A Parallel Resonant DC Link Soft Switching Inverter With Simple Structure and Its Modulation Strategy Analysis

Aiming at the problems of high current stress, large conduction loss, and overly many components in the auxiliary commutated circuit (ACC) of the newly proposed parallel resonant dc link inverter (PRDCLI), this article proposes a modulation strategy. It includes two parts: a strategy for minimizing the ACC operating frequency and a synchronize strategy using shunt dead zone. With this new modulation strategy, the original PRDCLI is simplified to the PRDCLI with a simple structure. Compared with the original modulation strategy and PRDCLI, the proposed modulation strategy and PRDCLI can: 1) guarantee soft-switching of all switches; 2) minimize ACC operating frequency to reduce conduction loss; 3) separate load current and resonant current during ACC operation to reduce current stress; and 4) delete a group of resonant circuits to reduce hardware cost. In this article, the operation principle under the proposed modulation strategy and PRDCLI is described in detail. Its characteristics are analyzed, which include voltage/current stress, components number, and parameter design. Experimentally, a general prototype (SiC MOSFET, 8 kW/80 kHz) is used to compare the original modulation strategy and PRDCLI as to verify the efficacy of the proposed ones.