Wireless Power Receiver Impedance Stabilization
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Solution Overview
Problem
Wireless power supply systems face efficiency issues due to positional misalignment between power-transmitting and power-receiving coils, leading to fluctuations in impedance and reduced charging efficiency, as the coupling coefficient changes, requiring a solution to stabilize impedance seen from the power source.
Innovation Solution
A wireless power supply system is designed with a power transmitter and receiver, where the power transmitter includes a power-transmitting coil and a series element with imaginary impedance, and the power receiver includes a power-receiving coil magnetically coupled with a series element, determining frequency, coupling coefficient, and imaginary impedance to maintain constant impedance independent of the coupling coefficient, using specific formulas to optimize coil interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency is changed to compensate for coupling coefficient changes, then charging efficiency is improved, but impedance fluctuation occurs and requires higher output voltage
Solution Approach 1:
The patent changes the frequency parameter of the AC power supplied to the power-transmitting coil in response to coupling coefficient changes. By adjusting the frequency, the system compensates for variations in magnetic coupling, thereby maintaining charging efficiency while managing impedance fluctuations through dynamic parameter adaptation.
Solution Approach 2:
The system dynamically adjusts the operating frequency based on real-time coupling conditions. This dynamic adaptation allows the power transmission system to respond to changing positional relationships between coils, optimizing efficiency while the inverter circuit manages voltage output to address impedance variations.
2Loss of energy
If the coupling coefficient changes due to positional misalignment, then transmission efficiency decreases, but changing frequency causes impedance change
Solution Approach 1:
The patent employs frequency as a controllable parameter to counteract the effects of coupling coefficient variations. When positional misalignment causes coupling changes, the system adjusts the frequency of the supplied AC power to optimize magnetic flux interlinking, thereby recovering transmission efficiency while the inverter dynamically manages the resulting impedance changes through voltage adjustment.
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 configuration effectively suppresses impedance fluctuations at the power-receiving side, ensuring stable power transmission and reduced Joule heat loss, even with changes in the coupling coefficient, thereby enhancing charging efficiency and system reliability.
Implementation Method 1
magnetic flux generated by the power-transmitting coil is interlinked with the power-receiving coil, whereby electric power is transmitted between the coils
Implementation Method 2
changes in a coupling coefficient and an imaginary impedance of a series element compensate each other, so that a total impedance is independent of a coupling coefficient
Data Source
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AI summary
A wireless power supply system of the present disclosure includes: a power transmitter having a power-transmitting coil to which AC power of a frequency is input from a power source; and a power receiver having a power-receiving coil magnetically coupled to the power-transmitting coil at a coupling coefficient, and a first power-receiving-side series element coupled in series to the power-receiving coil and having imaginary impedance jZS2i, in which the frequency, the coupling coefficient and the imaginary impedance are determined on the basis of satisfying the following formula. |I2I1|=KIL1L2