- 學位論文
繼電器回授系統識別之即時自適應PID控制器應用於滿液式變頻冰水主機
Real-Time Self-Tuning PID controller of Relay Feedback System Identification Applied in Flooded VSD Chiller
摘要
若想要有準確的控制的表現，就必須仰賴好的系統識別和控制方法。 實務上，受控系統大多為非線性系統，難以用數學函數或物理模型來表示受控體，因此使用受控體的近似模型來控制。近似模型是對非線性系統的簡化和近似，近似模型的準確性，會影響控制器的控制效果。 為了讓自適應PID控制器能使用於各式冰水主機，進而建構出一種可攜式的自適應PID控制器，本文利用基於繼電器回授之系統識別方法找出滿液式變頻冰水主機的近似模型參數，再結合自適應PID控制器對冰水主機進行控制。 為達到自動控制整定參數的目的，整個過程分為系統識別和PID自整定兩部分。利用繼電器回授測試得到的系統資訊，藉以得到系統近似模型參數。對於系統鑑別後之模型，藉由控制參數規則庫來進行線上PID控制器參數調整，使受控系統有自我調節與追蹤之功能，達到預設的理想控制效果。 利用繼電器回授系統識別可以比步階響應法更快計算出模型參數，而其所計算出的模型參數能使PID控制比步階響應法更快達目標值並穩定，針對控制目標值具有±0.1℃的準確性。
並列摘要
If accurate control performance is expected, excellent system identification and control method are needed. In practically, most of those controlled systems are non-linear system. It’s hard to represent plant by mathematical function or physical model, so it has to be controlled by a plant’s approximation. An approximation is the simplicity and similarity to non-linear system. The accuracy of it will affect the efficiency of controller. In order to make the adaptive PID controller which can be used by all type of chillers, the study uses the system identification method with relay feedback to identify the similar model parameter of VSD Chiller and control the chiller with the adaptive PID controller. All the processes are divided into two steps of systematic identification and the self-tuning for PID to reach the aim that tunes parameters by automatic control. This research utilizes the feedback test of relay’s system information to get the systematic parameter of approximation. And the model after system is identified. the controller adjusts its PID parameter online by the rule base of parameters. The relay feedback system identification can be faster than the step response method to calculate the model parameters and it makes PID control faster and more stable than the step response method to target the set-point with accuracy of ±0.1℃