Segmented Transformer Winding Layout for Capacitance Control
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Solution Overview
Problem
Existing transformers, particularly those used in gate-drive circuits and open-loop LLC converters, face challenges with high winding-to-winding capacitance and leakage inductance variability, leading to noise and imprecision in circuit behavior.
Innovation Solution
A transformer design featuring a core portion with specific lengthwise regions and windings where the primary and secondary windings are wound in a reversible pattern with constant turn spacing, forming a winding-to-winding capacitor with reduced capacitance and controlled leakage inductance, and an upper core portion attached with gaps to enhance energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional winding arrangements are used in transformers, then the structure is simple and easy to manufacture, but the winding-to-winding capacitance is high and leakage inductance varies significantly
Solution Approach 1:
The winding is divided into multiple sections with different turn densities along the core length. Specifically, the primary winding has higher turn density near the distal end and lower turn density near the endpoint, while the secondary winding has the opposite distribution. This segmentation allows independent optimization of capacitance and leakage inductance characteristics.
Solution Approach 2:
Different regions of the winding have different properties (turn densities) tailored to local requirements. The distal end regions have higher turn density to reduce capacitance, while the endpoint regions have lower turn density to control leakage inductance. This local quality variation resolves the contradiction between capacitance reduction and leakage inductance stability.
2Reliability
If winding turns are placed close together to reduce leakage inductance, then leakage inductance decreases, but winding-to-winding capacitance increases
Solution Approach 1:
The winding is segmented into regions with different spacing characteristics. Near the distal ends where capacitance is critical, turns are spaced further apart. Near the endpoints where leakage inductance is more critical, turns are placed closer together. This spatial segmentation allows simultaneous optimization of both parameters.
Solution Approach 2:
The primary and secondary windings have asymmetric turn density distributions relative to each other. The primary winding has higher density at its distal end, while the secondary winding has higher density at its distal end (which corresponds to the primary's endpoint). This asymmetric arrangement creates opposing capacitance effects that cancel out, while maintaining controlled leakage inductance.
3Measurement precision
If external matching inductors are added to compensate for leakage inductance variability, then circuit precision improves, but device complexity and cost increase
Solution Approach 1:
The transformer winding structure itself provides the leakage inductance compensation function that would otherwise require external components. By carefully designing the turn density distribution, the transformer achieves stable leakage inductance characteristics inherently, eliminating the need for external matching inductors and simplifying the overall circuit.
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
This design results in reduced noise and improved tolerance in leakage inductance, allowing for simplified circuits and potentially eliminating external matching inductors, thereby reducing costs and enhancing precision.
Implementation Method 1
a primary winding arranged around the first lengthwise region of the core portion... and a secondary winding arranged around the second lengthwise region of the core portion
Implementation Method 2
a first portion of a capacitor is formed in the primary winding by one turn from each layer directly facing the first lengthwise endpoint, and wherein a second portion of the capacitor is formed in the secondary winding by one turn from each layer directly facing the second lengthwise endpoint
Data Source
AI summary
Exemplarily, a transformer includes a primary winding with two layers and a secondary winding with two layers. One turn in each of the first and second layers of the primary winding face one turn in each of the first and second layers in the secondary winding. Spacing between adjacent turns in the primary winding is constant. Spacing between adjacent turns in the secondary winding is constant.