Split-Inductor Dual Active Bridge for Transformer Current Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-frequency transformers used in applications like EV fast charging and renewable energy systems face significant losses due to circulating currents in parallel conductors, which reduce transformer performance and increase costs, and existing solutions require additional components and manufacturing effort.
Innovation Solution
A dual active bridge DC/DC converter design that splits energy transfer inductors between parallel transformer windings, preventing circulating currents and allowing for efficient operation without extra components or resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If litz wire is used to reduce high-frequency losses in transformer coils, then winding losses are reduced, but the cost increases significantly and manufacturing complexity increases
Solution Approach 1:
The patent segments the transformer windings into multiple parallel conductors with individually optimized dimensions. Each conductor is designed with specific height and width parameters to minimize skin and proximity effects at high frequencies, replacing the need for complex litz wire structures while maintaining low winding losses
Solution Approach 2:
The patent applies local quality optimization by designing each parallel conductor with locally optimized dimensions (height h and width b) based on its specific position and electromagnetic environment. This allows each conductor to be tailored for minimal losses at high frequencies without requiring uniform complex structures throughout
2Power
If parallel conductors are used to handle high currents above 100 A, then current handling capacity is increased, but circulating currents are induced due to stray fields which significantly increase losses
Solution Approach 1:
The patent applies equipotentiality by carefully designing the magnetic circuit and yoke structure to ensure uniform magnetic potential distribution across parallel conductors. This minimizes potential differences between conductors that would otherwise drive circulating currents, while still allowing high current handling capacity
Solution Approach 2:
The patent uses asymmetric positioning and dimensioning of parallel conductors relative to the magnetic core to minimize stray field exposure. By optimizing the spatial arrangement and individual conductor dimensions, the design reduces asymmetric magnetic coupling that would induce circulating currents between parallel conductors
3Device complexity
If aluminium foil windings are used to reduce cost, then manufacturing cost is reduced, but winding losses increase significantly at high frequencies due to skin and proximity effects
Solution Approach 1:
The patent segments the winding into multiple thin parallel aluminium foil conductors rather than using a single thick foil. This segmentation reduces the effective thickness of each conductor, minimizing skin effect losses at high frequencies while maintaining the cost advantages of aluminium foil construction
Solution Approach 2:
The patent optimizes the local dimensions (height and width) of each aluminium foil conductor to achieve optimal performance at high frequencies. By carefully controlling the local geometry of each foil segment, the design minimizes proximity effects and skin effects while maintaining manufacturing simplicity and cost-effectiveness
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 design enhances the maximum current handling capacity of transformers, reduces losses, and lowers costs by eliminating circulating currents, enabling more efficient and cost-effective high-power transformer construction.
Implementation Method 1
a first plurality of M energy transfer inductors; wherein for each of the M primary windings, a different one from the first plurality of energy transfer inductors is connected between said primary winding bridge and the converter bridge
Implementation Method 2
a transformer, preferably a medium frequency transformer, having a primary side and a secondary side; the primary side of the transformer comprising a plurality of M>1 primary windings
Data Source
AI summary
A dual active bridge DC/DC converter in accordance with the invention comprises a first DC link, preferably comprising a first DC link capacitor; a converter bridge connected to the first DC link; a transformer, preferably a medium frequency transformer, having a primary side and a secondary side; the primary side of the transformer comprising a plurality of M>1 primary windings, each of the plurality of primary windings having a first and a second terminal; wherein the dual active bridge DC/DC converter further comprises a first plurality of M energy transfer inductors; and wherein for each of the M primary windings, a different one from the first plurality of energy transfer inductors is connected between said primary winding bridge and the converter bridge.