Hybrid PI Feedback Control for Fast Stable Pressure Regulation
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Solution Overview
Problem
Existing feedback control systems for pressure control in super-critical fluid chromatography and extraction face instability and low responsivity due to the need for complex analog circuits and time-consuming digital processing, respectively.
Innovation Solution
A hybrid feedback control apparatus that performs proportional control using an analog electric circuit and integral control through digital processing, effectively combining the strengths of both methods to achieve high stability and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an analog scheme is used for PI control, then responsivity is improved, but device complexity increases and control stability deteriorates
Solution Approach 1:
The patent divides the PI control function into two separate parts: P control is implemented using an analog circuit for rapid response, while I control is implemented using a digital signal processor for stability and simplicity. This segmentation allows each component to be optimized independently, resolving the contradiction between responsivity and device complexity.
2Device complexity
If a digital scheme is used for PI control, then device complexity is reduced, but responsivity deteriorates due to A/D conversion, D/A conversion, and digital processing time
Solution Approach 1:
The patent segments the control functions by assigning P control to analog circuitry which provides immediate response without conversion delays, while I control is handled by digital processing. This eliminates the responsivity penalty that would occur if the entire PI control were digital, as the time-critical P component operates in the analog domain.
3Ease of manufacture
If a purely digital PI control scheme is used, then ease of implementation is improved, but control stability deteriorates
Solution Approach 1:
The patent implements P control using analog circuits which inherently provide stable and predictable behavior for the proportional response, while I control is implemented digitally where it can be easily programmed and adjusted. This segmentation allows the stable analog P component to handle immediate corrections while the flexible digital I component handles long-term error elimination.
Data Source
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AI summary
A feedback control apparatus includes: a detector configured to detect an output value based on a controlled object; a P control circuit including a differential amplifier circuit and an analog circuit, the differential amplifier circuit being configured to receive a detection value of the detector and a target value, the analog circuit being configured to output a P control component VP to an output of the differential amplifier circuit; an I control unit configured to output an I control component VI by integrating a deviation of the detection value from the target value by digital processing; and a driver element configured to be driven based on the P control component VP from the P control circuit and the I control component VI from the I control unit to control the controlled object.