Trickle-Charged RFID Device Power Management
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Solution Overview
Problem
Conventional active or semi-passive RFID devices have limited battery life due to non-rechargeable batteries, which restricts their operational duration, especially in applications like tracking ocean-going containers, as recharging from weak RF fields is inefficient and rechargeable batteries require significant potential differences.
Innovation Solution
Implementing a trickle-charged RFID device with a power harvester and intermediate storage, such as super-capacitors, to collect and store unused power from wireless interrogator signals, allowing for periodic recharging of a rechargeable battery when the threshold is reached, extending the device's operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If rechargeable batteries are used in RFID devices, then battery life can be extended through recharging, but significant potential difference is required which cannot be obtained from weak RF fields
Solution Approach 1:
The power storage system is segmented into two distinct components: a primary storage device (rechargeable battery) for long-term energy storage and an intermediate storage device (capacitor) for temporary energy accumulation. This segmentation allows the system to overcome the potential difference barrier by accumulating small amounts of energy incrementally in the intermediate storage device before transferring to the primary storage device.
Solution Approach 2:
An intermediate storage device (capacitor) is introduced as a mediator between the power harvester and the rechargeable battery. This intermediary component can store small amounts of harvested energy and release it when sufficient potential difference is accumulated, enabling the rechargeable battery to be charged from weak RF fields that would otherwise be insufficient.
2Use of energy by moving object
If energy is harvested from existing RF fields, then power can be obtained for recharging, but the fields are very weak and insufficient to recharge batteries
Solution Approach 1:
The system performs preliminary energy accumulation by continuously harvesting weak RF energy and storing it in the intermediate storage device before attempting to charge the primary storage device. This preliminary action allows the system to build up sufficient energy and potential difference over time, transforming weak continuous energy input into effective charging capability.
Solution Approach 2:
The charging process operates periodically: the intermediate storage device accumulates energy from the power harvester during periods when sufficient potential difference is not available, and then transfers energy to the primary storage device when the threshold is reached. This periodic action enables effective charging despite the weak and intermittent nature of harvested RF energy.
3Duration of action of moving object
If larger capacity batteries are used, then operational duration is extended, but batteries deteriorate relatively quickly and reach lifetime limits
Solution Approach 1:
The system implements continuous energy harvesting and periodic recharging, ensuring that the primary storage device is continuously topped up with energy from the intermediate storage device. This continuous useful action prevents deep discharge cycles and maintains the battery in a healthier state, extending its operational lifespan beyond what a single large-capacity battery could achieve.
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
Significantly extends the battery life of RFID devices by harnessing and storing unused power from RF fields, enhancing their operational lifespan and versatility in tracking and monitoring applications.
Implementation Method 1
a power harvester connected with the main antenna to obtain power from the wireless interrogator signals
Implementation Method 2
The intermediate storage device can collect trickle flows of unused, harvested power that is obtained from wireless interrogator signals
Implementation Method 3
The primary storage device can include a rechargeable battery
Data Source
AI summary
A trickle-charged RFID device includes a main antenna receiving wireless interrogator signals from one or more RFID readers, a power harvester connected with the main antenna to obtain power from the wireless interrogator signals, and an intermediate storage device connected to the power harvester to collect trickle flows of unused power harvested from wireless interrogator signals received by the RFID device that lack an inquiry for the device. The RFID device further includes a primary storage device, into which the intermediate storage device discharges its collection of trickle flows of unused power when the collection reaches a predetermined threshold level, which recharges power lost from the main storage device. The intermediate storage device can include one or more capacitors including super-capacitors, and the main storage device can include a rechargeable battery, such that the effective life of the main storage device is extended from the collected trickle flows.