Page 164 - Solutions Manual to accompany Electric Machinery Fundamentals

nm = (1 - s) * n_sync; % Mechanical speed

% Calculate torque versus speed
for ii = 1:51
t_ind(ii) = (3 * v_th^2 * r2 / s(ii)) / ...
(w_sync * ((r_th + r2/s(ii))^2 + (x_th + x2)^2) );
end

% Plot the torque-speed curve
figure(1);
plot(nm,t_ind,'k-','LineWidth',2.0);
xlabel('\bf\itn_{m}');
ylabel('\bf\tau_{ind}');
title ('\bfInduction Motor Torque-Speed Characteristic');
grid on;
The resulting plot is shown below:

(b) A MATLAB program to calculate the output-power versus speed curve is shown below.

% M-file: prob6_7b.m
% M-file create a plot of the output pwer versus speed
% curve of the induction motor of Problem 6-5.

% First, initialize the values needed in this program.
r1 = 0.100; % Stator resistance
x1 = 0.210; % Stator reactance
r2 = 0.070; % Rotor resistance
x2 = 0.210; % Rotor reactance
xm = 10.0; % Magnetization branch reactance
v_phase = 208 / sqrt(3); % Phase voltage
n_sync = 1800; % Synchronous speed (r/min)
w_sync = 188.5; % Synchronous speed (rad/s)

% Calculate the Thevenin voltage and impedance from Equations
% 6-41a and 6-43.
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