Efficient and Bidirectional Cascaded Auxiliary Power Module Design for Electric Trucks Using Hybrid Si, SiC, and GaN Technologies

In battery electric vehicles (BEVs), ensuring reliable auxiliary power is crucial for supporting essential functions such as communications, cooling systems, cabin air conditioning and emergency braking. Traditionally, 12V batteries have been widely used for auxiliary systems, but there is now a shift towards 48V systems, driven by the need for improved vehicle efficiency and enhanced performance. This transition is significant, especially for future medium and heavy duty BEVs, which are expected to use multiple low-voltage (LV) batteries to optimize power distribution. As part of an EU H2020 project, it is required to develop a digital twin model of the auxiliary loads power supply for an electric Truck. Hence, this research focuses on providing a proof of concept validation for an isolated DC-DC converter, known as the auxiliary power module (APM) through a high-fidelity model. This paper presents the design and evaluation of a single-input, multi-output cascaded APM topology for electric trucks, emphasizing its efficiency and performance. The integration of advanced switching technologies, including Si and SiC MOSFETs and GaN HEMTs, is highlighted for their potential to enhance APM functionality. A high-fidelity co-simulation model has been developed using PLECS-Blockset and MATLAB Simulink, demonstrating the APM's ability to achieve a peak efficiency of 98% at 10 kW in bidirectional power control between the high voltage (HV) bus and two LV buses.