Design of Experiments for Stator Windings Insulation Degradation under High dv/dt and High Switching Frequency

Abstract

SiC power devices are gaining increased interest due to their superior performance and increased efficiency in motor drives compared to traditional Si-based IGBT converters. However, the increased switching frequency and much faster switching transients (high dv/dt) of Silicon Carbide (SiC) compared to their IGBT counterparts, can result in increased stress in electrical machines. To quantify these detrimental effects on machine insulation lifetime, a series of tests are conducted on electrical stators representative of typical low voltage machines used in traction and industrial applications. A Design of Experiment (DoE) methodology is employed to identify the test sequence using three stressors. In particular, three values of DC link voltage level, rise time or slew rate of the voltage waveform, and switching frequency, respectively are considered. The paper describes the planned tests and conditions, the insulation health monitoring method employed, and preliminary results.