無位置感測器直流無刷馬達新型換相技術之研究

Abstract

直流無刷馬達因為具有高效率、高可靠度等優點，因此近年來被廣泛的應用在各種家庭與工業場合。一般控制直流無刷馬達需要霍爾元件(Hall sensors)來偵測轉子位置和轉速，但在較為極端的操作環境下如高溫、體積狹小或是節省成本考量的情況下，並不適用霍爾感測器。因此直流無刷馬達無感測器的控制方法變成為本文主要考量。

本論文擬以干擾觀測器(Disturbance observer, DOB)架構為基礎，提出了一種對直流無刷馬達反電動勢零交越點的偵測方式，來取代霍爾元件並達成直流無刷馬達無感測器控制，此法藉由適當設計Q-filter來準確的估測反電動勢零交越點並用以判斷馬達正確的換相時機，接著為了確實降低馬達轉矩漣波(torque ripple)，我們擬引入PWM切換方式(PWM-ON-PWM)來實現無感測器下也能有效消除馬達漣波。

此外，本文也提出了一種能夠放大反電動勢的偵測方式，並且利用同步取樣原理來降低共模雜訊，利用這種方式，不需要使用到電流資訊，所以可以降低硬體需求並使得零交越點的量測更為準確。

Brushless DC motors (BLDCM) were extensively used in recent years due to its high efficiency and high reliability. In general, controlling the BLDCM use the Hall sensors to detect the corresponding position and velocity of rotor; however, in some extremely industrial applications, such as high temperature surrounding, small size, and economical limitation, it is not suitable to apply Hall sensors. For these reasons, many papers pay attention to the control schemes of sensorless BLDCM. This research proposed a new back-electromotive force (back-emf) detection scheme based on disturbance observer. This obverse-based structure with a designed proper Q-filter is used to estimate the zero crossing point of back-emf to obtain a sensorless BLDCM without the Hall sensors. Finally, the correct commutating signal can be achieved. Furthermore, in order to reduce the torque ripple of BLDCM from the current conduction in the nonexcited phase, we introduced a pulse width modulation (PWM) technique (PWM-ON-PWM) to achieve a better alleviating torque ripple performance on sensorless mode of BLDCM.

On the other hand, another new back-electromotive force (back-emf) detection scheme, which can not only amplify the back-electromotive force (back-emf) but also reduce the common mode noise with the application of the synchronous sampling detection method, is also proposed in this research. Because the current information is not needed by using the proposed scheme, the hardware requirement can be easily achieved and the precision of the back-emf detection can be promoted.