Half-Bridge Full-Bridge AC-DC Resonant Converter for Bi-Directional EV Charger

Abstract

A new topology and controller based on single-stage AC-DC resonant converter, without Electrolytic capacitors (E-cap), for bi-directional EV battery chargers is proposed in this paper. The topology is a Half-Bridge (HB)-Full-Bridge (FB) resonant converter with MOSFET's connected in series and in opposite direction on its AC Half-Bridge side plus an active filter on the DC-side. No use of E-cap makes the converter more reliable. The establishment of an appropriate control scheme enables a wide range of active and reactive power control under different AC and DC voltage levels. The proposed controller not only facilitates the converter to operate under Zero Voltage Switching (ZVS) for all switching instants, but also it minimizes the conduction loss. ZVS allows higher switching frequencies and together with reduction in conduction losses improves the efficiency. The active filter is controlled to absorb the low frequency current ripple and prevent it from going to battery. Charging the battery with reduced low frequency ripple prevents extra heat production and increases the lifespan of the battery. Mathematical analysis, simulation and experimental results are presented.