Switched Capacitor Tuning for Wireless Power Transfer
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Solution Overview
Problem
Conventional wireless power transfer systems for implantable medical devices are inefficient due to sensitivity to coil alignment and position variations, requiring precise capacitor values that are difficult to achieve with existing components, leading to a tedious and costly manufacturing process.
Innovation Solution
A wireless power transfer system with switched capacitor circuits and a controller that adjusts the effective capacitance by switching MOSFETs to optimize power transfer efficiency and coupling coefficient, allowing for precise tuning of resonant frequencies and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fixed-value capacitors are used in wireless power transfer systems, then the system structure is simple, but the power transfer efficiency is low due to sensitivity to coil alignment and position variations
Solution Approach 1:
The patent applies dynamics by transitioning from fixed-value capacitors to dynamically adjustable switched capacitor circuits. The capacitor value can be changed in real-time based on coil alignment and position variations, allowing the system to adapt to changing conditions and maintain optimal power transfer efficiency. The switched capacitor circuit enables continuous adjustment of capacitance values to compensate for misalignment between transmit and receive coils.
Solution Approach 2:
The patent implements parameter changes by varying the capacitance value through switched capacitor configurations. By changing the effective capacitance parameter in response to alignment variations, the resonant frequency can be adjusted to maintain optimal power transfer. This allows the system to compensate for positional changes by modifying the electrical parameter (capacitance) rather than requiring precise mechanical alignment.
2Reliability
If precise capacitor values are used to achieve low resistance and large quality factor, then the power transfer efficiency is improved, but the manufacturing process becomes tedious and expensive
Solution Approach 1:
Instead of manufacturing capacitors with precise fixed values, the patent uses dynamic adjustment through switched capacitor circuits. Standard-value capacitors can be used in manufacturing, and the precise effective capacitance is achieved through electronic switching and control algorithms. This eliminates the need for tedious capacitor selection and trimming during manufacturing while maintaining high power transfer efficiency.
Solution Approach 2:
The system performs self-tuning through the switched capacitor circuit and controller, automatically adjusting the effective capacitance to achieve optimal resonant frequency and power transfer efficiency. This self-adjusting capability eliminates the need for manual capacitor selection and trimming processes, significantly simplifying manufacturing while maintaining precise capacitance control.
3Reliability
If resonators with large quality factor are used, then the power transfer efficiency is improved, but the frequency band becomes very narrow requiring precise frequency matching
Solution Approach 1:
The patent applies dynamics by making the capacitance adjustable through switched capacitor circuits, which enables the resonant frequency to be dynamically tuned. This allows the system to maintain a large quality factor for efficient power transfer while compensating for frequency drift and variations in coil positioning through real-time frequency adjustment, effectively widening the operational frequency band.
Solution Approach 2:
By changing the capacitance parameter through switched capacitor configurations, the system can adjust the resonant frequency to match varying operating conditions. This parameter adjustment capability allows the system to maintain optimal frequency matching despite variations in coil alignment, distance, or environmental factors, effectively increasing frequency tolerance while preserving high power transfer efficiency.
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 system enhances power transfer efficiency and coupling coefficient by dynamically adjusting capacitance, reducing the need for precise capacitor matching and improving system performance across varying environmental conditions.
Implementation Method 1
an inductor adapted to receive or transmit wireless power
Implementation Method 2
first and second switched capacitor circuits electrically connected to opposite poles of the inductor, each of the first and second switched capacitor circuits comprising a first capacitor in series with a MOSFET and a second capacitor in parallel with the first capacitor
Implementation Method 3
resonant power transfer systems
Data Source
AI summary
Systems and designs for tuning a wireless power transfer system are provided, which may include any number of features. In one embodiment, a wireless power transfer system can include first and second switched capacitor circuits electrically connected to opposite poles of the inductor of a resonator in the wireless power system. The first and second switched capacitor circuits can be switched on and off with MOSFETS to change a capacitance of the circuits, and thus an effective capacitance of the resonator. Methods of use are also provided.