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SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

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FR NRiR R iR<br />

(A.2)<br />

R R<br />

<br />

Ni Ni<br />

R R<br />

S S R R<br />

T S R (A.3)<br />

The total flux linked by the stator and rotor winding is given by Equations (A.4) and (A.5).<br />

NSNR S NST NS iS iR<br />

R R <br />

<br />

NN S S NN S R<br />

iS iR<br />

(A.4)<br />

R R<br />

NSNR R NRT NR iS iR<br />

R R <br />

<br />

NRNS NRNR iS iR<br />

(A.5)<br />

R R<br />

Inductance is defined as the amount of flux linked by a winding per amount of current, thus the<br />

terms that multiply the currents in Equations (A.4)-(A.5) are inductances. The inductances<br />

N N R and ( N N / R ) are self inductances because they describe flux linkage in a circuit<br />

( / )<br />

S S<br />

R R<br />

due to current in the same circuit. The inductances ( / )<br />

S R<br />

N N R and ( N N / R ) are mutual<br />

inductances because they describe flux linkage in a circuit due to current in another circuit. The<br />

total flux linkage equations can be written in terms of self and mutual inductances in matrix form<br />

as Equation (A.6).<br />

S LSS LSR iS<br />

<br />

<br />

<br />

R LRS L<br />

<br />

RR i<br />

<br />

<br />

R<br />

R S<br />

(A.6)<br />

Recognizing that the product of inductance and current is flux linkage, the total flux linkage<br />

equations can be written in terms of self and mutual flux linkages as Equation (A.7).<br />

<br />

<br />

S SS SR <br />

<br />

<br />

<br />

R RS <br />

<br />

RR<br />

<br />

(A.7)<br />

In a permanent magnet brushless motor flux passes through the rotor but there is no winding on<br />

the rotor. Therefore there is no rotor current and there is no rotor flux linkage R , so Equations<br />

(A.6) and (A.7) simplify to Equations (A.8) and (A.9), respectively.<br />

270

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