適應性濾波器在直流無刷馬達無感測驅動應用研究

Research on Adaptive Digital Filter Application in Sensorless Drive for Brushless DC Motor

柯文隆(wen-long ke)

指導教授 ： 范憶華

中原大學/工學院/機械工程學系/碩士(2006年)

https://doi.org/10.6840/CYCU.2006.00389

摘要

本研究討論直流無刷馬達無感測驅動時，使用適應性濾波器偵測反電動勢波形通過零交越點的應用。
當我們以數位方式量測馬達反電動勢做為轉子位置偵測時，除受外在環境干擾及電路雜訊影響外，類比數位轉換的不準確性也會影響到零交越點偵測的準確度，這種情況在低轉速低電壓時特別明顯。此時雜訊位準往往大過反電動勢位準，使得零交越點位置偵測產生誤判的情況特別明顯，造成換相訊號不正確。由於上述原因，本研究嘗試設計一適應性數位濾波器，隨著馬達轉速變化而使濾波器帶通區間頻率隨之改變，以便在馬達轉速頻率的區間有著最小的雜訊，減少零交越點誤判情況發生，提高運轉效率，使得馬達具有較寬的轉速控制範圍。
適應性數位濾波器主要包括兩個部分：數位濾波器構成及數位濾波器加權參數的適應性演算法設計。本研究採用之數位濾波器是由有限脈衝響應濾波器構成；適應性演算法以結構簡單的最小平方法做為適應性演算法基本架構，來調整有限脈衝響應濾波器之係數，以達到自我調適的功能，此外為了提高運算效率，將其正規化增加其收斂性。另外由於小波理論是近年來最常被用於訊號處理的方法，因此本研究加入小波理論的應用，比較二者結果之間的差異，說明適應性數位濾波器的效能。
實驗結果顯示在低轉速時適應性數位濾波器獲得之換相訊號能有效的濾除雜訊，改善零交越點的誤判，且相位誤差都在可接受範圍30度相位之內。適應性數位濾波雖不及小波理論有效率的濾除雜訊，但是零交越點的判斷也有不錯的效果，二者相差不大。

關鍵字

無感測驅動 ； 反電動勢偵測 ； 適應性數位濾波器

並列摘要

This research discusses the adaptive digital filter applied to the zero across points detecting for the sensorless control in the brushless direct current motor by the counter electromotive force terminal voltage quantity measurement method.
When we detect the motor counter electromotive force to decide the rotor position, the external environment disturbance and the hardware uncertainties such as electric circuit noise and A/D-D/A transformed inaccuracy can affect the accuracy of the change phase signal. The situation is especially obvious when the motor is operating in the low rotational speed. In such a situation, the low voltages of the motor counter electromotive force combined with the oversized noises causes the zero across points detecting signals be disturbed and bring the erroneous judgments. Therefore, this research attempts to design an adaptive digital filter making the filter band-pass frequency change along with the motor rotational speed to reduce the effects of noise, and then the motor can be driven in a wider speed control scope with a better operating efficiency.
The adaptive digital filter mainly includes two parts: one is the digital filter structure; the other is the algorithm of the adjustment of the weighting parameters. The digital filter is constituted by the FIR filter. The adaptive deductive method is based on the least-mean-square method. We adjust the coefficients of the FIR filter by the calculated result of the least-mean-square method. Furthermore, we normalized the signals to increases the astringency of LMS method. Besides, the wavelet theory was the common used signal process method in the past few years; this research used the wavelet theory to analyze the counter electromotive force signals. The both results are compared to explain the potency of the digital filter.
The experimental results showed that the adaptive digital filter can filter the noise and disturbance and the phase lag can be effective improvement in the low rotational speed. The filter reduces the error decisions of the zero across points detecting signals; also the phase error was in an acceptable range of scope 30 degrees. The adaptive digital filter is not as good as the wavelet theory for the noise rejection. But both of difference was not clearly.

並列關鍵字

the adaptive digital filter ； the counter electromotive force detects ； sensorless control

參考文獻

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