Patent ID: 8174853

Claim:
A variable speed drive 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 connected to a three phase AC power source providing the input AC voltage, the converter being configured to convert the input AC voltage to a boosted DC voltage; a DC link connected to the converter, the DC link being configured to filter and store the boosted DC voltage from the converter; an inverter connected to the DC link, the inverter 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 filter comprising: a three-phase input capacitor bank comprising three capacitors connected in a wye configuration, each capacitor of the three capacitors being connected at a first end to one phase of the three phase AC power source and at a second end to a common point with the other two capacitors; a grounding capacitor connected between the common point and earth ground; and wherein the three-phase input capacitor bank is configured to filter line to ground voltages of the three phase AC power source to reduce or substantially eliminate high frequency distortion across the converter stage.