Design and Validation of a Passive Balancer Based on Switched Shunt Resistor for Medium Power Ratings in Electrification Transportation

This article presents the implementation of a passive balancing strategy in an energy storage network based on LiPo cells. The proposed system is intended to operate in a 5.6 kWh battery pack for two-wheeled electric vehicle applications. The battery balancer allows voltage equalization between the LiPo cells before and after the charging process, ensuring controlled charging cycle for each cell. The LiPo cell balancer uses a passive method which transforms the excess of electric energy into heat by means of a resistance described in the Joule Effect. In order to minimize energy losses, three operating modes were proposed: post-charge, pre-charge, and storage node balancing. The post-charge mode reduces the cell voltage to 4.20 V, while the voltage is set to 2.8 V in the pre-charge mode. The design and construction details of a six-cell module prototype are described in this paper, along with experimental research. The balancer system was successfully operated in the series modules of the LiPo battery pack using the proposed modes of operation.