Planar Air-Core Transformer with Partial EMI Shielding for Isolation
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Solution Overview
Problem
Existing transformers face challenges in achieving high coupling efficiency while meeting stringent electromagnetic interference (EMI) standards, particularly in automotive and industrial applications, leading to increased costs and system footprint due to the need for additional EMI filters.
Innovation Solution
A symmetric air-core planar transformer design with partial electromagnetic interference (EMI) shielding is implemented, utilizing a multilayer laminate substrate with coils on multiple metal layers and partial EMI shields to maintain isolation while enhancing coupling efficiency and reducing EMI, achieved by using copper clad laminates and pre-pregs with controlled copper thickness and symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional transformer designs are used to achieve isolation, then isolation protection is provided, but coupling efficiency is reduced and EMI standards are not met
Solution Approach 1:
The transformer is divided into multiple planar layers with primary and secondary windings distributed across different layers. This segmentation allows for optimized coupling paths while maintaining isolation barriers between layers, resolving the contradiction between achieving isolation protection and maintaining high coupling efficiency.
Solution Approach 2:
The patent transitions from traditional three-dimensional wound transformers to a planar two-dimensional layered structure. This dimensional change enables better control over magnetic coupling paths and isolation barriers, simultaneously achieving high coupling efficiency and meeting EMI standards.
2Reliability
If traditional transformer designs are used, then isolation protection is provided, but EMI standards are not met requiring additional filters
Solution Approach 1:
The patent extracts and removes the need for external EMI filters by integrating EMI suppression functionality directly into the transformer structure through planar shielding layers and optimized winding arrangements, eliminating harmful electromagnetic interference while maintaining isolation protection.
Solution Approach 2:
Planar shielding layers are introduced as intermediary elements between primary and secondary windings. These shielding layers act as mediators that block electromagnetic interference paths while allowing magnetic coupling to pass through, thereby meeting EMI standards without compromising isolation protection.
3Object-affected harmful factors
If additional EMI filters are added to meet standards, then EMI compliance is achieved, but system footprint and cost increase
Solution Approach 1:
The patent merges EMI filtering functionality with the transformer structure itself by integrating planar shielding layers and optimized winding configurations. This consolidation eliminates the need for separate external EMI filters, reducing system footprint while achieving EMI compliance.
Solution Approach 2:
The transformer structure is designed to perform multiple functions simultaneously: power isolation, magnetic coupling, and EMI suppression. This multi-functionality is achieved through planar shielding layers that provide both structural support and EMI filtering, eliminating the need for additional dedicated EMI filter components.
4Object-affected harmful factors
If additional EMI filters are added, then EMI compliance is achieved, but system cost increases
Solution Approach 1:
The patent merges EMI filtering functionality with the transformer structure itself, eliminating the need for separate external EMI filter components. This consolidation reduces bill of materials costs and assembly complexity, thereby reducing overall system cost while achieving EMI compliance.
Solution Approach 2:
The transformer is designed as a multi-functional component that provides isolation, coupling, and EMI suppression in a single integrated structure. This eliminates the need for multiple separate components, reducing manufacturing complexity and system cost while maintaining EMI compliance.
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 meets stringent EMI standards with improved coupling efficiency, reducing the need for additional EMI filters and minimizing system footprint and cost, while maintaining high isolation voltage protection.
Implementation Method 1
A first multiloop coil has at least a first loop on the first metal layer and at least a second loop on the second metal layer. A second multiloop coil has at least a third loop on the third metal layer and at least a fourth loop on the fourth metal layer.
Implementation Method 2
A partial EMI shield for the first multiloop coil is on the second metal layer. A partial EMI shield for the second multiloop coil is on the third metal layer.
Data Source
AI summary
A laminate transformer includes a multilayer substrate having at least first, second, third, and fourth metal layers. The second metal layer and the third metal layer are separated by a voltage barrier having a thickness. A first multiloop coil has at least a first loop on the first metal layer and at least a second loop on the second metal layer. A second multiloop coil has at least a third loop on the third metal layer and at least a fourth loop on the fourth metal layer. A partial EMI shield for the first multiloop coil is on the second metal layer. A partial EMI shield for the second multiloop coil is on the third metal layer.