This paper proposes an open fault tolerant control for reducing switching loss in a three-level Si/SiC hybrid active neutral-point clamped (HANPC) inverter. The Si/SiC hybrid ANPC inverter consists silicon (Si) switches and silicon-carbide (SiC) switches. The HANPC inverter is more economical compared to the full SiC ANPC inverter and the full SiC ANPC inverter provides the high efficiency and power density almost the same as the full-SiC ANPC inverter. The Si switches operate with the low switching frequency according to the fundamental frequency, and the SiC switches have the high switching frequency depend on the carrier-based switching methods. The HANPC inverter has two neutral-states which make the pole voltage zero. Even if one of the Si switches for generating the neutral-states has an open fault, therefore, the inverter can output the normal three-phase current with the tolerant control. When the open fault tolerant control is applied, however, the Si switches operate with the high switching frequency same as the SiC switches. As a result, the Si switches have the high switching loss and overheat. To solve this problem, the fault tolerant control using discontinuous pulse width modulation (DPWM) is proposed in this paper. The proposed method is verified through simulation results.
This paper proposed the fault tolerant control for reducing switching loss in the three-level Si/SiC HANPC inverter. The Si/SiC HANPC inverter consists of Si-IGBTs and SiC-MOSFETs. The Si/SiC HANPC inverter has economical and efficient advantages compared to other three-level inverters. The Si-IGBTs operate with the fundamental frequency and the SiC-MOSFETs have the high switching frequency operation same to the carrier wave. If Sa2 for O\u2013-state is an open-fault, O+-state can apply instead. However, Sa3 and Sa4 operate in the high switching frequency even though these are Si-IGBTs. To reduce the increased switching loss, the proposed fault tolerant control was applied. The switching loss reduced about 55.4 % and the THD of output currents were improved from 1.62 % to 0.61 % due to clamped region. The proposed fault tolerant control was verified by the simulation results ACKNOWLEDGMENT This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. 2020R1G1A110040611).
