Multi-Capacitor RF Energy Harvesting for Stable Tag Power
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Solution Overview
Problem
Electronic tags often fail to receive an optimal RF signal for energy harvesting, leading to insufficient power for consistent operation, as the received RF signal may not provide the minimum operational voltage required for circuitry, resulting in intermittent functionality.
Innovation Solution
Implementing a multi-capacitor system where a larger capacitor is initially charged to a first voltage level based on the RF signal strength, and the charge is transferred to a smaller capacitor to generate a higher voltage level sufficient for circuit operation, with an efficient voltage monitor managing the charging process to ensure consistent power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single capacitor is used for energy storage in electronic tags, then the device complexity is reduced, but the reliability of power supply becomes insufficient when RF signal strength is suboptimal
Solution Approach 1:
The energy storage system is divided into two separate capacitors (first capacitor and second capacitor) with different capacitance values. The first capacitor has larger capacitance for bulk energy storage, while the second capacitor has smaller capacitance for voltage boosting. This segmentation allows each capacitor to serve a specific function, improving overall power supply reliability without requiring a single complex high-voltage capacitor.
Solution Approach 2:
The oscillator circuit acts as an intermediary mechanism that transfers energy from the first capacitor to the second capacitor. When the first capacitor is charged to a first voltage level, the oscillator generates oscillations that are rectified to charge the second capacitor to a higher second voltage level. This intermediary transfer mechanism enables voltage boosting without direct connection between the capacitors and the load.
2Power
If a larger capacitor is charged to a higher voltage to provide sufficient power, then the power availability improves, but the risk of overvoltage damage and energy loss increases
Solution Approach 1:
Different voltage levels are assigned to different capacitors based on their specific functions. The first capacitor operates at a lower first voltage level suitable for bulk storage, while the second capacitor operates at a higher second voltage level suitable for powering the load. This local quality differentiation ensures that no single capacitor is subjected to excessive voltage stress, reducing energy loss and damage risk.
Solution Approach 2:
The system dynamically changes voltage parameters through the oscillator-based energy transfer mechanism. When the first capacitor reaches the first voltage level, the oscillator activates to transfer energy and charge the second capacitor to the higher second voltage level. This parameter change approach allows the system to achieve high voltage for power availability while maintaining safe operating conditions during the charging phase.
3Productivity
If the electronic tag operates with intermittent power supply, then the device complexity is reduced, but the productivity and consistent operation are compromised
Solution Approach 1:
The first capacitor is charged in advance to the first voltage level before the second capacitor is charged. This preliminary action ensures that energy is stored in advance during periods when RF signal strength is sufficient, allowing the second capacitor to be charged to the required voltage level for consistent operation. The voltage monitor continuously monitors voltage levels to trigger charging operations at appropriate times.
Solution Approach 2:
The voltage monitor provides continuous feedback on the voltage levels of both capacitors and the load requirements. When the first capacitor reaches the first voltage level, the monitor triggers the oscillator to transfer energy to the second capacitor. When the second capacitor reaches the second voltage level, the monitor switches the load connection to maintain stable operation. This feedback mechanism ensures consistent productivity without requiring complex manual control.
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 multi-capacitor system ensures consistent and extended functionality of electronic tags by providing a stable power supply, even with suboptimal RF signal conditions, enhancing energy harvesting efficiency and reliability.
Implementation Method 1
The first rectifier is coupled to the first capacitor
Implementation Method 2
generating an oscillating signal based on the first voltage at the first capacitor
Implementation Method 3
rectifying the oscillating signal to produce a second voltage at a second capacitor
Implementation Method 4
storing the collected energy with a capacitor
Data Source
AI summary
An apparatus is disclosed for multi-capacitor energy harvesting. In example aspects, the apparatus includes energy storage including a first capacitor and a second capacitor. The apparatus also includes an energy harvester including at least one rectifier and one or more switches. The switches can be controlled to initially charge the first capacitor and subsequently charge the second capacitor.