Patent ID: 8336323

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 DC voltage; a DC link connected to the converter stage, the DC link being configured to filter and store the DC voltage from the converter stage; and at least one inverter stage connected to the DC link; a motor connectable to the compressor for powering the compressor; and a controller configured to control switching in the converter stage and the inverter stage, the controller configured to apply randomized pulse width modulation to vary the switching frequency of transistors in the converter stage and the inverter stage at each switching cycle.