PCB Planar Transformer Winding for Partial Discharge Control
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Solution Overview
Problem
Existing medium voltage transformer designs face challenges in achieving partial discharge-free operation, high efficiency, better thermal performance, and modular manufacturability while managing insulation quality and electrical stress between primary and secondary windings.
Innovation Solution
A planar winding structure using a printed circuit board (PCB) with embedded conductive layers, shielding layers, grading rings, and EMI shielding to control electric fields and reduce partial discharge, combined with a magnetic core for transformer design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If litz wire is used for both primary and secondary sides, then the transformer can be constructed with conventional winding techniques, but the gap and bubble between litz wire strands are difficult to control during potting, resulting in poor insulation quality
Solution Approach 1:
The transformer is divided into two separate modules: a primary side module with primary windings and a magnetic core, and a secondary side module with secondary windings. This segmentation allows each module to be manufactured and potted independently, eliminating the insulation quality issues that arise from potting litz wire strands together. The primary and secondary windings are then coupled through magnetic coupling between the separate modules.
Solution Approach 2:
A magnetic core acts as an intermediary between the primary and secondary windings. Instead of having litz wire strands from both sides in close proximity requiring precise insulation control, the magnetic core provides magnetic coupling while maintaining physical separation. This intermediary allows electromagnetic energy transfer without direct electrical contact, eliminating the need for complex insulation management between primary and secondary litz wire strands.
2Reliability
If a gap is inserted between the core to separate transformer into LV and HV sides, then insulation requirements are mitigated, but the magnetic inductance becomes too small and circulating energy is too much for unnecessary conduction loss
Solution Approach 1:
The transformer is segmented into separate primary and secondary side modules that are magnetically coupled but electrically isolated. This segmentation allows the primary and secondary windings to be positioned close together for efficient magnetic coupling without requiring a large gap for insulation, thereby maintaining high magnetic inductance while still providing adequate insulation through the modular structure and potting material.
Solution Approach 2:
The insulation problem is solved by transitioning from a one-dimensional gap approach to a three-dimensional modular approach. Instead of creating a large gap between core sections, the invention uses separate modules positioned in close proximity with insulation provided by the potting material and winding structure itself, utilizing the third dimension (vertical stacking or close spacing) to achieve both insulation and magnetic coupling efficiency.
3Volume of moving object
If high frequency operation is used to reduce transformer footprint, then the passive transformer size can be reduced, but reliable insulation between high voltage and low voltage windings becomes more difficult to maintain
Solution Approach 1:
The transformer is divided into separate primary and secondary side modules that can be manufactured independently and then assembled. This segmentation allows each module to be optimized for its voltage level, with insulation designed specifically for that module's requirements. The modules are positioned close together for efficient high-frequency operation while maintaining reliable insulation through the modular structure and potting material, avoiding the need for excessive spacing that would increase footprint.
Solution Approach 2:
The primary and secondary windings within each module are positioned to achieve equipotential regions that minimize electric field stress. By carefully designing the winding layout and spacing within each module, the electric field between high voltage and low voltage windings is controlled, allowing reliable insulation even at high frequencies with reduced footprint. The magnetic core provides a reference potential that helps manage electric field distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The PCB-based planar winding structure achieves partial discharge-free operation, higher efficiency, improved thermal management, and easier manufacturing, while minimizing electrical stress and stray capacitance.
Implementation Method 1
a first winding disposed on the insulating planar board, the first winding wound around the through hole and proximate a periphery of the through hole; and a second winding disposed on the insulating planar board, the second winding wound around the through hole and spaced apart from the periphery of the through hole
Implementation Method 2
for use in a power transformer for medium voltage applications
Implementation Method 3
a shielding layer coated on outer surfaces of the winding portion of the insulating planar board in the winding portion
Implementation Method 4
a first grading ring embedded in the insulating planar board and extending in a horizontal direction from an interface of the winding portion and the terminal portion; and a second grading ring embedded in the insulating planar board and extending in the horizontal direction from the interface
Data Source
AI summary
The present disclosure provides a printed circuit board (PCB) based planar winding structure for a main power transformer and/or an auxiliary power need. The PCB-based planar winding structure can confine electric field through magnetic core potential control and thus create partial discharge (PD) free design for medium voltage (MV) applications. Meanwhile, the winding structure can be formed in the PCB manufacturing process to create a more modular and reliable structure, thereby enhancing manufacturability. Techniques, such as termination treatment, primary and secondary winding arrangements, etc., can be used to control the electrical stress in the medium voltage applications.