由於近來電力電子技術的進步，針對數十萬瓦以上的額定設備，高功率半導體開關元件切換頻率可以達到數千赫茲以上，進而帶動電壓源變頻器在高速馬達驅動領域上的應用與發展。
在電壓源變頻器與馬達驅動系統中，常使用到脈波寬度調變(Pulse Width Modulation, PWM)技術。針對高速馬達驅動器的應用，脈波寬度調變技術會受到高功率半導體開關之切換頻率與變頻器之直流電壓的限制。如何在此兩種限制下得到高品質的理想輸出電壓波形與電壓增益，是高速馬達驅動系統的重點發展項目。

在本論文中提出一綜合性的脈波寬度調變策略，在線性調變區(linear-modulation region)中，本論文採用一般常見的弦波式脈寬調變(Sinusoidal Pulse Width Modulation, SPWM) 策略以進行開關切換；當系統進入過度調變區(over modulation region)時，由於傳統弦波式脈波寬度調變之輸出電壓有限，此時改採用不連續脈波寬度調變(Discontinuous Pulse Width Modulation, DPWM)策略切換，使系統能夠得到更高的電壓增益；利用此一綜合性的調變策略，配合同步框電流控制器操作於同步脈寬調變模式，可避免因有限的切換頻率所造成的次諧波現象產生。

研究內容包括：緒論、文獻回顧、控制器理論與操作原理、模擬結果分析與討論、實驗結果分析與討論及結論等六個章節。本論文將針對相關文獻作一回顧，並探討系統在不同調變區的特性差異。本研究將以模擬與實驗結果驗證所提切換策略之效能。

With the advances of power electronics technologies, the switching frequency of power semiconductors has reached several kilo-Hz for hundreds of kilo-watt ratings. Such progress leads to the development of voltage source inverters and high speed drives technologies.
Pulse Width Modulation (PWM) techniques have been widely used in inverters and motor drives systems. For high speed drives applications, the PWM operation often face the limit of the switching frequency of the power semiconductors and the limit of the inverter DC bus voltage. Therefore, how to obtain a high quality voltage output waveform with sufficient magnitude under the constraints of switching frequency and DC bus voltage becomes an important issue for high-speed motor drives.

In this thesis, a combination of PWM techniques will be presented. The proposed scheme uses conventional sinusoidal PWM (SPWM) in the linear modulation region, and switches to the Discontinuous PWM (DPWM) in the over modulation region to extract wider linear modulation range. Both modes of PWM operate under the principle of synchronous PWM to avoid undesirable sub-harmonics under limited switching frequency. A Proportional-Integral current regulator under the synchronous reference frame will also be included in this system to evaluate the effectiveness of the proposed PWM schemes.

This thesis will provide a survey of related literature, and discuss the distinct phenomena in different modulation regions. Simulation results and experimental results will be provided to validate the performance of the proposed strategies.

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