| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 106 === This paper aims to investigate potential fault characteristics for Permanent Magnet Synchronous Motors (PMSM). The inverter switch short-circuit is the primary focus. When the inverter short-circuit fault occurs, considerable short-circuit currents are induced. They not only damage inverter devices, but also results in the demagnetization in PM motors.
Two common inverter short-circuit faults are investigated. They are respectively Symmetric Short-Circuit (SSC) Fault and Asymmetric Short-Circuit (ASC) Fault. For SSC fault, an analytical model is developed for the faulty motor drive. The influence of fault reflected short-circuit currents on PM motors with different parameters are analyzed. It is shown that the short-circuit current can be suppressed by properly selecting the motor parameters. In addition for ASC fault, the fault reflected short-circuit currents are significantly higher than the currents under SSC fault. A hardware protection strategy based on the SSC operating mode is proposed to mitigate these dangerous short-circuit currents, avoiding the risks in PM motors once ASC fault occurs.
All the analytical models will be verified by the inverter circuit simulation. In addition, Finite Element Analysis (FEA) is performed to investigate the demagnetization of PM motor under either SSC or ASC fault. Finally, two PM motors with different time constants are experimental evaluated to verity electromagnetic responses after fault.
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