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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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Overall efficiency <strong>of</strong> the <strong>dual</strong> <strong>stator</strong> <strong>induction</strong> machine is given by,<br />

Te ⋅ωrm<br />

η =<br />

(7.22)<br />

Re S<br />

( S ) + Re(<br />

)<br />

1<br />

2<br />

The copper loss <strong>of</strong> <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine is given as:<br />

3<br />

2 3<br />

2<br />

P copper = rs1<br />

iqds1<br />

+ rs<br />

2 iqds2<br />

(7.23)<br />

2 2<br />

The copper loss equation c<strong>an</strong> also be expressed in terms <strong>of</strong> the <strong>stator</strong> voltages as<br />

2<br />

2<br />

⎡⎛<br />

L<br />

⎞ ⎛<br />

⎞ ⎤<br />

r1<br />

Lm1<br />

Ar1Br<br />

1 Lm1<br />

Ar1ω<br />

s1<br />

⎢<br />

⎥<br />

2 2<br />

2 2<br />

3 ⎢<br />

⎜ −<br />

( ) ⎟ +<br />

⎜<br />

( ) ⎟ V<br />

1 1 1 1<br />

1 1 1<br />

⎣⎝<br />

D D Br<br />

+ ωs<br />

⎠ ⎝ D Br<br />

+ ωs<br />

⎠ ⎥<br />

P<br />

⎦<br />

copper = rs1<br />

2<br />

2<br />

2 ⎛ A ⎞ ⎛<br />

⎞<br />

s1Ar<br />

1Br1<br />

As1<br />

Ar1ω<br />

s1<br />

⎜<br />

⎜C<br />

1 2 2 ⎟<br />

⎜ 1 2 2 ⎟<br />

s −<br />

+ ωe<br />

+<br />

⎝ Br1<br />

+ ωs1<br />

⎠ ⎝ Br1<br />

+ ωs1<br />

⎠<br />

2<br />

2<br />

⎡⎛<br />

L<br />

⎞ ⎛<br />

⎞ ⎤<br />

r 2 Lm2<br />

Ar<br />

2Br<br />

2 Lm2<br />

Ar<br />

2ωs<br />

2<br />

2<br />

⎢<br />

+<br />

⎥<br />

2 2<br />

2 2<br />

2<br />

3 ⎢<br />

⎜ −<br />

2 2 ( 2 2 ) ⎟<br />

⎜<br />

2 ( 2 2 ) ⎟ Vs<br />

⎣⎝<br />

D D Br<br />

+ ωs<br />

⎠ ⎝ D Br<br />

+ ωs<br />

⎠ ⎥<br />

+ r<br />

⎦<br />

s2<br />

2<br />

2<br />

2 ⎛ A ⎞ ⎛<br />

⎞<br />

s2<br />

Ar<br />

2Br<br />

2<br />

As<br />

2 Ar<br />

2ωs<br />

2<br />

⎜<br />

⎜C<br />

2 −<br />

+<br />

2 2 ⎟<br />

⎜ 2 + 2 2 ⎟<br />

s<br />

ωe<br />

⎝ Br<br />

2 + ωs<br />

2 ⎠ ⎝ Br<br />

2 + ωs<br />

2 ⎠<br />

7.3 Steady State Analysis<br />

261<br />

2<br />

s1<br />

(7.24)<br />

In the first part <strong>of</strong> steady state <strong>an</strong>alysis, four typical steady state curves <strong>of</strong> the <strong>dual</strong><br />

<strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine---the output electromagnetic torque vs speed curve, the<br />

input <strong>stator</strong> current vs speed curve, the input power factor vs speed curve <strong>an</strong>d the<br />

efficiency vs rotor speed curve, are given. The const<strong>an</strong>t V/Hz control is applied to the<br />

machine <strong>an</strong>d the rated V/Hz value <strong>of</strong> 2.99V/Hz is used in the steady state <strong>an</strong>alysis. Since<br />

the pole ratio between the two <strong>winding</strong> sets <strong>of</strong> the <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine<br />

is 3, the input frequency ratio is normally kept to be 3 to avoid extreme losses. In the<br />

following <strong>an</strong>alysis, different values <strong>of</strong> the input voltage frequency ratio <strong>of</strong> the <strong>dual</strong> <strong>stator</strong>

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