Motor control apparatus with insulation degradation detection device and insulation degradation detection method of motor

Abstract

The invention provides a motor control apparatus with an insulation degradation detection device and an insulation degradation detection method of the motor. According to the apparatus, a bootstrap circuit can be applied for the insulation resistance detection function of the driver circuit of a semiconductor switch. A voltage division circuit is arranged between one end of the negative DC output part and a ground line through the normally open switch circuit comprising relay contacts. When a breaker is off, the normally open switch circuit is in a close state through a detection operation control part. The detection operation control part carries out the detection operations as following: in a pair of transistors in an arm circuit in an inverter circuit, one is in a conductive state and the other is in a stop state through PWM signals of the same duty ratio, and the insulation resistance detection part detects the insulation resistance based on the division voltage output by the voltage division circuit and the DC voltage input to the inverter circuit.

Description

technical field [0001] The present invention relates to a motor control device provided with an insulation deterioration detection device for detecting insulation deterioration (abnormal drop in insulation resistance) of a motor, and a method for detecting insulation deterioration of a motor. Background technique [0002] The servo motor is driven by a motor control device including an inverter circuit controlled by PWM (Pulse Width Modulation). Even among machine tools, for machine tools that use cutting fluid for machining, the cutting fluid may sometimes adhere to the motor. Also, depending on the nature of the cutting fluid, there is a problem that the cutting fluid enters the inside of the motor, deteriorating the electrical insulation of the motor. As the electrical insulation of the motor gradually deteriorates, it will eventually lead to a short circuit to ground. If the motor is shorted to ground, it will trip the earth leakage circuit breaker or damage the motor ...

AI Technical Summary

Problems solved by technology

However, for the power supply of the semiconductor switch of the positive pole of the inverter circuit such as Figure 5 In the case of using a bootstrap circuit by installing a capacitor and a diode in the upper stage of the inverter circuit, since the power supply of the positive electrode is only in the ON state for a short time during the PWM operation, there is a possibility that it must be turned off before the insulation resistance is detected. The problem that the positive semiconductor switch cannot be used

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