Patent ID: 7405494
Filing Date: 2008-07-29
Classification: H02J,H02M

Abstract:
1. A method of operating a plurality of paralleled uninterruptible power supplies (UPSs), the UPSs including respective pulse-width modulation (PWM) power converter circuits coupled in common to an AC load bus, the method comprising: providing a phase reference corresponding to an AC voltage phase for the AC load bus, wherein providing a phase reference corresponding to an AC voltage phase for the AC load bus comprises providing respective sinusoidal reference signals at respective ones of the UPSs; and synchronizing PWM cycles of the PWM power converter circuits of each of the power converter circuits to the phase reference, wherein synchronizing PWM cycles of the PWM power converter circuits of each of the power converter circuits to the phase reference comprises synchronizing the respective PWM cycles of the UPSs to the respective sinusoidal reference signals and wherein synchronizing the respective PWM cycles of the UPSs to the respective sinusoidal reference signals comprises: