RF Energy Harvester With Dual Capacitors for Stable DC Output
Solution Overview
Problem
Existing energy harvesters inefficiently convert and store Radio Frequency (RF) energy from 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 stabilizes voltage using a storage output capacitor, controlled by a control unit to efficiently transfer energy from the pre-storage to the storage capacitor, creating a stable voltage reference for DC-DC conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If RF energy is rectified and stored in a pre-storage capacitor, then RF energy conversion is achieved, but the voltage is unstable and insufficient for DC-DC converter operation
Solution Approach 1:
The energy storage system is divided into two separate capacitors: a pre-storage capacitor for initial RF energy accumulation and a storage output capacitor for stable voltage provision. This segmentation allows each capacitor to serve its specific function optimally, resolving the contradiction between energy conversion and voltage stability.
Solution Approach 2:
The pre-storage capacitor acts as an intermediary between the rectifier and the storage output capacitor. It temporarily holds rectified RF energy and transfers it to the storage output capacitor, enabling stable voltage operation for the DC-DC converter while maintaining efficient RF energy conversion.
2Device complexity
If a single capacitor is used for energy storage, then device complexity is reduced, but energy transfer efficiency and voltage stability deteriorate
Solution Approach 1:
The storage system is segmented into two capacitors with distinct roles: pre-storage capacitor for RF energy accumulation and storage output capacitor for stable voltage delivery. This segmentation improves energy transfer efficiency and voltage stability despite increased component count.
Solution Approach 2:
The pre-storage capacitor performs preliminary energy accumulation from RF signals before transferring to the storage output capacitor. This preliminary action ensures that the storage output capacitor receives energy in optimal quantities, improving overall transfer efficiency and stabilizing output voltage.
3Stability of the object's composition
If the storage output capacitor has high capacitance value, then voltage stability improves, but the energy transfer control becomes more challenging
Solution Approach 1:
The control unit continuously monitors the voltage across the pre-storage capacitor and adjusts the energy transfer timing to the storage output capacitor accordingly. This feedback mechanism ensures optimal charging cycles, maintaining stable voltage output despite the high capacitance value of the storage output capacitor.
Solution Approach 2:
The energy transfer process is made dynamic through controlled timing adjustments. The control unit adapts the transfer timing based on real-time voltage conditions, allowing the system to maintain stability with high-capacitance storage while responding to varying RF energy input conditions.
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 efficiently converts and stores RF energy, providing a stable voltage reference for DC-DC converters, eliminating the need for batteries in devices.
Implementation Method 1
a rectifier comprising a pre-storage capacitor, wherein said rectifier is arranged to rectify said incoming incident RF energy thereby storing said RF energy into said pre-storage capacitor
Implementation Method 2
an energy transfer unit comprising a storage output capacitor, wherein a capacitance value of said storage output capacitor is higher than a capacitance value of said pre-storage capacitor
Data Source
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).