High-Voltage Technology and Its Applications

Dear Colleagues,

Due to the energy transition, a massive amount of power electronics (PE) will be integrated into the medium- and high-voltage (MV/HV) grid, as well as emerging applications like electric aircraft. The design of insulation systems for such high-voltage PE-based devices lacks comprehensive guidelines at present. For example, the high-frequency PWM stress with high dv/dt generated by PE devices accelerates insulation aging at higher rates compared to the traditional 50 Hz sinusoidal waveform, something which is not fully understood and characterized. Ongoing developments, such as the introduction of new SiC MOSFETs with voltage ratings exceeding 10 kV, amplify these challenges, affecting both the design of their own packaging and the insulation degradation of devices connected to such switches. The medium-frequency transformer (MFT), a key component in power converters, is an example of such devices that is subjected to these type of stresses. At MV/HV levels, the insulation system of MFT becomes a critical design consideration, necessitating proper guidelines.

As the grid becomes more dependent on power electronics devices, the diagnostics and monitoring of MV/HV power electronics components need more attention and development. Currently, temperature monitoring, as well as fast protection against short circuit currents, is implemented. That said, other diagnostics and monitoring techniques, such as PD measurement, reverse conduction current, drain-source voltage drop, etc., can also be used to predict the condition of the devices. Furthermore, while traditional power devices are being tested for under line frequency, lightning, and switching overvoltages, for MV/HV PE-based devices, fulfilling all of those requirements demands significant oversizing. As such, alternative standards for testing and qualification are needed.

The primary objective of this Special Issue is to explore insulation system design, testing, diagnostics and monitoring, and the estimation of the remaining lifetimes of medium- and high-voltage power electronics-based devices, as well as the components connected to them. Research areas may include (but are not limited to) the following subjects:

High-voltage power electronics-based test sources:

• High-voltage amplifiers and power supplies;
• Resonant and pulse transformer based test circuits;
• High voltage challenges in power converters;
• Voltage balancing and series connection of switches;
• Gate deriver design for high voltage switches.

Insulation aging, remaining lifetime, and diagnostics and monitoring of power electronics-based devices

• Insulation degradation and aging mechanisms;
• Impact of high voltage PWM, pulse, harmonics, and combined AC/DC stress on insulation material;
• Potting material and techniques, and aging of PCBs;
• PD measurement under high-frequency and pulse stress;
• Remaining lifetime estimation of power electronics-based devices;
• Diagnostics and monitoring of medium voltage PE-based devices.

Medium-frequency transformers and power transformers:

• Insulation system design (oil immersed, dry type, epoxy casting, clearances, etc.);
• Field grading and bushing design;
• R, L, C parameters calculation;
• Loss calculation;
• High-frequency transformer modeling;
• Thermal analysis;
• Testing;
• Optimization of transformer design.

Power Cables

• High-voltage cabling of electric aircraft;
• HVDC cables and their accessories;
• Insulation aging and space charges;
• Partial discharge detection and localization;
• Dynamic cables.

In this Special Issue, original research articles and reviews are welcome. We look forward to receiving your contributions.

Dr. Mohamad Ghaffarian
Guest Editor

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• high voltage
• power electronics
• high-volatge power electronics-based test sources
• pulse stress
• insulation aging
• remaining lifetime of high-voltage components
• diagnostics and monitoring
• medium-frequency transformers
• power transformers
• power cables
• high-voltage issues in electric aircraft