Active Vehicle Battery Equalization Scheme in the Condition of Constant-Voltage/Current Charging and Discharging

This paper presents a battery-equalization circuit and its control strategy. Energy storage inductors are applied in the circuit and their number is less than that of the switches. The topology is simple and easy to control. The antiparallel diode of the power switches can provide freewheeling path of the inductance current, and the energy can be transferred by switching. Battery charging and discharging has constant-voltage and constant-current mode. The corresponding control strategies of the equalization circuit are different. The working principle is discussed and the control strategies in the conditions of constant-voltage and constant-current modes are analyzed. The simulation model of the active battery-equalization scheme and an equalization circuit combined with the battery management system are established. Also a comparison is made to the existing inductor-based equalization schemes. The simulation and experimental results verify the theoretical analysis. The proposed battery-equalization scheme can realize the expected effect.