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an investigation of dual stator winding induction machines

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( θ ) ⋅ g(<br />

θ,<br />

θ ) − H ( 0)<br />

⋅ g(<br />

0,<br />

)<br />

∫ H ⋅dl<br />

= H A<br />

C<br />

rm A θ rm<br />

(3.17)<br />

where, g( , θ )<br />

0 is the air gap length at the starting point <strong>an</strong>d the value <strong>of</strong> θ at the<br />

rm<br />

starting point is assumed to be zero. ( 0)<br />

while g( θ , θ ) <strong>an</strong>d ( θ )<br />

respectively.<br />

rm<br />

Substituting (3.17) into (3.15),<br />

A<br />

A<br />

H is the magnetic field at the starting point<br />

A<br />

H are the air gap length <strong>an</strong>d magnetic field at θ <strong>an</strong>gle point<br />

( θ ) ⋅ g(<br />

θ θ rm ) − H A(<br />

0)<br />

⋅ g(<br />

0,<br />

θ rm ) = nA<br />

( θ ) iA<br />

H , ⋅<br />

(3.18)<br />

An expression for the magnetic field around the <strong>stator</strong> c<strong>an</strong> be found from (3.18) as:<br />

H<br />

A<br />

( θ )<br />

n<br />

( θ ) ⋅ iA<br />

+ H A(<br />

0) ⋅ g(<br />

0,<br />

θ rm )<br />

g(<br />

θ,<br />

θ )<br />

= A<br />

(3.19)<br />

rm<br />

The H ( θ ) <strong>an</strong>d ( 0)<br />

A<br />

applied to determine the unknown qu<strong>an</strong>tity.<br />

as:<br />

H are unknown <strong>an</strong>d must be solved. Hence Gauss's Law is<br />

A<br />

If a cylinder passing through the air gap is considered, Gauss's Law c<strong>an</strong> be expressed<br />

2π<br />

∫<br />

0<br />

( θ ) r l θ = 0<br />

0 H is s<br />

µ A d<br />

(3.20)<br />

where, ris is the radius <strong>of</strong> the inner <strong>stator</strong> surface; l s is the length <strong>of</strong> the machine.<br />

Substituting (3.19) into (3.20),<br />

2π<br />

∫<br />

0<br />

( θ ) ⋅i<br />

A + H A(<br />

0)<br />

⋅ g(<br />

0,<br />

θrm<br />

)<br />

g(<br />

θ,<br />

θ )<br />

nA<br />

µ 0 ris<br />

ls<br />

dθ<br />

= 0<br />

(3.21)<br />

Rearr<strong>an</strong>ging equation (3.21) gives,<br />

rm<br />

93

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