Planar PCB Transformer Layout for Isolation and Cooling in DABs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 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 inefficiencies in planar transformers, which affect efficiency and reliability.
Innovation Solution
A planar transformer design using magnetic cores, printed circuit boards with metallic traces, ceramic insulation, and embedded cooling tubes, along with a dual active bridge module to manage power transfer and cooling, minimizing parasitics and enhancing isolation and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LITZ wire is used to reduce eddy current losses, then conductor losses are reduced, but winding space is occupied by insulation and cost increases
Solution Approach 1:
The patent replaces traditional LITZ wire construction with planar PCB-based windings. The PCB traces are formed by etching copper patterns on insulated substrates, eliminating the need for bundled insulated strands. This substitution reduces insulation space occupation while maintaining low eddy current losses through the planar geometry and controlled trace dimensions.
Solution Approach 2:
The patent changes the physical parameters of the conductor by using thin copper traces on PCBs instead of thick LITZ wire bundles. The trace thickness and width are optimized to achieve low resistance while the planar layout reduces eddy current effects. This parameter change allows efficient current conduction without requiring excessive insulation space.
2Reliability
If high voltage isolation is implemented using traditional methods, then isolation requirements are met, but creepage and clearance distances become very large
Solution Approach 1:
The patent uses composite insulation structures combining multiple materials with different properties. The PCB itself provides base insulation, while additional conformal coating layers and potting compounds are applied to enhance dielectric strength. This multi-material approach achieves high voltage isolation (30-50 kV) in a compact footprint by leveraging the synergistic effects of different insulating materials.
Solution Approach 2:
The patent transitions from two-dimensional isolation planning to three-dimensional isolation architecture. Multiple insulation layers are stacked vertically between primary and secondary windings, and ground walls are positioned at strategic three-dimensional locations. This 3D isolation strategy achieves required creepage and clearance distances without expanding the planar footprint of the transformer.
3Temperature
If liquid cooling is employed to remove heat, then cooling efficiency is improved, but eddy current losses increase due to conductive metal placement
Solution Approach 1:
The patent introduces electrically insulating thermal interface materials and non-conductive cooling channels as intermediaries between the heat-generating components and the cooling system. The PCB substrates themselves serve as thermal pathways with embedded non-conductive cooling channels, allowing efficient heat transfer to coolant while preventing eddy current formation. This intermediary approach decouples the thermal conduction path from the electrical conduction path.
4Productivity
If parasitic resistances and capacitances are minimized for high-frequency switching, then switching efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the winding structure with the PCB substrate to eliminate separate winding forms and associated parasitics. The copper traces are directly formed on the PCB layers, creating integrated current paths that minimize loop areas and reduce parasitic inductance. This merging of winding and substrate functions reduces the number of discrete components and interconnections, thereby lowering overall parasitic effects while maintaining manageable device complexity.
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 design achieves efficient power transfer with reduced losses, improved cooling, and high isolation, enabling compact and reliable 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 could also be a heat pipe
Implementation Method 4
Due to this construction, however, the eddy current and AC losses can be high. As a result, the conductors in the transformer tend to be made from LITZ wire, laminated tape or arranged in a planar transformer
Implementation Method 5
While some inductance is necessary for Zero Voltage Switching (ZVS) operation
Data Source
AI summary
A voltage converter circuit includes a plurality of dual active bridges (DABs). Each DAB has a first stage with a plurality of first switches, a second stage with a plurality of second switches, and a transformer having a first winding coupled to a least one of the first switches and a second winding coupled to at least one of the second switches. At least one of the first and second stages of a plurality of the DABs that is a proper subset of the DABs are arranged in parallel with respect to the first winding of the transformer in each of the respective plurality of the DABs, with the parallel first stages of the plurality of the DABs being arranged in series with respect to the first winding of the transformer of at least one other DAB of the DABs, or at least one of the first and second stages of a plurality of the DABs that is a proper subset of the DABs are arranged in series with respect to the second winding of the transformer in each of the respective plurality of the DABs, with the series second stages of the plurality of the DABs being arranged in parallel with respect to the second winding of the transformer of at least one other DAB of the DABs.