Compact GaN-Based 25kW, 480V Three-Level Active Front End Rectifier

Interface units are needed to connect DC microgrids to the AC grid. This paper presents a compact and high-efficiency 25kW 480V Gallium Nitride (GaN) based bidirectional Three-Level Active-Neutral-Point-Clamped (3L-ANPC) converter for DC microgrids. The entire system, including the FPGA, DC-link capacitors, switching devices in the topology, and AC grid inductive filters, is integrated onto a single board. The 3L-ANPC topology provides balanced distribution of power losses and voltage stress among the switches. A 200kHz switching frequency is used for the GaN devices to reduce the size of passive elements. A PCB-based DC busbar is designed to minimize inductance, ensure a compact size, and reduce parasitic capacitances. Additionally, PCB-based inductors are designed to minimize size and tolerance on inductance value and reduce magnetic flux pollution in the converter. System control is performed using an Intel ultra-high-speed FPGA. Simulation and experimental results validate the electrical and thermal performance of the proposed design.