Rectangular Magnetic Flux Pad for Inductive EV Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional inductive power transfer systems for electric vehicle charging face challenges with power transfer efficiency due to separation distance sensitivity, leading to reduced power transfer at larger distances and potential overloading at closer distances, requiring precise alignment and height adjustments, which complicates the charging process and reliability.
Innovation Solution
A magnetic flux pad design featuring two pole areas with a magnetically permeable core and flat coils arranged to form a flux pipe, directing magnetic flux arch-shapedly beyond the pad's surface, minimizing leakage flux and allowing efficient power transfer over a wider range of distances with reduced sensitivity to misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional circular power pads are used for inductive charging, then power transfer can be achieved, but the system requires precise alignment (within 50 mm) and controlled separation distance, reducing ease of operation
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 source, and their combined effect creates a larger effective coupling area. This segmentation allows the system to maintain reliable power transfer even when alignment is not perfect, as multiple segments can contribute to the magnetic coupling
Solution Approach 2:
The patent transitions from circular pads to rectangular segments with specific dimensional ratios (length to width approximately 2:1). This dimensional change creates an elongated flux path that extends further in one direction, effectively increasing the coupling area and tolerance in the direction perpendicular to the long axis of the rectangles
2Ease of operation
If separation distance between power pads is increased to accommodate vehicle ground clearance, then ease of operation improves, but power transfer efficiency decreases due to reduced mutual inductance
Solution Approach 1:
The patent uses ferrite bars positioned beneath each rectangular segment to pre-concentrate and guide the magnetic flux before it reaches the air gap between pads. This preliminary flux concentration action maintains higher flux density at the separation interface, compensating for the reduced coupling effect of increased distance
Solution Approach 2:
The patent employs ferrite material with high magnetic permeability as a composite element between the copper windings and the air gap. This composite structure creates a flux pipe that channels magnetic flux efficiently across the separation distance, maintaining power transfer capability even when ground clearance requires larger pad separation
3Power
If separation distance is reduced to increase power transfer, then power capability improves, but the system becomes inoperable below 50 mm due to excessive power and circuit overloading
Solution Approach 1:
The patent creates localized flux concentration regions at each rectangular segment using ferrite bars, rather than having a uniform flux distribution across the entire pad area. This local quality control allows power to be distributed across multiple independent flux paths, preventing any single region from generating excessive power that could overload the circuit
4Power
If induced voltage in the pick-up pad is made separation sensitive to match mutual inductance variation, then power transfer efficiency improves, but the system requires frequent tuning and adjustment, increasing device complexity
Solution Approach 1:
The patent changes the geometric parameters of the flux pipe structure (rectangular segment dimensions, ferrite bar positioning) to inherently maintain more stable inductance characteristics over the separation distance range. This parameter optimization reduces the rate of change of mutual inductance with distance, decreasing the need for frequent electronic tuning
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 by maintaining high flux concentration over a significant distance, reducing the need for precise alignment and minimizing leakage flux, thus enabling reliable and efficient charging of electric vehicles across a broader separation range.
Implementation Method 1
Inductive power transfer apparatus comprising two pole areas for receiving or sending flux, a magnetically permeable core, two coils magnetically associated with the core
Implementation Method 2
a magnetically permeable core, whereby the flux enters the pad at one of the pole areas and exits the pad at the other pole area
Data Source
AI summary
A magnetic flux pad for receiving or generating magnetic flux. The pad includes two pole areas (11, 12) associated with a magnetically permeable core 14. Coils 17 define the pole areas. The pad allows useable flux to be generated at a significant height above a surface of the pad.