Speed control of DC Motor.

Introduction:

DC motor is a electrical machine. Who converts the electrical energy to mechanical energy. There are four types of DC motor separately excited, shunt, series and compound.    

Problem Statement:

  In armature-controlled DC motors, the applied voltage Va controls the angular velocity w of the shaft.

This demo shows two techniques for reducing the sensitivity of w to load variations (changes in the

torque opposed by the motor load).

A simplified model of the DC motor is shown above. The torque Td models load disturbances. You must

Minimize the speed variations induced by such disturbances.

Math Lab Coad:

R = 2.0;

L = 0.5;

Km = 0.1; Kb = 0.1;

Kf = 0.2;

J =0.02;

h1 = tf(Km,[L R]);

h2 = tf(1,[J Kf]);

dcm = ss(h2) * [h1 , 1];

dcm = stepplot(dcm(1));

feedback(dcm,Kb,1,1);0.02;

stepplot(dcm(1));

Working procedure:

1. Firstly open the MATLAB Software.

2. Then mouse click the File menu to New M-file.

3. Then we write program in editor file and editor file program save in the MATLAB Software.

4. Then run the program and we can get graphical figure Settling time and Rising time.

5. At last we explain this work in our teacher.

Result and simulation:

Right-click on the plot and select "Characteristics: Settling Time and Rising Time " to display the settling time and rising time.

Then we change the value of R and L. We can get different value of Settling Time and Rising Time.

No	R	L	Settling time	Rising time
01	2.0	0.5	1.11	0.617
02	1.0	0.1	0.583	0.336
03	1.2	0.3	1.11	0.617
04	1.4	0.5	1.51	0.836
05	1.6	0.7	1.83	1
06	1.8	0.9	2.07	1.14
07	2.0	1.0	2.07	1.14
08	2.3	0.2	0.547	0.314
09	2.5	0.4	0.777	0.442
10	1.0	1.0	2.22	4.02

Conclusion:

We do this experiment to know that, how we can control the motor speed. When the motor settling time and rising time is zero or approximately zero, then our result will successful. But  we can not fiend this accurate value of zero.