International Journal of Engineering Trends and Technology (IJETT) – Volume 5 Number 7- Nov 2013
Direct Torque Control of Induction Machine Fed by a
Matrix Converter
Gnanavel.C#1, Saranya.P*2 , Saranya.K#3
#
1Assistant Professor, Department of EEE, Vivekananda Institute of Engineering and Technology for
Women, Tiruchengode, Tamil nadu, India.
*2 PG Scholar, Department of EEE, Vivekananda Institute of Engineering and Technology for women,
Tiruchengode, Tamil nadu, India.
#
3 PG Scholar, Department of EEE, Vivekananda Institute of Engineering and Technology for women,
Tiruchengode, Tamil nadu, India.
Abstract—The matrix converter system is competitive solution to
replace the conventional two stage ac to ac converter. In this
paper, a matrix converter driving a speed-controlled induction
machine is examined under open-switch fault. First, a-predictive
direct torque method is proposed using only the motor torque
and current. Second, a motor speed control is presented. The
proposed techniques do not require the additional hardware
devices or circuit modifications to the matrix converter. The
results of this paper show that the proposing method can
maintain the motor speed with a minimum ripple content—a
fivefold improvement over the uncompensated system.
Keywords— reliability, matrix converter, Direct torque control
(DTC), Torque ripple.
I)
INTRODUCTION
Recently, significant research work has been
done in matrix converter (MCs) for control the
induction machines (IMs).The matrix converter
makes the traditional voltage source inverter (VSI)
in ac motor drives using various high-performance
control techniques as direct torque control. The
advantageous features such as bidirectional power
flow, sinusoidal input and out current, input power
factor controllable. There are some critical
applications such as power plants, aerospace,
railway locomotives, automobiles, etc.,
The reasons for installing an input filter before
the matrix converter are twofold: First, it can
mitigate the input current harmonics. Second, it is
used to assist the commutation of switching devices
to assure the normal operation of converter. Since
the first application of matrix converter control, the
space vector modulation (SVM) is mostly used in
three phase DMC control. In this paper, the purpose
of SVM is to trigger pulses for bidirectional IGBT
switches. A direct matrix converter (DMC) is a
ISSN: 2231-5381
single stage converter with m*n bidirectional
switches and this connected to m-phase voltage
source to n-phase load. In practical view, it
connects a three phase source to a three phase load,
typically a motor,
The input filter is mitigates the high frequency
components of the MC input currents, and it almost
generating the sinusoidal sources current, avoiding
the generation of over voltages.
Matrix converter topologies are can be divided
into two types: direct matrix converters (MCs) and
indirect matrix converters (2MCs). Both of these
converters are able to generate input and output
waveforms with same quality. However, in some
applications, the 2MCs may be preferred to direct
matrix converter due to safe commutation switches
and compact circuit and to reducing the number of
power semiconductor switches. A new modulation
and motor control techniques are the direct torque
control (DTC) of induction motors fed matrix
converter.
A matrix converter is a forced commutation direct
frequency converter that can be directly connecting
two independent multiphase voltage system
together (e.g., power grid, alternating current motor
(ac)). And it can be achieve the bidirectional power
flow, independent control of displacement power
factor without use of bulky and limited lifetime
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International Journal of Engineering Trends and Technology (IJETT) – Volume 5 Number 7- Nov 2013
reactive elements, such as large electrolytic
capacitors or ac inductors.
II. GENERAL BLOCK DIAGRAM
A matrix converter (MC) consists of bidirectional
switches, which are directly to connect the power
supply to load without dc link or any storage
element. The matrix converter has several
advantages over traditional rectifier-inverter type
power frequency converters. It provides sinusoidal
input and output waveforms, with minimal higher
order harmonics and no sub harmonics.
Finally, it is particularly sensitive to the
disturbances of the input voltage system.
practical point of view these rules imply that one
and only one bi-directional switch per output phase
must be switched on at any instant. . By this
constraint, in a three phase to three phase matrix
converter 27 are the permitted switching
Combinations.
Fig.2. Circuit scheme of a three phase to three phase matrix converter.
a,b,c are at the input terminals. A, B, C are at the output terminals
B. Scope of this paper
Fig1 .Block diagram for proposed method
A .Topology
The matrix converter consists of 9 bi-directional
switches that allow any output phase to be
connected to any input phase. The circuit scheme is
shown in Fig.2.1.The input terminals of the
converter are connected to a three phase voltage-fed
system, usually the grid, while the output terminal
are connected to a three phase current- fed system,
like an induction motor might be. Regardless to the
control method used, the choice of the matrix
converter switching states combinations (from now
on simply matrix converter configurations) to be
used must comply with two basic rules. From a
ISSN: 2231-5381
This paper seeks to address the aforementioned
problems. A Conventional 3 × 3 matrix converter
driving a speed controlled Induction machine (IM)
is
investigated
both
theoretically
and
experimentally. First, a system description is briefly
presented (Section III). In this proposed, predictive
direct torque control method is used. Finally the
FPGA controller is presented (Section IV). No need
of extra devices is required to maintain balanced
and nearly sinusoidal three-phase output currents.
The experimental results show the proposed method
has satisfactory performance under the operating
condition
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International Journal of Engineering Trends and Technology (IJETT) – Volume 5 Number 7- Nov 2013
III) SYSTEM CONFIGURATION
B. Direct Torque control
A. Configuration Of the Drive System
The proposed drive system of configuration is
shown in Fig. 1. The drive system hardware
consists of a wye-connected Three-phase induction
machine (IM) with mechanical load, a matrix
converter (10-kW rating), and a FPGA system. The
induction machine parameters are listed in Table I.
An encoder (2500 pulses per revolution) is mounted
on the motor shaft.
Direct torque control (DTC) is one method used
in variable
frequency
drives to
control
the torque (and thus finally the speed) of threephase motors. Fig.2 shows the direct torque control
method. Stator flux
linkage is
estimated
by integrating the stator voltages.
The Torque is
estimated as a cross product of estimated stator flux
linkage and measured motor current vector. The
estimated flux magnitude and torque are compared
with their reference values. If the estimated flux or
torque deviates from the reference are more than
allowed tolerance, and the transistors of the variable
frequency drive are turned off and on in such a way
that the flux and torque errors will return in their
tolerant bands as fast as possible. Thus the direct
torque control is one form of the hysteresis or bangbang control.
In matrix converter consists of nine bidirectional
or ac switches, where each of them possesses the
capability of bidirectional energy flow. Each output
phase of a 3 × 3 matrix converter is connected to
three input phases by three ac switches. When one
ac switch of an output phase is an opened fault,
there are two remaining ac switches that can be
used to connect to the two related input phases. The
two remaining healthy output phases can still
The properties of DTC can be characterized as
receive any of the possible voltage from the three
input phases. This scenario is different from an follows:
open-circuit fault introduced by the load. All three
 Torque and flux are can be changed very
ac switches connected to the faulty output phase
fast by changing the references.
become useless, reforming a 3 × 2 hardware matrix
 High efficiency & low losses - switching
with floating load neutral point. Previously
losses are minimized because the transistors
discussed approaches usually employ some
are switched only when it is needed to keep
supporting redundant devices to either perform the
torque and flux within their hysteresis bands.
following: 1) connect the opened phase to some
 The step response has no overshoot.
redundant leg or 2) connect the load neutral point to
some rational reference point [22], [24], [26].In this
paper, predictive direct torque control method is
for control the speed and torque. This predictive
direct torque control method is directly to control
the torque. Direct torque control (DTC) is one
method used in variable frequency drives to control
the torque (and thus finally the speed) of threephase motors. This involves calculating an estimate
of the motor's magnetic flux and torque based on
the measured voltage and current of the motor. In
the recent years, the predictive direct control
techniques are emerging as a promising control
solution for high power AC induction
Machine drives. For that reason, this project adopts
the predictive direct control theory, and to
Develop the several new and competitive control
methods for the doubly fed induction machine.
Fig.2.1 Block diagram For Direct torque control.
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 5 Number 7- Nov 2013




No coordinate transforms are needed, and
all calculations are done in stationary
coordinate system.
No separate modulator is needed, and the
hysteresis control defines the switch control
signals are directly.
There are no current controllers. Thus there
are no tuning of the control is required.
The switching frequency of the transistors is
not constant. However, by controlling the width
of the tolerance bands and the average of
switching frequency can be kept roughly at its
reference value. This is also keeps the current
with vector controlled drives with the same
switching frequency.




Comparison
property
Dynamic response to
torque
DTC
Very fast
FOC
Fast

Coordinates reference
alpha, beta (stator)
frame
d, q (rotor)
Low speed (< 5% of
nominal) behaviour
Good with
position or
speed
sensor
Controlled variables
Requires speed sensor for
continuous braking
torque & stator flux
rotor flux,
torque
current iq
& rotor
flux
current id
vector
component
s


Due to the hysteresis control the switching
process is random by nature.
Voltage ripple (aliasing) or dc voltage
transients.
Synchronization to rotating machine is
straightforward due to the fast control; Just
make the torque reference zero and start the
inverter.
Digital control equipment has to be very
fast in order to be able to prevent the flux and
torque from deviating far from the tolerance
bands. Typically the control algorithm has to
be performed within 10 - 30 microseconds or
shorter intervals. However, the amount of
calculations are required small due to the
simplicity of the algorithm.
The current measuring devices have to be
high quality ones without noise because spikes
in the measured signals easily cause erroneous
control actions. Further complication is that
no low-pass filtering can be used to remove
noise because filtering causes delays in the
resulting actual values that ruins the hysteresis
control.
In higher speeds the method is not sensitive
to any motor parameters.
The stator voltage measurements should
have as low offset error as possible in order to
keep the flux estimation error down. For this
reason the stator voltages are usually estimated
from the measured DC intermediate circuit
voltage and the transistor control signals

Stator flux estimation becomes critical.
IV) RESULT AND DISCUSSION
Steady-state
torque/current/flux
ripple & distortion
Low (requires high quality
current sensors)
Low
and torque ripple in small. Thus the torque and
current ripple are of the same magnitude than
ISSN: 2231-5381
Direct torque control method is implemented
in matrix converter using PI controller. The matrix
converter output has shown in fig. Below,
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International Journal of Engineering Trends and Technology (IJETT) – Volume 5 Number 7- Nov 2013
a)Input supply graph is shown in fig.
d) voltage and current
b) Matrix converter current
ii) speed control
c) voltage
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iii) torque control
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International Journal of Engineering Trends and Technology (IJETT) – Volume 5 Number 7- Nov 2013
THE SIMULATION CIRCUIT
V) CONCLUSION
This paper presents a speed control of matrix
converter fed by an induction machine. By using
this matrix converter, sinusoidal input and output
waveform is obtained, with minimal higher order
harmonics and no sub-harmonics. In this induction
machine, the squirrel cage induction machine is
used. In my feature work, FPGA controller is
implemented and to control the torque of matrix
converter. In this paper discussed about only the
torque control of matrix converter using PI
controller.
REFERENCES
[1] A. Alesina and M. Venturini, “Analysis and design of
optimum-amplitude nine-switch direct ac–ac converters,”
IEEE Trans. Power Electron., vol. 4, no. 1, pp. 101–112, Jan.
1989.
[2] J.-H. Youm and B.-H. Kwon, “Switching technique for
current-controlled AC-to-AC converters,” IEEE Trans. Ind.
Electron., vol. 46, no. 2, pp. 309–318, Apr. 1999.
[3] J. Mahlein, J. Igney, J. Weigold, M. Braun, and O. Simon,
“Matrix converter commutation strategies with and without
explicit input voltage sign measurement,” IEEE Trans. Ind.
Electron., vol. 49, no. 2, pp. 407–414, Apr. 2002.
[4] R. Teichmann and J. Oyama, “ARCP soft-switching
technique in matrix converters,” IEEE Trans. Ind. Electron.,
vol. 49, no. 2, pp. 353–361, Apr. 2002.
[5] F. Bradaschia, M. C. Cavalcanti, F. A. S. Neves, and H. E.
P. de Souza, “A modulation technique to reduce switching
losses in matrix converters,” IEEE Trans. Ind. Electron., vol.
56, no. 4, pp. 1186–1195, Apr. 2009.
ISSN: 2231-5381
[6] D.-F. Chen and T.-H. Liu, “Optimal controller design for a
matrix converter based surface mounted PMSM drive
system,” IEEE Trans. Power Electron., vol. 18, no. 4, pp.
1034–1046, Jul. 2003.
[7] T.-H. Liu, S.-H. Chen, and D.-F. Chen, “Design and
implementation of a matrix converter PMSM drive without a
shaft sensor,” IEEE Trans. Aerosp. Electron. Syst., vol. 39, no.
1, pp. 228–243, Jan. 2003.
[8] D.-F. Chen and T.-H. Liu, “Implementation of a novel
matrix converter PMSM drive,” IEEE Trans. Aerosp. Electron.
Syst., vol. 37, no. 3, pp. 863–875, Jul. 2001.
[9] M. Y. Lee, P. Wheeler, and C. Klumpner, “Space-vector
modulated multilevel matrix converter,” IEEE Trans. Ind.
Electron., vol. 57, no. 10, pp. 3385–3394, Oct. 2010.
[10] H. Nguyen, H.-H. Lee, and T.-W. Chun, “Input power
factor compensation algorithms using a new direct-SVM
method for matrix converter,” IEEE Trans. Ind. Electron., vol.
58, no. 1, pp. 232–243, Jan. 2011.
[11] K. S. Smith, L. Ran, and J. Penman, “Real-time detection
of intermittent misfiring in a voltage-fed PWM inverter
induction-motor drive,” IEEE Trans. Ind. Electron., vol. 44,
no. 4, pp. 468–476, Aug. 1997.
[12] V. John, B.-S. Suh, and T. A. Lipo, “Fast-clamped shortcircuit protection of IGBT’s,” IEEE Trans. Ind. Appl., vol. 35,
no. 2, pp. 477–486, Mar./Apr. 1999.
[13] M. Rodriguez, A. Claudio, D. Theilliol, and L. Velan, “A
new fault detection technique for IGBT based on gate voltage
monitoring,” in Proc. IEEE Power Electron. Spec. Conf., Jun.
2007, pp. 1001–1005.
[14] F. Huang and F. Flett, “IGBT fault protection based on
di/dt feedback control,” in Proc. IEEE Power Electron. Spec.
Conf., Jun. 2007, pp. 1478– 1484.
[15] A. M. S. Mendes and A. J. M. Cardoso, “Voltage source
inverter fault diagnosis in variable speed ac drives, by the
average current Park’s vector approach,” in Proc. IEEE
IEMDC, May 1999, pp. 704–706.
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