Evaluation of bi-directional single-inductor multi-input battery system with state-of-charge balancing control

This study presents a bi-directional single-inductor multi-input single-output battery system with state-of-charge (SOC) balancing controller. In the discharging operation mode of the battery system, the SOC balancing between multiple batteries is achieved by adaptively modulating the multipliers of the discharging rate of each battery cell, while maintaining the output voltage regulated at the desired value by modulating the average value of duty cycle of the power converter. The SOC balancing is achieved naturally during the operation of the system without extra energy dissipation or charge transfer between the batteries. In the charging operation mode, each battery can be charged independently by using the same bi-directional power stage. The convergence ability of the SOC balancing controller is discussed and results obtained from a proof of concept experimental prototype are presented and discussed in order to evaluate and validate the operation of the controller and system.