Dynamic Limiter for Pressure Control Valve Overshoot
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Solution Overview
Problem
Existing pressure control devices in semiconductor manufacturing face challenges in maintaining responsiveness and stability across varying set pressure values, leading to overshoot and ringing issues, especially when the PID coefficient is set high to shorten response time, and the upper limit value of the pressure control valve's open degree is fixed, resulting in inconsistent response times and reduced yield.
Innovation Solution
A pressure control device with a limiter part that sets a tolerance for the open degree operated amount based on the set pressure value, allowing the upper limit value to change accordingly, preventing overshoot and maintaining consistent response time by controlling the pressure control valve at the set upper limit value when the open degree operated amount exceeds it, and prioritizing stability at lower set pressure values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large PID coefficient is set to shorten response time, then responsiveness is improved, but stability deteriorates causing overshoot and ringing
Solution Approach 1:
The upper limit value of the open degree operated amount is made dynamically adjustable based on the set pressure value. The limiter part changes the upper limit value according to the magnitude of the set pressure value, allowing the system to adapt its constraints dynamically. This resolves the contradiction by enabling high responsiveness (through large PID coefficients) while maintaining stability (through adaptive upper limits that prevent excessive valve opening).
Solution Approach 2:
The invention changes the parameter of the upper limit value based on the set pressure value. When the set pressure value is large, a larger upper limit value is permitted; when the set pressure value is small, a smaller upper limit value is applied. This parameter adaptation allows the system to achieve both fast response and stable control across different operating conditions.
2Device complexity
If the upper limit value of open degree operated amount is fixed, then device complexity is reduced, but adaptability deteriorates across different set pressure values
Solution Approach 1:
The limiter part introduces dynamic adaptability by adjusting the upper limit value based on the set pressure value magnitude. This dynamic adjustment mechanism maintains relatively simple device structure while significantly improving adaptability across different pressure control scenarios.
3Speed
If a large open degree operated amount is input to shorten response time, then responsiveness is improved, but manufacturing precision deteriorates due to overshoot
Solution Approach 1:
The limiter part applies preliminary anti-action by pre-establishing an upper limit on the open degree operated amount based on the set pressure value. This prevents the pressure control valve from opening excessively in the first place, thereby preventing overshoot and ringing before they can occur. The system proactively constrains the valve operation to maintain precision while still allowing fast response.
Data Source
AI summary
To provide a pressure control device that can prevent ringing and overshoot without changing gain even with a high gain setting, can quickly change pressure to a steady state even with a large set pressure value, and can equalize the time required from an initial to steady state regardless of the set pressure value, a valve control part is provided that includes an open degree operated amount output part that outputs an open degree operated amount based on a measured pressure value and a set pressure value, and a limiter part that sets an upper limit value of the open degree operated amount according to the set pressure value and that controls a pressure control valve by the open degree operated amount of the upper limit value when the open degree operated amount exceeds the upper limit value.