AC Power

Contents

Example 1
Example 2

Example 1

vs = phasor2complex(170,36.87);
is = phasor2complex(5,-16.76);
S = 0.5*vs*conj(is);
fprintf('power %g (watts) %g (VAR)\n',real(S),imag(S));
phi = angle(S);
if (imag(S)>0)
    fprintf('pf %.3f lagging\n',cos(phi));
elseif (imag(S)<0)
    fprintf('pf %.3f leading\n',cos(phi));
end

power 252.024 (watts) 342.212 (VAR)
pf 0.593 lagging

Example 2

Rs = 2;
RL = 5;
Vin = 110;
CL = 2000e-6;
w=377;
ZC = 1/(j*w*CL);
ZL = RL +ZC;
fprintf('ZL %s\n',ctext(ZL));
VL  = ZL/(Rs+ZL)*Vin;
IL = VL/ZL;
S = VL*conj(IL);
fprintf('complex power %s\n',ctext(S));
fprintf('Pavg = %g (watt)\n',real(S));
fprintf('Q = %g (VAR)\n',imag(S));

ZL 5 - 1.32626j 
complex power 1191.91 - 316.156j 
Pavg = 1191.91 (watt)
Q = -316.156 (VAR)