Patent ID: 8004803

Claim:
A variable speed drive system configured to receive an input AC voltage at a fixed AC input voltage and provide an output AC power at a variable voltage and variable frequency, the variable speed drive comprising: a converter stage comprising at least two semiconductor switches for each power phase of the AC power source, the converter stage connected to an AC power source providing the input AC voltage, the converter stage being configured to convert the input AC voltage to a boosted DC voltage; a DC link connected to the converter stage, the DC link being configured to filter and store the boosted DC voltage from the converter stage; an inverter stage connected to the DC link, the inverter stage being configured to convert the boosted DC voltage from the DC link into the output AC power having the variable voltage and the variable frequency; and a controller for interrupting fault current flowing to an input phase of the converter stage in response to at least one current sensor sensing a ground fault on an input of the converter stage wherein each of the at least two semiconductor switches comprising a pair of reverse blocking (RB) IGBTs inversely connected in parallel.