JPH02159993A - Reference current waveform generator of synchronous ac servo-motor driving apparatus - Google Patents

Abstract

PURPOSE:To facilitate speed detection and speed control of every section obtained by dividing one turn by a method wherein the individual speeds of the respective sections are determined in accordance with a rotation angle detecting signal obtained by supplying a voltage corresponding to a half of a DC source voltage and the voltage of an artificial neutral point to a comparator and a voltage value detecting signal synchronized with the rotation angle detecting signal. CONSTITUTION:A judgement device 15 is an A/D converter with a sample hold which maintains an artificial neutral potential when the detection output of a position detector 14 is changed and transmits the artificial neutral potential value to a controller 7. A microcomputer is used as the controller 7 and, when the signal is inputted from the position detector 14, the input from the judgement device 15 is compared with a threshold to obtain a right-or-wrong judgement signal and sectional speeds are detected and PWM signals given to transistors 1-6 are determined. With this constitution, the accuracy of detecting speeds of the respective sections obtained by subdividing one turn of the motor can be improved and the speeds of the respective sections can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reference current waveform generation circuit for the motor drive device, which enables smooth movement of a synchronous AC servo motor.

(Prior Art) An example of the configuration of a drive device for a synchronous AC servo motor is shown in FIG. Pulses A and B, which are two-phase square wave signals from a pulse encoder 41, are transmitted to a speed detector 1 consisting of a frequency/voltage converter.
2 is input. Then, this speed detector 12 outputs a speed feedback signal n to the adder 10. In addition to this speed feedback signal n, the adder 10 receives a speed command value n.
These deviations (n·-n) are outputted as a torque command τ through the speed control amplifier 11.

On the other hand, the reference current waveform generation circuit 21' receives the magnetic pole position detection signals U and V output from the pulse encoder 41.

W and pulses A and B, which are two-phase square wave signals, are input,
Output reference current waveforms a, b, and a. Further, the torque command τ・ and the reference current waveforms a, b, and c are transmitted to a multiplier 20a.
, 20a and 20c, respectively. and,
Each multiplier 20a to 20c converts the multiplied value of each input signal into current commands iu・(=τ・・a), iv・(=τ・・b Li
Output to the current control system 30 as w (=...C),
The current control system 30 controls the motor currents iLl, iV, iw based on the current commands iu., iv", iw-.

FIG.
Conventional reference current waveform generation circuit 21 shown in No. 5789
FIG. The operation of the circuit shown in FIG. 3 will be explained below with reference to the circuit diagram shown in FIG. 3 and the waveform diagram shown in FIG.

First, the switch 215 is set to the square wave generator 210 side, and when the control power is turned on (Fig.
) Magnetic pole position detection signals U, V from pulse encoder 41
, W are input to a square wave generator 210 and an angular origin detector 212. And, the square wave generator 210 is shown in Fig. 5.
Three-phase square waves are output during the period from to tl, and these square waves become the outputs (reference current waveforms a, b, c) of the reference current waveform generation circuit 21'.

Next, when the magnetic pole of the rotor of the motor 40 rotates and comes to a predetermined reference position, the angle origin detector 212 detects the angle origin signal OR.
G (time t1 in FIG. 5), and this OR
G resets the counter 213 and sets the flip-flop 214.

By the above reset, the counter '213 outputs a phase angle signal θ to the sine wave generator 211 according to the count value based on the input pulses A and H. Further, with the above setting, the flip-flop 214 sets the switch 215 to the sine wave generator 211 side, and switches the outputs a, b, and Q of the reference current waveform generating circuit 21 from three-phase square waves to sine waves.

(Problem to be Solved by the Invention) By the way, the three-phase square wave from the square wave generator 210 is generated until the magnetic pole position of the motor 40 is detected, that is, until the counter 213 recognizes the ORG. 5, period to=ti) is output.

Torque ripple occurs in the motor due to driving by this three-phase square wave. For these reasons, it is ideal that the immediate operation period using a square wave is short. However, in the conventional reference current waveform generating circuit 21', the square wave is driven for an electrical angle of 360 degrees at worst. During this time, there is an inconvenience that a torque ripple with a frequency six times the inverter frequency occurs.

The present invention has been proposed to solve the above problems, and its purpose is to change from square wave drive to sine wave drive or pseudo sine wave drive within a maximum electrical angle of 60° using a magnetic pole position detection signal. An object of the present invention is to provide a reference current waveform generation circuit for a synchronous AC servo motor drive device that enables smooth operation of a servo motor by switching to immediate operation.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic pole position that identifies a region every 60' electrical angle output by an encoder provided on the rotor shaft of a synchronous AC servo motor. Based on the detection signal and two-phase pulses that are 90° out of phase with each other,
After the control power is turned on, a three-phase square wave current having a phase difference of 120 degrees electrical angle is passed through the three windings of the motor for a maximum period of 60' electrical angle, and after passing the switching point of the magnetic pole position detection signal, the Generating a reference current waveform for a synchronous AC servo motor drive device that calculates the rotation angle of a rotor from a magnetic pole position detection signal and two-phase pulses, and drives the motor by passing a three-phase sinusoidal current corresponding to the rotation angle. The circuit includes an edge detector that detects rising and falling edges of the magnetic pole position detection signal, and an edge detection signal from the edge detector that counts the two-phase pulses and outputs a first angle signal. a counter that resets a count value by; a rotation direction detector that detects the rotation direction of the rotor based on the magnetic pole position detection signal and the edge detection signal; and a rotation direction detector that detects the rotation direction of the rotor based on the magnetic pole position detection signal and the rotation direction detector. an angle table that outputs a second angle signal based on the direction signal; a square wave generator that outputs a three-phase square wave signal synchronized with the magnetic pole position detection signal;
a sine wave generator that outputs a three-phase sine wave signal or a three-phase pseudo sine wave signal based on the added value by the adder, and the square wave generator based on the edge detection signal. and a switch for switching between the output of the sine wave generator and the output of the sine wave generator.

(Function) In the present invention, before the edge detector detects the first rising or falling edge of the magnetic pole position detection signal, that is, in the range where the rotation angle of the motor is within 60" electrical angle, the switch activates the square wave generator. The output of the reference current waveform generation circuit becomes a three-phase square wave according to the logic of the magnetic pole position detection signal.

When the motor rotates at a maximum of 60 degrees electrically and the edge detector detects the edge of the first magnetic pole position detection signal, it outputs an edge detection signal. Further, the one-rotation direction detector outputs a rotation direction signal determined from the magnetic pole position detection signal and the edge detection signal. At the same time, the counter that was counting the two-phase pulses is reset and the flip-flop is set. Then, a switch is changed by the output of this flip-flop, and the output of the reference current waveform generation circuit is changed from a three-phase square wave to a three-phase sine wave or a three-phase pseudo sine wave. The three-phase sine wave or three-phase pseudo sine wave at this time is based on the sum of the first angle signal from the counter and the second angle signal obtained from the angle table based on the magnetic pole position detection signal and rotation direction signal. The synchronous AC servo motor is driven smoothly by this.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure is a circuit diagram showing a reference current waveform generation circuit 21,
Pulses A and B, which are two-phase square wave signals, and magnetic pole position detection signals U, V, and W are inputted from the input terminal pDP' in the figure, and reference current waveforms a, b, and c are outputted from the output terminal q. Ru.

Now, the pulse encoder 41 in FIG.
The area of each 0° is identified and the magnetic pole position detection signal U is generated.

(2), W, and pulses A and B whose phases are shifted by 90 degrees from each other are output.

First, pulses A and B from an input terminal p are input to a counter 1 that counts the number and outputs a first angle signal θC. In addition, the signals U, V, and W from the input terminal p' are sent to an edge detector 2 that outputs edge detection signals at all of these rising and falling edge points, and detects the rotational direction of the rotor.
In addition to being input to a rotation direction detector 3 which stores and outputs a rotation direction signal F7k, and a square wave generator 4 which outputs signals a, b, and Q in synchronization with the signals U, V, and W, respectively,
It is input to the angle table 5 which outputs the second angle signal θ0.

The edge detection signal output from the edge detector 2 is input to the set terminal of the flip-flop 6, the reset terminal of the counter 1, and the rotation direction detector 3. Further, the output terminal of the rotation direction detector 3 is input to the angle table 5, and the outputs of the counter 1 and the angle table 5 are input to the adder 7, and the output θ of this adder 7 is input to the sine wave generator 8. has been entered.

The output of the sine wave generator 8 and the output of the square wave generator 4 are input to a switch 9 having a switching function, and the output of the flip-flop 6 is input to a switching selection terminal of this switch 9.

The operation of this reference current waveform generation circuit 21 will be explained below with reference to the operation waveform diagram of FIG. 2.

First, before the rising edge or falling edge of any of the signals U, V, and W is input to the edge detector 2,
The switch 9 is selected so that the output from the square wave generator 4 becomes the output of the reference current generation circuit 21. Therefore, the reference voltage generation circuit 21 outputs three-phase square wave signals from the square wave generator 4 according to the logic of the signals U, V, and W as reference current waveforms a, b, and a. During this time, counter 1 is pulse A.

Counting B.

Next, when the edge detector 2 detects a rising edge or a falling edge of any of the signals U, V, and W, the edge detector 2 outputs an edge detection signal at time tEo in FIG.

On the other hand, this edge detection signal causes counter 1 to output pulse A.
, B are reset every 60 degrees of electrical angle, and the rotation direction detector 3 receives the edge detection signal and the signals U, V, W.
Detects and stores the rotation direction determined by the signal F/R.
In addition to outputting to the angle table 5, the flip-flop 6
outputs a switching signal to the switch 9 to switch the reference current waveform a l b IC from a three-phase square wave to a three-phase sine wave.

Further, the angle table 5 includes the signal F/R and the signal U.

(2) A second angle signal θ according to the W input. is output to the adder 7. Note that Table 1 shows the data contents stored in the angle table 5.

Table 1 Addition l17 is the first angle signal θ0, which is the output of counter 1, and the second angle signal θ. This added value θ (20010.) is output to the sine wave generator 8. Then, the reference current waveform generation circuit 21 outputs a three-phase sine wave, which is the output of the sine wave generator 8 based on this added value θ, as reference current waveforms a, b, and c via the switch 9.

As described above, in this embodiment, the magnetic pole position detection signal U.

The three-phase square wave signal is used until the first edge of v and W is detected, and after the edge is detected, the signal is switched to three-phase sine wave drive by simply driving the square wave for a period of up to 60 degrees in electrical angle. It becomes possible to obtain servo characteristics.

Note that although the above embodiment has been described as driving with a sine wave, it does not necessarily have to be an accurate sine wave, and may be a *similar sine wave. Also, the reference current waveform is created for three phases, but
You can create only 2 phases and create the remaining 1 phase from the other 2 phases, or you can create only the reference current waveforms for 2 phases, then create the current commands for 2 phases, and then create the current for the remaining 1 phase. Commands may be generated from the other two phases.

(Effects of the Invention) As described above, according to the present invention, the magnetic pole position detection signals U, V
Since all rising and falling edges of , W are detected and switched to sine wave drive, the period until switching from three-phase square wave to three-phase sine wave is a maximum of 60 degrees in electrical angle, making it easier to use than conventional drive methods. Compared to this, the servo motor can be driven more smoothly. Furthermore, after the above switching, the angle table data based on the magnetic pole position detection signal and edge detection signal and the counter value based on the two-phase pulse are added, and three-phase sine wave driving is performed based on this added value. Therefore, there are effects such as being able to drive the motor smoothly.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
Operation waveform diagrams of each part to explain the action of the embodiment shown in the figure,
FIG. 3 is a configuration diagram of the motor drive device. FIG. 4 is a circuit diagram showing the prior art, and FIG. 5 is an operation waveform diagram for explaining the operation of the prior art shown in FIG. 1...Counter 2...Edge detector 3.
...Rotation direction detector 4...Square wave generator 5...
Angle table 6...Flip-flop 7...
Adder 8...Sine wave generator 9...Switch 21...Reference current waveform generation circuit

Claims (1)

[Claims] A magnetic pole position detection signal that identifies a region of every 60 degrees of electrical angle output by an encoder provided on the rotor shaft of a synchronous AC servo motor, and two-phase pulses whose phases are shifted by 90 degrees from each other. Based on this, the maximum electrical angle is 60° after the control power is turned on.
During the period, three-phase square wave currents with different phases of 120 electrical degrees are passed through the three windings of the motor, and after passing the switching point of the magnetic pole position detection signal, the rotation starts from the magnetic pole position detection signal and the two-phase pulse. A reference current waveform generation circuit for a synchronous AC servo motor drive device that calculates a rotation angle of a child and drives the motor by passing a three-phase sine wave current corresponding to the rotation angle, the magnetic pole position detection signal an edge detector that detects rising and falling edges of the pulse, a counter that counts the two-phase pulse and outputs a first angle signal and resets a count value by an edge detection signal from the edge detector; a rotational direction detector that detects the rotational direction of the rotor based on the magnetic pole position detection signal and the edge detection signal; and a second angle signal based on the magnetic pole position detection signal and the rotational direction signal from the rotational direction detector. an angle table to output, a square wave generator to output a three-phase square wave signal synchronized with the magnetic pole position detection signal, an adder to add the first angle signal and the second angle signal, and the adder. a sine wave generator that outputs a three-phase sine wave signal or a three-phase pseudo sine wave signal based on the added value, and switching between the output of the square wave generator and the output of the sine wave generator based on the edge detection signal. A reference current waveform generation circuit for a synchronous AC servo motor drive device, comprising a switch.