Detection apparatus, electric power receiving apparatus, electric power transmission apparatus, wireless electric power transmission system, and detection method
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Solution Overview
Problem
Existing non-contact wireless electric power transmission systems face challenges in accurately detecting metal foreign matter between the transmission and receiving sides, particularly due to the influence of metal housing, which complicates differentiation from actual foreign matter, leading to reduced detection accuracy.
Innovation Solution
The system switches the circuit configuration of the resonance circuit between power supply and metal foreign matter detection phases, increasing the electrostatic capacitance value to enhance the signal-to-noise ratio and improve detection accuracy without compromising power supply efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electrostatic capacitance value is increased to improve detection accuracy, then the signal-to-noise ratio improves, but the power supply efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the circuit configuration adjustable between two states: a first configuration optimized for power supply efficiency and a second configuration optimized for detection accuracy. The system dynamically switches between these configurations based on operational requirements, allowing the electrostatic capacitance value to be changed without permanent compromise to either function.
Solution Approach 2:
The patent implements periodic action by alternating between power supply phases and detection phases. During detection phases, the system switches to the second circuit configuration with increased electrostatic capacitance to improve signal-to-noise ratio, then returns to the first configuration for efficient power supply. This periodic switching allows both functions to operate at their respective optima at different times.
2Reliability
If a temperature sensor is used to detect metal foreign matter, then detection capability is achieved, but design restrictions are imposed on transmission and reception devices
Solution Approach 1:
The patent replaces the mechanical/thermal sensing approach (temperature sensors requiring thermal contact and specific thermal conductivity) with an electromagnetic sensing approach. By detecting changes in the resonance circuit's characteristics (such as Q-value or resonant frequency) caused by eddy currents in metal foreign matter, the system achieves detection without physical contact or thermal coupling requirements.
Solution Approach 2:
The patent introduces an intermediary detection method using the resonance circuit itself as the sensing element. Instead of using separate temperature sensors that require thermal coupling, the system uses the existing electromagnetic field and resonance circuit to indirectly detect metal foreign matter through changes in circuit parameters, thereby eliminating direct thermal contact requirements.
3Measurement precision
If the circuit configuration is switched to increase electrostatic capacitance, then the amplitude of voltage measurements increases, but the system complexity increases
Solution Approach 1:
The patent applies universality by designing the resonance circuit to serve multiple functions: it acts as both the power transmission resonance circuit and the detection resonance circuit. The same circuit components (inductor and capacitor) are used for both power supply and foreign matter detection, eliminating the need for separate dedicated detection circuits and reducing overall system complexity despite the switching requirement.
Solution Approach 2:
The patent merges the power supply function and detection function into a single integrated resonance circuit system. By combining these functions, the patent avoids the complexity of maintaining separate independent circuits, and the switching between configurations becomes a matter of reconfiguring existing components rather than coordinating multiple 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
This approach allows for more accurate detection of metal foreign matter by increasing the amplitude of voltage measurements and improving the signal-to-noise ratio, thereby enhancing the overall detection precision without affecting electric power supply performance.
Implementation Method 1
a technique called a magnetic-field resonance method in which a resonance phenomenon is actively used
Implementation Method 2
One of the techniques is an already widely used electromagnetic induction method
Implementation Method 3
when electric power supply is to be performed in a non-contact manner, in the case where a metal is present between the electric power transmission side and the electric power receiving side, an eddy current is generated, and there is a risk that the metal will generate heat
Data Source
AI summary
A method for wireless power transmission includes obtaining, via a Q-value circuit, first and second voltages at respective first and second nodes of a resonance circuit. The first and second voltages are effective to determine if foreign matter is present in a space affecting wireless power transmission. The method includes controlling a switching section between the Q-value circuit and the resonance circuit such that at least a part of the electric power transmission process occurs at a different time than when the first and second voltages are obtained.