Controller Power-Down Circuitry Using Buffer Capacitors and NVM
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Implementing power down functionality in complex process control systems in a cost-effective manner is challenging, particularly in retaining process values during power failures without using batteries and ensuring seamless operation upon power restoration.
Innovation Solution
The power down circuitry employs a buffer capacitor to store energy for the 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, using logic circuitry to coordinate data transfer during the power down sequence, all without the need for batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batteries are used to retain process data during power failure, then data retention reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the energy storage function from batteries and implements it using buffer capacitors instead. The capacitors are charged during normal operation and discharge to provide power for data transfer to non-volatile memory during power failure, eliminating the need for batteries while maintaining data retention capability
Solution Approach 2:
The patent replaces expensive, complex battery systems with inexpensive capacitor-based energy storage. The capacitors provide sufficient energy for the critical power down sequence without requiring the complex chemistry and management systems of batteries, reducing both cost and device complexity
2Reliability
If cyclic storage of data in non-volatile memory is implemented, then data retention is improved, but process control execution is hindered
Solution Approach 1:
The system performs preliminary actions by continuously pre-charging buffer capacitors during normal operation and maintaining data in volatile memory. When power failure occurs, the pre-charged capacitors immediately provide energy for data transfer, eliminating the need for cyclic storage and allowing continuous process control execution
3Ease of manufacture
If buffer capacitors are used instead of batteries, then device cost is reduced, but energy storage capacity is limited
Solution Approach 1:
The patent applies partial action by providing enough energy storage capacity to complete the critical power down sequence (data transfer to non-volatile memory) rather than providing enough energy for full system operation. This partial energy provision is sufficient to achieve the goal of data retention while using inexpensive capacitors instead of expensive batteries
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
This approach allows for cost-effective implementation using readily available components, ensures unlimited data retention time, and maintains system operation by bridging voltage dips, thus preserving process data integrity and continuity.
Implementation Method 1
buffer capacitor for buffering sufficient energy to complete a power down sequence
Implementation Method 2
non-volatile memory for retaining process data following the detection of power failure
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There is provided power down circuitry for a controller (102) of a process control system. The power down circuitry comprises: at least one buffer capacitor (204) for buffering sufficient energy to complete a power down sequence; a power voter (206) configured to select the at least one buffer capacitor as energy source in response to detection of power failure; non-volatile memory (214) for retaining process data following the detection of power failure; and logic circuitry (208) configured to coordinate transfer of the process data to the non-volatile memory during the power down sequence.