Simulation, test and analysis of three-phase short-circuit braking in IGCT-based MV adjustable speed drive systems

In the medium voltage adjustable speed drive (MV-ASD) systems, low switching frequency results in high harmonics in the output voltage waveform, which is harmful to the isolation of the induction motor. Therefore, the power filter is usually set between inverter and motor. However, self-excitation oscillation easily occurs under this structure due to the filter capacitor, which could continuously bring up the DC-link voltage of the inverter, and even destroy the devices in inverters. One of the effective ways to eliminate the self-excitation oscillation is to set the inverter to three-phase short-circuit braking state, which is described and analyzed in detail in this paper. Three-phase short-circuit braking could be easily realized in the inverter-motor system. It can be verified by both simulation based on PSIM and test results that this is an efficient way in real applications. Finally, the characteristics of the short-circuit braking is summarized and beneficial suggestions on using this braking method are presented.