Discontinuous modulation scheme for a differential mode cuk inverter

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IEEE SOFTWARE | EMBEDDED | MECHANICAL | ROBOTICS PROJECTS DEVELOPMENT
DISCONTINUOUS MODULATION SCHEME FOR A DIFFERENTIAL-MODE CUK
INVERTER
By
A
PROJECT REPORT
Submitted to the Department of electronics & communication Engineering in the
FACULTY OF ENGINEERING & TECHNOLOGY
In partial fulfillment of the requirements for the award of the degree
Of
MASTER OF TECHNOLOGY
IN
ELECTRONICS & COMMUNICATION ENGINEERING
APRIL 2016

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CERTIFICATE
Certified that this project report titled “DISCONTINUOUS MODULATION SCHEME FOR
A DIFFERENTIAL-MODE CUK INVERTER” is the bonafide work of Mr.
_____________Who carried out the research under my supervision Certified further, that to the
best of my knowledge the work reported herein does not form part of any other project report or
dissertation on the basis of which a degree or award was conferred on an earlier occasion on this
or any other candidate.
Signature of the Guide Signature of the H.O.D
Name Name

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DECLARATION
I hereby declare that the project work entitled “DISCONTINUOUS MODULATION
SCHEME FOR A DIFFERENTIAL-MODE CUK INVERTER” Submitted to
BHARATHIDASAN UNIVERSITY in partial fulfillment of the requirement for the award of the
Degree of MASTER OF APPLIED ELECTRONICS is a record of original work done by me the
guidance of Prof.A.Vinayagam M.Sc., M.Phil., M.E., to the best of my knowledge, the work
reported here is not a part of any other thesis or work on the basis of which a degree or award
was conferred on an earlier occasion to me or any other candidate.
(Student Name)
(Reg.No)
Place:
Date:
ACKNOWLEDGEMENT

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I am extremely glad to present my project “DISCONTINUOUS MODULATION SCHEME
FOR A DIFFERENTIAL-MODE CUK INVERTER ” which is a part of my curriculum of
third semester Master of Science in Computer science. I take this opportunity to express my
sincere gratitude to those who helped me in bringing out this project work.
I would like to express my Director, Dr. K. ANANDAN, M.A.(Eco.), M.Ed., M.Phil.,(Edn.),
PGDCA., CGT., M.A.(Psy.) of who had given me an opportunity to undertake this project.
I am highly indebted to Co-Ordinator Prof. Muniappan Department of Physics and thank from
my deep heart for her valuable comments I received through my project.
I wish to express my deep sense of gratitude to my guide
Prof. A.Vinayagam M.Sc., M.Phil., M.E., for her immense help and encouragement for
successful completion of this project.
I also express my sincere thanks to the all the staff members of Computer science for their kind
advice.
And last, but not the least, I express my deep gratitude to my parents and friends for their
encouragement and support throughout the project.

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ABSTRACT:
The differential-mode C´ uk inverter (DMCI) is a single-stage inverter with low device
count. It offers advantages over other topologies because of compactness, higher power density,
and reduced cost. It is a promising topological configuration for renewable-/alternative-energy
applications with isolated as well as nonisolated structures. The continuous modulation scheme
(CMS), which was introduced originally for this inverter, activates all the modules of the DMCI.
The new discontinuous modulation scheme (DMS) deactivates one module in each half line-
cycle leading to discontinuous operation of modules. This paper outlines the DMS and a
mechanism to realize it. The experimental open-loop and closed-loop results of the DMCI using
CMS and DMS are provided along with a comparison of their performances. It is shown that, the
DMS reduces the circulating power and hence mitigates the losses. The voltage ratings of the
devices also are reduced with theDMS. In contrast, theCMShaswider linearity in its normalized
dc-voltage gain and yields reduced harmonic distortion of the output voltage. For DMS, to
achieve comparable linearity in normalized dc-voltage gain and distortion, harmonic
compensation under closed-loop control is a pathway that has been demonstrated

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INTRODUCTION:
Typical transformer-less topologies have a cascaded boost–buck or buck–boost
architecture, which may yield common mode leakage current for some applications. For such
applications and others, an isolated HFL inverter topology is a relevant choice.
Kim et al. introduce a bidirectional multistage HFL topology, while the topologies
outlined in support unidirectional power flow. While several HFL-inverter topologies include a
front-end dc–dc converter followed by a decoupling dc capacitor, other multistage topologies
preclude the need for an intermediate dc-link electrolytic capacitor.
Overall, for low-power applications the cost-benefit tradeoff of a multistage HFL inverter
topology requires careful attention. As such, for low-power single-phase HFL inverter
applications, there is an enhanced thrust to seek single-stage topological solutions
Single-stage topologies are categorized, reviewed and compared by literatures Long et al.
present z-source inverter topologies, while introduces C´ uk-derived single-stage topology.
Differential inverters are group of singlestage topologies that consist of parallel-series
connection of two dc converters.
Chen and Wang present differential buck while differential boost is discussed.
Differential flyback is one of the candidate topologies for microinverters with three controlled
devices (with two of them being high-side devices) and three diodes. However, this topology
cannot support bidirectional power flow, which will require additional controllable devices.

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Further current on the secondary side of the bridge is discontinuous in nature. Moreover,
the magnetizing current of the isolation transformers is subjected to linefrequency components
which affect the size of the transformer.
The differential topology introduced by Kjaer and Blaabjerg has the line-frequency
penetration on magnetizing current of transformer problem too. Sivasubramanian and Mazumder
introduce parallel–parallel isolated configurations with C´ uk converter, but with eight
controllable switches.

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EXISTING SYSTEM:
The buck–boost converter is a type of DC-to-DC converter that has an output voltage
magnitude that is either greater than or less than the input voltage magnitude. It is equivalent to
a flyback converter using a single inductor instead of a transformer. The output voltage is of the
opposite polarity than the input. This is a switched-mode power supply with a similar circuit
topology to the boost converter and the buck converter. The output voltage is adjustable based on
the duty cycle of the switching transistor. One possible drawback of this converter is that the
switch does not have a terminal at ground; this complicates the driving circuitry. Neither
drawback is of any consequence if the power supply is isolated from the load circuit (if, for
example, the supply is a battery) because the supply and diode polarity can simply be reversed.
The switch can be on either the ground side or the supply side

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PROPOSED SYSTEM:
The DMCI topology comprises two modules, which are connected in parallel at the dc
side and connected in series at the ac side. The differential-mode inverter comprises limited
number of switches all of which are low-side driven. Further, the inverter has the ability to
support bidirectional power flow using the same set of switches and a seamless control. An
added capability of the HFL C´uk inverter is its ability to support line-frequency ripple current
without a large isolation transformer. Due to the presence of the two blocking capacitors on the
primary and secondary side of the transformer, the magnetizing current of the transformer is
essentially devoid of any line-frequency current component. Finally, the possibility of coupled
inductors and transformer has been introduced, which enhances the compactness of the inverter
and leads to reduced input and output ripples. The original DMCI topology outlined switching of
the inverter using a continuous modulation scheme (CMS), in which diagonal devices switch
simultaneously and continuously. In CMS, one module pulls the power while the other one
pushes it. This leads to circulation of power yielding higher switching and conduction losses.
Further, the continuous modulation of all of the switches implies that a control system for this
inverter sees an eighth-order dynamics under all operating conditions which has adverse
implications on control bandwidth.

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ADVANTAGES:
 Voltage step-up and step-down functionalities.
 Reduced cost.
 Reliability.
 High power density

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BLOCK DIAGRAM:

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TOOLS AND SOFTWARE USED:
 MPLAB – microcontroller programming.
 ORCAD – circuit layout.
 MATLAB/Simulink – Simulation

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APPLICATIONS:
 Drives

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CONCLUSION:
The paper describes a DMS for a DMCI and compares the mechanism and performance
of the DMS-based DMCI to that of a prior-art CMS-based DMCI. An experimental hardware
prototype was developed for the DMCI to validate and compare the results obtained using the
two modulation schemes focusing on energy-conversion efficiency, device rating, output-voltage
distortion, and transient response of the inverter. It has been found that DMS, which leads to
topological switching of the DMCI, yields significant improvement in efficiency of the inverter
compared to that obtained using CMS. This is because DMS eliminates the pathway for
circulating reactive power in the DMCI. For the same reason, the reduction in the voltage rating
of the DMCI switches is also found to be significant using DMS.

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REFERENCES:
[1] H. S. Kim, M. H. Ryu, J. W. Baek, and J. H. Jung, “High-efficiency isolated bidirectional ac–
dc converter for a dc distribution system,” IEEE Trans. Power Electron., vol. 28, no. 4, pp.
1642–1654, Apr. 2013.
[2] S. Harb and R. S. Balog, “Reliability of candidate photovoltaic moduleintegrated- inverter
(PV-MII) topologies—A usagemodel approach,” IEEE Trans. Power Electron., vol. 28, no. 6,
pp. 3019–3027, Jun. 2013.
[3] A. Rahnamaee and S. K.Mazumder, “A soft-switched hybrid-modulation scheme for a dc-
link-capacitor-less three-phase pulsating-dc-link inverter,” IEEE Trans. Power Electron., vol. 28,
no. 8, pp. 3893–3906, Jun. 2014.
[4] S. K.Mazumder, “Anovel hybrid modulation scheme for an isolated highfrequency- link fuel
cell inverter,” in Proc. IEEE Power Energy Soc. Gen. Meet., 2008, pp. 1–7.
[5] H. Bayat, J. S. Moghani, S. H. Fathi, and H. Riazmontazer, “Implementation of a 5 level
cascade H-bridge inverter using PWM strategy with unequal carrier frequency for optimizing
and reducing the switching number,” J. Int. Rev. Elect. Eng., vol. 6, no. 1, pp. 23–29, Feb. 2011

Discontinuous modulation scheme for a differential mode cuk inverter

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Discontinuous modulation scheme for a differential mode cuk inverter