JP3969246B2 - Driving device for cooling fan motor for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving device for a vehicle cooling fan motor that independently drives a plurality of cooling fan motors.
[0002]
[Problems to be solved by the invention]
A vehicle (for example, an automobile) is provided with a cooling fan for cooling a condenser of an engine radiator and an air conditioner (hereinafter referred to as an air conditioner), and the cooling fan is rotationally driven by a motor (for example, a DC motor). It is like that.
[0003]
As described above, when cooling at least one heat exchanger arranged in one room (the front part of the vehicle) using two cooling fans, it is efficient if the cooling is performed in a state where the respective airflows are uniform. Good things are generally known. Therefore, it is preferable to select two motors with ratings of, for example, 100 W + 100 W and 200 W + 200 W, and drive them with the same output.
[0004]
However, assuming a case of application to an actual automobile or the like, the upper limit of the output (power consumption) allocated to the cooling device is not always a good number. In addition, the motor rating is not set in a fine unit, and is set with a width of about several tens of watts. As a result, when the output upper limit is limited to 260 W, for example, the ratings of the two motors cannot be set to 130 W + 130 W, and there is a situation in which an unbalanced setting such as 100 W + 160 W, for example, is unavoidable.
[0005]
Therefore, in the conventional driving device, there are many cases where the two cooling fans are driven with the unbalanced setting, and there is a problem that the cooling cannot be performed efficiently.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle cooling fan motor that can be driven to improve cooling efficiency as much as possible even when the rated settings of the plurality of cooling fan motors are unbalanced. It is to provide a driving device.
[0007]
[Means for Solving the Problems]
According to the vehicle cooling fan motor drive device of the first aspect, even when the ratings of the plurality of cooling fan motors driven by the common drive power source and the common drive command signal given from the outside are different , the voltage correction is performed. Since the circuit changes the driving voltage equivalently in accordance with the difference in rating, the amount of air generated by each cooling fan can be made substantially uniform. Accordingly, it is possible to improve the cooling efficiency.
[0008]
According to the vehicle cooling fan motor drive device of claim 2, the voltage correction circuit outputs, in the amplifying unit, an amplified version of the difference between the power supply voltage and the voltage applied to the power supply side terminal of the switching element. Then, a voltage generated in accordance with the difference between the voltage and an externally supplied fan motor drive command signal is output as a modulation command signal to the pulse width modulation signal generation circuit. In other words, by appropriately setting the amplification factor in the amplification unit, the average value of the voltage applied by the pulse width modulation signal to both ends of the cooling fan motor winding can be changed according to the respective ratings. The drive voltage of the fan motor can be changed equivalently.
[0009]
According to the vehicle cooling fan motor drive device according to claim 3, when the number of cooling fan motors is two, the control circuit outputs to each of the two switching elements in response to the input of the drive command signal. About two pulse width modulation signals, it outputs in the state which made the fall start timing of at least one signal correspond with the rise end timing of the other signal.
[0010]
That is, when the phase relationship between the two pulse width modulation signals is as described above, for example, when the switching element on one signal side starts to turn off, the turn-on of the switching element on the other signal side is completely completed. It will be. Accordingly, the two switching elements are not switched simultaneously, and the generation of noise can be suppressed.
[0011]
According to the vehicle cooling fan motor drive device of the fourth aspect, the waveform shaping circuit shapes the signal waveform of the pulse width modulation signal into a trapezoidal waveform. In other words, when the carrier frequency is high, the output of the pulse width modulation signal alone may cause noise, but if the signal waveform is shaped into a trapezoidal shape, the rise and fall of the signal will become gradual, and the noise Can be suppressed.
[0012]
Further, by forming the signal waveform into a trapezoidal waveform, the turn-on time and turn-off time of the switching element tend to be longer. By applying the invention of claim 1, the overlap of the transient switching period is avoided. It becomes possible to do. Therefore, the noise reduction effect can be improved as a whole.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing the electrical configuration, a series circuit of a motor (cooling fan motor) 2A, a power MOSFET (switching element) 3A, a motor 2B and a power MOSFET 3B is connected in parallel between a battery (power source) 1 and the ground. ing. The drains of the FETs 3A and 3B are connected to the battery 1 through forward diodes 4A and 4B and a π-type filter 5.
[0014]
The rating of the motor 2A is 160W, and the rating of the motor 2B is 100W. The motor 2A rotates the cooling fan 51 and blows air to the radiator (heat exchanger) 52 and the condenser 54, and cools. The motor 2B rotates the cooling fan 53 and blows air to the radiator 52 and the condenser 54. And cooling is performed.
[0015]
The π-type filter 5 includes capacitors 6 and 7 and a coil 8. In addition, a noise removing capacitor 9 is connected in parallel to both ends of the diode 4.
[0016]
An engine ECU (Electronic Control Unit) 10 controls the engine of a vehicle and is configured with a microcomputer as a center. The drive control signal output from the engine ECU 10 is given to the input signal processing unit 12 of the control circuit unit 11. The engine ECU 10 outputs the drive control signal as a low-speed PWM signal having a carrier frequency of about 100 Hz, for example.
[0017]
The input signal processing circuit 12 temporarily F / V-converts the relatively low-speed PWM (pulse width modulation) signal and outputs it to the power supply voltage correction circuits 13A and 13B. The power supply voltage correction circuits 13A and 13B are supplied with the terminal voltage + B of the battery 1 and the drain voltages VDA and VDB of the FETs 3A and 3B. The power supply voltage correction circuits 13A and 13B generate PWM command signals based on these voltage signals and output them to the PWM signal generation circuit (pulse width modulation signal generation circuit, control circuit) 14.
[0018]
FIG. 2 mainly shows the detailed configuration of the power supply voltage correction circuits 13A and 13B and the PWM signal generation circuit 14. In the following description, the symbols A and B are not attached unless it is necessary to distinguish between them. The power supply voltage correction circuit 13 includes a voltage detection unit 15, an amplification unit 16, and a command signal output unit (modulation command signal output unit) 17.
[0019]
The voltage detection unit 15 includes voltage dividing resistors 18 and 19 connected in series between the battery 1 and the ground, and a common connection point thereof is a non-inverting input terminal of the operational amplifier 20 that configures the amplification unit 16. It is connected to the. A parallel circuit of a resistor 21 and a capacitor 22 is connected between the inverting input terminal and the output terminal of the operational amplifier 20, and the inverting input terminal is connected to the drain (power supply side terminal) of the FET 3 via the resistor 23. It is connected.
[0020]
The command signal output unit 17 is configured as an integration circuit including an operational amplifier 24, a resistor 25, and a capacitor 26, and an output terminal of the operational amplifier 20 constituting the amplification unit 16 is connected to an inverting input terminal of the operational amplifier 24 through the resistor 25. It is connected. The non-inverting input terminal of the operational amplifier 24 is supplied with an F / V converted command signal output from the input signal processing circuit 12.
[0021]
If the resistance values of the voltage dividing resistors 18A and 19A constituting the voltage detector 15A are R1 and R2, respectively, the resistors 21A and 23A constituting the amplifier 16A are assumed to be R2 and R1, respectively. Further, assuming that the resistance values of the voltage dividing resistors 18B and 19B constituting the voltage detection unit 15B are R3 and R4, respectively, the resistance values of the resistors 21B and 23B constituting the amplification unit 16B are R4 and R3, respectively.
[0022]
The PWM signal generation circuit 14 includes a carrier wave signal output unit 27, a phase shift unit 28, and a PWM signal generation unit 29. The carrier wave signal output unit 27 generates a carrier wave signal (for example, sawtooth wave, frequency 19 kHz) for performing PWM control and outputs it to two systems. The phase shift unit 28 is a circuit that shifts the phase of one system signal, and the PWM signal generation unit 29 (A, B) composed of two comparators includes a carrier signal having two different phases, The PWM signal is generated by comparing the level with the PWM command signal supplied from the command signal output unit 17 of the power supply voltage correction circuit 13. The PWM signal is output to the gates of the FETs 3A and 3B via the drive circuits 30A and 30B and the resistors 31A and 31B (waveform shaping circuit).
[0023]
Next, the operation of this embodiment will be described with reference to FIGS. The voltage signal VOA output from the amplifying unit 16A of the power supply voltage correction circuit 13A is expressed by equation (1). The drain voltage VDA is an average value.
VOA = B'A + (R2 / R1) (B'A-VDA) = (R2 / R1). (B-VDA)
... (1)
However, B′A is the detection voltage (R2 · B / (R1 + R2)) of the battery 1 divided by the voltage dividing resistors 18A and 19A. The capacitor 26 of the command signal output unit 17A is charged with a current corresponding to the difference between the voltage signal VOA and the command signal voltage output from the input signal processing circuit 12.
[0024]
Therefore, the PWM command signal output to the PWM signal generation unit 29 of the PWM signal generation circuit 14 is the difference between the drive voltage B applied to the motor 2A and the average value of the drain voltage VDA of the FET 3A (ie, the winding of the motor 2A). It is set according to the difference between the voltage obtained by amplifying the voltage (corresponding to the voltage applied to both ends of the line) and the command signal output by the engine ECU 10.
[0025]
Further, the voltage signal VOA output from the amplifying unit 16B of the power supply voltage correction circuit 13B is expressed by the equation (2). The drain voltage VDB is an average value.
VOB = B'B + (R4 / R3) (B'B-VDB) = (R4 / R3). (B-VDB)
... (2)
However, B′B is the detection voltage (R4 · B / (R3 + R4)) of the battery 1 divided by the voltage dividing resistors 18B and 19B. Therefore, even if the driving power source is the common battery 1 and the PWM duty command signal output from the engine ECU 10 is common, the voltage resistance values R1 to R4 are set as appropriate so that the power source voltage correction circuits 13A and 13B Since the PWM duty for switching the FETs 3A and 3B can be set differently due to the action, the drive voltages of the motors 2A and 2B having different ratings can be equivalently changed.
[0026]
FIG. 3 shows the applied voltage required to rotate the cooling fan by motors with ratings of 160 W and 100 W, respectively, to obtain the same air flow rate. For example, when the blast volume is 2000 m ³ / h, a 160 W motor may be driven at about 5.8 V, and a 100 W motor may be driven at about 7.0 V.
[0027]
When the FET 3 is turned on, a current flows from the battery 1 through the path of the motor 2, the FET 3, and the ground, and the motor 2 is energized. When the FET 3 is turned off, a delay current is regenerated to the battery 1 side via the diode 4 and the π-type filter 5. The regenerative current is smoothed by the capacitor 6 of the π-type filter 5.
[0028]
In this case, the gate signal output from the PWM signal generation circuit 14 to the FETs 3A and 3B is formed in a trapezoidal shape by the resistors 31A and 31B inserted in series with the signal lines, and one of them is phase-shifted by the phase shift unit 28. Thus, the phase relationship shown in FIG. 4 is obtained. That is, the falling start timing of the signal (B) and the rising end timing of the signal (A) are in agreement.
[0029]
When the phase relationship between the two signals is as described above, when the FET 3B starts turning off, the turning on of the FET 3A is completely completed. Therefore, the two FETs 3A and 3B are not simultaneously switched, and the generation of noise can be suppressed.
[0030]
In the waveform shown in FIG. 4, basically, the FETs 3A and 3B are alternately turned on, so that the amplitude of the power supply current ripple is suppressed and the waveform distortion is also suppressed, and the periods during which the FETs 3A and 3B are simultaneously turned off are both. The occurrence of a double component of the ripple frequency is suppressed because it does not occur every time the on / off is switched. Further, after satisfying these conditions, the signals (A) and (B) have a phase relationship that ensures a long period of time when one of the FETs 3A and 3B is on and the other is off as long as possible. It has become. This has the effect of reducing the regenerative current flowing through the capacitor 6 of the π-type filter 5.
[0031]
As described above, according to this embodiment, the motors 2A and 2B that rotate the two cooling fans 51 and 53 have different ratings, the drive power supply is the common battery 1, and the PWM duty command signal output from the engine ECU 10 is Even if they are common, the voltage correction circuits 13A and 13B can change the drive voltage equivalently according to the difference in their ratings, so that the amount of air generated by the cooling fans 51 and 53 can be made substantially uniform. . Accordingly, it is possible to improve the cooling efficiency.
[0032]
The amplifying unit 16 of the voltage correction circuit 13 outputs an amplified version of the difference between the voltage B ′ detected by the voltage detecting unit 15 and the voltage VD applied to the drain of the FET 3, and outputs the output voltage VOA and the engine. A voltage corresponding to the difference from the drive command signal supplied from the ECU 10 is output to the PWM signal generation circuit 14 as a PWM command signal. Therefore, by appropriately setting the amplification factor in the amplification unit 16, the average value of the voltage applied by the PWM signal to both ends of the windings of the motors 2A and 2B is changed according to the respective ratings, and the motors 2A and 2B. Can be equivalently changed.
[0033]
Also, the PWM signal generation circuit 14 has at least a falling start timing of one signal and a rising end timing of the other signal for two PWM signals respectively output to the two FETs 3A and 3B in response to the input of the drive command signal. Are output in a matched state, so that ripples in the power supply current and waveform distortion can be suppressed, the size of the capacitor 6 constituting the π-type filter 5 can be reduced, and noise generation can be suppressed. be able to.
[0034]
Since the resistor 31 as the waveform shaping circuit shapes the signal waveform of the PWM signal into a trapezoidal waveform, the rise and fall of the signal become gradual and the generation of noise can be suppressed. In this case, the turn-on time and turn-off time of the FET 3 tend to be longer. However, the operation of the PWM signal generation circuit 14 makes it possible to avoid an overlap of transient switching periods. The effect can be improved.
[0035]
The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or expansions are possible.
For example, by changing the resistance ratio between the power supply side and the ground side using the drive circuit as a push-pull output, a waveform in which the rise time and the fall time of the trapezoidal wave of the PWM signal are different may be output. .
The processing of the phase shift unit 28 in the PWM signal processing circuit 14 may be performed as necessary.
Further, the PWM signal is not limited to a trapezoidal wave, and may be a waveform having a substantially rectangular wave as shown in FIG. 5 depending on the relationship with an allowable noise level.
The configuration of the voltage correction circuit is not limited to that shown in FIG. 2, and any configuration may be used as long as the cooling fan motor drive voltage is equivalently changed to make the air flow rate of each cooling fan substantially uniform.
The switching element is not limited to the power MOSFET, but may be a power transistor, an IGBT, or the like. Further, it may be connected as a high-side switch.
There may be three or more cooling fan motors. In that case, it is not always necessary that all the ratings are different, and the present invention can be applied when the ratings are different for at least some of them.
[Brief description of the drawings]
FIG. 1 is a diagram showing an electrical configuration of a driving device for a vehicle cooling fan motor according to an embodiment of the present invention. FIG. 2 is a diagram mainly showing detailed configurations of a power supply voltage correction circuit and a PWM signal generation circuit. FIG. 3 is a diagram showing an applied voltage necessary to obtain the same air flow rate by rotating a cooling fan by motors with ratings of 160 W and 100 W, respectively. FIG. 4 is a diagram showing a phase relationship between two PWM signals. ] Equivalent to FIG. 4 showing a modified example
1 is a battery (power source), 2A and 2B are motors (cooling fan motors), 3A and 3B are power MOSFETs (switching elements), 5 is a π-type filter, 6 and 7 are capacitors, 8 is a coil, and 13A and 13B are power sources Voltage correction circuit, 14 is a PWM signal generation circuit (pulse width modulation signal generation circuit, control circuit), 15 is a voltage detection unit, 16 is an amplification unit, 17 is a command signal output unit (modulation command output unit), and 51 and 53 are Indicates a cooling fan.

Claims (4)

In a vehicle cooling fan motor drive device for independently driving a plurality of cooling fan motors having different ratings at least partially based on a common drive power supply and a common drive command signal given from the outside,
As with the air blowing amount uniformly generated by a plurality of cooling fans, characterized that you comprising a voltage correction circuit for equivalently changed in accordance with the driving voltage of each of the cooling fan motor to the difference between the rating of the motors Drive device for cooling fan motor for vehicle. A plurality of switching elements that are connected in series to the plurality of cooling fan motors and energize the cooling fan motor by being turned on,
A plurality of pulse width modulation signal generation circuits for generating and outputting pulse width modulation signals for switching the plurality of switching elements, respectively;
The voltage correction circuit includes:
An amplifier that outputs an amplified difference between a power supply voltage and a voltage applied to the power supply side terminal of the switching element;
The voltage generated in accordance with the difference between the drive command signal of the fan motor given from the voltage and the external output from the amplifier unit, modulation command output unit that outputs to the pulse width modulation signal generating circuit as a modulation command signal The driving device for a cooling fan motor for a vehicle according to claim 1, comprising: The number of cooling fan motors is two,
Two switching elements that are connected in series to the two cooling fan motors and energize the cooling fan motor by being turned on,
A π-type filter composed of a coil and a capacitor, arranged in a path of a regenerative current flowing to the power supply side when these two switching elements are turned off;
The two pulse width modulation signals respectively output to the two switching elements in response to an input of said drive command signal, while being matched and fall start timing of at least one signal, and a rising end timing of the other signals 3. A driving device for a cooling fan motor for a vehicle according to claim 1, further comprising:   4. The driving device for a cooling fan motor for a vehicle according to claim 3, further comprising a waveform shaping circuit for shaping the signal waveform of the pulse width modulation signal into a trapezoidal waveform.

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