Controller Power-Down Circuit for Battery-Free Data Retention
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Solution Overview
Problem
Implementing power down functionality in complex process control systems in a cost-effective manner is challenging, particularly in retaining process values prior to power failure for reuse upon power up, without the use of batteries.
Innovation Solution
Utilizing a buffer capacitor to store energy for a power down sequence, a power voter to select the capacitor as an energy source during power failure, and non-volatile memory to retain process data, with logic circuitry coordinating data transfer during the power down sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional power down functionality is implemented in complex process control systems, then process data can be retained prior to power failure, but the system complexity and cost increase significantly
Solution Approach 1:
The patent extracts the power down functionality from the main controller and implements it as a separate, dedicated circuit module. This extracted module contains only the essential components (buffer capacitor, power voter, non-volatile memory, and logic circuitry) needed for data retention, eliminating the complexity of implementing full power down management within the complex process control system while maintaining the reliability benefit of data retention.
2Reliability
If batteries are used for power down functionality, then data can be retained during power failure, but the cost and device size increase
Solution Approach 1:
The patent replaces expensive, large-size batteries with a buffer capacitor that provides short-term energy storage sufficient for completing the power down sequence. The capacitor is charged during normal operation and discharged only when power failure occurs, providing the necessary energy for data transfer to non-volatile memory without the cost and size penalties of battery solutions. This disposable energy storage approach eliminates the need for expensive battery components while achieving the same data retention reliability.
3Reliability
If cyclic storage of data in non-volatile memory is implemented, then data can be retained, but process control execution tasks are hindered
Solution Approach 1:
The patent segments the data storage functionality by creating a dedicated power down circuit module that handles all non-volatile memory operations independently from the main process control execution paths. The logic circuitry within this module manages data transfer to and from non-volatile memory without interfering with the main controller's execution tasks. This segmentation allows cyclic storage operations to occur in the background while process control execution continues uninterrupted, maintaining both data retention reliability and execution productivity.
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
Enables cost-effective retention of process data using small, readily available components, ensuring unlimited data storage time and uninterrupted process control execution without batteries.
Implementation Method 1
at least one buffer capacitor for buffering sufficient energy to complete a power down sequence
Data Source
AI summary
A power down circuitry for a controller of a process control system includes at least one buffer capacitor for buffering sufficient energy to complete a power down sequence; a power voter configured to select the at least one buffer capacitor as energy source in response to detection of power failure; non-volatile memory for retaining process data following the detection of power failure; and logic circuitry configured to coordinate transfer of the process data to the non-volatile memory during the power down sequence.