Autonomous RIS Rectifier Switching for RF Energy Harvesting
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Solution Overview
Problem
Reconfigurable intelligent surfaces (RIS) consume non-negligible power for manipulating phase shifts, despite being passive, and there is a need for a more efficient energy harvesting solution to reduce or eliminate external power requirements.
Innovation Solution
Integration of energy harvesting antennas and a dual-mode rectifier circuit with a power-dependent switch that automatically switches between low and high power modes, coupled with a dual-battery system for efficient energy storage and distribution, allowing the RIS to be self-sufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If passive reflection is used, then power consumption is reduced, but phase shift manipulation capability is limited
Solution Approach 1:
The system harvests energy from the incident electromagnetic signals itself to power the phase shift manipulation, making the RIS self-sufficient without external power sources while maintaining full phase shift control capability across all unit cells
2Use of energy by stationary object
If energy harvesting antennas are integrated, then external power requirements are reduced, but device complexity increases
Solution Approach 1:
The RIS surface serves dual functions: reflecting electromagnetic signals for communication and harvesting energy from the same signals to power the system. The unit cells are designed to perform both signal manipulation and energy harvesting simultaneously, reducing the need for separate components
Solution Approach 2:
The patent combines the signal reflection function and energy harvesting function into a single integrated system. The rectifier circuit is directly integrated with the unit cells, merging the communication and power harvesting functionalities into one cohesive structure
3Loss of energy
If dual-mode rectifier circuit is used, then energy conversion efficiency is improved, but circuit complexity increases
Solution Approach 1:
The rectifier circuit dynamically switches between low-power mode and high-power mode based on the received signal strength. The system adapts its operation mode in real-time to optimize energy conversion efficiency for varying signal conditions without requiring manual intervention
Solution Approach 2:
The patent changes the operational parameters of the rectifier circuit based on input power levels. When the received signal is strong, the high-power mode is activated with different rectification parameters; when the signal is weak, the low-power mode engages with optimized parameters for low-input scenarios, thereby maintaining high efficiency across all power levels
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 achieves high energy conversion efficiency across a wide range of signal strengths, enabling the RIS to operate autonomously with minimal external power consumption, enhancing network energy efficiency and reducing reliance on external power sources.
Implementation Method 1
a first port of a multiport circulator device, and the second port coupled to a power-dependent switch that self-actuates into a closed state at a defined high RF power level
Implementation Method 2
a first port of a multiport circulator device, and the second port coupled to a power-dependent switch
Data Source
AI summary
The technology described herein is directed towards a reconfigurable intelligent surface (RIS) that harvests RF energy from incoming signals based on energy harvesting antennas and associated energy harvesting circuitry. At the same time RIS elements (unit cells) redirect the incoming signals towards a predetermined direction. The harvested energy is combined and converted to DC power using a harvesting circuit. In one implementation, a dual-mode energy harvesting circuit employs a higher power rectifier subcircuit and a lower power rectifier subcircuit, with a multiport circulator and switch that self-actuates to use one or the other rectifier subcircuit based on the combined RF input power captured by the energy harvesting antennas. A multiple battery approach is described, in which one battery is charging based on the converted DC power, another, previously-charged battery is powering the reconfigurable intelligent surface components.