Simplified control for redistributive balancing systems using bidirectional flyback converters

Battery stacks with many cells per string require sophisticated balancing hardware for capacity maximization, safe operation, and extended lifetime. This paper proposes a simplified control architecture for redistributive battery balancing topologies. A high level controller defines the link currents to be actuated by flyback DC/DC converters. Linear transformations are used to rewrite the balancing problem as a regulation problem that can be solved with a saturated LQR. To reduce the overall system complexity and cost, the low-level control requirements are minimized using feedforward approaches based on pulse width and pulse frequency modulation. The control system is developed using MATLAB/Simulink/PLECS and validated experimentally.