Parallel Capacitive-Link Universal Converters with Low Current Stress and High Efficiency

Series capacitive-link universal converters are a relatively new class of single-stage power converters that offer numerous advantages including high reliability, high power density, and high efficiency. One of the limitations of these converters is high current stress of the switches, which lowers their efficiency in high current applications. In this paper, a new class of soft-/hard-switched parallel capacitive-link converters is introduced to address this limitation of the series capacitive-link universal converter while keeping its advantages. A small film capacitor, which is placed in parallel with the input and output switch bridges, is responsible for transferring the power from input towards output. A small inductor can be placed in series with the link capacitor to minimize switching losses and reduce EMI. The proposed parallel capacitive-link converter is expected to offer an enhanced efficiency and reduced current stress compared to the series capacitive-link universal converters. In this paper, principles of the operation of the proposed converter will be presented and its performance and advantages will be verified by simulation.