Impedance Matching Device for Wireless Power Transmission
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Solution Overview
Problem
Wireless electric power transmission systems based on electromagnetic resonance mode face challenges with impedance mismatch due to variations in coupling state and load values, leading to reflection loss and reduced transmission efficiency, as existing impedance matching circuits are not capable of efficiently and promptly adapting to these changes.
Innovation Solution
An impedance matching device is introduced, featuring an incident-wave/reflective-wave extraction unit, phase determination unit, and variable inductor and capacitor elements in matching circuits, along with a storage unit and control value output unit, which estimates load and coupling coefficients to dynamically adjust matching circuit settings and maintain optimal impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If electromagnetic field resonance coupling mode is used to allow wide gap and robust positional misalignment, then transmission distance and positioning tolerance are improved, but impedance mismatch occurs due to variations in coupling state and load values leading to reflection loss
Solution Approach 1:
The patent applies dynamics by making the impedance matching circuit adjustable and adaptable to changing conditions. The system dynamically adjusts the matching circuit parameters based on detected coupling state and load value variations, transforming a static matching circuit into a dynamic one that can maintain optimal performance across different operating conditions and wide gap distances.
Solution Approach 2:
The patent implements parameter changes by modifying the impedance matching circuit parameters in response to detected variations in coupling state and load values. The system changes electrical parameters (such as capacitance and inductance values) to maintain optimal impedance matching despite changes in transmission distance, coupling state, or load conditions, thereby reducing reflection loss.
2Device complexity
If impedance matching circuit is designed for fixed conditions, then circuit simplicity is maintained, but it cannot adapt to variations in coupling state and load values
Solution Approach 1:
The patent implements feedback by detecting the actual coupling state and load values during operation and using this information to adjust the impedance matching circuit parameters. The system continuously monitors operating conditions and provides feedback to the control mechanism, enabling automatic adaptation to changing conditions while maintaining relatively simple circuit structure.
Solution Approach 2:
The patent applies universality by designing an impedance matching circuit that can handle multiple operating conditions and scenarios. The circuit is made multi-functional through adjustable parameters that allow it to adapt to different coupling states, load values, and transmission distances, replacing the need for multiple fixed matching circuits with a single adaptable solution.
3Reliability
If conventional impedance matching circuits are used, then initial impedance matching can be achieved, but they cannot promptly respond to dynamic changes in coupling state and load
Solution Approach 1:
The patent uses feedback to continuously monitor changes in coupling state and load values and promptly adjust the impedance matching circuit parameters in response. This real-time feedback mechanism enables the system to maintain reliable impedance matching while responding quickly to dynamic changes, overcoming the limitation of conventional fixed matching circuits.
Solution Approach 2:
The patent transforms the static impedance matching circuit into a dynamic one that can respond to changing conditions. By incorporating adjustable parameters and control mechanisms that can modify circuit characteristics in real-time, the system maintains reliable initial matching while gaining the capability to promptly adapt to dynamic changes in coupling state and load.
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 solution effectively maintains high transmission efficiency by continuously matching impedance, reducing reflection loss and ensuring efficient power transfer even with variations in coupling state and load values, thus enhancing the reliability of wireless electric power transmission.
Implementation Method 1
a wireless electric power transmission system transmitting electric power by coupling a power transmission antenna with a power reception antenna through an electromagnetic field
Implementation Method 2
a variable inductor element and a variable capacitor element, the variable inductor element being connected in series between the power transmission circuit and the power transmission antenna
Implementation Method 3
the variable capacitor element being connected in parallel closer to the power transmission antenna than the variable inductor element
Implementation Method 4
a signal reflected from the power transmission antenna
Data Source
AI summary
In an impedance matching device between a power transmission circuit and a power transmission antenna, a storage unit stores tables associated with a load value, each storing control values of a coupling coefficient between the power transmission and reception antennae. A selection unit selects a table corresponding to the load value estimated by the load value estimation unit. An adjustment direction determination unit determines the direction of a position for reading out one of the control values from the selected table. A readout position determination unit determines the position for reading out the control value from the selected table based on the direction and a predetermined step width for shifting the position for reading out the control value. A circuit selection unit electrically connects a matching circuit or the through circuit. A control value output unit outputs the control value at the determined position to the selected circuit.