Wireless Power Feeding Equipment Reflected Power Protection
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Solution Overview
Problem
When resonance is used to transfer electric power to electric vehicles or similar mobile objects, variations in distance between resonant coils lead to impedance mismatches between the resonance system and the electric power supply device, resulting in reduced efficiency and potentially damaging reflected power.
Innovation Solution
The implementation of wireless electric power feeding equipment that includes an electric power supply device, a detection device to monitor reflected power, a discharging coil for external discharge, and a connection device to electrically connect the discharging coil when reflected power exceeds a predetermined value, along with an electromagnetic shielding material and a variable impedance device to adjust impedance and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonance is used to transfer electric power wirelessly to mobile objects, then power transfer efficiency and transfer distance are improved, but impedance mismatch occurs when distance varies causing reflected power to increase
Solution Approach 1:
A discharging coil is introduced as an intermediary component between the power supply device and the resonance system. This discharging coil acts as a mediator to handle reflected power, allowing it to be discharged safely to ground rather than returning to damage the power supply device. The connection device controls when to connect this intermediary path based on detected reflected power levels.
Solution Approach 2:
The system employs a feedback mechanism where the detection device continuously monitors reflected power levels and provides this information to the connection device. When reflected power exceeds a predetermined threshold, the connection device activates to connect the discharging coil, creating a closed-loop control system that dynamically responds to impedance mismatch conditions and protects the power supply device.
2Reliability
If a discharging coil is connected to externally discharge reflected power, then equipment safety is improved, but device complexity increases
Solution Approach 1:
The discharging coil serves multiple functions: it acts as a normal coil during standard power transfer operations and simultaneously serves as a protective discharge path when reflected power occurs. The connection device and detection device work together to enable this multi-functionality, allowing the same hardware component to perform both routine and protective roles without requiring entirely separate systems.
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
Prevents rapidly increased reflected power from damaging the electric power supply device by externally discharging excess power, thereby maintaining efficient power transfer and protecting the equipment.
Implementation Method 1
power transfer through resonance causes a pair of resonators (e.g., a pair of coils) to resonate in an electromagnetic field (a near field) to transfer electric power through the electromagnetic field in a contactless manner
Implementation Method 2
The electric power transfer unit receives electric power from the electric power supply device and transfers the electric power to the electric power receiving unit in a contactless manner by resonating with the electric power receiving unit via an electromagnetic field
Implementation Method 3
The discharging coil externally discharges electric power output from the electric power supply device
Data Source
AI summary
An electric power supply device generates electric power having a prescribed frequency. An electric power transfer unit receives electric power from the electric power supply device, and transfers electric power to an electric power receiving unit in a contactless manner by resonating with the electric power receiving unit via an electromagnetic field. An electric power sensor senses power reflected to the electric power supply device. A discharging coil unit externally discharges electric power output from the electric power supply device. A relay electrically connects the discharging coil unit between the electric power supply device and the electric power transfer unit when the reflected power detected has a value exceeding a predetermined value.