PCB Planar Transformer With Ceramic Isolation and Embedded Cooling
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Solution Overview
Problem
Medium voltage AC to DC converters in electric vehicle charging stations face challenges such as high eddy current and AC losses, high voltage isolation requirements, parasitic resistances and capacitances, and cooling issues, which affect efficiency and reliability.
Innovation Solution
A high-frequency planar transformer construction using printed circuit boards (PCBs) with ceramic insulation, embedded cooling tubes, and a magnetic core, along with dual active bridge modules to manage power transfer and isolation, reducing parasitics and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LITZ wire is used to reduce eddy current losses, then conductor performance improves, but cost and insulation space increase
Solution Approach 1:
The patent extracts the insulation function from traditional LITZ wire construction by using a planar transformer design where the PCB substrate itself provides the insulation, eliminating the need for individual strand insulation while maintaining low eddy current losses through the planar winding geometry
Solution Approach 2:
The patent replaces the mechanical LITZ wire structure with a planar PCB-based winding system, substituting the need for fine insulated strands with a solid copper trace pattern on an insulating PCB substrate, thereby reducing insulation material while maintaining electrical performance
2Reliability
If high voltage isolation is implemented with large creepage and clearance distances, then isolation reliability improves, but device size increases
Solution Approach 1:
The patent uses ceramic insulation material with high dielectric strength to achieve the required 30-50 kV isolation in a compact space, replacing traditional air or polymer insulation that would require much larger creepage and clearance distances
Solution Approach 2:
The patent changes the insulation material parameter from conventional materials to high-dielectric-strength ceramic, enabling reduced physical dimensions while maintaining the same voltage isolation capability
3Temperature
If liquid cooling is implemented, then cooling efficiency improves, but eddy current losses in cooling components increase
Solution Approach 1:
The patent extracts the cooling function from traditional external cooling systems and integrates it directly into the transformer core structure, eliminating separate cooling components that would generate eddy current losses
Solution Approach 2:
The patent merges the cooling channels with the magnetic core structure, combining the structural support function with the thermal management function in a single integrated component
4Manufacturing precision
If planar PCB windings are used, then manufacturing precision and consistency improve, but parasitic capacitance increases
Solution Approach 1:
The patent applies different trace geometries and spacing in different regions of the PCB winding to optimize the balance between manufacturing precision and parasitic capacitance, using local variations in trace width and spacing to control electrical characteristics
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 solution provides a compact, efficient, and reliable power transfer system with reduced losses and improved isolation, suitable for high-power medium-voltage applications.
Implementation Method 1
A magnetic core extends entirely around the windings and the electrical insulator
Implementation Method 2
A ceramic electrical insulator electrically separates the primary and secondary windings
Implementation Method 3
an embedded cooling tube
Data Source
AI summary
A planar transformer includes a primary winding having one or more PCBs each including metallic traces. A secondary winding includes one or more PCBs having metallic traces. A ceramic electrical insulator electrically separates the primary and secondary windings. A magnetic core extends entirely around the windings and the electrical insulator.