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an investigation of dual stator winding induction machines

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* ( i )<br />

3 Pi<br />

Tei = Im λqdsi<br />

qdsi<br />

(7.17)<br />

2 2<br />

where, * represents complex conjugation <strong>of</strong> variables.<br />

The total electromagnetic torque <strong>of</strong> the <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine is the<br />

sum <strong>of</strong> the torques due to the two <strong>stator</strong> <strong>winding</strong> sets, which c<strong>an</strong> be expressed as:<br />

* 3 P2<br />

*<br />

( λ i ) + Im(<br />

i )<br />

3 P<br />

= (7.18)<br />

2 2<br />

2 2<br />

1<br />

Te Te1<br />

+ Te2<br />

= Im qds1<br />

qds1<br />

λqds2<br />

qds2<br />

Then by substituting (7.15) <strong>an</strong>d (7.16) into (7.18), the torque equation c<strong>an</strong> be<br />

expressed in terms <strong>of</strong> the input voltages, input frequencies <strong>an</strong>d machine parameters as:<br />

T<br />

e<br />

=<br />

3 P1<br />

L<br />

2 2 D<br />

m1<br />

1<br />

3 P2<br />

L<br />

+<br />

2 2 D<br />

m2<br />

2<br />

( )<br />

( ( ) ) ( ( ) )<br />

(<br />

( )<br />

( ) ) ( ( ) ) 2<br />

2 2 2<br />

Ar1ω<br />

s1Vs1<br />

Br1<br />

+ ωs1<br />

2 2<br />

2<br />

2 2<br />

2<br />

Cs1<br />

Br1<br />

+ ωs1<br />

− As1Ar<br />

1Br1<br />

+ ωe1<br />

Br1<br />

+ ωs1<br />

+ As1A<br />

r1ωs1<br />

C<br />

2 2 2<br />

Ar<br />

2ωs<br />

2Vs<br />

2 Br<br />

2 + ωs<br />

2<br />

2 2<br />

2<br />

2 2<br />

B + ω − A A B + ω B + ω + A A ω<br />

s2<br />

r 2<br />

s2<br />

s2<br />

r 2<br />

r 2<br />

260<br />

e2<br />

r 2<br />

s2<br />

s2<br />

r 2<br />

s2<br />

(7.19)<br />

If the machine parameters are assumed to be const<strong>an</strong>t at <strong>an</strong>y operating condition <strong>an</strong>d<br />

the const<strong>an</strong>t V/Hz control is applied to the machine, the variables in equation (7.19) are<br />

electromagnetic torque T e , rotor mech<strong>an</strong>ical speed ω rm , electric speed <strong>of</strong> the ABC<br />

<strong>winding</strong> set ω e1<br />

<strong>an</strong>d electric speed <strong>of</strong> the XYZ <strong>winding</strong> set e2<br />

ω . It should be noticed that<br />

only three <strong>of</strong> them are independent, which me<strong>an</strong>s that if <strong>an</strong>y three <strong>of</strong> them are known, the<br />

last one is also fixed.<br />

The complex power equation <strong>of</strong> the machine is given by<br />

* ( V I )<br />

3<br />

S i = qdsi qdsi<br />

(7.20)<br />

2<br />

The power factor <strong>of</strong> the <strong>dual</strong> <strong>stator</strong> <strong>induction</strong> machine c<strong>an</strong> then be expressed as:<br />

( Si<br />

)<br />

( S )<br />

Re<br />

Power Factor ( PF)<br />

= (7.21)<br />

Abs<br />

i

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