JPS6040276B2 - Motor drive control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor drive control device, and in particular to a pulse width modulation (PWM) method suitable for drive control of polyphase motors used in video tape recorders, turntables, etc. The present invention relates to a drive control device.

FIG. 1 shows the basic configuration of a drive control device for a three-phase motor. That is, the motor 2 and the frequency generator 4 are interlocked, and the frequency generator 4 generates an alternating current signal (frequency signal) having a frequency proportional to the rotation speed of the motor 2. This frequency signal is converted into pulses by a program counter 6 as a pulse conversion circuit, and is converted into pulses by a frequency-voltage conversion circuit 8.
has been entered. The frequency-voltage conversion circuit 8 is composed of a sawtooth wave generation circuit 10 and a sample hold circuit 12, and the pulse is given as a trigger signal to the chain tooth wave generation circuit 1, and at the same time, a sample pulse is sent to the sample hold circuit 12. given as.

The sawtooth wave generation circuit 10 sequentially generates a mirror-tooth wave having a peak value proportional to the synchronization in synchronization with the pulse, while the sample hold circuit 12 generates a mirror-tooth wave generated by the sawtooth wave generation circuit 10. It sequentially updates and holds the peak value of , and outputs the holding voltage. Since the peak value of the sawtooth wave is proportional to the period, this voltage output is a frequency-voltage conversion output. The sawtooth wave output of the sawtooth wave generation circuit 10 and the voltage output of the sample hold circuit 12 are given to a drive angle control signal generation circuit 14. This drive angle control signal generation circuit 14 generates a drive angle control signal having a different phase for each predetermined angle obtained by combining these signals, and this drive angle control signal is transmitted to the drive unit 16 provided for each phase. After being amplified by circuits 16A, 16B, 16C, each coil 2A, 2B, 2 of motor 2
C is individually given as a drive angle control input.

Further, the output of the sample and hold circuit 12 is given to each drive circuit 16A, 16B, and 16C as a drive control input, and the drive angle control input given to each coil 2A, 2B, and 2C is the output voltage of the sample and hold circuit 12. It is meant to be controlled.

In the case of the drive control device configured in this way, the driving force of the motor 2 is given as a linear operation, so if stepwise speed control is required, for example, the drive voltage drop with respect to the power supply voltage of the drive unit 16 is The amount corresponding to the integral of the drive current is lost as reactive power.

That is, the voltage difference between the voltage Vm applied to the motor 2 given by the frequency-voltage conversion output and the power supply voltage Vcc (Vcc-Vm)
and the product of the drive current m of motor 2 (Vcc - Vm) lm
becomes a power loss, and the driving force of the motor 2 is given by Vm·lm. From this relationship, in order to improve efficiency, Vm
It is possible to bring the voltage close to Vcc, but there is a limit due to the control range, and it is difficult to maintain high efficiency. Further, such loss is related to the heat dissipation design of the drive section 16 and the expansion of the allowable heat loss capacity, and is a cause of increasing the capacity and size of the agitation section 16. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a motor drive control device in which the power loss is reduced and the drive unit has a smaller capacity and size.

That is, the present invention includes a pulse conversion circuit that converts a signal obtained by rotation of a motor into a pulse, and a sawtooth wave generation circuit that generates a sawtooth wave voltage in synchronization with the pulse outputted from the pulse conversion circuit. , a sample hold circuit that holds the sawtooth skin voltage outputted by this sawtooth wave generating circuit in synchronization with the pulse, and a holding voltage outputted by this sample hold circuit at a fixed ratio. a drive angle control signal generation circuit that generates a plurality of drive angle control signals having a specific phase by combining the voltage divided by the voltage divided by the voltage and the lock-tooth wave voltage, and a reference having a higher frequency than the saw-tooth wave voltage. A reference oscillation circuit that generates a voltage waveform; and a pulse width modulation that is obtained by comparing the reference voltage waveform outputted by the reference oscillation circuit with the holding voltage outputted by the sample-hold circuit to generate a pulse width corresponding to the holding voltage. The present invention is characterized in that it is comprised of a comparator that converts the drive angle control signals into switching pulses, and a waveform conversion circuit that converts each drive angle control signal into an intermittent signal using the switching pulses output from the comparator. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the motor drive control device of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 2, the held output of the sample hold circuit 12 and its generation point are the drive angle control signal generation circuit 1.
The voltage is divided by four voltage dividing circuits 20 according to the phase setting.

In this case, the period of one mirror-tooth wave voltage input is set to 3600, and for example, in the case of three phases, the voltage from the generation point to the peak value is divided into three equal parts, so that the phase transition every 1200 is It is formed. This voltage output is given to the phase shift circuit 22 together with the sawtooth wave output generated by the mirror tooth wave generation circuit 10, and a phase shift signal having a phase shift of every 120 degrees is generated based on the comparison between the sample hold output and the divided voltage output. and is input to the drive angle control signal forming circuit 24.
The drive angle control signal forming circuit 24 forms a drive angle control signal having a phase shift of, for example, 12 steps based on the phase shift signal input. This driving angle control signal is given as a rectangular wave pulse having a constant phase shift and a pulse width necessary to obtain a predetermined driving force. This drive angle control signal is subjected to control processing in the drive control unit 26, and is then processed by the drive unit 1.
6 drive circuits 16A, 16B, and 16C.
The drive control section 26 is provided with a reference oscillation circuit 28 that generates a reference frequency signal, and the reference oscillation circuit 28',
A reference voltage waveform consisting of a voltage waveform such as a mirror tooth wave, a triangular wave, or an exponential wave having a higher frequency than the output of 10 is generated. This reference voltage waveform output is given to the comparator 30 together with the sample and hold output, and the sample and hold output is subjected to pulse width modulation using the reference voltage waveform, and is converted into a switching pulse having a pulse width corresponding to the voltage value. converted. This pulse is processed by AND circuits 32A and 32B as waveform conversion circuits provided for each phase.
, 32C together with the drive angle control signal, and the drive angle control signal, which is converted into an intermittent signal by the AND of both signals, is input to the drive unit 16. In this case, motor 2
A power supply voltage ycc is applied directly or through the coils 2A, 2B, and 2C. The operation of the above configuration will be explained with reference to the operation waveforms shown in FIGS. 3 and 4. In FIG. 3, A shows the output waveform of the frequency generator 4, B shows the converted output obtained by the program counter 6, and C shows the output waveform of the sawtooth wave generating circuit 10.

In C, Vph, , Vph2 and Vph3 are the holding outputs of the sample and hold circuit 12, VL is the generation point, and
V, , V2 indicate divided voltage levels in the voltage dividing circuit 201.

D and E indicate phase shift signals formed by the phase shift circuit 22 based on the voltage division output, the front green part of each pulse of D and E has a phase shift of 120o, and the rear part of each pulse has a phase shift of 3
It is 60o.

F, C and day are D in the drive angle control signal forming circuit 24.
The drive angle control signal obtained by combining the phase shift signals of

In FIG. 4, 1 indicates the output waveform of the reference oscillation 28,
Vph,', Vph2' and Vph3' are shown in Figure 3C above.
This is an enlarged display of Vph, , Vph2 and Vph3, and each waveform change corresponds to the above change.

1, Vph,′, Vph2′, and Vph3′
Each level has a relationship of Vph3'>Vph2'>Vph,', and as is clear from the level comparison of the reference oscillation frequency output, the driving of each section T, , T2, T3 of Vph,', Vph2', Vph3' The power is 1'4 depending on each level,
1'2, 1/1.

J indicates the switching pulse obtained by pulse width modulation in comparator 30'.

That is, each pulse shown in J has a pulse width corresponding to each driving force, and this makes it possible to set the speed. F'
, 〇 and H' are the waveforms shown by enlarging the time axis of the waveforms shown in Figure 3 F, C and 3, and K, L and M are the waveforms shown in J and F', G' and H'. The drive angle control signal waveform is converted into an intermittent signal by logical product with the waveform shown in FIG.

In this way, the drive unit 16 of the motor 2 is provided with a drive angle control signal obtained by converting an intermittent signal by pulse width modulation and waveform conversion.

Here, if the saturation voltage of the driving transistors in the driving circuits 16A, 16B and 16C is Vsat, the pulse period of the pulse width modulation (PWM) pulse is Ts, and the driving angle control signal time is Tc, then the driving circuits 16A, 16B, and 16C, 16C
The driving force of the motor 2 given by (Vcc-Vs
at)・lm・Tc/Ts, and the power loss is the saturation loss of the driving transistor lm・Vsat・Tc/Ts
Therefore, highly efficient driving force can be realized. As a result, in addition to reducing the capacity and size of the drive section 16, when a battery is used as a drive power source, the driving time can be extended, and when the circuit is integrated into an IC, the package power can be reduced.

In addition, although the case of a three-phase motor was explained in the embodiment, the present invention can also be applied to a polyphase motor with three or more phases.Moreover, although the drive angle control signal is set to have a phase shift of 1200 for the sake of explanation, In the case of phase, it goes without saying that even a configuration using signals having six phase shifts can be applied to the same aircraft.

As described above, according to the present invention, it is possible to reduce the power loss in the drive section, improve the drive efficiency of the motor, and make it possible to reduce the capacity and size of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the basic configuration of a general drive control device for a three-phase motor, FIG. 2 is a block diagram showing an embodiment of the motor drive control device of the present invention, and FIG. and FIG. 4 are explanatory diagrams showing the operating waveforms thereof.

2...Mode, 8...Frequency-voltage conversion circuit, 10...Chain tooth wave generation circuit, 12...
...Sample hold circuit, 14...Drive angle control signal generation circuit, 20...Voltage division circuit, 22
... Phase shift circuit, 24 ... Drive angle control signal forming circuit, 28 ... Reference oscillation circuit, 30 ...
...Comparator, 32A, 32B, 32C...AND circuit as a waveform conversion circuit.

Figure 1 Figure 4 Figure 2 Figure 3

Claims (1)

[Claims] 1. A pulse conversion circuit that converts a signal obtained by rotation of a motor into a pulse, a sawtooth wave generation circuit that generates a sawtooth voltage in synchronization with the pulse outputted by this pulse conversion circuit, and this sawtooth wave generation circuit. a sample and hold circuit that holds the sawtooth wave voltage outputted by the wave generation circuit in synchronization with the pulse outputted from the pulse conversion circuit; and a sample and hold circuit that divides the holding voltage outputted by this sample and hold circuit at a fixed ratio. a drive angle control signal generation circuit that generates a plurality of drive angle control signals having specific phases by combining the obtained voltage and the sawtooth wave voltage; and a reference voltage waveform having a higher frequency than the sawtooth wave voltage. and a reference oscillation circuit that generates a pulse according to the holding voltage by pulse width modulation obtained by comparing the reference voltage waveform outputted by this reference oscillation circuit and the holding voltage outputted by the sample hold circuit. a comparator for converting into a switching pulse having a width;
A motor drive control device comprising: a waveform conversion circuit that converts each drive angle control signal into an intermittent signal using a switching pulse output from the comparator.