Optimal control of bidirectional active clamp forward converter with synchronous rectifier based cell-to-external-storage active balancing system

Abstract Active cell balancing is a more energy-efficient way of balancing cells in series comparing to passive balancing. To further improve the performance of an active balancing system, an optimal control approach can be applied to optimise the system performance indexes. This paper proposes an optimal controller for the bidirectional active clamp forward converter with synchronous rectifier (ACFC-SR) based cell-to-external-storage active balancing system to concurrently optimise the balancing speed and the energy efficiency. The formulated optimization problem does not require the complicated nonlinear converter efficiency model compared to other optimal controllers that involve efficiency model to reduce energy loss. The flexibility in changing the balancing priority of the balancing time and the converter efficiency is achieved via different weights on the objective function. The effectiveness of the proposed controller is validated experimentally with real cells and the power electronics board.