Wireless Power Receiver With PWM Impedance Control
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Solution Overview
Problem
Current wireless power transfer technologies face inefficiencies and practical limitations, such as rapid power coupling decline with distance in far-field methods and the need for precise antenna alignment in near-field approaches, making them unsuitable for widespread and flexible use in telemetry systems and monitoring devices.
Innovation Solution
A wireless power receiver system with a rectifier and a pulse-width modulation (PWM) controller that adjusts the alternating current impedance based on the direct current input signal, enabling efficient power delivery and flexible positioning between transmit and receive antennas, while also incorporating sensors for user data acquisition and unique ID management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If plane wave radiation coupling is used for wireless power transfer, then power can be transmitted over the air, but power coupling efficiency drops quickly with distance
Solution Approach 1:
The patent changes the operating parameters by using resonant frequency coupling between transmit and receive antennas. By tuning both antennas to the same resonant frequency, the system achieves enhanced power coupling efficiency at a distance compared to traditional inductive coupling, resolving the contradiction between wireless transfer capability and energy loss.
Solution Approach 2:
The system dynamically adjusts the resonant frequency of both transmit and receive antennas to maintain optimal coupling conditions. This dynamic tuning allows the system to adapt to varying distances and loading conditions, maintaining efficient power transfer over reasonable distances while minimizing energy loss.
2Productivity
If inductive coupling between transmit antenna and receive antenna is used, then multiple devices can be charged simultaneously, but spacing between antennas must be very close
Solution Approach 1:
The patent uses resonant frequency coupling to extend the effective coupling distance between transmit and receive antennas. By operating at resonant frequencies, the system maintains strong magnetic field coupling over larger spacings, enabling simultaneous charging of multiple devices placed at different locations within the coverage area without requiring millimeter-level proximity.
3Loss of energy
If resonant length antennas are used to improve coupling efficiency, then unintentional radiation can interfere with other systems
Solution Approach 1:
The patent confines the electromagnetic energy primarily to the near-field magnetic coupling region by using sub-wavelength resonant structures. The magnetic fields are concentrated in the local region between transmit and receive antennas, while far-field radiation is suppressed by keeping antenna dimensions much smaller than the operating wavelength, thus maintaining efficiency without causing interference to other systems.
Solution Approach 2:
The patent converts what would normally be radiative loss into useful near-field coupling by operating in the resonant near-field regime. The resonant structures that could potentially radiate are instead configured to create strong evanescent magnetic fields that decay rapidly with distance, turning potential interference into localized useful energy transfer.
4Ease of operation
If wireless power transmission is used, then charging becomes flexible and wireless, but efficiency is lower than wired transfer
Solution Approach 1:
The patent achieves high-efficiency wireless power transfer by operating at resonant frequencies and optimizing the quality factor (Q) of both transmit and receive antennas. This resonant coupling approach can achieve efficiency levels comparable to wired transfer by minimizing resistive losses and maximizing magnetic coupling, while retaining the flexibility and convenience of wireless operation.
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 enhances wireless power transfer efficiency and adaptability, allowing for reliable charging over reasonable distances and simultaneous charging of multiple devices with improved user data monitoring and tracking capabilities.
Implementation Method 1
The antenna is configured to receive a wireless power signal, and convert the wireless power signal to a direct current input signal
Implementation Method 2
A pulse modulator is configured to adjust an alternating current impedance of the wireless power receiver by modifying, based in part on the direct current input signal, a duty cycle of the pulse-width modulation signal
Implementation Method 3
Other approaches to wireless energy transmission techniques are based on inductive coupling between a transmit antenna embedded, for example, in a 'charging' mat or surface and a receive antenna (plus a rectifying circuit) embedded in the electronic device to be charged
Data Source
AI summary
A wireless power receiver includes a rectifier coupled to an antenna which is configured to receive a wireless power signal, and convert the wireless power signal to a direct current input signal. A direct current-to-direct current converter generates a direct current output signal based in part on the direct current input signal and a pulse-width modulation signal. A pulse modulator is configured to adjust an alternating current impedance of the wireless power receiver by modifying, based in part on the direct current input signal, a duty cycle of the pulse-width modulation signal to the direct current-to-direct current converter. A monitoring device is in communication with the rectifier and the pulse modulator. The monitoring device has one or more sensors and a unique user ID. The one or more sensors acquire user information selected from of at least one of, a user's activities, behaviors and habit information.