Transcript HIGH PERFORMANCE DIRECT TORQUE CONTROL INDUCTION …

Field-Oriented Control of
Induction Machine
Dr. Nik Rumzi Nik Idris
Department of Energy Conversion,
Faculty of Electrical Engineering,
Universiti Teknologi Malaysia
Why FOC ?
• IM is superior to DC machine with respect to
size, weight, inertia, cost, speed
• DC motor is superior to IM with respect to ease
of control
– High performance with simple control due de-coupling
component of torque and flux
• FOC transforms the dynamics of IM to become
similar to the DC motor’s – decoupling the
torque and flux components
Basic Principles DC machine
By keeping flux constant,
torque can be controlled
by controlling armature
current
a
Te = k If Ia
f
Current in
Current out
Basic Principles of IM
s
c’
b
a
r
b’
c
Stator current produce stator
flux
Stator flux induces rotor
current  produces rotor
flux
Interaction between stator
and rotor fluxes produces
torque
Space angle between stator
and rotor fluxes varies with
load, and speed
FOC of IM drive
Torque equation :
3p
Te 
 s  is
22
3 p Lm
Te 
 r  is
2 2 Lr
In d-q axis :
3 p Lm
Te 
( rd i sq   rq i sd )
2 2 Lr
FOC of IM drive
In d-q axis :
3 p Lm
Te 
( rd i sq   rq i sd )
2 2 Lr
Choose a frame such that:

r
rd
 r
 rq  0
r
FOC of IM drive
Choose a frame such that:

r
rd
 r
 rq  0
r
FOC of IM drive
Choose a frame such that:
 rd  r
 rq  0
r
r
qs
As seen by stator reference frame:
3 p Lm
Te 
( rd i sq   rq i sd )
2 2 Lr
is
isq
r
rq
isd
rd
ds
FOC of IM drive
Choose a frame such that:
 rd  r
 rq  0
r
r
qs
Rotating reference frame:
qr
is
Te 
3 p Lm
r
(r rdisq
i sq   rq i sd )

2 2 Lr
r
r
isq
dr
r
isd
ds
FOC of IM drive
To implement rotor flux FOC need to know rotor flux position:
(i)
Indirect FOC
Synchronous speed obtain by adding slip speed and rotor speed
Rotor voltage equation:
Rotor flux equation:
drg
0R i 
 j(g  r )rg
dt
rg  L r irg  L m isg
g
r r
R r g L m R r g d rg
0
r 
is 
 j(g  r ) rg
Lr
Lr
dt
0


Rr
L R r
d r
r
 r  m r i sd
 jisq

 j(slip) r
Lr
Lr
dt
FOC of IM drive - indirect
q component
d component
Rr
L m R r  r d r
0
r 
i sd 
Lr
Lr
dt
0

0

L mR r  r
isq  (slip) r
Lr
Rr
L R r
d r
r
 r  m r i sd
 jisq

 j(slip) r
Lr
Lr
dt
FOC of IM drive - indirect


Rr
L m R r r
d r
r
0
r 
i sd  jisq 
 j(slip) r
Lr
Lr
dt
q component
d component
Rr
L m R r  r d r
0
r 
i sd 
Lr
Lr
dt

i *
Lm
r
sd
*
r
0
L mR r  r
isq  (slip) r
Lr
L R r
(slip )  m* r isq
 rL r
4Te* L r
i *
3p r L m
r
sq
FOC of IM drive - indirect
T*
*
r
isd
*
r
isq
*
 *r
Lm
4Te* L r
3p r L m
(slip ) 
irsq*
ir
sd*
ia*
isq*
ej
isd*
2/3
ic*
L mR r r
isq
 *rL r
1/s
slip
r
+
Rotating frame
ib*
+
Stationary frame
CC
VSI
FOC of IM drive
(ii)
Direct FOC
Rotor flux estimated from motor’s terminal variables
Rotor flux can be estimated by:
0
Rr
L R
d r
 r  m r is 
 jr  rg
Lr
Lr
dt
Te 
3 p Lm
r  is
2 2 Lr
Express in stationary frame
FOC of IM drive
(ii)
Direct FOC
0
Rr
L R
d r
r  m r is 
 jr rg
Lr
Lr
dt
0
d(rd  jrq )
Rr
L R
(rd  jrq )  m r (isd  jisq )i 
 jr (rd  jrq )
Lr
Lr
dt
q
d
 rd
 Rr

L mR r

 
 rd 
isd  r  rq dt
Lr
 Lr


  
 rq
 rd
R

L R
 rq   r  rq  m r isq  r  rd dt
Lr
 Lr


  r   2rd   2rq
FOC of IM drive - direct
T*
TC
r*
FC
irsq*
irsd*
ia*
isq*
ej
ib*
2/3
isd*
ic*
CC
VSI
r
Te

0
Rr
L R
d r
 r  m r is 
 jr  rg
Lr
Lr
dt
Te 
Rotating frame
Stationary frame
3 p Lm
r  is
2 2 Lr