A Bipolar-Assisted Regulation Quasi-Single-Stage DC-DC Converter for a Wide Input Voltage Range

The quasi-single-stage dc/dc converter employs an auxiliary converter to regulate the output voltage, enabling better adaptation to a wide input voltage range. However, conventional quasi-single-stage dc/dc converters exhibit significant power flow through the auxiliary converter under rated input voltage condition, limiting efficiency improvements and causing distortion in the resonant current. To address these issues, this article proposes a novel bipolar-assisted regulation quasi-single-stage dc/dc converter. First, the fundamental characteristics of the proposed converter, such as its operating mode, gain regulation, and power distribution, are analyzed. Second, a parameter design method is introduced to achieve zero voltage switching turn on for power switches. Building on this, a closed-loop control strategy is proposed to regulate the output voltage. Finally, the main circuit parameters derived from the optimized design are utilized, and an experimental prototype is developed and demonstrated to verify the effectiveness and advantages of the proposed converter, achieving an efficiency of 97.9% at rated input voltage and power.