PCB Planar Transformer Stacking for Balanced Magnetomotive Force
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Solution Overview
Problem
Conventional resonant converters are bulky due to their transformer structure, leading to poor power density and increased line losses, as the magnetomotive force is biased, causing heat dissipation issues.
Innovation Solution
A planar transformer with a specific stacked structure is implemented, where primary-side and secondary-side traces on a circuit board generate balanced magnetic fluxes using an iron core, maintaining magnetomotive force balance and reducing size and heat concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional transformer structure with wound coils and iron cores is used, then magnetic circuit is formed, but the size becomes bulky and power density decreases
Solution Approach 1:
The patent replaces the conventional mechanical winding structure with planar printed circuit board traces to form the transformer coils. This substitution eliminates the need for manual wire winding and traditional iron core assemblies, significantly reducing the transformer's volume while maintaining its electromagnetic functionality. The planar structure allows for compact integration and improved power density.
Solution Approach 2:
The patent transitions from three-dimensional wound coil structures to two-dimensional planar traces on a circuit board. This dimensional reduction enables more compact packaging and reduces the overall transformer volume, directly addressing the contradiction between size reduction and power density maintenance.
2Loss of energy
If conventional coil winding structure is used, then transformer function is achieved, but magnetomotive force becomes biased causing increased line losses
Solution Approach 1:
The patent employs asymmetric placement of primary and secondary traces relative to the magnetic core, specifically positioning them at different distances from the core. This asymmetric configuration is deliberately designed to balance the magnetomotive force by compensating for the different number of turns in primary and secondary windings, thereby reducing magnetomotive force bias and associated line losses.
Solution Approach 2:
The patent applies different trace configurations at different locations around the magnetic core. By varying the trace width, spacing, or number of turns in specific regions, the design optimizes the magnetic flux distribution and achieves magnetomotive force balance, reducing energy losses without requiring uniform structure throughout.
3Temperature
If conventional transformer structure is used, then transformation function is provided, but heat dissipation becomes difficult due to concentrated heat generation
Solution Approach 1:
The patent divides the transformer into separate functional layers on the circuit board, with primary traces, secondary traces, and magnetic core positioned on different planes. This segmentation allows for better thermal management by distributing heat generation across multiple layers and improving heat dissipation pathways, preventing localized heat concentration.
Solution Approach 2:
By transitioning to a planar multi-layer structure, the patent increases the surface area available for heat dissipation and creates thermal pathways through the circuit board substrate. This dimensional change from compact 3D winding to spread-out 2D planar structure improves thermal management and reduces heat concentration.
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 planar transformer achieves reduced size, increased power density, and improved heat dissipation by balancing magnetomotive force, reducing AC impedance and line losses, and enhancing efficiency.
Implementation Method 1
the primary-side traces respectively generate a first direction magnetic flux
Implementation Method 2
the secondary-side traces respectively generate a second direction magnetic flux
Implementation Method 3
The primary-side traces and the secondary-side traces are configured in a specific stacked structure to maintain the first direction magnetic flux and the second direction magnetic flux within a specific range formed by a magnetic flux origin and a first predetermined offset and a second predetermined offset, so that a magnetomotive force of the planar transformer remains balanced
Data Source
AI summary
A planar transformer is configured on a multi-layer circuit board of a resonant converter. The planar transformer includes multiple layers of primary-side traces, multiple layers of secondary-side traces, and an iron core. The primary-side traces serve as a primary-side coil of the transformer to generate a first direction magnetic flux when the resonant converter operates. The secondary-side traces serve as a secondary-side coil of the transformer to generate a second direction magnetic flux when the resonant converter operates. The primary-side traces and the secondary-side traces surround a first core pillar and the second core pillar, and the primary-side traces and the secondary-side traces are configured in a specific stacked structure on the multi-layer circuit board, so that a magnetomotive force of the planar transformer can maintain balance during the operation of the resonant converter.