Leakage current mitigation of non-isolated integrated chargers for electric vehicles

Abstract

Integrated chargers have the potential to reutilize the existing on-board, high power-rated electronic components for charging purposes to save costs. However, while electric vehicle (EV) chargers are traditionally isolated from the grid, the integration of isolation is impractical with the conventional power train. Large leakage current exists in non-isolated integrated chargers due to the lack of galvanic isolation and the coupling between the ac and dc side common mode (CM) filters. With realistic system parameters, such leakage current brings safety risks to both the end-users and the on-board electronics. The feasibility of various possible mitigation techniques are discussed and aided by simulation results. The analysis of one of the potential solutions, floating filters, are discussed in detail. With a baseline charger test setup, experimental results are presented to show the leakage currents at different switching frequencies, and the effectiveness of the improved filter topology.