Non-dissipative battery cell balancing using half-bridge switching circuit

Abstract

Cells in an electric vehicle battery pack tend to become out of balance after several charging and discharging cycles, resulting in capacity under-utilization and over-sizing of battery packs to achieve extended driving range. This makes it necessary to have a cell balancing mechanism onboard of the battery management system. This paper introduces a half-bridge DC/DC switching circuit for the balancing of lithium-ion cells, and highlights its advantages over existing cell balancing techniques. Furthermore, details on planar transformer design, control feedback, simulation results in MATLAB/Simulink, and experimental observations are included, showing greater controllability and improvement in efficiency in comparison with existing systems.