Implementation of three‑phase four‑leg inverter using SiC MOSFET for UPS applications

Jun-Hyeok Jegal; Minho Kwon; Chang-Yeol Oh; Kiryong Kim; Jong-Pil Lee

Implementation of three‑phase four‑leg inverter using SiC MOSFET for UPS applications

Vol. 21, No. 1, pp. 103-112, Jan. 2021

10.1007/s43236-020-00173-w

UPS

SiC MOSFET

Desaturation protection

Three-phase four-leg

Unbalanced loads

Abstract

This study implemented a 30 kW, 750 Vdc, silicon-carbide (SiC)-based uninterruptible power supply(UPS) applied it on a three-phase four-leg inverter. For component selection, LC filter and DC-link capacitor were designed based on the PSIM simulation. SiC MOSFET was used to achieve higher efficiency and better reliability than the conventional Si IGBT-based UPS applications. Furthermore, desaturation (DeSat) protection method was applied to protect the overcurrent during the short-circuit condition of SiC MOSFET. Thus, the DeSat protection method was applied to SiC MOSFET, thereby enabling a 1 μs protection by complementally switching and zener diode voltage optimization. Accordingly, the transient time of the DeSat protection can be disregarded, thereby enabling fast protection. Meanwhile, several topologies have been studied for unbalanced loads compensation. The current research used a three-phase four-leg inverter topology for compactness and neutral current control. In addition, voltage compensation became possible even in unbalanced load condition by introducing a dual-loop controller for the three-phase four-leg inverter. A dual-loop controller comprises PR and PI controllers to the stationary αβo and synchronous dqo reference frames, respectively. Thermal and efficiency tests were also performed in the rated power test. Under a 30 kW load condition, the surface epoxy molding compound temperature of SiC MOSFET was approximately 72 °C, and the highest efficiency was approximately 99.1% under 10 kW load condition. Finally, the effectiveness of the implementation was demonstrated through the experiment results.

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Cite this article

[IEEE Style]

J. Jegal, M. Kwon, C. Oh, K. Kim, J. Lee, "Implementation of three‑phase four‑leg inverter using SiC MOSFET for UPS applications," Journal of Power Electronics, vol. 21, no. 1, pp. 103-112, 2021. DOI: 10.1007/s43236-020-00173-w.

[ACM Style]

Jun-Hyeok Jegal, Minho Kwon, Chang-Yeol Oh, Kiryong Kim, and Jong-Pil Lee. 2021. Implementation of three‑phase four‑leg inverter using SiC MOSFET for UPS applications. Journal of Power Electronics, 21, 1, (2021), 103-112. DOI: 10.1007/s43236-020-00173-w.