Steel Sheet Temperature Control Using Feedforward and Feedback
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Solution Overview
Problem
Existing steel sheet temperature control methods face challenges in achieving both good responsiveness and eliminating steady-state deviations, particularly when dealing with variations in steel sheet sizes and annealing conditions, leading to control deviations and reduced responsiveness.
Innovation Solution
A steel sheet temperature control device and method that includes a sheet temperature measurement unit, furnace temperature measurement unit, influence coefficient calculation unit, control model setting unit, state variable/disturbance estimation unit, and furnace temperature control unit, which calculates and adjusts furnace temperature change amounts to minimize deviations and ensure responsive temperature control across multiple heating zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If feedforward control is used to improve responsiveness by significantly changing furnace temperature and fuel flow rate, then responsiveness is improved, but control deviation occurs due to model error
Solution Approach 1:
The patent combines feedforward control with feedback control to resolve the contradiction. The feedback control uses the measured steel sheet temperature to calculate correction amounts that compensate for model errors in the feedforward control. This ensures both responsiveness (from feedforward) and accuracy (from feedback correction) are achieved simultaneously.
Solution Approach 2:
The patent merges feedforward control and feedback control into a unified control system. The feedforward control provides rapid response based on predicted temperature changes, while the feedback control continuously corrects deviations caused by model inaccuracies. This combination allows the system to achieve both high responsiveness and high control accuracy.
2Reliability
If feedback control based only on outlet temperature measurement is used, then control accuracy is improved, but responsiveness is reduced due to large time constant
Solution Approach 1:
The patent applies preliminary action by using feedforward control to predict and preemptively adjust for temperature changes before they occur at the outlet. By calculating required temperature adjustments based on sheet characteristics and anticipated conditions, the system acts in advance, improving responsiveness without waiting for outlet temperature measurements.
Solution Approach 2:
The patent uses feedback control to maintain accuracy by continuously measuring outlet temperature and calculating correction amounts. This feedback mechanism ensures that despite the predictive nature of feedforward control, the system maintains high control accuracy by compensating for any deviations caused by model errors or unanticipated conditions.
3Speed
If furnace temperature is significantly changed in short period to improve responsiveness, then responsiveness is improved, but steady-state deviation occurs due to model error
Solution Approach 1:
The patent uses feedback control to eliminate steady-state deviations caused by significant furnace temperature changes. The feedback mechanism continuously monitors outlet temperature and calculates correction amounts that compensate for model errors, ensuring the system returns to and maintains the target temperature in steady-state conditions.
Solution Approach 2:
The patent applies the counterweight principle by using feedback correction to counterbalance the effects of model errors introduced by aggressive feedforward control. The feedback control acts as a counterweight that offsets deviations, allowing the system to make large temperature changes for responsiveness while maintaining steady-state stability.
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
The solution enables effective control of steel sheet temperature in a heating furnace with improved responsiveness and reduced steady-state deviations, ensuring the temperature converges to the target value quickly and accurately, even with disturbances.
Implementation Method 1
the temperature of a steel sheet is generally increased by radiation heating using a radiant tube
Data Source
AI summary
A steel sheet temperature control device including: a sheet temperature measurement unit; a furnace temperature measurement unit; an influence coefficient calculation unit; a control model setting unit that sets a control model; a state variable/disturbance estimation unit that estimates values of a state variable and a temperature disturbance variable of the control model at the same time; a furnace temperature change amount calculation unit that calculates a furnace temperature change amount of each of heating zones of a heating furnace under a constraint condition such that square sum of a deviation between a target value and the actual value of the temperature of the steel sheet at the outlet side of the heating furnace becomes minimum; and a furnace temperature control unit that controls a fuel flow rate used in each of the heating zones to achieve the calculated furnace temperature change amount.