Wireless Power Coil Switching for Adjacent Coupling Control
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Solution Overview
Problem
Existing wireless power supply systems for mobile bodies fail to consider coupling between multiple power transmission coils, leading to difficulties in setting a threshold for impedance adjustment when coils are in close proximity, which affects current flow and resonance states.
Innovation Solution
A wireless power supply system with a switching control unit that adjusts the resonance state of power transmission units based on the magnitude of magnetic flux, using a threshold value that accounts for coupling between adjacent coils to ensure efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple power transmission coils are placed in close proximity to each other to cover the moving range, then the power supply coverage is improved, but coupling occurs between adjacent coils which changes the current flow and makes it difficult to set a threshold for impedance adjustment
Solution Approach 1:
The patent applies dynamics by making the impedance of power transmission coils adjustable rather than fixed. The switching control unit dynamically changes the impedance state of each coil based on real-time detection of magnetic flux magnitude, allowing the system to adapt to varying coupling conditions as the mobile body moves through different positions, thus resolving the contradiction between maintaining coverage and avoiding coupling interference.
Solution Approach 2:
The patent changes the impedance parameter of the power transmission coils based on detected magnetic flux levels. When coupling is detected (magnetic flux exceeds threshold), the impedance is switched to a high state to suppress current flow in that coil, preventing harmful interference. This parameter change allows the system to maintain both wide coverage and clean power transmission by selectively adjusting coil characteristics.
2Object-affected harmful factors
If impedance is increased to suppress current flow when coupling occurs, then harmful current flow is reduced, but power transmission efficiency decreases when the coil should be active
Solution Approach 1:
The patent implements feedback control by continuously detecting the magnetic flux magnitude around each power transmission coil and using this information to control the switching of impedance states. The switching control unit receives feedback about the electromagnetic environment and adjusts the coil impedance accordingly, ensuring that high impedance is only applied when actually needed to suppress harmful currents, thereby maintaining high power transmission efficiency when coils are properly isolated.
Solution Approach 2:
The system dynamically adjusts the impedance state of each coil based on real-time conditions rather than maintaining a static high or low state. This allows the system to minimize energy loss by keeping coils in low-impedance (efficient transmission) state when no coupling is present, and only switching to high-impedance (suppression) state when coupling is detected, thus resolving the contradiction between suppressing harmful currents and maintaining transmission efficiency.
3Extent of automation
If a threshold value is set for impedance switching, then automatic control of power transmission is achieved, but it becomes difficult to determine an appropriate threshold when coupling between coils changes the current characteristics
Solution Approach 1:
The patent uses feedback from magnetic flux detection to automatically determine when impedance switching is needed. The switching control unit monitors the magnetic flux magnitude and compares it against a predetermined threshold, automatically adjusting the coil impedance state without manual intervention. This feedback mechanism resolves the threshold setting problem by using real-time electromagnetic field measurements to trigger switching decisions.
Solution Approach 2:
The system performs self-diagnosis and self-adjustment by automatically detecting coupling conditions through magnetic flux measurement and autonomously switching impedance states without external control. Each power transmission unit essentially monitors its own environment and adjusts its own impedance, making the threshold detection and application fully automatic and eliminating the need for manual calibration despite varying coupling conditions.
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
The system effectively manages resonance and non-resonance states of multiple power transmission units, ensuring stable and efficient power delivery to a power receiving unit by appropriately switching between states based on magnetic flux thresholds.
Implementation Method 1
supply power to a power receiving unit via the power transmission coil in a resonance state
Implementation Method 2
supply power to a power receiving unit via the power transmission coil in a resonance state
Implementation Method 3
adjacent power transmission coils are coupled to each other. When coupling occurs between the power transmission coils, the coupling changes the current flowing from the high-frequency power source to the power transmission coils
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A wireless power supply system (100) that wirelessly supplies power to a mobile body (200) including a power receiving unit (280) includes an AC power supply unit (20) and a plurality of power transmission units (80), the plurality of power transmission units are disposed in at least a part of a moving range of the moving body and include a power transmission coil (81). The wireless power supply system includes a plurality of power transmission units that receive a supply of power from the AC power supply unit and supply power to a power receiving unit via the power transmission coil in a resonance state, and a switching control unit that switches a state of a first power transmission unit (80a) to a resonance state when the magnitude of the magnetic flux generated in a first power transmission coil (81a) of the first power transmission unit, which is one of the plurality of power transmission units, is greater than a predetermined threshold value, and switches to a non-resonance state when the magnitude is less than the threshold value. The threshold is set as a magnitude that exceeds the magnetic flux generated in the first power transmission coil due to a coupling between the first power transmission coil and a second power transmission coil (81b) of a second power transmission unit (80b), which is adjacent to the first power transmission coil.