RF Energy Harvester Circuit for Staged Voltage Boost and Storage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing energy harvesters inefficiently convert and store Radio Frequency (RF) energy associated with RF signals, necessitating the use of batteries for device operation.
Innovation Solution
An energy harvester with a rectifier, pre-storage capacitor, and energy transfer unit that includes a storage output capacitor, controlled by a control unit to efficiently transfer energy from the pre-storage capacitor to the storage output capacitor, forming a stable voltage reference point for DC-DC converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional rectifier circuits are used to harvest RF energy, then the circuit can operate at standard supply voltages (e.g., 3.3V or 5V), but the harvested energy is insufficient to charge capacitors with higher operating voltages (e.g., 10V or 15V) required by certain sensors and transmitters
Solution Approach 1:
The energy transfer unit is divided into multiple stages, each with its own voltage multiplication capability. The first energy transfer unit includes a first switch, first inductor, and first capacitor, while the second energy transfer unit includes a second switch, second inductor, and second capacitor. This segmentation allows progressive voltage multiplication from the pre-storage capacitor through multiple stages to achieve the high output voltage required by the load.
Solution Approach 2:
The pre-storage capacitor is charged to an intermediate voltage level before the final energy transfer to the output capacitor. The control unit controls the switches to transfer energy from the antenna to the pre-storage capacitor in advance, preparing the energy at an intermediate voltage state before the final voltage multiplication stage. This preliminary energy storage at intermediate voltage enables the subsequent high-voltage output stage to function effectively.
2Quantity of substance
If the storage output capacitor has a higher value than the pre-storage capacitor to store more energy, then the energy storage capacity increases, but the circuit complexity and component requirements increase
Solution Approach 1:
The control unit dynamically controls the switches to manage energy transfer between capacitors based on real-time conditions. The system transitions between different operational states: charging the pre-storage capacitor from the antenna, transferring energy from pre-storage to output capacitor, and managing the discharge to the load. This dynamic control allows the system to achieve high energy storage capacity without requiring permanently complex circuit configurations, as the complexity is managed through temporal sequencing rather than spatial complexity.
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 solution enables efficient conversion and storage of RF energy, eliminating the need for batteries by creating a stable voltage reference point for DC-DC converters, enhancing energy harvester efficiency and reliability.
Implementation Method 1
a rectifier (5) comprising a pre-storage capacitor (4), wherein said rectifier is arranged to rectify said incoming RF energy (3), storing the RF energy into the pre-storage capacitor (4)
Implementation Method 2
an energy transfer unit (6) comprising a storage output capacitor (8)... the energy transfer unit is arranged to transfer said energy from the pre-storage capacitor into the storage output capacitor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An energy harvester (RF) to convert incident radio frequency, RF, energy associated with an RF signal to direct current energy comprises a rectifier (5) comprising a pre-storage capacitor (4), wherein said rectifier is arranged to rectify said incoming RF energy (3), storing the RF energy into the pre-storage capacitor (4), followed by an energy transfer unit (6) comprising a storage output capacitor (8), the value of the storage output capacitor (8) is higher than the value of the pre-storage capacitor (4), the energy transfer unit is arranged to transfer said energy from the pre-storage capacitor into the storage output capacitor including a control unit (2).