Research on Volume Optimization of Partial Discharge-Free Variable Frequency Test Power Supply Based on Magnetic Integration Technology

Partial discharge-free variable frequency test power supply is a key equipment for insulation performance testing of electrical equipment, widely used in partial discharge testing of high-voltage equipment such as transformers, cables, and GIS. Its core requirements are low output waveform distortion rate and small partial discharge (typically required to be ≤5pC), while also meeting the portability needs of on-site testing. Traditional partial discharge-free variable frequency test power supplies suffer from bulky magnetic components (such as isolation transformers and filter inductors) and dispersed layouts, resulting in heavy overall equipment (some models weighing over 50kg), which limits their flexible application in complex on-site environments. Magnetic integration technology, by integrating the magnetic circuits and structures of multiple magnetic components, can significantly reduce magnetic core material usage and space occupation, providing an innovative solution for power supply volume optimization. This paper, based on the performance requirements of partial discharge-free variable frequency test power supplies, explores the application principles, design methods, and practical effects of magnetic integration technology in volume optimization.

Volume Bottlenecks of Traditional Partial Discharge-Free Variable Frequency Test Power Supplies

The core modules of partial discharge-free variable frequency test power supplies include variable frequency control units, power conversion units, magnetic component units, and filtering units. Among these, magnetic components (isolation transformers, output filter inductors, resonant inductors, etc.) are the main contributors to volume and weight, accounting for 40%~60% of the overall equipment volume. In traditional designs, each magnetic component is independently designed and dispersedly laid out, leading to the following issues:

1. Low Utilization Rate of Magnetic Core Materials
Independent magnetic components each require magnetic circuit fulfillment, with magnetic core window space underutilized, leading to material waste. For example, isolation transformers require large insulation distances for electrical isolation, while filter inductors need reserved air gaps to reduce ripple, both resulting in "single-function, space-redundant" magnetic core issues.

2. Dispersed Structural Layout
Mounting brackets and cooling gaps for independent components further increase overall volume. Taking a 10kV/5kVA traditional partial discharge-free power supply as an example, the total occupied space of the isolation transformer (approximately 200mm×150mm×120mm) and filter inductor (approximately 180mm×120mm×100mm) exceeds 40L, far exceeding the total volume of electronic component modules.

3. Electromagnetic Interference and Loss Superposition
Dispersedly laid magnetic components have mutual inductance coupling, easily generating electromagnetic interference (EMI). To meet partial discharge-free performance requirements, additional shielding structures are needed, further increasing volume.

Magnetic Integration Technology: Core Path for Volume Optimization

Magnetic integration technology fundamentally solves traditional design volume redundancy issues through "magnetic circuit sharing and structural merging," integrating the functions of multiple independent magnetic components into a single magnetic core. Its core principle utilizes magnetic field superposition and isolation characteristics to achieve various electromagnetic functions (such as voltage transformation, filtering, energy storage, etc.) within the same magnetic core, with specific optimization mechanisms as follows:

1. Magnetic Circuit Sharing: Reducing Magnetic Core Quantity and Materials
In traditional designs, isolation transformers and filter inductors have independent magnetic circuits requiring two sets of magnetic cores. Magnetic integration technology, through designing special magnetic core structures (such as E-type, pot-type, planar magnetic cores), enables the transformer's main magnetic flux and inductor's excitation magnetic flux to flow along preset paths within the same magnetic core, achieving "one core, multiple uses." For example, in integrated transformer-inductor modules, transformer primary and secondary windings are wound on the main core column, while inductor windings are wound on side columns. By adjusting magnetic core air gap position and size, transformer turns ratio and inductor inductance values are controlled separately, reducing magnetic core material usage by 30%~50%.

2. Structural Integration: Improving Space Utilization Rate
Magnetic integrated components integrate multiple functional windings on the same magnetic core, reducing shells, brackets, and installation gaps of independent components. Taking planar magnetic integration structures as an example, using thin magnetic cores and planar windings can reduce transformer and inductor height from the traditional 120mm to below 60mm, while further compressing horizontal space through multilayer PCB winding designs. In one case, the integrated magnetic component volume decreased by 60% compared to independent solutions, with weight reduced by 45%.

3. Electromagnetic Compatibility Optimization: Reducing Shielding Requirements
Magnetic integration design, through magnetic circuit directional constraints, can reduce leakage magnetic interference between components. For example, using closed magnetic core structures and symmetrical winding layouts confines leakage flux within the magnetic core, meeting the stringent electromagnetic environment requirements for partial discharge testing (partial discharge ≤5pC) without additional shielding.

Practical Design of Power Supply Volume Optimization Based on Magnetic Integration

Taking a 20kV/10kVA partial discharge-free variable frequency test power supply as an example, magnetic integration technology was used for volume optimization with the following specific design steps:

1. Magnetic Component Functional Integration Planning
Analyzing the power supply topology to determine magnetic components requiring integration: isolation transformer (achieving high-low voltage isolation), output filter inductor (filtering high-frequency ripple), and resonant inductor (cooperating with capacitors for variable frequency output). Through magnetic circuit simulation, the three were integrated into a -shaped magnetic core: main column wound with transformer primary and secondary windings, left side column wound with filter inductor windings, right side column wound with resonant inductor windings, with high-permeability ferrite (PC40) selected as the magnetic core material to reduce losses.

2. Collaborative Design of Magnetic Core and Winding Parameters
By adjusting magnetic core window dimensions (width×height=150mm×80mm) and winding layers (4 layers for transformer windings, 2 layers for inductor windings), ensuring ampere-turns and insulation distances of each functional winding meet requirements. Segmented winding processes were used to reduce winding losses, while finite element simulation optimized air gap positions, achieving transformer turns ratio error ≤1% and inductor inductance deviation ≤5%.

3. Compact Overall Structural Layout
The integrated magnetic core module and power switches, capacitors, and other components adopted a "three-dimensional stacking" layout, utilizing the magnetic core's top space for control board installation and reserving cooling air ducts at the bottom. The final power supply overall dimensions were reduced from the traditional 600mm×400mm×300mm (volume 72L) to 450mm×300mm×200mm (volume 27L), with volume reduced by 62.5% and weight decreased from 65kg to 32kg.

Performance Verification and Application Value

The optimized partial discharge-free variable frequency test power supply passed authoritative agency testing with the following key performance indicators:

· Volume and Weight: Compared to traditional solutions, volume reduced by 62.5% and weight by 50.8%, meeting on-site handling requirements;

· Partial Discharge-Free Performance: At 20kV output voltage, partial discharge ≤3pC, superior to national standard requirements (≤5pC);

· Efficiency: Full-load efficiency improved to 92% (traditional solution was 88%) due to magnetic integration reducing magnetic core losses;

· Electromagnetic Compatibility: Conducted and radiated disturbances both meet GB/T 17626.6-2017 Class A limits.

Conclusion and Outlook

Magnetic integration technology, through magnetic circuit sharing and structural integration, solves the magnetic component volume redundancy problem in partial discharge-free variable frequency test power supplies, achieving equipment lightweight and portability. In the future, combined with wide-bandgap semiconductors and new magnetic core materials, power density can be further improved, promoting test power supply development toward "miniaturization, modularity, and intelligence."

With over a decade of expertise in the power supply field, lcxpower.com, through "magnetic circuit collaborative design + structural integrated packaging," compresses traditional separate transformers and filter inductors by 60% in volume, reducing overall weight from 80kg to 32kg. Using three-dimensional magnetic circuit simulation to optimize magnetic core structures and leveraging nanocrystalline alloy magnetic core high saturation flux density characteristics, maintaining ±0.1% voltage precision and ≤1pC partial discharge.

This technology, in testing at a certain ±800kV UHV converter station, saved 50% in transportation costs, reduced deployment time from 2 days to 4 hours, and maintained stable output in high-altitude environments.

In the future, lcxpower.com will deploy "magnetic integration + wide-bandgap semiconductor" collaborative innovation, increasing power density to 5kW/kg and developing modular quick-change interfaces. If your power testing faces issues such as bulky equipment and low deployment efficiency, lcxpower.com will provide customized miniaturized partial discharge-free test power supplies, ushering on-site testing into a "lightweight, precise, and efficient" new era.