Convex Wireless Power Transmitter Surface for Foreign Object Rejection

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Solution Overview

Problem

Existing wireless power transfer systems face challenges in accurately detecting and rejecting foreign objects, leading to inefficiencies and safety hazards due to inaccuracy in power transfer measurements and potential overheating or fires, especially at higher power levels.

Innovation Solution

A wireless power transmitter design featuring a curved magnetic layer and coils with a convex outer surface that exploits gravity to repel foreign objects, combined with slots or holders for secure device positioning, ensuring safe and efficient power transfer by minimizing foreign object interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a flat or concave charging surface is used for wireless power transfer, then devices can be easily placed on the surface, but foreign objects can accumulate and cause safety hazards

Engineering Contradiction:

Improveease of device placementVSAvoidforeign object accumulation and overheating

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies a convex curved surface design to the wireless power transmitter charging surface. This curvature causes foreign objects placed on the surface to naturally roll off due to gravity, preventing accumulation and potential overheating. The curved surface maintains ease of device placement while actively rejecting foreign objects through its geometric shape.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If foreign object detection is implemented using power loss comparison, then safety can be improved, but the detection accuracy is insufficient leading to false positives or missed detections

Engineering Contradiction:

Improvesafety of wireless power transferVSAvoidaccuracy of foreign object detection

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the electrical measurement-based foreign object detection system with a mechanical/physical approach using a convex surface. Instead of relying on accurate power loss measurements to detect foreign objects, the system uses the physical shape of the charging surface to passively repel foreign objects through gravity, eliminating the need for complex detection algorithms and improving both safety and measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If higher power levels are used for wireless power transfer, then charging efficiency is improved, but the risk of foreign object overheating and fire increases

Engineering Contradiction:

Improvecharging efficiencyVSAvoidforeign object overheating and fire hazard

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary anti-action by designing the convex charging surface to proactively prevent foreign objects from remaining in contact with the high-power magnetic field source. Before foreign objects can overheat at high power levels, the curved surface geometry ensures they naturally roll off, providing preventive protection against overheating and fire hazards while maintaining high charging efficiency.

Inventive Principle:

Principle #9Preliminary anti-action

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 solution effectively prevents foreign objects from interfering with the charging process, ensuring accurate power transfer and safety by using gravity to repel objects and maintaining low magnetic field strength at peripheral regions, thus preventing overheating and enhancing user safety and efficiency.

Implementation Method 1

Faraday's law of magnetic induction provides that if a time-varying current is applied to one coil (e.g., a transmitter coil) a voltage will be induced in a nearby second coil (e.g., a receiver coil)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The convex outer surface of the wireless power transmitter exploits gravity to cause foreign objects to slide or roll away from the magnetic field generated by the transmitter

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 3

Certain metal objects such as coins, paper clips, and some jewelry can develop eddy currents in response to the varying magnetic field produced by the wireless power transmitter

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS10312745B2Wireless power transfer system with automatic foreign object rejection

Publication Date: 2019.06.04 CHARGEDGE INC

AI summary

In one embodiment, a wireless power transmitter comprises a transmitter coil structure comprising a magnetic layer having a geometric center line, the magnetic layer being curved symmetrically about a geometric center line, a first coil coupled to a second coil, the first coil and second coil wound in such a way that when a current flows in the first coil in a first spatial direction the current flows in the second coil in a second spatial direction, the first coil and the second coil disposed on the magnetic layer substantially symmetrically about the geometric center line of the magnetic layer, a power circuit configured to provide a time-varying current to the transmitter coil structure; and a housing including an outer surface having a convex shape, the transmitter coil structure being disposed underneath the outer surface of the housing. The convex outer surface of the wireless power transmitter exploits gravity to cause foreign objects to slide or roll away from the magnetic field generated by the transmitter.