2 kW Dual-Output Isolated DC/DC Converter Based on Current Doubler and Step-Down Chopper

In the context of the auxiliary power for motor-driven vehicles having two systems, we propose a new topology for a dual-output isolated DC/DC converter, which offers advantages in terms of efficiency and size. The proposed circuit consists of an H-bridge inverter, a transformer, and an integrated circuit of a current doubler and step-down chopper. Considering the high power and high frequency, our objective was to evaluate and identify the issues of an actual device with a power output of 2 kW and switching frequency of 400 kHz. The circuit feasibility was examined through measurements of the prototype, and both the voltage target response and load disturbance response characteristics were confirmed to operate as designed. The maximum and minimum efficiencies of this circuit were 81.3 and 61.5%, respectively, demonstrating that the load loss of the step-down chopper had a significant impact on the efficiency. The loss analysis revealed that the loss at the integrated circuit on the secondary side accounted for more than 50% of the total loss. Moreover, issues such as the behavior at power-on, efficiency, and size were identified and evaluated, thereby achieving the objectives of the study.