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Electronics
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High-Voltage Technology and Its Applications
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High-Voltage Technology and Its Applications

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Power Electronics".

Deadline for manuscript submissions: 15 May 2025 | Viewed by 5489

Special Issue Editor

Dr. Mohamad Ghaffarian

E-Mail Website
Guest Editor
Department of Electrical Sustainable Energy, Delft University of Technology, 2628 CD Delft, The Netherlands
Interests: high voltage; aging of insulation material; high-voltage power electronics-based test sources; diagnostics and monitoring; medium-frequency transformers; power transformers; power cables; FEM-based modeling

Special Issue Information

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

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Electronics is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • 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

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Published Papers (5 papers)

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Research

15 pages, 5428 KiB  
Article
Design and Modeling Guidelines for Auxiliary Voltage Sensing Windings in High-Voltage Transformers and Isolated Converters
by Elinor Ginzburg-Ganz, Dmitry Baimel, Juri Belikov and Yoash Levron
Electronics 2025, 14(8), 1519; https://doi.org/10.3390/electronics14081519 - 9 Apr 2025
Viewed by 185
Abstract
This paper provides guidelines for designing and modeling sensing coils in high-voltage, high-frequency transformers to enable a cost-efficient design of isolated converter topologies. The objective is to design a magnetic structure in which an additional sensing coil, placed on the main transformer, can [...] Read more.
This paper provides guidelines for designing and modeling sensing coils in high-voltage, high-frequency transformers to enable a cost-efficient design of isolated converter topologies. The objective is to design a magnetic structure in which an additional sensing coil, placed on the main transformer, can be used to precisely measure the voltage on the secondary, despite fast changes in the voltage and current. This is usually a challenging task since high-voltage transformers will always require considerable isolation, which will give rise to significant leakage fields, which in turn will distort the measurement, especially at high frequencies. Our main finding is that this problem can be avoided if the sensing winding is carefully routed to maintain a certain ratio between the transformer’s coupling coefficients, which is achieved by placing this winding in an area within the core in which the magnetic field is low. In principle, this leads to a linear relationship between the voltages of the secondary and sensing windings despite non-ideal leakage inductances. The results are demonstrated experimentally using a 10 kW transformer, with 60 kV isolation, demonstrating a coupling coefficient of about 0.99, which reflects an error of less than 1.5% in the sensed secondary voltage. Full article
(This article belongs to the Special Issue High-Voltage Technology and Its Applications)
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25 pages, 6319 KiB  
Article
Research on the Effect of Nonlinear Variation in Insulation Resistance on the Voltage Divider Ratio of 2 × 550 kV DC Voltage Proportional Standard Device
by Yin Gao, Ximing Chen, Yuqing Duan, Ran Gao, Chao Wang, Zheng Chen, Fei Lin, Lei Zhuang, Wanjun Zhu, Min He and Liang Qin
Electronics 2025, 14(1), 138; https://doi.org/10.3390/electronics14010138 - 31 Dec 2024
Viewed by 637
Abstract
This paper investigates the effect of nonlinear changes in insulation resistance on the accuracy of a 2 × 550 kV DC voltage scaling standard device. As the voltage and electric field strength increase, the insulating material exhibits nonlinear conductivity characteristics, leading to a [...] Read more.
This paper investigates the effect of nonlinear changes in insulation resistance on the accuracy of a 2 × 550 kV DC voltage scaling standard device. As the voltage and electric field strength increase, the insulating material exhibits nonlinear conductivity characteristics, leading to a decrease in the insulation resistance value, which in turn affects the potential distribution and the partial voltage ratio and thus reduces the measurement accuracy of the standard device. In order to study this problem in depth, this paper builds a nonlinear resistance measurement platform for insulating materials, and it fits and analyzes the experimental data using an NCIR neural network (Neural Network for Nonlinear Characteristics of Insulation Resistance). In addition, in this paper, the finite element model of the standard device was established by ANSYS simulation, and the equivalent resistance network model was established by applying MATLAB in order to calculate the variation in the voltage dividing ratio under different voltages. The results of the study showed that the nonlinear variation in insulation resistance significantly affects the voltage division ratio of the standard device, especially at high voltage conditions. Addressing the issue, this paper proposes to optimize the electric field distribution by optimizing the structure of the grading ring and adding a shielding resistor layer to reduce the influence of nonlinear effects. Simulation results show that the addition of a second layer to the shielding resistor can effectively improve the measurement accuracy of the device, and the reduction in voltage division ratio error is significant. Compared with the case of a shielding resistor with only one layer, the voltage divider ratio was reduced from 109,998.203 to 109,998.994, and the relative error was reduced 44%, changing from 1.634 × 10−5 to 9.15 × 10−6. The above study provides an optimized solution for achieving high-precision DC voltage measurement. Full article
(This article belongs to the Special Issue High-Voltage Technology and Its Applications)
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32 pages, 7028 KiB  
Article
Detection of Faulty Energizations in High Voltage Direct Current Power Cables by Analyzing Leakage Currents
by Kumar Mahtani, Ricardo Granizo, José M. Guerrero and Carlos A. Platero
Electronics 2024, 13(20), 4120; https://doi.org/10.3390/electronics13204120 - 19 Oct 2024
Cited by 2 | Viewed by 1088
Abstract
The use of multi-terminal high voltage direct current (HVDC) power transmission systems is being adopted in many new links between different generation and consumption areas due to their high efficiency. In these systems, cable energization must be performed at the rated voltage. Healthy [...] Read more.
The use of multi-terminal high voltage direct current (HVDC) power transmission systems is being adopted in many new links between different generation and consumption areas due to their high efficiency. In these systems, cable energization must be performed at the rated voltage. Healthy energizations at the rated voltage result in large inrush currents, especially in long cables, primarily due to ground capacitance. State-of-the-art protection functions struggle to distinguish between transients caused by switching and those associated with ground faults, leading to potential unwanted tripping of the protection systems. To prevent this, tripping is usually blocked during the energization transient, which delays fault detection and clearing. This paper presents a novel method for prompt discrimination between healthy and faulty energizations. The proposed method outperforms conventional protection functions as this discrimination allows for earlier and more reliable tripping, thus avoiding extensive damage to the cable and the converter due to trip blocking. The method is based on the transient analysis of the current in the cable shields, therefore, another technical advantage is that high voltage-insulated measuring devices are not required. Two distinct tripping criteria are proposed: one attending to the change in current polarity, and the other to the change in current derivative sign. Extensive computer simulations and laboratory tests confirmed the correct operation in both cases. Full article
(This article belongs to the Special Issue High-Voltage Technology and Its Applications)
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34 pages, 25979 KiB  
Article
Comprehensive Investigation of Promising Techniques to Enhance the Voltage Sharing among SiC MOSFET Strings, Supported by Experimental and Simulation Validations
by Weichuan Zhao, Sohrab Ghafoor, Gijs Willem Lagerweij, Gert Rietveld, Peter Vaessen and Mohamad Ghaffarian Niasar
Electronics 2024, 13(8), 1481; https://doi.org/10.3390/electronics13081481 - 13 Apr 2024
Cited by 4 | Viewed by 1621
Abstract
This paper comprehensively reviews several techniques that address the static and dynamic voltage balancing of series-connected MOSFETs. The effectiveness of these techniques was validated through simulations and experiments. Dynamic voltage-balancing techniques include gate signal delay adjustment methods, passive snubbers, passive clamping circuits, and [...] Read more.
This paper comprehensively reviews several techniques that address the static and dynamic voltage balancing of series-connected MOSFETs. The effectiveness of these techniques was validated through simulations and experiments. Dynamic voltage-balancing techniques include gate signal delay adjustment methods, passive snubbers, passive clamping circuits, and hybrid solutions. Based on the experimental results, the advantages and disadvantages of each technique are investigated. Combining the gate-balancing core method with an RC snubber, which has proven both technically and commercially attractive, provides a robust solution. If the components are sorted and binned, voltage-balancing techniques may not be necessary, further enhancing the commercial viability of series-connected MOSFETs. An investigation of gate driver topologies yields one crucial conclusion: magnetically isolated gate drivers offer a simple and cost-effective solution for high-frequency (HF) applications (2.5–50 kHz) above 8 kV with an increased number of series devices. Below 8 kV, it is advantageous to move the isolation barrier from the gate drive IC to an optocoupler and isolated supply, allowing for a simple design with commercially available components. Full article
(This article belongs to the Special Issue High-Voltage Technology and Its Applications)
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13 pages, 3775 KiB  
Article
Optimal Design of Voltage Equalization Ring for the 1100 kV DC Voltage Proportional Standard Device Based on the Nation Standard Device Neural Network and Grey Wolf Optimization Algorithm
by Wanjun Zhu, Yin Gao, Liang Qin, Yuqing Duan, Zhigang Bian, Min He and Kaipei Liu
Electronics 2024, 13(7), 1308; https://doi.org/10.3390/electronics13071308 - 31 Mar 2024
Viewed by 1023
Abstract
The DC voltage ratio standard device is an important tool for calibrating DC voltage transformers. At the 1100 kV voltage level, an increase in electric field intensity will increase the local heat generated inside the device, affecting the accuracy of its measurement. Using [...] Read more.
The DC voltage ratio standard device is an important tool for calibrating DC voltage transformers. At the 1100 kV voltage level, an increase in electric field intensity will increase the local heat generated inside the device, affecting the accuracy of its measurement. Using a suitable grading ring can even out the electric field intensity and reduce the maximum field strength to improve its measurement accuracy. This article mainly optimizes the design of the grading-ring structure of the 1100 kV DC voltage ratio standard device. First, a finite-element model of the 1100 kV DC voltage ratio standard device was built based on ANSYS; the electric field distribution around the voltage divider was calculated and analyzed, and a data set was constructed based on the calculation results. Secondly, for the optimization of electric field strength, this article presents the design of the nation standard device neural network, which learns the relationship between the structural parameters of the toroidal core and the field strength under the PyTorch 1.8 deep learning framework. Due to the strong convergence performance, few parameters, and ease of implementation of the grey wolf optimization algorithm, this study selected this algorithm to optimize the structural parameters of the grading ring. Finally, simulation examples are established in Python for validation. The experimental results indicate that the maximum field strength of the grading ring decreased from 12,161.1348 V/cm to 10,009.2881 V/cm, a reduction of 17.69%. The optimized structural parameters of the grading ring effectively reduced the electric field intensity around the 1100 kV DC voltage proportional standard device, providing a reliable and practical design approach for the selection of the DC voltage ratio standard device. Full article
(This article belongs to the Special Issue High-Voltage Technology and Its Applications)
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