Current Shuttling Cell Voltage Balancers: Design, Evaluation, and Simulation

Abstract

Batteries are becoming increasingly important in a variety of applications, including electric vehicles and ships as well as load matching in electric grids. Cell voltage balancers are critical to extracting maximal performance out of batteries and to extending their lifespan. Charge pump balancers can quickly and efficiently shuttle charge across battery cells to equalize voltages. Component selection of MOSFETs and capacitors is vital in optimizing for performance, cost, and volume. This thesis presents experimental and PSpice simulation data from several capacitor-based charge pump configurations designed for cell voltage balancing. At 0.4 V cell differential, the peak balance current of the 2S balancer was over 9.9 A. At 0.8 V cell differential, the peak balance current of the 4S balancer was over 14.6 A. Ultimately, these charge pumps can be combined to construct a high-current and multilevel cell voltage balancer efficient across a wide range of voltages.