Patent ID: 9293921
Filing Date: 2016-03-22
CPC Classification: H02J,H02M,Y02E

Claim Text:
1. A method of controlling a plurality of power converters interfacing to an ac supply network, each power converter including a network bridge operating in accordance with a pulse width modulation (PWM) strategy and an individual controller, the method comprising: operating, the PWM strategy of the network bridge of each power converter, at a nominal switching frequency as determined by the controller based on an internal time of the controller; generating, by a stand-alone timing controller in communication with each individual controller of the network bridges, a common time signal; receiving the common time signal at the individual controller, and measuring and time-stamping the common time signal, via the individual controller based upon the internal time of the individual controller; adjusting, by the individual controller, the switching period of each of the network bridges in response to the variations of the common time signal as measured; varying, by the individual controller, a switching frequency of the PWM strategy responsive to a time-varying frequency of the supply network; and obtaining only integer harmonics of the time-varying frequency upon varying the switching frequency of the PWM strategy, and setting the time period of the common time signal to be equal to the reciprocal of the switching frequency.