Wireless Charging Circuitry for Ferrite Saturation Mitigation

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Solution Overview

Problem

Wireless charging systems face challenges due to magnetic saturation in the wireless power receiving device, leading to reduced mated inductance and impaired charging performance, which can cause oscillations and communication failures.

Innovation Solution

Implementing saturation detection and mitigation techniques, including energy level measurements at sub-harmonic frequencies, adjusting phase and voltage of the AC drive signal, and using asymmetric switching schemes to manage magnetic saturation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If wireless power transmitting device operates at high power levels, then charging speed is improved, but magnetic saturation occurs causing reduced mated inductance and charging performance degradation

Engineering Contradiction:

Improvecharging speedVSAvoidcharging performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary saturation detection by measuring energy levels at sub-harmonic frequencies before saturation severely impacts charging performance. This early detection allows the control circuitry to adjust operating parameters proactively, preventing the contradiction from fully manifesting while maintaining high power levels for fast charging

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback monitoring of sub-harmonic energy levels to detect magnetic saturation conditions. When saturation is detected, the control circuitry adjusts the AC drive signal parameters (phase, voltage, frequency) to mitigate saturation effects, allowing the system to maintain high power operation while preventing performance degradation

Inventive Principle:

Principle #23Feedback

2Device complexity

If magnetic saturation is allowed to occur, then device complexity is reduced, but oscillations and communication failures occur

Engineering Contradiction:

Improvesystem complexityVSAvoidoperational stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system replaces complex mechanical or hardware-based saturation prevention mechanisms with a control-based approach using sub-harmonic energy measurement and software-controlled parameter adjustment. This substitution maintains operational stability while avoiding the need for additional complex hardware components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes operating parameters (phase, voltage, frequency of AC drive signal) based on detected saturation conditions to prevent oscillations and communication failures. This parameter adjustment approach maintains reliability without requiring additional complex hardware, resolving the contradiction between simplicity and stability

Inventive Principle:

Principle #35Parameter changes

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

Effectively mitigates magnetic saturation, stabilizing inductance and preventing oscillations, ensuring reliable wireless charging operations.

Implementation Method 1

magnetic saturation in the wireless power receiving device

Methodology Applied

Scientific EffectMagnetic saturation: Magnetic Saturation

Implementation Method 2

a coil that produces electromagnetic flux

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12456886B2Methods and circuitry for mitigating saturation in wireless power systems

Publication Date: 2025.10.28 APPLE INC

AI summary

A wireless charging system having a power transmitter may wirelessly transfer power to a power receiver. Shield saturation, such as saturation of a ferrite structure, in the wireless power receiver may occur under some operating conditions. Saturation can lead to disruptive oscillations in power transfer. The power transmitting may include control circuitry for detecting and mitigating saturation.