JP2001045784A - Control device of brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the control device of a brushless motor for enabling appropriate speed control by avoiding influence due to fluctuation of a DC power supply voltage. SOLUTION: A voltage detection correcting circuit 3 amplifies the potential difference between a voltage V1, obtained by dividing a power supply voltage signal ACC and a bias voltage V2 with an operational amplifier 3a and outputs a voltage deviation detecting signal V3, and an amplitude pulse width multiplying circuit 5 compares a sawtooth wave signal OSC from a sawtooth wave generating circuit 4 with the voltage deviation detection signal V3 for outputting, and at the same time, multiplies the output by a rotation instruction signal Vin. A smoothing circuit 6 smoothes a multiplied signal V4, and a control voltage adjustment circuit 7 amplifies the rotation instruction signal Vin which is attenuated by the amplitude pulse width multiplying circuit 5 and the smoothing circuit 6 sets a signal Vin2 to an appropriate level and supplies it to a drive control circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a brushless motor which can perform an appropriate speed control while avoiding the influence of a fluctuation of a DC power supply voltage.

[0002]

2. Description of the Related Art A brushless motor generally employs a system in which a DC power supply is turned on and off by a switching element to generate an AC current, and the AC current is supplied to an armature coil. On the other hand, an external rotation instruction signal for instructing the number of rotations is input to a microcomputer, and the microcomputer generates a gate signal by pulse width modulation of the rotation instruction signal, and the gate signal is generated by a field effect transistor or the like. Supply to the configured switching circuit. The switching circuit synchronizes the timing with the supplied gate signal to energize the armature coil provided on the stator.
Then, the rotor is rotated by the attractive / repulsive force of the magnetic force generated from the armature coil and the magnetic force of the field permanent magnet provided on the rotor.

[0003]

However, when a conventional brushless motor control device is used for controlling a blower motor or the like of an air conditioner powered by a battery of an automobile, for example, the ambient temperature of the battery or Since the battery voltage (power supply voltage) fluctuates depending on the state of current supply to other loads such as headlights, the energy applied to the armature coil fluctuates, which may hinder proper speed control. That is, when the power supply voltage decreases, the actual rotation speed decreases below a desired rotation speed, and conversely, when the power supply voltage increases, the actual rotation speed increases.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a brushless motor control device capable of performing appropriate speed control while avoiding the influence of fluctuations in the DC power supply voltage. To provide.

[0005]

According to a first aspect of the present invention, there is provided a control apparatus for a brushless motor, comprising: a control unit for controlling a fluctuation range of a DC power supply voltage of the brushless motor with respect to a predetermined reference voltage; A voltage fluctuation detection circuit for detecting, a pulse width modulation circuit for pulse width modulating the fluctuation width detection signal output from the voltage fluctuation detection circuit, a pulse width modulation signal from the pulse width modulation circuit and the brushless motor. A multiplication circuit that multiplies the DC rotation instruction signal for instructing the number of revolutions and corrects the DC rotation instruction signal based on the detected fluctuation width; and a corrected DC rotation output from the multiplication circuit. A gist of the present invention is to have a smoothing circuit for smoothing the instruction signal.

In the control device for a brushless motor according to the present invention, the fluctuation range of the DC power supply voltage of the brushless motor with respect to a predetermined reference voltage is detected by a voltage fluctuation detection circuit, and the detection signal is sent to a pulse width modulation circuit. The pulse width modulation is performed, and then the multiplication circuit multiplies the pulse width modulation signal by the DC rotation instruction signal indicating the rotation speed of the brushless motor, thereby correcting the DC rotation instruction signal based on the detected fluctuation width. Is performed, and in the smoothing circuit, the pulse-corrected DC rotation instruction signal after the correction is smoothed.

In a control device for a brushless motor according to a second aspect of the present invention, the voltage fluctuation detection circuit includes an operational amplifier configured inside an integrated circuit, and the operational amplifier is configured to control the predetermined reference voltage or the DC power supply voltage. Is input via an external voltage dividing circuit.

In the control device for a brushless motor according to a second aspect of the present invention, the voltage dividing circuit is constituted by a resistor, the resistance value of which is adjusted according to the characteristics of the brushless motor, and a correction reference point of the DC power supply voltage. That is, a voltage to which no correction is applied is set.

According to a third aspect of the present invention, in the control device for a brushless motor, the voltage fluctuation detecting circuit includes an operational amplifier configured inside the integrated circuit, and the operational amplifier has an external resistor for setting an amplification degree. It is characterized by having been done.

In the brushless motor according to the third aspect, an external resistor for setting the amplification degree is adjusted according to the characteristics of the brushless motor, and the correction amount of the DC rotation instruction signal is set.

[0011]

According to the control apparatus for a brushless motor according to the first aspect of the present invention, the DC rotation instruction signal is corrected in accordance with the fluctuation of the DC power supply voltage, so that the influence of the voltage fluctuation can be avoided and the appropriate Speed control becomes possible.

Further, according to the brushless motor control device of the present invention, it is possible to adjust the correction reference point of the DC power supply voltage without changing the integrated circuit every time.

Further, according to the control device for a brushless motor according to the third aspect of the present invention, the correction amount of the DC rotation instruction signal can be adjusted without changing the integrated circuit every time.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a control device for a brushless motor according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of a control device for a brushless motor according to the present invention. A brushless motor 100 is used as a blower motor for an air conditioner of an automobile. This brushless motor 10
Reference numeral 0 denotes a motor body 1, a switching circuit 2 for energizing an armature coil (not shown) provided in the motor body 1, a custom IC 50, a peripheral circuit of the custom IC 50, and the like. Signal V
This is to rotate the rotor (not shown) of the motor main body 1 at the rotation speed indicated by “in”. Here, the custom IC 50 is a circuit in which circuits shared by various motors are integrated and housed in a dedicated package. The dedicated package is provided with terminals T1 to T10 for connecting peripheral circuits.

The switching circuit 2 is composed of a field effect transistor, and supplies a current to the armature coil of the motor body 1 by a gate signal supplied from the drive control circuit 8 provided in the custom IC 50.

The custom IC 50 and its peripheral circuits shown in FIG. 1 constitute a voltage detection and correction circuit 3, a sawtooth wave generation circuit 4, an amplitude pulse width multiplication circuit 5, a smoothing circuit 6, a control voltage adjustment circuit 7, and a drive control circuit 8. Then, by using these circuits, the rotation instruction signal Vin is corrected so as to cancel the fluctuation of the power supply voltage, so that appropriate speed control of the brushless motor 100 is performed.

The voltage detection and correction circuit 3 is a circuit for detecting and amplifying a potential difference (variation width) of a power supply voltage signal ACC supplied to the brushless motor 100 with respect to a correction reference point. The voltage detection and correction circuit 3 includes an operational amplifier 3a inside the custom IC 50. The bias voltage V2 applied to the non-inverting input terminal of the custom IC 50 via the terminal T2 is obtained by converting the stabilized voltage VDD to the resistances R4 and R5. Is set with partial pressure. On the other hand, a voltage signal V1 supplied to the inverting input terminal via the resistor R3 and the terminal T1 is a power supply voltage signal AC supplied from a power supply circuit or a battery (not shown).
C is divided and set by the resistors R1 and R2. For example, when the bias voltage V2 is set to 3V and the correction reference point (voltage value without correction) is to be ACC = 12V, the resistance value of the resistor R2 is changed to the resistance value of the resistor R2 and the resistance value of the resistor R1. The partial pressure ratio divided by the sum of the values may be set to 0.25. Then, a feedback resistor R6 of the operational amplifier 3a is connected between the terminal T3 and the terminal T1 connected to the output of the operational amplifier 3a. In this voltage detection correction circuit 3,
A correction amount for the rotation instruction signal Vin is set by the resistors R3 and R6. The output of the operational amplifier 3a (referred to as a voltage deviation detection signal V3) is
Inside 0, it is supplied to the amplitude pulse width multiplication circuit 5.

The sawtooth wave generating circuit 4 outputs a sawtooth wave signal OSC having a frequency of 20 kHz to the amplitude pulse width multiplying circuit 5, and a pulse for the voltage deviation detection signal V3 together with the amplitude pulse width multiplying circuit 5. Performs width modulation.
An open collector type output comparator 4a is provided inside the custom IC 50, and its non-inverting input terminal is connected in series with a resistor R8, a resistor R9 and a resistor R10 from a DC 6V power supply, and grounds the resistor R10. The voltage at the connection point between the resistors R8 and R9 of the voltage divider circuit is input. On the other hand, the inverting input terminal includes a resistor R9 and a resistor R1.
A connection point voltage of 0 is input. The inverting input terminal is connected to the output of the comparator 4a. The output of the comparator 4a is further connected to a constant current source IS1 whose one end is connected to the terminal T4 and whose current value is set by a resistor R7 whose other end is grounded externally. Further, the output of the comparator 4a is connected via a terminal T5 to the positive electrode of a capacitor C2 whose negative electrode is grounded externally. The sawtooth signal OSC is generated by the charge / discharge operation of the above-described circuit. Note that the brushless motor 100 is 3000 rpm (5
(Corresponding to 0 rotation / sec) or less. By setting the frequency of the sawtooth signal OSC higher than this rotation speed, more responsive control becomes possible.

The amplitude pulse width multiplying circuit 5 is a circuit that performs pulse width modulation on the voltage deviation detection signal V3, and multiplies the pulse width of the pulse width modulation signal by the amplitude of the rotation instruction signal Vin. The amplitude pulse width multiplying circuit 5 includes an open collector type output comparator 5a, input resistors R11 and R12 connected to its inverting input terminal and non-inverting input terminal, respectively, and a resistor R13 having one end connected to the output of the comparator 5a. And The voltage deviation detection signal V3 from the voltage detection and correction circuit 3 is input to the non-inverting input terminal of the comparator 5a via the resistor R12. on the other hand,
The sawtooth signal OSC from the sawtooth generation circuit 4 is input to the inverting input terminal of the comparator 5a via the resistor R11. Then, the rotation instruction signal Vin input from the terminal T6 of the custom IC 50 is connected to the output of the comparator 5a via the resistor R13.
Is sent to the smoothing circuit 6 outside the custom IC 50 connected to the terminal T7.

The smoothing circuit 6 is a circuit for smoothing the corrected rotation instruction signal Vin multiplied by the amplitude pulse width multiplying circuit 5, and includes a resistor R14 having one end connected to the terminal T7.
And a capacitor C1 connected between the other end of the resistor R14 and the ground. And capacitor C
The first positive electrode gives the smoothed voltage V5 to the control voltage adjusting circuit 7.

The control voltage adjusting circuit 7 is an amplifier circuit for returning the rotation instruction signal Vin, which has passed through the amplitude pulse width multiplying circuit 5 and the smoothing circuit 6 and attenuated, to the original voltage range.
It comprises an operational amplifier 7a, resistors R16 and R17 for setting the amplification degree, and an input resistor R15.
The control voltage adjustment circuit 7 inputs the voltage V5 to the non-inverting input terminal of the operational amplifier 7a via the resistor R15 and the terminal T8. On the other hand, the inverting input terminal of the operational amplifier 7a is connected to one end of the resistor R16 via the terminal T9,
To the other end. Further, a feedback resistor R17 of the operational amplifier 7a is connected between the terminal T9 and the terminal T10. Then, the output Vin2 of the operational amplifier 7a is supplied to the drive control circuit 8.

The drive control circuit 8 generates a gate signal based on the corrected rotation instruction signal Vin2 given from the control voltage adjustment circuit 7, and supplies the gate signal to the field effect transistor of the switching circuit 2.

FIG. 2 is a sectional view of the brushless motor 100 in the direction of the rotation axis of the motor body 1. The brushless motor 100 is an outer rotor type brushless motor having a three-phase armature coil. The inner peripheral stator 1a shown in FIG. The armature coil 1b is arranged with the portion as a core. Outside the stator 1a, 90
Cylindrical rotors 1c having main magnets 1c1 to 1c4 (permanent field magnets) are arranged at intervals of degrees.
Further, the sensor magnet 1d shown in this figure is formed with two N poles and two S poles alternately magnetized at an equal angle, and is attached to a shaft 1e that rotates integrally with the rotor 1c. Magnetic sensors IC1 to IC3 for detecting the magnetic poles of the sensor magnet 1d are uniformly arranged on the inner periphery of the stator at an angle of 120 degrees.

The armature coil 1b configured as described above
, An alternating current is supplied from the switching circuit 2,
Due to the magnetic force generated from the armature coil 1b and the attraction / repulsion between the main magnets 1c1 to 1c4, the rotor 1c
Is driven to rotate.

Next, the operation of the first embodiment of the control device for a brushless motor according to the present invention will be described with reference to FIG.

As described above, the brushless motor 100 is used for a blower motor powered by an automobile battery. Therefore, the power supply voltage signal ACC varies depending on the ambient temperature of the battery and the current supply state of headlights and the like. It fluctuates as shown in FIG. In the present embodiment,
Instead of directly supplying the rotation instruction signal Vin to the drive control circuit 8, the following correction is performed to avoid the influence of the voltage fluctuation of the DC power supply.

The voltage detection and correction circuit 3 amplifies the potential difference between the voltage V1 and the bias voltage V2 by the operational amplifier 3a, and as a result, as shown in FIG.
Conversion is performed so as to be DD or less. Moreover, the operational amplifier 3a
Performs the inversion amplification, the higher the power supply voltage signal ACC, the lower the voltage deviation detection signal V3.

The sawtooth wave generating circuit 4 outputs a sawtooth signal OSC (20 kHz) as shown in FIG. Hereinafter, the generation process of the sawtooth signal OSC will be described.

In the sawtooth wave generating circuit 4 shown in FIG. 1, since the non-inverting input terminal voltage of the comparator 4a is applied with a positive voltage with respect to the inverting input terminal voltage, the output is in a high impedance state. Therefore, the capacitor C2 is charged from the constant current source IS1 and the sawtooth signal OS
The voltage of C gradually increases. Then, the comparator 4a
When the voltage of the non-inverting input terminal of
When a is inverted, the current from the constant current source IS1 and the discharge current from the capacitor C2 are absorbed by the output of the comparator 4a. Due to this inversion operation, a positive voltage is again applied to the non-inversion input terminal of the comparator 4a, so that the charging operation is restarted. Therefore, the charging and discharging operations described above
A sawtooth signal OSC as shown in (c) is obtained.

The frequency of the sawtooth signal OSC can be varied by varying the resistance value of the resistor R7 or the capacitance of the capacitor C2.
By setting the frequency to 0 kHz, good responsiveness is obtained. Further, the amplitude can be adjusted by adjusting the resistors R8 to R10.

Comparator 5 of amplitude pulse width multiplying circuit 5
a is a comparison between the sawtooth signal OSC and the voltage deviation detection signal V3, and a pulse signal V4 as shown in FIG.
(OPEN) is output. That is, a signal that is turned on in a period in which the sawtooth signal OSC is lower than the voltage deviation detection signal V3 is obtained. Here, for convenience of explanation, the waveform when the output terminal of the comparator 5a is opened is shown here. As described above, by using the sawtooth signal OSC having a higher frequency than the rotation speed of the brushless motor, an effect of improving the response of the correction can be obtained.

FIG. 4D illustrates a rotation instruction signal Vin superimposed on this waveform. This signal is input from an auto-amplifier of the air conditioner or the like.
It is necessary to adjust the number of rotations, and as shown in this figure, it is variable within a predetermined voltage range (in this embodiment, a range from 0 V to VDD).

The amplitude pulse width multiplying circuit 5 combines this rotation instruction signal Vin with the output signal of the comparator 5a via the resistor R13 and multiplies it, thereby obtaining V4 (OPEN) as shown in FIG. And outputs a signal V4 in which a portion exceeding the rotation instruction signal Vin in the waveform is cut. That is, a result obtained by multiplying the amplitude by the pulse width is obtained.

The smoothing circuit 6 smoothes the signal V4 shown in (e) and responds to a linear change in the rotation instruction signal Vin.
As shown in (f), a signal V5 that rises so as to compensate for the reduced portion of the power supply voltage signal ACC is obtained and supplied to the control voltage adjusting circuit 7.

As shown in FIG. 4A, 0 V is applied before passing.
The rotation instruction signal Vin, whose amplitude can be varied in the range of the voltage VDD from, is attenuated by passing through the amplitude pulse width multiplying circuit 5 and the smoothing circuit 6, and the amplitude variable width is reduced. The control voltage adjusting circuit 7 amplifies the attenuated signal (smoothed signal V5) with an amplification degree set by the resistance values of the resistors R16 and R17 as shown in FIG. Is generated and output to the drive control circuit 8.

As described above, in the present embodiment, the rotation instruction signal Vin is corrected so as to cancel the fluctuation of the power supply voltage signal ACC, so that the influence of the power supply voltage fluctuation can be avoided to achieve an appropriate speed. Control can be performed.

Moreover, since a peripheral circuit is connected to the outside of the custom IC 50 via an adjustment terminal, by changing the circuit constant of the peripheral circuit, correction according to the characteristics of the brushless motor can be performed without changing the custom IC itself. Is possible.

FIG. 5 is a diagram for explaining a method of adjusting the correction amount of the rotation instruction signal Vin described above.

As shown in FIG. 3A, the sawtooth wave generation circuit 3
Is input to the inverting input terminal of the amplitude pulse width multiplying circuit 5 and the voltage deviation detection signal V3 is input to the non-inverting input terminal, the open-time output V4 (OPEN) of the comparator 5a becomes The waveform shown in FIG. Here, the voltage deviation detection signal V3a when the amplification of the operational amplifier 3a is set to be high by adjusting the resistance values of the resistors R3 and R6 is shown in FIG. Since the voltage becomes relatively higher than the wave signal OSC, the comparator 5a
The pulse width at the time of open output (illustrated by t2 in FIG. 4D) is the pulse width before the amplification degree is increased (FIG. 4B).
Exemplarily at t1). That is, the correction amount can be largely adjusted by setting the amplification degree of the operational amplifier 3a high.

The voltage deviation detection signal V3 and the sawtooth signal OS
By adjusting the potential difference from C, the above correction amount can be adjusted. Conversely, the same effect can be obtained by adjusting the amplitude of the sawtooth signal OSC by changing the resistances R8 to R10. can get.

FIG. 6 is a diagram showing a method of setting a correction reference point.

As described above, when the bias voltage V2 is 3
When set to V, the power supply voltage correction reference point is set to AC
When it is desired to set C = 12 V, the resistance value of the resistor R2 is
The voltage division ratio divided by the sum of the resistance value of the resistor 2 and the resistance value of the resistor R1 may be set to 0.25. The correction reference point is ACC
= 13V, the partial pressure ratio may be set to 0.23. As described above, in the present embodiment, the custom IC
The correction reference point can be freely set by setting the resistance value without changing the value of the reference value 50 every time.

The correction reference point can also be set by adjusting the resistance value of the resistor R4 or the resistor R5 to vary the bias voltage V2.

As described above, in the control device of the brushless motor of this embodiment, even if the power supply voltage fluctuates, the voltage detection and correction circuit 3 detects the potential difference from the reference voltage, and the sawtooth wave generation circuit 4. The rotation instruction signal V is output by the amplitude pulse width multiplying circuit 5, the smoothing circuit 6, the control voltage adjusting circuit 7, and the like.
Since in is corrected, appropriate speed control can be performed while avoiding the influence of the fluctuation of the DC power supply voltage. In addition, since the control device is configured by hardware, correction, adjustment of the correction reference point and the correction amount can be performed without changing software. As a result, it is possible to reduce the development cost and the development period.

The control device for a brushless motor according to the present invention is not limited to use in a blower motor, but can be applied to various brushless motors such as a radiator motor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a control device for a brushless motor according to the present invention.

FIG. 2 is a diagram showing a configuration of a main body of the brushless motor 100 shown in FIG.

3 is a waveform diagram of each part of the brushless motor 100 shown in FIG.

FIG. 4 is a diagram illustrating an operation of the control voltage adjustment circuit 7 shown in FIG.

FIG. 5 is a diagram illustrating a method for adjusting a correction amount in the embodiment shown in FIG. 1;

FIG. 6 is a diagram illustrating a method of setting a correction reference point in the embodiment shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 motor body 2 switching circuit 3 voltage detection and correction circuit 4 sawtooth wave generation circuit 5 amplitude pulse width multiplication circuit 6 smoothing circuit 7 control voltage adjustment circuit 8 drive control circuit 50 custom IC 100 brushless motor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Eiji Takahashi Inventor F-term (reference) 5H560 AA01 BB04 BB12 DA01 DC13 EB01 JJ08 SS02 TT05 TT07 TT10 UA05 XA03 XA12 5-24-15 Minamidai, Nakano-ku, Tokyo

Claims (3)

[Claims] 1. A voltage fluctuation detecting circuit (3) for detecting a fluctuation width of a DC power supply voltage of a brushless motor (100) with respect to a predetermined reference voltage, and the fluctuation width outputted from the voltage fluctuation detection circuit (3). Pulse width modulation circuit (4,
5) multiplying the pulse width modulation signal from the pulse width modulation circuit (4, 5) by a DC rotation instruction signal indicating the number of rotations of the brushless motor (100); And a smoothing circuit (6) for smoothing the corrected DC rotation instruction signal output from the multiplying circuit (5). Control device. 2. The voltage fluctuation detection circuit (3) includes an operational amplifier (3a) configured inside an integrated circuit (50),
The operational amplifier (3a) converts the predetermined reference voltage or the DC power supply voltage to an external voltage dividing circuit (R1, R2, R
4. The control device for a brushless motor according to claim 1, wherein the input is performed via the input terminal (4, R5). 3. The voltage fluctuation detection circuit (3) includes an operational amplifier (3a) configured inside an integrated circuit (50),
The control device for a brushless motor according to claim 1 or 2, wherein resistors (R3, R6) for setting an amplification degree are externally attached to the operational amplifier (3a).