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The purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output voltage THD.

In cascaded multi‐level inverters, it is usually assumed that the DC sources have the same constant voltage and output harmonics minimization is accomplished by applying proper switching angles. Employing different DC voltages with proper ratios can result in further reduction of the harmonics. After formulation of the system, i.e. describing the inverter's output voltage components in terms of the switching angles and unequal DC source voltages, a rule is applied to obtain the step heights of the staircase output waveform (DC source voltages), so that the output waveform becomes as close to the required fundamental sine wave as possible. Substituting the obtained DC source voltages into the harmonics elimination equations results in a set of equations, which are functions of switching angles only. Solving these equations leads to proper switching angles, which, regardless of the fundamental component's value, provide the specified harmonic conditions. The output voltage is then controlled by DC sources voltage regulation.

Computer simulations show that employing the proposed concept results in substantial improvement in the harmonic minimization, as well as, extending the operating range of the inverter, compared to the conventional methods with equal DC source voltage multi‐level inverters.

The proposed concept according to which the ratio of the DC source voltages are determined, is original.

Multi‐level diode‐clamped inverters have the challenge of capacitor voltage balancing when the number of DC‐link capacitors is three or more. On the other hand, asymmetrical DC‐link voltage sources have been applied to increase the number of voltage levels without increasing the number of switches. The purpose of this paper is to show that an appropriate multi‐output DC‐DC converter can resolve the problem of capacitor voltage balancing and utilize the asymmetrical DC‐link voltages advantages.

A family of multi‐output DC‐DC converters is presented in this paper. The application of these converters is to convert the output voltage of a photovoltaic (PV) panel to regulate DC‐link voltages of an asymmetrical four‐level diode‐clamped inverter utilized for domestic applications. To verify the versatility of the presented topology, simulations have been directed for different situations and results are presented. Some related experiments have been developed to examine the capabilities of the proposed converters.

The three‐output voltage‐sharing converters presented in this paper have been mathematically analysed and proven to be appropriate to improve the quality of the residential application of PV by means of four‐level asymmetrical diode‐clamped inverter supplying highly resistive loads.

This paper shows that an appropriate multi‐output DC‐DC converter can resolve the problem of capacitor voltage balancing and utilize the asymmetrical DC‐link voltages advantages and that there is a possibility of operation at high‐modulation index despite reference voltage magnitude and power factor variations.

The main purpose of this paper is to select appropriate voltage vectors in the switching techniques and, by selecting the proper voltage vectors, be able to achieve a DC link with the same outputs and a symmetric multi-level inverter.

The proposed structure, a two-stage DC–AC symmetric multi-level inverter with modified Model Predictive Control (MMPC) method, is presented for Photovoltaic (PV) applications. The voltage of DC-link capacitors of the boost converter is controlled by MMPC control method to select appropriate switching vectors for the multi-level inverter. The proposed structure is provided for single-phase power system, which increases 65 V input voltage to 220 V/50 Hz output voltage, with 400 V DC link. Simulation results of proposed structure with MMPC method are carried out by PSCAD/EMTDC software.

Based on the proposed structure and control method, total harmonic distortion (THD) reduces, which leads to lower power losses and higher circuit reliability. In addition, reducing the number of active switches in current path causes to lower voltage stress on the switches, lower PV leakage current and higher overall efficiency.

In the proposed structure, a new control method is presented that can make a symmetric five-level voltage with lower THD by selecting proper switching for PV applications.

The purpose of this paper is to check the Solar Photovoltaic (PV) inverter working condition with modified unipolar switching pulse. The gate pulse for the inverter switches is generated in MATLAB simulation and interfaced with hardware protype. Simulation results can be compared with hardware results.

A considerable amount of research has been done on different Pulse Width Modulation (PWM) techniques. Based on the findings, a modified Unipolar Sinusoidal PWM technique was created with one reference signal and two carrier signals+ (one for the positive half cycle and the other for the negative half cycle) and simulated in the MATLAB/Simulink platform. The prototype inverter module receives the simulated switching pulses via dSPACE DS1104 hardware software interfacing board. The hardware implementation has been done, and the hardware results compared with simulation results for various input voltage levels using resistive load.

This modified switching pulse has dead band and additional hardware setup is not required. 3-phase multi-level inverter output waveform has been achieved with six switches in this method and with low filter values, pure sine wave output can be obtained in simulation. By this method of switching pulse generation and testing, for every modification in switching pulse hardware gate driver is not required. Resulting time consumption and money investment are lower.

Modified Unipolar SPWM pulse generation technique is novel method for solar PV inverter. The switching pulse has been designed and tested in both MATLAB/Simulation and hardware prototype inverter. Hardware and software results are identical. This method of pulse generation and hardware implementation has not been done anywhere before.

Industrial drives require appropriate control systems for reliable and efficient performance. With synchronous reluctance machines (SynRMs) slowly replacing the most commonly used induction, switched reluctance and permanent magnet machines, it is essential that the drive and its control be properly selected for enhanced performance. But the major drawback of synchronous reluctance motor is the presence of high torque ripple as its design is characterized by large number of variables. The solutions to reduce torque ripple include design modifications, choice of proper power electronic inverter and PWM strategy. But little has been explored about the power electronic inverters suited for synchronous reluctance motor drive to minimize torque ripple inherently by obtaining a more sinusoidal voltage. The purpose of this paper is to elaborate on the potential multilevel inverter topologies applicable to SynRM drives used in solar pumping applications.

The most significant field-oriented control using maximum torque per ampere algorithm for maximizing the torque production is used for the control of SynRM. Simulation results carried out using Matlab/Simulink are presented to justify the choice of inverter and its control technique for SynRM.

The five-level inverter drive gives lesser core or iron losses in the SynRMin comparison to the three- and two-level inverters due to lower Id current ripple. The five-level inverter reduces the torque ripple of the SynRM significantly in comparison to the three- and two-level inverter fed SynRM drives. The phase disposition-PWM control method used for the inverter shows the least total harmonic distortion (THD) levels in output voltage compared with the other level shifted PWM techniques.

Among the available topologies, a fitting topology is proposed for use for the SynRM drive to have minimal THD, minimal current and torque ripple. Additionally, this paper presents various modulation techniques available for the selected drive system and reports on a suitable technique based on minimal THD of output voltage and hence minimal torque ripple.

Power‐electronic systems have been playing a significant role in the integration of large‐scale wind turbines into power systems due to the fact that during the past three decades power‐electronic technology has experienced a dramatic evolution. This second part of the paper aims to focus on a comprehensive survey of power converters and their associated control systems for high‐power wind energy generation applications.

Advanced control strategies, i.e. field‐oriented vector control and direct power control, are initially reviewed for wind‐turbine driven doubly fed induction generator (DFIG) systems. Various topologies of power converters, comprising back‐to‐back (BTB) connected two‐ and multi‐level voltage source converters (VSCs), BTB current source converters (CSCs) and matrix converters, are identified for high‐power wind‐turbine driven PMSG systems, with their respective features and challenges outlined. Finally, several control issues, viz., basic control targets, active damping control and sensorless control schemes, are elaborated for the machine‐ and grid‐side converters of PMSG wind generation systems.

For high‐power PMSG‐based wind turbines ranging from 3 MW to 5 MW, parallel‐connected 2‐level LV BTB VSCs are the most cost‐effective converter topology with mature commercial products, particularly for dual 3‐phase stator‐winding PMSG generation systems. For higher‐capacity wind‐turbine driven PMSGs rated from 5 MW to 10 MW, medium voltage multi‐level converters, such as 5‐level regenerative CHB, 3‐ and 4‐level FC BTB VSC, and 3‐level BTB VSC, are preferred. Among them, 3‐level BTB NPC topology is the favorite with well‐proven technology and industrial applications, which can also be extensively applicable with open‐end winding and dual stator‐winding PMSGs so as to create even higher voltage/power wind generation systems. Sensorless control algorithms based on fundamental voltages/currents are suggested to be employed in the basic VC/DPC schemes for enhancing the robustness in the entire PMSG‐based wind power generation system, due to that the problems related with electromagnetic interferences in the position signals and the failures in the mechanical encoders can be avoided.

This second part of the paper for the first time systematically reviews the latest state of arts with regard to power converters and their associated advanced control strategies for high‐power wind energy generation applications. It summarizes a variety of converter topologies with pros and cons highlighted for different power ratings of wind turbines.

The purpose of this paper is to analyze the redistribution of dopant and radiation defects to determine conditions which correspond to decreasing of elements in the considered inverter and at the same time to increase their density.

In this paper, the authors introduce an approach to increase integration rate of elements in a three-level inverter. The approach is based on decrease in the dimension of elements of the inverter (diodes and bipolar transistors) due to manufacturing of these elements by diffusion or ion implantation in a heterostructure with specific configuration and optimization of annealing of dopant and radiation defects.

The authors formulate recommendations to increase density of elements of the inverter with a decrease in their dimensions.

Optimization of manufacturing of integrated circuits and their elements.

The results of this paper are based on original analysis of transport of dopant with account transport and interaction of radiation defects.

Multilevel inverters play a major role in the development of high-power industrial applications. In traditional low-level inverters (e.g. 2-level), the switching frequency is restricted and the harmonic spectrum of the system is hard to meet power requirements. Similarly, high-level inverters consist of a large number of switches, complex modulation techniques and complex hardware architecture, which results in high power loss and a significant amount of harmonic distortion. Furthermore, it is a must to ensure that every switch experiences the same stress of voltage and current. The purpose of this paper is to present an inverter topology with lower conduction and switching losses via reduced number of switches and equal voltage source-sharing technique.

Herein, the authors present a cascaded multilevel inverter having less power switches, a simple modulation technique and an equal voltage source-sharing phenomenon implementation.

The modulation technique becomes more complex when equal voltage source-sharing is to be implemented. In this study, a novel topology for the multilevel inverter with fewer switches, novel modulation technique, equal voltage source-sharing and Inductor-Capacitor-Inductor filter implementation is demonstrated to the reduce harmonic spectrum and power losses of the proposed system.

The nine-level inverter design is validated using software simulations and hardware prototype testing; the power losses of the proposed inverter design are elaborated and compared with the traditional approach.

This paper aims to propose a new configuration of a shunt active power filter (SAPF) connected with a photovoltaic (PV) system through a Z-source inverter (ZSI) topology. This topology ensures a single-stage operation and overcomes the limitations of the conventional two-stage operation topologies based on the DC–DC boost converter. The proposed system is designed for the purpose of reducing the total harmonic distortion of the source current by eliminating the current harmonics and exploiting the solar irradiation.

First, all the main parts of the proposed shunt active power filter are fully described in this paper, and then a PV system based on a Z-source inverter with a maximum power point tracking controller is used to exploit the solar irradiance and solve the problem of discharging of the direct current (DC) capacitor during the filtering process.

From the extensive simulation tests carried out using MATLAB/Simulink, the obtained results prove that the proposed shunt active power filter performs well despite several operation scenarios, including different load types and under abrupt irradiance.

A new shunt active power filter configuration has been proposed. This configuration benefits from the solar irradiation and overcomes the drawbacks of the conventional configurations by using the Z-source inverter instead of the voltage source inverter and DC–DC boost converter.

This paper is devoted to the investigation of the potentialities of induction motor DTC strategies in position control applications.

A comparison study is carried out between two DTC strategies dedicated to position control applications such as robotic: the Takahashi DTC strategy where the induction motor is fed by a two‐level inverter and a new DTC strategy where the induction motor is fed by a three‐level inverter. Special attention is paid to the synthesis of the vector selection table of the second strategy in an attempt to guarantee a high dynamic with reduced ripple of the torque. The comparison study is achieved considering four performance criteria: phase current total harmonic distortion; inverter switching loss factor; quality factor; and inverter commutation frequency.

It has been found that the introduced DTC strategy offers higher performance than the Takahashi one. Of particular interest are: the reduction of both torque ripple and commutation frequency; the eradication of the demagnetization problem which is a vital requirement in position control applications; and the improvement of the power factor thanks to which a reduction of the inverter rating is gained.

This work should be extended considering the validation of the obtained simulation results through experiments.

The paper proposes a new DTC strategy dedicated to position control applications. It allows the elimination of the demagnetization problem from which suffers the Takahashi DTC strategy at low speeds especially at zero speed in position control applications. It also offers a high power factor which opens up crucial cost benefits as far as the inverter rating is concerned.