matlab電機學重難點仿真

1、電機學難重點的MATLAB仿真實驗報告鐵磁材料磁化曲線的擬合一、實驗內(nèi)容及目的1.實驗?zāi)康模?）了解磁化曲線的非線性和飽和特性。（2）掌握采用MATLAB進行曲線擬合的方法。2.基本知識在非鐵磁材料中，磁通密度B和磁場強度H之間是線性關(guān)系，其系數(shù)就是空氣的磁導率。而在鐵磁材料中，二者是非線性關(guān)系，稱為磁化曲線。一段典型的磁化曲線如圖1所示。一般的，磁化曲線都有開始階段，線性增長階段，拐彎階段和飽和階段四部分，其中線性增長階段和拐彎階段的交界點就是曲線的膝點。圖1 變壓器磁化曲線由于表征磁化曲線是用磁通密度B和磁場強度H兩維數(shù)組表示的，是不連續(xù)的，而且其變化特征也比較復(fù)雜。當數(shù)據(jù)量很大的時候采用

2、這種數(shù)組形式很不方便，也占用存儲量，最好的處理方式，是采用曲線擬合方法，把磁化曲線表示成顯函數(shù)形式的解析表達式。二、實驗要求及要點描述 （1）采用屏幕圖形方式直觀顯示磁化曲線。 （2）利用編程方法和MATLAB的擬合函數(shù)。 （3）根據(jù)所提供的數(shù)據(jù)，合理選取全部和部分數(shù)據(jù)繪制磁化曲線，并進行比較，不少于4條曲線。（4）繪制每條磁化曲線對應(yīng)的圖和表。（5）在一個圖中顯示全部曲線，并進行區(qū)分。三、基本知識及實驗方法描述 （1）利用編程方法和MATLAB的擬合函數(shù)進行曲線擬合。 （2）由于磁感應(yīng)強度B與電動勢E之間是呈線性關(guān)系的，而磁場強度H和電流I之間也是呈線性關(guān)系的，所以在繪制磁化曲線時可以用E-

3、I曲線來表示B-H曲線，作為磁化曲線。（3）實驗中利用多項式函數(shù)來進行曲線的擬合，在MATLAB中的擬合函數(shù)為p=polyfit(H1,B1,n); poly2str(p,'x'); z=polyval(p,H1);，分別選擇全部數(shù)據(jù)或者部分數(shù)據(jù)進行擬合，先將數(shù)據(jù)選擇好，然后再確定用幾次多項式進行擬合，分別在一個圖中顯示四組數(shù)據(jù)擬合的曲線，更換擬合函數(shù)的多項式次數(shù)在進行實驗，然后分析實驗結(jié)果。四、實驗源程序四張表的數(shù)據(jù)都進行13次擬合>> H1=1.401.431.461.491.521.551.581.611.641.67.1.711.751.791.831.87

4、1.911.951.992.032.07.2.122.172.222.272.322.372.422.482.542.60.2.672.742.812.882.953.023.093.163.243.32.3.403.483.563.643.723.803.893.984.074.16.4.254.354.454.554.654.764.885.005.125.24.5.365.495.625.755.886.026.166.306.456.60.6.756.917.087.267.457.657.868.088.318.55.8.809.069.339.619.9010.210.510.91

5、1.211.6.12.012.513.013.514.014.515.015.616.216.8.17.418.218.919.820.621.622.623.825.026.4.28.029.731.533.736.038.541.344.047.050.0.52.955.959.062.165.369.272.876.680.484.2.88.092.095.6100.0105.0110.0115.0120.0126.0132.0.138.0145.0152.0166.0173.0181.0189.0197.0205.0;>> B1=0.4:0.01:1.89a=polyfit

6、(h1,b1,13)for n=1:151hf1(n)=173*(n-1)/150bf1(n)=a(1)*hf1(n)13+a(2)*hf1(n)12+a(3)*hf1(n)11+a(4)*hf1(n)10+a(5)*hf1(n)9+a(6)*hf1(n)8+a(7)*hf1(n)7+a(8)*hf1(n)6+a(9)*hf1(n)5+a(10)*hf1(n)4+a(11)*hf1(n)3+a(12)*hf1(n)2+a(13)*hf1(n)1+a(14)endplot(hf1,bf1,'k')hold on %選取全部數(shù)據(jù)繪制D21磁化曲線xlabel('H(A/cm

7、)') %標注x，y軸ylabel('B(T)')h2=0.700.720.730.750.760.780.800.810.830.84 0.860.880.890.910.920.940.960.970.991.00 1.021.041.061.071.091.111.131.151.161.18 1.201.221.241.251.271.291.311.331.341.36 1.381.401.421.441.461.481.501.531.551.57 1.601.631.651.681.711.741.771.801.831.87 1.901.941.982.

8、022.062.112.162.222.272.33 2.402.472.542.622.702.792.882.973.063.16 3.263.373.483.593.713.833.974.114.264.41 4.564.734.915.105.305.515.735.966.216.46 6.737.017.317.627.948.278.628.999.379.76 10.1710.6011.0411.4911.9612.4512.9513.4613.9914.54 15.1015.6816.2816.9017.5418.2018.9019.6620.4721.34 22.2623

9、.2624.3825.6227.0028.5330.1331.7533.4035.07 36.8038.6040.4042.2044.0045.8047.7049.6051.5053.40b2=0.4:0.01:1.89a=polyfit(h2,b2,13)for n=1:151hf2(n)=53.4*(n-1)/150bf2(n)=a(1)*hf2(n)13+a(2)*hf2(n)12+a(3)*hf2(n)11+a(4)*hf2(n)10+a(5)*hf2(n)9+a(6)*hf2(n)8+a(7)*hf2(n)7+a(8)*hf2(n)6+a(9)*hf2(n)5+a(10)*hf2(n

10、)4+a(11)*hf2(n)3+a(12)*hf2(n)2+a(13)*hf2(n)1+a(14)endplot(hf2,bf2,'g')hold on %選取全部數(shù)據(jù)繪制D22磁化曲線>> h3=1.381.401.421.441.461.481.51.521.541.56 1.581.601.621.641.661.691.711.741.61.78 1.811.821.831.891.911.941.972.002.032.06 2.102.132.162.202.242.282.322.36242.45 2.502.552.602.652.71.762.8

11、12.872.932.99 3.063.133.196.63.333.413.493.573.653.74 3.833.924.014.114.224.334.444.564.674.8 4.935.075.215.365.525.685.846.006.166.33 6.526.726.947.167.387.627.868.108.368.62 8.909.209.509.8010.110.510.911.3611.712.1 12.613.113.614.214.815.516.317.118.119.1 20.121.222.423.725.026.728.530.432.635.1

12、37.840.743.746.850.053.456.860.464.067.8 72.076.480.885.490.295.0100105110116 122128134140146152158165172180b3=0.4:0.01:1.89len3=length(h3)hmax3=h3(len3)a=polyfit(h3,b3,13)for n=1:151hf3(n)=180*(n-1)/150bf3(n)=a(1)*hf3(n)13+a(2)*hf3(n)12+a(3)*hf3(n)11+a(4)*hf3(n)10+a(5)*hf3(n)9+a(6)*hf3(n)8+a(7)*hf3

13、(n)7+a(8)*hf3(n)6+a(9)*hf3(n)5+a(10)*hf3(n)4+a(11)*hf3(n)3+a(12)*hf3(n)2+a(13)*hf3(n)1+a(14)endplot(hf3,bf3,'m')hold on %選取全部數(shù)據(jù)繪制D23磁化曲線h4=1.371.381.41.421.441.461.481.501.521.54 1.561.581.61.621.641.661.681.701.721.75 1.771.791.811.841.871.891.921.941.972.00 2.032.062.092.122.162.202.232.27

14、2.312.35 2.392.432.482.522.572.622.672.732.792.85 2.912.973.033.13.173.243.313.393.473.55 3.633.713.793.883.974.064.164.264.374.48 4.604.724.865.005.145.295.445.605.765.92 6.106.286.466.656.857.57.257.467.687.90 5.148.408.388.969.269.589.8610.210.611.0 11.411.812.612.813.313.814.415.015.716.4 17.218

15、.018.919.920.922.123.525.026.828.6 30.733.035.638.241.144.047.050.053.557.5 61.566.070.57579.784.589.594.7100105 110116122128134141148155162170b4=0.4:0.01:1.89a=polyfit(h4,b4,13)for n=1:151hf4(n)=170*(n-1)/150bf4(n)=a(1)*hf4(n)13+a(2)*hf4(n)12+a(3)*hf4(n)11+a(4)*hf4(n)10+a(5)*hf4(n)9+a(6)*hf4(n)8+a(

16、7)*hf4(n)7+a(8)*hf4(n)6+a(9)*hf4(n)5+a(10)*hf4(n)4+a(11)*hf4(n)3+a(12)*hf4(n)2+a(13)*hf4(n)1+a(14)endplot(hf4,bf4,'b') %選取全部數(shù)據(jù)繪制D24磁化曲線 五、實驗結(jié)果（1）硅鋼片D21磁化曲線圖和表A/cm00.010.020.030.040.050.060.070.080.090.41.41.431.461.491.521.551.581.611.641.670.51.711.751.791.831.871.911.951.992.032.070.62.122

17、.172.222.272.322.372.422.482.542.600.72.672.742.812.882.953.023.093.163.243.320.83.403.483.563.643.723.803.893.984.074.160.94.254.354.454.554.654.764.885.005.125.241.05.365.495.625.755.886.026.166.306.456.601.16.756.917.087.267.457.657.868.088.318.551.28.809.069.339.619.9010.210.510.911.211.61.312.0

18、12.513.013.514.014.515.015.616.216.81.417.418.218.919.820.621.622.623.825.026.41.528.029.731.533.736.038.541.344.047.050.01.652.955.959.062.165.369.272.876.680.484.21.788.092.095.61001051101151201261321.8138145152195166173181189197205（2）硅鋼片D22磁化曲線圖和表 00.010.020.030.040.050.060.070.080.090.40.700.720

19、.730.750.760.780.800.810.830.840.50.860.880.890.910.920.940.960.970.991.000.61.021.041.061.071.091.111.131.151.161.180.71.201.221.241.251.271.291.311.331.341.360.81.381.401.421.441.461.481.501.531.551.570.91.601.631.651.681.711.741.771.801.831.871.01.901.941.982.022.062.112.162.222.272.331.12.402.47

20、2.542.622.702.792.882.973.063.161.23.263.373.483.593.713.833.974.114.264.411.34.564.734.915.105.305.515.735.966.216.461.46.737.017.317.627.948.278.628.999.379.761.510.1710.6011.0411.4911.9612.4512.9513.4613.9914.541.615.1015.6816.2816.9017.5418.2018.9019.6620.4721.341.722.2623.2624.3825.6227.0028.53

21、30.1331.7533.4035.071.836.8038.6040.4042.2044.0045.8047.7049.6051.5053.40（3）硅鋼片D23磁化曲線圖和表00.010.020.030.040.050.060.070.080.090.41.381.401.421.441.461.481.51.521.541.560.51.581.601.621.641.661.691.711.741.61.780.61.811.821.831.891.911.941.972.002.032.060.72.102.132.162.202.242.282.322.36242.450.82.5

22、02.552.602.652.71.762.812.872.932.990.93.063.133.196.63.333.413.493.573.653.741.03.833.924.014.114.224.334.444.564.674.81.14.935.075.215.365.525.685.846.006.166.331.26.526.726.947.167.387.627.868.108.368.621.38.909.209.509.8010.110.510.911.3611.712.11.412.613.113.614.214.815.516.317.118.119.11.520.1

23、21.222.423.725.026.728.530.432.635.11.637.840.743.746.850.053.456.860.464.067.81.772.076.480.885.490.295.01001051101161.8122128134140146152158165172180（4）硅鋼片D24磁化曲線圖和表A/cm00.010.020.030.040.050.060.070.080.090.41.371.381.41.421.441.461.481.501.521.540.51.561.581.61.621.641.661.681.701.721.750.61.771

24、.791.811.841.871.891.921.941.972.000.72.032.062.092.122.162.202.232.272.312.350.82.392.432.482.522.572.622.672.732.792.850.92.912.973.033.13.173.243.313.393.473.551.03.633.713.793.883.974.064.164.264.374.481.14.604.724.865.005.145.295.445.605.765.921.26.106.286.466.656.857.57.257.467.687.901.35.148.

25、408.388.969.269.589.8610.210.611.01.411.411.812.612.813.313.814.415.015.716.41.517.218.018.919.920.922.123.525.026.828.61.630.733.035.638.241.144.047.050.053.557.51.761.566.070.57579.784.589.594.71001051.8110116122128134141148155162170（5）四條磁化曲線在一個表中 3、實驗結(jié)果的分析從擬合的磁化曲線我們可以看出，當磁場強度比較小時，磁通密度與磁場強度基本呈線性關(guān)系

26、，也稱為起始階段和線性增長階段，隨著H的逐漸增大，磁通密度趨向于飽和，當H增加到很大時，磁通密度基本保持不變，即進入了飽和階段，可見，實驗結(jié)果與理論分析基本一致。四種硅鋼片由于工藝不同，對應(yīng)的磁化曲線也有所不同，實際中可以根據(jù)需要進行選擇。單相變壓器的電壓變化率曲線及效率曲線一、實驗內(nèi)容及目的1.了解變壓器電壓變化率的變化規(guī)律；2.了解負載性質(zhì)對電壓變化率特性的影響；3.了解變壓器效率曲線的變化規(guī)律；4.了解負載特性對效率曲線的影響。二、實驗要求及要點描述1.采用屏幕圖形方式直觀顯示；2.畫出對應(yīng)阻性、感性、容性三種負載性質(zhì)的特性曲線，且要通過額定點；3.畫出對應(yīng)不同負載功率因數(shù)的效率曲線，且

27、通過額定點；4.給出特征性的結(jié)論。三、基本知識變壓器一次接額定電壓，二次側(cè)空載時的電壓就是額定電壓。當二次側(cè)接入負載后，即使一次側(cè)電壓不變，二次側(cè)的電壓也不再是額定值，變化后的電壓大小與負載電流、負載性質(zhì)和短路阻抗參數(shù)有關(guān)。表征該變化的物理量就是電壓變化率，根據(jù)電機學理論，電壓變化率為：1.對于阻性負載，有；2.對于感性負載，有，而且數(shù)值比阻性的大，；3.對于容性負載，則可能出現(xiàn)；在所有種類電機中，變壓器效率最高，而且高效工作區(qū)間很寬，一般效率在95%-99%之間。變壓器的效率是指輸出功率和輸入功率之間的比值：根據(jù)上式，就可以求出對應(yīng)不同的負載功率因數(shù)，當負載電流的標幺值在0,0.12區(qū)間內(nèi)變

28、化時，變壓器的效率曲線。四、實驗源程序1.電壓變化率曲線：clear;Rk=0.0093;Xk=0.04821;cos=0.85;sin=0.52678;I1=0:0.001:15.15;I2=0:0.001:1;dUz=I1*(Rk*cos+Xk*sin);dUn=I1*(Rk*1+Xk*0);dUq=I1*(Rk*cos-Xk*sin);U2z=1-dUz;U2n=1-dUn;U2q=1-dUq;plot(I1,U2z,'r',I1,U2n,'-.g',I1,U2q,'-b',I1,1,'k:');axis(0 1.2 0.5 1.2);title('變壓器的外特性');ylabel('額定U_2 (%)');xlabel('額定I_2 (%)');text(0.81