Adaptive control of resonant power converters

Abstract

A power converter including a transformer, a resonant circuit including the transformer and a resonant capacitor having a characteristic resonant frequency and period, and output circuitry connected to the transformer for delivering a rectified output voltage to a load. Primary switches drive the resonant circuit, a switch controller operates the primary switches in a series of converter operating cycles which include power transfer intervals of adjustable duration during which a resonant current at the characteristic resonant frequency flows through a winding of the transformer. The operating cycles may also include energy recycling intervals of variable duration for charging and discharging capacitances within the converter. A gate driver includes a transformer, a plurality of switches, a current monitor, and a controller that operates the switches in a series of driver operating cycles having adjustable ON periods and adjustable transition periods during which capacitances are resonantly charged and discharged.