Page 229 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS

216 Renewable Energy Devices and Systems with Simulations in MATLAB and ANSYS ®
®

Open stator
slot

g Semiopen

(a) rotor slot
Airflow
Axial channels Radial
(air flow) channels
(air flow)
Airgap Airgap
(air flow) (air flow)
Axial channels
(air flow)

Air flow Air flow
(b)

FIGURE 9.6 Layout of DFIG: (a) stator and rotor laminations, rotor and stator slotting; (b) stator and rotor
stacks for axial and radial–axial cooling.

R (1–S) V (1–S)
r
r
1 r1
I s R s jω L I r jω L R r S S
1 s1
I m
V s R 1m jω L V r
1 1m

FIGURE 9.7 DFIG electrical equivalent circuit.

Adding the flux/current relationships for stator flux, ψ , and rotor flux, ψ ,
s
r
L L 2
ψ = ψ m + L I ; r L = L m + rl L ; L sc = s L − m ≈ sl L + rl L (9.8)
sc s
s r r L r L
Equations 9.6 and 9.7 then become
ψ − IL m
I = r s (9.9)
r
L r