A Transformerless Soft-Switching Multiport Integrated Converter with Leakage Current Suppression for Residential Energy Management

This article describes a complete transformerless soft-switching integrated multiport converter (SSIMPC) without leakage current to integrate residential photovoltaic (PV), energy storage, dc bus, and ac grid ports. The PV port can operate in continuous current mode (CCM) to control renewable energy utilization and achieve low input current ripple. The energy storage port acts as an energy buffer and also provides soft switching with flexible control. As distinct from previous work, the multiport converter described in this article can realize soft-switching with leakage current suppression. Because of an indirect duty ratio decoupling modulation strategy, multiplexed zero-voltage switching (ZVS) devices and inductors can be realized without extra passive components. The common-ground structure helps with safety and suppresses leakage currents. With multiple ports, the local controller can be used for energy management to realize multiple power combinations of renewable energy, energy storage, and grid flow, with emphasis here on comprehensive residential applications. The common-ground integrated multiport soft-switching structure not only suppresses leakage current but also exhibits good efficiency performance. A 1-kW prototype verifies the correctness of the theoretical analysis and the feasibility of topology.