JPS5970193A - Controller for motor by width modulation pulse - Google Patents

Abstract

PURPOSE:To exclude an analog unit from a servo system of a motor by controlling a power amplifier by a signal superposed with a pulse-width formed speed command and an analog feedback signal as a pulse width data. CONSTITUTION:A pulse width converter 21 converts a digital speed command to a pulse width data 22. A synchronizing sawtooth wave generator 241 generates a positive oscillation output 2412 synchronized with the pulse 22 and a negative oscillation output 2411. The motor current of a load motor 10 and a speed signal are combined to become a current/speed feedback signal 4. When the signal is positive, it is compared with the oscillation output 2411, and when negative, it is compared with the oscillation output 2412. The outputs of comparators 242, 243 are outputted via a multiplexer by the pulse 22. The output 2470 of the multiplexer and the pulse 22 are calculated by an exclusive OR gate 25, and the combined wave 26 is used as a control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention converts the speed command into an e-pulse width and inputs an analog feedback signal of the speed current to this. 8 1 is n A speed command device that issues a bit digital speed command, 2 is a D that converts the digital speed command into an analog signal.
/A converter, 3 is an analog speed command, 4 is a current feed from the load motor, 5 is an operational amplifier, 6 is a triangular wave oscillator, 7 is a comparator, 8 is a width modulation pulse, 9 is, for example, a transistor bridge 10 is a load motor.

This uses an operational amplifier 5 to calculate the speed command 3 of the analog voltage and the analog feedback signal 4 of the speed current, and changes the pulse width by comparing it with a triangular wave via the comparator 7. This is known as an e-pulse width modulation (PWM) type transistor drive circuit. The speed command is output as an analog voltage signal 3 using a D/A converter 2.

By the way, this D/A converter 2 often becomes functionally defective, and is problematic from both a reliability and a cost perspective.

Furthermore, although digitization methods have been considered up to now, analog feedback signals are A/D converted and processed as bit data, resulting in system,
This led to an increase in the number of parts and costs, making it impractical.

Here, the present invention overcomes the deficiencies of the two conventional devices and makes it possible to perform calculations in units of pulse width as the calculation data, and calculates the speed command as it is digitally.
It is an object of the present invention to provide a device for controlling a transistor drive circuit by performing ξ pulse width modulation.

FIG. 2 is a block diagram showing the requirements of the configuration of one embodiment of the present invention.

21 is a pulse width conversion circuit, 22 is data obtained by converting a speed command into a pulse width, 23 is a synchronous PWM circuit, 24 is for its calculation, power, 25 is an exclusive OR circuit, and the station is a PWM control signal output. be.

In the present invention, after modulating a digital speed command into data 22 of ξ pulse width, the current/velocity feedback signal 24 modulated to ξ pulse width is superimposed in an exclusive □OR circuit 5. This is to obtain a drive signal 26 for the transistor 9.

Now, we will explain the details of each part.

The n-bit speed command is input to the pulse width conversion circuit 21 as shown in FIG. 3, and the n-bit value is converted into pulse width data 22 according to the pulse width duty.

If n == s btt, decimal, fO (00H in hexadecimal) is duty 50%, 1
+127 in 0 base (7.F H in hexadecimal) is duty 7
5%, -128 in decimal (80H in hexadecimal) is duty 25%
, data 22 converted to e-rus width (command/ni-rus)
is obtained.

This command pulse η is input to an exclusive OR circuit 5 forming a gate and a synchronous PWM circuit.

A block diagram showing the configuration of the synchronous PWM circuit is shown in FIG.

241 is a synchronous sawtooth wave generation circuit (2411, 2412
is its output), 242 and 243 are operational amplifiers (both form a comparator), 244 is an inverter, and 24
5, 246, and 247 are NAND (these form a multiplexer, and 2470 is its output layer 1, 5
The figure is a detailed internal block diagram of the sawtooth wave generation circuit.

501 and 503 are analog switches (their output turns on contacts 501a and 503a), 502 is an inverter, 504, 505, and 506 are operational amplifiers, 507°, 509, and 510 are resistors, and 508, 512
is a capacitor, ■□ is a reference voltage of the generated sawtooth wave, and Ov is a zero potential.

FIG. 6 shows waveform diagrams of various signals from normal rotation to reverse rotation of the load motor.

The synchronous PWM circuit 24 consists of a synchronous sawtooth wave generating circuit 241 and a connominator gate circuit.

Then, the input finger/ξ pulse n for each synchronous PWM circuit is input to the synchronous sawtooth wave generation circuit 241.

This output can be achieved by obtaining a positive oscillation output A 2412 and a negative oscillation output B 2411 synchronized with the command pulse 22.

・The period saw and the gigi wave generation circuit 241 are composed of switching elements (analog switches 501 and 503), a separator (operational amplifiers 504 and 506, and capacitors 5082 and 512).
), the oscillation output becomes zero by shorting the integration capacitors 508 and 512 of the integrator with the command nolse 22, and integration is performed by opening them. By repeating this, the modified sawtooth wave oscillation output A・2411 and oscillation output B・2412 are obtained, and the sawtooth wave reference voltage RF and F are positive or negative, and the oscillation outputs A-B are different. .

The motor current of the load motor 10 and the speed fee R notch detected by the speed generator (not shown or not) are combined to form a current/speed fee pack signal 4, and when the value is positive, the oscillation output A. When 2411 is negative, it is compared with oscillation output B.2412.

In FIG. 6, the negative feedback signal 4 is compared with the oscillating output B 2412 to obtain the output of the converter ξ-lator 242. This output is output via a multiplexer (Nands 245, 247) based on the command pulse 22.

The output multiplexer output 2470 enters the exclusive OR gate 5 and performs a superposition operation with the command pulse 22 to obtain a composite wave 26.

If we look at the feed para, 1 signal 4 and the output of the composite wave, we can see that when the signal 4's signal 4 increases in noise, the multiplexer output 2470 increases proportionally, and the exclusive OR with the command) e pulse 22. After the calculation in step 5, the duty of the composite wave 26 is reduced.

This is equivalent to PWM in a conventional circuit, and by inputting it to a transistor pace drive circuit (not shown), a servo drive system in which everything from commands to 4-speed drive is digitized is completed.

Thus, according to the present invention, it can be said that the analog part is eliminated from the motor servo system, and the path to direct digital servo has been opened, and the calculation of digital command pulses and feedback signals is cost-effective. This greatly contributes to improving the reliability of calculations.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional device, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a characteristic diagram of the ξ pulse width duty corresponding to the numerical value of the command pulse, and FIG. 5 is a block diagram showing the configuration of the synchronous PWM circuit, FIG. 5 is a wiring diagram showing internal details of the synchronous sawtooth wave generating circuit, and FIG. 6 is a time chart showing waveforms of various parts in this embodiment. 1...Speed command device, 2...D/A controller, 3
...Analog multiple voltage signal of speed command, 4.Current/speed feed note signal which is a composite of the motor current of the load motor and the motor speed, 5..Operation amplifier, 6..
・Triangular wave oscillator, 7... Comparator, 8... Width modulation pulse, 9... Power amplifier (transistor bridge circuit)
, 10... Electric motor (load), 21... Pulse width conversion circuit, 22... Data obtained by converting the speed command into pulse width, n... Synchronous PWM circuit, 24... Synchronous PWM
Calculated output of the circuit (current/speed feedback signal modulated to ξ pulse width) 6... Exclusive physical sum circuit 1.26.
... PWM control signal output (drive signal), 24
1... Synchronous sawtooth wave generation circuit, 2411... Its oscillation output A12412... Its oscillation output B, 24
2, 243... operational amplifier, 244... inverter, 245, 246, 247... Nando,
2470...Multiplexer output, 501, 50
3...Analog switch, 501a, 503
a...The contact point, 502..."In-no-ta, 5σ
4, 505, 506... operational amplifier, 507,
509510 =-・Resistance, 508, 512-:y
y capacitor, vRFF ``'Nokomoli wave reference voltage, Ov・
...Zero potential.

Claims (1)

[Claims] 1. A device for driving the electric motor in response to a width adjusted by a foot pulse signal from the electric motor; 2. First and second pulses synchronized with the command pulse; A synchronized sawtooth wave generation circuit that generates eight sawtooth wave signals, and first and second comparisons that compare the first and 20th sawtooth nine wave signals with the feedback signal, respectively. a multiplexer that generates a signal having a pulse width corresponding to the magnitude of the foot nosec signal from the command, the e-pulse, and the outputs of the first and second comparators; An electric motor-like control device using width modulation and ZORS, comprising an exclusive OR circuit that inputs an output signal of a multiplexer, and the motor is controlled by the output of the exclusive OR circuit. .