Inverter Topology Research Articles

Novel multilevel inverter topology with low switch count

Abstract This paper aims to introduce a new multilevel inverter topology less number of switches and gate drivers with a hybrid control method. In the proposed topology three kinds of voltage sources are utilized in the topology. A combination of these voltage sources, switches, and two H-bridges derived a new topology. Moreover, combining the nearest level and pulse width modulation created an efficient way to control the proposed topology which is described in this paper. Equations to determine the number of components and total standing voltage of the proposed multilevel is presented. A comprehensive comparison between the proposed topology and other best topologies is made. Additionally, the simulation results which are obtained by PSCAD/EMTDC and experimental results are in accordance with the theory. The proposed multilevel inverter with a hybrid control method has less number of switches, gate drivers, and low THD.

A New Integrated Multilevel Inverter Topology for Renewable Energy Transformation

This paper presents a new three-phase integrated module multilevel inverter (IMMLI) with reduced component count which is suitable for low, medium and high voltage renewable energy systems. The proposed inverter is a resultant structure of a number of integrated module and each module is configured with a number of series connected basic blocks. Each block consists of a dc voltage source, a blocking diode and a semiconductor switch. A computational combination and summation among the dc sources from different blocks results in a high number of levels within the output voltage. This task is performed by controlling the switches equipping appropriate switching algorithm. Thus, a high level of output is obtained employing reduced number of components. Since the topology owns two degree of modularity, the total stress voltage (TSV) of the system is low and distributed among the switches. Hence, the proposed topology allows to be implemented in high power systems with reduced amount of costs. The inverter also offers enhanced efficiency, as the number of simultaneously conducting switch is low. Additionally, in order to operate the presented inverter with optimum ac power quality, a multi-carrier based level shifted PWM scheme is addressed in this paper. This paper also shows how to prepare balanced dc sources that are required to implement the inverter using high-frequency magnetic-link. The operating principle of the IMMLI is explained with the help of a fifteen level (15-L) single phase unit and its performance is evaluated in MATLAB/Simulink considering different conditions. Experimental validation is also presented to support the simulation results and to evaluate its superiority over the existing.

Neutral Point Clamped Non-Isolated Three Phase Grid-Integrated PV Inverter Topologies for Leakage Current Reduction

Neutral Point Clamped Non-Isolated Three Phase Grid-Integrated PV Inverter Topologies for Leakage Current Reduction

Runge–Kutta optimization‐based selective harmonic elimination in an H‐bridge multilevel inverter

AbstractThe application of iterative techniques for solving the Selective Harmonic Elimination Pulse Width Modulation (SHE‐PWM) problem, such as the Newton–Raphson (NR) method, can tend to get stuck at local optima in the solution space. Additionally, these methods may be sensitive to the initial value estimation of the solution. In contrast, metaheuristic approaches demonstrate resilience in seeking out the optimal solution. As such, this study utilizes the Runge–Kutta (RUN) metaheuristic optimization algorithm to demonstrate the SHE‐PWM technique in multilevel inverters (MLIs), including 5‐ and 7‐level modified H‐bridge (MHB) topology and a 9‐level asymmetric cascaded H‐bridge (CHB) inverter topology. The switching angles are obtained by varying the modulation index from 0.01 to 1.0 in steps of 0.01 for 5‐, 7‐, and 9‐level MLIs. The performance of the RUN algorithm in minimizing the total harmonic distortion (THD) value is verified through simulations in MATLAB/Simulink software. The superiority of RUN is established by comparing the results with state‐of‐the‐art metaheuristic algorithms, such as the Differential Evolution (DE), Genetic Algorithm (GA), and Grey Wolf Optimizer (GWO). Additionally, the switching angles obtained through RUN are validated by hardware experiments. According to the simulation and experimental results, the proposed RUN method exhibits better performance in terms of objective function values, algorithm robustness, fundamental harmonic magnitude, and THD values. The findings confirm the elimination of fifth harmonic, fifth, and seventh harmonics, and fifth, seventh, and ninth harmonics in 5‐, 7‐, and 9‐level MLIs, respectively.

Grid-Tied Single-Phase Integrated Zeta Inverter for Photovoltaic Applications

Recently, the development of integrated inverters for photovoltaic systems has been widely performed to reduce overall system size, costs, and losses. Thus, integrated inverters have emerged as a prominent solution for replacing two-stage power conversion composed of a step-up converter and a voltage source inverter. Thereby, this paper proposes an integrated inverter topology for single-phase grid-tied photovoltaic systems. The proposed power converter, called a Single-Phase Integrated Zeta Inverter (SP-IZI), can boost the input voltage and inject a sinusoidal and regulated current into the mains with low harmonic distortion. The SP-IZI is based on integrating modified DC-DC Zeta converters, designed and controlled to operate in a discontinuous conduction mode, and presents similarities with the Modified Zeta Inverter (MZI). In this way, this paper compares the main parameters of both topologies and provides a complete study of the SP-IZI, involving both quantitative and qualitative studies as well as a small signals analysis. The feasibility and functionality of the proposed SP-IZI inverter are presented and evaluated through experimental results, which demonstrate that the SP-IZI presents the following advantages compared to the MZI: (i) the voltage in coupling capacitors is 13% lower; (ii) voltage stresses in switches and diodes are 40% lower; and (iii) static gain is similar to the traditional Zeta converter.

Comparison between a Cascaded H-Bridge and a Conventional H-Bridge for a 5-kW Grid-Tied Solar Inverter

This paper compares the cost and efficiency of two inverter topologies for a 5-kW grid-connected solar inverter application: the Conventional H-Bridge Inverter (CHB) and the Cascaded H-Bridge Multilevel Inverter (CHBMLI). Emphasis is put on power switches and passive elements with a detailed study of the losses. Both designs respect the same constraints (cost, efficiency, and junction temperature of the transistors) to ensure a fair comparison between both topologies. The work highlights the important parameters when choosing the components (MOSFETs, capacitors, and magnetic cores for the inductors). The DC-link voltage ripple and the output AC current ripple are the key parameters for the design of the passive elements (capacitors and inductors). On top of that, the transistors MOSFETs are chosen, in both topologies, to limit the conduction losses (by selecting the Rdson) and the switching losses (by selecting the Qrr and dv/dt). Real components are picked in order to make the comparison as complete as possible. Numerical simulations are performed using the MATLAB platform. All equations and parameters are provided. A CHBMLI prototype was built with eight independent H-Bridges to validate the proposed design with thermal and efficiency measurements.

A Triple Boost Seven-Level Common Ground Transformerless Inverter Topology for Grid-Connected Photovoltaic Applications

This article proposes a single-stage, seven-level (7L), switched-capacitor-based grid-connected inverter architecture with a common ground feature. This topology has the ability to boost the output voltage up to three times the input voltage. The proposed topology can diminish the leakage current in grid-connected photovoltaic (GC-PV) applications, and its capacitor voltages are self-balanced without any additional control strategies. The different operating modes are described in detail with their related mathematical expressions. The design of passive components and a detailed power loss analysis are presented. The merits of the proposed structure are demonstrated using a detailed comparative assessment. The grid-connected operation of the proposed inverter structure is simulated in the MATLAB/Simulink environment, and the results are presented. The laboratory prototype of 935 W is built and analyzed to validate the performance of the proposed structure.

Grid Interconnection Modeling of Inverter Based Resources (IBR) Plant for Transient Analysis

The increase in penetration levels of inverter-based resources (IBRs) is changing the dynamic performance of power grids of different parts of the world. IBRs are now being more and more integrated into the grid at a single connection point as an IBR plant. Due to the complex nature and dynamicity of each inverter model, it is not realistic to build and analyze full complex models of each inverter in the IBR plant. Moreover, simulating a large plant including detailed models of all the IBRs would require high computing resources as well as a long simulation time. This has been the main issue addressed in the new IEEE Std 2800-2022. This paper proposes a novel approach to model an IBR plant, which can capture the transient nature at the plant level, detailed IBR control at the inverter level, interactions of multiple IBR groups in a plant structure, and a collector system connecting the IBRs to the grid. The IBRs in the plant use a voltage source inverter topology combined with a grid-connected filter. The control structure of the IBR includes a cascaded loop control where an inner current control and outer power control are designed in the dq-reference frame, and a closed-loop phase-locked loop is used for the grid synchronization. The mathematical study is conducted first to develop aggregated plant models considering different operating scenarios of active IBRs in an IBR plant. Then, an electromagnetic transient simulation (EMT) model of the plant is developed to investigate the plant’s dynamic performance under different operating scenarios. The performance of the aggregated plant model is compared with that of a detailed plant model to prove the effectiveness of the proposed strategy. The results show that the aggregated EMT simulation model provides almost the same result as the detailed model from the plant perspective while the running time/computation burden is much lower.

Single-phase transformerless inverter topologies at different levels for a photovoltaic system, with proportional resonant controller

<span lang="EN-US">In this paper, we have studied the topologies of single-phase transformerless inverters with different levels using a <a name="_Hlk115945664"></a>proportional-integral-resonant (PIR) AC controller, and the multi-level cascade inverter topology with sinusoidal pulse with modulation (SPWM) control in an open and closed loop. To ensure that these photovoltaic inverters can inject a defined amount of reactive power into the grid according to international regulations. Therefore, precise monitoring of the mains voltage vector by a phase-locked loop (PLL) system is applied to ensure the proper functioning of this system. For inverter topologies with less than three levels, the simulation results show that the highly efficient and reliable inverter concept (HERIC) topology performance is better than that of H5 and H6. On the other hand, the performance of the topology H6 ameliorate is superior to those of H4, H5, and HERIC in currents of leakage. On the other hand, for the control of cascaded multi-level closed-loop inverters, we notice that there is an improvement in the spectra and the elimination of all frequency harmonics, close to that of the fundamental, and a reduction in the rate of harmonic current distortion.</span>

Integrated Control Strategy for Distortion Current Elimination of Fault-Tolerant Open-End Winding Permanent Magnet Synchronous Machine With Topology Reconfiguration

This article proposes a reconfigured topology of a five-leg inverter for the open-end winding permanent magnet synchronous machine (OW-PMSM) driving system after the device fault condition. Due to the asymmetric structure and common dc bus of the reconfigured fault-tolerant five-leg inverter, the zero-sequence current generated by the dead-time effect and inherent third harmonic voltage of the open-end winding will deteriorate the output torque and the efficiency of the driving system. Thus, the asymmetric property and dead-time effect of the five-leg inverter on the distortion currents of OW-PMSM are analyzed, and an integrated control method with the closed-loop of zero-sequence current and the compensation of dead-time effect and third harmonic voltage are employed to suppress the distortion current for the low-current total harmonic distortion (THD) of the OW-PMSM. The effectiveness and validity of the high-performance OW-PMSM driving system based on the five-leg inverter were verified by the simulation and experimental results.

A cascade multi-level inverter topology with reduced switches and higher efficiency

The use of multi-level inverter (MLI) technologies in high-power, medium-voltage energy regulation has been more popular in recent years. Despite the fact that the multilayer inverter has a lot of benefits, it has certain disadvantages in the layer of higher levels due to the enormous number of semiconductor switches that it employs in its construction. This may result in the inverter being of a huge size and costing a lot of money, as well as a significant rise in losses. As a result, the new MLI is suggested to minimize the number of switches in order to alleviate these challenges. This article describes a cascaded multilevel inverter with lower devices. The suggested cascaded multilevel inverter is intended for use in minimizing total harmonic distortion (THD), as shown in MATLAB/Simulink by the graph. Multilevel inverters benefit from the switching pattern of semiconductor switches, which may be used to improve their overall performance. This approach lowers the switching loss while simultaneously increasing the efficiency. In order to validate the suggested approach, simulations are carried out using the MATLAB/Simulink programming environment.

Research on Inverter Side Control of Power Grid Simulator Based on Active Disturbance Rejection and Repetitive Control

To track the input voltage waveform quickly and accurately, and sort out waveforms on the power grid simulator, a control strategy is proposed. The first loop use repeated control (RC) and PI Control composite control, and the voltage inner loop is controlled by a first-order linear self-disturbance rejection controller (ADRC). A suitable inverter topology is also designed. To improve the performance of the proposed controller, the bandwidth method is selected to adjust the observer bandwidth. In view of the frequency adaptability of inverters on the inverter side, the output voltage imbalance is suppressed by improving the repetitive control and the tracking accuracy is improved. The simulation results indicate the controller has the ability to track the waveform quickly and accurately. In addition, the waveform jitter is effectively suppressed.

Review and comparison of methods for limiting leakage currents in single-phase transformerless PV inverter topologies

Transformerless inverters are widely used in different photovoltaic nonisolated ac module applications, mainly in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency over a wide load range, and low cost. Various transformerless inverter topologies have been proposed to meet the safety requirement of low ground leakage currents, such as specified in the VDE-4105 standard and low-output ac-current distortion. Topology modifications of transformerless full bridge inverters are designed to balance and maintain a constant common mode output voltage, thereby eliminating or reducing leakage currents. This article reviews and compares the different methods for limiting leakage currents in known topologies of the full-bridge transformerless inverters, such as: H4, H5, H6, HERIC, and their improvements. The main topologies and strategies used to reduce the leakage current in transformerless schemes are summarized, highlighting advantages and disadvantages and establishing points of comparison with similar topologies. To compare the properties of different medium to high power inverters, PV inverter topologies were implemented using IGBTs and tested with the same components, same simulation parameters in PSPICE to evaluate their performance in terms of energy efficiency and leakage current characteristics. The detailed power stage operating principles, extended PWM modulator, and integrated universal gate driver with galvanic isolation in the transmission path of control signal for all IGBTs of the inverter, as well isolated and floating bias power supply for gate drivers are described.

Model-Free Predictive Current Control of a 3-φ Grid-Connected Neutral-Point-Clamped Transformerless Inverter

Utility grid-tied photovoltaic (PV) installations are becoming a typical component of the current electrical energy grid. The adoption of transformerless inverters has recently changed the topology of these systems. Despite being small, inexpensive, and effective, transformerless inverters have a recurring leakage current issue. Numerous studies are being conducted to improve its performance and bring the leakage current down to acceptable levels. The studies propose three tracks for addressing the leakage current problem of transformerless PV systems: the control technique, the inverter modulation, and the inverter topology. This study applies the model-free predictive control (MFPC) technique to a grid-connected NPC 3-φ transformerless converter powered by a PV panel. An LCL filter connects the transformerless inverter to the grid. The system model considers the grid filter components and the internal impedance of the utility grid. The proposed system’s discrete model is established before describing the MFPC controller’s algorithm. The suggested system is simulated in MATLAB using the MFPC and a standard PI current controller with SVPWM modulation. According to the simulation’s findings, the MFPC controller performs best regarding current spectrum, THD, and earth leakage current. Additionally, MFPC-based systems are more efficient than those that use PI controllers.

Control Parameter Analysis for an SRM Inverter for Range Extender Units with Integrated DC–DC Converter

In modern electrical traction drives, a variable dc-link voltage can be applied to increase efficiency in partial load. A dc-dc converter can supply a variable dc-link voltage and transfer energy between the battery and the dc-link. Hybrid cars combine the advantages of long driving ranges with the partial zero-emission operation. In series-hybrid drive trains, a switched reluctance machine can be used as a generator for the range extender unit. This paper presents at first the mechanism of energy transfer between the battery and the dc-link. Further, a control parameter analysis of an inverter topology for a switched reluctance machine, which combines the dc-dc converter for the power transfer between the battery and the dc-link with the inverter for the generator, is investigated. For this analysis, the control parameters turn-on, freewheeling and turn-off angle are varied to test the controllability of the energy transfer between these two components. The simulation results of the presented analysis are finally validated with measurements on the test bench.

DTC Based on Five-level SVM with Balancing Strategy of Sensorless DSSM

This paper presents a direct torque control based on multilevel space vector modulation of a double star synchronous machine operating without speed sensor. Each star of the machine is supplied by a five-level diodeclamped inverter. This topology of multilevel inverters represents one of the most interesting solutions to increase voltage and power levels and to achieve high quality voltage waveforms. However, a very important issue in using diode-clamped inverters is the ability to guarantee the stability of the DC-link capacitor voltages. To overcome this problem the multilevel space vector modulation equipped by a balancing strategy is proposed to suppress the unbalance of DC-link capacitor voltages. For achieving high performances control of the multiphase drive, the proposed control method needs accurate information about rotor position and rotor speed. To this end, they are estimated by using Luenberger observer.

A novel bidirectional modular multilevel inverter utilizing diode‐based bidirectional unit

SummaryMultilevel inverters have many applications, such as the grid integration of photovoltaic cells, FACTSs devices, electric vehicles, variable speed drives, and smart grids. In this paper, a new bidirectional diode‐based unit is proposed for a symmetric single‐phase modular inverter topology that can achieve high output levels by using a small number of switching and circuit devices. The basic structure can generate nine‐level voltage with only nine IGBTs and two diodes. Another advantage of the proposed topology is the utilization of a half‐bridge module to change the voltage polarity and the low number of its voltage sources. Additionally, the proposed topology can be used as the cascaded structure with different approaches to select the value of voltage sources. The power losses are discussed for the proposed basic module. A comparison has been made with some recently presented topologies to compare the proposed multilevel inverter and demonstrate its superiority. The comparison is performed for the basic module and its generalized structure. In this paper, the pulse width modulation technique is utilized to achieve a voltage waveform with low harmonic content. The proposed basic structure has an efficiency of 58.98% in 5KW power. Finally, the operation of the proposed basic module is simulated, and the laboratory prototype results confirm the accuracy of the simulation results.

High Step-Up Thirteen Level Switched-Capacitor Inverter Topology for HFAC Power System

This article proposes two new high-frequency, thirteen-level switched capacitor inverter topologies. Compared with the counterpart existing topologies, which were recently published, the switch count, capacitor voltage, and voltage stress on the switch are reduced. In addition, the proposed topologies have inherited merits such as six-time voltage boosting levels and self-balanced capacitor voltages as well. The capacitor ripple voltages and the proposed topology performance are analyzed. The prototype setup is developed for 500W, and the results are verified. The maximum efficiency is approximately equal to 97.5% for simulation. Furthermore, it is approximately equal to 96.1% for experimental, and both are measured at an output power of 500 W. Finally, the characteristics of the proposed topologies are tested under several scenarios, such as modulation index variations and load changes, and the findings are reported.

Research on life prediction control of MMC submodule based on fiber sensing

With the rapid development of energy, power electronic equipment plays a crucial role in renewable energy. Modular multilevel converter (MMC) has turned into cutting-edge inverter topology in flexible HVDC and offshore wind power situations. However, under the conditions of high humidity and high voltage, the internal submodules lifetime of MMC might be affected. The system reliability mainly depends on good running of the submodules, so stable performance of the submodules serious threat to the normal operation of the inverter. Therefore, this paper proposes a model based on Peck accelerated life predictable model, and model predictive control (MPC) strategy is improved, at the same time without affecting the external characteristics can better control the submodule voltage fluctuations. What is more, real time monitoring of the working environment of the converter through the optical fiber sensing module. Finally, the experimental and simulative outcomes show that the proposed control strategy can effectively reduce the voltage fluctuations in the small module, and the life parameters of the submodules can be obtained in real time by bringing the results into the proposed life prediction model. By comparing the results, the results can be obtained the proposed control strategy can effectively increase the reliability of the submodule.

H9 and H10 Transformer-Less Solar Photovoltaic Inverters for Leakage Current Suppression and Harmonic Current Reduction

Now-a-days, transformer-less inverters integrating renewable energy resources as solar photovoltaic systems are commonly employed in many grid-connected distributed energy systems in both industrial and residential settings. Transformer-less photovoltaic (TLPV) inverters have attracted increased attention due to their unique advantages, such as increased efficiency, low cost, and ease of installation. Converting fluctuating solar dc power to consistent ac power has been a difficulty in the recent decade to avoid security risks like ground fault currents and leakage currents. Leakage current minimization is one of the most crucial factors in the TLPV inverters. Different TLPV inverter topologies have been presented in the past, with leakage current being reduced by galvanic isolation on the dc or ac side of the inverter, common mode voltage (CMV) clamping, and modulation techniques. This paper proposed two novel single-phase grid-tied TLPV inverter topologies with control blocks, which can handle a wide variety of grid voltages. The proposed TLPV inverters offer very small leakage current, reduced total harmonic distortion (THD), and improved power quality. Based on the number of semiconductor devices, the proposed inverters are termed as H9 and H10 inverters. The switches are controlled using the unipolar sinusoidal pulse width modulation, which results in constant common mode voltage and reduction in leakage currents to 11.09 and 11.73 mA for the proposed H9 and H10 inverters, respectively. The proposed H9 and H10 inverters minimize the THDs to 1.62 and 2.09%, respectively. Besides, the proposed H9 and H10 inverters exhibit 98.19 and 98.12% European efficiency. The simulations are carried out on MATLAB/Simulink and the results are experimentally validated using downscale laboratory test platforms