Characterization, Multiphysics Modeling and Mitigation of Insulation Material Degradation and Breakdown
Abstract
Wide bandgap (WBG) devices made from materials such as SiC, GaN, Ga2O3, and diamond can tolerate high voltages and currents and are the most promising approach for reducing the size and weight of power management and conversion systems. These systems are envisaged to be widely used in next-generation aircraft, which are expected to be more electric or, possibly, all-electric. However, accelerated aging of solid dielectrics used in various apparatuses for electrification of aircraft under fast (slew rates (dv/dt) ranging from tens to hundreds of kV/ks) and repetitive voltage pulses (frequencies ranging from hundreds of kHz to MHz) originating from WBG-based systems can offset or even be an obstacle to using WBG-based systems. To date, the combination of (1) fast, repetitive voltage pulses with the specifications above, (2) low-pressure environments, and (3) harsh conditions, which are expected to lead to the worst accelerated insulation aging, has not been experimentally or theoretically researched. This lack of experimental and theoretical information prevents us from having a clear understanding of the phenomena behind insulation degradation, which eventually leads to the breakdown of solid dielectrics. Without a clear understanding of these're-breakdown mechanisms, developing effective methods to mitigate accelerated aging is impossible. The discovery of new dielectrics is one solution to the problem of accelerated aging under the combined conditions described above. However, we believe there is another solution, which we call critical frequency, that is in accord with the trend toward increasing the switching frequency of WBG-based systems. Although the lifetime of solid dielectrics and breakdown voltages in air decrease with frequency, they reach a saturation limit at the critical frequency; thus, working above this frequency might resolve the accelerated aging issue.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 21, 2024
- Accession Number
- AD1230731
Entities
People
- Safaai-jazi Ahmad
Organizations
- Virginia Tech