Overlapping Flat Coils for Wireless Power Transfer Flux Control

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Solution Overview

Problem

Existing inductive power transfer (IPT) systems face challenges in reducing leakage magnetic flux and achieving efficient power transfer, particularly in electric vehicle charging applications where magnetic coupling structures are misaligned, leading to increased mutual coupling between coils and inefficiencies.

Innovation Solution

The design incorporates a magnetic coupling structure with flat coils having overlap and non-overlap portions, where the overlap portions have minimal mutual coupling and a magnetically permeable material directing magnetic flux away from non-overlap areas, along with methods to detect and adjust mutual coupling for optimal power transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If coils are placed close together to maximize power transfer area, then power transfer capability is improved, but mutual coupling between coils increases causing interference and reduced efficiency

Engineering Contradiction:

Improvepower transfer capabilityVSAvoidmutual coupling loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The magnetic coupling structure is divided into multiple flat coils with distinct overlap and non-overlap portions. Each coil is segmented to have specific spatial relationships with adjacent coils, creating controlled magnetic field zones that minimize mutual coupling while maintaining power transfer capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the coils have different properties: the overlap portions are designed with minimal mutual coupling characteristics, while the non-overlap portions can have denser turn spacing to enhance local magnetic field strength for power transfer without interfering with adjacent coils.

Inventive Principle:

Principle #3Local quality

2Productivity

If coil turn spacing is reduced to increase magnetic field strength, then power transfer efficiency is improved, but leakage flux increases exceeding safety guidelines

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidleakage magnetic flux

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The coil structure implements non-uniform turn spacing where different regions have different spacing characteristics. The overlap portions have spacing optimized to minimize leakage flux, while non-overlap portions can have tighter spacing to maintain magnetic field strength for efficient power transfer.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the potentially harmful leakage flux into beneficial controlled magnetic coupling by designing the overlap portions to have minimal mutual coupling. This controlled configuration ensures that magnetic flux is directed where needed for power transfer while preventing excessive leakage beyond safety guidelines.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If magnetic coupling structures are misaligned during EV charging, then ease of operation is improved, but power transfer efficiency decreases due to increased mutual coupling

Engineering Contradiction:

Improvealignment toleranceVSAvoidpower transfer efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The magnetic coupling structure with multiple flat coils provides multiple functional zones that can adapt to different alignment conditions. The overlap and non-overlap portions work together to maintain effective power transfer across a range of misalignment scenarios, making the system universally effective regardless of precise positioning.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically adapts to misalignment through its multi-coil configuration where different coils can be selectively energized or where current distribution can be adjusted based on the actual alignment state, maintaining optimal power transfer efficiency under varying operational conditions.

Inventive Principle:

Principle #15Dynamics

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 approach minimizes leakage flux and maximizes power transfer efficiency by optimizing coil spacing and permeable material placement, allowing for independent energization of coils and improved alignment tolerance, thereby reducing the VA requirement and enhancing overall system performance.

Implementation Method 1

a magnetically permeable material directing magnetic flux away from non-overlap areas

Methodology Applied

Scientific EffectMagnetic flux direction control: Magnetic Field

Implementation Method 2

magnetic coupling structure with flat coils having overlap and non-overlap portions

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10958111B2Power transfer and leakage flux control

Publication Date: 2021.03.23 AUCKLAND UNISERVICES LTD

AI summary

Magnetic coupling structures for wireless power transfer include overlapping coils which are configured to provide improved flux patterns. Control methods are used to determine the variation in coupling factor relative to alignment between the primary magnetic coupling structures and energise one or more coils of the primary magnetic coupling structure dependent on the relative alignment of the coupling structures to maximise coupling.