1 ijaems oct-2015-3-design and development of novel matrix converter performance
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The document discusses the design and development of a novel matrix converter technique aimed at improving performance in induction motor drives. It highlights an indirect space vector modulation scheme that enhances stability under various input conditions and presents experimental results validating the performance of a developed laboratory prototype. The paper includes insights into the advantages of matrix converters over traditional AC-DC-AC converters, emphasizing their efficiency and versatility in power conversion applications.
![International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015]
ISSN : 2454-1311
www.ijaems.com Page | 1
Design and Development of Novel Matrix
Converter Performance Enhancement
Technique for Induction Motor Drive
Suriti Gupta1
, K.C. Roy2
, Vinod Kumar3
, Navneet Agrawal4
1
Pacific University of Higher Education and Research University, Udaipur, Rajasthan, India.
2
Madhav University, Abu Road, Sirohi, Rajasthan, India.
3,4
College of Technology and Engineering, Udaipur, Rajasthan, India.
Abstract—Matrix converter is a direct AC-AC converter
topology that directly converts energy from an AC source
to an AC load without the need of a bulky and limited
lifetime energy storage element. Due to the significant
advantages offered by matrix converter, such as
adjustable power factor, capability of regeneration and
high quality sinusoidal input/output waveforms. Matrix
converter has been one of the AC–AC topologies that
hasreceived extensive research attention for being an
alternative to replace traditional AC-DC-AC converters
in the variable voltage and variable frequency AC drive
applications. In the present paper an indirect space
vector modulated matrix converter is proposed. The basic
idea of an indirect modulation scheme is to separately
apply SVM to the rectification and inversion stages,
before combining their switching states to produce the
final gating signals. The paper encompasses development
of a laboratory prototype of 230V, 250VA three phase to
three phase DSP controlled matrix converter fed
induction motor drive. The observations and real time
testings have been carried out to evaluate and improve
the stability of system under various typical abnormal
input voltage conditions
Keywords—Fuzzy Image Fusion, Image Enhancement,
Image Sharpening,Magnitude Gradient, Standard
Deviation.
I. INTRODUCTION
AC/AC converters take power from an AC system and
deliver it to another with waveforms of adjustable
amplitudes and frequencies. In direct AC/AC converters,
the cyclo-converter is the most commonly employed
topology in three-phase to three-phase applications,
making use of semiconductor switches to connect
directly the power supply to the load, converting a three-
phase AC voltage to a three-phase AC voltage with
adjustable magnitude and variable frequency. It allows
power flow in either direction. The operating output
frequency of this direct converter should be less than the
input frequency. In addition to the cyclo-converters,
matrix converters have enjoyed increasing interest as
direct converters in recent years.
Most of the converters use diode-rectifiers (followed by a
DC-link capacitor), which draw non-sinusoidal currents
(iA, iB, iC) even when fed with a balanced sinusoidal
voltages (VA, VB, VC). Only considering the load side
currents (ia, ib, ic), the diode rectifier based VSI may be a
good solution, but its side currents (iA, iB, iC) are highly
distorted, containing high amounts of low order
harmonics which may further interfere with the other
electric systems in the network. In addition, the current
flow on diodes cannot be reversed. Thus, bi-directional
power flow cannot be provided without using an auxiliary
circuit.
A conventional solution for the harmonics in input current
waveforms and bi-directional power flow problems is to
use a controlled bridge rectifier i.e. back-to-back voltage
source converter (BBVSC) instead of diode rectifier as
shown in Fig. 1. The BBVSC draws sinusoidal current
waveforms (iA, iB, iC) from the AC supply. It contains a
DC-link capacitor between controlled bridge rectifier and
the inverter bridge and supply filter inductors.
Fig. 1: Fuzzy inference system
The arrangement has limitation of bulkier and heavy
supply filter inductors (Ls) andDC-link capacitorin low
and medium power conversion.
II. MATRIX CONVERTERS
Cyclo-converter cannot be seen as an optimal solution for
low and medium power level converters because of
restricted output frequencies and poor harmonic
performance. However, for the high power levels, cyclo-](https://image.slidesharecdn.com/1ijaems-oct-2015-3-designanddevelopmentofnovelmatrixconverterperformance-151013084721-lva1-app6891/85/1-ijaems-oct-2015-3-design-and-development-of-novel-matrix-converter-performance-1-320.jpg)
![International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015]
ISSN : 2454-1311
www.ijaems.com Page | 2
converter can be seen as an optimal solution due to the
low loses and robustness. Matrix convertor is much
versatile without imposing any limits on the operating
output frequencies. It performs direct AC/AC power
conversion process from AC utility to AC load, with
neither intermediate DC conversion nor DC energy
storage elements. Thus, it replaces the multiple
conversion stages by a single power conversion stage. By
the way, the converter size and volume can be greatly
reduced compared to the indirect AC/AC power
converters which have DC-link components. Thus, direct
converter topologies may provide a solution for
application where large passive components are not
allowed.
Fig. 2: Indirect Matrix Converter
Due to the independence of the voltage form and
frequency on the input and output sides, the matrix
convertor topology holds a promising potential for
universal power conversion such as: ac-dc, dc-ac, dc-dc
and ac-ac (Mohan et al. 2003).
The real development of the matrix converter starts with
the work of Venturini and Alesina who proposed a
mathematical analysis and introduced the Low-Frequency
Modulation Matrix concept to describe the low frequency
behavior of the matrix converter. In this, the output
voltages are obtained by multiplication of the modulation
matrix or transfer matrix with the input voltages.
III. METHODOLOGY
The proposed work mainly focuses on an indirect space
vector modulation. The main idea of the indirect
modulation is to consider the matrix converter as a two-
stage transformation converter. This separation allows
known PWM strategies to be implemented in both the
rectifier and the inverter stage. During each sampling
interval, DSP will first start the on board A/D converter to
sample the input three phase voltages, then make them
through comparators to determine the sector code of the
input voltage vector. According to the displacement angle
set, the switching table is formulated. At last, DSP
converts the switching times data to switching pulses, and
then sends the sector codes to the PLD (Programmable
Logic Device) board. In DSP, the duty cycles of the five
switching combinations are calculated and PWM pulses
are generated. PLD will deliver the pulses to the
appropriate bidirectional switches and fulfil the four-
stepped commutation.Block diagram of the proposed DSP
controller based matrix converter for induction motor
control is shown in figure 3.
Fig. 3: Flowchart of proposed approach
Modulation synthesize the output voltages from the input
voltages and the input currents from the output currents.
The first modulator proposed for Matrix Converters,
known as the Venturini modulation, employed a scalar
model. This model gives a maximum voltage transfer
ratio of 0.5. An injection of a third harmonic of the input
and output voltage was proposed in order to fit the
reference output voltage in the input system envelope.
This technique is used to achieve a voltage transfer ratio
with a maximum value of 0.866. The three phase matrix
converter can be represented by a 3 by 3 matrix form
because the nine bidirectional switches can connect one
input phase to one output phase directly without any
intermediate energy storage elements. Both power stages
are directly connected through virtual dc-link and
inherently provide bidirectional power flow capability
because of its symmetrical topology.
IV. DSP-BASED SVM ALGORITHM
IMPLEMENTATION
The general requirements for generating the switch
control signals for a matrix converter on-line in real-time
are as follows:
i). Computation of the switch duty cycles must be
completed within one switching period.
ii). Accurate timing of the pulse-pattern output should
be achieved, and
iii). The computational process must be synchronized
with the input-voltage sinusoidal cycle.
For both modulation methods, a TMS320F30
digital signal processor was used for on-line calculation
of the switch timings. The DSP is mounted on A PC-
compatible card, the Evaluation Module (EVM) to
facilitate the development process . An additional
interface card was used for outputting the calculated](https://image.slidesharecdn.com/1ijaems-oct-2015-3-designanddevelopmentofnovelmatrixconverterperformance-151013084721-lva1-app6891/85/1-ijaems-oct-2015-3-design-and-development-of-novel-matrix-converter-performance-2-320.jpg)
![International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015]
ISSN : 2454-1311
www.ijaems.com Page | 2
converter can be seen as an optimal solution due to the
low loses and robustness. Matrix convertor is much
versatile without imposing any limits on the operating
output frequencies. It performs direct AC/AC power
conversion process from AC utility to AC load, with
neither intermediate DC conversion nor DC energy
storage elements. Thus, it replaces the multiple
conversion stages by a single power conversion stage. By
the way, the converter size and volume can be greatly
reduced compared to the indirect AC/AC power
converters which have DC-link components. Thus, direct
converter topologies may provide a solution for
application where large passive components are not
allowed.
Fig. 2: Indirect Matrix Converter
Due to the independence of the voltage form and
frequency on the input and output sides, the matrix
convertor topology holds a promising potential for
universal power conversion such as: ac-dc, dc-ac, dc-dc
and ac-ac (Mohan et al. 2003).
The real development of the matrix converter starts with
the work of Venturini and Alesina who proposed a
mathematical analysis and introduced the Low-Frequency
Modulation Matrix concept to describe the low frequency
behavior of the matrix converter. In this, the output
voltages are obtained by multiplication of the modulation
matrix or transfer matrix with the input voltages.
III. METHODOLOGY
The proposed work mainly focuses on an indirect space
vector modulation. The main idea of the indirect
modulation is to consider the matrix converter as a two-
stage transformation converter. This separation allows
known PWM strategies to be implemented in both the
rectifier and the inverter stage. During each sampling
interval, DSP will first start the on board A/D converter to
sample the input three phase voltages, then make them
through comparators to determine the sector code of the
input voltage vector. According to the displacement angle
set, the switching table is formulated. At last, DSP
converts the switching times data to switching pulses, and
then sends the sector codes to the PLD (Programmable
Logic Device) board. In DSP, the duty cycles of the five
switching combinations are calculated and PWM pulses
are generated. PLD will deliver the pulses to the
appropriate bidirectional switches and fulfil the four-
stepped commutation.Block diagram of the proposed DSP
controller based matrix converter for induction motor
control is shown in figure 3.
Fig. 3: Flowchart of proposed approach
Modulation synthesize the output voltages from the input
voltages and the input currents from the output currents.
The first modulator proposed for Matrix Converters,
known as the Venturini modulation, employed a scalar
model. This model gives a maximum voltage transfer
ratio of 0.5. An injection of a third harmonic of the input
and output voltage was proposed in order to fit the
reference output voltage in the input system envelope.
This technique is used to achieve a voltage transfer ratio
with a maximum value of 0.866. The three phase matrix
converter can be represented by a 3 by 3 matrix form
because the nine bidirectional switches can connect one
input phase to one output phase directly without any
intermediate energy storage elements. Both power stages
are directly connected through virtual dc-link and
inherently provide bidirectional power flow capability
because of its symmetrical topology.
IV. DSP-BASED SVM ALGORITHM
IMPLEMENTATION
The general requirements for generating the switch
control signals for a matrix converter on-line in real-time
are as follows:
i). Computation of the switch duty cycles must be
completed within one switching period.
ii). Accurate timing of the pulse-pattern output should
be achieved, and
iii). The computational process must be synchronized
with the input-voltage sinusoidal cycle.
For both modulation methods, a TMS320F30
digital signal processor was used for on-line calculation
of the switch timings. The DSP is mounted on A PC-
compatible card, the Evaluation Module (EVM) to
facilitate the development process . An additional
interface card was used for outputting the calculated](https://image.slidesharecdn.com/1ijaems-oct-2015-3-designanddevelopmentofnovelmatrixconverterperformance-151013084721-lva1-app6891/85/1-ijaems-oct-2015-3-design-and-development-of-novel-matrix-converter-performance-3-320.jpg)
![International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015]
ISSN : 2454-1311
www.ijaems.com Page | 4
the same as the input L-C filter, which gives some
freedom to the user to change the parameters and
configuration for the passive components. For evaluating
the performance of the algorithm of proposed method
following parameters are used.
4.1 Experimental Setup
The complete simulationmodel for induction motor fed
by a three phase matrix converter through an indirect
space vector modulation approach is shown in figure 4.
Fig. 4: SVM Based simulation model for induction
motor fed by a three phase matrix converter
The MC is used to drive a standard induction motor
having the following parameters shown in table 1.
Table 1: Motor Parameters
Voltage 400 V
Nominal Power 4 Kw
Frequency 50Hz
Pole Pair
2
Torque
20
Rotation Inertia . 0.0131 Kg·m²
Stator Resistance (Rs) 0.3578Ω
Rotor Resistance (R’r) 0.2861Ω
Stator Inductance (Ls) 0.03972H
Rotor Resistance (L’r) 0.03972H
Mutual Inductance (Lm) 0.03841H
The simulations have been carried out assuming a
sampling frequency of 2μs and ideal switching devices.
The dynamic behavior of the system has been tested with
reference to a load step change response and impact speed
response. Some simulation studies have been done using
system parameters in Table 2.
Table 2: Input Parameters
Source voltage amplitude, Vin 220 V
Input frequency, fi 50 Hz
Input filter inductance, Lf 3 mH
Input filter capacitance, Cf 25 μF
Switching frequency, fs 6 kHz
The results found using MATLAB/SIMULINK are
validated by performing experiments on available
laboratory kit and are shown in the following section. The
experimental setup of matrix converter prototype and the
main circuit as well as power-control-isolation module of
prototype with measuring instruments are shown in
Figure 5.
Fig. 5: Experimental set-up of the matrix
converter drive system
For this, a 230V, 250VA three phase to three phase MC
fed induction motor drive prototype is implemented using
DSP based controller and tests have been carried out to
evaluate and improve the stability of system under
various typical abnormal input voltage conditions. Digital
storage oscilloscope & power quality analyzer are used
for experimental observations. For the purpose of
generating various AC voltages, an AC source
equipment-Elgar SW5253A is used which generates three
phase output voltages with various amplitudes, various
frequency and various waveforms. The equivalent circuit
parameters of the test motor are obtained through light
running and blocked rotor tests. Effect of saturation on
magnetizing reactance has been found from zero slip
tests.](https://image.slidesharecdn.com/1ijaems-oct-2015-3-designanddevelopmentofnovelmatrixconverterperformance-151013084721-lva1-app6891/85/1-ijaems-oct-2015-3-design-and-development-of-novel-matrix-converter-performance-4-320.jpg)
![International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015]
ISSN : 2454-1311
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V. RESULTS AND DISCUSSION
Performance of Matrix Converter fed induction motor
drive under abnormal input frequency and voltage
conditions of power supply is analyzed. These abnormal
conditions of input power supply have a great influence
on the input/output performance of induction drive. Fig.
shows motor performance curves due to drop in supply
frequency from 50 to 30 Hz for 1 sec. Sudden drop in
frequency cause drop in speed of motor and reaches
steady state speed at 0.95 secs shown in figure 6.
Time(sec)
(a)
Time(sec)
(b)
(c)
(d)
Fig. 6 (a) Speed and load Torque Response (b) Stator and
Rotor Current (c) Input Current (d) Output Current at
Abnormal input supply
The high performance matrix converter gives a very rapid
response to sudden input frequency drop for few seconds.
The rapid recovery of the stator and rotor current to this
dynamic event is also clearly shown in figure 6(b). It first
oscillates with the rapidly varying current before
achieving steady-state. The speed of recovery is
extremely fast, as stability is reached within few
switching cycles.After evaluating the performance of the
system under 20% step change in frequency using
Simulink, it is validated by the experimental results.It is
observed that the obtained experimental results are similar
to the simulation results.
5.1 Results under Abnormal Input Voltage Conditions
Fig. 7 and 8 show the input/ output current & voltages,
when system is operated with unbalanced power supply.
The rms values of the input three-phase voltages are
72.6V, 109.8V and 128.2V respectively.
Time(sec)
OutputCurrent(A)
Rotorcurrent(A)Statorcurrent(A)
Torque(Nm)Speed(rad/sec)
InputCurrent(A)
Time(sec)
Time(sec)](https://image.slidesharecdn.com/1ijaems-oct-2015-3-designanddevelopmentofnovelmatrixconverterperformance-151013084721-lva1-app6891/85/1-ijaems-oct-2015-3-design-and-development-of-novel-matrix-converter-performance-5-320.jpg)
![International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015]
ISSN : 2454-1311
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Fig. 7: Input & Output phase voltage at 30 Hz.
Fig. 8: Output line current at 30 Hz.
Fig. 9: Output line voltage.
AC source provides 450mS of blackout of the three phase
voltages. Fig.9 shows the matrix converter output line
voltage. It demonstrate rapid re-starting capability of
matrix converter indicating that during the power
interruption the power delivered to load is interrupted ,
however, following the line voltage restoration, the matrix
converter rapidly resumes operation and delivers power
quickly as compared to PWM converters.
VI. CONCLUSION
Modeling of the system is developed including modeling
of induction motor and DSP controlled matrix converter
structure.The paper presented indirect space vector
modulation technique for three phase-to-three phase
matrix converter. The resulting expressions of the
modulation signals are simple and suitable for practical
implementation. Besides, it is general that it can be used
for unbalanced input voltages.
REFERENCES
[1] Venugopal, C., "Fuzzy logic based DTC for speed
control of Matrix Converter fed Induction Motor,"
Power and Energy (PECon), 2010 IEEE
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Nov. 29 2010-Dec. 1 2010.
[2] Correa, P.; Rodriguez, J.; Rivera, M.; Espinoza, J.R.;
Kolar, J.W., "Predictive Control of an Indirect Matrix
Converter," Industrial Electronics, IEEE
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2009
[3] Kumar, V.; Joshi, R. R., "DSP-Based Matrix
Converter Operation Under Various Abnormal
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Drives and Energy Systems, 2006. PEDES '06.
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Dec. 2006.
[4] Vargas, R.; Ammann, U.; Rodriguez, J.; Pontt, J.,
"Predictive Strategy to Control Common-Mode
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[5] Wheeler, P.W.; Clare, J.C.; Apap, M.; Bradley, K.J.,
"Harmonic Loss Due to Operation of Induction
Machines From Matrix Converters," Industrial
Electronics, IEEE Transactions on , vol.55, no.2,
pp.809,816, Feb. 2008
[6] Faraji, V.; Aghasi, M.; Khaburi, D.A.; Ghorbani,
M.J., "A modified DTC for induction motor drive
system fed by Indirect Matrix Converter using Active
Learning Method," Power Electronics, Drive Systems
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[7] Reusser, C.A.; Silva, C.A.; Dominguez, P., "Low
frequency sensorless Field Oriented Control of an
induction machine fed by a direct matrix converter,"
Industrial Electronics Society, IECON 2013 - 39th
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[8] Lopez, M.; Rivera, M.; Garcia, C.; Rodriguez, J.;
Pena, R.; Espinoza, J.; Wheeler, P., "Predictive
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[9] Metidji, B.; Taib, N.; Baghli, L.; Rekioua, T.; Bacha,
S., "Novel Single Current Sensor Topology for
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www.ijaems.com Page | 7
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[14] Wang X., Lin H., She H. and Feng B., Jan. 2012 “A
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1 ijaems oct-2015-3-design and development of novel matrix converter performance
- 1. International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015] ISSN : 2454-1311 www.ijaems.com Page | 1 Design and Development of Novel Matrix Converter Performance Enhancement Technique for Induction Motor Drive Suriti Gupta1 , K.C. Roy2 , Vinod Kumar3 , Navneet Agrawal4 1 Pacific University of Higher Education and Research University, Udaipur, Rajasthan, India. 2 Madhav University, Abu Road, Sirohi, Rajasthan, India. 3,4 College of Technology and Engineering, Udaipur, Rajasthan, India. Abstract—Matrix converter is a direct AC-AC converter topology that directly converts energy from an AC source to an AC load without the need of a bulky and limited lifetime energy storage element. Due to the significant advantages offered by matrix converter, such as adjustable power factor, capability of regeneration and high quality sinusoidal input/output waveforms. Matrix converter has been one of the AC–AC topologies that hasreceived extensive research attention for being an alternative to replace traditional AC-DC-AC converters in the variable voltage and variable frequency AC drive applications. In the present paper an indirect space vector modulated matrix converter is proposed. The basic idea of an indirect modulation scheme is to separately apply SVM to the rectification and inversion stages, before combining their switching states to produce the final gating signals. The paper encompasses development of a laboratory prototype of 230V, 250VA three phase to three phase DSP controlled matrix converter fed induction motor drive. The observations and real time testings have been carried out to evaluate and improve the stability of system under various typical abnormal input voltage conditions Keywords—Fuzzy Image Fusion, Image Enhancement, Image Sharpening,Magnitude Gradient, Standard Deviation. I. INTRODUCTION AC/AC converters take power from an AC system and deliver it to another with waveforms of adjustable amplitudes and frequencies. In direct AC/AC converters, the cyclo-converter is the most commonly employed topology in three-phase to three-phase applications, making use of semiconductor switches to connect directly the power supply to the load, converting a three- phase AC voltage to a three-phase AC voltage with adjustable magnitude and variable frequency. It allows power flow in either direction. The operating output frequency of this direct converter should be less than the input frequency. In addition to the cyclo-converters, matrix converters have enjoyed increasing interest as direct converters in recent years. Most of the converters use diode-rectifiers (followed by a DC-link capacitor), which draw non-sinusoidal currents (iA, iB, iC) even when fed with a balanced sinusoidal voltages (VA, VB, VC). Only considering the load side currents (ia, ib, ic), the diode rectifier based VSI may be a good solution, but its side currents (iA, iB, iC) are highly distorted, containing high amounts of low order harmonics which may further interfere with the other electric systems in the network. In addition, the current flow on diodes cannot be reversed. Thus, bi-directional power flow cannot be provided without using an auxiliary circuit. A conventional solution for the harmonics in input current waveforms and bi-directional power flow problems is to use a controlled bridge rectifier i.e. back-to-back voltage source converter (BBVSC) instead of diode rectifier as shown in Fig. 1. The BBVSC draws sinusoidal current waveforms (iA, iB, iC) from the AC supply. It contains a DC-link capacitor between controlled bridge rectifier and the inverter bridge and supply filter inductors. Fig. 1: Fuzzy inference system The arrangement has limitation of bulkier and heavy supply filter inductors (Ls) andDC-link capacitorin low and medium power conversion. II. MATRIX CONVERTERS Cyclo-converter cannot be seen as an optimal solution for low and medium power level converters because of restricted output frequencies and poor harmonic performance. However, for the high power levels, cyclo-
- 2. International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015] ISSN : 2454-1311 www.ijaems.com Page | 2 converter can be seen as an optimal solution due to the low loses and robustness. Matrix convertor is much versatile without imposing any limits on the operating output frequencies. It performs direct AC/AC power conversion process from AC utility to AC load, with neither intermediate DC conversion nor DC energy storage elements. Thus, it replaces the multiple conversion stages by a single power conversion stage. By the way, the converter size and volume can be greatly reduced compared to the indirect AC/AC power converters which have DC-link components. Thus, direct converter topologies may provide a solution for application where large passive components are not allowed. Fig. 2: Indirect Matrix Converter Due to the independence of the voltage form and frequency on the input and output sides, the matrix convertor topology holds a promising potential for universal power conversion such as: ac-dc, dc-ac, dc-dc and ac-ac (Mohan et al. 2003). The real development of the matrix converter starts with the work of Venturini and Alesina who proposed a mathematical analysis and introduced the Low-Frequency Modulation Matrix concept to describe the low frequency behavior of the matrix converter. In this, the output voltages are obtained by multiplication of the modulation matrix or transfer matrix with the input voltages. III. METHODOLOGY The proposed work mainly focuses on an indirect space vector modulation. The main idea of the indirect modulation is to consider the matrix converter as a two- stage transformation converter. This separation allows known PWM strategies to be implemented in both the rectifier and the inverter stage. During each sampling interval, DSP will first start the on board A/D converter to sample the input three phase voltages, then make them through comparators to determine the sector code of the input voltage vector. According to the displacement angle set, the switching table is formulated. At last, DSP converts the switching times data to switching pulses, and then sends the sector codes to the PLD (Programmable Logic Device) board. In DSP, the duty cycles of the five switching combinations are calculated and PWM pulses are generated. PLD will deliver the pulses to the appropriate bidirectional switches and fulfil the four- stepped commutation.Block diagram of the proposed DSP controller based matrix converter for induction motor control is shown in figure 3. Fig. 3: Flowchart of proposed approach Modulation synthesize the output voltages from the input voltages and the input currents from the output currents. The first modulator proposed for Matrix Converters, known as the Venturini modulation, employed a scalar model. This model gives a maximum voltage transfer ratio of 0.5. An injection of a third harmonic of the input and output voltage was proposed in order to fit the reference output voltage in the input system envelope. This technique is used to achieve a voltage transfer ratio with a maximum value of 0.866. The three phase matrix converter can be represented by a 3 by 3 matrix form because the nine bidirectional switches can connect one input phase to one output phase directly without any intermediate energy storage elements. Both power stages are directly connected through virtual dc-link and inherently provide bidirectional power flow capability because of its symmetrical topology. IV. DSP-BASED SVM ALGORITHM IMPLEMENTATION The general requirements for generating the switch control signals for a matrix converter on-line in real-time are as follows: i). Computation of the switch duty cycles must be completed within one switching period. ii). Accurate timing of the pulse-pattern output should be achieved, and iii). The computational process must be synchronized with the input-voltage sinusoidal cycle. For both modulation methods, a TMS320F30 digital signal processor was used for on-line calculation of the switch timings. The DSP is mounted on A PC- compatible card, the Evaluation Module (EVM) to facilitate the development process . An additional interface card was used for outputting the calculated
- 3. International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015] ISSN : 2454-1311 www.ijaems.com Page | 2 converter can be seen as an optimal solution due to the low loses and robustness. Matrix convertor is much versatile without imposing any limits on the operating output frequencies. It performs direct AC/AC power conversion process from AC utility to AC load, with neither intermediate DC conversion nor DC energy storage elements. Thus, it replaces the multiple conversion stages by a single power conversion stage. By the way, the converter size and volume can be greatly reduced compared to the indirect AC/AC power converters which have DC-link components. Thus, direct converter topologies may provide a solution for application where large passive components are not allowed. Fig. 2: Indirect Matrix Converter Due to the independence of the voltage form and frequency on the input and output sides, the matrix convertor topology holds a promising potential for universal power conversion such as: ac-dc, dc-ac, dc-dc and ac-ac (Mohan et al. 2003). The real development of the matrix converter starts with the work of Venturini and Alesina who proposed a mathematical analysis and introduced the Low-Frequency Modulation Matrix concept to describe the low frequency behavior of the matrix converter. In this, the output voltages are obtained by multiplication of the modulation matrix or transfer matrix with the input voltages. III. METHODOLOGY The proposed work mainly focuses on an indirect space vector modulation. The main idea of the indirect modulation is to consider the matrix converter as a two- stage transformation converter. This separation allows known PWM strategies to be implemented in both the rectifier and the inverter stage. During each sampling interval, DSP will first start the on board A/D converter to sample the input three phase voltages, then make them through comparators to determine the sector code of the input voltage vector. According to the displacement angle set, the switching table is formulated. At last, DSP converts the switching times data to switching pulses, and then sends the sector codes to the PLD (Programmable Logic Device) board. In DSP, the duty cycles of the five switching combinations are calculated and PWM pulses are generated. PLD will deliver the pulses to the appropriate bidirectional switches and fulfil the four- stepped commutation.Block diagram of the proposed DSP controller based matrix converter for induction motor control is shown in figure 3. Fig. 3: Flowchart of proposed approach Modulation synthesize the output voltages from the input voltages and the input currents from the output currents. The first modulator proposed for Matrix Converters, known as the Venturini modulation, employed a scalar model. This model gives a maximum voltage transfer ratio of 0.5. An injection of a third harmonic of the input and output voltage was proposed in order to fit the reference output voltage in the input system envelope. This technique is used to achieve a voltage transfer ratio with a maximum value of 0.866. The three phase matrix converter can be represented by a 3 by 3 matrix form because the nine bidirectional switches can connect one input phase to one output phase directly without any intermediate energy storage elements. Both power stages are directly connected through virtual dc-link and inherently provide bidirectional power flow capability because of its symmetrical topology. IV. DSP-BASED SVM ALGORITHM IMPLEMENTATION The general requirements for generating the switch control signals for a matrix converter on-line in real-time are as follows: i). Computation of the switch duty cycles must be completed within one switching period. ii). Accurate timing of the pulse-pattern output should be achieved, and iii). The computational process must be synchronized with the input-voltage sinusoidal cycle. For both modulation methods, a TMS320F30 digital signal processor was used for on-line calculation of the switch timings. The DSP is mounted on A PC- compatible card, the Evaluation Module (EVM) to facilitate the development process . An additional interface card was used for outputting the calculated
- 4. International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015] ISSN : 2454-1311 www.ijaems.com Page | 4 the same as the input L-C filter, which gives some freedom to the user to change the parameters and configuration for the passive components. For evaluating the performance of the algorithm of proposed method following parameters are used. 4.1 Experimental Setup The complete simulationmodel for induction motor fed by a three phase matrix converter through an indirect space vector modulation approach is shown in figure 4. Fig. 4: SVM Based simulation model for induction motor fed by a three phase matrix converter The MC is used to drive a standard induction motor having the following parameters shown in table 1. Table 1: Motor Parameters Voltage 400 V Nominal Power 4 Kw Frequency 50Hz Pole Pair 2 Torque 20 Rotation Inertia . 0.0131 Kg·m² Stator Resistance (Rs) 0.3578Ω Rotor Resistance (R’r) 0.2861Ω Stator Inductance (Ls) 0.03972H Rotor Resistance (L’r) 0.03972H Mutual Inductance (Lm) 0.03841H The simulations have been carried out assuming a sampling frequency of 2μs and ideal switching devices. The dynamic behavior of the system has been tested with reference to a load step change response and impact speed response. Some simulation studies have been done using system parameters in Table 2. Table 2: Input Parameters Source voltage amplitude, Vin 220 V Input frequency, fi 50 Hz Input filter inductance, Lf 3 mH Input filter capacitance, Cf 25 μF Switching frequency, fs 6 kHz The results found using MATLAB/SIMULINK are validated by performing experiments on available laboratory kit and are shown in the following section. The experimental setup of matrix converter prototype and the main circuit as well as power-control-isolation module of prototype with measuring instruments are shown in Figure 5. Fig. 5: Experimental set-up of the matrix converter drive system For this, a 230V, 250VA three phase to three phase MC fed induction motor drive prototype is implemented using DSP based controller and tests have been carried out to evaluate and improve the stability of system under various typical abnormal input voltage conditions. Digital storage oscilloscope & power quality analyzer are used for experimental observations. For the purpose of generating various AC voltages, an AC source equipment-Elgar SW5253A is used which generates three phase output voltages with various amplitudes, various frequency and various waveforms. The equivalent circuit parameters of the test motor are obtained through light running and blocked rotor tests. Effect of saturation on magnetizing reactance has been found from zero slip tests.
- 5. International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015] ISSN : 2454-1311 www.ijaems.com Page | 5 V. RESULTS AND DISCUSSION Performance of Matrix Converter fed induction motor drive under abnormal input frequency and voltage conditions of power supply is analyzed. These abnormal conditions of input power supply have a great influence on the input/output performance of induction drive. Fig. shows motor performance curves due to drop in supply frequency from 50 to 30 Hz for 1 sec. Sudden drop in frequency cause drop in speed of motor and reaches steady state speed at 0.95 secs shown in figure 6. Time(sec) (a) Time(sec) (b) (c) (d) Fig. 6 (a) Speed and load Torque Response (b) Stator and Rotor Current (c) Input Current (d) Output Current at Abnormal input supply The high performance matrix converter gives a very rapid response to sudden input frequency drop for few seconds. The rapid recovery of the stator and rotor current to this dynamic event is also clearly shown in figure 6(b). It first oscillates with the rapidly varying current before achieving steady-state. The speed of recovery is extremely fast, as stability is reached within few switching cycles.After evaluating the performance of the system under 20% step change in frequency using Simulink, it is validated by the experimental results.It is observed that the obtained experimental results are similar to the simulation results. 5.1 Results under Abnormal Input Voltage Conditions Fig. 7 and 8 show the input/ output current & voltages, when system is operated with unbalanced power supply. The rms values of the input three-phase voltages are 72.6V, 109.8V and 128.2V respectively. Time(sec) OutputCurrent(A) Rotorcurrent(A)Statorcurrent(A) Torque(Nm)Speed(rad/sec) InputCurrent(A) Time(sec) Time(sec)
- 6. International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-1, Issue-7, Oct- 2015] ISSN : 2454-1311 www.ijaems.com Page | 6 Fig. 7: Input & Output phase voltage at 30 Hz. Fig. 8: Output line current at 30 Hz. Fig. 9: Output line voltage. AC source provides 450mS of blackout of the three phase voltages. Fig.9 shows the matrix converter output line voltage. It demonstrate rapid re-starting capability of matrix converter indicating that during the power interruption the power delivered to load is interrupted , however, following the line voltage restoration, the matrix converter rapidly resumes operation and delivers power quickly as compared to PWM converters. VI. CONCLUSION Modeling of the system is developed including modeling of induction motor and DSP controlled matrix converter structure.The paper presented indirect space vector modulation technique for three phase-to-three phase matrix converter. The resulting expressions of the modulation signals are simple and suitable for practical implementation. Besides, it is general that it can be used for unbalanced input voltages. REFERENCES [1] Venugopal, C., "Fuzzy logic based DTC for speed control of Matrix Converter fed Induction Motor," Power and Energy (PECon), 2010 IEEE International Conference on , vol., no., pp.753,758, Nov. 29 2010-Dec. 1 2010. [2] Correa, P.; Rodriguez, J.; Rivera, M.; Espinoza, J.R.; Kolar, J.W., "Predictive Control of an Indirect Matrix Converter," Industrial Electronics, IEEE Transactions on , vol.56, no.6, pp.1847,1853, June 2009 [3] Kumar, V.; Joshi, R. R., "DSP-Based Matrix Converter Operation Under Various Abnormal Conditions with Practicality," Power Electronics, Drives and Energy Systems, 2006. PEDES '06. International Conference on , vol., no., pp.1,4, 12-15 Dec. 2006. [4] Vargas, R.; Ammann, U.; Rodriguez, J.; Pontt, J., "Predictive Strategy to Control Common-Mode Voltage in Loads Fed by Matrix Converters," Industrial Electronics, IEEE Transactions on , vol.55, no.12, pp.4372,4380, Dec. 2008 [5] Wheeler, P.W.; Clare, J.C.; Apap, M.; Bradley, K.J., "Harmonic Loss Due to Operation of Induction Machines From Matrix Converters," Industrial Electronics, IEEE Transactions on , vol.55, no.2, pp.809,816, Feb. 2008 [6] Faraji, V.; Aghasi, M.; Khaburi, D.A.; Ghorbani, M.J., "A modified DTC for induction motor drive system fed by Indirect Matrix Converter using Active Learning Method," Power Electronics, Drive Systems and Technologies Conference (PEDSTC), 2011 2nd , vol., no., pp.356,361, 16-17 Feb. 2011 [7] Reusser, C.A.; Silva, C.A.; Dominguez, P., "Low frequency sensorless Field Oriented Control of an induction machine fed by a direct matrix converter," Industrial Electronics Society, IECON 2013 - 39th Annual Conference of the IEEE , vol., no., pp.4874,4879, 10-13 Nov. 2013 [8] Lopez, M.; Rivera, M.; Garcia, C.; Rodriguez, J.; Pena, R.; Espinoza, J.; Wheeler, P., "Predictive torque control of a multi-drive system fed by a six- leg indirect matrix converter," Industrial Technology (ICIT), 2013 IEEE International Conference on , vol., no., pp.1642,1647, 25-28 Feb. 2013 [9] Metidji, B.; Taib, N.; Baghli, L.; Rekioua, T.; Bacha, S., "Novel Single Current Sensor Topology for Venturini Controlled Direct Matrix Converters," Power Electronics, IEEE Transactions on, vol.28, no.7, pp. 3509, 3516, July 2013.
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