7.2 kW Multifunctional and Integrated On-board Electric Vehicle Charger

A Two stage on-board electric vehicle charger (OBEVC) has a front-end power factor correction (PFC) converter and a dc-dc converter to charge the main battery. In addition, there is an isolated dc-dc converter, typically one-third the rating of the main battery charger, to supply various auxiliary low voltage loads. In this paper, a new on-board charger consisting of fewer circuit components and having a higher power density compared to the converters reported in the literature, is proposed. This is achieved by completely eliminating the isolated low power dc-dc converter. In grid connected mode, Totempole PFC and dual active bridge (DAB) perform either grid to vehicle (G2V) or vehicle to grid (V2G) operation with main battery. In driving mode, an interleaved buck converter is formed using the first stage circuit (Totempole) components. The second leg of Totempole PFC is integrated with ripple power compensation (RPC) circuit to eliminate the second order ripple power in the dc link. It also serves as one of the phases for interleaved buck converter in driving mode. The DAB along with interleaved buck converter supply power to the auxiliary battery and low voltage loads. The operation of this converter is explained and detailed simulation studies on a 7.2 kW on-board charger are carried out.

I. Introduction

Conventional two stage OBEVC consists of a PFC stage and a dc-dc converter stage to charge the main battery (MB). Apart from electric propulsion, there are many electronic loads in the vehicle which are fed at 12/24V. To serve these loads, an auxiliary battery (AB) is used. This AB is charged when the vehicle is in drive mode. An isolated dc-dc converter is used as a power electronic interface between MB and AB. In medium range electric vehicle (EV) the rating of this converter varies between 2.4 kW to 3 kW. When OBEVC is charging the main battery (known as grid connected mode), the converter feeding the other electronic loads is idle, and while the vehicle is moving (in drive mode) the OBEVC is idle. Various attempts have been made to develop integrated topologies with fewer circuit components there by reducing the cost and improve the power density [1]- [6].