Wireless Power Resonator Impedance Switching for Coil Variation

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Solution Overview

Problem

Variations in the size, shape, or relative position of the power receiving coil can reduce magnetic-flux changes, causing the power transmission coil to fail to resonate with the power receiving coil, resulting in incomplete or failed power transfer in wireless power transfer systems.

Innovation Solution

A power transmission apparatus with a power transmission resonator that includes a power transmission coil and a resonance capacitor unit, along with a switching unit to control the input impedance of the resonator, allowing for controlled current flow and reliable power transfer by receiving a power-transfer request signal from the power receiving apparatus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the power transmission system relies on magnetic-flux change to detect power receiving coil position and initiate power transfer, then the system can automatically start power transfer when coils are properly aligned, but variations in coil size, shape, or position reduce magnetic-flux change and cause power transfer to fail to start

Engineering Contradiction:

Improvepower transfer initiation reliabilityVSAvoidcoil position and size variation tolerance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system continuously monitors the magnetic flux induced in the power transmission coil and uses this feedback to detect the presence and position of the power receiving coil. When the monitored magnetic flux indicates proper alignment, the system automatically initiates power transfer by adjusting the input impedance of the resonator.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical alignment detection methods with electromagnetic field-based detection. Instead of using mechanical switches or physical contact to detect coil alignment, the system uses changes in magnetic flux and electromagnetic coupling to automatically detect when the power receiving coil is properly positioned relative to the power transmission coil.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the system uses variable capacitor to change input impedance for resonance control, then the system can switch between power transfer and standby states, but the impedance control may not be sufficient when magnetic-flux change is reduced due to coil variations

Engineering Contradiction:

Improveautomatic power transfer controlVSAvoidpower transfer initiation reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system dynamically adjusts the input impedance of the power transmission resonator based on real-time detection of magnetic flux changes. The variable capacitor is controlled to change capacitance values dynamically, allowing the system to adapt the resonance conditions and maintain reliable power transfer initiation despite variations in coil position or configuration.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the capacitance parameter of the variable capacitor to control the input impedance of the resonator. By adjusting the capacitance value, the system modifies the resonant frequency and impedance characteristics of the power transmission coil, enabling reliable detection and initiation of power transfer under varying operational conditions.

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

This configuration ensures reliable power transfer initiation and prevents glitches by adjusting the resonator's impedance in response to the power receiving coil's position, ensuring efficient energy transfer even with variations in coil size or position.

Implementation Method 1

magnetic flux induced in a power transmission coil of the power transmission device changes depending on whether a power receiving coil of the power receiving device is in a facing state

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

This causes the power transmission coil and power receiving coil to resonate with each other, and therefore the input impedance of the power-transmitting resonator is changed

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS20240424922A1Power transmission apparatus, wireless power transfer system, and power transmission method and program

Publication Date: 2024.12.26 DENSO CORP

AI summary

A power transmission apparatus for wireless power transfer to a movable power receiving apparatus includes a power transmission resonator that includes a power transmission coil and a transmission resonance capacitor unit, and a power transmission circuit for supply of alternating-current power to the power transmission resonator. The power transmission apparatus includes a power-transfer request signal receiver configured to receive a power-transfer request signal transmitted from the power receiving apparatus, and a switching unit. The switching unit is configured to, when the power-transfer request signal receiver receives the power-transfer request signal, change an input impedance of the power transmission resonator to change a value of current flowing through the power transmission coil of the power transmission resonator to a controlled value enabled to transfer power from the power transmission coil to the power receiving apparatus.