汽車車輪馬達雛形製作及最佳驅動控制的實現

Abstract

本文針對本實驗室設計之直流無刷車輪馬達作最佳驅動方式之研究。首先，利用以能量法推導之力矩方程式討論電流與反電動勢之關係，得到當電流波形等於反電動勢波形時，能得到最大力矩，則最佳電流波形即反電動勢波形。再來利用有限元素分析軟體，建立三維模型，模擬馬達之反電動勢波形，並將得到的反電動勢波形解析為不同階數之弦波，然後加以比較馬達的力矩輸出與力矩漣波，最後得到一最適合之電流波形。並將馬達雛形製造完成，最後利用實驗的方式測試最佳波形之效能，以及以其他波形驅動之效能比較。 實驗結果中馬達反電動勢波形與模擬結果相當接近，可間接證明馬達力矩亦與模擬結果接近，但實驗結果發現馬達受到換相訊號偏移的影響，因此力矩表現約減少了20%，建議使用編碼器以改善訊號偏移的問題。

The thesis proposes a novel design and optimal driving current wave for a brushless DC wheel-motor. First, we obtain the realization of current and back EMF waveform from the torque equation of motor constructed by energy method. The wheel motor has a maximum torque as the current and the back EMF waveform are proportional, i.e., the optimal current waveform follows the back EMF waveform. Second, we establish a 3-D model by the finite element analysis software, and obtain the results of simulation of the back EMF waveform. In the 3-D finite element analysis model, we decompose the back EMF waveform into different order of partial sums to analyze the corresponding torque and torque ripple. Then, the best current waveform is determined. Finally, we fabricate a prototype for the wheel motor and drive it with square, sinusoidal, and optimal current waveforms to test the wheel-motor’s performance. It is shown by experiment that the back EMF waveform is similar to that obtained by finite element analysis, which reveals that the wheel motor must produce satisfactory torque. However, the torque from experiments reduces about 20% because of the malfunction of encoder signals. More improvement of the wheel motor is to expected before the implementation on a passenger car.