An Auxiliary H-Bridge-Based Bipolar-Assisted Regulation Quasi-Single-Stage DC/DC Converter

The quasi-single-stage dc/dc converter adjusts the output voltage through an auxiliary converter, better adapting to the needs of data center power supply units. However, existing quasi-single-stage dc/dc converters operate with high power flow through the auxiliary converter at rated input voltage, restricting efficiency improvement. To address these issues, this article proposes a novel quasi-single-stage dc/dc converter that achieves voltage regulation of the main converter via a bipolar auxiliary port, thereby reducing power flow through the auxiliary converter and improving efficiency at the rated input voltage. First, the basic characteristics of the proposed converter are analyzed, including working mode, gain adjustment, and power distribution characteristics. Second, a parameter design method is proposed to achieve ZVS turn on in all power switches. Based on this, a closed-loop control strategy for output voltage is proposed. Finally, based on the main circuit parameters obtained from the optimized design, a 320–450V input and 12V/500W output prototype is demonstrated, achieving a peak efficiency of 96.76%.