Selective flyback balancing circuit with improved balancing speed for series connected Lithium-ion batteries

In this paper, a cell balancing circuit for the Lithium-ion battery string based on the Flyback topology is proposed. The proposed circuit draws the charge out of the high voltage cell and recovers it to the overall battery pack. With the selectivity of the target cell, the proposed circuit uses the minimized power path to simplify the circuit and optimize the balancing efficiency. The circuit also employs the peak current mode control scheme to accelerate the balancing speed and reduce the balancing time. Experimental results with the laboratory prototype hardware for multi-cell battery string verify the feasibility of the proposed scheme.