The trend towards higher DC bus voltages and faster switching power electronics is driven by higher energy efficiency and more compact, lighter drivetrains. Today, the transition is mostly seen in automotive, but the industry will follow in the coming years, mainly because of the higher efficiency requirements. This trend to use fast switching SiC/GaN power electronics results not only in high efficiency and compactness, but also in an increased probability of damage in electric motor windings due to partial discharges in the insulation layers. It is also shown that another cause for degradation, thermal cycling, accelerates the damage caused by electrical partial discharges. Currently, these two coupled degradation phenomena can only be studied empirically.
In the Windam project, we aim to capture the combined thermo-electric degradation phenomena in a predictive assessment tool. The main goal of this tool for users is to check that there is a sufficiently high lifetime of their SiC/GaN drives. The tool will show the effect on winding degradation of several parameters: peak voltage on the windings, slew rate of the voltage waveform d𝑣/d𝑡, switching frequency of power electronics, temperature of windings and number of thermal cycles.
Windam will use a measurement campaign on motor windings to fit models for indicative lifetime. Windings will be tested mostly in motorettes (i.e. a segment of a stator of a motor), also in oil environment. Within Flanders Make, the equipment for doing these tests is already available and empirical degradation testing is already offered to companies: equipment to cause controlled degradation to windings and to monitor the progress of damage via state-of-health tests.
The assessment tool will be valid for a wide range of permanent magnet synchronous machines with hairpin or form-wound windings, both in automotive and industry applications. Windam will also describe which tests a company must do in order to use the tool for their own drivetrain products. In that way, Windam will increase the value of destructive testing by making the testing campaigns leaner and by providing predictive insight into the coupled thermo-electric degradation in motor windings.