KR830001751A - Induction motor drive device - Google Patents

Abstract

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Description

Induction motor drive device

This content is subject to disclosure, so the full text is not included.

4 is a circuit block diagram of an induction motor driving apparatus according to the present invention. Fig. 7 is an embodiment of the amplitude control circuit of Fig. 4, and Fig. 9 is another embodiment of the amplitude control circuit of Fig. 4;

Claims (8)

Inverter for converting DC voltage into three-phase AC voltage, induction motor driven by three-phase AC voltage, speed command means for instructing the induction motor to rotate at the commanded speed, and means for detecting the actual speed of the induction motor Including, in the induction motor driving device whose actual speed is consistent with the commanded speed by controlling the effective value of the frequency and the three-phase AC voltage, generating a deviation signal based on the deviation between the commanded speed of the induction motor and the actual speed. A deviation signal generating means for generating a torque limit signal, a torque limit signal generating means for generating a torque limit signal, an amplitude control means for controlling the amplitude of the deviation signal based on the appearance of the torque limit signal, positive or negative corresponding to the rotation direction of the induction motor A slip signal generating means for generating a slip signal having a constant voltage of, an adding means for adding the output of the amplitude control means to the slip signal, and generating a three-phase rectangular wave signal of a frequency corresponding to the output of the adding means A square wave signal generating means for multiplying the output of the amplitude control means by the output of the adding means, and for modulating each signal width of the three-phase square wave signal according to the magnitude of the output signal of the multiplying means It is composed of pulse width modulating means, and the effective value of the two-phase AC voltage is adjusted by controlling the inverter based on the pulse-width modulated three-phase rectangular signal, and the torque of the induction motor in the low-speed region controls the amplitude of the speed deviation signal. By doing so, the induction motor driving device is limited to below the specified value. A patent including a limiter for limiting the speed deviation signal to the amplitude control means below the clamp voltage, a clamp voltage set circuit for setting the clamp voltage, and a switch circuit for enabling the function of the limiter by the torque limit signal An induction motor drive device according to claim 1. An induction motor according to claim 1, comprising a voltage divider capable of dividing the voltage of the speed deviation signal by the amplitude control means and changing the divided voltage ratio, and a switch circuit capable of activating the function of the voltage divider by means of a torque limit signal. drive. An induction motor driving device according to claim 1 or 2 or 3, wherein the orientation signal generated when the tool is installed on two spins of the machine is a torque limit signal. An amplitude control circuit for the pulse width modulating means to control the amplitude of each square wave signal based on the output of the multiplication means, a sawtooth wave generator circuit for generating a sawtooth signal whose frequency is greater than the frequency of the square wave signal, and the amplitude An induction motor according to claim 1 consisting of a comparator that compares the level of each square wave signal whose amplitude is controlled by the control circuit and the level of the sawtooth signal, and generates a pulse width modulated square wave signal based on the level comparison result. drive. In addition, a full-wave rectifier for full-wave rectification of the three-phase AC voltage, and a low-pass filter for leveling the ripple held in the output of the full-wave landing device in which the output of the multiplication means is modified by the output. An induction motor drive device according to clause 5. A voltage-frequency converter for generating a pulse train whose frequency is proportional to the output voltage of the adding means, and a three-phase response to the pulse train to provide a three-phase rectangular signal from each step of the square wave signal generating means An induction motor drive device according to claim 5 having a ring counter. ※ Note: It is disclosed according to the contents of the initial application.