Sinusoid-phasor Transformation

Monday, 17 September 2018

1:45 PM

Phasors are defined in cosine form, so other sinusoid forms need to be converted to their cosine form

 

Machine generated alternative text:
Time-domain representation 
v(t) 
= Vm cos(wt + (P) 
v(t) 
= Vm sin(wt + (P) 
v(t) = —Vm cos(wt + 4) 
v(t) = —Vim sin(wt + 4) 
i(t) = 1m cos(wt + O) 
i(t) = 1m sin(wt + 9) 
i(t) = —1m cos(wt + 9) 
i(t) — 
— —1m sin(wt + O) 
Phasor-domain representation 
V = VmL(Ø — 900) 
V = VmL(Ø ± 1800) 
V = vmL@ + 900) 
1 = 1mL(9 — 900) 
1 = 1mL(9 ± 1800) 
1 = 1mL(9 + 900)

 

Machine generated alternative text:
• We can find the relationship between linear mathematical operations in time 
domain and their transformation in phasor domain. 
Differentiating a sinusoid is equivalent to multiplying its corresponding 
phasor by jü). 
Consider a sinusoid and its corresponding phasor: 
v(t) = Vm cos(ot+ 4) V = VmLØ 
Take time derivative of the sinusoid: 
dv 
— —wVm sin(ot + 4) 
dt ¯ 
= (DVm cos(wt + + 900) 
= = Re Vmejqb ejwt ej900 = Re(jwVejwt) 
v 
dv 
dt 
(Time domain) 
jov 
(Phasor domain)

 

 

Created with Microsoft OneNote 2016.