High Frequency Link Isolated Multi-Port Converter for Active Cell Balancing Applications

This paper proposes an isolated multi-port converter based on high-frequency AC link to combine the multiple modular cell-level active balancing converters into a multi-port converter. The topology uses integrated magnetics and just one central secondary bridge, which reduces significantly the number of switching devices and passive components required for the implementation of the battery management system. Additional advantages include use of the same ground reference for all the cells, eliminating the need for isolated communications between active balancing converters. Steady-state analysis for the topology is given. A simple control scheme is proposed for the differential currents required for active cell balancing. Closed-loop simulation results are provided for a three-cell system that validates the proposed control scheme for the topology. A 100 W 4-port prototype converter is developed and experimental results are given to prove the feasibility of the proposed high-frequency link coupled multi-port converter.