Motor power supply and method of controlling the same

A method of controlling a motor power supply comprising an AC power input part, a DC-conversion part which converts AC power from the AC power input part into DC power, an inrush current limiting resistance provided between the AC power input part and the DC-conversion part, and an overvoltage-protection switching part connected with the DC-conversion part in parallel, the method comprising:

• charging the DC-conversion part when power is initially supplied via the inrush current limiting resistance;
• sensing a voltage charged in the DC-conversion part;
• and
• switching the overvoltage-protection switching part alternately On/Off when the sensed voltage is higher than a first predetermined voltage value, to reduce the voltage charged in the DC-conversion part by returning energy stored in the DC-conversion part toward the AC power input part.

A motor power supply for supplying an AC motor with power provided from an AC power source through an inverter, the motor power supply comprising:

• a DC conversion circuit which converts power from the AC power source to DC power and outputs the DC power to the inverter;
• a sensor which senses a voltage at an output of the DC conversion circuit;
• an overvoltage protection circuit which returns energy from the DC conversion circuit to the AC power source if the sensed output voltage exceeds a first predetermined value;
• and
• a resistance selectively connectable between the AC power source and the DC conversion circuit.