Abstract:

The vehicle power battery pack is prone to deterioration in consistency during charge and discharge cycles, which may cause battery capacity attenuation and even cause security problems. In this paper, a multi-equalizer composite equalization system based on CAN communication was proposed. The system could cascade multiple equalizer, and each equalizer included an active equalization part which used the charge chip to charge low power cell. The passive equalization part which composed of resistor arrays was used to discharge high power cell. In addition, each equalizer was equipped with a high-power resistance for battery module overall fast discharge. In order to achieve the purpose of composite equalization, effective control strategy and equalization algorithm were designed. The simulation and physical experiments were set up to validate control strategy and equalization algorithm. In the physical experiment, the voltage range of the battery pack was reduced from 200 mV before equalization to 20 mV after equalization, indicating that the consistency of the battery pack was obviously improved with the equalization system.

Key words: lithium-ion battery pack, inconsistency, active equalization, composite equalization, equalization control strategy, Multi-module