Segmented Magnetic Flux Pad for EV Inductive Charging
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Solution Overview
Problem
Conventional inductive power transfer (IPT) systems face challenges in efficiently charging electric vehicles due to separation sensitivity, leading to reduced power transfer at varying distances, component overload, and frequency mismatch, limiting the operational range to 40-100 mm, which is impractical for vehicles with higher ground clearance.
Innovation Solution
A magnetic flux pad design incorporating a 'flux pipe' with a ferrite core and aluminum plates to control leakage flux, featuring a toroidal winding arrangement with multiple coils connected magnetically in series and electrically in parallel, which directs flux efficiently and maintains consistent power transfer across different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional circular power pads are used for inductive power transfer, then power can be transferred at distances up to 100 mm, but the coupling factor becomes so small that practical power transfer becomes impractical and the system requires very precise alignment (within 50 mm)
Solution Approach 1:
The patent divides the conventional circular power pad into multiple rectangular segments arranged in a grid pattern. Each segment acts as an independent flux path, allowing the system to maintain stronger coupling at greater separations by utilizing multiple distributed flux paths rather than relying on a single large circular pad.
Solution Approach 2:
The patent transitions from circular geometry to rectangular segments with specific aspect ratios, optimizing the dimensional configuration to enhance flux coupling. The rectangular shape with dimensions approximately 2:1 or 3:1 provides better flux concentration and coupling characteristics compared to the conventional circular design.
2Power
If the separation between power pads is reduced to increase power transfer, then more power can be transferred, but the induced voltage becomes so high that circuit components become overloaded and the system must be shut down
Solution Approach 1:
By dividing the power transfer into multiple independent rectangular segments, the system distributes the flux density and induced voltage across multiple paths. This segmentation prevents excessive voltage concentration in any single location, allowing higher total power transfer without overloading individual circuit components.
Solution Approach 2:
The patent applies different characteristics to different segments of the power pad, with each rectangular segment optimized for specific flux patterns. This local optimization ensures that no single segment experiences excessive flux density that would lead to component overload, while the aggregate system achieves high power transfer capability.
3Adaptability or versatility
If the separation between power pads varies, then the system must operate within a narrow range of 40-100 mm, but this limits adaptability to vehicles with different ground clearances
Solution Approach 1:
The segmented rectangular configuration creates multiple independent flux paths that maintain consistent coupling characteristics across a broader range of separations. Each segment contributes to the overall power transfer, providing redundancy and consistency whether the separation is 40 mm or 100 mm, thereby expanding the reliable operational range.
Solution Approach 2:
The patent optimizes the rectangular segment dimensions and arrangement to achieve parameter values that maintain stable coupling factor across varying separations. By carefully selecting the aspect ratio and spacing of rectangular segments, the system achieves parameter insensitivity that allows consistent operation from 40 mm to 100 mm separation distances.
4Length of stationary object
If conventional circular power pads are used, then the structure is simple, but the flux pattern creates horizontal flux lines that do not extend far beyond the pad center, limiting effective separation distance
Solution Approach 1:
The patent replaces the conventional circular pad with multiple rectangular segments arranged in a grid. This segmentation creates vertical flux paths that extend further beyond the pad boundaries compared to horizontal flux in circular pads, effectively increasing the flux extension distance and enabling greater separation between primary and secondary pads.
Solution Approach 2:
The rectangular segment configuration fundamentally changes the flux pattern orientation and extension characteristics. Instead of horizontal flux lines confined near the center, the rectangular geometry generates flux patterns that extend vertically and laterally to greater distances, expanding the effective operational envelope.
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 enhances power transfer efficiency and reliability by maintaining consistent induced voltage and uncompensated power across varying frequencies, allowing operation over a broader separation range and reducing power loss, thus enabling effective charging of electric vehicles with higher ground clearance.
Implementation Method 1
a coil wound about the core
Implementation Method 2
a magnetically permeable core magnetically connecting the pole areas
Implementation Method 3
aluminum plates to control leakage flux
Data Source
Figure 1~2
Figure 3~4
Figure 4A~5
AI summary
A magnetic flux pad for generating or receiving magnetic flux has two pole areas (11, 12), a permeable core (14) and a coil (16) wound about the core. The pad allows useable flux to be generated at a significant height above a surface of the pad.