A high Step-down Converter with Low Voltage Stress on Power Switches and Leakage Inductance Energy Recovery

In this paper, a zero-voltage switching step-down converter is presented, which uses the technique of coupled inductor and series capacitor to reduce the voltage gain. Therefore, the voltage stress on the switches is reduced. The auxiliary circuit has the minimum number of elements, on the other hand, the auxiliary switch is also switched under ZV, and the reverse recovery problem of the freewheeling diode is also solved. The energy of the leakage inductor is discharged to the capacitor C and is properly transferred to the output. As a result, the capacitor C not only absorbs the energy of the leakage inductance, but also causes a further decrease in the voltage gain. Since the switches are operated complementary, it is easy to implement the control circuit. The simulation results show an increase in efficiency by 4% compared to the hard switching counterpart. Also, to confirm the correctness of the theoretical analyzes of the proposed high step-down converter, a 50 W practical prototype has been made.