本論文主要是針對扁鋼胚連鑄機之模液面控制系統進行穩定度之理論分析。在分析與研究扁鋼胚連鑄製程之模液面控制系統的過程中，首先針對此模液面控制系統中所使用的PLC程式進行解讀與分析，並建立其數學模式。接下來再建立從伺服放大器、伺服閥、液壓缸到模液面訊號輸出之整個模液面控制系統之數學模式，並根據此數學模式建立其Matlab模擬系統。於是便可以針對所建立之模液面控制系統穩定度的理論分析、以及動態響應的分析加以驗證。最後再考慮系統遭受各種可能的干擾情況之下，建立干擾的數學模式，並分析其對系統之動態響應、穩定度、及控制精密度所造成之影響。

The theoretical stability analysis of mold level control system for slab continuous casting machine is presented in this thesis. In the procedure of analyzing the stability of the mold level control system, the PLC program written for the control system is studied first in order to obtain the mathematical model of a PID controller. Then the mathematical models of servo-amplifier, servo-valve, electro hydraulic system to the output of mold level are established. A simulative control system using Matlab software is constructed in accordance with these mathematical models so that not only the results of stability analysis can be verified but also the dynamic response of controlled system can be studied. Finally, the effects of some potential disturbance on system’s dynamics, stability, and control accuracy are also analyzed.

目 錄

摘要

第一章 模液面控制系統簡介.......................................1

第二章 模液面控制模擬系統之建構.................................6
2.1 PLC Syatem...............................................6
2.1.1 Mold Reference Generarion................................6
2.1.2 Controller...............................................8
2.1.3 Cylinder Reference Generation...........................11
2.2 Servo-Amplifier System..................................14
2.3 Actuator................................................17
2.4 Plant Model.............................................18
2.4.1 Cylinder Position Convert to Slide Gate Position........18
2.4.2 Slide Gate Position to Flow Speed.......................19
2.4.3 Casting.................................................20
2.4.4 Flow Speed to Model Level...............................21
2.4.5 Sensor 3................................................22
2.5 動態響應之模擬..........................................22

第三章 系統穩定度的分析........................................24
3.1 內迴路系統穩定度分析....................................24
3.2 模液面控制系統穩定度分析................................27
3.3 變動PID控制器參數之動態響應分析.........................34

第四章 干擾影響的分析..........................................40
4.1 不作用區(Dead-Band).....................................40
4.2 液壓缸時間延遲(Time-Delay in Cylinder)..................42
4.3 阻塞現象(Clogging)......................................44
4.4 鋼液分配器中鋼液體積(或高度)之變化(Change of Molten Steel
Volumn in Tundish).....................................47
4.5 噴管時間延遲(SEN Time-Delay)............................50
4.6 引拔速度變化(Change of Casting Speed)...................53
4.7 模子截面積變化(Change in the Mold Cross Section Area)...54
4.8 模振效應(Mold Oscillation)..............................56

第五章 結論....................................................58

參考文獻.........................................................60


圖 表 目 錄


圖1.1 扁鋼胚連鑄機簡圖...........................................1
圖1.2 模液面控制系統簡化方塊圖...................................2
圖2.1 PLC System之簡化流程圖.....................................6
圖2.2 Oscillation示意圖..........................................8
圖2.3 微分控制器之控制方塊圖....................................10
圖2.4 含有saturation之數位積分器................................15
圖2.5 液壓缸實際位置與滑動閘門實際位置之線性關係示意圖..........18
圖2.6 液壓缸與滑動閘門之構造簡圖................................19
圖2.7 滑動閘門開口大小之誤差....................................20
圖2.8 滑動閘門開口示意圖........................................20
圖2.9 模液面高度訊號............................................23
圖3.1 模液面控制系統............................................24
圖3.2 非線性系統................................................25
圖3.3 非線性系統之Nyquist圖.....................................26
圖3.4 內迴路系統之Nyquist圖.....................................26
圖3.5 內迴路追蹤結果............................................27
圖3.6 k_h對時間之關係...........................................29
圖3.7 k_F對x_5大小之關係........................................29
圖3.8 模液面控制系統簡化圖......................................29
圖3.9 模液面控制系統之穩定範圍..................................34
圖3.10 模液面高度輸出............................................34
圖3.11 變動控制器參數時performance index p_i的變化...............36
圖3.12 變動k_p時e與integ(e^2)的變化..............................37
表3.1 變動k_p時e暫態響應的峰值與integ(e^2)的變化程度............37
圖3.13 變動k_i時e與integ(e^2)的變化..............................38
表3.2 變動k_i時e暫態響應的峰值與integ(e^2)的變化程度............38
圖3.14 變動k_d時e與integ(e^2)的變化..............................39
表3.3 變動k_d時e暫態響應的峰值與integ(e^2)的變化程度............39
圖4.1 不作用區效應影響之比較....................................41
圖4.2 g(jw)之Nyquist圖..........................................43
圖4.3 內迴路追蹤結果............................................43
圖4.4 液壓缸時間延遲影響之模液面高度............................44
圖4.5 阻塞現象對模液面之影響....................................46
圖4.6 精準度之比較..............................................46
圖4.7 鋼液分配器中鋼液高度變化對模液面之影響....................50
圖4.8 噴管時間延遲對模液面之影響................................52
圖4.9 引拔速度變化對模液面之影響................................54
圖4.10 模子截面積變化對模液面之影響..............................55
圖4.11 模振效應對模液面之影響....................................57

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