Interleaved Center-Tapped Transformer Structure for Lower AC Loss
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Solution Overview
Problem
Center tapped shell type transformers suffer from inefficient coupling between the primary winding and secondary windings, leading to large eddy current losses and poor current balance, which results in reduced efficiency due to the parallel structure of the secondary windings.
Innovation Solution
The transformer design involves winding a primary winding and two secondary windings in an interleaved alignment around a core, using Litz wire for all windings, and connecting them to a busbar and printed circuit board to enhance coupling and reduce coil losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a parallel structure is used in the secondary windings to decrease AC resistance loss, then the DC resistance is reduced, but the current balance becomes poor and AC loss remains very large
Solution Approach 1:
The secondary windings are divided into multiple individual windings (first secondary winding, second secondary winding, etc.) that are separately wound around the primary winding. Each secondary winding is further segmented into multiple parallel flat copper wires. This segmentation allows each winding to be independently optimized while maintaining overall current balance through the interleaved structure.
Solution Approach 2:
Different regions of the transformer are given different structures: the primary winding uses Litz wire for low AC resistance at high frequency, while the secondary windings use parallel flat copper wires for low DC resistance. The interleaved arrangement creates local optimization where each primary winding section is paired with appropriate secondary winding sections, improving current balance locally throughout the transformer.
2Adaptability or versatility
If only half of the primary winding is covered by a working secondary winding, then the transformer can provide center tap functionality, but the coupling between primary and secondary windings becomes inefficient causing large eddy current loss
Solution Approach 1:
The transformer structure transitions from a conventional single-layer arrangement to a multi-dimensional interleaved structure. Primary and secondary windings are arranged in alternating layers along the length of the core, creating a three-dimensional interleaved pattern. This dimensional change ensures that every section of the primary winding is covered by appropriate secondary windings, achieving full coupling while maintaining center tap functionality.
Solution Approach 2:
The windings are nested in an interleaved manner where primary and secondary windings are interlaced along the length of the core. Each primary winding section is nested with corresponding secondary winding sections, creating a tightly coupled structure where the windings are interpenetrating rather than separate. This nesting ensures maximum coupling efficiency while preserving the center tap configuration.
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 configuration improves the efficiency of the center tapped transformer by reducing eddy current losses and enhancing current balance, leading to lower AC resistance and increased coupling between the windings.
Implementation Method 1
The alternating current (AC) in the primary winding induces a varying magnetic flux in the transformer core. The primary and secondary windings are divided into subsections, where the low voltage winding and the high voltage winding subsections are alternatively placed on the center limb in the form of a sandwich.
Implementation Method 2
The use of a single thick copper sheet or wire or the use of many thin copper sheets or wires in parallel only reduces the direct current (DC) resistance of the secondary windings, but provides very limited reduction in the AC resistance, so the AC loss of the copper sheet(s) or wire(s) is still very large.
Data Source
AI summary
Devices and methods for coupling an interleaved aligned first and second secondary windings coil structure with a primary winding of a center tapped transformer are provided. In particular, a method for forming a center tapped transformer includes forming a winding core, winding a primary winding around the winding core and winding a first secondary winding and a second secondary winding in an interleaved alignment around the primary winding.