Wireless Power Loss Estimation for Friendly Metal Heating

Solution Overview

Problem

Existing wireless power transfer systems face challenges in accurately estimating losses associated with 'friendly metal' structures, which can lead to inefficiencies and undesirable heating due to foreign objects, especially at higher power transfer levels.

Innovation Solution

A wireless power transmitter estimates friendly metal losses using a model based on rectifier voltage and current, with coefficients derived from regression analysis, and adjusts power transfer accordingly to mitigate these losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If wireless power transfer operates at higher power levels to enable faster charging, then charging speed is improved, but losses associated with friendly metal structures increase causing undesirable heating

Engineering Contradiction:

Improvecharging speedVSAvoidheating from friendly metal losses

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary characterization of friendly metal loss coefficients during manufacturing or initial pairing, storing these values for later use. This allows the system to have loss estimation data ready before actual power transfer begins, enabling faster charging at high power levels without unexpected heating issues.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors actual power transfer and compares it against estimated losses using the stored coefficients. This feedback mechanism allows the system to detect when actual losses deviate from expectations and adjust operation accordingly, preventing excessive heating while maintaining fast charging performance.

Inventive Principle:

Principle #23Feedback

2Power

If wireless power transfer operates at higher power levels, then power transfer rate is improved, but accuracy of loss estimation deteriorates leading to inefficiencies

Engineering Contradiction:

Improvepower transfer rateVSAvoidloss estimation accuracy

Core Design Contradiction:

PowerVSMeasurement precision

Solution Approach 1:

The system performs preliminary characterization of friendly metal loss coefficients during manufacturing or initial pairing, storing these values for later use. This allows the system to have loss estimation data ready before actual power transfer begins, enabling faster charging at high power levels without unexpected heating issues.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses different coefficients depending on the operating conditions and power level. By characterizing the system at multiple power levels and selecting appropriate coefficients, the system maintains accurate loss estimation even when operating at higher power transfer rates.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If traditional loss estimation methods are used, then device complexity is reduced, but productivity is worsened due to unnecessary power transfer interruptions

Engineering Contradiction:

Improveestimation system complexityVSAvoidpower transfer efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The system performs preliminary characterization of friendly metal loss coefficients during manufacturing or initial pairing, storing these values for later use. This allows the system to have loss estimation data ready before actual power transfer begins, enabling faster charging at high power levels without unexpected heating issues.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the stored coefficients to autonomously estimate losses and make decisions about power transfer without requiring complex real-time analysis or external intervention. This self-service approach maintains simple device architecture while improving productivity by avoiding unnecessary interruptions.

Inventive Principle:

Principle #25Self-service

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

Accurately estimates and mitigates friendly metal losses, improving efficiency and safety by reducing unnecessary power transfer interruptions and user interface issues at higher power levels.

Implementation Method 1

a wireless power transfer coil configured to magnetically couple to a wireless power transfer coil of a wireless power receiver to wirelessly transfer power

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20250330051A1Friendly metal loss estimation for wireless power transfer

Publication Date: 2025.10.23 APPLE INC

AI summary

A method for estimating friendly metal losses associated with wireless power transfer from a wireless power transmitter to a wireless power receiver can include obtaining an indication of received power including rectifier voltage and rectifier current of the wireless power receiver and computing a friendly metal power loss based on the indication of rectifier voltage and rectifier current of the wireless power receiver and one or more coefficients corresponding to a baseline wireless power transmission between the wireless power transmitter and the wireless power receiver. The rectifier voltage can be a rectifier output voltage, and the rectifier current can be a rectifier output current. Computing the friendly metal power loss can use an equation having a formPl⁢o⁢s⁢s=a·IT⁢X2+b·Irect2+c·Vrect2,where b is a coefficient relating to the rectifier current, c is a coefficient relating to the rectifier voltage, a is a coefficient relating to transmitter current ITX.