High Performance GaN Inverter for High-Speed Application

Hydrogen is a promising high-density energy carrier for future transportation applications. For its usage in fuel cells, high-speed compressor systems are required for the air-supply with resulting electric motor speeds often exceeding 100.000 rpm. The following paper presents the design of a novel 80 kW high-speed drive system consisting of a permanent magnet synchronous motor (PMSM) and a corresponding wide-bandgap based inverter system. The high electric rotation frequency in combination with the low-inductance machine design leads to the necessity of high inverter switching frequencies and output currents with low harmonic distortions. Multilevel topologies help to reduce switching loss for such applications and enable the use of highly efficient 650 V GaN devices in 800 V inverter systems. In addition, these topologies can lead to improved current quality. A simulative study of the resulting inverter and motor behavior and efficiencies is presented and compared to standard B6 inverters.