Patent ID: 7215559

Claim:
A method for reducing common mode voltage applied to a load by a drive, the drive including a rectifier linked between three AC supply lines and positive and negative DC buses that converts AC supply voltage to DC voltage across the DC buses and an inverter linked between the DC buses and a load, the rectifier providing a DC input voltage to the inverter wherein, during normal operation, the inverter is capable of generating maximum inverter output voltages given a specific DC bus voltage, the method comprising the steps of: controlling the inverter to supply output voltages to the load where the output voltages are substantially free of common mode voltage and such that the maximum inverter output voltage is lower than the maximum inverter output voltage during normal inverter operation and given a specific DC bus voltage; and controlling the rectifier to convert the supply voltage to DC voltage across the DC buses and so that the DC bus voltage is boosted to a level greater than the peak three phase AC input voltage.