전기 자동차 고효율 BMS 구현을 위한 하이브리드 타입 Charge Equalizer

Abstract

owadays, electric vehicle(EV) or hybrid electric vehicle(HEV) usually adopts a lithium-ion battery string, the charge imbalance of each battery makes many problems such as reduction of life cycle and explosion. Hence, the charge equalization circuit is required to guarantee life time and safety. In charge equalization circuit, the cost of a cell voltage sensing module is relatively high, but the equalization performance gets lower in case module is removed. For higher equalization performance without the cell voltage sensing module, an automatic chare equalizer based on switch-capacitor is proposed. One pre-charged capacitor with average voltage of batteries is implemented from a unidirectional DC-DC converter. The charge equalization can be automatically achieved by periodic connection between battery cell and capacitor charged average voltage without voltage sensing module. By using pre-charged capacitor in switch-capacitor converter, the faster equalization time can be obtained. This paper presents the operational principles and design consideration of the proposed equalizer.