Design considerations and loss analysis of zero-voltage switching boost converter

A novel zero-voltage switching (ZVS) boost converter for medium- and high-power applications is proposed. Compared to conventional hard switching boost converters, the switching losses are decreased by a factor of 3 to 4. A design procedure is proposed, based on the minimisation of the total losses in the switch. It is shown that variations of operating frequency, turn-off current and voltage rise time do not affect the control algorithm or the design procedure, even for a wide range of loading conditions and input voltage. A 3kW prototype using IGBTs is simulated (PSPICE) and developed. The efficiency obtained is more than 90% for load values higher than 20% of full load, and attains 95% for full load. Advantages of the circuit include zero-voltage-zero-current turn-on and zero-voltage turn-off for a wide range of line voltage and load; switching conditions do not depend on the load. The reliable control strategy makes the proposed ZVS boost converter attractive for medium-power applications where IGBTs are used predominantly.