GaN FET 기반 플라이백 컨버터를 이용한 능동 셀 밸런싱의 성능 향상

Abstract

In a battery module with multiple cells in series, the efficiency of the cell balancing circuit is very important because it is related to the balancing time and energy usage. This paper proposes a high efficiency active cell balancing circuit that can transfer energy from module to cell. The proposed balancing circuit consists of a flyback converter for transferring energy and bidirectional switches for selecting a weak cell. In order for the proposed circuit to have high efficiency, the flyback converter uses GaN FETs with excellent electrical characteristics and operates in DCM(Discontinuous Conduction Mode) for soft switching. To verify the performance of the proposed circuit, a 5W GaN FET based flyback converter was built and cell balancing experiments was performed. This was compared to a MOSFET based balancing circuit. Experimental results show that the proposed circuit improves maximum efficiency by 8.6%, reduces cell balancing time by 10%, and reduces cell balancing energy loss by 16% compared to the MOSFET-based circuit.