Mitigating Partial Discharge in Motor Winding Under Steep Voltage Pulses

Variable speed drives (VSDs) utilizing power electronic converters (PEC) allow precise motor speed control, resulting in energy savings. Nevertheless, the non-sinusoidal repetitive high-voltage pulses generated by PECs present a significant challenge to motor insulation, often resulting in premature breakdown. The intensified local electric stresses within the insulation of the windings trigger partial discharge (PD), resulting in the deterioration and aging of the winding. This study employs functional capacitive field grading composites (FCFGC) to inhibit PD occurrences in twisted wire pairs subjected to rapidly rising square waveforms. Experimental findings indicate that FCFGC can potentially diminish PD magnitudes and enhance Partial Discharge Inception Voltage (PDIV) compared to the neat Polydimethylsiloxane (PDMS) insulation. Additionally, the study includes the fabrication and characterization of FCFGC's permittivity. Electric field analyses of the twisted pair experiments are conducted using numerical models, incorporating the characterized field-dependent permittivity equation to offer a more comprehensive understanding of the experimental outcomes.