JPH061992B2 - Motor drive controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a brushless servomotor, and more particularly, a PWM for controlling power supply to the motor.
The present invention relates to the improvement of the generation timing of control signals.

INDUSTRIAL APPLICABILITY The motor drive control device of the present invention is useful for drive control when precise control is desired in NC machine tools and the like.

[Prior Art] Conventionally, PWM (puluse width moduratio) has been used as a drive control method for a brushless servomotor that drives a machine tool or the like.
n) drive control is being performed.

This synchronizes the power supply based on the rotational position information of the brushless servo motor, and also applies pulse width modulation to the voltage applied to the brushless servo motor to bring the supply current closer to a sine wave, thereby rotating the magnetic field of the brushless servo motor. It reduces the pulsation and makes the drive smooth.

However, in the conventional PWM drive control method, the sampling timing of the rotational position information, which is the basic parameter of pulse width modulation, and the output timing of the PWM control signal are different, and the current supplied to the brushless servo motor is not shifted. Occurred and caused a torque ripple.

[Problems to be Solved by the Invention] The present invention has been devised in view of the above circumstances,
To provide a motor drive control device capable of reducing the torque ripple by synchronizing the output timing of the PWM control signal with the sampling timing of the rotational position information of the brushless servomotor.

[Means for Solving the Problems] The present invention generates a PWM control signal in synchronization with the sampling timing of the rotational position information of the brushless servomotor.

FIG. 1 is a block diagram showing the configuration of the present invention.

That is, the present invention relates to a resolver in which a rotating shaft of a motor is coupled to a rotating shaft of a motor M, and a resolver excitation unit 2 for exciting a stator winding of the resolver.
A detection unit 5 for inputting a resolver detection signal to generate a synchronization signal and detecting motor rotation position information; a position calculation unit 6 for calculating a motor rotation position based on the motor rotation position information; The power supply to the motor is controlled based on the speed calculator 7 that calculates the motor rotation speed based on the rotation position information, the motor rotation position, the motor rotation speed, and the command signal that commands the physical quantity related to the motor rotation speed. In a motor drive control device comprising a PWM control signal generator 8 for generating a PWM control signal for driving the motor, and a motor driver 9 for driving a motor according to the PWM control signal, the PWM control signal generator 8 is The PWM drive signal is generated in synchronization with the synchronization signal generated by the detection unit 5.

The resolver 1 changes the rotational position of the brushless servomotor to
The rotational position sensor detects a phase difference between a resolver excitation signal and a resolver detection signal.

The excitation unit 2 includes a resolver excitation signal generation unit 3 and a power supply unit 4 that supplies power to the stator winding of the resolver according to the resolver excitation signal.
Waves and cos waves are generated in an analog or digital manner. To be digitally generated means, for example, reading out sin function data and cos function data stored in the memory according to the instruction of the counter and combining them.
The power feeding unit 4 is composed of an amplifier or the like that amplifies the resolver excitation signal and feeds it to the stator winding of the resolver.

The detection unit 5 generates a synchronization signal in synchronization with the rising and / or the falling of the resolver detection signal, and detects the phase difference between the resolver excitation signal and the resolver detection signal. Here, the phase difference can be obtained, for example, by digitally measuring the difference between the zero-cross points of the excitation signal and the detection signal with a counter. The counter can also be used as the counter of the exciting unit 2.

The position calculator 6 calculates the motor rotation position based on the detected phase difference.

The speed calculator 7 calculates the motor rotation speed based on the detected phase difference.

The PWM control signal generator 8 determines a PWM control signal from a physical quantity (motor rotation speed, motor rotation position, etc.) related to the motor rotation speed input from the outside, and the calculated motor rotation position and speed, This is output in synchronization with the synchronization signal.

The motor drive unit 9 is a DC-type transistor transistor or the like.
It is composed of an AC converter and supplies power to the motor M based on the PWM control signal.

[Operation] The excitation unit 2 generates an excitation signal and excites the stator winding of the resolver 1 according to the excitation signal.

The rotor of the resolver 1 rotates together with the rotary shaft of the motor M, and outputs a phase-modulated resolver detection signal to the detection unit 5.

The detection unit 5 detects a phase difference between the resolver excitation signal and the detection signal. The position calculation unit 6 calculates the motor rotation position based on the phase difference, and the speed calculation unit 7 calculates the motor rotation speed.

Based on these data and command signals from the outside, PW
The M control signal generator 8 outputs the PWM control signal in synchronization with the sampling of the detection signal.

The motor drive unit 9 drives the motor M according to the PWM control signal.

[Examples] Hereinafter, the present invention will be described based on specific examples.

(1) First Embodiment FIG. 2 is a block diagram showing the electrical components of this embodiment, and FIG. 3 is a flow chart for explaining interrupt processing in the CPU (FIG. 2). Also, FIG. 4 shows the second
It is a graph which shows the waveform of the signal wave of each point shown in the figure.

As shown in FIG. 2, in this embodiment, the exciting unit 2 is digitally configured, the counter 32 used in the exciting unit 2 is shared by the detecting unit 5, and the synchronization signal is a zero cross of the resolver detecting signal. This is the case in which it occurs in synchronization with the rising and falling from the point.

The excitation unit 2 includes an excitation signal generation unit 3 and a power feeding unit 4.

The excitation signal generator 3 includes an oscillator 31 (oscillates a 500 KHz clock pulse) and a counter 32 (8 bits; OO to
Up to FF, 512 μs is set as one cycle and counted every 2 μs), EPROM 33 (64 Kbits; sin function data table at even addresses OO to FF, and cos at odd addresses).
Each of them stores a function data table) and a D / A converter 34 (with dual 8-bit latch). Further, the power feeding unit 4 is composed of operation amplifiers 41 and 42, the output terminals of which are connected to the respective phases of the stator winding of a resolver (not shown).

That is, in the excitation unit 2, EP
The sin function data and the cos function data read from the ROM 33 are converted into analog signals by the D / A converter 34, amplified by the operation amplifiers 41 and 42, and output to the resolver.

The detection unit 5 includes a comparator 51, a resistor 52 connected to its output terminal, a capacitor 53, an Ex.OR gate 54,
It consists of a latch 55 (8 bits). That is, the resolver detection signal is waveform-shaped by the comparator 51, pulsed by the Ex.OR gate 54, and latched as a synchronization signal.
5 and CPU 70 (position calculation unit 6, speed calculation unit 7, PW
It is input to the M control signal generator 8). The output signal of the comparator 51 is input to the CPU 70 and rises as will be described later.
It is used as the fall judgment data. On the other hand, a rotation speed command signal (command corresponding to 0 to 3000 rpm corresponding to a voltage of 0 to 5 V) input by an external operation is amplified by the operation amplifier 71 and input to the CPU 70. CPU
70 outputs a PWM control signal based on the input data.

The motor drive unit 9 is composed of a buffer amplifier 91 and a transistor inverter 92, and the output terminals U, V, W of the transistor inverter 92 are respectively U of the motor.
Phase, V phase, W phase.

The operation of the apparatus of this embodiment will be described below.

A resolver (not shown) whose rotor is coupled to the rotating shaft of the motor and which is excited by the exciting unit 2 detects a detection signal (fourth).
FIG. B; FIG. 4A shows an excitation signal).

The detection signal is shaped into a square wave by the comparator 51 as shown in FIG. 4C, and then directly or indirectly inputted to the Ex.OR gate 54 through a delay circuit. The square wave is also input to the CPU 70.

The Ex.OR gate 54 outputs a pulse wave which is a synchronizing signal in synchronization with the rising and falling of the square wave as shown in FIG. 4D.

The pulse wave is input to the latch 55 and the count value at the pulse wave generation time is latched. The pulse wave is C
Input to the PU 70 to generate an interrupt.

The CPU 70 inputs the pulse wave and starts the interrupt processing shown in FIG.

First, at step 102, the pulse width modulation data TU _n-1 , TV _n-1 , TW obtained at time t _n-1 .
_n-1 is set in each of the built-in timers of the CPU 70. Next, at step 104, the time from the latch 55 to the time t _n
The count θ _n / 2 (the phase difference, which is the rotational position information, is given by θ _n ) is read. Then step 106
The rotational position W _n is calculated as w _n = (θ _n / 512) × 360 °. Next, at step 108, it is determined whether the pulse wave at time t _n is generated by the rising of the detection signal or the falling of the detection signal. This can be determined by whether the output level of the comparator 51 is high level or low level. If the result of the determination is a low level, it is determined that it is a trailing edge, the process proceeds to step 110, and w _n = w _n −180 ° is newly calculated to recalculate the rotational position, and then step 11
Go to 2. If the result of the determination is high, it is determined that it is a rising edge and the process directly proceeds to step 112. Step 112
Then, the rotation speed v of the motor is calculated. Rotational speed _{v n} at time _{t n} is given by _{v n = a × (w n} -w n-1). Here, a is a constant. Next step 1
Proceeding to step 14, the PWM time width data TU _n , T serving as the basis of the current value to be supplied to the U phase, V phase, and W phase of the motor.
V _n, TU and _{TW n n = b × (w} n -w n-1) × (sinθ n +1) TV n = b × (w n -w n-1) × {sin (θ n +12
0 °) +1} TW _n = b × (w _n −w _n−1 ) × {sin (θ _n +24
0 °) +1}, and the interrupt process ends. In addition, TU _n , T
V _n and TW _n give data of the next period, respectively.

PWM drive control of the brushless servomotor is performed as described above.

In this embodiment, the counter of the excitation unit 2 is shared by the detection unit 5 and is used for phase difference detection. Therefore, the number of parts is small and it is economical.

Further, the PWM control signal is generated in synchronization with the detection signal. Therefore, the sampling timing of the position data is synchronized with the calculation timing and the output timing of the PWM control signal, and the deviation of the motor power supply current due to the timing variation is small.

Further, the PWM control signal is generated in synchronization with both the rising and falling of the detection signal from the zero cross point. Therefore, the sampling period is 1/2 and the pulsation is small compared with the case of synchronizing only one side.

(2) Modified Example of the Above Embodiment FIGS. 5 and 6 are views showing a modified example of the above embodiment, in which predetermined portions in FIG. 2 are replaced with corresponding numerical circuits. .

FIG. 5 shows a case where the counter 32 is replaced with a 12-bit counter. If the exciting unit has 8 bits and the detecting unit has 12 bits, 4 bits are dedicated to the detecting unit.

In FIG. 6, the CPU 70 determines whether the CPU 70 has a rising edge or a falling edge.
This is a case of performing by inputting an interrupt signal of a type. In this case, a separate interrupt flow chart (not shown) corresponds to each interrupt signal.

[Effects] As described above, the present invention is, in short, the P of the brushless servomotor.
In the WM drive control, the PWM control signal is generated in synchronization with the sampling timing of the resolver detection signal.

As is clear from the description of the embodiment, according to the motor drive control device of the present invention, since there is no variation in the sampling timing of the motor rotation position data and the output timing of the PWM control signal, power feeding to each phase of the motor is possible. Therefore, the fluctuation in torque can be reduced.

Therefore, the motor drive control device of the present invention is most suitable for controlling a brushless servomotor that drives an NC machine tool or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. FIG. 2 is a block diagram showing the electrical components of the first embodiment, and FIG. 3 is a flow chart showing interrupt processing by the CPU in this embodiment. FIG. 4 shows the signal waveform at each point in FIG. 2, FIG. 4A is point A, B is point B, and C.
Represents point C, D represents point D, and E represents point E, respectively. FIGS. 5 and 6 show a modification of the first embodiment, FIG. 5 shows the case where the counter is changed, and FIG. 6 shows the case where the rising / falling determination method is changed. DESCRIPTION OF SYMBOLS 1 ... Resolver 2 ... Excitation part 5 ... Detection part 6 ... Position calculation part 7 ... Speed calculation part 8 ... PWM control signal generation part 9 ... Motor drive part

Claims (3)

[Claims] 1. A resolver having a rotating shaft of a rotor coupled to a rotating shaft of a motor, a resolver exciting unit for exciting a stator winding of the resolver, and a resolver detection signal to generate a synchronizing signal, A detection unit that detects rotational position information; a position calculation unit that calculates a motor rotation position based on the motor rotation position information; a speed calculation unit that calculates a motor rotation speed based on the motor rotation position information; A PWM control signal generator that generates a PWM control signal for controlling power supply to the motor based on a position, a motor rotation speed, and a command signal that commands a physical quantity related to the motor rotation speed, and the PWM control signal In the motor drive control device including a motor drive unit that drives the motor according to the above, the PWM control signal generation unit is a synchronization signal generated by the detection unit. In synchronism with the motor drive control device, characterized in that for generating the PWM control signal. 2. The motor drive control device according to claim 1, wherein the synchronization signal is generated in synchronization with a rising edge and a falling edge of the resolver detection signal from a zero cross point. 3. The exciting unit has a counter used for digitally synthesizing the resolver exciting signal, and the detecting unit detects the resolver exciting signal and the resolver detecting signal, which are motor rotational position information, based on the count value of the counter. The motor drive control device according to claim 1, which detects a phase difference from a signal.