Resonance Non-Contact Power Shielding for Induced Currents
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Solution Overview
Problem
Resonance-type non-contact power supply systems face inefficiencies and radiated electromagnetic field issues due to large variations in characteristic impedance and induced currents when using coaxial cables, particularly in large-scale systems like electric vehicle charging, leading to significant transmission losses and weight increases when attempting to mitigate these issues with shielding.
Innovation Solution
The implementation of metal shields around primary and secondary resonance coils, electrically connected to coaxial cable outer conductors, to contain electromagnetic fields and improve transmission efficiency without increasing system weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If coaxial cables are used for transmission paths in resonance-type non-contact power supply systems, then transmission efficiency can be maintained, but radiated electromagnetic fields occur due to induced currents in the outer conductor
Solution Approach 1:
A metal shield is introduced as an intermediary component between the resonance coils and the external environment. The shield is electrically connected to the outer conductor of the coaxial cable, serving as a mediator that captures induced currents and redirects them through the designated transmission path, preventing direct radiation while maintaining transmission efficiency
Solution Approach 2:
The invention converts the harmful induced currents in the coaxial cable outer conductor into beneficial directed currents. By connecting the metal shield to the outer conductor, the shield captures the induced currents and channels them through the cable's inner conductor to the load, transforming energy loss into useful power transmission
2Object-generated harmful factors
If shields are used to cover the entire system to prevent induced currents, then radiated electromagnetic fields are reduced, but system weight increases and mounting becomes difficult
Solution Approach 1:
Instead of implementing a complete system-wide shield, the invention segments the shielding function and applies it only to the resonance coil areas where electromagnetic fields are generated. This localized approach reduces the total shield material required, thereby reducing weight while still effectively preventing radiation from the critical sources
Solution Approach 2:
The metal shields are strategically placed only around the primary and secondary resonance coils, which are the specific locations generating electromagnetic radiation. This localized shielding approach provides targeted protection against radiation without the need for comprehensive system-wide shielding, reducing overall weight and simplifying mounting
3Loss of energy
If Litz wires are used to reduce transmission loss, then transmission efficiency improves slightly, but variation of characteristic impedance cannot be reduced
Solution Approach 1:
The metal shield acts as an intermediary that isolates the resonance coils from the coaxial cable's outer conductor. This prevents the cable's characteristic impedance variations from directly affecting the resonance system, while still allowing efficient power transmission through the shield-cable connection
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 significantly reduces radiated electromagnetic fields and enhances transmission efficiency by up to 7% compared to traditional systems, making the technology more suitable for use in mobile applications like electric vehicles.
Implementation Method 1
The resonance system of a high frequency power supply, resonance coils (primary and secondary resonance coils) and a load that transmits electric power non-contactly. Specifically, power-transmission-side (primary side) devices include a high frequency power supply, a primary coil, and a primary resonance coil. Power-receiving-side (secondary device) devices include a secondary resonance coil, a secondary coil and a load.
Implementation Method 2
The resonance system of a high frequency power supply, resonance coils (primary and secondary resonance coils) and a load that transmits electric power non-contactly. The power-transmission-side devices and the power-receiving-side devices in the system have an advantage of being able to supply electric power to a place spaced several meters with a high transmission efficiency (sometimes around 50%) by being magnetically coupled (electromagnetically coupled)) by resonance.
Data Source
AI summary
A resonance-type non-contact power supply system (10) includes a power-transmission-side metal shield (80) to cover an area around a primary coil (30) and a primary resonance coil (35). A coaxial cable outer conductor (64) of a power-transmission-side coaxial cable (60) and the power-transmission-side metal shield (80) are threadedly engaged using a coaxial male connector (66) and a coaxial female connector (86).