INDUCTION ELECTRIC MOTOR OVERHEAT MONITORING METHOD, INDUCTION ELECTRIC MOTOR MONITORING DEVICE, AND INDUCTION ELECTRIC MOTOR CONTROL SYSTEM

摘要

Provided is an induction motor overheat monitoring method and device capable of detecting overheat of an induction motor only from a detection value of a current sensor without requiring many sensors as in a conventional case. First, resistance calculation relationship data indicating a relationship between a resistance and a feature amount at the time of starting of the induction motor and a determination reference value for determining overheating are stored in advance. At each starting during an operation period in which the motor is frequently started and stopped, a current of the induction motor is detected, a signal regarding a phase angle difference is calculated by obtaining a phase angle from the detected current, and a feature amount of the motor is calculated from the signal regarding the phase angle difference. Further, a resistance of the induction motor is calculated by using the feature amount of the motor and the resistance calculation reference data stored in advance. Then, a temperature of the induction motor is calculated from the resistance of the induction motor, and the calculated temperature of the induction motor and the determination reference value are compared to determine whether or not the motor is overheated.