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an investigation of dual stator winding induction machines

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controlled variables with each output-input pair decoupled from each other. The control<br />

variables are M qs1,<br />

M ds1<br />

<strong>an</strong>d qs2<br />

M , M ds2<br />

while the controlled variables are dc voltage<br />

V dc , the rotor flux linkages <strong>of</strong> the 2-pole ABC <strong>winding</strong> λ qr1<br />

<strong>an</strong>d dr1<br />

linkages <strong>of</strong> the 6-pole XYZ <strong>winding</strong> λ qr 2 <strong>an</strong>d dr2<br />

296<br />

λ <strong>an</strong>d the rotor flux<br />

λ . The above input-output linearization<br />

algorithm is simplified as a three-step process: (a) differentiate a controlled variable until<br />

<strong>an</strong> input variable appears, (b) choose the input variables to c<strong>an</strong>cel nonlinear terms <strong>an</strong>d<br />

guar<strong>an</strong>tee tracking convergence, <strong>an</strong>d (c) study the stability <strong>of</strong> the internal dynamics. The<br />

total number <strong>of</strong> differentiations for all controlled variables is called the relative order r,<br />

while the internal dynamics are composed <strong>of</strong> n-r states (n is the total number <strong>of</strong> the<br />

system dynamic states).<br />

When operations (a-c) are performed on equations (8.1-8.9), the resulting equations<br />

are linearized <strong>an</strong>d decoupled hence the system is input-output linearizable, decoupled<br />

with no internal dynamics. Any realistic dynamics c<strong>an</strong> be imposed by me<strong>an</strong>s <strong>of</strong> linear<br />

controllers.<br />

Multiplying (8.9) with V dc gives:<br />

( Vqs1iqs1<br />

+ Vds1ids1<br />

+ Vqs2iqs2<br />

+ Vds2ids<br />

) = dc<br />

1 V<br />

CpV σ<br />

2<br />

2<br />

dc +<br />

2<br />

dc = 3<br />

RL<br />

2<br />

(8.33)<br />

Assume the power ratio between the 6-pole XYZ <strong>winding</strong> set to the 2-pole <strong>winding</strong><br />

set is K :<br />

( V i V i ) = K ⋅ ( V i + V i )<br />

+ (8.34)<br />

qs 2 qs 2 ds 2 ds 2<br />

qs1<br />

qs1<br />

ds1<br />

ds1<br />

Then the relationship between σ <strong>an</strong>d the two controlled variables to the 2-pole ABC<br />

dc<br />

<strong>an</strong>d 6-pole XYZ <strong>winding</strong> sets respectively are:

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