Flow Rate Valve Startup Control for Fast Response Without Overshoot
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Solution Overview
Problem
Existing flow rate control devices experience slow response and overshoot when starting from a flow rate of 0 L/min due to valve characteristics and small PID deviations, leading to inefficient fluid outflow.
Innovation Solution
The flow rate control device incorporates a low flow rate rapid valve opening function that forcibly opens the flow rate regulating valve from fully closed to a designated opening degree at the start of control, and an overshoot suppression function that maintains standby until a preset time or threshold is reached, preventing overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PID control is used with small valve opening deviations, then control precision is maintained, but response speed becomes slow when starting from zero flow rate
Solution Approach 1:
The control method dynamically adjusts the valve opening strategy based on the current state: when the valve is fully closed and flow rate is zero, it rapidly opens to a predetermined opening to achieve fast response; when the valve is already open, it uses small PID deviations for precise control. This dynamic adaptation resolves the contradiction between fast response and control precision.
Solution Approach 2:
The invention changes the control parameters based on operating conditions: it switches between rapid opening mode (for fast response from closed state) and PID control mode (for precise control when already open). This parameter change allows the system to optimize for either speed or precision depending on the current state, resolving the contradiction.
2Speed
If the valve is rapidly opened to improve response, then flow rate increases quickly, but overshoot occurs
Solution Approach 1:
The system performs preliminary action by opening the valve to a predetermined opening degree rather than fully opening it, which prepares the system for fast response while preventing excessive flow. This preliminary controlled opening avoids the need for large subsequent corrections that would cause overshoot.
Solution Approach 2:
The invention uses feedback from the flow rate meter to monitor the actual flow rate and compare it with the target value. This feedback mechanism allows the system to detect when the flow rate approaches the target and make appropriate adjustments, preventing overshoot while maintaining fast response.
3Manufacturing precision
If the valve remains fully closed at zero flow rate, then control precision is maintained, but response time increases
Solution Approach 1:
The system performs preliminary action by opening the valve to a predetermined opening degree when the command is received, rather than waiting for PID control to gradually open it. This preliminary action significantly reduces response time while the subsequent PID control maintains precision.
Solution Approach 2:
The control method dynamically switches between rapid opening mode (when valve is closed) and PID control mode (when valve is open). This dynamic transition allows the system to prioritize speed when needed and precision when needed, resolving the contradiction between response time and control precision.
Data Source
AI summary
A flow rate control device capable of suppressing overshoot while improving responsiveness at the beginning of flow rate control includes: a flow rate meter that measures a flow rate of a fluid flowing through a flow path; a flow rate regulating valve that regulates the flow rate of the fluid flowing through the flow path; and a control part that controls an opening degree of the flow rate regulating valve based on a measurement result of the flow rate meter, the flow rate control device has: a low flow rate rapid valve opening function that accelerates an outflow of the fluid by forcibly opening the opening degree of the flow rate regulating valve from fully closed degree to a designated opening degree when the opening degree of the flow regulating valve is fully closed and a flow rate control is started; and an overshoot suppressing function that is used for suppressing the overshoot by making the flow rate control stand by until a preset standby time or a preset flow rate threshold is reached immediately after the low flow rate rapid valve opening function works.