Resonant switched-mode DC-DC converters

Abstract

Soft-switching (resonant) switched-mode DC-DC converters can have potential advantages, such as lower overshoot, switching and conduction losses, and electromagnetic interference, compared to their standard hard-switching counterparts. This report reviews and investigates two types of resonant-based switched-mode DC-DC converters: Zero Current Switching (ZCS) and Zero Voltage Switching (ZVS). The operation principle of ZCS is zero current during the turn-off transition. The operation principle of ZVS is zero voltage during the turn-on transition. Generally, ZVS is more advantageous than ZCS due to the ability to eliminate overvoltage, switching loss, and electromagnetic interference. In this report, we investigate ZVS for low-power applications.

ZVS Square-Wave Resonant Switch is selected as it features low switching loss. The proposed model used is a modified version of bulk converter with synchronous rectifier. Synchronous rectifier behaves as such that the currents are reversed when it is connected to MOSFETs. MOSFET’s R_on must be very small, so that the conduction loss is minimized.

The function of buck converter is to obtain a regulated output voltage, V_out which could be a different magnitude from〖 V〗_in. In this report, it shows that by inserting a low input voltage, the simulation results obtained is equivalent to the calculated output results. On the basis of this observation, it is recommended that ZVS Square-Wave Resonant Switch can be used if designer objective to achieve low power. The expressions used are verified by computer simulations.