Electromagnet Control for Wireless Charging Stability

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Solution Overview

Problem

Magnetic attraction in wireless charging technologies can interfere with the normal operation of medical devices such as pacemakers, cochlear implants, and defibrillators, posing safety risks due to the magnetic fields used for charging stability.

Innovation Solution

A wireless charging method that uses identification information to control the power state of an electromagnet in a mobile terminal, ensuring it is only activated when a charging condition is met, thereby avoiding unnecessary magnetic interference by powering off when not in use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If magnets are used for magnetic attraction fixation in wireless charging, then the position stability between mobile terminal and charging equipment is improved, but harmful magnetic fields are generated that can interfere with medical devices such as pacemakers and defibrillators

Engineering Contradiction:
Improveposition stabilityVSAvoidmagnetic field interference
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent uses an electromagnet instead of a permanent magnet, allowing the magnetic field to be dynamically controlled. The electromagnet is powered on only when charging conditions are met (when the mobile terminal is properly positioned on the charging equipment) and powered off otherwise, making the magnetic field dynamic rather than static. This resolves the contradiction by providing position stability during charging while eliminating harmful magnetic field interference during non-charging periods.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the state parameter of the magnet from permanent (always magnetic) to controllable (magnetic only when powered). By controlling the power state of the electromagnet based on charging conditions, the magnetic field strength transitions from zero to active level and back to zero, optimizing both position stability during charging and safety during non-charging states.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the electromagnet is always powered on to ensure charging stability, then position fixation is maintained, but energy consumption increases and unnecessary magnetic interference occurs

Engineering Contradiction:
Improvecharging stabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The electromagnet operates periodically rather than continuously - it is powered on only during the charging period when needed for position fixation and powered off during non-charging periods. This periodic operation maintains charging stability when required while significantly reducing energy consumption and eliminating unnecessary magnetic interference during off periods.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent extracts the magnetic attraction function from a permanent magnet and relocates it to an electromagnet that can be selectively activated. This allows the magnetic field to be 'taken out' or removed when not needed, eliminating continuous energy consumption and unnecessary magnetic interference while maintaining reliability during charging operations.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enhances the stability and security of wireless charging by ensuring the electromagnet is only active during charging, minimizing interference with other medical devices and improving overall safety.

Implementation Method 1

controlling an electromagnet body in the mobile terminal to be powered on, such that the mobile terminal is attracted to the charging device

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

the distance is sensed by a Hall sensor in the mobile terminal and a Hall sensor in the charging device

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP4050759A1Wireless charging method, electronic device and mobile terminal
Publication Date: 2022.08.31 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4050759A1 patent drawingFigure 1
  • EP4050759A1 patent drawingFigure 2
  • EP4050759A1 patent drawingFigure 3

AI summary

The present disclosure relates to a wireless charging method, an electronic device and a mobile terminal. The wireless charging method includes: acquiring (S101) identification information of a charging device, wherein the identification information is configured to indicate a position state between the mobile terminal and the charging device; in response to determining that the identification information meets a preset charging condition, controlling (S102) an electromagnet body in the mobile terminal to be powered on to attract the charging device; and when the identification information does not meet the preset charging condition, controlling (S103) the electromagnet body in the mobile terminal to be powered off. The mobile terminal powers on the electromagnet body only when charging, to make it be in a magnetic state; and after the charging is completed, powers off it to make it be in a non-magnetic state. In this way, it can not only ensure the position stability and charging stability of the mobile terminal and the charging equipment when charging, but also avoid affecting the normal operation of other equipment in the environment, especially the normal operation of pacemakers, cochlear implants, hearing aids, and defibrillators in the human body, during normal use of the mobile terminal, thus the security of the mobile terminal can be improved.