本論文主要針對感應馬達在中低轉速下以直接轉矩控制方法於中轉速下之控制性能探討與電磁轉矩不足之改善。
直接轉矩控制方法之優點在於，不需經由複雜的數學作解耦合的動作。因此，其架構簡單與且易於實現的優點，非常適用於轉矩響應快速之場合；此外，控制計算過程中，亦只需參數中的定子電阻，使得系統受溫升效應的影響大幅減少，進而提升其強健性。
傳統直接轉矩控制方法中，雖只需定子電阻作為估算之參數，但由於馬達經長時間運轉或加載運轉而造成溫度上升，此時內部參數也會因溫升效應的關係而有所改變，產生參數的漂移或內部的磁飽和現象，使得馬達參數不再維持定值，進而導致定子磁通向量於空間位置之估測產生誤差，而選擇不正確的電壓控制向量，無法建立有效的轉矩，而產生轉矩不足之現象。
因此，本論文針對傳統直接轉矩控制方法於低轉速時，因定子電阻所導致磁通估算的問題，採用以低通濾波器回授路徑上，改善磁通估算的精確度，進而改善馬達於低速運轉時之電壓切換策略。
論文中所進行的研究，經由MATLAB作為模擬之根據，並以硬體實際測試結果作為驗證，以佐證出直接轉矩之感應馬達驅動系統，適用於低轉速直接驅動之場所，藉以改善傳統感應馬達驅動器低轉速扭力不足之缺點。
此外，對於傳統比例積分速度控制器所存在的缺點，如：積分飽和的現象與控制器輸出增益飽和的情形，實現一新型可變結構-比例積分速度控制器，以有效改善因飽和現象，所造成速度響應的影響。

The thesis presents a new direct torque control (DTC) structure to improve the drawbacks of the conventional DTC in high-performance ac induction motor drivers which operate during the low speed range. The proposed algorithms include: the enhance of the stator flux estimation, Fuzzy flux and flux angle compensation controller and implement a VSPI speed controller which can solve the problems associate with the conventional DTC scheme effectively. The performance of the system is investigated and verified experimentally.

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