Free Piston Mover Stroke Control to Prevent Current Saturation
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Solution Overview
Problem
Existing control methods for Free Piston Movers (FPMs) in Linear Power Systems (LPS) fail to adequately adjust control parameters for future strokes, leading to saturation and suboptimal performance due to inadequate maintenance of Current Demand Control Margin and failure to compensate for system changes over time.
Innovation Solution
A control method involving a Future-Stroke Controller that generates and transmits a Control Parameter Set to an In-Stroke Controller, including a Target Control Variable Function, Stroke Threshold Function, Feed Forward Current Function, and Feedback Terms Function, to adapt control parameters for future strokes, ensuring a sufficient Current Control Margin and compensating for system changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing control methods are used for Free Piston Movers, then the control system structure is simple, but the system performance becomes suboptimal due to saturation and inability to compensate for system changes over time
Solution Approach 1:
The control system is segmented into two distinct controllers: a Future-Stroke Controller that generates control parameter sets in advance, and an In-Stroke Controller that executes real-time control during stroke operation. This segmentation allows complex predictive control functions to be separated from real-time execution, improving system performance while managing complexity through functional division
Solution Approach 2:
The Future-Stroke Controller performs preliminary actions by generating control parameter sets (including Target Control Variable Functions, Stroke Threshold Functions, Feed Forward Current Functions, and Feedback Terms Functions) before the stroke begins. This advance preparation ensures optimal control parameters are ready, preventing saturation and enabling compensation for system changes without compromising real-time response
2Productivity
If control parameters are not adjusted for future strokes, then the control system operates simply, but the Current Demand Control Margin becomes insufficient leading to saturation
Solution Approach 1:
The control system incorporates feedback mechanisms where the Future-Stroke Controller continuously monitors system state and adjusts control parameter sets for upcoming strokes based on actual performance. The Feedback Terms Function specifically addresses Current Demand Control Margin maintenance by learning from past stroke outcomes and modifying future control parameters to prevent saturation
Solution Approach 2:
The system dynamically changes control parameters between strokes through the Control Parameter Set, which includes Time Varying Target Control Variable Functions and Stroke Threshold Functions. These parameter changes enable the system to adapt to varying operating conditions, maintain efficiency, and prevent Current Demand Control Margin depletion without requiring complex real-time adjustments during stroke execution
3Manufacturing precision
If the FPM motion is not precisely controlled, then the control system is simpler, but the system fails to achieve optimal performance in efficiency, repeatability, precision, and reliability
Solution Approach 1:
The control system employs dynamic control parameter sets that are specifically tailored to each stroke's requirements. The Time Varying Target Control Variable Functions and Stroke Threshold Functions create dynamic control profiles that adapt to the FPM's motion characteristics, achieving high precision and repeatability while managing complexity through stroke-specific parameter optimization rather than universal complex control logic
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 improves efficiency, reduces vibration, shortens start-up times, extends operating life, reduces emissions, and enhances fuel flexibility in FPLG applications by continuously adapting control parameters to maintain optimal system performance.
Implementation Method 1
there is a Linear Electro-Mechanical System and a Linear Thermo-Fluidic System which are coupled through the linear motion of the Free Piston Mover
Implementation Method 2
The pressure of working fluid within the working chamber produces a force acting upon the piston
Implementation Method 3
the addition or removal of heat to/from the working chamber as a result of heat transfer to/from the working chamber walls
Data Source
AI summary
A method of controlling a Free Piston Mover, the method comprising the steps of: generating a Control Parameter Set for closed loop control of a Target Control Variable, this set comprising a Target Control Variable Function together with one or more of: a Stroke Threshold Function; a Feed Forward Current Function; a Feedback Terms Function; Control Parameter Set Transition Conditions; transmitting the Control Parameter Set to an In-Stroke Controller in advance of the start of a Stroke to be controlled; modifying one or more of the constituents of the Control Parameter Set for any Future Stroke of the Free Piston Mover using a Future-Stroke Controller; and transmitting the modified Control Parameter Set to the In-Stroke Controller for the control of any Future Stroke.