CIRCUIT AND METHOD FOR REDUCING INRUSH CURRENT OF PHASE CONVERTER MOTOR

摘要

A method and circuit for starting a three-phase motor in a manner that reduces inrush current normally associated with starting an AC motor. The method uses the circuit to start the three phase motor gradually with three phase alternating current having relatively low frequency and gradually increasing the frequency up to or above the motor operating frequency over a period of time and then switching in a single phase alternating current supply to power the three phase motor.

主权项

1. A single phase to three phase converter, comprising:
a single phase VAC supply input and a VAC output; an AC direct relay coupled electrically in series between the single phase VAC supply input and the VAC output; a rectifier having a rectifier VAC input and a rectifier DC output, the rectifier VAC input coupled to the single phase VAC supply input; an inverter having an inverter circuit DC input, a plurality of inverter circuit switching inputs, and an inverter circuit three phase output, the inverter circuit DC input coupled to the rectifier DC output; an inverter contactor coupled electrically in series between the inverter circuit three phase output and the VAC output; and a controller having a plurality of inverter control outputs respectively coupled to the plurality of inverter circuit switching inputs; wherein a single phase VAC supply is connectable to the VAC output through the AC direct relay and the inverter circuit three phase output is connectable to the VAC output through the inverter contactor.