Dynamic frequency scaling to improve converter efficiency

A controller, suitable for medium to high power switching converters (1 kW to 1 MW), is proposed that dynamically changes the output PWM carrier frequency. The control objective is to optimise the choice of switching frequency so as to maximise overall converter efficiency, while providing a good transient performance. A range of control techniques which can determine when to change the PWM switching frequency are investigated. The practical limitations imposed by conventional PWM controllers and DSPs used in switching converter control are also considered.