High frequency equivalent circuit model of the stator winding in electrical machines

Over the years, electrical machinery design strategies have been mainly oriented towards enhancing the output power, power density and torque. However, the effect of machine parameters (geometry, material properties, etc.) on stress and life expectancy has not been considered very often. Since the machines are designed to be as compact as possible, they tend to operate at levels closer to their safety margins. Moreover, the substantial growth in inverter supplying has introduced excessive electrical stress to the winding insulation. This results into earlier partial discharge and bearing currents which may be analyzed by the models that are valid in the high frequency spectrum. This paper introduces a model that can be used to monitor the health-status of the machine´s winding by studying these effects. The approach introduced in this paper can localize the mostly stressed parts of the winding fed by inverter by means of measurement and simulation.