A ZCS-PWM Voltage-Driven Three-Level Converter With a Secondary-Side Simple Soft-Switching Snubber

A very simple, low component count snubber is used in order to get ZCS for all the switches of a three-level voltage step-down converter. ZCS allows for the implementation of the switches with insulated-gate bipolar transistor which are able to withstand large input voltages at large power. The snubber is placed in the secondary-side, before the rectifier. The transformer leakage inductance is used in the ZCS-purposed resonant process, eliminating thus the need for an additional resonant inductor. All the resonant circuit energy is recuperated to the load. No voltage stresses appear on the switches, and the current stress is limited in a tradeoff components design. The proposed solution allows for a boost of the effective duty cycle. As a result, the proposed converter operates with a high efficiency.