Anti-resonance phenomenon and peak voltage stress within PWM inverter fed stator winding

The high-frequency behavior of the stator winding is synthesized herein using a multi-conductor transmission line model to study the potential location of excessive voltage stress, being the main cause of insulation failure within the winding. The comprehensive modeling approach proclaims that the voltage distribution within the winding is a result of the anti-resonance phenomenon, which can be characterized by two oscillatory responses. One of the oscillatory response may lead to excessive voltage stress at the terminals of the machine, which have been reported extensively. However, it is the other oscillatory response, which engenders maximum voltage stress at the neutral end to the winding and prevails due to the superposition of traveling voltage waves. The latter is a sole characteristic of the stator winding and may be more detrimental to the winding insulation. Therefore, the stator winding remains under stress even with short or no cable. Furthermore, the paper illustrates that increasing the cable up to a certain length can be potentially treacherous. The simulation results validate the identified phenomenon through the high-frequency model of the cable and the stator winding developed in MATLAB/Simulink environment. Further, the experimental results verify the aforementioned phenomenon on an automotive-grade 60 kW permanent magnet synchronous machine (PMSM).