Induction Motor Efficiency Characteristics

Aim:

1. Make a MATLAB program which plots contour of given motor speed, torque and efficiency values. Attach the code as a .m file attach a screenshot of all the plots

Solution:

A Matlab program is written to plot the effifciency contour of an Induction Motor:

Description of Program:

• The fixed parameters of the motor are mentioned.
• User input parameters are mentioned.
• Torque and motor speed are calculated with varying values of slip from 1 to 0 inside a for loop.
• Meshgrid is done between Motor speed and torque.
• The losses,input and output power and the efficiency is calculated.
• Countour is plotted.

Program:

% Induction motor efficiency contour

clear all 
close all
clc

% Motor Characteristics:

R1 = 0.641;
R2 = 0.332;
X1 = 1.106;
X2 = 0.464;
V = input('Enter the Voltage : ');
K_c = 0.2;
K_i = 0.008;
K_w = 0.00001;
p = input('Enter the no.of poles : ');
slip = 1:-.01:0;
f = input('Enter the frequency : ');
w_s = 120*(f/p)*0.1047;

for i = 1:length(slip)
    w_m(i) = w_s*(1-slip(i));
    T(i) = (3/w_s)*((V^2*(R2/slip(i)))/((R1+(R2/slip(i))^2+(X1+X2)^2)));
end

% Meshgrid
   [W_m,t] = meshgrid(w_m,T);

% Calculation losses and Efficiency:
    Cl = K_c.*t.^2;
    Il = K_i.*W_m;
    Wl = K_w.*W_m.^2;
    Const_l = 0.2.*W_m;
    P_out = (2*3.14*(W_m/0.1047).*t)/60;
    P_in = P_out+Cl+Il+Wl+Const_l;
    eff = P_out./P_in;
    
% Plotting Contour:
contourf(W_m,t,eff)
xlabel('Motor Speed (rad/sec)')
ylabel('Torque (nm)')
legend('Efficiency')

Output:

It can be observed from the contour that the efficiency of the motor increases with increses in speed.The efficiency is very minimal at the starting speed and increases gradually.

Result:

1. The efficiency contour of an Induction Motor is plotted.