Page 244 - Solutions Manual to accompany Electric Machinery Fundamentals

e_a = v_t - i_a * r_a;

% Calculate the effective field current.
i_f = v_t / (r_f + r_adj);

% Calculate the resulting internal generated voltage at
% 1200 r/min by interpolating the motor's magnetization
% curve.
e_ a0 = interp1(if_values,ea_values,i_f);

% Calculate the resulting speed from Equation (9-13).
n = ( e_a ./ e_a0 ) * n_0;

% Calculate the induced torque corresponding to each
% speed from Equations (8-55) and (8-56).
t_ind = e_a .* i_a ./ (n * 2 * pi / 60);

% Plot the torque-speed curves
figure(1);
plot(t_ind,n,'b-','LineWidth',2.0);
xl abel('\bf\tau_{ind} (N-m)');
ylabel('\bf\itn_{m} \rm\bf(r/min )');
title ('\bfS hunt DC Motor Torque-Speed Characteristic');
axis([ 0 80 2700 3000]);
grid on;
The resulting torque-speed curve is shown below:

(e) If R is maximum at no-load conditions, the total resistance is 500 , and
adj
V 240 V
I  F T   0.48 A
R  F R adj 200 300 


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