A Soft Switching Scheme for Multiphase DC/Pulsating-DC Converter for Three-Phase High-Frequency-Link Pulsewidth Modulation (PWM) Inverter

This paper outlines a switching scheme to improve the energy efficiency for an isolated high-frequency multiphase dc/pulsating-dc converter, which is the front end of a three-phase rectifier-type high-frequency-link inverter. Without using any auxiliary circuit, the proposed switching scheme achieves zero-current or zero-voltage switching for the power switches on the front-end multiphase dc/pulsating-dc converter. Moreover, on the back-end pulsating-dc/ac converter, the proposed soft-switching scheme reduces the switching frequency requirements for the associated switchers, which need high-frequency switching. In conjunction with the back-end pulsating-dc/ac converter, operating with a patent-filed hybrid modulation scheme, the proposed switching scheme leads to reduced overall switching loss as compared with other existing schemes. It is more suitable for isolated low-voltage dc to three-phase high-voltage ac applications from the standpoints of cost, efficiency, and footprint.