DC-DC converter with a wide range of providing a natural switching mode at ZVS mode

Abstract

This paper introduced an isolated soft switching DC-DC converter with an active rectifier. The converter has two bidirectional and two reverse conducting devices at the inverter side and utilizes phase-shift control with one variable and constant switching frequency. Instead of relying on the magnetizing or circulating current, the soft-switching operation of the proposed converter using novel modulation method is provided by relatively short additional switching state, which minimizes the energy circulation. This interval is introduced by taking advantage of the reverse blocking capability of the devices in the rectifier side and ensures the recharge of snubber capacitance at the inverter side. The soft switching operation of the converter is load-independent and does not require introduction of multi-mode control strategies. Thanks to the novel modulation algorithm, the converter features ZVS and ZCS over a wide operating range, even at no-load condition. The solution is aimed to reduce the problem of high circulating energy in the existing PWM topologies at light load. For the proposed solution, the amount of circulating energy is load adaptive, which results in good weighted performance over a range of possible operating points. Operation and design aspects of the converter were presented and verified experimentally.