WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
DIRECT TORQUE CONTROL METHODS
FOR PWM INVERTER-FED INDUCTION
MOTOR DRIVES  A SURVEY
Marian P. Kazmierkowski
Institute of Control and Industrial Electronics
Warsaw University of Technology
PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
OUTLINE
" Introduction
" Basic concepts
" Generic DTC scheme
" Switching Table DTC (ST-DTC)
" Basic DSC scheme
" Constant switching frequency DTC
" Variants of DTC-SVM
" Selected results
" Conclusions
PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Variable
Frequency
Control
Scalar based Vector based
controllers controller
Feedback Direct Torque Passivity
is = f(�r )
U/f=const Field Oriented
Linearisation Control Based Control
Direct Torque Circle flux Hexagon flux
Rotor Flux Stator Flux
Space - Vector trajectory trajectory
Oriented Oriented
Modulation (Takahashi) (Depenbrock)
Open Loop Closed Loop
Direct Indirect
NFO Flux & Torque
(Blaschke) (Hasse)
..
(Jonsson) Control
Classification of IM control methods
Marian P. Kazmierkowski
PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Remark
Since there is no commonly shared terminology
regarding DTC, in this work under DTC scheme
we refer to control schemes operating with closed
torque and flux loops without current controllers.
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
(a) (b)
� �
�s
is
CC-PWM-VSI PWM-VSI
�r
�� �r
�
�s
us
is
ą ą
IM IM
�r �r
lM lM
lr
lr
me me
is �
1
s
� ls
sin� sin��
Torque production: (a) field-oriented control, (b) direct torque control
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a) b)
�
B
u3(010) u2(110)
111
Udc u1(100)
u7(111)
000
u0(000)
u4(011) ą A
UA UB UC
u6(101)
u5(001)
C
(a) Simplified diagram of the VS inverter feeding an induction motor; (b)
representation of output voltage vectors
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a) b)
� �
�
�
s
s
ą
ą
Stator flux path in ą-� plane (a) under six-step operation and (b) under
sinusoidal PWM operation (low switching frequency)
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
moment with active
forward vector
q
stops with zero
vector
+ Hm
moment with active
me ~ �
sq
�s
backward vector
- Hm
��
�r
rotates
continuously
d
stator
ą
Stator flux vector movement relative to rotor flux vector
under the influence of active and zero voltage vectors
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a)
Flux
Controller
�
sc
Active
�
s
Vectors
SA uA
isą
Voltage VS
SB uB
Induction
is�
Vector PWM
Motor
SC uC
Selection Inverter me
mc
Zero
Vectors
�(łs)
Torque
Controller
Flux Current
b)
Controller
Coordinate
�
Transformation
~ isdc
sc
PI
�
s
U Usąc SA uA
sdc
d - q
isą
VS
SB uB
Induction
is�
Torque Current
SVM PWM
Motor
Us�c SC uC
Controller
Inverter me
ą - �
U
sqc
mc ~ i
sqc
PI
ł
sin r
cos
i
sq
ą - �
isd
d - q
Two schemes of PWM inverter-fed induction motor with: a) direct
torque and stator flux control (DTC), b) field oriented control (FOC)
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
PEMC  94: K. Hasse, B.K. Bose, M.P. Kazmierkowski
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a) b)
sector 2
� �
sector 3 sector 2
u2
u2
u3
u3
sector 3 sector 1
u1 u7 u1
u7
sector 4 sector 1
u0
u0
u4
ą u4 ą
sector 4 sector 6
u6
u6
u5
u5
sector 5 sector 6
sector 5
Sector definition for circular (a) and hexagonal (b) stator flux
vector path
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
IECON  97: P.Z. Grabowski, I. Takahashi, M.P. Kazmierkowski
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a)
b)
Flux
Udc
us �
Controller
�
d�
sc
m
e
SA
Vector
SB
Selection
SC
Table
dm
mc
is �
N(ł )
s
Torque
Sector Voltage
Controller
Detection Calculation
�
�
są s�
me
us
Flux and
is
Torque
�
s
estimator
Motor
Switching Table Based DTC with circular stator flux path according to
Takahashi and Nogouchi (a) block scheme, (b) transient response to
rated torque reversal
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a) b)
sector 4 sector 3
� �
u4
sector 5 sector 2
u3
u4
u5
u2
u6
sector 1+
sector 6 sector 1
u1
u7
ą ą
sector 7
u12 sector 12 sector 1-
u8
u8
u11
sector 8 sector 12
u9
u10
sector 9 sector 10
Voltage vectors generated with two (a) and three (b) equal
time intervals per cycle period
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Bachum  96: A.Steimel, M.P. Kazmierkowski, M. Depenbrock
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
a) b)
Flux
us�
Comparators
�
Udc
sc d
B me
"�
s
SA
d
A SB
PI
is�
SC
mc
dż
dC
Torque
Voltage
Controller
Calculation
�
s�A
�
A B C są
�
s�B
us
Flux and
�
s�
�
is
s�C Torque
ą �
me
estimator
Motor
DSC with hexagonal stator flux path according to Depenbrock (a)
block scheme (b) transient response to rated torque reversal
Marian P. Kazmierkowski
PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
(a) (b)
S / H
1/Ts
mc + Hm
mc
mc - Hm
t1 t2 t3
Ts Ts Ts
Operation of the analog (a) and discrete (b) hysteresis controller
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
� �
SA
rc sdc
d - q
�s TN usc
�sc " SB
Eqs (16) SVM
�sqc
mc TS
SC
ą - �
�s
rs
łr
Udc
us
Rotor Flux Stator Flux Voltage
Calculation
Estimator Estimator
iA
ą - �
is
iB
ABC
DTC-SVM with closed flux control [D. Casadei et.al.]
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
�sc
Torque
Controller SA
mc usc
"�� �sc �s TN
SB
"
Eq. (18) SVM
PI
TS
SC
�
s
rs
m
ł
s
Flux and
Udc
us
Voltage
Torque
Calculation
Estimator
iA
ą - �
is
iB
ABC
DTC-SVM with closed loop torque control [L.Xu, M.Fu]
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Flux
Controller
�sc k�
SA
P
�s TN
" usc
SB
Eq. (21) SVM
TS
"ł
SC
s
mc
"łsd
PI
rs
ł
s
"ł
Torque
ss
Controller �s
Flux and
Udc
us
Voltage
Torque
m
Calculation
Estimator
iA
ą - �
is
iB
ABC
DTC-SVM scheme operated in polar coordinates  ISC
[M.Janecke and F.Hoffman]
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Flux
Controller
�sc
usdc
SA
PI
d - q
usc
SB
SV
M
SC
usqc
mc
ą - �
PI
ł
s
Torque
�s�
sc
Controller
�s
Flux and
Udc
us
Voltage
Torque
m
Calculation
Estimator
iA
ą - �
is
iB
ABC
DTC-SVM scheme operated in Cartesian coordinates - Stator Flux
Oriented Control [U.Bader and X.Xue, X.Xu, T.G.Habetler,
D.M.Divan]
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
1.0
us�
me
0.8
0.6
0.4
is�
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
Response to rated torque reversal of the DTC-SVM scheme
operated in Cartesian coordinates
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
1Layer 5 Layer
2 Layer 3 Layer 4 Layer
Udc
50m s/div
� (1 W b /d iv )
s
w12 o1
min
o2
w22
"łi
is ą (10A/div)
min
w�
w32 o3
Table
min
��
w42 o4
Vsc
min
o5
w52 Vector
m (10N m /div)
e
min
Adder
w62 o6
min �Vc
wm
o7
w72
�m
min
o8
w82
min
o9
w92
łs
min
membership function o5 weight tuning
m (10N m /div)
c
tuning
Neuro-Fuzzy DTC-SVM; a) block scheme, b) experimental
oscillograms illustrating torque-tracking performance
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
Normalization
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
DTC and DTC-SVM
25 us 200 us
No load experimental steady state oscillograms at stator frequency
25Hz. (a) DTC (b) DTC-SVM.
From the top: line to line voltage, phase current, amplitude of stator flux, motor torque.
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
TWERD, Poland
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Experimental Results
Induction Motor PMSM Motor
Steady state operation (ML=0.5MN).
From the top: line to line voltage, line current, stator flux amplitude, electromagnetic torque
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Experimental Results
Induction Motor PMSM Motor
Speed tracking performance (+/-&!mN).
From the top: reference speed, actual speed, electromagnetic torque, line current.
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Experimental Results
Induction Motor PMSM Motor
Transients to step change of load (speed = 750 rpm, ML=0.5MN).
From the top: actual speed, electromagnetic torque, line current.
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
Experimental Results
Induction Motor PMSM Motor
Transients to step change of load (speed = 0 rpm, ML=0.5MN).
From the top: actual speed, electromagnetic torque, line current.
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
CONCLUSIONS
" DTC represents a viable alternative to Field Oriented Control (FOC) being also
a general philosophy for controlling the AC drives in both motor and generator
mode of operation.
" FOC requires an accurate estimation of the rotor flux vector. However, when
an accurate estimation of the motor flux is available, there is no need to set
up a current control loop and DTC is the natural solution.
" The main features of DTC can be summarized as follows:
- DTC operates with closed torque and flux loops without current controllers,
- DTC needs stator flux and torque estimation; is not sensitive to rotor
parameters,
- DTC is inherently a motion sensorless control method,
- DTC has simple and robust control structure; however, the performance of
DTC strongly depends on the quality of the estimation of the actual stator
flux and torque.
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004
WARSAW UNIVERSITY OF TECHNOLOGY
FACULTY OF ELECTRICAL ENGINEERING
Institute of Control and Industrial Electronics
00-662 Warszawa , ul.Koszykowa 75 Tel. (+ 48 22) 628 06 65 , Fax (+ 48 22) 625 66 33
CONCLUSIONS (2)
" Constant switching frequency DTC-SVM schemes improve considerably the
drive performance (reduce torque and flux pulsations, reliable start up and low
speed operation, well-defined harmonic spectrum and radiated noise).
" Short sampling time required by the ST-DTC schemes makes them suited to
very fast torque and flux controlled drives because of the simplicity of the
control algorithm.
" DTC strategy will continue to play a strategic role in the development of high-
performance motion sensorless AC drives
Marian P. Kazmierkowski PELINCEC Seminar, 28 Dec., 2004