GaN Power Converter with low inductive hybrid PCB Technology

Abstract:
The wide-bandgap semiconductor material gallium nitride offers improved electrical properties compared to silicon, which can increase the performance and efficiency of converters in power electronics. The simulation programs Ansys Icepak, Ansys Q3D Extractor and LTspice were used to investigate the thermal and electrical switching behaviour of a half-bridge board with 650V discrete gallium nitride semiconductors. To investigate the electrical and thermal performance of the GaN half-bridge board based on a single-layer metal substrate PCB, it is combined with a multilayer PCB to form a low inductive hybrid circuit board structure. The resulting converter applies a DC-link capacitor in which the turn-off overvoltage is suppressed by a laterally guided commutation loop on the half-bridge board. At 500VDC input voltage and switching times of less than 10 ns, a maximum voltage of circa 550V occurs across the GaN transistors. Operated at up to 144 kHz switching frequency and 50% duty cycle in buck mode, the setup reaches its peak efficiency of 99.4% at 2kW output power. At the maximum tested operating point of 5.9 kW, the efficiency of the converter in buck mode is 98.5 %.