Project - Speed Control of a Direct Current (DC) motor

conditons considerd for DC motor

J = 0.01; % moment of inertia of motor(kg-m^2)

B = 0.1; % motor viscous friction constant (N-m-s)

Km = 0.01; % back EMF constant (v/rad/s)

Kt = 0.01; % motor torque constant in (N-m/amp)

Ra = 1.0; % resistance of armature circuit(ohm)

La = 0.5; % inductance of armature circuit(henrry)

a1 = J*La; % charecteristic equation coefficients

b1 = J*Ra+B*La;

c1 = B*Ra+Kt*Km;

n = [a1 b1 c1];

P = roots(n); % poles

a = [-B/J Kt/J; -Km/La -Ra/La];

b = [0; 1/La];

K = place(a,b,P);

%Kp = 1.0e-14*0.1476;

%Kd = 1.0e-14*0.0222;

at first the gain was set as kp and kd as poles and ki =0 the resulting speed dosent matches the requirements (settling time more than 2 sec was observed). after that the ki was increased then the overshoot exeeded to more than 5%.

therfore the kp kd and ki it taken as zero and then selected accordingly.

At

Kp = 20;

Kd = 20;

ki = .001;

the speed satisfies the requirement of oveshoot less than 5%, settling time lessthan 2sec and steady state error lessthan 1%.

at the givan 12v input the dc motor produces a speed of approx 8rad/sec. ie 76rpm.