Contactless Power Receiving Device Abnormality Protection

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Solution Overview

Problem

In contactless power supply systems using electromagnetic resonance, there is a risk of device degradation or breakage due to residual energy transmission when a power receiving device experiences an abnormality, leading to unintended power supply to faulty devices or environmental influence.

Innovation Solution

A power receiving device equipped with a discharging unit, including a resistor and switching units, that discharges received electric power when an abnormality is detected, preventing further supply to the electrical storage device and ensuring safe energy dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If power transmission continues using resonance method when abnormality is detected, then power transmission efficiency is maintained, but device degradation or breakage occurs due to residual energy transmission

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoiddevice safety
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control unit detects abnormalities in the power receiving device during normal operation and proactively stops power transmission before residual energy can cause damage. This preliminary action prevents device degradation while maintaining safety, resolving the contradiction between transmission efficiency and device reliability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system converts the potentially harmful residual energy from resonance into a controlled discharge process. By detecting abnormalities and stopping transmission, the residual energy is naturally dissipated without causing damage, transforming a harmful effect into a safe operational characteristic

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If power transmission is quickly stopped when abnormality is detected, then device protection is achieved, but residual energy remains in resonance coils causing continued transmission

Engineering Contradiction:
Improvedevice protectionVSAvoidresidual energy dissipation
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The resonance coils naturally dissipate residual energy through their own physical characteristics after power transmission is stopped. The system leverages the inherent energy decay properties of the resonance coils rather than requiring active discharge mechanisms, achieving both protection and energy dissipation

Inventive Principle:
Principle #25Self-service

3Reliability

If discharging unit is added to power receiving device, then abnormality protection is improved, but device complexity increases

Engineering Contradiction:
Improveabnormality protectionVSAvoiddevice structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The discharging unit is integrated into the existing power receiving device structure, combining the discharge function with the power reception components. This merging approach provides abnormality protection while minimizing the increase in device complexity by sharing structural elements and control logic

Inventive Principle:
Principle #5Merging (Combining)

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 protects the power receiving device by stopping power transmission and safely dissipating residual energy, preventing damage and environmental impact during abnormal conditions.

Implementation Method 1

a power receiving unit that carries out electromagnetic resonance with a power transmitting unit included in the power transmitting device to thereby receive electric power from the power transmitting device

Methodology Applied
Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 2

a discharging unit that, when there is an abnormality in the power receiving device, discharges received electric power received by the power receiving unit

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2721718B1Power receiving device, power transmitting device, vehicle, and contactless power supply system
Publication Date: 2018.07.18 TOYOTA JIDOSHA KK
  • EP2721718B1 patent drawingFigure 1
  • EP2721718B1 patent drawingFigure 2
  • EP2721718B1 patent drawingFigure 3~4

AI summary

A power supply system (10) includes: a power transmitting device (200) that includes a power transmitting unit (220); and a vehicle (100) that includes a power receiving unit (110), and contactlessly transfers electric power between the power transmitting device (200) and the vehicle (100) through electromagnetic resonance. When there is an abnormality that a power receiving mechanism of the vehicle (100) cannot receive electric power, a vehicle ECU (300) causes the power transmitting device (200) to stop power transmission, opens a relay (RY20) and further discharges remaining electric power by the discharging unit (186).