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an investigation of dual stator winding induction machines

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Substituting δ = π into (2.97) <strong>an</strong>d assume θ = θ p is the position in which the peak<br />

air gap flux density occurs then,<br />

( p ) B cos(<br />

p )<br />

B = B cos − θ<br />

(2.98)<br />

max<br />

1<br />

1θ<br />

p 2 2<br />

p<br />

1<br />

If both sides <strong>of</strong> equation (2.98) are multiplied by , equation (2.98) becomes<br />

B<br />

B<br />

B<br />

( p ) ( p θ )<br />

B<br />

= (2.99)<br />

max 1 cos 1θ<br />

p − cos 2<br />

2 B2<br />

p<br />

B 1<br />

From (2.99), it is found that if the flux densities ratio ( ) is given <strong>an</strong>d the numbers<br />

B<br />

B1<br />

<strong>of</strong> poles <strong>of</strong> both <strong>stator</strong> <strong>winding</strong> sets are known, the value <strong>of</strong> ( p ) cos(<br />

p θ )<br />

77<br />

2<br />

2<br />

B<br />

2<br />

cos − is<br />

1θ<br />

p<br />

2<br />

fixed. Then if the peak value <strong>of</strong> the air gap flux density ( B max ) is given, the air gap flux<br />

density <strong>of</strong> each <strong>stator</strong> <strong>winding</strong> set c<strong>an</strong> be determined.<br />

The equation <strong>of</strong> Essen's rule has been given in (2.24). If the Essen’s rule is applied to<br />

two <strong>stator</strong> <strong>winding</strong> sets, the output mech<strong>an</strong>ical power equations <strong>of</strong> both <strong>winding</strong> sets are:<br />

2 ⎛ 2π<br />

⎞<br />

2<br />

PABC = α ⋅ Pmech<br />

= ⎜ ⎟<br />

⎜<br />

Ωsk<br />

11(<br />

Disle<br />

) B1K<br />

s1(<br />

rms)<br />

η gap1<br />

cosφ<br />

gap1<br />

120 ⎟<br />

(2.100)<br />

⎝ ⎠<br />

2 ⎛ 2π<br />

⎞<br />

2<br />

PXYZ = ( 1− α ) ⋅ Pmech<br />

= ⎜ ⎟<br />

⎜<br />

Ωsk<br />

12 ( Disle<br />

) B2K<br />

s2(<br />

rms)<br />

η gap2<br />

cosφ<br />

gap2<br />

120 ⎟<br />

(2.101)<br />

⎝ ⎠<br />

where, α is the mech<strong>an</strong>ical power partition factor that allocates the output powers to the<br />

two <strong>winding</strong> sets; K si(rms)<br />

is the value <strong>of</strong> the surface current density in the i <strong>stator</strong><br />

<strong>winding</strong> set; η gapi <strong>an</strong>d cos φgapi<br />

are the air gap efficiency <strong>an</strong>d the air gap power factor <strong>of</strong><br />

the i <strong>stator</strong> <strong>winding</strong> set respectively. The symbol i c<strong>an</strong> be either the ABC <strong>winding</strong> set or<br />

p

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