Control methods for the synchronisations and phase shift of the pulse width modulation (PWM) strategy of power converters

摘要

The present invention provides a method of controlling a plurality of power converters (1a... 1c) that can be used to interface to a supply network, ac busbar etc. Each power converter includes a network bridge (14) operating in accordance with a pulse width modulation (PWM) strategy having the same switching period and which causes at least one unwanted harmonic in the supply network voltage. The method includes the step of providing the switching period of the PWM strategy of each network bridge with a different time offset relative to a time datum such that the at least one unwanted harmonic in the supply network voltage is at least partially cancelled. Two alternative ways of providing the time offset are described.