Cascaded H-bridge Multilevel Inverter Research Articles

Generation of Optimal Switching angle for Nine Level Cascaded H Bridge MLI Using Most valuable Player Algorithm

Distributed generation (DG) sources often interfaced with grid by a Cascaded H-bridge multilevel inverter with a remote D.C source. The interface inverter has to adapt voltage on the either side of the grid and DG source while it has a control of active and reactive power exchange. The inverter terminal voltage is maintained based on frequency switching technique. However, in applications like micro grids are based on quality of output voltage at the point of common coupling. The present paper discusses an optimal frequency switching methodology that generates optimal fringing angle based on an evolutionary computing technique while maintaining the voltage level at PCC with a reduced harmonic distortion. Efficacy of the proposed method is illustrated by simulating a 9-level cascaded H bridge in MATLAB environment

Design and Analyses of Multi-Carrier Pulse Width Modulation Techniques for Double Level Circuit Based Cascaded H-Bridge Multilevel Inverter

The paper introduces the cascaded H-Bridge multi-level inverter with single-phase arrangement connected series with full-bridge inverter and CHBMLI configuration integrated with Double level circuit is proposed to reduce the harmonic distortion to get high power quality. In the proposed configuration, a half-bridge inverter has been implemented to increase the output voltage waveform nearly twice as compared with the conventional Cascaded H-Bridge MLI. For high Power quality, the output voltage waveform with the reference of sinusoidal, the phase opposition disposition carrier arrangement has been utilized in PWM for producing gate pulse of switches. The high waveform of output voltage achieved with the less no of switches, less % THD distortion, less conduction and switching losses. The purposed symmetrical model of CHBMLI is successfully verified using MATLAB based on simulation with DLC configuration.

Generation of Optimal Switching Angle for Nine Level Cascaded H Bridge MLI Using Most Valuable Player Algorithm

Distributed generation (DG) sources often interfaced with grid by a Cascaded H-bridge multilevel inverter with a remote D.C source. The interface inverter has to adapt voltage on the either side of the grid and DG source while it has a control of active and reactive power exchange. The inverter terminal voltage is maintained based on frequency switching technique. However, in applications like micro grids are based on quality of output voltage at the point of common coupling. The present paper discusses an optimal frequency switching methodology that generates optimal fringing angle based on an evolutionary computing technique while maintaining the voltage level at PCC with a reduced harmonic distortion. Efficacy of the proposed method is illustrated by simulating a 9-level cascaded H bridge in MATLAB environment.

Modified Space Vector Modulation for Cascaded H-Bridge Multilevel Inverter with Open-Circuit Power Cells

In this research, a new space vector modulation control algorithm is proposed to increase the reliability of the cascaded H-bridge multilevel inverters in case of faulty situations, where one or several power cells do not function. Methods to detect faults ensure finding open-circuit module exactly, which is fast and easy to program. By giving a detailed analysis of the impact of the faulty power cells, optimal redundant level states are chosen such that highest possible output voltage can be achieved, while the balance of the three-phase line-to-line voltage is maintained and common-mode voltage is reduced. The proposed algorithm is generalized so that it can be applied to H-bridge inverters of any level. The validity of the method is verified by numerical simulations and experiment results with an 11-level cascaded H-bridge inverter.

Dynamic simulation of three-phase nine-level multilevel inverter with switching angles optimized using nature-inspired algorithm

This paper recommends the use of grasshopper optimization algorithm (GOA), a nature-inspired optimization algorithm, for optimizing switching-angle applied to cascaded H-bridge multilevel inverter (CHBMLI). Switching angles are selected based on the minimum value of the objective function formulated using the concept of selective harmonic minimization pulse width modulation (SHMPWM) technique. MATLAB/Simulink-PSIM dynamic co-simulation conducted on a 3-phase 9-level CHBMLI shows that the CHBMLI controlled using GOA derived switching-angle is able to respond to varying modulation index demand and synthesize an AC staircase output voltage waveform with the desired fundamental harmonic and minimized selected low-order harmonics. Compared to Newton Raphson (NR) technique, GOA is able to find optimum switching-angle solutions over a wider modulation index range. Compared to Genetic Algorithm (GA), GOA is able to find global minima with higher probability. The simulation results validate the performance of GOA for switching-angle calculation based on the concept of SHMPWM.

Analysis on three phase cascaded H-bridge multilevel inverter based on sinusoidal and third harmonic injected pulse width modulation via level shifted and phase shifted modulation technique

This work proposes a comparative analysis of sinusoidal and third harmonic injected reference signal modulation accompany with level-shifted PWM technique named as phase disposition (LSPD), phase opposition disposition (LSPOD), and alternate phase opposition disposition (LSAPOD) and phase-shifted PWM technique. Switching pulses from both reference signal and PWM technique have been fed into three phase eleven level cascaded H-bridge multilevel inverter (CHBMLI) fed on a resistive-inductive load with the modulation depth (MD) set to varied from 80% to 100%. For voltage source inverter, total harmonic distortion (THD) content is critical and must be within the allowable range. To prove the feasibility of the reference signal with carrier signal schemes, the entire simulation of the modulation techniques is established and conducted via the Simulink environment. According to the analyzed result, the performance is acceptable in terms of %THDV and %THDI values. Simulation analysis also indicates, at full modulation depth, due to higher fundamental output voltage component produces via the THIPWM modulation technique compared to the SPWM technique, this causes higher %THDV value.

A Review on harmonics elimination in real time for cascaded H-bridge multilevel inverter using particle swarm optimization

Renewable energy has a great importance for power generation as it does not use the fossils fuels. Energy generated from alternative energy sources are weather dependent. To generate a continuous power to meet the load requirements, Battery energy storage system are used. Power conversion process must be much efficient as possible to convert the DC stored energy into AC. This conversion process is usually done by the help of inverters. This paper gives the brief overview on three main categories of multilevel inverter like cascaded h-bridge, neutral point clamped and flying capacitor multilevel inverter and highlights their advantages which can also help the scholars to deeply explore the categories of multilevel inverter. Harmonic elimination is usually done by controlling the switching angles of the inverter. Among all the switching angles techniques, selective harmonic elimination pulse width modulation (SHEPWM) technique is widely used, that has also discussed in this paper. Furthermore, to eliminate the harmonics using SHEPWM, it has the set of nonlinear transcendental equations, these set of equations can be effieceintly solved by the optimization methods. The most efficient and reliable optimization method like particle swarm optimization has been discussed with multiple objective functions in this paper. This paper will help the scholars to understand the finest category of multilevel inverter for harmonic elimination in terms of efficiency and output quality.

Asynchronous Particle Swarm Optimization-Genetic Algorithm (APSO-GA) Based Selective Harmonic Elimination in a Cascaded H-Bridge Multilevel Inverter

In this article, a hybrid asynchronous particle swarm optimization-genetic algorithm (APSO-GA) is proposed for the removal of unwanted lower order harmonics in the cascaded H-bridge multilevel inverter (MLI). The APSO-GA is applicable to all levels of MLI. In the proposed method, ring topology based APSO is hybrid with GA. APSO is applied for exploration and GA is used for the exploitation of the best solutions. In this article, optimized switching angles are calculated using APSO-GA for seven-level and nine-level inverter, and results are compared with GA, PSO, APSO, bee algorithm (BA), differential evolution (DE), synchronous PSO, and teaching–learning-based optimization (TLBO). Simulation results show that APSO-GA can easily find feasible solutions particularly when the number of switching angles is high; however, the rest of all stuck at local minima due to less exploration capability. Also, the APSO-GA is less computational complex than GA, BA, TLBO, and DE algorithms. Experimentally, the performance of APSO-GA is validated on a single-phase seven-level inverter.

Multilevel Inverter Based Power Quality Enhancement Using Improved Immune Control Algorithm

ABSTRACT Multilevel inverters are currently the subject of extensive investigation and are used primarily for medium and high voltage distribution systems. The work presented in this paper provides a cost-effective and realistic solution to mitigate power quality (PQ) problems. A Cascaded H-Bridge multilevel inverter (CHB-MLI) has been configured as a shunt active power filter (SAPF). It is well reported that large-scale use of power electronics-based devices leads to several PQ problems such as poor power factor, unregulated dc voltage, harmonics, voltage regulation etc. In this paper, an improved immune feedback control algorithm is proposed and developed to mitigate PQ issues by predicting the weighted active component of load current and to generate reference current for the grid. Extensive MATLAB simulation and experimental work have been reported for validation on a single-phase system. A low prototype model is developed in the laboratory to study and compare the steady-state and dynamic results of the proposed controller with conventional Least Mean Square (LMS) and Immune algorithm.

A Novel Three-Phase Transformerless Cascaded Multilevel Inverter Topology for Grid-Connected Solar PV Applications

Nowadays, multilevel inverters (MLIs) are gaining huge popularity for high power transformerless PV applications. Among the traditional MLIs, the cascaded H-bridge (CHB) MLI accommodates lower voltage rated input dc sources, which reduce the voltage stress across the devices. However, the CHB MLI requires multiple PV sources as separate dc-link voltage sources, which create more paths for leakage currents. Therefore, it is a challenging task to deal with the leakage currents in the case of CHB MLIs. In this article, a novel three-phase transformerless inverter topology for grid-connected solar PV application is introduced. This proposed that the inverter topology has six switches per phase, and it has the combined advantages of dc-bypass and ac-bypass circuit configurations. A new modulation strategy is developed for the proposed topology; it is based on a sine triangle pulsewidth modulation technique combined with the dedicated logic functions. The gate pulses for all switches are provided by using these dedicated logic functions. The switching pulses obtained from the dedicated logic functions control all the inverter switches so that the variation of common-mode voltage (CMV) is constant during the inverter operation. This results in reduced leakage current throughout the operation of the inverter. The theoretical analysis, simulations, and experimental results are presented to validate the proposed topology concept for a 3-kVA grid-connected system. Both the simulation and experimental results show that the proposed solution can well attenuate the leakage current; all the results are presented in the article.

Comparative investigation of 15 Level and 17 level cascaded h-bridge MLI with cross h-bridge MLI fed permanent magnet synchronous motor

Multilevel inverters offers eminent solutions to high voltage high power applications due to the association of several devices in a series configuration. In this paper, a comparative investigation of both 15 and 17 level cascaded h-bridge multi level inverter with cross h-bridge fed permanent magnet synchronous motor are presented by appropriate simulations and mathematical analysis. Comparative analysis includes Inverter output voltage and current, number of switching devices, stator current and speed of PMSM and total harmonic distortion levels. Limitation of several switching devices, which can afford high voltage in the inverter is the major problems raised in this study. The advantage of this analysis is to figure out the appropriate inverter that can be used for real time application by considering the factors via. Harmonic distortion, output voltage, current, number of switching devices etc. Validation of the analysis is processed through matlab/simulink platform.

An improved method of model predictive current control for multilevel cascaded H-bridge inverters

Abstract Finite control set ModelPredictive control (FCS-MPC) with the principle of considering all voltage vectors to find the optimal voltage vector for multilevel inverter in a very small sampling cycle is hardly feasible because there is no modulation part, the implementation of optimizing common-mode voltage and switching number for the multilevel inverter should be performed in the cost function. To solve the above problem, this paper proposes an improved method of model predictive current control selecting 19 adjacent voltage vectors and using weighting coefficients for common-mode voltage elimination and switching optimization. By using a discrete-time model of the system to predict the future value of the current for the voltage vector in the previous sampling cycle and its 18 adjacent voltage vectors, the one that minimizes a cost function will be selected. Thus, in a multilevel inverter with any number of levels, the cost function is performed only 19 times in a sampling cycle. The computation on FPGA allows 19 calculations of the cost function to be performed in parallel, so the executing time is very small. The feasibility of the proposed algorithm is verified by simulation model on MATLAB-simulink software and the experimental 11-level cascaded H-bridge multilevel inverter model.

Performance improvement of cascaded H-bridge multilevel inverters with modified modulation scheme

This study proposes a modified modulation scheme based on the phase-shifted pulse-width modulation (PS-PWM) method to improve the output performance and reduce the switching loss in cascaded H-bridge multilevel inverters. The PS-PWM method is one of the most popular modulation schemes. However, it generates significant switching loss, which can lead to the failure of power semiconductor switches. Various studies have proposed modulation schemes to reduce switching loss. The clamped discontinuous PWM (DPWM) method achieves the best switching loss reduction performance in comparison with other modulation schemes. However, the clamped DPWM method has low output characteristics, such as total harmonic distortion. The proposed modulation scheme achieves the same switching loss reduction and improved output performance by modifying the dwell time order. The proposed evenly clamped DPWM method was compared with the conventional clamped DPWM method through simulations and experiments.

Performance analysis of SLMS based control for PV-STATCOM using a CHB-MLI

ABSTRACT Due to a phenomenal increase in non-linear/linear loads in the last two decades, power quality (PQ) has been a major concern nowadays. PQ issues and solutions for problems such as injection of harmonics by non-linear loads, voltage regulation, power factor correction etc. are current topics of research. So, harmonic mitigation using a Cascaded-H Bridge Multilevel Inverter (CHB-MLI) is the focus of this paper. In this paper, photovoltaic Static compensator (PV-STATCOM) is designed and simulated; its working is checked in two modes. In mode-I, both active and reactive power are supplied to the grid, which is performed during day time only. In mode-II, only reactive power is supplied to the grid, and this mode works during night time. Therefore, the proposed PV-STATCOM can be utilised to its full potential throughout the day. A new proposed adaptive control technique-Sigmoid Least mean square (SLMS) and PV feed-forward term are combined to generate reference currents. Phase shift pulse width modulation (PS-PWM) technique is implemented to generate the pulses. The complete system is simulated in both the modes under various load conditions. Hardware results for the developed five-level MLI prototype are also illustrated.

A Hybrid Nearest Level Combined With PWM Control Strategy: Analysis and Implementation on Cascaded H-Bridge Multilevel Inverter and its Fault Tolerant Topology

This paper presents a hybrid control strategy which combines the nearest level control technique with PWM control technique on a cascaded H-Bridge Multilevel Inverters (MLI). MLIs have become very popular due to its several advantages in the application areas like industrial drives and grid-connected renewable energy generation systems. With the reduced number of switches, driver circuits, conduction losses, switching losses, voltage stresses, size, and cost of the system, MLI has outperformed its two-level counterpart in terms of power quality issues. Reduction in the Harmonics and consequently the Total Harmonic Distortion (THD) in the output voltage has added to the benefits of MLI. Topological advancements in MLI require a satisfactory output voltage control strategy. In this work, a hybrid control strategy for a smooth and wider range of control of output voltage is proposed. The hybridized scheme enhances the control range of the voltage considerably. Moreover, the THD is also reduced compared to the conventional sinusoidal PWM scheme. A thorough analysis of the scheme has also been presented in the paper. SIMULINK/ MATLAB environment is used for testing the simulation model of the proposed control scheme. This hybridized controlling technique is also simulated for thermal modelling on PLECS software and power loss analysis is performed. The mathematical and simulation analyses are validated on an experimental prototype using a TMS320F28335 DSP controller card. The hybrid scheme has also been tested for a fault tolerant model of the cascaded H-bridge inverter. The performance of the hybrid scheme under different fault condition has also been shown to work satisfactorily.

A Single-Carrier-Based Pulse-Width Modulation Template for Cascaded H-Bridge Multilevel Inverters

Multiplicity of the triangular carrier signals is a criterion for the extension of sinusoidal pulse-width modulation, SPWM, to a number of output voltage levels per phase-leg in cascaded H-bridge (CHB) multilevel inverter (MLI). Considering medium and high voltage applications where appreciable number of output voltage levels from CHB MLI is needed, commensurate high number of carrier signals in either classical level- or phase-shifted SPWM scheme for this inverter is inevitable. High-quality output waveforms from CHB MLI system demands precise synchronization of these multi-carrier signals. Sampling issues, memory constraints and computational delays pose difficulties in achieving this synchronization for real-time digital implementation. This study presents a PWM template for CHB MLI. The developed control concept generates adequate modulation templates for CHB inverter wherein a sinusoidal modulating waveform is modified to fit in a single triangular carrier signal range. These templates can be used on CHB inverter of any level with no further control modification. Nearly even distribution of switching pulses, equal sharing of the overall real power among the constituting power switches and enhanced output voltage quality were achieved with the proposed modulation. For a 3-phase, 7-level CHB, simulation and experimental results, for an R-L load, were presented.

The review and investigation of sustainable 13 level multilevel inverter control strategies

This artefact deals with review and the comparative assessment of three different closed loop control approaches for cascaded H-bridge multilevel inverter (CHBMLI) fed 3 Φ induction motor. The sustainable solar energy has been efficiently used as input of the proposed MLI. The 12 IGBT switches have been used to achieve 13 levels for 1 Φ so 36 IGBT switches are utilised for 3 Φ inverter. The ANFIS, PID and fuzzy intelligent controllers are employed with feedback signals to get the optimum solution. The analysis of 13-level CHBMLI with ANFIS, fuzzy and PID controllers are designed. The performances are measured by using an open loop and closed loop environment with two compassionate speeds. The performances are % of THD, steady state error, settling time and peak time is measured and compared by using MATLAB-Simulink.

Analysis of Switching Losses in Multilevel Cascaded H-bridge and Diode-Clamped Inverter.

Analysis of Switching Losses in Multilevel Cascaded H-bridge and Diode-Clamped Inverter.

An effective PSO based cascaded H-bridge multilevel inverter STATCOM with reduced number of materials count

Medium voltage and high power multilevel inverters are nowadays widely used for reactive power compensation applications. Multilevel inverters based Static Synchronous Compensator (STATCOM) devices makes the power system more feasible due to the benefits offered by the multilevel inverters such as output voltage with lower harmonics, high modularity, and high-power quality in the output. This paper presented an effective Particle Swarm Optimization (PSO) algorithm based cascaded H-bridge multilevel inverter STATCOM with reduced number of materials count. The materials used for the semiconductor devices are the Insulated Gate Bipolar Transistors (IGBTs). These IGBTs are fired using the optimized switching angles, which further leads to minimum total harmonic distortion. PSO technique is being used for the calculation of optimized switching angles. Further, the performance of PSO based multilevel inverter with STATCOM is investigated by calculating the harmonics reduction and total harmonic distortion.

Artificial Neural Network and Newton Raphson (ANN-NR) Algorithm Based Selective Harmonic Elimination in Cascaded Multilevel Inverter for PV Applications

In this article, a hybrid Artificial Neural Network - Newton Raphson (ANN-NR) is introduced to mitigate the undesired lower-order harmonic content in the cascaded H-Bridge multilevel inverter for solar photovoltaic (PV). Harmonics are extracted by the excellent choice of opting switching angles by exploiting the Selective Harmonic Elimination (SHE) PWM technique accompanying a unified algorithm in order to optimize and reduce the Total Harmonic Distortion (THD). ANN is trained with optimum switching angles, and the estimates generated by the ANN are the initial guess for NR. In this study, the CHB-MLI is combined with a traditional boost converter, it boosts the PV voltage to a superior dc-link voltage Perturb and Observe (P&O) based Maximum Power Point Tracking (MPPT) algorithm is used for getting a stable output and efficient operation of solar PV. The proposed system is proved over an eleven-level H-bridge inverter, the work is carried out in MATLAB/Simulink environment, and the respective results are confirmed that the proposed technique is efficient, and offers an actual firing angles with a few iterations results in a better capability of confronting local optima values. The suggested algorithm is justified by the experimental development of eleven-level cascaded H-bridge inverter.