Planar Transformer High-Voltage Isolation via PCB Stress Grading
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Solution Overview
Problem
Traditional high-voltage isolation transformers are bulky and have difficulty meeting high isolation withstand voltage requirements, while existing planar transformers are limited to low isolation voltage applications due to their compact structure and limited insulation distance between windings.
Innovation Solution
A high-voltage isolation planar transformer design incorporating low-voltage and high-voltage windings, a PCB stress grading unit, and voltage-balancing elements to control electric field distribution and increase insulation distance, utilizing a multilayer PCB structure with stress control bars and an insulating medium for enhanced insulation and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional insulation methods (epoxy potting, transformer oil immersion) are used to achieve high-voltage isolation, then the isolation withstand voltage between high-voltage and low-voltage windings is achieved, but the system size increases significantly and the magnetic core grounding and terminal insulation are not properly addressed
Solution Approach 1:
The patent segments the insulation function into multiple components: PCB insulating medium for winding isolation, stress control bars for electric field management, and voltage-balancing elements for potential gradient control. This segmentation allows high-voltage isolation to be achieved without requiring a single large insulating structure, thus reducing overall system size while maintaining reliability
Solution Approach 2:
The patent introduces stress control bars as intermediary elements between the high-voltage and low-voltage windings. These bars, combined with voltage-balancing elements, act as mediators to control the electric field distribution and manage insulation stress, enabling effective isolation without excessive insulation gaps that would increase system size
2Reliability
If the insulation gap is increased to improve terminal insulation, then the insulation performance is enhanced, but the transformer size increases and electric field stress concentration at terminals is not resolved
Solution Approach 1:
The patent applies local quality by placing voltage-balancing elements specifically at the terminal regions where electric field stress concentration occurs. These elements create localized potential gradients that manage the electric field stress at critical points without requiring a uniform increase in insulation gap across the entire transformer, thus improving terminal insulation performance while minimizing size increase
3Volume of stationary object
If planar transformer structure is used to reduce size and improve power density, then the height is greatly reduced and power density increases, but the insulation distance between primary and secondary windings is limited to low isolation voltage applications (≤4 kV)
Solution Approach 1:
The patent transitions from traditional three-dimensional winding structures to a planar two-dimensional PCB-based structure. By utilizing the layered structure of multilayer PCBs and arranging windings in different planes separated by insulating medium, the patent achieves effective insulation distance in a compact form factor, enabling high isolation voltage capability while maintaining reduced size and high power density
4Ease of manufacture
If traditional transformers are assembled by winding copper coils on magnetic core, then the structure is established, but the volume is large and parasitic parameters are hard to control, making it difficult to ensure product parameter consistency
Solution Approach 1:
The patent replaces the mechanical winding process with PCB-based planar windings. The PCB manufacturing process provides precise control over trace dimensions, positions, and layer alignment, automatically ensuring consistent parasitic parameters and product characteristics without requiring manual winding skills and quality control, thus improving ease of manufacture and parameter consistency while reducing volume
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 design achieves high power density, consistent parameters, and reduced size, effectively addressing the limitations of traditional transformers and planar transformers by controlling electric field strength and preventing partial discharge, thus enabling high-voltage isolation in compact form factors.
Implementation Method 1
an insulating medium configured for high-voltage isolation between the low-voltage and the high-voltage windings
Implementation Method 2
the PCB stress grading unit is configured to control the distribution of an electric field around the high-voltage winding leading-out foil and reduce an electric field strength in air
Implementation Method 3
the voltage-balancing element group is configured to provide a voltage potential with a gradient change
Data Source
AI summary
A high-voltage isolation withstand planar transformer and its high-voltage insulation method are provided. An insulating medium is provided between low-voltage windings and high-voltage windings. High-frequency current flows through the windings and generates a high-frequency alternating magnetic field to achieve isolated energy transmission. The low-voltage windings are connected to low-voltage side connection terminals, and the high-voltage windings are connected to high-voltage side connection terminals through a high-voltage winding leading-out foil. An annular hollow part of the low-voltage windings and the high-voltage windings is provided with a magnetic core. A stress grading method is provided to control the distribution of the electric field around the high-voltage winding leading-out foil. A voltage-balancing element group provides a voltage potential with a gradient change between the high-voltage winding leading-out foil and the low-voltage windings. The new transformer has small size, high power density and low cost.