感應馬達在本身結構特性上有許多的優點，如架構堅固、亦於維護、價格便宜等優點，所以在工業應用的場合中，感應馬達是扮演了相當重要的角色。近幾年來更由於向量控制技術日漸成熟，特別是直接轉矩向量控制的發展，使得感應馬達能擁有如直流馬達一般優異的操控性能，所以可以預見，結合向量控制技術的感應馬達驅動器將會漸漸地成為市場上的主流。 然而在高性能的感應馬達控制中，為了使整個轉速操作範圍都有快速的轉速轉矩響應，通常都需要加裝速度感測器作回授信號的量測，但是在驅動系統中安裝感測器不僅增加系統的成本、維修上的難度、也降低了驅動器的強健性及系統的可靠度。 因此在本論文中將設計無感測器系統，以避免感測器所造成上述的問題。設計的方式是以端電壓及線電流的回授，估算出磁通的同步旋轉速度，並經由滑差轉速的估算與補償後,得到估測的馬達轉速，完成無感測器閉迴路的速度控制。並且針對傳統無感測器系統在加載操作情況下，轉矩無法有效輸出的缺點，提出以模糊滑差轉速估算器來取代傳統滑差轉速估測式，有效的提昇加載時系統的轉矩響應，使得系統在無需感測器的情況下，仍然具有良好的轉速及轉矩輸出，增加系統的可行性與實用性。 由於本論文所設計的無感測器系統是以直接轉矩控制為基礎，所以其效能是直接的受到磁通估測準確性所影響。因此，本論文將針對低轉速時磁通估測所造成的問題，應用新型磁通估測補償器來估算磁通，有效的改善低轉速時磁通估算的正確性，同時也提高了無感測器系統在低轉速時的性能。 論文中所提出的方法，經由模擬驗證其可行性後，再以硬體實際測試結果，來驗證其高度的效能，藉以佐證出新型無感測器之直接轉矩控制感應馬達驅動系統於實用上的價值。 Induction motors have been widely used in industry applications. According to its mechanical structure identities, the induction motor has a lot of advantages such as stable structure, low price, simplicity of maintenance and so on. Recently, vector control technique has been well developed, especially the direct torque control (DTC) algorithm. It has been shown that vector controlled induction motors have the properties as DC motors. Most high performance induction motor driver systems used the speed sensor to detect the feedback signal (rotor speed). However, using encoder would decrease the competitive advantage of induction motor and reduce the reliability of the system. To avoid using speed sensor, this thesis, firstly estimates the synchronous speed and slip speed from motor terminal voltages and currents. The difference of these two signals equals rotor speed, which is fed back to the speed control loop in the sensorless DTC speed control system. Experiment results show that this kind of sensorless direct torque control could not drive the system when loading. To solve this problem, a fuzzy slip-speed estimator is proposed. It is shown that the new estimator can estimate motor speed correctly and induce the torque effectively even in loading condition. Moreover, the accuracy of stator flux is critical to sensorless DTC system. To accurately estimate stator flux in low speed range, a new method is used to estimate stator flux, which effectively improves the performance of sensorless system at low speed range. The performance of the sensoless control system is investigated and verified experimentally.
