Why does the Ns3 drop off. Fs is equall to W_s*I_s in each phase. Why does the Total Fs not include N_s3

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Why does the Ns3 drop off. 

Fs is equall to W_s*I_s in each phase.

Why does the Total Fs not include N_s3

 

Let us consider a three-phase stator winding. We will assume that the conductor
distribution for the stator windings may be expressed as
nas (Øsm) = N31 sin(Pøsm / 2) – N3 sin(3Posm
/2)
(2.5-1)
n (Øsm) = N51 sin(Pøsm / 2 – 2n / 3) – N3 sin(3PO,m / 2)
(2.5-2)
nes (Øsm) = Ng1 Ssin(Pøsm / 2+ 27t / 3)– N33 sin(3POsm / 2)
(2.5-3)
us.
In (2.5-1)–(2.5-3), the second term to the right of the equal sign (the third harmonic
term) is useful in achieving a more uniform slot fill.
In order to calculate the stator MMF for this system, we must first find the winding
function. Using the methods of Section 2.3, the winding functions may be expressed
as
2N s1
2N3
-cos(3РФ,m / 2)
ЗР
Was (Osm) =
-cos(Pom / 2)-
P
(2.5-4)
2N 53
s cos(POsm /2– 2n / 3)–-
P
Whs (Osm)=
-cos(3РФ,m / 2)
ЗР
(2.5-5)
2N31
-cos(Posm / 2 + 2n / 3)–
P
2N3
-cos(3POsm / 2)
ЗР
Wes (Øsm)=
(2.5-6)
From (2.4-17), the total stator MMF may be expressed as
Fs (Øsm) = Was (Øsm )i as + W bs (Øsm )ibs + W cs (Øsm )ies
(2.5-7)
CS
Transcribed Image Text:Let us consider a three-phase stator winding. We will assume that the conductor distribution for the stator windings may be expressed as nas (Øsm) = N31 sin(Pøsm / 2) – N3 sin(3Posm /2) (2.5-1) n (Øsm) = N51 sin(Pøsm / 2 – 2n / 3) – N3 sin(3PO,m / 2) (2.5-2) nes (Øsm) = Ng1 Ssin(Pøsm / 2+ 27t / 3)– N33 sin(3POsm / 2) (2.5-3) us. In (2.5-1)–(2.5-3), the second term to the right of the equal sign (the third harmonic term) is useful in achieving a more uniform slot fill. In order to calculate the stator MMF for this system, we must first find the winding function. Using the methods of Section 2.3, the winding functions may be expressed as 2N s1 2N3 -cos(3РФ,m / 2) ЗР Was (Osm) = -cos(Pom / 2)- P (2.5-4) 2N 53 s cos(POsm /2– 2n / 3)–- P Whs (Osm)= -cos(3РФ,m / 2) ЗР (2.5-5) 2N31 -cos(Posm / 2 + 2n / 3)– P 2N3 -cos(3POsm / 2) ЗР Wes (Øsm)= (2.5-6) From (2.4-17), the total stator MMF may be expressed as Fs (Øsm) = Was (Øsm )i as + W bs (Øsm )ibs + W cs (Øsm )ies (2.5-7) CS
To proceed further, we need to inject currents into the system. Let us consider a
balanced three-phase set of currents of the form
ins = V21, cos(@,t + ¢; )
(2.5-8)
i = V21, cos(@,t + ¢; – 2 / 3)
(2.5-9)
is
= /21, cos(@.t + ¢; +2t / 3)
(2.5-10)
%3D
where I, is the rms magnitude of each phase current, @, is the ac electrical frequency,
and ø, is the phase of the a-phase current. Substitution of (2.5-4)–(2.5-6) and (2.5-8)–
(2.5-10) into (2.5-7) and simplifying yields
-cos(POm /2– @.t – 0,)
P
Fs =
(2.5-11)
us.
Transcribed Image Text:To proceed further, we need to inject currents into the system. Let us consider a balanced three-phase set of currents of the form ins = V21, cos(@,t + ¢; ) (2.5-8) i = V21, cos(@,t + ¢; – 2 / 3) (2.5-9) is = /21, cos(@.t + ¢; +2t / 3) (2.5-10) %3D where I, is the rms magnitude of each phase current, @, is the ac electrical frequency, and ø, is the phase of the a-phase current. Substitution of (2.5-4)–(2.5-6) and (2.5-8)– (2.5-10) into (2.5-7) and simplifying yields -cos(POm /2– @.t – 0,) P Fs = (2.5-11) us.
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