直流無刷馬達無感測驅動及可調變數位濾波器之研究

Research on Sensorless Drive and Variable Digital Filter Design for Brushless DC Motor

周育俊(Yu-Chun Chou)

指導教授 ： 范憶華

中原大學/工學院/機械工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500687

摘要

摘要

無刷直流馬達具有高效率、高功率密度與高轉速控制範圍等優點，在霍爾元件易受溫度影響的情況下，結合無感測控制技術，更可以低成本方式發揮無刷直流馬達的效能。
在考量到這些問題下，以不需轉子位置訊號量測之無轉軸偵測元件驅動器成為一極具有發展潛力之驅動技術。而無感測器驅動的技術中，又以反電動勢估測的端電壓量測法最為常見。但其缺點為馬達在低轉速下會因為反電動勢太小而使馬達換相訊號不準確的情況產生而降低效率，所以傳統上只限用於馬達中、高轉速的情形。而傳統無感測器馬達驅動都需要外加硬體的輔助，硬體除了成本的增加外，也有維護上的困擾。
因此本論文主要的目的是利用一數位濾波器取代傳統類比濾波器的功能，並解決低轉速下電壓訊號過小與高轉速下調整其相位落後的補償以完成轉速估測及換相訊號的提供，達到低轉速閉迴路系統的速度控制。
論文中利用Labview軟體之AD/DA轉換透過 I/O卡將馬達三相電壓類比訊號轉換為數位訊號，再利用Matlab軟體，經由快速傅立葉轉換(FFT)來比較數位濾波器前後訊號。最後以TI-F240 DSP為韌體，作為軟體實現之介面。並利用所設計之硬體與軟體，達到以DSP實現無感測驅動之目標。由時域與及分析過後之頻域訊號結果比較，顯示利用本文提出之方法，可以有效減少馬達低轉速下零交越點誤判，達到2Hz左右之無感測轉速控制。

關鍵字

快速傅立葉轉換 ； 數位濾波器 ； 無感測器驅動 ； 直流無刷馬達

並列摘要

Abstract

The Brushless DC (BLDC) motor is provided with some advantages, such as high efficiency, high power density and high rotational speed range. But the position sensor such as the encoder or the Hall sensor tends to be affected under the condition of high temperature or other rigorous environments, thus the drivers that have not position sensor be the potential driver techniques. And we can pay low cost and bring the efficiency of BLDC by this way.
Among the technique of sensorless drive, the terminal voltage sensing is the most common one. However, its disadvantage is that the back emf is small under low rotating speed. The communication of the phase of motor is not exact because back emf too small as the phase change signal will be interfered by the noise. As a result, it is restricted to use at not low rotational speed. And the traditional sensorless of the motor driver needs extra assistance by hardware; it will increase the cost of manufacture and maintenance.
The paper proposes a new way to solve the erroneous judgment of the change phase signal in the lower rotating speed for the end voltage detection method with BLDC motor sensorless control. We try to use a digital filter with changeable gain to replace the traditional analog filter. The purpose is to solve the back emf voltage too slow in low speed for the end voltage detection method. Furthermore the phase lag in FIR filter is linear, that is, we can compensate the phase lag when rotating in high-speed range to the phase commutation signal and to finish the speed control in close loop system.
We catch the real signal of motor to a digital signal by the I/O card and analysis the signal by the software of Matlab. From the time signal and the frequence signal by the Fast Fourier Transform (FFT), this method can reduce the erroneous judgment in the lower rotating speed and we can drive the motor by sensorless control method to 2Hz.

並列關鍵字

digital filter ； FFT ； BLDC ； sensorless

參考文獻

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