Variable Reactance Resonant Network for Wireless Power Stability
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Solution Overview
Problem
Wireless power transfer systems face instability and potential damage to amplifier circuits due to sudden changes in the number of devices being charged, leading to fluctuations in reflected reactance, which can exceed the operational range of the amplifier.
Innovation Solution
A resonant network with a variable reactance element, controlled by a circuit that adjusts its reactance based on an indication of the source reactance, allowing the system to operate either below or above resonance to maintain a desired output and reduce reflected reactance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless power transfer systems charge multiple electronic devices simultaneously, then the charging capacity and productivity are improved, but the reflected reactance fluctuates and may exceed amplifier operational range, causing instability and potential damage
Solution Approach 1:
The patent implements dynamic adjustment of the resonant network's reactance through variable capacitive elements that can be tuned in real-time. The system continuously monitors the reflected reactance and adjusts the resonant frequency to maintain optimal operation when the number of charged devices changes, preventing reflected reactance from exceeding amplifier operational range while maintaining multi-device charging capability
Solution Approach 2:
The system employs feedback control by monitoring the reflected reactance from the wireless power transfer system and using this information to adjust the resonant network's reactance. The controller receives feedback about the current charging state and modifies the capacitive elements accordingly to maintain system stability and prevent amplifier damage when device count varies
2Use of energy by moving object
If the resonant network operates at resonant reactance value, then the power transfer efficiency is maximized, but the reflected reactance becomes highly sensitive to device number changes, causing instability
Solution Approach 1:
The patent changes the operating parameter of the resonant network from fixed resonant reactance to variable reactance that can operate at or near resonance dynamically. By adjusting the capacitive elements in the resonant network, the system can maintain high power transfer efficiency while adapting the reactance to compensate for device number changes, preventing reflected reactance instability
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 approach stabilizes the output power transfer, prevents amplifier damage, and ensures efficient energy delivery by dynamically adjusting the resonant network's reactance in response to changes in the number of devices being charged.
Implementation Method 1
a resonant network including a variable reactance element, such that the resonant network is configured to resonant when the variable reactance element is at a resonant reactance value
Implementation Method 2
The variable reactance element may include at least one variable capacitor
Implementation Method 3
The power receiving unit may include at least one coil configured to inductively couple power via a magnetic field
Data Source
AI summary
Techniques for reducing reflected reactance in a wireless power transfer system are provided. An example apparatus includes a resonant network including a variable reactance element, such that the resonant network is configured to resonant when the variable reactance element is at a resonant reactance value, a control circuit operably coupled to the variable reactance element and configured to determine a first reactance value and a second reactance value, such that an output of the PRU is the desired output when the variable reactance element is either the first reactance value or the second reactance value, and the first reactance value is below the resonant reactance value and the second reactance value is above the resonant reactance value, determine an indication of a source reactance associated with a wireless power source, and adjust the variable reactance element to either the first reactance value or the second reactance value based on the indication of the source reactance.