ex9_3.m

美国 A.E.Fitgerald著 刘新正,苏少平,高琳翻译,第六版的源代码

% Example 9.3

clc
clear

% Useful constants
f = 60;			%60 Hz system
omega = 2*pi*f;
s = 0.05;		% slip

% Parameters

R1 = 0.534;
X1 = 2.45;
Xm = 70.1;
R2 = 0.956;
X2 = 2.96;

% Winding voltages

Valpha = 230;
Vbeta = 210 * exp(j*80*pi/180);

%(a)  Calculate Vf and Vb from Equations
% 9-21 and 9-22

Vf = 0.5*(Valpha - j*Vbeta);
Vb = 0.5*(Valpha + j*Vbeta);

magVf = abs(Vf);
angleVf = angle(Vf)*180/pi;

magVb = abs(Vb);
angleVb = angle(Vb)*180/pi;

fprintf('\n(a)')
fprintf('\n  Vf = %.1f + j %.1f  = %.1f at angle %.1f degrees V', ...
	real(Vf),imag(Vf),magVf,angleVf);
fprintf('\n  Vb = %.1f + j %.1f  = %.1f at angle %.1f degrees V\n', ...
	real(Vb),imag(Vb),magVb,angleVb);

%(b) First calculate the forward-field input impedance of the motor 
% from the equivalent circuit of Fig. 9-12 (a)

Zforward = R1 + j*X1 + j*Xm*(R2/s+j*X2)/(R2/s+j*(X2+Xm));

%Now calculate the forward-field current.

If = Vf/Zforward;

magIf = abs(If);
angleIf = angle(If)*180/pi;

% Next calculate the backward-field input impedance of the motor 
% from the equivalent circuit of Fig. 9-12 (b)

Zback = R1 + j*X1 + j*Xm*(R2/(2-s)+j*X2)/(R2/(2-s)+j*(X2+Xm));

%Now calculate the backward-field current.

Ib = Vb/Zback;

magIb = abs(Ib);
angleIb = angle(Ib)*180/pi;

fprintf('\n(b)')
fprintf('\n  If = %.1f + j %.1f  = %.1f at angle %.1f degrees A', ...
	real(If),imag(If),magIf,angleIf);
fprintf('\n  Ib = %.1f + j %.1f  = %.1f at angle %.1f degrees A\n', ...
	real(Ib),imag(Ib),magIb,angleIb);

%(c) Calculate the winding currents from Eqs. 9-19 and 9-20

Ialpha = If + Ib;

Ibeta = j*(If - Ib);

magIalpha = abs(Ialpha);
angleIalpha = angle(Ialpha)*180/pi;

magIbeta = abs(Ibeta);
angleIbeta = angle(Ibeta)*180/pi;

fprintf('\n(c)')
fprintf('\n  Ialpha = %.1f + j %.1f  = %.1f at angle %.1f degrees A', ...
	real(Ialpha),imag(Ialpha),magIalpha,angleIalpha);
fprintf('\n  Ibeta = %.1f + j %.1f  = %.1f at angle %.1f degrees A\n', ...
	real(Ibeta),imag(Ibeta),magIbeta,angleIbeta);

%(d) Power delivered to the forward field is equal to the 
% forward-field input power less the stator-winding I^2R loss

Pgf = 2*(real(Vf*conj(If)) - R1*magIf^2);

% Power delivered to the backward field is equal to the 
% backward-field input power less the stator-winding I^2R loss

Pgb = 2*(real(Vb*conj(Ib)) - R1*magIb^2);

% The electromagnetic power is equal to (1-s) times the 
% net air-gap power

Pmech = (1-s)*(Pgf - Pgb);

fprintf('\n(d)')
fprintf('\n  Power to forward field = %.1f W',Pgf)
fprintf('\n  Power to backward field = %.1f W',Pgb)
fprintf('\n  Pmech = %.1f W\n',Pmech)
fprintf('\n')