新型超音波馬達和一般電磁馬達相較有顯著的優點，如體積小、低噪音運行、可忽略磁場干擾、低轉速時高轉矩、高保持轉矩、結構簡單，加工容易…等等。因此在一些需要安靜的場合，如辦公室、醫院，或是容易受到電磁干擾的地方，如核磁共振設備，以及精密定位設備、照相機自動對焦系統、機械手臂，甚至是汽車工業、航太工業…等等，使用超音波馬達有越來越普遍的趨勢，而且超音波馬達的設計相當多樣化，因此超音波馬達在未來有著相當廣泛的應用前景。
超音波馬達的特性複雜且高度非線性，其馬達參數易受溫度上升、驅動頻率、驅動電壓及兩相電壓之相位差等變數所影響。在傳統超音波馬達驅動器設計，通常只能控制兩相電壓之切換頻率大小，但相位差固定在90度，且輸出電壓振幅容易受到品質因數的影響，造成兩相電壓的不平衡，因此不能有效獲得良好的控制基礎。故本論文提出一種新穎超音波馬達驅動電路設計，能夠產生可調整頻率與可變相位差之兩相相同振幅之弦波電壓，進而對超音波馬達進行精確且快速的速度響應控制。另外此超音波馬達驅動電路，設計結構簡單、成本低廉、易於實現與高實用性。
最後，藉著數位訊號處理器高精確度、不易受溫度變化與雜訊干擾之特性，以實現全數位元化之超音波馬達控制系統。由實驗結果可以看出本論文所提出的驅動器，可獲得良好的控制性能及精確的速度響應，並且驗證了本新穎驅動器在超音波馬達應用上，有著相當良好的效能與高實用性。

The newly traveling-wave ultrasonic motor (TWUSM) compared with conventional electromagnetic motors has many excellent performances, such as compactness in size, high torque at low speed, high holding torque, no electromagnetic interferences and so on. Therefore, the TWUSM has been used in many practical areas such as industrial, medical, robotic, and automotive applications.
The control characteristic of the TWUSM is complicated and highly nonlinear. Moreover, the motor parameters are time-varying owing to increases in temperature and changes in motor drive operating conditions, such as driving frequency, voltage amplitude and phase difference of two-phase voltages. The conventional driving circuits are regulated the frequency of the sinusoidal voltage waveforms, but the phase difference of the two-phase voltages is fixed at 90 degrees. In addition, the output voltage gain is seriously varied for the variation of the quality factor. Thus, the two-phase sinusoid output voltages will be unbalanced that affects the performance of the ultrasonic motors with the conventional driving circuits. For the reason, this thesis presents a novel driver system for the TWUSM, which incorporates frequency control, phase-difference modulation, and provides two-phase balanced voltage to improve the drawback of conventional driving circuit. The goals for novel driving circuit design are to satisfy these requirements, as well as high power efficiency and reduce the system hardware size and cost. With the novel driving circuit of TWUSM, the system will have quick and precise speed response.
From the detailed experimental results of this study are showed a superior performance for the TWUSM. Furthermore, the results are provided to demonstrate the effectiveness of the proposed driving circuit.

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