Dual Active Bridge Converter with AC Heating Capability for Lithium-ion Batteries in Electric Vehicles

Abstract

Lithium-ion batteries in electric vehicles need to be adequately heated at low temperatures to avoid the decrease in discharge capacity. AC heating techniques utilizing Joule heat generated by the internal resistance of batteries have been proposed. Although these techniques achieve higher heating efficiency and uniform heating, an ac heating inverter is separately necessary to produce the ac current, likely resulting in increased system complexity and cost. This paper proposes a dual active bridge (DAB) converter integrating an inverter for ac heating in electric vehicles. The proposed converter is derived by sharing two legs of both converters, achieving the simplified system and low-cost. Experimental results of a prototype with a charge-discharge power rating of 300 W demonstrated that in addition to the bidirectional power flow, the proposed converter heated up the twelve-cell battery from −11℃ to 0℃ within 10 min.