Investigation of Loss Characteristics in SiC-MOSFET Based Three-Phase Converters Subject to Power Cycling and Short Circuit Aging

In order to verify the stability of eco-friendly mobility and the use of renewable energy, research on reliability of power semiconductor used for power conversion system is being conducted. In particular, research on Silicon-carbide Metal Oxide Semiconductor (SiC-MOSFET) is being actively conducted. In SiC-MOSFET, gate-oxide layer or package are aged due to electrical and thermal stress generated during operation. In this case, the aged transistor not perform as expected, and may cause a failure of power conversion system. In this paper, to investigate the influence of SiC-MOSFET aging on the power conversion system, power loss and efficiency variation of the system are analyzed. To accelerate the transistor aging, two aging methodologies are used: Power Cycling (PC) and Short Circuit (SC) aging. And then, through a double-pulse test (DPT), power loss variation of the aged transistor is measured and modeled. After that, to analyze the effect of the aged transistor on the system, the power loss modeling is applied to three-phase grid-connected converter. As a result, when using the transistor aged by SC, there are a larger efficiency decrease than when using the transistor aged by PC. In addition, the increase in transistor conduction loss is larger than other losses.