Wireless Power Coil Impedance Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless power-supplying systems, positional misalignment between power-transmitting and power-receiving coils leads to changes in the coupling coefficient, causing variations in impedance, which can decrease charging efficiency due to increased Joule heat loss and the need for high-voltage circuit elements or increased output current.
Innovation Solution
A wireless power-supplying system that includes a power-transmitting device with a controller that adjusts the frequency based on the coupling coefficient changes, ensuring the impedance remains constant by maintaining a predetermined relationship between the power-transmitting and power-receiving coils, using series elements with imaginary impedance to stabilize the impedance seen from the power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency is changed to compensate for coupling coefficient changes, then the power transmission efficiency is improved, but the impedance varies causing output voltage or current changes
Solution Approach 1:
The patent applies parameter changes by introducing imaginary impedance parameters (jZS1i and jZS2i) that are specifically designed to counteract the real impedance changes caused by coupling coefficient variations. By adjusting these imaginary impedance parameters in coordination with frequency changes, the system maintains constant total impedance while improving power transmission efficiency.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the coupling coefficient and using this information to adjust both the frequency and imaginary impedance parameters. The controller receives feedback about the actual coupling condition and dynamically adjusts the system parameters to maintain optimal performance and constant impedance.
2Power
If the output voltage of the inverter circuit is increased to maintain power transmission, then high-voltage circuit elements are required increasing device size, but if the output voltage is decreased then output current must increase causing increased Joule heat loss
Solution Approach 1:
The patent changes the impedance parameters by introducing imaginary impedance components that allow the system to maintain constant total impedance. This enables the use of lower voltage and current levels while maintaining the same power transmission capability, thereby reducing Joule heat loss without requiring high-voltage circuit elements.
3Productivity
If the coupling coefficient changes due to positional misalignment, then power transmission efficiency decreases, but changing frequency to compensate causes impedance variation
Solution Approach 1:
The patent simultaneously changes two parameters: the frequency and the imaginary impedance. By coordinating these changes, the system compensates for coupling coefficient variations caused by positional misalignment while maintaining constant total impedance. The imaginary impedance parameter is specifically adjusted to counteract the impedance changes that would otherwise occur with frequency adjustment alone.
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 solution effectively suppresses impedance variations when the coupling coefficient changes, maintaining efficient power transmission and reducing heat loss and the need for high-voltage components by ensuring the impedance remains constant, thus enhancing charging efficiency.
Implementation Method 1
Wireless power-supplying systems which supply power using electromagnetic induction, magnetic field resonance
Implementation Method 2
magnetic flux generated by the power-transmitting coil is interlinked with the power-receiving coil, and thereby power is transmitted between the coils
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A wireless power-supplying system (100) according to the present disclosure includes a power-transmitting device (101) and a power-receiving device (103), in which the power-transmitting device includes a power-transmitting coil (113) to which AC power of a certain frequency is input from a power supply (111) and a controller which controls a frequency, the power-receiving device includes a power-receiving coil (121) magnetically coupled with the power-transmitting coil with a certain coupling coefficient and a power-receiving side series element (123) connected to the power-receiving coil in series and having imaginary impedance jZS2i, the imaginary impedance is defined so that impedance when a power-receiving side is seen from the power supply is independent of the coupling coefficient when the frequency and the coupling coefficient are predetermined values, and the controller changes the frequency according to at least one of power-transmitting status information of the power-transmitting device and power-receiving status information of the power-receiving device when the coupling coefficient changes.