Bidirectional DC-DC converter with high step-down and step-up voltage conversion ratio

Abstract

A bidirectional DC-DC converter with high step-down and step-up voltage conversion ratio is proposed in this paper. Two capacitors series in the high-voltage side of proposed converter are used for voltage division. The divided voltages are then discharged to and charged from the low-voltage side by a modified two-phase interleaved buck-boost converter, respectively. Due to stacking architecture of the proposed converter, high bidirectional voltage conversion ratio with low voltage stresses on power switches can be achieved by the proposed converter with reasonable duty ratio. Besides, a smart phase-rotating control scheme can be integrated into the proposed converter to improve the conversion efficiency at light loads. A prototype circuit with a voltage of 200V in high-voltage side, a voltage of 24V in low-voltage side and a rated output power of 500W is implemented to verify the performance of proposed bidirectional DC-DC converter. Experimental results show that the maximum conversion efficiencies, about 93.40% and 93.86%, for step-down mode and step-up mode, respectively along with lower voltage stresses on power switches can be achieved. Besides, a conversion efficiency improvement of 5.42% can be accomplished for the proposed converter with smart phase-rotating control scheme under 25W.