Multi-Coil Flux Pad for Inductive Power Transfer
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Solution Overview
Problem
Inductive power transfer systems face challenges in efficiently transferring power over varying distances and displacements, particularly in applications like electric vehicle charging, where magnetic field leakage and mismatched pad designs limit power transfer efficiency and compliance with regulatory limits.
Innovation Solution
A magnetic flux pad with at least three overlapping coils positioned in the same plane, with selective energization capabilities and a ferrite arrangement to minimize mutual coupling, allowing for a sliding time-varying magnetic field and improved power transfer flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil pad is used for inductive power transfer, then the structure is simple, but power transfer efficiency decreases when vehicle ground clearance or lateral displacement varies
Solution Approach 1:
The single coil pad is segmented into multiple independent coils (typically three coils arranged in a triangular pattern). Each coil can be independently controlled and contributes to the overall magnetic field. This segmentation allows the system to maintain effective coupling with the vehicle's pickup coil even when ground clearance or lateral displacement varies, as at least one coil will remain optimally positioned relative to the pickup coil.
Solution Approach 2:
The patent implements dynamic control of the multiple coils through selective energization and phase adjustment. The controller can dynamically adjust which coils are active and their respective phase angles based on detected vehicle position and ground clearance. This dynamic adaptation optimizes power transfer efficiency across varying operational conditions without requiring a complex mechanical adjustment mechanism.
2Loss of energy
If multiple coils are used to improve power transfer adaptability, then power transfer efficiency increases, but magnetic field leakage increases
Solution Approach 1:
The patent applies local quality by creating concentrated magnetic field regions around each individual coil rather than a single diffuse field. Each coil generates a localized magnetic flux that is confined to its immediate vicinity and the vehicle's pickup coil. This localized field generation reduces electromagnetic interference and magnetic field leakage to surrounding areas while maintaining high power transfer efficiency between the transmitter and receiver coils.
Solution Approach 2:
The patent converts the potential harmful effect of multiple magnetic fields into a beneficial arrangement through phase control. By adjusting the phase angles of the multiple coils, the system creates a constructive interference pattern that concentrates magnetic flux in the desired direction (toward the vehicle's pickup coil) while destructive interference reduces field leakage in other directions. This transforms what could be harmful electromagnetic radiation into a controlled and beneficial magnetic flux distribution.
3Adaptability or versatility
If coils are positioned to cover wide area for vehicle alignment tolerance, then adaptability improves, but mutual coupling between coils increases
Solution Approach 1:
The patent employs asymmetric coil positioning and sizing to optimize the magnetic field distribution. The coils are arranged in a triangular pattern with specific spacing and orientation that creates an asymmetric but balanced field coverage. This asymmetric arrangement provides wide area coverage for vehicle alignment tolerance while the specific geometric configuration minimizes mutual coupling between adjacent coils by positioning them at optimal distances and angles.
Solution Approach 2:
The patent utilizes parameter changes in the form of adjustable phase angles and current magnitudes for each coil. By independently controlling the electrical parameters of each coil, the system can optimize the magnetic field distribution to achieve wide area coverage while minimizing mutual coupling effects. The controller adjusts these parameters dynamically based on vehicle position detection, maintaining optimal performance across various alignment conditions.
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
Enhances power transfer efficiency and adaptability across different vehicle ground clearances and orientations, reducing magnetic field leakage while maintaining regulatory compliance through decoupled coils and adjustable phase currents.
Implementation Method 1
a magnetic flux pad for generating or receiving magnetic flux, the pad comprising: a magnetically permeable core, and at least three overlapping coils magnetically associated with the core
Implementation Method 2
a magnetically permeable core, and at least three overlapping coils magnetically associated with the core
Data Source
AI summary
The present invention provides a multi-coil inductive power transfer primary comprising a plurality of coil. A power transfer regime is selected based on a determined load on each of the plurality of coils.