A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> Modelling.- Modelling of DC-to-DC Power Converters.- Controller Design Methods.- Sliding Mode Control.- Approximate Linearization in the Control of Power Electronics Devices.- Nonlinear Methods in the Control of Power Electronics Devices.- Applications.- DC-to-AC Power Conversion.- AC Rectifiers. <s> BIB001 </s> A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorialonthistechnology,coveringtheoperatingprincipleand the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics. <s> BIB002 </s> A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas. <s> BIB003 </s> A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> PV connected to the single phase grid is discussed in this review. Also the types of multilevel inverter is discussed. Normally the line commutated inverter has square shaped waveform of line current. So it has large amount of harmonic and produces excess of heat which causes damage to the winding of transformer. Multilevel inverter gives the output current waveform which is nearly sinusoidal in nature. This line current has fewer harmonics as compared to line commutated inverter. Basically multilevel inverter produces the output by synthesis of DC voltages i.e. by increasing of DC voltages, the levels of the output increases. Multilevel inverter also used for electric drives applications for same reason i.e. harmonic reduction. The simulation can be done by MATLAB/SIMULINK. In simulation model we can use DC source instead of PV module. <s> BIB004 </s> A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> Multilevel inverters have been drawing growing attention in the recent years especially in the distributed energy resources area due to the fact that several batteries, fuel cells, solar cell, wind and micro turbines can be connected through multilevel inverter to feed a load or the ac grid. Multilevel inverter becomes an alternative in the area of high- power medium-voltage energy control. Therefore, Harmonic Reduction in multi level inverters are considered very important task. For eliminating the harmonics lot of researchers have suggested modifications in the circuit topology and optimal selection of firing angle using conventional and nonconventional optimization algorithms. This paper presents a review application by different optimization techniques for harmonic reduction in multilevel inverters. <s> BIB005 </s> A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> Multilevel Inverter widely used in high power industrial applications. This paper presents a new modified cascaded H-Bridge multilevel inverter with reduction of switching component. In traditional CHB inverters required more number of components, it seem to more complex control circuitry and bulky. Since Last few decade the researchers from all over world concentrating to improve the efficiency of Multilevel Inverter such as voltage balancing, reduction in components, modulation methods and control technique etc. The Proposed multilevel inverter output voltage level increasing by using less number of switches driven by the multicarrier modulation techniques. In this paper presents generalized structure, Operation, comparison with other traditional topology, Simulation results with MATLAB/SIMULINK and experimental results. <s> BIB006 </s> A Review of Multilevel Inverter Topology and Control Techniques <s> I. INTRODUCTION <s> This paper deals with the voltage unbalance problem in multilevel inverters. Multilevel voltage source converters are the new trend in the power converter option for high-power applications. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The elimination of voltage unbalance in a single-phase five-level inverter which uses coupled inductors and feedback control, which can produce a five level output voltage with only one dc source. With this topology, splitting of the dc voltage is avoided, which eliminates the problem of voltage balancing in the circuit which was a prominent problem in the conventional topologies. The feedback control of the inverter is implemented using a PI controller. The six power switches used here have the same voltage stress and only one set of coupled inductors are adopted. <s> BIB007
The concept of multilevel inverters (MLI) has been introduced since mid-1970. The term multilevel originated with the three-level inverter. Subsequently, several multilevel inverter topologies continue to emerge, especially in the last two decades. They are powerconversion systems composed by an array of power semiconductors and DC voltage sources that, when appropriately connected and controlled, can generate a multiple-step voltage waveform with variable and controllable frequency, phase and amplitude BIB002 . The staircase voltage waveform is synthesized by selecting different voltage levels generated by the proper connection of the load to the different DC voltage sources. This connection is performed by proper switching of the power semiconductors BIB003 . BIB002 Owing to the increased power rating, improved harmonic performance, reduced electromagnetic interference (EMI), lower stress on the power switches and reduced voltage derivatives ( dv/dt ) BIB002 , multilevel inverter has continually draws the industrial and academic attention as preferentially one of the leading electronic power conversion mechanism for high power, medium voltage applications BIB003 and renewable energy interface; such as in photovoltaic (PV)  , BIB004 , wind  and fuel cells  . Multilevel inverters have been widely applied to chemical, liquefied natural gas plants, water Manuscript received December 8, 2014; revised May 22, 2015. treatment plants, transportation system (hybrid-plug-in vehicle), power generation, transmission and distribution systems BIB002 . Intuitively, this is why researchers are spending much efforts trying to improve multilevel inverter through control simplification, reducing the number of DC sources and enhancing the total harmonic distortion (THD) of the output signal  . However, for any advantage there usually be a corresponding disadvantage, multilevel inverter is not an exceptional case as it employ higher number of electronic components compared to conventional two-level inverters, introduce complexity in control and DC link capacitor voltage imbalance BIB006 ,  . Some approaches are developed to reduce the number of switches BIB006 , eliminate DC link voltage imbalance BIB007 ,  and simplify the pulse width modulation control algorithms BIB005 . The operations, power ratings, efficiency and of course, applications of multilevel inverter depends majorly on its topology and the type of control algorithm used in its PWM controller BIB001 . The most commonly known multilevel inverter topology is BIB003 ,  ,  -  :  Neutral-point-clamped (Diode clamped) MLI  Flying capacitor (Capacitor clamped) MLI  Cascaded H-bridge MLI By combining these topologies with one another, hybrid inverter topologies have been developed. Similarly, by applying different DC voltage levels, an asymmetric hybrid inverter topology has equally been in achieved. Moreover, MLI control techniques which are based on fundamental and high switching frequency includes BIB003 :  Space vector control  Selective harmonic elimination  Space vector PWM  Sinusoidal PWM As the paper is structured, after this introductory part, Section II and III of this paper give detailed account on the topology and control techniques of MLI. Section IV presents some discussions on the results obtained from the simulation carried out, while the last section concludes the paper.