JPS63107479A - Regenerative control system - Google Patents

Abstract

PURPOSE:To eliminate a transformer in a regenerative control system thereby to be able to reduce the size of control equipment by digitally obtaining a sine curve having the same phase as a voltage between the phases of an input AC line by a processor. CONSTITUTION:A zero-cross signal is input from an edge detector 2 to a processor 3. The processor 3 reads out the value of a U-phase counter of counters 5. Then, the processor 3 reads out the pattern of a corresponding sine curve from the sine curve table of an ROM 6, and writes the value in a port 7. Similar operation is executed in a V phase. Thus, the processor 3 reads out the value of the sine curve table of the ROM 6 each time the counter 5 counts, and D/A- converts the output to obtain a sine curve having the same phase as an input AC line. In a W phase, it can be obtained by combining them from the U and V phases by a W-phase composite circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a regeneration control method for a servo motor, and particularly to a regeneration control method configured to digitally obtain a regenerative voltage waveform.

[Conventional technology]

It is widely known that regeneration control is performed during deceleration of a servo motor, and in particular, in order to increase regeneration efficiency, it is proposed in Japanese Patent Application No. 61-57900 that the regenerative voltage waveform be made in phase with the phase-to-phase voltage of the input AC line. The application has been filed by.

[Problem that the invention seeks to solve]

However, in such a system, in order to obtain the phase-to-phase voltage of the input AC line, a dedicated transformer is prepared to obtain the sine wave in an analog manner. For this purpose, a special transformer is required, and the cost of the transformer itself cannot be ignored.
Further, wiring for this purpose is required, making it difficult to miniaturize the control equipment.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a regeneration control system configured to digitally obtain a regenerative voltage waveform.

[Means for solving problems]

In order to solve the above problems, the present invention compares the correlation voltage of the input AC line and the regenerative feedback voltage of the servo motor, and calculates the product of the difference voltage and the phase-to-phase voltage of the input AC line to obtain the regenerative current. In the regeneration control system configured as above, a zero-crossing point detection circuit detects the zero-crossing point of the phase-to-phase voltage of the input AC line, a counter that performs a counting operation at fixed time intervals using an oscillator of a fixed frequency, and a sine curve storage means storing a table having a sine curve corresponding to the phase-to-phase voltage; each time the counter counts from the zero-crossing point signal, the value is read from the sine curve storage means; A voltage waveform equivalent to the phase-to-phase voltage of the input AC line is obtained by converting the voltage waveform, the product of the voltage waveform and the difference voltage is calculated, and the regenerative current is controlled by the signal obtained by the product. A regenerative control method was adopted.

[Function] □ The counter reads the value from the sine curve table at regular intervals from the zero-crossing point of the input AC line, converts this value from DA to obtain a sine curve that is in phase with the phase-to-phase voltage of the input AC line, and converts this value to the sine curve. The product of the sine curve and the difference voltage between the regenerative feedback voltage of the servo motor and the phase-to-phase voltage of the input AC line is calculated, and the regenerative current waveform is controlled by that waveform.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention. In the figure, 1 is a zero cross point detection circuit, which detects the zero cross point of the input AC line. 2 is an edge detection circuit;
The zero cross point of the zero cross point detection circuit 1 is shaped into a pulse waveform. A processor 3 controls the servo motor, but only the control related to this embodiment will be described here.

That is, in response to a pulse signal from the edge detection circuit 2, control described below is performed.

4 is an oscillator with a constant frequency, and its output is sent to counter 5.
It is connected to the. A counter 5 performs a counting operation at every fixed frequency of the oscillator 4, and is composed of three counters: U phase, ■ phase, and W phase. 6 is a ROM in which a sine curve table is stored. 7 is a port, into which output data from the processor 3 is written.

Reference numeral 8 denotes a deviation amplifier, which determines the deviation between the regenerative feedback voltage of the servo motor and the input AC line, and its output is connected to multiplication type DA converters 9 and 10. Numerals 9 and 10 are multiplication type DA converters, which DA convert the values of the sine curve table read from the ROM 6 by the processor 3 and simultaneously perform multiplication with the output ER of the deviation amplifier 8. The multiplication type DA converter 9 is for the U phase, and the multiplication type DA converter 10
is for V phase, and W phase is for DA converter 9 and DA converter 10.
are synthesized from the outputs of by a W-sum synthesis circuit.

21, 22 and 23 are computing units, 631 is a U-phase current amplifier, 32 is a ■-phase current amplifier, and 33 is a W-phase current amplifier, which calculates the difference between the regenerative current command value and the actual current value of each phase. The regenerative current is controlled and output according to the commands from the computing units 21, 22 and 23, respectively. CTI, C70 is a current detector, and its detected value is fed back to computing units 21 and 22. However, the W phase is synthesized by the synthesis circuit 34 from the outputs of the U phase and ■ phase current detectors.

Next, the operation of this embodiment will be described. FIG. 2 shows a partial flowchart of the operation of this embodiment.

81 to S13 in the figure indicate these steps.

The zero cross point signal from the edge detection circuit 2 is sent to the processor 3.
When input to , the following operations are performed.

[Step E]

The processor 3 reads the value of the U-phase counter of the counters 5.

[Step 2] The processor 3 converts the corresponding sine curve pattern into RO
Read from the sine curve table of M6 [Step 3] The processor 3 writes the value to the boat 7.

[Steps 11 to 13] The same operations as steps 1 to 3 above are performed for the V phase.

In this way, each time the counter 5 counts the value of the sine curve table in the ROM 6, it is written to the port 7 and the output is DA-converted, thereby obtaining a sine curve that is in phase with the input AC line. However, W
Regarding the phase, do not calculate it in this way, but from the U phase and ■ phase to W
The combination can be performed by the summation circuit 11.

Then, at the same time as the DA conversion, the output of the deviation amplifier, that is, the product of the difference between the regenerative feedback voltage of the servo motor and the phase-to-phase voltage of the input AC line, is calculated, and this signal is used to calculate the regenerative current that is in phase with the phase-to-phase voltage of the input AC and line. Obtainable.

In the above embodiment, DA conversion and multiplication were performed simultaneously, but of course, it is also possible to first perform AD conversion on the output of the deviation amplifier 8, perform multiplication in the processor 3, and then perform DA conversion.

〔Effect of the invention〕

As explained above, the present invention is configured to digitally obtain the sine curve in phase with the phase-to-phase voltage of the input AC line using a processor, so there is no need for a dedicated transformer, and furthermore, noise in the power supply line can be reduced. few.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a partial flowchart of one embodiment of the present invention. 1---1--Zero cross point detection circuit 3--Processor 5--Counter 6--ROM 8--Deviation amplifier 9-- D A converter

Claims (2)

[Claims] (1) In a regenerative control method configured to compare the phase-to-phase voltage of the input AC line and the regenerative feedback voltage of the servo motor, and calculate the product of the difference voltage and the phase-to-phase voltage of the input AC line to obtain the regenerative current, the input A zero-crossing point detection circuit that detects the zero-crossing point of the phase-to-phase voltage of the AC line, a counter that performs counting at fixed time intervals using an oscillator with a constant frequency, and a table that has a sine curve corresponding to the phase-to-phase voltage of the input AC line. and a sine curve storage means that stores a sine curve storage means, each time the counter counts from the zero cross point signal, reads the value from the sine curve storage means, converts the value into an AD converter, and converts the value into a value corresponding to the phase-to-phase voltage of the input AC line. 1. A regeneration control method, comprising: determining a voltage waveform of the voltage waveform, calculating the product of the voltage waveform and the differential voltage, and controlling a regeneration current using a signal obtained by the product. (2) The regeneration control method according to claim 1, wherein the product of the current waveform and the differential voltage is configured to be performed simultaneously with DA conversion.