Cell balancing control using adjusted filters in flyback converter with single switch

Cell balancing method using multi-winding flyback converter is simple and easy to control, but it has unequal secondary voltages due to the non-uniform turn-ratios of secondary windings and the leakage inductance difference caused by multi-winding. Especially it is difficult to control multi-winding effect by using turn-ratio, because secondary-side has little number of turns. This paper proposes the control method eliminating the multi-winding effect without any additional switch in multi-winding cell balancing method. The individual cell control by making their frequency characteristic differently using single flyback converter and adjusted filter is proposed. Simulation and experimental results proved that each cell is equally balanced using adjusted filter and frequency selection.