為了得到良好的控制性能以及快速的暫態響應，轉矩漣波的改善已被廣泛的需求在許多的應用上。因此如何將速度變動、震動以及雜訊等因素所造成的影響最小化，是目前改善直流無刷馬達轉矩漣波的主要研究方向。最常被應用來研究消除轉矩漣波的方法為傅立葉分析、有限元素法以及最小平方等。而這些方法因為分析上較為複雜，因此在計算上比較容易發生計算錯誤，或是浪費太多時間在分析和計算上。因此，本論文提出一個新方法，利用基因演算法的原理來改善直流無刷馬達的轉矩漣波。

　　此方法是在反電動勢波形已知的條件下，利用基因演算法來搜尋最合適的三相定子電流的傅立葉係數。並將所搜尋到的傅立葉係數重新組成三相的電流波形，而此電流波形即是最適合已知的反電動勢波形，因為用此電流來驅動直流無刷馬達，只要此電流被成功地實現，所得到的轉矩漣波將會最小。而此方法的優點為無論反電動勢波形為弦波、梯形波或者兩者皆不是，只要在反電動勢已知的條件下，即可利用此方法來找出最理想的三相電流波形，不需經過複雜的分析或是計算，因此這方法具有良好的便利性。本論文分別利用Matlab-Simulink和TMS320F2812 DSP實驗版來模擬跟實驗所提出方法的效能跟實用性。其中，將所得到的三相理想電流波形和三相的反電動勢波形皆是以建表的方式來呈現，並根據轉子角度位置和速度來決定適當的輸出波形。由所得到的模擬跟實驗結果可知，本論文所提出的方法可以有效的改善直流無刷馬達的轉矩漣波。在反電動勢波形已知的條件下，只要利用所提出的方法即可成功的找到理想的三相電流波形，而且用此電流來驅動馬達所得到的轉矩漣波即為最小。

　Torque ripple reduction of the brushless DC motor has been the main issue of the servo driving systems in which the speed fluctuation, vibration, and acoustic noise should be minimized. Most methods for suppressing the torque ripples usually require Fourier series analysis, finite element analysis or least-mean-square minimization etc. These methods might lead to error during the complex Fourier series analysis and cost much time on calculation. In this thesis, a new method to improve the torque ripple based on the Genetic Algorithm is presented.

　The proposed method which is depended on Genetic Algorithm is to search the Fourier coefficients of three-phase stator currents for the given back-EMF waveforms which can be the pure sinusoidal and the pure trapezoidal shape or not. Then these Fourier coefficients can be used to recompose the three-phase optimum current commands for a three-phase balanced brushless DC motor driving. Therefore, the torque ripple must be expected to improve through this way, if the stator currents are perfectly achieved. The validity and practical applications of the proposed method are verified from the simulations and experimental results by using Matlab-Simulink tool and TMS320F2812 DSP respectively. In the simulation and experiment structure, the three-phase optimum current commands and the measured three-phase back-EMFs are set up as the tables. And they are obtained according to the rotor angle and speed information from the encoder. From the simulation and experiment results can prove that the proposed method provides a simple and efficient way to obtain three-phase optimum stator currents for the given back-EMF waveforms and the minimum torque ripple will be acquired too.

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