Equalization of EV and HEV batteries with a ramp converter

Valve-regulated Pb-acid (VRLA) batteries used on electric vehicles (EVs) and hybrid electric vehicles (HEVs) are subject to voltage imbalances which greatly diminish battery lifetime and vehicle range. This paper describes an equalizer that is implemented with a high frequency, soft-switching power converter that corrects this imbalance. Experimental results are presented for a pack of 27 batteries.