以DSP晶片實現之無刷直流馬達無感測驅動與速度調整

Abstract

馬達的應用在現今已相當廣泛，舉凡機械手臂、電動車、遙控模型等，而直流無刷馬達因具有高扭力以及不需額外維護的優點較常被使用。要驅動直流無刷馬達，一般傳統的方式都是依賴安裝在馬達內部的霍爾感測器去偵測轉子的位置，並輸出信號給外部的控制器，可是此類的感測器卻會增加馬達體積，也可能受到高溫及高速運轉的影響而損壞。因此，近年來發表的無感測控制方式即可避免使用這些感測器。本論文主要目的是採用估測轉子位置法，從回授的端電壓訊號即時估算感應電動勢，在F2812 DSP控制板上實現直流無刷馬達無感測驅動，馬達的速度也可以藉由調整PWM輸出訊號的duty ratio來改變。此外，程式中亦加入了馬達的啟動程序，克服無感測法不適用於靜止狀態的問題，因此，馬達便可完整的由靜止啟動到達所要求的速度。

Today, the application of the motor is diverse such as robot arms, electric vehicles, radio control (R/C) models, and etc. However, the brushless DC motor, BLDC motor in brief, is utilized popularly because of its high toque and maintenanceless. To drive the BLDC motor, the Hall-effect sensors located inside the motor are traditionally used to detect the rotor position and deliver the information to the controller. However, the sensors will increase the volume of the motor and may cause damage while rotating in high speed and in high heat environment. Thus, a sensorless method is proposed recently to avoid the use of these sensors. This thesis realizes a sensorless drive for the BLDC motor on the powerful F2812 DSP board by implementing the position estimated method, which computes the back-EMFs from the feedback of the terminal voltages of BLDC motor. The speed of the motor is able to be regulated by changing the duty ratio of the input PWM signals. Additionally, an open-loop start-up procedure is adopted to fulfill the rotation from standstill to a fixed speed.