A Soft-Switching Three-Phase Inverter Based on Integrated Magnetic Coupled Active Filter

In this article, a soft-switching three-phase inverter based on an integrated magnetic coupled active filter (MCAF) is presented, which offers soft switching operation for the power switches and low output current ripple. The proposed MCAF actively applies the switching voltage on the coupled auxiliary inductors, which generates the mutual-inductance voltage to offset the switching voltage on the grid-side inductor, thus reducing the switching current ripple on the output branch at any switching frequency. The switching frequency insensitivity characteristic of MCAF makes it ideal for variable frequency operation, which can provide the full range soft-switching conditions. The proposed integrated MCAF reuses the switches of the inverter itself, and requires only a single three-phase symmetrical magnetic core and three capacitors, which makes it small in size. Furthermore, the mapping between ripple cancellation condition and magnetic core structure parameters is obtained based on the magnetic circuit analysis, which makes it more feasible in industrial applications. Finally, a laboratory prototype with a rated power of 2KW is constructed to validate the effectiveness of the proposed inverter.