Planar Transformer Winding Loss Reduction via Core Recess Design
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Solution Overview
Problem
Planar transformers in power conversion circuits face significant winding losses due to air gap fringing magnetic flux, which affect efficiency and size, as existing designs do not effectively optimize the keep-away distance and recess shapes in magnetic cores.
Innovation Solution
The design incorporates a first magnetic core in contact with a second core, with primary windings between secondary windings, and a recessed region in the second core, optimizing the ratio of keep-away distance to air gap thickness and recess depth to reduce winding losses, using E- and I-core configurations with specific recess shapes like rectangles, trapezoids, and arc-trapezoids to minimize magnetic field intensity and flux fringing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the air gap between magnetic cores is reduced to decrease transformer size, then the transformer volume decreases, but winding losses increase due to magnetic flux fringing
Solution Approach 1:
The patent extracts the problematic fringing flux from the winding area by introducing a recess in the magnetic core. The recess creates an air gap that directs the fringing flux away from the windings, allowing the transformer to maintain a compact size while reducing winding losses caused by magnetic flux interference.
Solution Approach 2:
The patent applies local quality by creating a recess specifically in the region where fringing flux interacts with windings. This localized structural modification optimizes the magnetic field distribution in the critical area without changing the overall transformer design, thereby reducing winding losses while maintaining compact dimensions.
2Loss of energy
If the keep-away distance between windings and air gap is increased to reduce winding losses, then winding losses decrease, but the transformer size increases
Solution Approach 1:
The patent resolves the contradiction by transitioning from a one-dimensional solution (increasing keep-away distance) to a two-dimensional solution (introducing a recess). The recess creates a new spatial dimension that allows the fringing flux to be directed away from the windings without increasing the overall transformer footprint, thus reducing winding losses while maintaining compact size.
3Loss of energy
If recess depth is increased to reduce magnetic flux fringing, then winding losses decrease, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the recess depth as a critical parameter to balance performance and manufacturability. By carefully selecting the recess depth within a specific range, the design achieves effective reduction of magnetic flux fringing and winding losses while maintaining feasibility for standard manufacturing processes, thus resolving the contradiction between performance improvement and manufacturing ease.
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 approach significantly reduces winding losses by optimizing the keep-away distance and recess shapes, enhancing the efficiency of power conversion circuits and minimizing magnetic flux fringing, thereby improving overall transformer performance.
Implementation Method 1
a first magnetic core having a first portion in contact with a second magnetic core and a second portion separated from the second magnetic core by a distance d, a plurality of primary windings formed around the second portion, a first secondary winding forming a first layer
Data Source
AI summary
Systems and methods for improving winding losses in transformers. In one aspect, a transformer includes a first magnetic core having a first portion in contact with a second magnetic core and a second portion separated from the second magnetic core by a distance d, a plurality of primary windings formed around the second portion, a first secondary winding forming a first layer having a first inner diameter, a second secondary winding forming an nth layer having a second inner diameter. The plurality of primary windings are positioned between the first layer and the nth layer, where the plurality of primary windings, and the first secondary winding and the second secondary winding are formed around the second portion, and a difference between the first inner diameter and the second inner diameter defines a distance y, and a ratio of distance y to distance d is between 0.01 to 10.