spwave.m

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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  spwave.m - simulates the component forward & backward 
%             air gap mmf waves of a single-phase induction    
%             motor for one magnetic pole-pair pitch of
%             movement in 10 magnetic (electric) degree
%             increments. Components are then added to give
%             resultant air gap standing wave.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clear; colordef white;
p=input('How many poles    ');   % No. of poles
theta=linspace(0,2*pi,50); n=length(theta);
ro=6; rs=5; rr=4;  % Outside, bore, & rotor radii
rgr=4.5;           % Air gap center grid radius
Ro=ro*ones(1,n);Rs=rs*ones(1,n);Rgr=rgr*ones(1,n);Rr=rr*ones(1,n);
F=zeros(1,n); F1=F; F2=F; phi=pi/4;
for i=1:37; pause(0.001);
   polar(theta,Ro,'-.'); hold on; polar(theta,Rs,'-.');
   polar(theta,Rgr,'m'); polar(theta,Rr,'g-.');
for j=1:n; 
F1(j)=Rr(j)+0.5+0.225*cos(p/2*theta(j)-phi);
F2(j)=Rr(j)+0.5+0.225*cos(p/2*theta(j)+phi);
F(j)=F1(j)+F2(j)-Rr(j)-0.5; end
polar(theta,F,'r'); polar(theta,F1,'y:'); polar(theta,F2,'c-.');
text(0.9,rs+0.25,'Stator');text(-1.5,rr-0.75,'Rotor');
text(5.5,5,'.. Forward');text(5.5,4,'-. Backward');
text(5.5,6,'- Resultant');
name=['Air gap mmf waves of single-phase induction motor';
   '                                                 ';
   '                                                 ']; title(name);
phi=phi+pi/18; hold off;
end