Zero-voltage-transition control for a class of resonant converters

The aim of this letter is to improve operation of a class of resonant converters and take quasi-resonant converters (QRCs) as a benchmark to realize this aim. In particular, a variable pulsewidth control scheme is proposed that ensures soft-switching conditions and reduces conduction losses. The control scheme has the feature of significant improvement of efficiency and wider voltage conversion ratio. The proposed controller modifies the pulsewidth of the square driving signal without modifying its frequency. This fact makes it able to be used as a complementary control action to voltage regulators. Results are illustrated via experimental work for the case of a boost-type zero-voltage-switching QRC.