An Isolated Step-Down Multi-Port DC-DC Power Converter for Electric Refrigerated Vehicles Auxiliary Power Unit System

This paper proposes an isolated step-down DC-DC multi-port converter (MPC) for the auxiliary power unit of refrigerated vehicles. Mercedes-Benz eSprinter is used as the baseline for this design with 400V battery pack and 2kW of auxiliary loads. TR-300T refrigeration unit from GUCHEN THERMO is chosen to provide temperatures as low as -18 degrees Celsius for the van's 12 cubic meter cargo space. Similar to Mercedes-Benz Sprinter model, two auxiliary battery units are used to design this MPC. The proposed MPC can provide up to 5kW, while benefiting from two additional paths to the freezer unit during idling and/or fault modes. The proposed MPC has 35% fewer active components compared to the state of the art, while offering higher reliability for the overall system. Simulation and experimental results demonstrate the effectiveness of the proposed MPC, and the control system designed for this application and efficiencies up to 95% were recorded.