Investigation of Surge Voltage Propagation in Inverter-Driven Electric Machine Windings

This article investigates what parameters affect the voltage propagation pattern in inverter-driven electric machine windings and presents mathematical analysis of this pattern with experiment verification. This work provides a thorough understanding of the behavior of machine windings under surge voltage excitations. First, high-fidelity finite element (FE) models were constructed with various combinations of factors in random-wound stranded machine windings. These factors include various types of parasitic capacitances, parasitic inductances of parallel strands, and different wire layouts in slots. The surge voltage distribution along the windings was simulated and compared among different cases to identify the key factors that affect this voltage propagation pattern. Subsequently, machine windings with both single-phase and three-phase structures were analyzed via equivalent circuits that were constructed with those key parameters. Then, the expressions of the coil voltage were derived in the Laplace domain. These expressions explicate the uneven surge voltage propagation pattern at various frequencies. Finally, for verification, both simulations and tests were conducted to analyze the surge voltage propagation in single-phase and three-phase windings.