Zero voltage switching non-isolated bidirectional DC-DC converter with transient current built-up technique

Non-isolated bidirectional dc-dc converters (NBDCs) are widely used in energy storage systems. However, the zero-voltage switching (ZVS) for NBDCs is hard to realize by adding auxiliary circuits. The auxiliary current should be larger than the filtering inductor current. Then the auxiliary current causes high conduction losses, which have adverse effects on efficiency. In this paper, a ZVS NBDC with a transient current built-up technique is proposed, where the transient current is built in a very short time by an auxiliary circuit. The average value of the auxiliary current is quite small, which results in low conduction loss. The proposed auxiliary circuit does not result in high current or voltage stresses and does not affect the filtering inductor current. Experimental results show the correctness of the proposed zero-voltage switching method. They also show that the efficiency of the proposed NBDC is higher than that of the hard switching NBDC.