CONTROL METHODS FOR THE SYNCHRONISATION 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 powe r converters 1a, 1b and 1c that can be used to interface to a supply network, ac busbar etc. Each power converter includes a network bridge 14 operating in accordan ce 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. T he method includes the step of providing the switching period of the PWM strate gy of each network bridge with a different time offset relative to a time datum su ch 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.< /SDOAB>