Balance Method of Lithium-Ion Battery Pack Based on Multi-Secondary Coaxial-Winding Transformer

Due to the inconsistency of the lithium-ion battery pack, the active balance method based on multi-secondary coaxial-winding transformer was introduced. The control principle of the balance system was analyzed, and the energy transfer process was explained. A balance system model was established by using MATLAB/Simulink, including battery model, transformer model and SOC calculate model. The duty cycle and the frequency of the MOSFET in the primary and second side of the transformer were studied to work out the balance system control strategy. According to the simulation results, multi-secondary coaxial-winding transformer can be used to balance the batteries’ voltages, and the energy losses can be reduced by choosing high-frequency transformer.