Introduction
Partial discharge refers to the local breakdown phenomenon of the internal insulation structure of high-voltage power supplies under the action of a strong electric field. Although it will not immediately cause power supply failure, it will erode the insulation materials for a long time, seriously affecting the product service life and operational safety. In the niche customized production scenario of high-voltage power supplies, the control of partial discharge is more complex, requiring the formulation of plans combined with unique structural designs and process characteristics. This article will share niche and practical partial discharge control strategies from three core dimensions: insulation material selection, manufacturing process optimization, and electric field distribution regulation.
1. Precise Selection and Application of Niche Insulation Materials
The selection of insulation materials for high-voltage power supplies is the foundation for controlling partial discharge. Compared with commonly used materials such as epoxy resin and polytetrafluoroethylene, some niche high-performance materials are more suitable for partial discharge control under special working conditions. For example, modified polyimide films, by introducing nano-alumina particles, not only retain their original high-temperature resistance but also increase the breakdown field strength by more than 30%, and reduce the dielectric loss factor to below 0.002, which can effectively inhibit discharge phenomena caused by local electric field concentration.
In the manufacturing of high-frequency and high-voltage power supplies, a composite insulation structure of aluminum nitride ceramics and polyetheretherketone can be adopted. This niche combination not only utilizes the excellent thermal conductivity of aluminum nitride ceramics to control the local temperature rise of the insulation layer within 5℃ but also leverages the aging resistance of polyetheretherketone to reduce the erosion of materials by corona discharge. In addition, for high-voltage power supplies operating in low-temperature environments, hydrogenated nitrile rubber is selected as the auxiliary insulation material. It can maintain good elasticity even at -40℃ low temperature, avoiding microcracks caused by material embrittlement, thereby eliminating the breeding of partial discharge. During material selection, dielectric spectrum testing and partial discharge inception voltage tests are required to accurately match the dielectric parameters of the material with the working electric field strength of the power supply, ensuring the scientificity of the selection.
2. Refined Optimization Strategies for Manufacturing Processes
Minor deviations in the manufacturing process can lead to defects such as air gaps and impurities inside the high-voltage power supply, which become the source of partial discharge. Niche refined process optimization is the key to solving this problem. In the winding process, ultrasonic-assisted winding technology is adopted to remove the oxide layer and oil stains on the wire surface through 20kHz high-frequency ultrasonic vibration, making the wire arrangement tighter, reducing the air gap volume ratio to below 0.5%, and significantly reducing the possibility of air gap discharge.
For the potting process of high-voltage power supplies, the traditional vacuum potting method is abandoned, and a step-by-step pressure potting technology is adopted: first, inject the base potting compound at 0.3MPa pressure, let it stand for 2 hours, then supplement the potting at 0.6MPa pressure to effectively discharge the microbubbles inside the insulation layer. At the same time, the potting mold is treated with plasma before potting to improve the compatibility between the compound and the mold, avoiding gaps at the interface. In the electrode manufacturing process, electrochemical polishing is used instead of mechanical polishing to make the electrode surface roughness Ra≤0.05μm, reducing the concentration of electric field at the electrode tip and lowering the partial discharge inception voltage. Although these niche processes increase certain manufacturing costs, they can control the partial discharge capacity below 5pC, meeting the strict requirements of high-end customized power supplies.
3. Niche Regulation Technology for Electric Field Distribution
Uneven electric field distribution is the core inducement of partial discharge. In addition to common measures such as voltage equalizing rings and shielding covers, niche electric field regulation technologies can optimize the electric field distribution more accurately. At the end of the high-voltage winding of the high-voltage power supply, a gradient dielectric constant insulation structure is adopted. By gradient doping barium titanate powder in the insulation layer, the dielectric constant changes gradiently from 4.5 inside the winding to 2.2 outside, smoothing the mutation of electric field strength and reducing the local electric field peak by 40%.
For high-voltage power supplies in series with multiple modules, a capacitive voltage division electric field regulation scheme is adopted. Niche film capacitors are connected in parallel at the connection of each module, and the electric field distribution between each module tends to be uniform through the capacitive voltage division effect, avoiding partial discharge caused by uneven voltage distribution between modules. In addition, finite element simulation technology is used to accurately simulate the internal electric field of the power supply, identify the "electric field hot spots" prone to partial discharge, and adopt targeted measures such as local insulation thickening and electrode shape optimization to achieve directional regulation of electric field distribution. This niche electric field regulation method does not require significant changes to the overall structure of the power supply but can effectively improve the partial discharge control effect.
4. Construction of Process Detection and Quality Traceability System
The control of partial discharge is inseparable from the whole-process detection and traceability. Establishing a niche process detection system can timely detect defects in the manufacturing process. In the insulation material processing link, terahertz wave detection technology is adopted to perform non-destructive testing on microcracks and impurities inside the material, with a detection accuracy of 0.1mm, avoiding unqualified materials from flowing into the next process.
In the power supply assembly process, on-line partial discharge monitoring equipment is introduced to test the partial discharge of semi-finished products after key processes such as winding impregnation and potting curing. The test voltage is 1.3 times the rated working voltage. Once a product with a partial discharge capacity exceeding 10pC is found, it is reworked immediately. At the same time, a product quality traceability system is established to record the material batch, process parameters, and detection data of each power supply one by one, facilitating quick location of the cause when problems occur later. This niche detection and traceability model can control product quality from the source and reduce partial discharge hazards.
The control of partial discharge in the manufacturing process of high-voltage power supplies needs to jump out of the conventional schemes commonly used by the public. Combining niche materials, refined processes, precise electric field regulation, and whole-process detection can achieve efficient control under special working conditions and customized requirements. The strategies shared in this article can not only effectively inhibit partial discharge phenomena but also improve the reliability and stability of high-voltage power supplies, providing practical references for the research and development and production of niche high-voltage power supply products.
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