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 400 V battery pack and 2 kW 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. These two aspects make the proposed topology a novel approach in this industry. The proposed MPC can provide up to 5 kW, while benefiting from two additional paths to the freezer unit during idling and/or fault modes. The proposed MPC is compared to seven multi-port converters from literature to demonstrate its benefits compared to its counterparts. Also, the proposed topology is compared to a multiple converter counterpart with only SISO converters. The comparison shows 71% fewer MOSFETs, 33% fewer diodes, and 7.6% fewer passive components. 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.