Partial Discharges in Motor Fed by Inverter: From Detection to Winding Configuration

Abstract

This paper reports non-intrusive partial discharge (PD) investigations on aeronautic and electric vehicle motors fed by inverter drive under variable environmental conditions. A representative test procedure and experimental setup based on operating aeronautic conditions are essential to ensure the accuracy and reliability of PD test on aircraft systems to make informed decisions on insulation system design choice. The aim of this paper is to demonstrate the feasibility of PD test of the insulation system on a different type of motor under such conditions, both electrically and environmentally. To do so, a study of the pressure influence on the frequency spectrum of discharges was carried out. This analysis defines the ability of the non-intrusive measurement system to detect PDs in equipment operating at low pressure. This paper also presents some tests on an industrial test bench to validate the ability of the non-intrusive test method and the associated numerical signal processing to detect PD in motors fed by PWM voltage. Then, an analysis is carried out on a motor to find out which voltage magnitude trigger PD events. The study helps to realize the benefits of using an inverter based test method to find the limits of the insulation system. It is shown that a representative insulation system performance picture could be drawn experimentally and used to enhance insulation design and manufacturing choices. The paper concludes with an analysis of results and thoughts about future work regarding advanced test procedure.