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Dynamics Testing of an Industry Oriented Real Time
DTC Induction Motor Drive Using Mat lab Simulink
Brahmananda Das
Department of EE
SpintronicTechnology and Advance Research, Bhubaneswar, Odisha, India
Email-brahman315@gmail
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This is a field oriented control technique in
which the detail analysis of motor parameter are required
as it is very difficult to measure the rotor time constant
which is varies with temperature
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A 149
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2pole cage induction motor of460 volts, 60 Hz,
1800 rpm and inertia constant 10 Kg
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The torque developed was 790 N
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To make a real time model I had
chosen ac source resistance 0
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15mH and model was developed by matlabR2016
simulink environment
...
The inverter used was the
voltage source inverter (VSI) in the sense that this inverter
was fed by a constant DC voltage
...

After simulation I had found that From 0
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25 second, the fan speed increased because of the 600
N
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When time was 0
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When time
was 0
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During
braking mode, power was sent back to the DC bus and the
bus voltage increasesed
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At time is equal to
0
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m and the speed settleed around -10 rpm and reduced
toward 0 rpm
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8 Wb throughout the simulation
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02
and 10 N
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This was due to the combined
effects of the 15 µs DTC controller sampling time, the

hysteresis control, and the switching frequency limitation
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Here torque and flux from stator voltage and current
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1
...

However, Isao Takahashi and Toshihiko Noguchi developed a
similar control technique called as
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The only difference
between DTC and DSC is that the switching frequency of
DTC is higher than DSC and DTC is applicable to low and
medium rated machine drives whereas DSC is usually used for
high rated machine drives
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DTC was then used in electric locomotives
in German aqnd then it is used in ac drives and the applied to
many more applications
...
this is a very simple method
because there is no requirement of pi regulator, coordinate
transformations, current regulators and pwm signals
generators
...
These adaptive intelligent techniques are
applied to achieve high performance decoupled flux and
torque control
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DYNAMIC BRAKING
As the DC bus is provided by a diode rectifier, the drive
doesn't have a bidirectional power flow capability and
therefore cannot perform regenerative braking
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This braking scheme is
called dynamic braking
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With dynamic braking, the kinetic energy
of the motor-load system is converted into heat dissipated in
the braking resistor
...
e
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The hysteresis modulation is a feedback current
control method where the motor current tracks the reference
current within a hysteresis band
...
The
controller generates the sinusoidal reference current of desired
magnitude and frequency that is compared with the actual
motor line current
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As a result, the current
starts to decay
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As a result, the current
gets back into the hysteresis band
...

III
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A logical 1 means that the
upper switch is conducting and logical 0 means that the lower
switch is conducting
...
The space vector modulation technique
differs from the hysteresis modulation in that there are not
separate comparators used for each of the three phases
...
A simplified diagram of a VSI inverter is shown below
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A logical 1 means that the upper switch is conducting and
logical 0 means that the lower switch is conducting
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Hysteresis current controller
IV
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Hysteresis Modulation

...
The space
vector modulation technique differs from the hysteresis
modulation in that there are not separate comparators used for
each of the three phases
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A simplified diagram of
a VSI inverter is shown below
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A logical 1 means that the upper switch is ON and logical
0 means that the lower switch is ON
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The switching states and the corresponding phase to
neutral voltages are summarized in Inverter Space Voltage
Vectors
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The two zero vectors
are at the origin
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The
voltage Vs can be resolved as: Va and Vb are the

(1)

Inverter
Operation

Space
Voltage
Vector

0

1

1

1 Freewheeling

V0

1

1

0

0

Active

V1

2

1

1

0

Active

V2

3

0

1

0

Active

V3

4

0

1

1

Active

V4

5

0

0

1

Active

V5

6

1

0

1

Active

V6

7

0

0

0 Freewheeling

(2)
components of Vs along V1 and V2, respectively
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Flux-Oriented Control:

Table-1 Inverter Space Vector

The construction of a DC machine is such that the field flux is perpendicular
to the armature flux
...
Adjusting the field current can therefore control
the DC machine flux, and the torque can be controlled independently of flux
by adjusting the armature current
...
You can obtain
DC machine-like performance in holding a fixed and orthogonal orientation
between the field and armature fields in an AC machine by orienting the stator
current with respect to the rotor flux so as to attain independently controlled
flux and torque
...
Vector control is applicable to both induction and synchronous
motors
...


The field-oriented control implies that the ids component of the stator
current would be aligned with the rotor field and the iqs component
would be perpendicular to ids
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The electric torque
is proportional to the iqs component, whereas the relation between the flux φr
and the ids component is given by a first-order linear transfer function with a
time constant Lr / Rr
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It can only be estimated from
terminal measurements
...


(13)

(14)

Rotor Flux Position Obtained from the Slip and Rotor
Positions:

4|Page

(21)
The estimated stator flux and electric torque are then
controlled directly by comparing them with their respective
demanded values using hysteresis comparators
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The following table outputs the
appropriate switching state for the inverter
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Direct Torque Control

1
Though the field-oriented control is an attractive control
method but it has a serious drawback that it requires deep
rooted knowledge of the motor parameters and it is difficult to
measure the rotor time constant as it varies with time
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The
following relations are used

-1


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MATLAB SIMULINK MODEL

Fig-6 Entire Model of DTC

VII
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Conclusions
Observe the motor's fast torque response to the torque set
point changes
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02 s to 0
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m acceleration torque produced by the
induction motor
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25 s, the electromagnetic torque
jumps down to 0 Name and the speed decreases because of the
load torque opposed by the fan
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5 s, the motor torque
develops a -600 Name torque and allows braking of the fan
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As planned, the braking chopper
limits the DC bus voltage to 700 V
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75 s, the
electromagnetic torque jumps back to 0 Name and the speed
settles around -10 rpm and decreases toward 0 rpm
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8 Wb throughout the simulation
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02 and 10 Name respectively as specified in the user
interface
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The following figure shows the simulation results of the XY
scope
...
Its modulus is about
0
...
2
...
It allows independent control of
motor stator flux and electromagnetic torque
...
But it introduces undesired torque and current


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Stator voltage space vector
defined in this reference frame control the torque and flux
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In transient state,
by selecting the fastest accelerating voltage vector which
produces maximum slip frequency, highest torque response
can be obtained
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In steady state, the torque can be
maintained constant with small switching frequency by the
torque hysteresis comparator by selecting the accelerating
vector and the zero voltage vector alternately
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In order to
get the optimum efficiency in steady state and the highest
torque response in transient state at the same time, the flux
level can be automatically adjusted
...
If the switching
frequency is extremely low, the control circuit makes some
drift which can be compensated easily to minimize the
machine parameter variation
...

IX
...
, Inc
...
T
...
; Terlizzi, A
...
;
Salvatore, L
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"Comparison Between FOC and
DTC strategies for Permanent Magnet"
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5 (1-2)
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P
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; Rodriguetz, J
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;
Leon, J
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"High Performance Motor Drives"
...
Vol
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3
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6–26
...
1109/mie
...
942173
...
, Manfred
...

[6]Jump
up^ Depenbrock,
November 2012
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Retrieved 13

[7] Jump up^ Noguchi, Toshihiko; Takahashi, Isao (Sep
1984)
...
IEEJ: 61–70
...
"A New Quick-Response and HighEfficiency Control Strategy of an Induction Motor"
...
on Industry Applications: 820–
827
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1109/tia
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4504799
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[9]Jump up^, Gilbert (2010)
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Sydney, Australia: The
University of New South Wales
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Die Direkte-Selbstregelung (DSR) :
e
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Regelung
von
Drehfeldmaschinen (in German) (Als Ms
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ed
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ISBN 3-18-143521-X
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; Kremer, R
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(9–12
Oct 1989)
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Proceedings of the EPE'89
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Torque
Control
(DTC)"
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5 (1):
14–
18
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1109/pedes
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537279
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[14]Jump up^ Nash, J
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(Mar 1997)
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IEEE
Trans
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33 (2):
333–
341
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1109/28
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[15]Jump up^ Harmoinen, Martti; Manninen, Vesa;
Pohjalainen,
Pasi;
Tiitinen,
Pekka
(17
Aug
1999)
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Retrieved 13
November 2012
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(19–21 Sep 1995)
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Proceedings of EPE 95, Sevilla, Spain: 1, 292–
1,296
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; Acarnley, P
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control of permanent magnet drives"
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Retrieved 15 November 2012
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Tammi, Ari (2011)
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ABB Review
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November 2012
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Archived from the original(PDF) on October
18, 2011
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[21]Jump up^ Lascu, C
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; Blaabjerg, F
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"A modified direct torque control (DTC) for induction
motor sensorless drive"
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Louis, MO, USA
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doi:10
...
1998
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[11]Jump up^ "ACS800 - The New All-compatible Drives
Portfolio"
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Jump up^ Lönnberg, M
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(2011)
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ABB Review (2): 63–65
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Direct Torque Control (Repr
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]: Oxford Univ
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ISBN 0198564651
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; Pohjalainen, P
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(May
1995)

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