Cascaded H-bridge Multilevel Inverter Research Articles

Improved performance with fractional order control for asymmetrical cascaded H-bridge multilevel inverter

This paper proposes a control scheme for seven level asymmetrical cascaded H-bridge multi level inverter (ACHBMLI) based on fractional order calculus. The seven level ACHBMLI consists of two H-bridges that are connected in series and are excited by different dc voltage sources. A simplified model is developed by assuming the small signal variation component is equal in both the H-bridges. A fractional order PID (FO-PID) controller is designed for the ACHBMLI using the simplified model. Simulation study shows the adequacy of FO-PID controller in giving an output voltage with minimum distortions. A conventional PID controller is also designed for ACHBMLI using the same simplified model. The performance of the ACHBMLI with FO-PID controller is compared with the performance of ACHBMLI with conventional PID controller. The simulation results prove the superiority of FO-PID controller in maintaining the output voltage of the ACHBMLI close to the reference voltage and in reducing the harmonic distortion of output voltage of the inverter. The simulation was done using MATLAB and the parameters of FO-PID controller was designed using FOMCON tool box.

Symmetrical DC-Link Capacitor Voltage for Multi Solar PV Array Fed CHBMLI in Standalone Application

In this paper, a generalized algorithm is proposed to balance the DC-link (DCL) voltage across each power cell of n number of cascaded H-bridge multilevel inverter (CHBMLI), using dc-dc converter, fed from multi solar photovoltaic (SPV) array for standalone application under varying environmental conditions, i.e. variation in radiation and temperature. Due to variation in the environmental conditions, the power flow through each H-bridge modules changes and subsequently the DCL voltage might change. This leads to unequal DC levels in the pole voltage of the CHBMLI, which results in different switching stress of the power modules. Therefore, the life span of the switches will get reduced. To maintain equal switching stress on each H-bridge module, duty cycle of the boost DC to DC converters is varied according to the proposed algorithm. It maintains equal voltage at the output of the boost converter under uniform/non-uniform environmental conditions. To operate the CHBMLI, the triangular carrier phase-shifted modulation has been used. The proposed algorithm as well as performance of the multi-SPV fed CHBMLI is simulated using PSCAD/EMTDC software for three-bridge seven-level CHBMLI. The experimental results are obtained using E4360 Modular Solar Array Simulator and Spartan 3AN FPGA controller for two-bridge five-level CHBMLI.

Asymmetrically Switched CHB Multilevel Inverters with Harmonic Mitigation Techniques Applied to Photovoltaic Power Generation

For the last few years, Multilevel Inverter (MLI) researchers have been motivated to reduce the component count in a significant manner by keeping the output level generation the same or increasing enough to be noticed. In this work asymmetrically switched Cascaded H Bridge (CHB) multilevel inverters with fundamental frequency switching are proposed for photovoltaic (PV) applications. Essentially different types of asymmetrically switched improved CHB topologies are discovered in brief and compared with necessary figures of merits including scaled versions. It is an approach to design different levels of voltages with the same number of switches and reduced device count. This paper reports different types of harmonic mitigation techniques, where the best switching angle optimizations are proposed to generate different levels. Moreover, the performance of the topologies is evaluated through THD minimizations by reducing the lower order harmonics. A few combinations of DC voltage sources are used from PV panels/batteries as input to the inverters for generating different output levels and THD is compared for different mitigation techniques. Theoretical calculation of THD is also shown and compared to simulation results for the proposed inverters. The proposed and simulated inverters are verified and tested though hardware in loop (HIL) implementation. As MLI needs compact filter requirements and better quality of output THD, this kind of proposed CHB inverters is suitable for medium and high power PV applications especially grid-tied PV inverters.

Optimal total harmonic distortion minimization in multilevel inverter using improved whale optimization algorithm

Abstract This paper presents the solution to mitigate the total harmonic distortion (THD) in multilevel inverters (MLIs) using novel improved whale optimization algorithm (IWOA). The IWOA falls under the category of swarm-based nature inspired optimization algorithms. It uses a novel diffusion process using a random walk technique and utilizes an additional ranking system to estimate the optimum solution to minimize THD. Moreover, THD minimization is further accomplished through nine various meta-heuristic algorithms for investigation and comparative analysis. The selected algorithms along with the proposed IWOA are rigorously tested on single phase 5 and 7 level cascaded H-Bridge MLIs for various performance parameters such as consistency, computational efficiency and speed of convergence. It is found that the proposed algorithm outperforms the nine algorithms and is efficient for THD minimization for modulation index (MI) in the range of 0–1. The results are analyzed and reported after thorough verification using MATLAB simulation.

Analysis and Control of PV Cascaded H-Bridge Multilevel Inverter With Failed Cells and Changing Meteorological Conditions

This article proposes an approach to control a photovoltaic cascaded H-bridge multilevel inverter with failed cells and changing meteorological conditions for large-scale grid-connected applications. The controller development is based on an analysis of the interaction between the inverter common-mode and differential-mode quantities, which is done in the time domain, supported by a space vector representation analysis. The proposed approach is able to produce balanced three-phase line-to-line voltages and currents even if there is a failed cell or if the fluctuating meteorological conditions cause uneven power distribution among the bridges. This is achieved through the modification of the pulsewidth modulation reference phase voltage angles combined to the injection of a dynamic homopolar component. Such an approach avoids tripping the system due to the protective functions #25 and #87 for per grid applicable codes and standards. Numerical simulations and laboratory experiments performed on a seven-level converter with different abnormal conditions to confirm the effectiveness of the suggested control strategy.

Modified Cascaded H-bridge Multilevel Inverter for Hybrid Renewable Energy Applications

Renewable energy sources and technologies have the potential to provide solutions to the long-standing energy problems being faced by developing countries. The renewable energy sources like wind energy, solar energy, geothermal energy, ocean energy, biomass energy and fuel cell technology can be used to overcome energy shortage in India. This paper proposes a modified multi-level inverter (MLI) topology for Hybrid Renewable Energy Sources (HRES) and a design of hybrid solar-wind power generation model with 9-level, 13-level and 17-level inverter topologies. A HRES connected to a modified Cascaded H-Bridge Multi Level Inverter (CHB-MLI) is developed, whose switches are controlled using Artificial Neural Network (ANN) model. The proposed hybrid energy system model consists of 10 Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) that intend to give 17 levels of output voltage. The proposed topology performs effectively with reduced number of components and reduced Total Harmonic Distortion (THD). The performance of the proposed system is analyzed by designing the model in MATLAB/SIMULINK environment. The simulation results of the proposed inverter for the HRES application are compared with the results of the existing topologies to show the effectiveness of the proposed model.

THIRTEEN LEVEL CASCADED H-BRIDGE MULTILEVEL INVERTER FED INDUCTION MOTOR DRIVE

Present day industrial applications require high power conversion for apparatus. For this power conversion multilevel inverter is used. The main purpose of using multilevel inverter is to produce high power output from the medium voltage source. The combination of several switches are present in multilevel inverter. It is the most efficient power converter which is suitable for high power applications with lesser number of harmonics. Because of having large number of semiconductor switches for higher level loads to larger size and increase price of the inverter. So in order to reduce this kind of drawback the cascaded H-bridge multilevel inverter is proposed with lesser number of switches. The proposed thirteen level cascaded H- bridge multilevel inverter output is shown in MATLAB/SIMULINK. The output of the multilevel inverter isfed induction motor and the speed, mechanical torque response are calculated. All the works are carried out through MATLAB/SIMULINK.

RETRACTED ARTICLE: Power flow control and power quality analysis in power distribution system using UPQC based cascaded multi-level inverter with predictive phase dispersion modulation method

Power quality is associated with the ability of utilities to provide electrical power without interruption. One of the major concerns in the electrical industry today is the issue of power quality over major loads. This work presents a Cascaded H-Bridge Multi-Level Inverter (CHBMLI) based unified power quality conditioner (UPQC) for the compensation of voltage sag/swell in the source side and current harmonics in the load side due to the non-linear loads. A predictive control based algorithm called as predictive phase dispersion modulation (PPDM) is used in the proposed system for the control of series and shunt active power filter of the UPQC. The shunt and series active power filter is connected back to back with a common DC link capacitor. The objectives of the proposed algorithm is to maintain a constant DC link voltage and to control the switching pulses of the CHBMLI according to the variations of the current in the load side and also the voltage unbalances in the source side. The performance of the UPQC is significantly improved with the proposed CHBMLI based UPQC than the conventional Voltage Source Inverters (VSI) based UPQC. The algorithm used in this work reduces the computational burden than the conventional model predictive controllers. The proposed CHBMLI based UPQC with PPDM technique is validated through simulation studies using MATLAB and a hardware prototype also realized and the results are investigated.

Multi-verse optimization algorithm- and salp swarm optimization algorithm-based optimization of multilevel inverters

Renewable energy sources are installed into both distribution and transmission grids more and more with the introduction of smart grid concept. Hence, efficient usage of cascaded H-bridge multilevel inverters (MLIs) for power control applications becomes vital for sustainable electricity. Conventionally, selective harmonic elimination equations need to be solved for obtaining optimum switching angles of MLIs. The objective of this study is to obtain switching angles for MLIs to minimize total harmonic distortion. This study contributes to the solution of this problem by utilizing two recently developed intelligent optimization algorithms: multi-verse optimization algorithm and salp swarm algorithm. Moreover, well-known particle swarm optimization is utilized for MLI optimization problem. Seven-level, 11-level and 15-level MLIs are used to minimize total harmonic distortions. Simulation results with different modulation indexes for seven-, 11- and 15-level MLIs are calculated and compared in terms of the accuracy and solution quality. Numerical calculations are verified by using MATLAB/Simulink-based models.

Design and implementation of cascaded H-Bridge multilevel inverter using FPGA with multiple carrier phase disposition modulation scheme

The paper deals with design of Cascaded H-Bridge Multilevel Inverter (CHB-MLI) with separate DC source to each inverter using multiple carrier Phase Disposition PWM such as symmetric disposition, phase opposition disposition and alternative phase opposition disposition to reduce the Total Harmonic Distortion (THD) and to improve the power quality of the supply voltage and current. In early days, the multilevel inverters are controlled with high frequency PWM method. This is not suitable for high power applications due to the high switching losses. With the help of multiple carrier PWM switching losses in the inverter circuit are reduced, so it can be used for high switchi ng frequency applications. The simulation of proposed system is developed using MATLAB Simulink software. The Performance simulation results are validated through experimental test setup using SPARTAN - 6 FPGA. Simulation results and effectiveness of the proposed method is proved and validated by experimental data.

RETRACTED ARTICLE: An ANN-based harmonic mitigation and power injection technique for solar-fed distributed generation system

In this article, a fifteen-level cascaded H-bridge multilevel inverter with active power filtering capability is suggested to increase the power quality in a single-phase distributed generation (DG) system. Integrating renewable power sources in the distribution line becomes easier with advancements in power electronic converters. At the same time, increase in usage of nonlinear loads leads to electronic pollutions like harmonics and power factor issues. Since most of the DG systems have interfacing inverters, it can be utilized for power quality improvement. This proposed work presents a control scheme to gain maximum utilization of these grid interfacing inverters with artificial neural network (ANN). An instantaneous p-q theory in a-s-0 reference frame-based control algorithm is derived to control the inverter in the single-phase distribution system. In the ANN-based approach, the control algorithm is solved and the ANN is trained based on the switching angles obtained. The trained system is integrated with DG system to operate as a multitasking circuit by adding active power filter (APF) operation. It is proposed to utilize the interfacing inverter as: (1) interfacing inverter to add power produced from renewable sources and (2) APF to mitigate the harmonics. Both functions are accomplished simultaneously. The proposed work is verified with extensive MATLAB/Simulink, and the obtained results demonstrate that the proposed approach delivers a notable improvement in power quality concerning reduction in total harmonic distortion and injection of real power generated through RES into the distribution line. A 3-kWp photovoltaic panel with multifunctioning inverter designed utilizing ANN is executed in an experimental setup to prove the efficiency of the proposed approach.

Improved Topology of Quasi - Z - Source Inverter and Its Grid-Connected Control

In order to solve the problems of low voltage boost capability, high capacitance voltage stress, narrow voltage boost range and small gain of traditional z-source inverters, a new topology structure of quasi-Z source cascade H-bridge multilevel inverters is proposed. The simulation was verified by MATLAB/SIMULINK software and compared with other Z source topologies. The results show that the new topology makes up for the problems of insufficient voltage boost capacity and narrow voltage boost range of the traditional Z source inverter, and the output power is high when the inverter is connected to the grid.

Minimization of total harmonic distortions of cascaded H-bridge multilevel inverter by utilizing bio inspired AI algorithm

Minimizing total harmonic distortion (THD) with less system complexity and computation time is a stringent constraint for many power systems. The multilevel inverter can have low THD when switching angles are selected at the fundamental frequency. For low-order harmonic minimization, selective harmonic elimination (SHE) is the most adopted and proficient technique but it involves the non-linear transcendental equations which are very difficult to solve analytically and numerically. This paper proposes a genetic algorithm (GA)-based optimization technique to minimize the THD of cascaded H-bridge multilevel inverter. The GA is the finest approach for solving such complex equations by obtaining optimized switching angles. The switching angles are calculated by the genetic algorithm by solving the nonlinear transcendental equations. This paper has modeled and simulated a five-level inverter in MATLAB Simulink. The THD comparison is carried out between step modulation method and optimization method. The results reveal that THD has been reduced from 17.88 to 16.74% while third and fifth harmonics have been reduced from 3.24%, 3.7% to 0.84% and 3.3%, respectively. The optimization method along with LC filter significantly improves the power quality providing a complete sinusoidal signal for varying load.

Fault Investigation in Cascaded H-Bridge Multilevel Inverter through Fast Fourier Transform and Artificial Neural Network Approach

In recent times, multilevel inverters are used as a high priority in many sizeable industrial drive applications. However, the reliability and performance of multilevel inverters are affected by the failure of power electronic switches. In this paper, the failure of power electronic switches of multilevel inverters is identified with the help of a high-performance diagnostic system during the open switch and low condition. Experimental and simulation analysis was carried out on five levels cascaded h-bridge multilevel inverter, and its output voltage waveforms were synthesized at different switch fault cases and different modulation index parameter values. Salient frequency-domain features of the output voltage signal were extracted using a Fast Fourier Transform decomposition technique. The real-time work of the proposed fault diagnostic system was implemented through the LabVIEW software. The Offline Artificial neural network was trained using the MATLAB software, and the overall system parameters were transferred to the LabVIEW real-time system. With the proposed method, it is possible to identify the individual faulty switch of multilevel inverters successfully.

Implementation of the conventional seven-level single-phase symmetrical cascaded h-bridge MLI based on PSIM

<span>Researchers<strong> </strong>have found interest in the multilevel inverters (MLI) owing to the low total harmonic distortion (THD) associated with their output voltage, as well as their low electromagnetic interference (EMI). The MLI represents an effective and feasible solution for enhancing power demand and minimizing AC waveforms’ harmonics as they generate a preferred level of output voltage as inputs from varying levels of DC voltages. In this paper, the performance of a seven-level cascaded H-bridge MLI with an asymmetrical number of power switches was evaluated. The simulation performance is shown to validate the operating principle of the single-phase cascaded H-bridge inverter. To control the MLI, a pulse width modulation approach was utilized. The operating principle of the MLI was verified via simulation using PSIM software.</span>

하이퍼튜브 추진용 케스케이디드 H-브리지 멀티레벨 인버터 설계

하이퍼튜브 추진용 케스케이디드 H-브리지 멀티레벨 인버터 설계

Enhancing the Performance of Multilevel Inverters using Modified SVPWM Techniques

In this paper, two types seven-level multilevel inverters in three phase configuration, Cascaded H-bridge Multilevel Inverter (CMLI) and Diode Clamped Multilevel Inverter (DCMLI) are simulated and compared the results for three different carrier PWM techniques. Here, Carrier based Sinusoidal Pulse Width Modulation (SPWM), Third Harmonic Injected Pulse Width Modulation (THIPWM) and Modified Carrier-Based Space Vector Pulse Width Modulation (SVPWM) are used as modulation strategies. These modulation strategies include Phase Disposition technique (PD), Phase Opposition Disposition technique (POD), and Alternate Phase Opposition Disposition technique (APOD). In all the modulation strategies, triangular carrier and trapezoidal triangular carrier signals are compared with reference signal for generation of control pulses. The simulations have been carried out for seven-level CMLI and DCMLI using MATLAB/Simulink. The detailed analysis of results in terms of %THD and utilization of DC-link voltage has been presented in this paper. By increasing the performance of inverters the utilization of input energy is reduced, then the corresponding energy sources can be reduced.

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>

A Symmetrical Multilevel Inverter Topology with Minimal Switch Count and Total Harmonic Distortion

A multilevel inverter (MLI) with reduced number of power devices, especially for the higher output levels, is presented in this paper. The generalized topology for ([Formula: see text]) level MLI is developed with symmetrical isolated dc sources and ([Formula: see text]) number of switches. A five-level MLI is developed with five power switches and then by adding each one additional switch two more levels are added in the output voltage waveform. With the help of lookup table, the working principle of the proposed five-level MLI topology is explained. Sinusoidal pulse width modulation–phase disposition control technique has been used to get a minimal total harmonic distortion (THD). The proposed MLI topology is simulated on the MATLAB platform. The laboratory prototype is developed for five-level MLI, and the experimental results obtained validate the simulation studies. The dSPACE 1104 is used for generating gate pulses in case of experimentation. The output voltage and current THDs obtained are 9.20% and 4.60%, respectively; the harmonics are mitigated more with five-level inverter. The proposed topology is compared with the cascaded H-bridge multilevel inverter.

Computational intelligence based control of cascaded H-bridge multilevel inverter for shunt active power filter application

This work proposes computational intelligence based control of five-level cascaded H-bridge inverter (5LCHB) for an application of shunt active power filter (SAPF) to reduce total harmonic distortion (THD) in supply current under nonlinear loads. Active and reactive power (PQ) method is used to extract reference currents. The proposed controller is effectively verified for three different carrier based pulse width modulation methods such as phase disposition (PD), phase opposition disposition (POD) and alternate phase opposition disposition (APOD). The required rules for fuzzy logic controller (FLC) are set by human brain computation. The performance of computational intelligence based FLC is implemented and is verified for reduction of THD under nonlinear loads. The DC voltage balance is achieved using the proposed controller. The proposed work is carried out in the environment of Matlab Simulink. The comparative performance analysis of THD in source current, individual harmonics (5th, 7th, 11th, and 13th), power factor (PF), real power, and reactive power compensation (RPC) for APOD, POD and PD using both PI and FLC are presented.