High-Efficiency, High-Fundamental Frequency Inverter for High-Speed Electrical Drive in a Micro Gas Turbine-Based Vehicle Powertrain

This paper presents the design, analysis, and validation of a high-efficiency inverter for high-speed electric drives in micro gas turbine (MGT)-based vehicle powertrains. A 30 kW, 700 VDC, two-level, three-phase voltage source inverter (VSI) using silicon carbide (SiC) MOSFETs is developed to operate at a 2 kHz fundamental and 40 kHz switching frequency. Unlike conventional inverters operating at 50–60 Hz, this design supports high-speed motors (above 100,000 rpm) by increasing the fundamental frequency to 2 kHz. A detailed comparison between two-level and three-level T-type topologies is conducted, with the selected topology maintaining over 99% efficiency across a wide frequency range. The design incorporates detailed loss modelling, a low-inductance PCB layout, and optimized DC-link capacitor selection to ensure robust high-frequency operation. The influence of modulation index and switching frequency ratio on inverter efficiency and current total harmonic distortion (THD) is analyzed, highlighting their impact on thermal performance and current quality. Thermal simulations using PLECS estimate a peak efficiency of 99.3%. The design is validated through simulation and experimental testing on a 30 kW prototype, achieving 14.3 kW/L power density and 25 kW/kg gravimetric density. Comparative analysis with recent literature confirms the proposed inverter’s advantages in power density, efficiency, and high-frequency capability.