Patent ID: 7957166

Claim:
A variable speed drive system configured to receive an input AC power at a fixed AC input voltage magnitude and frequency and provide an output AC power at a variable voltage and variable frequency, the variable speed drive comprising: a 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 an input filter; the input filter comprising: a three-phase inductor having three windings, wherein each winding of the three-phase inductor having a center tap dividing each winding into a pair of inductor sections; and a three-phase input capacitor bank having three capacitors connected in a wye configuration to the three center taps at one end, and to a common point at the opposite end; wherein the three-phase input capacitor bank is configured to substantially provide a short circuit for frequencies above a predetermined fundamental frequency for shunting frequencies above a predetermined fundamental frequency through the three phase capacitor bank, while passing the predetermined fundamental frequency to the converter stage.