Family of soft‐switching pulse‐width modulation converters using coupled passive snubber

Abstract

Efficiency, power density and electromagnetic interference (EMI) stand among the main concerns in power electronics and determine the quality of a power converter. To address the aforementioned concerns, this study proposes a cost effective passive soft-switching technique using coupled inductor for pulse-width modulation (PWM) converters. Through providing soft-switching conditions, switching losses are reduced and the use of coupled inductor technique improves the power density. Since, the slope of voltage and current variations over time is reduced by the proposed passive soft-switching technique, the EMI level is expected to reduce. This technique can be applied to a wide range of PWM converters, however, the analysis is focused on a soft-switching boost converter to provide a framework. The experimental measurements of the realised 200 W boost converter show that the efficiency is improved by 2 and 3.8% as compared to a hard switching boost converter with and without an RCD snubber circuit, respectively. Moreover, the experimental EMI measurements indicate that with no external EMI filter, the proposed technique has reduced the main peak of EMI level by 8 dBµV (in comparison to its hard switching counterpart) which satisfies CISPR22 class A EMC standard limitation.