Microwave Wireless Power Transfer Using Frequency Switching
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Solution Overview
Problem
Current wireless charging methods are limited to short distances, making it difficult to charge batteries or power equipment located far from a mains power source.
Innovation Solution
A system using a microwave receiver, matching network, and transducer to convert a focused microwave beam into a direct current (DC) voltage, enabling wireless power transfer over long distances by generating a microwave signal, switching it to a different frequency, and using a transducer to produce a DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If magnetic resonance wireless charging is used, then power can be transferred wirelessly, but the transfer distance is limited to relatively short distances (e.g., an inch)
Solution Approach 1:
The patent changes the frequency parameter of the electromagnetic signal from low-frequency magnetic resonance (e.g., 6.78 MHz) to high-frequency microwave (e.g., 2.45 GHz or 5.8 GHz). This parameter change enables the system to overcome the short distance limitation of magnetic resonance charging while maintaining efficient power transfer over distances greater than 10 feet through the use of directional microwave antennas and focused beam transmission.
2Length of stationary object
If microwave signals are used for wireless power transfer, then power can be transferred over long distances, but the system complexity increases
Solution Approach 1:
The patent introduces a microwave receiver as an intermediary device that captures the transmitted microwave signals and converts them to lower frequency signals suitable for rectification. This intermediary component simplifies the overall system by separating the long-distance transmission function (microwave transmitter) from the power conversion function (receiver and rectifier), allowing each component to be optimized independently.
Solution Approach 2:
The patent replaces complex electromagnetic coupling mechanisms with a simpler microwave transmission approach using directional antennas. Instead of relying on complex magnetic resonance coupling between coils, the system uses focused microwave beams that can be precisely directed to the receiver, reducing the complexity of the coupling mechanism while extending the transfer distance.
3Length of stationary object
If microwave energy is converted to DC voltage, then remote power supply is enabled, but energy loss occurs during frequency conversion
Solution Approach 1:
The patent performs frequency switching before rectification, converting the microwave carrier frequency to a lower intermediate frequency while the signal is still in the electromagnetic domain. This preliminary frequency conversion reduces the energy loss that would occur during direct rectification of high-frequency microwaves, as the lower frequency signal is more efficiently processed by the rectifier circuit.
Solution Approach 2:
The patent optimizes the frequency conversion process by selecting specific microwave frequencies (2.45 GHz or 5.8 GHz) that align with standard rectifier operating ranges. By changing the frequency parameter to values that are more efficiently handled by available rectification technology, the system minimizes energy loss during the conversion from microwave to DC voltage.
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
Enables efficient wireless power transfer over distances greater than 10 feet, effectively utilizing microwave energy to generate DC voltage for remote power supply.
Implementation Method 1
A microwave receiver receives a microwave signal having a carrier frequency. The matching network receives a signal having the carrier frequency and a switched frequency and removes the carrier frequency such that the matching network outputs a switched signal at the switched frequency.
Implementation Method 2
The transducer receives the switched signal and outputs a DC voltage.
Data Source
AI summary
A wireless power source including a microwave receiver, a matching network, and a transducer. The microwave receiver receives a microwave signal having a carrier frequency. The matching network receives a signal having the carrier frequency and a switched frequency and removes the carrier frequency such that the matching network outputs a switched signal at the switched frequency. The transducer is configured to receive the switched signal and output a DC voltage.