Cascaded Multilevel Inverter Research Articles

Implementation of Phase Shifted Carrier Modulation Technique for Cascaded Five-Level Inverter Using FPGA

This paper presents the development of Xilinx Field Programmable Gate Array (FPGA) to control single phase Cascaded Multilevel Inverter (MLI). FPGA realizes high speed switching and attains a high over sampling rate. The FPGA provide eight control signals for five level output voltage using Phase Shifted Carrier (PSC) modulation technique. All the function modules of the designed program was implemented using Very High Speed Integrated Circuit Hardware Description Language (VHDL) and Xilinx ISE 9.2i software was employed as a simulation and compiler tool. The proposed strategy can provide a wide range of rms output voltage by varying the modulation index. The simulation of the system was carried out by Matlab/Simulink. Simulation and experimental results are provided.

Artificial intelligent controller-based power quality improvement for microgrid integration of photovoltaic system using new cascade multilevel inverter

Nowadays, grid-connected photovoltaic (PV) power system is quite popular in many countries. For grid-connected PV power system, to achieve maximum power and good power quality of the system are considered as big challenges. In order to achieve this, artificial intelligent (AI) controller-based maximum power point tracking (MPPT) algorithm has been investigated for PV system as well as a new cascade multilevel inverter (MLI) is proposed for grid integration of PV system. The proposed cascade MLI has been designed with a smaller number of power electronic switches and it can be operated at asynchronous voltage sources, which is most adaptable for PV system. This proposed inverter can reduce the total harmonic distortion (THD) at output side by means of increasing the output voltage level with this power quality of the system has been improved. The microgrid integration of proposed inverter has been controlled by using AI-based voltage source controller and this proposed system is designed and simulated in MATLAB environment at various weather conditions and loading conditions. Finally, prototype model has been developed in laboratory and evaluating its performance. The simulation results and prototype results were verified with IEEE 1547 standard that proves the proposed system effectiveness.

Novel Reduced Switch-Count Structure for Symmetric/Asymmetric Cascaded Multilevel Inverter

In this paper, a novel Cascaded H-Bridge (CHB)-based multilevel inverter for symmetric/asymmetric configurations is presented. The proposed MLI can be utilized in medium-voltage applications such as electrical machine drives as well as grid connection of renewable energy resources. The proposed structure uses fewer count of semiconductor devices at the same voltage level in comparison with classic and advanced structures. Cascaded connection of the proposed basic cells leads to reduce complexity and increase efficiency of the proposed structure. In order to investigate the capability and superiority of the proposed structure, a comprehensive comparison is conducted between this structure and the advanced ones in terms of efficiency, switch and gate driver count, and total blocking voltage (TBV). The fundamental frequency switching method is employed to generate proper switching pulses. The performance of the proposed multilevel inverter is investigated by simulating in MATLAB/Simulink environment. The experimental implementation for proposed 15-level symmetric and 33-level asymmetric structures validates the correctness of simulation results.

Asymmetric hybrid multilevel inverter with reduced harmonic using hybrid modulation technique

<span>This paper studies the Asymmetric cascaded three phase multilevel inverter developed with hybrid modulation technique applied for an industrial application. The aim of this paper to reduce the Total harmonics distortion in the cascaded multi level inverter by introducing the new concept to develop the three phase CMLI. This inverter has two segments, one segment has H-bridge inverter and another segment has sequential arrangement of power semi conductor switches with asymmetrical voltage source in the ratio of 1:2. Similarly develop the segments for other phases. This new topology is called as Hybrid MLI. This hybrid MLI is used to reduce the no of semiconductor device requirement and the Total harmonics distortion. The inverter is controlled by Phase disposition (PD) and alternative phase opposition disposition PWM technique (APOD). This control technique is used to minimize the current harmonic and increase the system performance. The circuit is simulated using Matlab circuit and its performance is compared using PD and APOD PWM techniques and verified with simulation results.</span><p> </p>

Development of Cascaded Multilevel Inverter Based Active Power Filter With Reduced Transformers

Active power filter is a power electronic converter used for improving the quality of supply by eliminating the effect of harmonics due to non-linear loads. This paper recommends a concept for shunt active power filter (SAPF) using a single power source fed to a cascaded multilevel inverter (CMI) with 3-φ transformers. Apart from traditional transformer based topologies, the required number of transformers are substantially reduced, resulting in less space requirement, which leads to low cost and simple control system. The proposed CMI based SAPF has a capacity to compensate for contaminated load with high harmonic and a low power factor. The effective i d -i q theory is used to calculate compensation currents. DC link voltage regulator analyzed through delay time and controller gain. The tasks of the controller in the SAPF can perform all necessary actions for correct operation in SAPF. A wide range of computer simulation results demonstrated and validated the results with the prototype experimental setup.

Design and Experimental Investigation of Modified Switched Coupled Inductor Quasi Z-Source Cascaded Multilevel Inverter

This paper proposes Switched coupled inductor (SCL) based quasi-Z- Source cascaded multilevel inverter (qZS-CMI), (SCL qZS-CMI) using nearest level modulation (NLM) technique in this paper. The proposed inverter introduces appealing advantages over conventional qZS-CMI such as lower component voltage stress, improved output power quality and efficiency. Both simulation and experimental verification have been carried out for SCL qZS-CMI with a power rating of 250W to validate the above claims.

Operation and Control of a Grid-Connected Asymmetrical Cascaded Multilevel Inverter

This article presented a new structure for the grid-connected multilevel inverters (MLIs) circuit with the ability of the cascaded connection. The proposed inverter is capable of transformerless connection of distributed generation resources to the network. The control system manages the power injection to the grid by minimizing the output current harmonics as well as exchanging reactive power with the grid. The self-balancing state of the capacitors' voltage is occurred only with the switching technique without any measurement sensors. An enhanced phase-locked loop (EPLL) and a proportional resonant (PR) controller are employed for the proposed asymmetric MLI. An important feature of the proposed inverter is the ability of stable performance and fast dynamics of the control system to the changes of the reference values. Simulation and experimental results are presented in order to validate the performance accuracy of the proposed MLI.

Leakage Current Minimization Using NPC DC Decoupling Method for Three-Phase Cascaded Multilevel PV Inverter

This brief presents a new neutral point clamped (NPC) DC decoupling method based three-phase three-level cascaded multi-level inverter (CMLI) for the minimization of leakage current in PV systems. The proposed CMLI reduces the transitions in the terminal and common-mode voltage during common zero state. Therefore, a common zero state in all the three phases is identified and the value of terminal or common mode voltage is retained to its previous active state value using the clamping circuitry. This action results in reducing the number of transitions in the terminal voltage, which further helps in the minimization of leakage current. As a result, the size of EMI filters and common mode chokes required for the proposed CMLI are also reduced. Further, the mathematical analysis of terminal voltage using the switching function concept is also discussed in this brief. From the mathematical expression of terminal voltage, the analytical waveforms of terminal voltage for both conventional and proposed CMLIs are also shown in this brief. The presented switching function analysis is also supported using the simulation and experimental results presented in this brief. Complete details with respect to the operation, simulation and experimental results of the proposed CMLI are presented in this brief.

Mitigation of Harmonics for Eleven-Level Cascaded Multilevel Inverter using SPWM and SHE Techniques

Mitigation of Harmonics for Eleven-Level Cascaded Multilevel Inverter using SPWM and SHE Techniques

FPA Optimized Selective Harmonic Elimination in Symmetric–Asymmetric Reduced Switch Cascaded Multilevel Inverter

Symmetrical and asymmetrical multilevel inverters (MLIs) have demonstrated its usefulness in a wide range of applications. This is accomplished due to the ongoing improvement by reducing the converter size and enhancement in the voltage quality. In this article, a generalized cascaded MLI structure is developed, which can operate in both symmetric and asymmetric modes. Comparative assessment in terms of the number of components and voltage stress warrants the design superiority. A new selective harmonic elimination (SHE) control using flower pollination algorithm (FPA) is investigated for the developed asymmetrical MLI. The salient features of the FPA such as less burdensome compilation and ability tos single-stage local and global search ascertain the elimination of the targeted harmonics through optimum angles computation. Moreover, the competence of the FPA is verified by comparing it with well-known SHE algorithms. Simulation analysis is carried out in MATLAB/Simulink environment, which validates the workability of the developed system. Experimental tests using fundamental and high switching frequency control techniques are further conducted under a dynamic environment to demonstrate the efficacy of the proposed methodology.

Dual-T-Type Five-Level Cascaded Multilevel Inverter With Double Voltage Boosting Gain

The switched-capacitor-based cascaded multilevel inverters (CMI) have been emerging due to their voltage boosting capability. Unfortunately, they suffer from impulse charging current and nonuniform operation. This article presents a topology termed as dual-T-type five-level CMI to resolve these problems without compromising the desirable voltage boosting characteristic. The main idea is to integrate a half bridge and an inductor to soft charge a capacitor that is connected in series with the dc source. The capacitor enables the voltage gain boosted to two, while the control of eight power switches that constitutes a dual-T structure enables five voltage levels generation. In addition, uniform operation is achieved for cascaded extensions. The operating principle of the proposed topology is analyzed and elaborated. For validation, simulation, and experimental results of a prototype are presented.

New basic unit and cascaded multilevel inverters with reduced power electronic devices

ABSTRACT In this paper, a new cascade multilevel inverter based on series connection of several basic units is proposed. The basic topology consists of 5 dc voltage sources and 12 switches. The required mathematical analysis consisting of voltage on switches, power losses and the values of dc voltage sources is provided. To verify the advantages of proposed topology, the suggested structure is compared with other multilevel inverter topologies in terms of used dc voltage sources, switches, voltage on switches and the number of on-state switches. The proposed structure uses the least numbers of dc voltage sources and switches compared to other multilevel inverters for the same number of levels. Also, voltage rating on the switches in the proposed topology is less than other topologies. These characteristics cause the weight, size and cost of proposed topology to be reduced. The proposed inverter is implemented using experimental setup. The experimental results verify the performance of proposed structure.

Modular multilevel inverter for renewable energy applications

<p>This paper proposes a Multilevel Inverter (MLI) which focuses on two objective , minimal voltage sources and lesser switching component. The proposed Asymmetrical Cascaded Multilevel Inverter (ACMLI) is able to achieve the objective by selectively opting the voltage level of DC sources chosen and implementing the mathematical operation of addition and subtraction on the DC sources. This system also utilizes multiple carrier sinusoidal pulse width modulation technique (MCS-PWM) for operating the switches. It is found that the number of switches required for proposed modular bridge ACMLI and modified H bridge ACMLI was lesser than the traditional Cascaded H bridge Multilevel Inverter (CHB-MLI). It is also evident that the number of DC voltage sources and filter required for smoothing the output waveform is reduced compared to the traditional MLI. The Total Harmonic Distortion (THD) for the proposed circuit was simulated and analyzed in MATLAB Simulink environment and the results are found to be very less and satisfactory. The proposed circuit can find its application in integrating Renewable Energy Sources (RES) to the utility grid, Electrical Vehicle (EV) , harmonic reduction and so on. The simulation results of the proposed circuits are tabulated and compared with the traditional cascaded MLI.</p>

Reduction of Current Harmonics by Cascaded Multilevel Inverter based Shunt Active Power Filters

Majority of loads in use today are power electronics based non-linear devices. Despite being compact and providing low energy consumption these loads generate inherent harmonics. Harmonics have several adverse effects such as interference with the communication lines, incorrect meter readings, increased losses, increased heating of electrical and sensitive electronic equipment. Sophisticated power electronic converter based filters named as Shunt Active Power Filters (SAPF) are widely being employed that provide superior harmonic filtering capabilities. Basic objective of SAPF is to generate or absorb currents that compensate harmonic currents produced by non- linear loads. These currents should be opposite in phase but have equivalent magnitude as that of harmonic currents. As compared to Diode-Clamped and Flying capacitor multilevel inverters, Cascaded multilevel configuration is employed for many applications due to ease of control and simple structure. In this research paper, power quality in a three-phase three- wire system is improved by reducing source side current harmonics produced by a non-linear load. Initially a three-level Cascaded multilevel inverter based SAPF is developed and its performance is analyzed by using advanced Adaptive Neuro Fuzzy Inference System (ANFIS) controller. DC link capacitor voltage and percentage Total Harmonic Distortion (%THD) in source currents is measured at PCC for balanced loading conditions and results are compared. In this paper, it is also proposed to incorporate multilevel inverter topology concepts by employing Five-Level and Seven-Level Cascaded Multilevel Inverters as VSI circuit for SAPF. Performance of these multilevel Shunt Active power filters is analyzed by ANFIS controller. Instantaneous Active-Reactive power theory is implemented to compute reference compensating currents for all Shunt Active power filter models. Phase Disposition type Pulse Width modulation is chosen for generating gate pulses for VSI circuits of all Cascaded multilevel inverter configurations. Three-level, Five-level and Seven-level Shunt active power filter models are developed and simulated using MATLAB/ Simulink and results are presented.

A Three-Phase Hybrid Cascaded Multilevel Inverter with Multicarrier PWM technique

Multilevel voltage source inverter has drawn tremendous importance in the area of high power applications. This paper presents a three-phase modified hybrid cascaded multilevel inverter incorporating a standard three-leg inverter with H-bridge cells in series with each leg. The switching scheme with the multicarrier level shifted sinusoidal PWM is implemented to produce the five-level voltage at the output. Simulations have been performed using MATLAB to study voltage levels, modulation scheme, and THD. Finally, the possibilities of future works are addressed.

Design and Validation of a Generalized Multilevel Inverter with Simplified Switching Technique

—This paper proposes a generalized 3-phase cascaded multilevel inverter (CMLI) along with a simplified space vector pulse width modulation (SVPWM) based on 2-level inverter (2LI) topology. While conventional cascaded H-bridge inverters (CHBIs) call for a number of DC sources which increase the cost and complexity of their implementation, the proposed CMLI requires one DC source only. On the other hand, the complexity of SVPWM lies in the switching diagram that consists of a large number of triangles comprising uneven numbers of switching vectors. The generalized 3-phase CMLI proposed in this paper is aimed at reducing the number of switching vectors of each triangle. The hypothesis of the proposed CMLI-SVPWM is firstly illustrated through extensive simulation analysis using MATLAB/SIMULINK software. Feasibility of the proposed inverter is then validated through experimental measurements on a hardware prototype. Results reveal the superiority of the proposed inverter over existing ones in terms of the quality of the output voltage and current waveforms and the overall efficiency.

Multiple switching pattern for a modified reduce switch multilevel inverter: A comparison analysis

A primary concern of multilevel inverter is its capability to produce desired alternating voltage close to sinusoidal at the output, using multiple sources of DC voltage input. Mostly a multilevel inverter is used to generate the AC voltage from DC voltage. The aim of this paper is to investigate the output of 9 level multilevel inverter by modifying the conventional 5 levels H-bridge cascade multilevel inverter. The proposed design intending to reduce the number of switches from 16 switches to 10 switches. Implementation of different switching pattern methods; equal phase (EP), half equal phase (HEP), half height (HH) and feed forward (FF) and the related expression are presented in this paper. In the result section shows a different percentage of total harmonic distortion achieved. Out of all 4 methods, HH method suppressed distortion wave the most and resulted in the lowest THD in the proposed inverter. This paper shows that by reducing the number of switches in multilevel inverter structure maintains the same quality output as the conventional H-bridge topology. Furthermore, the manipulation of the switches firing angle contribute in decreasing the system THD.

Power Quality Improvement in Solar Fed Cascaded Multilevel Inverter With Output Voltage Regulation Techniques

The presence of harmonics in solar Photo Voltaic (PV) energy conversion system results in deterioration of power quality. To address such issue, this paper aims to investigate the elimination of harmonics in a solar fed cascaded fifteen level inverter with aid of Proportional Integral (PI), Artificial Neural Network (ANN) and Fuzzy Logic (FL) based controllers. Unlike other techniques, the proposed FLC based approach helps in obtaining reduced harmonic distortions that intend to an enhancement in power quality. In addition to the power quality improvement, this paper also proposed to provide output voltage regulation in terms of maintaining voltage and frequency at the inverter output end in compatible with the grid connection requirements. The simulations are performed in the MATLAB / Simulink environment for solar fed cascaded 15 level inverter incorporating PI, ANN and FL based controllers. To exhibit the proposed technique, a 3 kWp photovoltaic plant coupled to multilevel inverter is designed and hardware is demonstrated. All the three techniques are experimentally investigated with the measurement of power quality metrics along with establishing output voltage regulation.

Cascaded Multilevel Inverter for PV-Active Power Filter Combination into the Grid-Tied Solar System

The presence of non-linear loads (electronic power converter...) into the grid generally affects the electric power quality. This latter presents a fundamental factor in the grid consumers' performance. In addition, nowadays, the photovoltaic (PV) energy integration spreads for residential and commercial applications. These PV systems impose the use of power inverters to liaise with the electric grid. In this context, this power disorder fix is included in the list of PV inverter functions. That is recommended to guarantee better equipment performance. A MATLAB/Simulink simulation shows the electrical behavior of the whole model.

A Proposed Cascaded Multilevel Inverter with R-Load at Different Carrier Frequencies

Cascaded multilevel inverter has the major problem as voltage imbalance across the capacitors connected in circuits which are acting like dc sources. The number of level generation depends on the number of DC sources and switches placed in cascaded multilevel inverter topology. In this proposed topology the positive levels and zero levels of the inverter have been explained. This topology also work in symmetrical condition. The topology is simulated in MATLAB and its THDs are calculated at different modulation index. The voltage stress and loss calculations are carried out at different carrier frequencies.