Ferrite Antenna Coil Positioning for Wireless Power Q Stability
Solution Overview
Problem
Ferrite rod antennas face challenges with Q degradation at higher magnetic field strengths and resonance frequency shifts due to hysteresis losses and nonlinearity, limiting their effectiveness in wireless power transfer, especially at higher power levels.
Innovation Solution
The use of specially designed ferrite antennas with adjustable coil positions and tuning mechanisms to maintain high Q factors and optimal resonance frequencies, even at increased power levels, by mechanically or electronically adjusting the coil position to compensate for nonlinear effects and hysteresis losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ferrite rod antennas are used for wireless power transfer, then power transfer capability is improved, but Q degradation occurs at higher magnetic field strengths due to hysteresis losses
Solution Approach 1:
The patent implements a movable coil assembly that can be adjusted along the ferrite rod to dynamically optimize the antenna's resonant frequency and Q factor. This dynamic adjustment capability allows the system to compensate for Q degradation at higher power levels by repositioning the coil to maintain optimal coupling with the ferrite rod, thereby resolving the contradiction between power transfer capability and energy loss.
Solution Approach 2:
The system changes the physical parameter of coil position along the ferrite rod to optimize performance. By adjusting the coil's position, the effective inductance and coupling coefficient change, allowing the antenna to maintain high Q values even at higher magnetic field strengths where hysteresis losses would normally degrade performance.
2Power
If ferrite rod antennas operate at higher power levels, then wireless power transfer efficiency is improved, but resonance frequency shifts occur due to nonlinearity
Solution Approach 1:
The movable coil assembly enables dynamic tuning of the resonant frequency by adjusting the coil's position along the ferrite rod. As power levels increase and nonlinearity causes frequency shifts, the system can reposition the coil to restore the resonant frequency to its optimal value, maintaining reliable operation at higher power levels.
Solution Approach 2:
The system incorporates feedback mechanisms to detect resonance frequency shifts and automatically adjust the coil position to compensate for nonlinear effects at higher power levels, thereby maintaining frequency stability and reliable power transfer.
3Device complexity
If coil position is fixed on ferrite rod, then device complexity is reduced, but tuning capability to compensate for nonlinear effects is lost
Solution Approach 1:
The patent implements a simple yet effective movable coil assembly that can be adjusted along the ferrite rod. This dynamic structure provides tuning capability to compensate for nonlinear effects and hysteresis losses without significantly increasing device complexity, as the movement mechanism is straightforward and integrates well with the ferrite rod antenna structure.
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 ensures that the ferrite antennas maintain high Q values and proper resonance frequencies, enabling efficient wireless power transfer up to higher power levels without significant detuning, as demonstrated by measurements showing Q values above 100 up to 100 mW and effective power transfer characteristics.
Implementation Method 1
Ferrite structures concentrate magnetic flux lines into the structure, thereby creating a magnetic path/field with less interference and eddy current losses in device electronics.
Implementation Method 2
two high-Q antennas are placed such that they react similarly to a loosely coupled transformer, with one antenna inducing power into the other
Implementation Method 3
Ferrite rod antennas face challenges with Q degradation at higher magnetic field strengths and resonance frequency shifts due to hysteresis losses and nonlinearity
Data Source
AI summary
This disclosure provides systems, methods and apparatus for wireless power transfer using resonant ferrite antennas to transmit and receive power. Ferrite structures concentrate magnetic flux lines into the structure, thereby creating a magnetic path and field with less interference and eddy current losses than in device electronics, thereby improving the efficiency of magnetic power distribution. The disclosure describes tuning the resonance frequency by mechanically adjusting the position of the coil on the rod. The ferrite rod antennas described herein may be used to transfer power to handheld communication devices.