Multifunctional On-Board Charger for Electric Vehicles with Low-Voltage Auxiliary Battery Charging

The on-board charger (OBC) of an electric vehicle (EV) is desired to perform many functions, such as transferring power from the grid to the vehicle (G2V), transferring power from the vehicle to the grid (V2G), and so on. To meet these requirements, a topology based on a four-switch three-port converter is proposed in this paper. In addition to the G2V and V2G functions, the proposed converter can transfer power from the high-voltage battery to the auxiliary low-voltage battery (H2L). Compared to the traditional OBC topology, the proposed circuit has a lower number of switches, reducing the cost of the system. Simulation results using PLECS software to demonstrate the effectiveness of the proposed topology.

I. Introduction

The market for electric vehicles (EVs) is booming [1], [2]. For customers, it is desired that the EV can be a power bank to supply home appliances in an emergency [3]. For the grid, the idle EVs are expected to be used as energy storage systems to balance power fluctuations on the power grid [4]. This requires the on-board charger (OBC) of EVs to be able to transfer power from vehicle to grid (V2G) [5], [6]. In an EV, in addition to the high-voltage battery used to power the drive train, a 12V auxiliary battery is included to provide power to the screen, indicators, speaker, sensors, etc. This low-voltage battery also needs to be charged from the grid (G2L). This charging energy can also come from the high-voltage battery (H2L) [7].