Control Of Multilevel Inverter Research Articles

An improved modulation technique suitable for a three level flying capacitor multilevel inverter

This research paper introduces an innovative modulation technique for controlling a 3-level flying capacitor multilevel inverter (FCMLI), aiming to streamline the modulation process in contrast to conventional methods. The proposed simplified modulation technique paves the way for more straightforward and efficient control of multilevel inverters, enabling their widespread adoption and integration into modern power electronic systems. Through the amalgamation of sinusoidal pulse width modulation (SPWM) with a high-frequency square wave pulse, this controlling technique attains energy equilibrium across the coupling capacitor. The modulation scheme incorporates a simplified switching pattern and a decreased count of voltage references, thereby simplifying the control algorithm.

Harmonics mitigation technique for asymmetrical multilevel inverter fed by photovoltaic sources

A multilevel inverter is an electrical device that converts a DC voltage into a higher AC voltage by generating a stepped waveform with several voltage levels. Unlike traditional inverters that produce a square wave or a pulse-width modulated (PWM) waveform with only two voltage levels, multilevel inverters can generate waveforms with three or more levels, resulting in reduced harmonic distortion, improved efficiency, and decreased electromagnetic interference. The design and control of multilevel inverters are active research areas that aim to enhance their performance, reliability, and scalability. In this research, a 31-level asymmetric cascaded multilevel inverter is suggested. The proposed multilevel inverter (MLI) system employs four photovoltaic cells as dc sources with structure of (1:2:4:8) Vdc. The system is modeled by MATLAB/Simulink and total harmonic distortion (THD) values of the output voltage and current are 1.106% for resistive load, and 1.35% and 0.403% for inductive load. These outcomes demonstrate the recommended circuit's efficacy and demonstrate its suitability for medium- and high-power applications.

Design and development of photovoltaic solar system based single phase seven level inverter

For solar photovoltaic (PV) systems, an upgraded triple gain seven-level inverter that works both independently and while connected to the grid is proposed. The two-stage configuration of the system is boost cascaded. The first stage has a one switch improved gain converter (OSIGC) to increase and normalize the input direct current (DC) voltage, and the second stage includes a unique seven level alternating current (AC) is produced via a multilevel inverter (MLI) design with triple voltage gain. The proposed OSIGC is appropriate for a broad range of conversions. The voltage gain in MLI was achieved using switched capacitor techniques. The DC-DC converter can achieve a maximum voltage gain of twelve and the MLI can achieve a maximum voltage gain of three, resulting in a DC-DC-AC voltage that can reach 36. Maximum power point tracking (MPPT) technique based on modified perturb and observe (PO) is used in OSIGC to maximise PV module power utilisation, and MLI control utilises sinusoidal pulse width modulation (SPWM) realistically. For the purpose of analysing the suggested system, a 200 Watt prototype statel is created. With a total harmonic distortion (THD) of 0.181%, up to 92.12% of the converter system’s overall efficiency is possible.

Medium-Voltage Drives (MVD) - Performance Analysis of Seven-Level Cascaded H-Bridge Multilevel Driver

The drawbacks of traditional inverters, particularly in high-power applications and medium voltage, have been highlighted in previous investigations. Due to the cascaded H-bridge multilevel driver (CHBMD) harmonic characteristics improved and power enhanced, inverters with multiple levels are increasingly popular for high-power applications. The scientific literature has documented works on multilevel inverter topologies, control strategies, and applications. Additionally, no conclusive results investigate or rate a three-phase multilevel inverter's effectiveness. The present investigation evaluates the performance of a multi-carrier sinusoidal pulse width modification (MCS-PWM) based, Seven-Level cascaded H-bridge multilevel driver (7LCHBMD). Performance assessments develop based on the outcomes of a modeling experiment on the CHBMD functionality utilizing MATLAB. The characteristics of the results chosen to perform the task were the harmonic range, waveform arrangement, and essential significance reducing the THD output of the 7LCHBMD. The MCS-PWM technique procedure from the perspective of the voltage line had been determined according to the findings of the simulation investigation and analysis carried out for the 7LCHBMD utilizing the PD-PWM as the control framework.

PI Controller and Space Vector Modulation based Direct Torque Control of Multi-level Inverter fed Induction Motor

Managing speed and Torque in various applications can raise the AC motor's efficiency and significantly save energy. Direct Torque Control (DTC) is significant among the several methods used to regulate AC motors. It is well known that the DTC of AC motors has very favorable control performance and implementation qualities. The control strategy uses the stator flux field orientation to control Torque and flux. DTC makes it possible to manage speed and Torque over a huge range. With a squirrel-cage induction motor model, a cascaded H bridge multi-level inverter, and a PI controller, this work makes an effort to examine and analyze the characteristics and operating principle of the DTC scheme. MATLAB/SIMULINK simulation results have been used to validate the efficacy and viability of this regulating strategy.

Model-Predictive Control of Multilevel Inverters: Challenges, Recent Advances, and Trends

Model predictive control (MPC) has emerged as a promising control method in power electronics, particularly for multi-objective control problems such as multilevel inverter (MLI) applications. Over the past two decades, improving the performance of MPC and tackling its technical challenges such as computational load, modeling accuracy, cost function design and weighting factors selection have attracted great interest in power electronics. This article aims to discuss the current state of MPC strategies for MLI applications, describing the significance of each challenge with the reported effective solutions. Through this review, the MPC methods are categorized into two groups, direct MPC (without modulator) and indirect MPC (with modulator). The recent advances of each category are presented and analyzed, focusing on direct MPC as the most applied method for MLI topologies. In addition, some of the important concepts are experimentally validated through a case study and compared under the same operating conditions to evaluate the performance and highlight their features. Finally, the future trends of MPC for MLI applications are discussed based on the current state and reported developments.

A Robust Control for Five-level Inverter Based on Integral Sliding Mode Control

The limitations of classical carrier wave-based pulse width modulation (PWM) techniques prevent themfromensuringgoodoutputqualityformulti-levelinverters.Thispaperproposesanewslidingmodecontrol(NSMC)method for controlling cascaded H-bridge multi-level inverters (CHB-MLIs) to improve the output quality of theinverter, reduce the common-mode (CM) voltage with high-order harmonics, and achieve stable and robustnesscontrolfortheCHB-MLIs.TheNSMCmethodmodulatesthePWMpulsesforthemulti-levelinverterbycomparingthecontrolsignalu(t)andthecomparatorlevelswithoutusingcarrierwavetechniques.Thisapproachfacilitatestheformation of a control signal u(t) which can be flexibly adjusted to optimize the generation of PWM pulses. Toreducethechatteringproblemaroundthesliding-modesurfaceathighfrequenciesandtoincreasespeedconvergence, the integral sliding-mode surface integrated with a continuous control law is used to design thecontroller. Additionally, a first-order low-pass filter (LPF) with a variable cut-off frequency is added to the controllawtoimprovestabilityandreduceoscillationcausedbyrapidandlargechangesintheloadcurrentamplitude.ThestabilityofthecontrolsystemisvalidatedbytheLyapunovtheory.Simulationandexperimentaltestswereperformedon the same cascaded H-bridge five-level inverter (CHB-5LI) with an R-L load. The results show that the proposedNSMC method is robust and performs better efficiently for multi-level inverter control systems. Furthermore, theoutput quality of the inverter is significantly improved compared to classical carrier wave-based PWM techniques,with a reduced CM voltage and fewer high-order harmonics, resulting in reduced losses and switching frequency. Therefore, the stability and strong robustness of the CHB-MLIs can b eachieved by the proposed NSMC method.

Design and control of bypass diode multilevel inverter using a single DC source

Design and control of bypass diode multilevel inverter using a single DC source

Load Voltage Control of a Wind Turbine-driven Three-phase Squirrel-Cage Induction Generator in an Islanded Microgrid

The intermittent nature of the wind resources and reactive power consumptions are major issues associated with squirrel cage induction generator wind power system when operated in an island microgrid mode. The resultant effect of these two issues are continuous fluctuations of load voltage which has adverse effects on electrical devices. This paper proposes a voltage regulation technique based on proportional controller and phase deposition sine pulse width modulation (PDSPWM) for the control of 5-level neutral point clamped multilevel inverter. The instantaneous voltage tracking strategy based on root mean square value of microgrid voltage was adopted to regulate and maintain the output load voltage at 400 𝑉𝑟𝑚𝑠 despite rotor fluctuations with wind speeds. The simulation was carried out in a MATLAB/SIMULINK environment and the performance of the control scheme was found to be excellent.

Real-Time Harmonic Optimization in Multilevel Inverter Using Artificial Neural Network (ANN)

Multilevel inverters (MLIs) are increasingly used in real time applications. Among several pulse width modulation (PMW) techniques currently deployed for the control of MLIs, selective harmonic elimination PWM (SHEPWM) technique arguably gives the best performance due to its direct harmonic mitigation capability. However, real time application of SHEPWM technique is presently infeasible due to the heavy computational cost involved in solving the transcendental nonlinear equations known as selective harmonic elimination (SHE) equations, which characterize the harmonics that are selected for elimination or mitigation. This paper presents a twostage approach to the online generation of switching angles that mitigate selected lower-order harmonics in multilevel inverters. The first stage involves an offline solution of SHE equations using ant colony optimisation (ACO). In the second stage, ACO computed results are used to train an artificial neural network (ANN) predictive model. The results obtained from the simulation of the proposed method in MATLAB/SIMULINK environment show that the method is highly efficient and accurate.

Grey wolf optimization-recurrent neural network based maximum power point tracking for photovoltaic application

To increase the photovoltaic (PV) power-generation conversion, MPPT is the primary concern. This works explains about the grey wolf optimization (GWO - RNN)-based hybrid maximum power point tracking (MPPT) method to get quick and maximum photovoltaic (PV) power with zero oscillation tracking. The GWO – RNN based MPPT method doesn’t need additional sensor for measuring irradiance and temperature variables. The NLT is used for the multi-level inverter (MLI) control strategy to achieve less harmonics distraction and less switching losses with better voltage and current profile. This employed methodology brings remarkable aspects in the PV boosting potential extraction. A GWO – RNN controlled LUO converter is a zero output harmonic agreement impedance matching interface that is MPPT is performed by placing the PV modules between the load regulator power circuit and the load regulator power circuit. To actualize the proposed hybrid GWO – RNN model for the PV system, perturb and observe, RNN, ant colony optimization, and artificial bee colony MPPT techniques are employed. The MATLAB interfaced dSPACE interface is used to finish the hands-on validation of the intended grid-integrated PV system. The obtained results eloquently support the appropriate design of higher-performance control algorithms.

A fault-tolerant reconfiguration system based on pilot switch for grid-connected inverters

The multi-level inverter has been widely applied in high-power applications, especially in grid-connected systems. In addition to some of the benefits provided by the multi-level inverter, it has the disadvantage to be more prone to failure because of the large number of components used. Therefore, fault-tolerant control of multi-level inverters is critical to ensure the stability and reliability of the system. This paper introduces a fault-tolerant reconfiguration system (FTRS) based on pilot switch for grid-connected inverters. FTRS includes the grid-connected inverter using pilot switches and a fault-tolerant modulation algorithm. FTRS aims to reduce the damage of insulated gate bipolar transistor (IGBT) failure of cascaded H-bridge (CHB) inverter and meet such application requirements as grid-connected systems. The grid-connected inverter using pilot switches and its modulation algorithm can complete fault isolation without the redundant backup H-bridge and can make H-bridge reconfiguration after the system receives the fault signal so that the healthy H-bridge will keep working with voltage peak. Reliability evaluation and comparison of the FTRS and other inverters are presented. The validation of the proposed method is confirmed by simulation and experiment results on the five-level grid-connecter inverter.

Improved power quality operation of symmetrical and asymmetrical multilevel inverter using invasive weed optimization technique

Low switching frequency pulse width modulation (PWM) technique for modulation and control of multilevel inverter in medium voltage high power applications is preferred in order to reduce the switching losses. In this context, a multilevel inverter operated with Selective harmonics minimization PWM technique offers better quality waveform at reduced switching losses. After the Fourier series analysis, the system of non-linear simultaneous transcendental equations is obtained. These equations are then solved to obtain switching angles to have certain low order harmonics at minimum value and regulation in the fundamental voltage magnitude. In this paper, a novel invasive weed optimization (IWO) technique is proposed to compute switching angles. The proposed technique can compute switching angles for both symmetrical and asymmetrical multilevel inverters. Thus it has superiority over well-known optimization techniques such as GA, PSO, DE, and ACO, etc. Moreover, in certain modulation index ranges, it provides faster convergence and accurate results which have been demonstrated in the paper. The computational results have been verified with the experimental result on the prototype developed in the laboratory. The field programming gate arrays (FPGA) based controller is used to implement the proposed technique. The hardware results have been found in close agreement with the computed results.

Analysis of Hybrid Solar Wind Energy System with Multilevel Inverter Control at the Load End

Integrating all energy supplies to the dc bus requires the use of power electronic devices. The effectiveness of a MLI with two variable generating units has been researched, and the performance has been enhanced through designed regulation. This paper discusses the system was processed to develop a three-phase voltage output, a magnitude of nearly 230 V at the Multi - level inverter side and a smooth waveform at the load side. The framework becomes more dependable after it is integrated with the grid.

Vector Control and Modeling of Modular Multilevel High Voltage Converter for Rail Vehicle Traction

Rail transit plays an important role in the social and economic life of China and even all countries in the world, especially some populous countries or regions. The traction drive system of rail vehicle provides three-phase AC with adjustable voltage and frequency for the traction motor, controls the speed and torque of the traction motor, and then controls the operation of the vehicle. The modular multilevel converter has the advantages of low harmonic, good power quality of output waveform, high reliability, no input filtering and power compensation, and is suitable in the field of frequency conversion. In this work, the open-loop scalar control and vector closed-loop control of modular multi-level high-voltage inverter were adopted. It was found that driven by modular multi-level variable frequency vector control system, asynchronous motor not only has less harmonic content of voltage and current waveform, but also its speed regulation characteristics have been improved.

An Extensive Review on Fault Detection and Fault-tolerant Control of Multilevel Inverter with Applications

An Extensive Review on Fault Detection and Fault-tolerant Control of Multilevel Inverter with Applications

Multi-carrier switching strategy for high-bandwidth potential balancing control of multilevel inverters

<span lang="EN-US">This paper confers on investigation of a direct torque control (DTC) of induction motor drive by 3 level neutral point clamp (NPC) multilevel inverter. The imbalance problem may deteriorate the electric drive performances which might cause a short circuit condition. Various balancing control strategies were proposed, however, most of them employed complex space vector modulation (SVM) and hysteresis-based controller that generates variable switching frequencies. The proposed method will offer a reliable balancing control strategy with a constant switching frequency, and moreover, it will provide excellent electric drive performances. This research proposed a new multi carrier switching modulation strategy that establish a high-band-width control for neutral point potential in the NPC inverter. Potency of the proposed high-bandwidth potential balancing strategy is validated through the MATLAB/SIMULINK environment.</span>

Closed Loop V/f Speed Control of Multilevel Inverter Fed Induction Motors Using PID and Fuzzy Logic Controllers

The Volts per Hertz (V/f) speed control method makes induction motors available to be used in variable speed applications. However, the great harmonic distortion in supply voltage is a major issue of this method. Therefore, this study focuses on decreasing the harmonic distortion in the supply to induction motors. For that, the use of thirty-one-level multilevel inverters (MLIs) is investigated. Another drawback of the V/f speed control method is the use of proportional-integral-derivative (PID) controllers as speed controllers, which are difficult to be tuned precisely. To overcome this, the use of fuzzy logic controllers is investigated. The whole model is developed and simulated in MATLAB/SIMULINK by varying two variables, i.e., reference speed and load torque, one at a time using each controller. The observations for the changes in speed, torque, stator current, and supply voltage to the induction motors are made. The system’s performance using fuzzy logic controllers is found superior.

Multicarrier PWM Based Control of Modular Multilevel Inverter with Grid Connected Solar PV System

In this work, a new modular multilevel inverter topology is introduced for a single phase grid connected Photovoltaic system. This multilevel inverter use less number of switches to generate seven levels compared to other conventional multilevel inverters. This requires only one isolated dc source to operate. So it is suitable for renewable energy application. This inverter is designed by submodule configuration; each sub module contains two switches and one DC link capacitor. The sub modules will be added to the inverter depending on number of levels. The voltage balancing of DC link capacitor is carried out by Y matrix PWM technique. Because of Y matrix PWM technique, the inverter gets a self capacitor voltage balancing ability. So there is no need of external devices required for balancing the voltage of capacitor. A PLL for grid integration and LCL filter are designed and integrated with this inverter. The simulation of proposed system is carried out by MATLAB/SIMULINK and performance of THD is monitored as per standards

Realization and Control Of Multilevel Inverter With GSA Tuned Pi Controller

Realization and Control Of Multilevel Inverter With GSA Tuned Pi Controller