Motor drive device including insulation deterioration detection function and insulation resistance detection method of motor

摘要

A motor drive device of the present invention includes: a rectification circuit configured to rectify an AC voltage; a power source unit configured to smooth a DC voltage by a capacitor; an inverter unit configured to drive a motor by converting a DC voltage into an AC voltage; a current detection unit configured to measure a current flowing through a resistor which is connected to a coil of the motor and the capacitor; a voltage detection unit configured to measure a value of a voltage across the capacitor; a second switch that grounds the capacitor; and an insulation resistance detection unit configured to detect an insulation resistance value of a motor by using two sets of a current value and a voltage value measured in two states where the second switch is turned off and turned on.

主权项

1. A motor drive device, comprising:
a first switch; a rectification circuit configured to rectify an alternating-current voltage supplied from an alternating-current power source via the first switch into a direct-current voltage; a power source unit comprising a capacitor and configured to smooth the direct-current voltage rectified by the rectification circuit by the capacitor; an inverter unit comprising a semiconductor switching element and configured to drive a motor by converting the direct-current voltage smoothed by the power source unit into an alternating-current voltage by a switching operation of the semiconductor switching element; a resistor, one end of which is connected to a coil of the motor and the other end of which is connected to a first terminal of the capacitor; a current detection unit configured to measure a current value of a current flowing through the resistor; a voltage detection unit configured to measure a voltage value of a voltage across the first terminal and a second terminal of the capacitor; a second switch that grounds the second terminal of the capacitor; and an insulation resistance detection unit configured to stop the operation of the motor, turn off the first switch, and detect an insulation resistance value of an insulation resistance of the motor, by using two sets of the current value and the voltage value measured in a state where the second switch is turned off and in a state where the second switch is turned on, wherein an influence of a leakage current of the semiconductor switching element is eliminated by using the two sets of the current value and the voltage value measured in the state where the second switch is turned off and in the state where the second switch is turned on, and wherein the insulation resistance is a resistance between the coil of the motor and the ground.