Research on Two‐Stage On‐Board Charging System Based on Multiresonant Three‐Port Converter

ABSTRACT This paper focuses on the integration technology of on‐board charging system and on‐board DC/DC converter. A multiresonant three‐port AC/DC converter is designed and the topological structure, working principle and key features of the front‐stage and rear‐stage converters are analyzed. According to the design indicators, the configuration and optimization of parameters for critical components including inductors, capacitors, transformers, and switching transistors are completed. The fundamental harmonic approximation (FHA) is used to study the influence of relevant parameters on the voltage gain characteristics of the charging system. In view of the two‐stage cascading characteristics of the system, the modulation approach of PWM control is adopted in the front stage and PFM control in the rear stage, and the relevant parameter design is completed through small‐signal modeling. The inverter circuit is integrated with the charging circuits on the high‐ and low‐voltage sides by using a three‐port transformer, replacing the traditional split structure with an integrated structure, which can charge both high‐voltage power batteries and low‐voltage storage batteries simultaneously. The high‐voltage side charging circuit can achieve bidirectional energy flow, and its forward and reverse operation characteristics are consistent, greatly simplifying the control difficulty. This multiresonant topology achieves concurrent delivery of fundamental and third harmonic spectral components, achieving the required voltage gain within a certain range of AC input frequency variation. Based on theoretical analysis and characteristic research, an experimental prototype with a 400‐V high‐voltage output and a 13.8‐V low‐voltage output was trial‐produced. The results of the experiment demonstrate that the system can achieve bidirectional energy flow, meet the requirements of wide gain and high‐efficiency operation, and verify the correctness of the design.