花了一兩個小時研究了一番powergui的fft。在powergui中,FFT Analysis Tool如圖所示
開發環境:MATLAB R2015a + Window 10 enterpirse

那么如果我想提取出Simulink模型中的數據並且做fft處理,得到自己想要的分析圖像,應該怎么辦呢?
方法一:
其實MATLAB在這個過程中調用了power_fftscope()這個函數。它的函數原型可以在matlab的幫助文檔中找到。函數調用的格式如下。

在command窗口里輸入如下命令即可設定與調用由FFT Analysis Tool產生的波形數據
>> FFTDATA = power_fftscope(Va) %實例化對象FFTDATA,它代表Va的fft結構體數據 FFTDATA = time: [457947x1 double] signals: [1x1 struct] blockName: 'HP/VA' input: 1 signal: 1 startTime: 'last' cycles: 1 fundamental: 60 maxFrequency: 1000 THDmaxFrequency: Inf THDbase: 'fund' mag: [17x1 double] phase: [17x1 double] freq: [17x1 double] THD: 272.5235 samplingTime: 4.3673e-06 samplesPerCycle: 3816 DCcomponent: 14.5702 magFundamental: 48.1973 >> FFTDATA.fundamental = 100 %設定基頻 FFTDATA = time: [457947x1 double] signals: [1x1 struct] blockName: 'HP/VA' input: 1 signal: 1 startTime: 'last' cycles: 1 fundamental: 100 maxFrequency: 1000 THDmaxFrequency: Inf THDbase: 'fund' mag: [17x1 double] phase: [17x1 double] freq: [17x1 double] THD: 272.5235 samplingTime: 4.3673e-06 samplesPerCycle: 3816 DCcomponent: 14.5702 magFundamental: 48.1973 >> FFTDATA.cycles = 200 %設定周期數 FFTDATA = time: [457947x1 double] signals: [1x1 struct] blockName: 'HP/VA' input: 1 signal: 1 startTime: 'last' cycles: 200 fundamental: 100 maxFrequency: 1000 THDmaxFrequency: Inf THDbase: 'fund' mag: [17x1 double] phase: [17x1 double] freq: [17x1 double] THD: 272.5235 samplingTime: 4.3673e-06 samplesPerCycle: 3816 DCcomponent: 14.5702 magFundamental: 48.1973 >> FFTDATA.maxFrequency = 7900 %設定最高頻率 FFTDATA = time: [457947x1 double] signals: [1x1 struct] blockName: 'HP/VA' input: 1 signal: 1 startTime: 'last' cycles: 200 fundamental: 100 maxFrequency: 7900 THDmaxFrequency: Inf THDbase: 'fund' mag: [17x1 double] phase: [17x1 double] freq: [17x1 double] THD: 272.5235 samplingTime: 4.3673e-06 samplesPerCycle: 3816 DCcomponent: 14.5702 magFundamental: 48.1973
>> x = FFTDATA.freq %獲得頻率
x =
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
960
>> y = FFTDATA.mag %獲得幅值
y =
14.5702
48.1973
79.0183
18.0582
9.8706
7.3618
5.3919
4.5902
3.5941
3.4998
3.1022
2.7178
2.7215
2.3526
2.3970
2.6270
2.1154
之后通過簡單的繪圖命令我們就可以繪制出模型的頻譜圖。
方法二:
如果你只是很簡單的想修改由FFT Analysis Tool生成的頻譜分析圖形,不妨試試下面簡單的方法。

在command中新建一個figure
>> figure
打開后選擇工具下的plot edit

然后右鍵粘貼即可。
這樣你就可以通過set()來設定figure的參數,改變圖形的配置。具體要設定gca句柄。
比如
>> set(gca,'yscale','log') %將y軸轉換成對數坐標
對於gca句柄,在[2]中有較為詳盡的命令。
參考:
[1]:http://cn.mathworks.com/help/physmod/sps/powersys/ref/power_fftscope.html;jsessionid=db0b9a8ee73742bf537d1f0a3291?refresh=true#responsive_offcanvas
[2]:http://wenku.baidu.com/link?url=HqIyvz6p9G8IY1Xb01_sXcN_aZjdV8iUk2AuCby1T0WHIKxahcHTPozq2M8UgGqQdjzJElSpfEI2W83EB0gYbRbB3uVGxpJKQjJGJobwR6C
