Three-Phase Sinusoidal Output Buck-Boost GaN Y-Inverter for Advanced Variable Speed AC Drives

• Published in: IEEE journal of emerging and selected topics in power electronics Vol. 10; no. 3; pp. 3459 - 3476
• Main Authors: Antivachis, Michael, Kleynhans, Nicolas, Kolar, Johann W.
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: A C motors; AC motors; Battery; control system; drive system; Electric converters; Electric potential; Energy conversion; Fuel cells; fuel-cell; Hardware; high-speed; inverter; Inverters; Modules; Motor drives; Prototypes; Sine waves; Stress; Topology; Variable speed drives; Voltage; Waveforms
• ISSN: 2168-6777; 2168-6785
• DOI: 10.1109/JESTPE.2020.3026742

Motor drive systems supplied by a fuel-cell/battery are especially demanding when it comes to the design of the inverter. Besides a high performance (high efficiency <inline-formula> <tex-math notation="LaTeX">{\eta } </tex-math></inline-formula> and power density <inline-formula> <tex-math notation="LaTeX">{\rho } </tex-math></inline-formula>), the inverter has to cope with the wide dc voltage variation of the fuel-cell/battery that supplies the motor drive. A promising three-phase inverter topology, denoted as Y-voltage source inverter (VSI), is presented in this article. The Y-VSI is a modular three-phase inverter and comprises three identical phase-modules connected to a common star "Y" point. Each phase-module is equivalent to a buck-boost dc/dc converter, which allows the ac output voltages to be higher or lower than the dc input voltage. Thereby, the Y-VSI effectively copes with the wide variation of the fuel-cell/battery voltage. Each phase-module can be operated in a similar fashion to a conventional dc/dc converter, independently of the remaining two phases. Accordingly, a straightforward and simple operation/control of the Y-VSI is possible. In addition, the Y-VSI features an integrated output filter. This allows for continuous/sinusoidal motor voltage waveforms, eliminating the need for an additional filter between the inverter and the motor. This article details the operating principle of the Y-VSI and comparatively evaluates two modulation strategies. In order to validate the proposed concepts, a Y-VSI hardware prototype is assembled within the context of a high-speed motor drive. In the investigated drive system, a fuel-cell supplies the Y-VSI, which in return controls a 280-kr/min 1-kW electric compressor. The Y-VSI hardware prototype is compared against a state-of-the-art hardware prototype, which features two energy conversion stages. It is shown that the Y-VSI is <inline-formula> <tex-math notation="LaTeX">{\Delta \eta = +2.3 \%} </tex-math></inline-formula> more efficient and at the same time <inline-formula> <tex-math notation="LaTeX">{\Delta \rho = +10 \%} </tex-math></inline-formula> more power-dense compared with the conventional inverter solution.