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an investigation of dual stator winding induction machines

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qsi<br />

qsi<br />

* ( I I )<br />

σ = K ⋅ −<br />

(10.33)<br />

dsi<br />

dsi<br />

qsi<br />

qsi<br />

* ( I I )<br />

σ = K ⋅ −<br />

(10.34)<br />

dsi<br />

dsi<br />

* ( λ )<br />

σ −<br />

ri = K ri ⋅ ri λri<br />

σ ω ω<br />

* ( ω − )<br />

= K ⋅ ω<br />

rm<br />

rm<br />

351<br />

(10.35)<br />

(10.36)<br />

Where, K qsi , K dsi , K ri <strong>an</strong>d K ω are the tr<strong>an</strong>sfer functions <strong>of</strong> controllers for q-axis<br />

current, d-axis current, rotor flux <strong>an</strong>d rotor speed respectively. The traditional PI<br />

controller structure is used for all the controllers.<br />

Since the nonlinear terms <strong>of</strong> the system model have been embedded in the nonlinear<br />

controllers, the system is linearized <strong>an</strong>d linear system control methodologies c<strong>an</strong> be used<br />

to determine the parameters <strong>of</strong> the controllers.<br />

The d-axis <strong>stator</strong> current comm<strong>an</strong>d is determined from (10.31):<br />

* Lri<br />

idsi = σ ri<br />

r L<br />

ri<br />

mi<br />

The desired q- <strong>an</strong>d d-axis voltages are calculated from (10.29-10.30) as:<br />

ω L<br />

*<br />

ri mi<br />

Vqsi = σ qsi + ωeiLσ<br />

iI<br />

dsi + λri<br />

Lri<br />

*<br />

dsi<br />

ri mi<br />

σ dsi − ωei<br />

σi qsi − 2<br />

Lri<br />

ri<br />

(10.37)<br />

(10.38)<br />

r L<br />

V = L I λ<br />

(10.39)<br />

The calculation <strong>of</strong> q-axis <strong>stator</strong> current comm<strong>an</strong>d needs the speed controller output.<br />

However, it should be noticed that the two <strong>stator</strong> <strong>winding</strong> sets have the same rotor<br />

mech<strong>an</strong>ical speed such that the q-axis <strong>stator</strong> current comm<strong>an</strong>ds <strong>of</strong> both <strong>winding</strong> sets have<br />

to share the same speed controller output. A variable coefficient called torque distribution<br />

factor K is introduced to partition the electromagnetic torque for each <strong>winding</strong> set.

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