Patent ID: 8217533
Filing Date: 2012-07-10
Classification: H02J,H02M,Y02E

Abstract:
1. A method of controlling a plurality of power converters that can be used to interface to an ac supply network, each power converter comprising a network bridge having ac terminals connected to the ac supply network, the network bridge operating in accordance with a pulse width modulation (PWM) strategy represented by a carrier waveform having the same switching period and which causes at least one unwanted harmonic in the supply network voltage, the method comprising the steps of: generating, by a first power converter, a time signal to act as a time datum; transmitting, by the first power converter, the time signal to at least a second power converter; and providing the switching period of the PWM strategy of each network bridge with a different time offset relative to the time signal to provide a different phase shift in the carrier waveform such that the at least one unwanted harmonic in the supply network voltage is at least partially cancelled.