模糊控制器在主動磁浮軸承系統的應用

Active Magnetic Bearing System Equipped With a Fuzzy Logic Controller

本文提出一種智慧型控制方法應用於主動式磁浮軸承系統，此方法利用模糊邏輯控制器進行此磁浮系統的懸浮定位控制，令磁浮軸承之定子與轉子之間維持固定的氣隙。由於磁浮軸承本質上為不穩定的系統，且通入之電流與磁力之間為高度非線性，工業界目前仍採用傳統的比例－積分－微分控制器，而模糊邏輯控制器利用近似人類感知與推理的能力，儼然成為一套解決不確定問題的數學工具，因此本研究針對磁浮軸承系統設計一套閉回路模糊控制器，首先建構磁浮軸承多輸入多輸出之數學模型，再依此模型設計模糊控制器輸出入變數的歸屬函數及規則，模擬結果顯示系統的響應具有滿意的控制性能，無超越量、零穩態誤差及相當短的上升時間，所提的控制器可應用於具外界干擾之磁浮軸承，且轉軸可在寬廣的位置範圍內操作。

This paper proposes an intelligent control method for positioning an active magnetic bearing (AMB) system, by using emerging fuzzy logic controller (FLC) approaches. An AMB system depends on controlling the air gap between the stator and the rotor. In practice, no precise mathematical model can be established because the rotor displacement in an AMB system is inherently unstable, and the relationship between the current and electromagnetic force is highly nonlinear. Nearly all industrial applications of AMBs are still based on conventional proportional-integral-derivative or proportional-derivative controllers. Recently, fuzzy logic has been used as a mathematical tool for addressing the uncertainties in human perception and reasoning. It also provides a framework for applying approximate human reasoning capabilities to knowledge-based systems. This study designed a closed-loop decentralized FLC for an AMB system. The control algorithm was numerically evaluated to construct a multiple-input multiple-output mathematical model of the controlled system. The membership functions and rule design of the FLC were based on the mathematical model of an AMB system. The simulation results for the AMB system indicated that the system responded by demonstrating satisfactory control performance without overshoot, maintaining a zero-error steady state, and exhibiting a short rise time. The proposed controller can be feasibly applied to AMB systems exhibiting various external disturbances and the FLC with capacities operates effectively in a wide range of shaft positions.