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Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...

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Modeling and control modes <strong>of</strong> PM synchronous motor drives<br />

Substituting to above equations the following expressions for complex vectors<br />

U U jU<br />

sxy<br />

=<br />

sx<br />

+<br />

sy, Isxy<br />

Isx jIsy<br />

= + , Ψ =Ψ<br />

s<br />

and splitting into real and imaginary parts<br />

sxy<br />

one can obtain the scalar form <strong>of</strong> the machine equations in stationary x,<br />

y reference<br />

frame:<br />

U<br />

dΨ<br />

dt<br />

s<br />

sx<br />

= Rs Isx<br />

+ (2.27a)<br />

U = R I +ΩΨ<br />

Ψ (2.27b)<br />

sy s sy s<br />

s<br />

1 1<br />

Ψ<br />

s<br />

= [( Ld + Lq) −( Lq − Ld)cos 2 δΨ ] Isx<br />

+ ( Lq − Ld)sin 2δΨIsy<br />

+Ψ<br />

PM<br />

cosδΨ<br />

2 2<br />

(2.28a)<br />

1 1<br />

0 = ( Lq − Ld)sin2 δΨIsx<br />

+ [( Ld + Lq) + ( Lq −Ld)cos2 δΨ] Isy<br />

−Ψ<br />

PM<br />

sinδΨ<br />

2 2<br />

(2.28b)<br />

The current-flux equations can be expressed also in simplest form as:<br />

2 2<br />

s<br />

( Ld cos δΨ Lqsin δΨ) Isx<br />

( Lq Ld)sinδΨcosnδΨIsy<br />

PM<br />

cosδΨ<br />

Ψ = + + − +Ψ (2.29a)<br />

2 2<br />

q d<br />

δΨ δΨ sx d<br />

δΨ q<br />

δΨ sy PM<br />

δΨ<br />

0 ( L L )sin cos I ( L sin L cos ) I sin<br />

= − + + −Ψ (2.29b)<br />

Rotor flux fixed system ( dq) ,<br />

In order to take advantage <strong>of</strong> the set <strong>of</strong> equations (2.19) and (2.20) in rotating coordinate<br />

system, one assumes that the coordinate system rotates <strong>with</strong> the rotor flux angular speed<br />

Ω<br />

K<br />

= pbΩ m<br />

and θK = pbγm = θr<br />

d Ψ<br />

U<br />

sdq<br />

R I jp<br />

dt<br />

sdq<br />

s sdq<br />

b m<br />

= + + Ω Ψ (2.30)<br />

sdq<br />

Ld + Lq Lq −Ld<br />

∗<br />

Ψ<br />

sdq<br />

= ( ) Isdq − ( ) Isdq<br />

+Ψ<br />

PM<br />

(2.31)<br />

2 2<br />

Substituting the following expressions for complex vectors U = Usd + jUsq,<br />

I I jI<br />

sdq<br />

=<br />

sd<br />

+<br />

sq, sdq sd<br />

j<br />

sq<br />

Ψ =Ψ + Ψ to (2.30) and (2.31), and splitting for real and<br />

imaginary parts the scalar form <strong>of</strong> the machine equations in rotational fixed reference<br />

frame can be obtained:<br />

dΨ<br />

sd<br />

Usd = Rs Isd + − pbΩmΨ sq<br />

(2.32a)<br />

dt<br />

sdq<br />

15

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