Cascaded H-bridge Multilevel Inverter Research Articles

Comprehensive Analysis of Faults and Diagnosis Techniques in Cascaded Multi-Level Inverters

Reliability is a crucial factor to consider for multi-level inverters (MLIs) used in industrial applications. With the increasing number of power semiconductor devices, the potential for defects to significantly degrade the overall system is heightened. A highly effective fault-detection technique is required to minimize the impact of faults. This paper provides a comprehensive overview of the fundamental principles of multi-level inverters and the various sorts of faults that can occur in multi-level inverters. This study provides a comprehensive analysis of five-level cascaded H-bridge multilevel inverters (MLIs) under both normal and defective conditions. The paper outlines a fault-detection method that utilizes total harmonic distortion and a normalized output voltage factor. In addition, the paper discusses a fault-isolation strategy that relies on reducing amplitude modulation. This method leads to the development of a fault-tolerant inverter. The utilization of level-shifted pulse-width modulation (LSPWM) technology is employed for the purpose of switching operations. LSPWM is the most appropriate technique for MLIs that require a low amount of computational resources. The fault-diagnosis approach given is suitable for MLI-based drives, grid-connected operations, and other applications. This paper presents a comprehensive examination of the 5L-CMLI (5-Level Cascaded Multi-Level Inverter) under various fault scenarios in CMLI. Subsequently, various fault diagnosis approaches will be examined, including their advantages and disadvantages. The paper discusses several defects that can occur in the Insulated Gate Bipolar Transistor (IGBT) of a Current Mode Logic Inverter (CMLI), and also presents a design for a reliable fault diagnosis system. Furthermore, this analysis examines several fault detection strategies in CMLI, categorized according to open-loop and closed-loop dynamic systems fault classifications.

Analysis of Cascaded H Bridge Multilevel Inverter for Three-Phase Induction Motor Drive

The last ten years have seen a rise in the usage of multilayer inverters. Because they can produce waveforms with a greater harmonic spectrum and reliable output. Several high voltages and high-power applications are suitable for these new inverters. A multilayer converter not only produce high power ratings, but it also saves time and money and enhances the system performance in terms of harmonics, dv/dt strains, and pressures on the motor bearings. Owing to its flexibility and modularity, the possible topology for a power application is the cascaded H-bridge multilevel inverter (CMI) with separated DC sources. This study investigates a cascade H bridge multilevel inverter, such as a Three, Five, Seven, Nine and Eleven level inverter in order to drive a three phase AC induction motor. A Level shifted Pulse Width Modulation (LSPWM) technique was applied for the CHBMLI. Specific emphasis is given to aspects like modulation and total harmonic distortion that are preferable or necessary for multi-level converters. For both intellectual and scientific considerations, investigating sine triangle carrier pulse width modulation is deemed to be the most auspicious approach. Analysis of the many performance parameters, including load torque, motor speed, and efficiency, an extensive survey is conducted. MATLAB / Simulink is built into the entire system, and simulation results are developed. The purpose of this research is to demonstrate the performance of 9-level and 11-level fed induction motor driving results for Electric Vehicle applications. CHBMLI fed motor drive is better suitable for Induction Motor Drives.

A Novel NR-DA-Based ANN for SHEPWM in Cascaded Multilevel Inverters for Renewable Energy Applications

Harmonics is the major power quality problem caused by nonlinear devices, leading to malfunction or operational halt of the system. Low-order harmonics increase vibration and heat generation in motors. Therefore, controlling harmonics in the output waveform is the prime target for industrial applications to avoid economic loss. Selective harmonic elimination pulse width modulation (SHEPWM) is one of the techniques used for eliminating or minimizing selected harmonics in the output voltage waveform. This paper utilizes the Newton-Raphson method and Dragonfly Algorithms to calculate optimum switching angles for a Cascaded H-bridge Multilevel inverter (CHBMLI). The algorithms use non-linear equations to calculate the Switching Angles of MLI. The Dragonfly algorithm requires several iterations to reach an optimum solution. For complex problems, this algorithm becomes computationally expensive and time-consuming. A lookup table addresses the limitation by offline training an Artificial Neural Network (ANN) to generate the optimum switching angle for a given modulation index. Neural Fitting Tool in MATLAB software is used to train the ANN model. The simulation is performed using MATLAB SIMULINK software for both 5-level and 7-level CHBMLI configuration. The Dragonfly algorithm-based ANN achieves THD 8.84% when the modulation index (M) equals 0.8 for a 7-level inverter and THD 14.91% for a 5-level inverter and effectively minimizes third and fifth-order harmonics.

Evaluation of a multiphase cascaded H-bridge inverter for induction motor operation

Multi-phase systems are becoming more popular for applications requiring high power and precise motor control, even if single-phase AC power is still frequently utilized in households and some enterprises. While both systems have benefits over single-phase, there are trade-offs associated with each. Because of its balanced operation and effective power transfer, the three-phase (3-Φ) system is the most widely used multi-phase system. Nevertheless, different phase values can be investigated for particular applications where reducing torque ripple and harmonic content is essential. Using odd numbers of phases (such as 5-Φ) that are not multiples of three is one method. This design has the ability to reduce torque ripple by producing a more balanced magnetic field as compared with even-numbered phases. But adding more phases also makes the system design and control circuitry more complex. Systems with five phases (5-Φ) provide a compromise between performance and complexity. Applications such as electric ship propulsion, rocket satellites, and traction systems may benefit from their use. Nevertheless, choosing a multi-phase system necessitates carefully weighing the requirements unique to each application, taking into account elements like cost, power transmission, control complexity, and efficiency. The increasing popularity of electric vehicles and renewable energy technologies has led to the need for inverters in current electric applications. Conventional inverters provide square wave outputs, which cause the drive system to become noisy and cause harmonics. Multi-phase multilevel inverters can be used to enhance inverter functioning and produce an improved sinusoidal output. This study focuses on an induction motor drive powered by a five-phase multilevel cascaded H-Bridge inverter. With less torque and current ripples in the motor rotor, the power conversion harmonics are reduced and the switching components of the inverter are under less stress. However, in comparison to traditional inverters, it does require a greater number of legs. Because the switches needed for the cascaded H-Bridge inverter are less expensive in five-phase systems, they are favoured over higher phase orders. Furthermore, the suggested inverter removes 5th order harmonics, something that is not possible with traditional inverters. A five-phase induction motor appropriate for variable speed driving applications is also suggested by this research. Lastly, utilizing pulse width modulation (PWM) converters and an FPGA controller, an experimental study is carried out to assess the dynamic performance of the suggested induction motor drive. Particular attention is paid to the In-Phase Opposition Disposition (IPD) PWM technique.

Improved DPWM modulation for reducing switching losses in cascaded H-bridge multilevel inverters

Improved DPWM modulation for reducing switching losses in cascaded H-bridge multilevel inverters

A Cascaded H-Bridge Multilevel Inverter with DC Cells Input Fault Tolerance Capability Based on PSC-PWM Control

Multilevel inverters have proven their efficiency in generating better AC voltage outputs. This functional quality is mainly due to the use of multi-source DC inputs. Despite the fact that this type of topology is generally reliable, switching faults caused by the complete loss of a switching component or DC input cell may still occur. Such incident may inflict heavy impacts to the conversion chain resulting in a permanent damage to the switching cells or the connected load. This article presents a dynamic switching control strategy capable of tolerating DC cells open-circuit input faults in basic symmetric Cascaded H-bridge multilevel inverter architectures. The proposed topology uses a control scheme to overcome the switching cells’ fault by adapting the configured level of conversion and bypassing the flawed unit with no additional switching components. Furthermore, the proposed control strategy is capable of reversing back the inverter configuration to its original functional state after the disappearance of the faut. This research article answers the need for a theorical study of a fault tolerant Cascaded H-Bridge multilevel inverter where the short circuit’s fault types are bypassed by Pulse width modulation alteration only.

A new method for selecting optimum levels in asymmetric Cascaded H‐Bridge‐Multilevel Inveter with variable DC sources

SummaryIn general, cascaded H‐bridge multilevel inverters (CHB‐MLI) are typically operated with either symmetrical or asymmetrical input DC sources, set at predefined specific ratios such as binary (1:2) or trinary (1:3) in the case of asymmetry, to achieve the desired output voltage waveform. However, if any DC source fails to provide the predefined voltage magnitude, or CHB‐MLIs with unspecified DC source ratios are utilized, the output voltage waveform may exhibit unequal magnitudes between consecutive levels, thereby causing a significant increase in total harmonic distortion (THD). Conventionally, to mitigate this effect, the corresponding H‐bridge is bypassed through zero voltage switching, which leads to an additional burden on the remaining H‐bridges to serve the same load. To reduce the burden on the remaining cells and improve the THD profile of the inverter, this article proposes a novel method for CHB‐MLI with varying DC magnitudes. It aims to enhance the quality of the output voltage waveform by strategically selecting optimum voltage levels rather than utilizing all available levels when CHB‐MLI has unspecified or variable DC sources. This approach can achieve a more balanced distribution of voltage magnitudes across successive levels by eliminating redundant states. Moreover, the proposed technique can reduce switch losses and enhance the converter's efficiency. The proposed method is validated through MATLAB/Simulink software simulations, followed by experimental verification.

Comparative Analysis of 5-Level and 7-Level Single-Phase Cascaded H-bridge Multilevel Inverters

The demand for high-performance, efficient, and reliable power electronic systems has been steadily increasing in various industrial applications, including renewable energy systems, electric vehicles, and smart grids. In response to this demand, the Cascaded H-Bridge Multi-level Inverter (CHB-MLI) has emerged as a promising solution, offering advantages such as improved voltage waveform quality, reduced harmonic distortion, and enhanced power handling capabilities. The CHB-MLI is characterized by its modular structure, comprising multiple H-bridge cells cascaded in series. Each H-bridge cell operates with a separate DC power source, enabling the generation of stepped voltage levels at the inverter output. By intelligently controlling the individual H-bridge cells, the CHB-MLI achieves the synthesis of a high-quality multilevel output voltage waveform. The different multi-level inverter topologies are Diode-Clamped MLI, Capacitor-Clamped MLI and Cascaded H-bridge MLI. This paper focused on key aspects like design, simulation, control strategies, performance evaluation, overall comparison and analysis of 5-level and 7-level CHB-MLIs. By addressing these aspects, this paper aimed to contribute to the advancement of power electronics technology and promote the adoption of the CHB-MLI in real-world applications, fostering energy efficiency and sustainability in power conversion systems. Index Terms: Inverter, Multi-level inverter, CHBMLI, switching, SPWM, MCSPWM, gate signal, waveform, harmonics, THD, MATLAB.

CHBMLI based DSTATCOM for power quality improvemt in a three-phase three-wire distribution system with PI controller

This paper presents a cascaded h-bridge (CHB) multilevel inverter (MLI) based MLI based distribution static synchronous compensator (DSTATCOM). The main objective of this paper is to reduce source current harmonics in the distribution system by using a cascade H-bridge multilevel inverter (CHBMLI) as DSTATCOM with a proportional-integral (PI) controller. The PI controller compensates reactive power, reduces source current harmonics, and maintains the unity power factor in the distribution system. The conventional two-level inverter-based DSTATCOM has many disadvantages such as high total harmonic distortion (THD), and high switching stress power semi-conductor devices, suitable for only low-power applications. This paper to overcome these drawbacks by using MLI-based DSTATCOM. The proposed system simulations are verified in MATLAB/Simulink software. The verified results are source current, load current, and compensating current.

Performance evaluation of novel 9-level RSMLI topology for grid-tied solar-PV system

The shortage of traditional fossil fuels like coal, petrol and natural-gas are increased day-by-day, fulfills the most of energy demand. Most of engineers are trying to maximize the energy demand by employing renewable energy with existing micro-grid system. Owing to merits, the solar-PV system plays a significant alternative among all other renewable energy sources due to abundant and virtuous nature. For grid-tied solar-PV system, the cascaded H-bridge multilevel inverter is the most significant over the classical 2-level inverter due to provision of isolated input DC sources. But the cascaded H-bridge topology is designed for limited voltage levels due to its larger number of switches for higher voltage levels, high cost, large-size, and more weight. To alleviate these demerits, a reduced-switch multilevel inverter has been generally preferable for higher voltage levels. In this work, a novel 9-level reduced-switch multilevel inverter (RSMLI) topology has been proposed by utilizing low number of switching devices. The performance of proposed novel 9-level RSMLI topology has been verified in grid-tied solar-PV system by using MATLAB/Simulink tool, simulation results are presented with attractive comparisons.

OSG-PLL-based method of a solar PV grid-interfaced transformer-less cascaded H-bridge multilevel inverter for power quality enhancement

OSG-PLL-based method of a solar PV grid-interfaced transformer-less cascaded H-bridge multilevel inverter for power quality enhancement

A Single-Phase Cascaded H-Bridge Multilevel Inverter With Voltage Boost Ability: Modulation and Analysis

A Single-Phase Cascaded H-Bridge Multilevel Inverter With Voltage Boost Ability: Modulation and Analysis

Review of Multilevel Level Inverter Using Different Topologies

This paper provides a concise overview of various multilevel inverter (mli) topologies. The conventional two-level voltage source inverter (vsi) necessitates a filter to generate sinusoidal output waveforms, which can be challenging at high frequencies due to switching losses. To address this issue, multilevel inverters offer lower switching frequencies and reduced total harmonic distortion (thd), eliminating the need for filters and large transformers. Moreover, a few advantages of mli inverters are reduced switching losses, better performance at high switching frequencies, and higher power quality (almost pure sinusoidal). Nevertheless, adding to the complexity of the system is the requirement for each switch to have its own gate driver in order to perform mli. Thus, it's imperative to decrease the mli's number of switches. In order to reduce the number of switches needed, this paper reviews some of the various current topologies. Applications such as voltage regulation, var compensation, harmonic filtering in power systems, and user interface for renewable energy have led to the development of cascaded h-bridge multilevel inverters. For solar applications, a modified cascaded h-bridge multilevel inverter (mli) is used. Cascaded h-bridge topology multilevel inverter will aid in reducing the number of switches. Comparing this concept to other multilevel inverters, the switching complexity is reduced.

Comparing performance and complexity of TCHB and CHB multilevel inverters using NLC technique

This paper presents a modulation strategy applied to a 13-level three-phase transistor clamped H-bridge (TCHB) inverter, aimed at a renewable and electric vehicle drives application. A comparison is performed between the TCHB inverter and a traditional cascaded H-bridge (CHB) inverter, considering circuit complexity, switching losses, and total harmonic distortion (THD) attained from each multilevel inverter topologies. The TCHB inverter achieves a 13-level output with only 15 switches, whereas the conventional CHB inverter requires 24 switches. The modulation technique, employing a nearest level control, yields improved output quality for both the TCHB and CHB multilevel inverters. The results demonstrate that this strategy effectively minimizes the overall THD. Notably, previous modulation techniques mainly focused on carrier-based PWM or SVPWM, making this approach distinctive. The FFT analysis reveals a voltage THD of 5.49% for TCHB and 5.15% for CHB, indicating a marginal difference in THD content for each multilevel inverter. Despite the CHB inverter experiencing double the switching stress compared to TCHB, since less switches are required in the TCHB inverter, consequently, the system's total cost and complexity are reduced. The achieved results are verified through the use of simulations carried out in the MATLAB Simulink.

Cascaded H–Bridge Multilevel Inverter: Review of Topologies and Pulse Width Modulation

Multilevel inverters (MLIs) have become more popular for medium-voltage and high-power applications. The cascaded H-bridge multilevel inverter (CHBMLI) is one of the three most popular topologies of MLIs. It was more reliable due to its fewer components per level. The number of possible output voltage levels is more than twice the number of DC sources, the most suitable topology for integration with renewable energy sources, easy to design, and has good performance with modularity. The main disadvantage of CHBMLI is the need for separate DC sources for each H-bridge. However, this can be considered as an advantage to be employed in renewable energy applications. This paper provides a review of CHBMLI topologies and pulse width modulation (PWM) techniques, including fundamental and high switching frequency techniques, such as selective harmonic elimination (SHE), space vector modulation (SVM), nearest level modulation (NLM), and Carrier-Based PWM.

2DOF‐FOPID‐IF control with improved sparrow modulation for cascaded H‐bridge multilevel inverter in PV applications

SummaryPhotovoltaic (PV) systems benefit from the cascaded H‐bridge multilevel inverter (CHMLI) topology due to its high flexibility and efficiency. However, PV mismatches in three‐phase grid‐connected systems result in an unbalanced power supply, which leads to an unbalanced grid current. Proportional integral derivative (PID) controllers can be used to control H‐bridge inverters because of their simplicity of tuning as well as their basic structure. However, due to the nonlinearity and high sensitivity of the PID controller, its performance declines as a result of high overshoot, high settling time, and high rise time during significant external disturbances. Moreover, the switching angle of the inverter must be adjusted to provide the required fundamental voltage while reducing harmonic content. In order to address this problem, a control technique with modulation compensation is proposed. The present work offers a two‐degree‐of‐freedom fractional‐order PID controller with an integrated filter (2DOF–FOPID–IF). Moreover, the optimum switching angles are determined for the CHMLI by employing an improved sparrow optimization (ISO) algorithm. To prove the practicality of the suggested technique, simulation, and experimental data are compared with the existing techniques. The proposed technique shows better performance in terms of settling time, overshoot, rise time, and low harmonics.

Power Quality Assessment and Enhancement using FLC based SPV Supported Cascaded H-Bridge Multilevel Inverter

Solar photovoltaic (SPV) is one of the most common renewable energy sources used at present. The major issue with renewable energy resources is power quality to meet the growing energy demand. In recent times reliability and flexibility of energy supply are also associated with the quality of power. The issues attached with line faults, voltage sag/swell, harmonics in supply and flicker are the key concerns for poor power quality. The new scenario is designed to challenge electrical resources like generation, transmission and distribution. Considering renewable energy in the existing power system requires additional research and analysis to synchronize new components. From this point of view, many power electronics converters and switching devices are designed to increase the reliability and efficiency of the system. Similarly, solar PV system requires a maximum power point tracker to extract the power upto the maximum extent. It consists of two stages: DC to DC converter and Pulse Width Modulation controlling phase. A multi-level inverter (MLI) is used to enhance the power quality of the overall system. It reduces the harmonics distortion and stabilizes the system near the unity power factor. This paper comprehensively analyses the cascaded H-bridge Multilevel Inverter associated with the fuzzy logic controller (FLC) and SPV system. The simulation results are compared with the 3-level and five levels Multilevel Inverter.

Development of Sliding Mode Control-Adaptive Neuro-Fuzzy Inference Strategy Algorithm for Three-Phase 15-Level MLI

A comparative analysis was conducted in current research on the control strategies utilized in three-phase 15-level Cascaded H-Bridge Multilevel inverter (CHBMLI)-fed different RL loads with a three-phase induction motor, generally applied in industries. The analysis of 15-level CHBMLI, with Sliding Mode Control (SMC), the sliding mode control with an artificial neural network (SMC-ANN), and sliding mode control with an Adaptive Neuro-Fuzzy Inference Strategy (SMC-ANFIS) controller are explained. The study compared the performance achieved by controllers at four different speeds of a 3ϕ inductor motor and parallel-connected RL load dynamic change under closed-loop operations. The comparative study results demonstrate that there should be a reduction in the methodology suggested in terms of both the quantity of power devices and Total Harmonic Distortion (THD). The researcher conducted the experimentation procedures to authenticate the proposed 15-level MLI topology's performance. The SMC-ANFIS control technique produces less voltage and lower current total harmonic distortion of 5.53% and 2.74% compared to the SMC-ANN control technique in both simulation and real-time implementations.

A hybrid search space reduction algorithm and Newton–Raphson based selective harmonic elimination for an asymmetric cascade H-bridge multi-level inverter

Abstract In this paper, a selective harmonic elimination (SHE) method for an asymmetric cascade H-bridge multi-level inverter (ACHB-MLI) has been performed by using hybrid search space reduction and Newton–Raphson (SSR-NR) algorithm. Three H-bridges are cascaded in a single phase configuration, while each of the bridge is fed with V dc , 3V dc and 6V dc respectively. This particular asymmetric combination of dc sources will produce 10 possible switching combinations and 21-levels in the output voltage ranging from −10V dc to +10V dc . Hence, there will be 10 SHE equations corresponding to fundamental and harmonics, and the solution will be the 10 switching angles which satisfy those SHE equations. While traditional gradient-based techniques like the Newton–Raphson method can yield the global optimal solution for the SHE equations, they necessitate an initial guess. Conversely, meta-heuristic methods often face challenges related to sub-optimal convergence. To address these issues, a novel the hybrid SSR-NR algorithm has been introduced in this paper. This method combines stochastic and deterministic elements, offering a promising solution for solving the SHE equations. In the first step, the evolutionary SSR algorithm will be used and the output of the SSR algorithm is given to the NR method as an initial guess to converge to the final solution, this way the proposed hybrid SSR-NR algorithm is able to address the drawbacks of both the algorithms such as initial guess requirement for NR method and sub-optimal convergence characteristics of evolutionary algorithms. The simulations were carried out in Matlab/simulink environment for a 21-level ACHB-MLI. The results obtained showcase the efficacy of the proposed SSR-NR algorithm in solving the SHE equations. For demonstrating the effectiveness of SSR algorithm the results were also compared with other algorithms such as particle swarm optimization and grey wolf optimizer as well. Further, the experimental results on a laboratory prototype using dSPACE DS1104 R&D controller board were also presented in the paper, to validate the proposed methodology.

Application of cascaded H-bridge multilevel inverter in the speed regulation of medium- and high-voltage asynchronous motor

Application of cascaded H-bridge multilevel inverter in the speed regulation of medium- and high-voltage asynchronous motor