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an investigation of dual stator winding induction machines

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2π<br />

where, α = is the bar spacing <strong>an</strong>gle,<br />

r<br />

N r<br />

the magnitude <strong>of</strong> the<br />

as:<br />

C<br />

where,<br />

k<br />

R<br />

1<br />

= k<br />

π ⋅ r<br />

k<br />

wR<br />

'<br />

θ is the <strong>an</strong>gle in rotor reference frame;<br />

202<br />

k<br />

C R is<br />

th<br />

k harmonics <strong>winding</strong> distribution <strong>an</strong>d its peak value is expressed<br />

k<br />

k wR is the <strong>winding</strong> factor <strong>of</strong> a loop for<br />

th<br />

k harmonics <strong>winding</strong> distribution.<br />

(5.32)<br />

Then the flux density <strong>an</strong>d electric field due to the currents flowing in the ABC<br />

<strong>winding</strong> set expressed in the rotor reference frame are given as:<br />

[ ] ⎬<br />

⎭ ⎫<br />

s1<br />

s1<br />

⎧<br />

'<br />

' µ 0r<br />

j<br />

( ) =<br />

( ⋅ ) ( s1ω1t<br />

−P1<br />

θ<br />

θ , t Re j 2 3C<br />

I e<br />

)<br />

B r1<br />

⎨<br />

(5.33)<br />

⎩ gP1<br />

[ ] ⎬<br />

⎭ ⎫<br />

s1<br />

s1<br />

2<br />

⎧<br />

'<br />

'<br />

µ 0s1ω1r<br />

j<br />

( ) = −<br />

( ⋅ ) ( s1ω1t<br />

−P1<br />

θ<br />

θ , t Re j 2 3C<br />

I e<br />

)<br />

E r1<br />

⎨<br />

(5.34)<br />

2<br />

⎩ gP1<br />

The slip frequency s 1 is defined as:<br />

ω1 − P1ω<br />

r<br />

s1<br />

= (5.35)<br />

ω<br />

1<br />

where, ω r is the rotor mech<strong>an</strong>ical speed.<br />

The induced EMF in the th<br />

i rotor loop due to currents flowing in the ABC <strong>winding</strong><br />

set is obtained by multiplying the th<br />

i rotor loop <strong>winding</strong> distribution function with the<br />

electric field function as:<br />

2π<br />

'<br />

'<br />

() t = rl ∫ CRi<br />

( θ ) ⋅ E 1(<br />

θ t)<br />

'<br />

rpi , dθ<br />

(5.36)<br />

u r<br />

0<br />

Substituting the expression <strong>of</strong> the th<br />

i rotor loop <strong>winding</strong> distribution <strong>an</strong>d the electric<br />

field into (5.36) to yield,

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