Patent ID: 7208891

Claim:
A drive system for a compressor of a chiller system, the drive system comprising: a variable speed drive, the variable speed drive being 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 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; and 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 motor connected to the inverter stage and powered by the output AC power from the inverter stage, the motor being connectable to a compressor of the chiller system to power the compressor; wherein the converter stage comprises a three-phase pulse width modulated boost rectifier having insulated gate bipolar transistors and is configured to maintain a boosted DC voltage greater than the input AC voltage when the input AC voltage falls below the fixed AC input voltage.