Voltage distribution in the windings of an AC motor subjected to high dV/dt PWM voltages

In this paper voltage distribution in the windings of an induction motor subjected to PWM voltage waveforms is studied. A circuit model with the first few turns of the first coil modeled as a distributed transmission line is developed for a general purpose, mush wound low voltage induction motor. Inductance, resistance, mutual coupling and capacitance between turn to ground are incorporated into the proposed model. Simulation and experimental results are employed to validate the circuit model. Further, a 3 HP dual voltage 230/460 V induction motor with tappings from the first five turns and first coil is specially constructed. The motor is powered by an IGBT based PWM inverter and the measured voltage between the turns, and across the first coil are fully discussed. The test motor is also excited with sinusoidal 60 Hz voltage and the results are compared