A High-Performance Grid-Tied Three-Level T-Type Converter for Off-Board Battery Chargers under AC-Side Voltage Distortions and Unbalances

Abstract

The conversions are a key factor in the battery charging of electric vehicles. The off-board battery chargers, which are composed of converters and controller units, are needed to fast charge by transferring high-power. The converters should serve applications even with unusual grid systems where non-sinusoidal grid currents occur. This paper describes a high-performance, three-level T-type converter for off-board battery chargers. It can operate under conditions of grid voltage distortions and grid voltage unbalances. The proposed control algorithm provides the three-phase sinusoidal currents to prevent their effect on the grid system and the equipment, which is an improvement from the conventional control algorithm. The constant current and constant voltage modes are applied for charging applications. Moreover, the power factor correction can be obtained. The simulation results are provided to investigate the performance of the off-board battery charger based on the three-level T-type converter.