Separately Tunable Resonators for Longer-Range Wireless Power
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Solution Overview
Problem
Existing wireless power transfer systems using self-resonating coils face challenges in tuning coils to the RF source frequency and have limited operating range, leading to high operating voltages and inefficiencies due to rapid power decay with distance, which is not suitable for low-voltage electronic devices.
Innovation Solution
The system employs separately tunable transmitter and receiver resonators with variable capacitance to adjust resonant frequencies within 100 kHz to 30 MHz, using air-core coils with a high number of windings and a low number of windings ratio to maintain a low voltage at the input coil, allowing efficient inductive coupling and reducing voltage requirements, along with a full-wave rectifier and DC/DC converter for efficient power conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If high-Q factor resonant systems are used to increase operating range, then power transfer distance is improved, but operating voltage becomes excessively high
Solution Approach 1:
The system divides the voltage management function into two separate resonators: the transmitter resonator generates high voltage for efficient power transfer over distance, while the receiver resonator converts this to low voltage for device compatibility. This segmentation allows each component to optimize for its specific function without compromise
Solution Approach 2:
The receiver resonator acts as an intermediary device that receives high voltage from the transmitter resonator and transforms it into usable low voltage. This intermediate transformation stage resolves the contradiction between needing high voltage for distance and low voltage for device operation
2Loss of energy
If self-resonating coils are used to achieve high-Q factor, then power transfer efficiency is improved, but tuning difficulty increases
Solution Approach 1:
The system replaces fixed self-resonating coils with dynamically tunable resonators that can be independently adjusted. This allows the resonant frequency to be dynamically matched to the RF source frequency and optimized for different operating conditions, maintaining high efficiency while enabling easy tuning
Solution Approach 2:
The invention changes the approach from fixed physical parameters (self-resonating coil geometry) to adjustable electrical parameters (capacitance values). By varying capacitance, the resonant frequency can be precisely tuned without changing the physical coil structure, making the system both efficient and easily adjustable
3Speed
If conventional rectifier circuits are used at high frequencies (5-27 MHz), then power transfer speed is improved, but rectification efficiency decreases due to parasitic resonances
Solution Approach 1:
The system uses feedback control to monitor and adjust the resonant frequency of both transmitter and receiver resonators. This feedback mechanism allows the system to operate at optimal frequencies that maximize power transfer speed while minimizing parasitic resonances and efficiency losses in the rectifier circuit
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 increases the operating range of wireless power transfer, reduces voltage requirements, and improves efficiency by allowing precise tuning and separate tuning of transmitter and receiver resonators, enabling effective power transfer over larger distances and to multiple devices without the need for high-voltage regulators.
Implementation Method 1
a transmitter resonator for wireless transmission of power and a receiver resonator for wireless reception of the power
Implementation Method 2
The second resonator circuit is tuned by the variable capacitance device to a resonant frequency within the range of 100 kHz to 30 MHz
Data Source
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AI summary
A system for wireless energy transfer includes a circuit for wireless transmission of energy, including a first, tunable resonator circuit including a transmitter coil and a variable capacitance device connected in shunt across the transmitter coil. Also disclosed is a circuit for wireless reception of energy including a tunable second resonator circuit including a receiver coil inductively coupled to the transmitter coil and a variable capacitance device connected in shunt across the receiver coil. Also disclosed is an arrangement for wireless energy transmission and reception that foregoes the necessity for separate circuits for DC rectification at the reception end of the arrangement. Also disclosed a system for wireless energy transfer where the system includes a tunable resonator circuit embedded in a surface such as piece of furniture, counter, etc., e.g., a table.