therefore, when the
objected to be cooled is at the relatively low temperature, the
power consumption of the cooling fan control device can be reduced
as compared with the cooling fan control method according to the
related art.
[0078] In order to secure the lowest driving of the cooling fan,
when the controlled duty ratio (%) of the PWM signal is the lowest
threshold value at step S80, fixing the controlled duty ratio (%)
of the PWM signal to the lowest threshold value is performed (S90)
and is branched to step S50, thereby driving the cooling fan.
[0079] As set forth above, the cooling fan control device and the
control method thereof the exemplary embodiments of the present
invention can operate the motor speed (rpm) of the cooling fan at
faster speed than the cooling fan control device linearly increased
and the control method thereof according to the related art when
the object to be cooled is at the relatively high temperature,
thereby improving the cooling efficiency.
[0080] In addition, the exemplary embodiments of the present
invention can operate the motor speed of the cooling fan at a
slower speed than the cooling fan control device linearly increased
and the control method thereof according to the related art when
the object to be cooled is at the relatively low temperature,
thereby reducing the power consumption of the cooling fan control
device.
[0081] The present invention has been described in connection with
what is presently considered to be practical exemplary embodiments.
Although the exemplary embodiments of the present invention have
been described, the present invention may be also used in various
other combinations, modifications and environments. In other words,
the present invention may be changed or modified within the range
of concept of the invention disclosed in the specification, the
range equivalent to the disclosure and/or the range of the
technology or knowledge in the field to which the present invention
pertains. The exemplary embodiments described above have been
provided to explain the best state in carrying out the present
invention. Therefore, they may be carried out in other states known
to the field to which the present invention pertains in using other
inventions such as the present invention and also be modified in
various forms required in specific application fields and usages of
the invention. Therefore, it is to be understood that the invention
is not limited to the disclosed embodiments. It is to be understood
that other embodiments are also included within the spirit and
scope of the appended claims.
* * * * *