A Review of Analysis and Modeling of Grid Connected Three Phase Multilevel Unity Power Rectifier with Less Component Counts
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This document reviews a five-level multiple-pole structure for a grid connected three phase multilevel unity power rectifier that aims to improve power factor and reduce total harmonic distortion using fewer components. The proposed design is a five-level/multiple-pole multilevel unity power factor rectifier that achieves unity power factor and input current shaping with a reduced number of components. It uses a simple control method based on average current control at a low switching frequency to compensate for grid current harmonics. Simulation results show the design has better dynamic response and tracking under unbalanced grid conditions compared to other existing rectifier topologies.
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 327
A Review of Analysis and Modeling of Grid Connected Three Phase
Multilevel Unity Power Rectifier with Less Component Counts
1Umashankar Verma, 2Ritesh Diwan
1M.Tech Scholar (Power Electronics) Department of Electronics and Telecommunication Engineering, RITEE,
Raipur (C.G)
2Associate professor, Department of Electronics and Telecommunication Engineering , RITEE, Raipur (C.G.)
----------------------------------------------------------------------***---------------------------------------------------------------------
Abstract: In this project, a five level multiple-pole structure
based a simple model is designed to improve power factor, to
reduce total harmonic distortionandtheefficiencyimprove by
using reducing number of components counts. The proposed
method is used to design this project isfive-level/multiple-pole
multilevel unity power rectifier (5L-M2UPFR). There are
several method that has already been designwhich givebetter
response but with more number of component counts. By this
method, the unity power and inputcurrentshapingisachieved
with reduced number of measurement components. Some
addition controller is used in the implementation of grid
voltage observer to get dynamic response and under
unbalanced grid condition the better tracking is achieved.
Key words: Vienna Rectifier, 5L-M2UPFR, Power factor,
average current control (ACC), Electrical Grid.
1. INTRODUCTION
An electrical grid is an interconnected community for
turning in electricity fromproviderstocustomers.Itincludes
producing stations that produce electric strength, high-
voltage transmission strains that carrystrengthfromdistant
assets to call for facilities, and distribution strains that
connect person customers [1]. Powerstationsmaybe placed
near a gasoline supply, at a dam site, or to take advantage of
renewable strength assets, and are frequently positioned
away from closely populated areas. Multilevel converters
have become greater appealing for lots industry and
academia research. Most of the commercially to be had
multilevel inverters require a bulky section-shifted
transformer with multiple bridge rectifiers linked at the
front-stop aspect [1, 2]. However, the quantity and the load
of such configuration are large and heavy. In addition, more
losses are skilled in the transformer during low utilization
because of its middle resistance [3, 4]. Several new
transformers less multilevel rectifier topologies with low
switching frequency operation had been reported in the
literature. The referred to low-cost topologies have
performedaccurateperformanceandadditionallyconfirmed
that the clear out length may be extensively reduced in spite
of the low switching frequency operation. However, each of
those topologies has its limitations and disadvantages. For
example, a complex manipulate algorithm is needed to
stability the flying capacitors of the three-section megastar-
configured PUC topology. While in the case of RPC-DCR
topology, simplest two switches are decreased in each
phase-leg however the general aspectcountsarenotnotably
optimized. Hence, large wide variety of gate drivers and
remote gate supplies are still required. As for the DCLP-FC
topology, a very good arrangement of hybrid technique is
delivered to reduce 50% of the switching gadgets compared
with both conventional diode clamped and flying capacitor
rectifiers. Nevertheless, a complete of eight dc capacitors is
nevertheless neededforthis3-sectiontopologytosynthesize
a 5-stage segment voltage stepped waveform. Due to the
involvement of dc electrolytic capacitors, the lifetime of the
power converter will ultimately be suffering from the
thermal getting old. This paper offers a new value-effective
transformer less a couple of poles multilevel unity power
thing rectifiers (M2UPFR). The proposed three-phase
M2UPFR makes use of simplest six switches to synthesize a
5-stage enter segment voltage stepped waveform,
consequently the aspect counts are substantially reduced. A
low switching frequency operation with the common
cutting-edge control (ACC) method is applied for the grid
modern harmonic reimbursement.
Moreover, the manage set of rules is developed with
observer method. Thus, a decrease cost solution is finished
with the discount of measurement sensors needed for the
remarks manage loop not like the proposed switching
method provided in [5]. In addition to that, top notch
dynamic reaction is demonstrated with the expected
performances of both grid voltage and load modern-day
during unbalanced grid condition.](https://image.slidesharecdn.com/irjet-v4i659-180122063108/85/A-Review-of-Analysis-and-Modeling-of-Grid-Connected-Three-Phase-Multilevel-Unity-Power-Rectifier-with-Less-Component-Counts-1-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 328
2. Objective
The main objective of this work is design a model to obtain
better efficiency with less total harmonic distortion and
improvise power factor using less component counts. To
design a cost effective transformer lessa coupleofpoleunity
power factor rectifier.
3. Problem statement
From the study of various algorithm designed earlier,
various problem such as bulky model due to heavy
transformer, at high frequency the switching losses are
dominant, the output power range also effected, less power
factor, more total harmonicsdistortion,sometimes efficiency
also reduced. In this paper, in this paper we are focusing on
power factor and the total harmonic distortion of output
power.
4. FIVE-LEVEL MULTIPLE-POLE UNITY POWER
FACTOR RECTIFIER TOPOLOGY
4.1 Basic Operating Principle
A 5-stage (5L) M2UPFR topologywithbalancedload
is shown in Fig. 1 is built the usage of three-level (3L)
VIENNA rectifier cells in each phase-leg. The multiple-pole
multilevel diode-clamped inverter concept is similar to the
multiple pole structure [6]. Hence, the output terminals of
both VIENNA rectifier cells are linked to the respective dc
capacitors with the resource of balancing circuit as
distinctive in [7, 8]. Based on switching state selection and
the direction of phase current the overall performance of
this method is synthesized in which each cell is
characterized with the three level input voltage stepped
waveform. The proposed five-level (5L) multiple-pole
VIENNA rectifier (MVR) presented in this paper (Fig.1)
achieves a good overall performance with reduced number
of components while operating at lower switching
frequency. The balanced voltage across the dc-link
capacitors and precise operation of bidirectional switches
synthesizes a fivelevel stepped input voltage waveform.
Thus, low input current distortion and high input power
factor are achieved. The requirement of input line
inductance is as well reduced due to lower THD.
Fig 1: Unidirectional 5L-M2UPFR with the balancing
circuit
4.2 Controller Design
4.2.1 Unity Power Factor Control
This power factor control both load current and grid voltage
which can be seen in the circuit diagram below. The
controller structure is constructed using synchronous
reference frame (SRF) current control [9]. The complicated
phase locked loop design is used in d-q transformation to
limit control bandwidth.
Fig. 2: Block diagram of the unity power factor controller
with the grid voltage and load current observers
The dc-link voltage control carried at outer loop andcurrent
control carried at the inner loop [6]. The dc equivalent
capacitors current is calculatedbytheouterloopcontrol and
regulates the output dc link voltage. Meanwhile, the load
current is formulated from the power balanced principle.](https://image.slidesharecdn.com/irjet-v4i659-180122063108/85/A-Review-of-Analysis-and-Modeling-of-Grid-Connected-Three-Phase-Multilevel-Unity-Power-Rectifier-with-Less-Component-Counts-2-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 329
Fig 3: The Load current observer
4.2.2 Voltage Control
The dc-link voltage is regulated with a simple proportional –
integral controller which is expressed as follows
Where, Kp is the proportional gain of the dc-link voltage
regulator and ti is the settling time of the dc-link voltage
tracking and the approximation value of Kp is obtained from
the energy storage model. According to stability criteria, the
proportional gain of the control system expressed in below
equation.
4.2.3 Current Control
The grid current control technique of the active
rectifier can be classified into four categories such as space
vector modulation (SVM) [10, 11], fix hysteresis band
current control (FHBCC) [9, 12], variable hysteresis band
current control [13] and ACC [12, 14]. The SVM scheme
requires high computational effortduetothecomplexsector
control algorithm required for higher voltage stepped level
rectifier topology [15]. Both HBCC and ACC can overcome
the stated problems of SVM scheme. However, FHBCC
scheme exhibits the disadvantage of variable switching
frequency which complicates the design of the input
inductance filter.
Fig 4: Energy stored model
Fig 5: Peak detector of the grid voltage for the reference
sinusoidal wave
The carrier-based ACC scheme is applied for the proposed
5L-M2UPFR and allows the desired voltage space vector to
be modulated using simple analogue comparators. By doing
so, lower cost implementation and lesser computational
effort needed are achieved.
4.2.4 Grid Voltage
Several observer strategies had been proposed for
numerous varieties of rectifier configuration [16-18].
Besides the benefit of disposing of the sensors needed, the
observer approach reduces the size of converterandoffersa
lower production cost as well. Even though the statistics of
three phase grid currents are enough to derive and estimate
the ac and dc voltages, but huge dc hyperlink voltage ripples
are experienced throughout the computational manner.
Hence, inflicting high enter cutting edge total harmonic
distortion (THD) inside the grid.
Fig 6: Grid voltage observer
5. CONCLUSION
The proposed 5L-M2UPFR method provides higher
reliability of three phase power supply at extreme
unbalanced condition of grid. The reduction in sensor
improves system failures and by this method unity power
factor with less total harmonics distortion is obtained. Most
important is that we can design light weight and high power
density using this method.](https://image.slidesharecdn.com/irjet-v4i659-180122063108/85/A-Review-of-Analysis-and-Modeling-of-Grid-Connected-Three-Phase-Multilevel-Unity-Power-Rectifier-with-Less-Component-Counts-3-320.jpg)
![International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 330
ACKNOWLEDGEMENT
Expression of giving thanks are just a part of those feeling
which are too large for words, but shall remain as memories
of wonderful people with whom I have got the pleasure of
working during the completion of this work. I am grateful to
RITEE, Raipur (C.G.) which helped me to complete my work
by giving encouraging environment. I would like to express
my deep and sincere gratitude to my supervisor, Associate
Professor Ritesh Diwan . His/her wide knowledge and his
logical way of thinking have been of great value for me.
His/her understanding, encouraging and personal guidance
have provided a good basis for the present work.
REFERENCES
[1]. Kouro, S., Malinowski, M., Gopakumar, K., et al.: ‘Recent
advances and industrial applications of multilevel
converters’, IEEE Trans. Ind. Electron., 2010, 57, pp. 2553–
2580.
[2]. Miranbeigi, M., Iman-Eini, H., Asoodar, M.: ‘A new
switching strategy for transformer-less back-to-back
cascaded H-bridge multilevel converter’, IET Power
Electron., 2014, 7, pp. 1868–1877.
[3]. Daher, S., Schmid, J., Antunes, F.L.M.: ‘Multilevel inverter
topologies for stand-alone PV systems’, IEEE Trans. Ind.
Electron., 2008, 55, pp. 2703–2712.
[4]. Steimer, P.K., Winkelnkemper, M.: Transformerless
multi-level converter based medium voltage drives’. 2011
IEEE Energy Conversion Congress and Exposition (ECCE),
2011, pp. 3435–3441.
[5]. Gabriel, O.H.P., Maswood, A.I., Ziyou, L., et al.: ‘Input
current shaping of five-level multiple-pole VIENNA rectifier
topologies with reduced component and better
performance’. Presented at the 39thAnnual Conf.oftheIEEE
Industrial Electronics Society, IECON 2013–, 2013.
[6]. Ooi, G.H.P., Maswood, A.I., Ziyou, L.: ‘Five-level multiple-
pole PWM AC-AC converters with reduced components
count’, IEEE Trans. Ind. Electron., 2015, 62, pp. 4739–4748.
[7]. Hatti, N., Kondo, Y., Akagi, H.: ‘Five-level diode-clamped
PWM converters connected back-to-back for motor drives’,
IEEE Trans. Ind. Appl., 2008, 44, pp. 1268–1276.
[8]. Ajami, A., Shokri, H., Mokhberdoran, A.: ‘Parallel switch-
based chopper circuit for DC capacitor voltage balancing in
diode-clamped multilevel inverter’, IET Power Electron.,
2014, 7, pp. 503–514.
[9]. Maswood, A.I., Fangrui, L.: ‘A unity-power-factor
converter using the synchronous reference-frame-based
hysteresis current control’, IEEE Trans. Ind. Appl., 2007, 43,
pp. 593–599.
[10]. Barbi, I., Batista, F.A.B.: ‘Space vector modulation for
two-level unidirectional PWM rectifiers’, IEEE Trans. Power
Electron., 2010, 25, pp. 178–187.
[11]. Raj, P.H., Maswood, A.I., Ooi, G.H.P., et al.: ‘Voltage
balancing technique in a space vector modulated 5-level
multiple-pole multilevel diode clamped inverter’,IETPower
Electron., 2015, 8, pp. 1263–1272.
[12]. Maswood, A.I., Al-Ammar, E., Liu, F.: ‘Average and
hysteresis current-controlled three-phase three-level unity
power factor rectifier operation and performance’, IET
Power Electron., 2011, 4, pp. 752–758.
[13]. Fangrui, L., Maswood, A.I.: ‘A novel variable hysteresis
band current control of three-phase three-level unity PF
rectifier with constant switching frequency’, IEEE Trans.
Power Electron., 2006, 21, pp. 1727–1734.
[14]. Jong-Won, S., Bo-Hyung, C.: ‘Digitally implemented
average current-mode control in discontinuous conduction
mode PFC rectifier’, IEEE Trans. Power Electron., 2012, 27,
pp. 3363–3373.
[15]. Ide, P., Froehleke, N., Grotstollen, H.: ‘Investigation of
low cost control schemes for a selected 3-level switched
mode rectifier’. Ninteeth Int. Telecommunications Energy
Conf., 1997. INTELEC 97, 1997, pp. 413–418.
[16]. Ohnuki, T., Miyashita, O., Lataire, P., et al.: ‘Control of a
three-phase PWM rectifier using estimated AC-side and DC-
side voltages’, IEEE Trans. Power Electron., 1999, 14, pp.
222–226.
[17]. Wang, B., Venkataramanan, G., Bendre, A.:‘Unitypower
factor control for three-phase three-level rectifiers without
current sensors’, IEEE Trans. Ind. Appl., 2007, 43, pp. 1341–
1348.
[18 ]. Ghosh, R., Narayanan, G.: ‘Generalized feed forward
control of single-phase PWM rectifiers using disturbance
observers’, IEEE Trans. Ind. Electron., 2007, 54, pp. 984–
993.](https://image.slidesharecdn.com/irjet-v4i659-180122063108/85/A-Review-of-Analysis-and-Modeling-of-Grid-Connected-Three-Phase-Multilevel-Unity-Power-Rectifier-with-Less-Component-Counts-4-320.jpg)
A Review of Analysis and Modeling of Grid Connected Three Phase Multilevel Unity Power Rectifier with Less Component Counts
- 1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 327 A Review of Analysis and Modeling of Grid Connected Three Phase Multilevel Unity Power Rectifier with Less Component Counts 1Umashankar Verma, 2Ritesh Diwan 1M.Tech Scholar (Power Electronics) Department of Electronics and Telecommunication Engineering, RITEE, Raipur (C.G) 2Associate professor, Department of Electronics and Telecommunication Engineering , RITEE, Raipur (C.G.) ----------------------------------------------------------------------***--------------------------------------------------------------------- Abstract: In this project, a five level multiple-pole structure based a simple model is designed to improve power factor, to reduce total harmonic distortionandtheefficiencyimprove by using reducing number of components counts. The proposed method is used to design this project isfive-level/multiple-pole multilevel unity power rectifier (5L-M2UPFR). There are several method that has already been designwhich givebetter response but with more number of component counts. By this method, the unity power and inputcurrentshapingisachieved with reduced number of measurement components. Some addition controller is used in the implementation of grid voltage observer to get dynamic response and under unbalanced grid condition the better tracking is achieved. Key words: Vienna Rectifier, 5L-M2UPFR, Power factor, average current control (ACC), Electrical Grid. 1. INTRODUCTION An electrical grid is an interconnected community for turning in electricity fromproviderstocustomers.Itincludes producing stations that produce electric strength, high- voltage transmission strains that carrystrengthfromdistant assets to call for facilities, and distribution strains that connect person customers [1]. Powerstationsmaybe placed near a gasoline supply, at a dam site, or to take advantage of renewable strength assets, and are frequently positioned away from closely populated areas. Multilevel converters have become greater appealing for lots industry and academia research. Most of the commercially to be had multilevel inverters require a bulky section-shifted transformer with multiple bridge rectifiers linked at the front-stop aspect [1, 2]. However, the quantity and the load of such configuration are large and heavy. In addition, more losses are skilled in the transformer during low utilization because of its middle resistance [3, 4]. Several new transformers less multilevel rectifier topologies with low switching frequency operation had been reported in the literature. The referred to low-cost topologies have performedaccurateperformanceandadditionallyconfirmed that the clear out length may be extensively reduced in spite of the low switching frequency operation. However, each of those topologies has its limitations and disadvantages. For example, a complex manipulate algorithm is needed to stability the flying capacitors of the three-section megastar- configured PUC topology. While in the case of RPC-DCR topology, simplest two switches are decreased in each phase-leg however the general aspectcountsarenotnotably optimized. Hence, large wide variety of gate drivers and remote gate supplies are still required. As for the DCLP-FC topology, a very good arrangement of hybrid technique is delivered to reduce 50% of the switching gadgets compared with both conventional diode clamped and flying capacitor rectifiers. Nevertheless, a complete of eight dc capacitors is nevertheless neededforthis3-sectiontopologytosynthesize a 5-stage segment voltage stepped waveform. Due to the involvement of dc electrolytic capacitors, the lifetime of the power converter will ultimately be suffering from the thermal getting old. This paper offers a new value-effective transformer less a couple of poles multilevel unity power thing rectifiers (M2UPFR). The proposed three-phase M2UPFR makes use of simplest six switches to synthesize a 5-stage enter segment voltage stepped waveform, consequently the aspect counts are substantially reduced. A low switching frequency operation with the common cutting-edge control (ACC) method is applied for the grid modern harmonic reimbursement. Moreover, the manage set of rules is developed with observer method. Thus, a decrease cost solution is finished with the discount of measurement sensors needed for the remarks manage loop not like the proposed switching method provided in [5]. In addition to that, top notch dynamic reaction is demonstrated with the expected performances of both grid voltage and load modern-day during unbalanced grid condition.
- 2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 328 2. Objective The main objective of this work is design a model to obtain better efficiency with less total harmonic distortion and improvise power factor using less component counts. To design a cost effective transformer lessa coupleofpoleunity power factor rectifier. 3. Problem statement From the study of various algorithm designed earlier, various problem such as bulky model due to heavy transformer, at high frequency the switching losses are dominant, the output power range also effected, less power factor, more total harmonicsdistortion,sometimes efficiency also reduced. In this paper, in this paper we are focusing on power factor and the total harmonic distortion of output power. 4. FIVE-LEVEL MULTIPLE-POLE UNITY POWER FACTOR RECTIFIER TOPOLOGY 4.1 Basic Operating Principle A 5-stage (5L) M2UPFR topologywithbalancedload is shown in Fig. 1 is built the usage of three-level (3L) VIENNA rectifier cells in each phase-leg. The multiple-pole multilevel diode-clamped inverter concept is similar to the multiple pole structure [6]. Hence, the output terminals of both VIENNA rectifier cells are linked to the respective dc capacitors with the resource of balancing circuit as distinctive in [7, 8]. Based on switching state selection and the direction of phase current the overall performance of this method is synthesized in which each cell is characterized with the three level input voltage stepped waveform. The proposed five-level (5L) multiple-pole VIENNA rectifier (MVR) presented in this paper (Fig.1) achieves a good overall performance with reduced number of components while operating at lower switching frequency. The balanced voltage across the dc-link capacitors and precise operation of bidirectional switches synthesizes a fivelevel stepped input voltage waveform. Thus, low input current distortion and high input power factor are achieved. The requirement of input line inductance is as well reduced due to lower THD. Fig 1: Unidirectional 5L-M2UPFR with the balancing circuit 4.2 Controller Design 4.2.1 Unity Power Factor Control This power factor control both load current and grid voltage which can be seen in the circuit diagram below. The controller structure is constructed using synchronous reference frame (SRF) current control [9]. The complicated phase locked loop design is used in d-q transformation to limit control bandwidth. Fig. 2: Block diagram of the unity power factor controller with the grid voltage and load current observers The dc-link voltage control carried at outer loop andcurrent control carried at the inner loop [6]. The dc equivalent capacitors current is calculatedbytheouterloopcontrol and regulates the output dc link voltage. Meanwhile, the load current is formulated from the power balanced principle.
- 3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 329 Fig 3: The Load current observer 4.2.2 Voltage Control The dc-link voltage is regulated with a simple proportional – integral controller which is expressed as follows Where, Kp is the proportional gain of the dc-link voltage regulator and ti is the settling time of the dc-link voltage tracking and the approximation value of Kp is obtained from the energy storage model. According to stability criteria, the proportional gain of the control system expressed in below equation. 4.2.3 Current Control The grid current control technique of the active rectifier can be classified into four categories such as space vector modulation (SVM) [10, 11], fix hysteresis band current control (FHBCC) [9, 12], variable hysteresis band current control [13] and ACC [12, 14]. The SVM scheme requires high computational effortduetothecomplexsector control algorithm required for higher voltage stepped level rectifier topology [15]. Both HBCC and ACC can overcome the stated problems of SVM scheme. However, FHBCC scheme exhibits the disadvantage of variable switching frequency which complicates the design of the input inductance filter. Fig 4: Energy stored model Fig 5: Peak detector of the grid voltage for the reference sinusoidal wave The carrier-based ACC scheme is applied for the proposed 5L-M2UPFR and allows the desired voltage space vector to be modulated using simple analogue comparators. By doing so, lower cost implementation and lesser computational effort needed are achieved. 4.2.4 Grid Voltage Several observer strategies had been proposed for numerous varieties of rectifier configuration [16-18]. Besides the benefit of disposing of the sensors needed, the observer approach reduces the size of converterandoffersa lower production cost as well. Even though the statistics of three phase grid currents are enough to derive and estimate the ac and dc voltages, but huge dc hyperlink voltage ripples are experienced throughout the computational manner. Hence, inflicting high enter cutting edge total harmonic distortion (THD) inside the grid. Fig 6: Grid voltage observer 5. CONCLUSION The proposed 5L-M2UPFR method provides higher reliability of three phase power supply at extreme unbalanced condition of grid. The reduction in sensor improves system failures and by this method unity power factor with less total harmonics distortion is obtained. Most important is that we can design light weight and high power density using this method.
- 4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 330 ACKNOWLEDGEMENT Expression of giving thanks are just a part of those feeling which are too large for words, but shall remain as memories of wonderful people with whom I have got the pleasure of working during the completion of this work. I am grateful to RITEE, Raipur (C.G.) which helped me to complete my work by giving encouraging environment. I would like to express my deep and sincere gratitude to my supervisor, Associate Professor Ritesh Diwan . His/her wide knowledge and his logical way of thinking have been of great value for me. His/her understanding, encouraging and personal guidance have provided a good basis for the present work. REFERENCES [1]. Kouro, S., Malinowski, M., Gopakumar, K., et al.: ‘Recent advances and industrial applications of multilevel converters’, IEEE Trans. Ind. Electron., 2010, 57, pp. 2553– 2580. [2]. Miranbeigi, M., Iman-Eini, H., Asoodar, M.: ‘A new switching strategy for transformer-less back-to-back cascaded H-bridge multilevel converter’, IET Power Electron., 2014, 7, pp. 1868–1877. [3]. Daher, S., Schmid, J., Antunes, F.L.M.: ‘Multilevel inverter topologies for stand-alone PV systems’, IEEE Trans. Ind. Electron., 2008, 55, pp. 2703–2712. [4]. Steimer, P.K., Winkelnkemper, M.: Transformerless multi-level converter based medium voltage drives’. 2011 IEEE Energy Conversion Congress and Exposition (ECCE), 2011, pp. 3435–3441. [5]. Gabriel, O.H.P., Maswood, A.I., Ziyou, L., et al.: ‘Input current shaping of five-level multiple-pole VIENNA rectifier topologies with reduced component and better performance’. Presented at the 39thAnnual Conf.oftheIEEE Industrial Electronics Society, IECON 2013–, 2013. [6]. Ooi, G.H.P., Maswood, A.I., Ziyou, L.: ‘Five-level multiple- pole PWM AC-AC converters with reduced components count’, IEEE Trans. Ind. Electron., 2015, 62, pp. 4739–4748. [7]. Hatti, N., Kondo, Y., Akagi, H.: ‘Five-level diode-clamped PWM converters connected back-to-back for motor drives’, IEEE Trans. Ind. Appl., 2008, 44, pp. 1268–1276. [8]. Ajami, A., Shokri, H., Mokhberdoran, A.: ‘Parallel switch- based chopper circuit for DC capacitor voltage balancing in diode-clamped multilevel inverter’, IET Power Electron., 2014, 7, pp. 503–514. [9]. Maswood, A.I., Fangrui, L.: ‘A unity-power-factor converter using the synchronous reference-frame-based hysteresis current control’, IEEE Trans. Ind. Appl., 2007, 43, pp. 593–599. [10]. Barbi, I., Batista, F.A.B.: ‘Space vector modulation for two-level unidirectional PWM rectifiers’, IEEE Trans. Power Electron., 2010, 25, pp. 178–187. [11]. Raj, P.H., Maswood, A.I., Ooi, G.H.P., et al.: ‘Voltage balancing technique in a space vector modulated 5-level multiple-pole multilevel diode clamped inverter’,IETPower Electron., 2015, 8, pp. 1263–1272. [12]. Maswood, A.I., Al-Ammar, E., Liu, F.: ‘Average and hysteresis current-controlled three-phase three-level unity power factor rectifier operation and performance’, IET Power Electron., 2011, 4, pp. 752–758. [13]. Fangrui, L., Maswood, A.I.: ‘A novel variable hysteresis band current control of three-phase three-level unity PF rectifier with constant switching frequency’, IEEE Trans. Power Electron., 2006, 21, pp. 1727–1734. [14]. Jong-Won, S., Bo-Hyung, C.: ‘Digitally implemented average current-mode control in discontinuous conduction mode PFC rectifier’, IEEE Trans. Power Electron., 2012, 27, pp. 3363–3373. [15]. Ide, P., Froehleke, N., Grotstollen, H.: ‘Investigation of low cost control schemes for a selected 3-level switched mode rectifier’. Ninteeth Int. Telecommunications Energy Conf., 1997. INTELEC 97, 1997, pp. 413–418. [16]. Ohnuki, T., Miyashita, O., Lataire, P., et al.: ‘Control of a three-phase PWM rectifier using estimated AC-side and DC- side voltages’, IEEE Trans. Power Electron., 1999, 14, pp. 222–226. [17]. Wang, B., Venkataramanan, G., Bendre, A.:‘Unitypower factor control for three-phase three-level rectifiers without current sensors’, IEEE Trans. Ind. Appl., 2007, 43, pp. 1341– 1348. [18 ]. Ghosh, R., Narayanan, G.: ‘Generalized feed forward control of single-phase PWM rectifiers using disturbance observers’, IEEE Trans. Ind. Electron., 2007, 54, pp. 984– 993.