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

Marian P. Kazmierkowski

Classification of IM control methods

Variable

Frequency

Control

Scalar based

controllers

Vector based

controller

U/f=const

Direct

(Blaschke)

Field Oriented

Direct Torque

Control

Feedback

Linearisation

Indirect

(Hasse)

Circle flux

trajectory

(Takahashi)

Hexagon flux

trajectory

(Depenbrock)

Stator Flux

Oriented

Rotor Flux

Oriented

Direct Torque

Space - Vector

Modulation

Passivity

Based Control

Closed Loop

Flux & Torque

Control

( )

r

s

f

i

ω

=

Open Loop

NFO

(Jonsson)

..

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

Marian P. Kazmierkowski

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.

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

Marian P. Kazmierkowski

Torque production: (a) field-oriented control, (b) direct torque control

M

r

l

l

r

ψ

s

i

δ

sin

e

m

M

r

l

l

Ψ

δ

sin

1

s

l

σ

e

m

s

ψ

r

ψ

(a)

IM

CC-PWM-VSI

α

β

r

ψ

δ

i

s

i

s

(b)

s

u

s

ψ

IM

PWM-VSI

α

β

Ψ

δ

s

ψ

r

ψ

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

Marian P. Kazmierkowski

(a) Simplified diagram of the VS inverter feeding an induction motor; (b)

representation of output voltage vectors

a)

b)

u

1

(100)

u

7

(111)

u

0

(000)

α

β

A

B

C

u

2

(110)

u

3

(010)

u

4

(011)

u

5

(001)

u

6

(101)

U

B

U

dc

1

1

1

0

0

0

U

A

U

C

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

Marian P. Kazmierkowski

Stator flux path in

α-β plane (a) under six-step operation and (b) under

sinusoidal PWM operation (low switching frequency)

a)

b)

α

β

ψ

s

α

β

s

ψ

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

Marian P. Kazmierkowski

Stator flux vector movement relative to rotor flux vector

under the influence of active and zero voltage vectors

stops with zero

vector

moment with active

forward vector

moment with active

backward vector

rotates

continuously

Ψ

δ

s

ψ

r

ψ

d

α

stator

m

H

−

m

H

+

q

sq

e

m

ψ

~

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

Marian P. Kazmierkowski

Two schemes of PWM inverter-fed induction motor with: a) direct

torque and stator flux control (DTC), b) field oriented control (FOC)

a)

b)

u

A

u

B

u

C

Flux

Controller

Active

Vectors

Zero

Vectors

Torque

Controller

Voltage

Vector

Selection

VS

PWM

Inverter

Induction

Motor

S

A

S

B

S

C

c

m

α

s

i

e

m

β

s

i

sc

ψ

s

ψ

Ν(γ

s

)

u

A

u

B

u

C

Coordinate

Transformation

SVM

VS

PWM

Inverter

Induction

Motor

r

γ

S

A

S

B

S

C

q

d

−

β

α −

c

s

U

α

c

s

U

β

q

d

−

β

α −

sin

cos

sq

i

sd

i

α

s

i

e

m

β

s

i

Flux Current

Controller

PI

sdc

i

~

sdc

U

Torque Current

Controller

PI

sqc

c

i

m ~

sqc

U

sc

ψ

s

ψ

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

Marian P. Kazmierkowski

PELINCEC Seminar, 28 Dec., 2004

PEMC ’94: K. Hasse, B.K. Bose, M.P. Kazmierkowski

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

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

Marian P. Kazmierkowski

Sector definition for circular (a) and hexagonal (b) stator flux

vector path

a)

b)

sector 4

sector 1

sector 2

sector 3

sector 5

sector 6

u

1

u

3

u

5

u

7

u

2

u

0

u

6

u

4

α

β

sector 4

sector 1

sector 2

sector 3

sector 5

sector 6

u

1

u

3

u

5

u

7

u

2

u

0

u

6

u

4

α

β

PELINCEC Seminar, 28 Dec., 2004

Marian P. Kazmierkowski

PELINCEC Seminar, 28 Dec., 2004

IECON ’97: P.Z. Grabowski, I. Takahashi, M.P. Kazmierkowski

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

Marian P. Kazmierkowski

Switching Table Based DTC with circular stator flux path according to
Takahashi and Nogouchi (a) block scheme, (b) transient response to

rated torque reversal

a)

b)

s

i

e

m

S

A

S

B

S

C

U

dc

Motor

Torque

Controller

c

m

Flux

Controller

sc

ψ

Ψ

d

m

d

s

u

Voltage

Calculation

Vector

Selection

Table

)

(

s

N

γ

Sector

Detection

Flux and

Torque

estimator

α

ψ

s

β

ψ

s

s

ψ

u

s

β

m

e

i

s

β

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

Marian P. Kazmierkowski

Voltage vectors generated with two (a) and three (b) equal

time intervals per cycle period

a)

b)

sector 1

+

sector 1

-

α

β

sector 4

sector 1

sector 2

sector 3

sector 5

sector 6

u

1

u

3

u

5

u

7

u

2

u

6

u

4

α

β

sector 7

sector 8

sector 9

sector 10

sector 12

sector 12

u

8

u

8

u

9

u

10

u

11

u

12

u

4

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

Marian P. Kazmierkowski

PELINCEC Seminar, 28 Dec., 2004

Bachum ‘96: A.Steimel, M.P. Kazmierkowski, M. Depenbrock

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

Marian P. Kazmierkowski

DSC with hexagonal stator flux path according to Depenbrock (a)

block scheme (b) transient response to rated torque reversal

a)

b)

s

i

U

dc

Motor

Torque

Controller

c

m

Flux

Comparators

s

u

Voltage

Calculation

sc

ψ

e

m

Flux and

Torque

estimator

A B C

α β

B

s

β

ψ

C

s

β

ψ

α

ψ

s

β

ψ

s

A

d

B

d

C

d

s

ψ

∆

ο

d

PI

S

A

S

B

S

C

A

s

β

ψ

u

sβ

m

e

i

sβ

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

Marian P. Kazmierkowski

Operation of the analog (a) and discrete (b) hysteresis controller

m

c

- H

m

t

1

t

2

t

3

S / H

1/Ts

m

c

+ H

m

T

s

T

s

T

s

m

c

(a)

(b)

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

Marian P. Kazmierkowski

DTC-SVM with closed flux control [D. Casadei et.al.]

sc

ψ

r

γ

S

A

S

B

S

C

SVM

s

r

q

d

−

β

α

−

Eqs (16)

c

m

rc

ψ

Stator Flux

Estimator

U

dc

Voltage

Calculation

A

i

B

i

β

α

−

ABC

Rotor Flux

Estimator

s

ψ

s

ψ

∆

sc

u

s

u

s

i

sdc

ψ

sqc

Ψ

S

N

T

T

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

Marian P. Kazmierkowski

DTC-SVM with closed loop torque control [L.Xu, M.Fu]

Torque

Controller

sc

ψ

s

γ

S

A

S

B

S

C

SVM

s

r

PI

Eq. (18)

c

m

sc

ψ

Flux and

Torque

Estimator

U

dc

Voltage

Calculation

A

i

B

i

β

α

−

ABC

s

ψ

sc

u

s

u

s

i

Ψ

δ

∆

m

S

N

T

T

s

ψ

∆

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

Marian P. Kazmierkowski

DTC-SVM scheme operated in polar coordinates – ISC

[M.Janecke and F.Hoffman]

sd

γ

∆

S

A

S

B

S

C

SVM

s

r

Eq. (21)

sc

u

Ψ

k

Flux

Controller

Torque

Controller

c

m

sc

ψ

PI

P

s

γ

∆

Flux and

Torque

Estimator

U

dc

Voltage

Calculation

A

i

B

i

β

α

−

ABC

s

u

s

i

m

s

S

N

T

T

s

ψ

∆

ψ

s

γ

ss

γ

∆

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

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

Marian P. Kazmierkowski

DTC-SVM scheme operated in Cartesian coordinates - Stator Flux

Oriented Control [U.Bader and X.Xue, X.Xu, T.G.Habetler,

D.M.Divan]

S

A

S

B

S

C

SV

M

U

dc

Voltage

Calculation

A

i

B

i

β

α

−

ABC

s

u

s

i

Flux

Controller

Torque

Controller

c

m

sc

ψ

PI

PI

Flux and

Torque

Estimator

q

d

−

β

α

−

m

s

ψ

sc

u

sc

s

ψ

ω

s

γ

sqc

u

sdc

u

PELINCEC Seminar, 28 Dec., 2004

Marian P. Kazmierkowski

Response to rated torque reversal of the DTC-SVM scheme

operated in Cartesian coordinates

0.0

1.0

0.8

0.6

0.4

0.2

-1.0

-0.8

-0.6

-0.4

-0.2

us

β

me

is

β

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

Marian P. Kazmierkowski

Neuro-Fuzzy DTC-SVM; a) block scheme, b) experimental

oscillograms illustrating torque-tracking performance

V

sc

Vector

Adder

min

min

min

min

min

min

Normalization

γ

s

min

min

min

∆γ

i

Table

membership function

tuning

o

5

weight tuning

ε

Ψ

ε

m

U

dc

ϕ

Vc

w

1

2

w

2

2

w

3

2

w

4

2

w

5

2

w

6

2

w

7

2

w

8

2

w

9

2

1Layer

2 Layer

3 Layer 4 Layer

5 Layer

o

1

o

2

o

4

o

8

o

3

o

5

o

6

o

9

o

7

w

Ψ

w

m

Ψ

s

( 1 W b /d iv )

i

s

α

( 1 0 A /d iv )

m

e

( 1 0 N m /d iv )

m

c

( 1 0 N m /d iv )

5 0 m s /d iv

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

Marian P. Kazmierkowski

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.

DTC and DTC-SVM

PELINCEC Seminar, 28 Dec., 2004

25 us

200 us

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

Marian P. Kazmierkowski

PELINCEC Seminar, 28 Dec., 2004

TWERD, Poland

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

Marian P. Kazmierkowski

Steady state operation (M

L

=0.5M

N

).

From the top: line to line voltage, line current, stator flux amplitude, electromagnetic torque

Experimental Results

Induction Motor

PMSM Motor

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

Marian P. Kazmierkowski

Speed tracking performance (+/-

Ω

mN

).

From the top: reference speed, actual speed, electromagnetic torque, line current.

Induction Motor

PMSM Motor

Experimental Results

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

Marian P. Kazmierkowski

Transients to step change of load (speed = 750 rpm, M

L

=0.5M

N

).

From the top: actual speed, electromagnetic torque, line current.

Induction Motor

PMSM Motor

Experimental Results

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

Marian P. Kazmierkowski

Transients to step change of load (speed = 0 rpm, M

L

=0.5M

N

).

From the top: actual speed, electromagnetic torque, line current.

Induction Motor

PMSM Motor

Experimental Results

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

Marian P. Kazmierkowski

PELINCEC Seminar, 28 Dec., 2004

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.

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

Marian P. Kazmierkowski

PELINCEC Seminar, 28 Dec., 2004

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

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