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This paper aims to present an analysis of a hybrid high‐voltage switch based on the parallel connection of IGBT and IGCT. The proposed configuration combines the advantages of both semiconductors, resulting in substantially reduced power losses. Such energy efficient switches could be used in high‐power systems where the requirements of high switching frequency or decreased cooling systems are a major concern.

The operation principle of the switch is described and simulated. The power dissipation is estimated at different operation conditions. Further, the implementation possibilities of the proposed switch configuration in a three‐level NPC inverter are analysed. The operation with the proposed PWM control algorithm is simulated and inverter power loss distribution is estimated.

According to estimations, the proposed hybrid switch configuration allows the reduction of total losses in semiconductors by at least 50 percent. If two of these switches are used in a three‐level NPC inverter as outer switches, the total losses of the inverter are reduced by 27 percent, at the same time the losses in the most stressed semiconductor device are reduced by a factor of 2.25. Therefore, achieving higher power density is possible.

The proposed switch configuration is intended for high‐power (>500 KVA) industrial, marine and railway traction systems, such as FACTS and high power variable frequency AC drives.

The paper presents the novel energy‐efficient high‐voltage switch based on the parallel connection of commercially available IGBTs and IGCTs.

This paper aims to propose a new transformer-less inverter structure to reduce the common-mode leakage current in grid-connected photovoltaic (PV) systems.

The proposed circuit structure is the same as the conventional full-bridge inverter with three additional power switches in a triangular structure. These three power switches are between the bridge and the output filter, and they mitigate the common-mode leakage current flowing toward the PV panels’ capacitors. The common-mode leakage current mitigation is done through the three-direction clamping cell (TDCC) concept. By clamping the common-mode voltage to the middle voltage of the DC-link capacitors, the leakage current and the total harmonic distortion (THD) of the injected current to the grid is effectively reduced. Therefore, the efficiency is improved.

The switching modes and the control method are introduced. A comparison is carried out between the proposed structure and other solutions in the literature. The proposed topology and its respective control method are simulated by PSCAD/EMTDC software. The simulation results validate the advantages of the presented structure such as clamping the common-mode voltage and reducing leakage current and THD of injected current to the grid.

Presenting a single phase-improved inverter structure with low-leakage current for grid-connected PV power systems represents a significant original contribution to this work. The proposed structure can inject a sinusoidal current with low THD to the AC grid, and the power factor is unity on the AC side. In the half positive cycle, one of the switches in the TDCC is turned off under zero current. Besides, one of the other switches in TDCC is turned on with zero voltage and, therefore, its turn-on switching losses are zero. The efficiency of the proposed topology is high because of the reduction of leakage current and power losses. Accordingly, the presented topology can be a good solution to the leakage current elimination.

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 present an 8 kW LLC resonant converter designed for plasma power supply with higher efficiency and lighter structure. It presents how to solve the problems of large volume and weight, low performance and low efficiency of traditional plasma power supply.

At present, conventional silicon (Si) power devices’ switching performance is close to the theoretical limit determined by its material properties; the next-generation silicon carbide (SiC) power devices with outstanding advantages can be used to optimal design. This 8 kW LLC resonant converter prototype with silicon carbide (SiC) power devices with a modulated switching frequency ranges from 100  to 400 kHz.

The experimental results show that the topology, switching loss, rectifier loss, transformer loss and drive circuit of the full-bridge LLC silicon carbide (SiC) plasma power supply can be optimized.

Due to the selected research object (plasma power supply), this study may have limited universality. The authors encourage the study of high frequency resonant converters for other applications such as argon arc welding.

This study provides a practical application for users to improve the quality of plasma welding.

The experimental results show that the full-bridge LLC silicon carbide (SiC) plasma power supply is preferred in operation under conditions of high frequency and high voltage. And its efficiency can reach 98%, making it lighter, more compact and more efficient than previous designs.

This paper aims to focus on the trade-off between losses and converter cost.

The continual development of power electronic converters, for a wide range of applications such as renewable energy systems (interfacing photovoltaic panels via power converters), is characterized by the requirements for higher efficiency and lower production costs. To achieve such challenging objectives, a computer-aided design optimization based on genetic algorithms is developed in Matlab environment. The elitist non-dominated sorting genetic algorithm is used to perform search and optimization, whereas averaged models are used to estimate power losses in different semiconductors devices. The design problem requires minimizing the losses and cost of the boost converter under electrical constraints. The optimization variables are, as for them, the switching frequency, the boost inductor, the DC capacitor and the types of semiconductor devices (IGBT and MOSFET). It should be pointed out that boost topology is considered in this paper but the proposed methodology is easily applicable to other topologies.

The results show that such design methodology for DC-DC converters presents several advantages. In particular, it proposes to the designer a set of solutions – as an alternative of a single one – so that the authors can choose a posteriori the adequate solution for the application under consideration. This then allows the possibility of finding the best design among all the available choices. Furthermore, the design values for the selected solution were obtainable components.

The authors focus on the general aspect of the discrete optimization approach proposed here. It can also be used by power electronics designers with the help of additional constraints in accordance with their specific applications. Furthermore, the use of such non-ideal average models with the multi-objective optimization is the original contribution of the paper and it has not been suggested so far.

Votage source converter (VSC) based or current source converter (CSC) based shunt active power filter (SAPF)? It is the main question in harmonic elimination project using SAPF.This paper presents some criteria based on which the designer can decide which type of filter is more suitable for implementation of the project according to the nature and characteristics of the project.

Owing to the importance of cost and power losses criteria, relevant equations will be formulated and comparative analysis will be carried out between conventional structures based on CSC or VSC. For validation of analyses, simulation results have been studied in the MATLAB–SIMULINK environment.

Simulation results have examined two important criteria of power losses and costs. Although the results show the superiority of VSSAPF to CSSAPF in both criteria, this comparison is performed in a general and conventional condition. Using third-order filters of inductive-capacitive-inductive (LCL) type in VSSAPF, using insulated-gate bipolar transistor (IGBT) with reverse-voltage blocking ability in CSSAPF, which eliminates the need to use series diodes, and the use of superconducting technology in the DC-side endpoint in CSSAPF, not only reduce the difference of cost and losses in two schemes but also may lead to the lower costs and losses in CSSAPF than VSSAPF.

This paper is the result of many years working on active power filter and can be useful for engineers who are engaged in industrial projects.

The purpose of this paper is to examine the moderator effects of switching costs, classified by type (relational, procedural, and financial) and direction (positive and negative), on the relationships between customer-perceived value, trust, and loyalty.

This study reports on quantitative data from a survey of two service contexts which vary in their degree of customer-employee contact and customization. In total, 360 usable questionnaires were collected, and the data were analyzed using multi-group structural equation modeling.

The results demonstrate that switching costs moderate, in different ways, the relationships between customer loyalty, trust and perceived value. Moreover, the strength of the moderator effects vary according to service type.

This study provides new insight into understanding the moderating role of switching costs thus, reduces inconsistencies about the direction and the strength of the moderator effect of switching costs in loyalty frameworks.

This study helps managers choose the most effective loyalty strategy for specific service industries and perceptions of switching costs, and to look beyond their service boundaries in order to cross-fertilize strategies for handling switching costs.

No empirical study to date has simultaneously examined the moderator effect of switching costs classified by type and direction on the relationships between customer-perceived value, trust, and customer loyalty across two different service contexts in a single framework.

Maintaining a balanced neutral point, reducing power loss, execution time are important criteria for the controlling of neutral point clamped (NPC) inverter. However, it is tough to meet all the challenges and also supplying the load current within the harmonic limit. This paper aims to maintain load current quality within the Institute of Electrical and Electronics Engineers 519 standard and meet the above-mentioned challenges.

The output load current of a three-level simplified neutral point clamped (3 L-SNPC) inverter is controlled in this paper using model predictive control (MPC). The 3 L-SNPC inverters is considered because fewer semiconductor devices are used in this topology; this will enhance the reliability of the system. MPC is used as a controller because it can handle the direct current-link capacitors’ voltage balancing problem in a very intuitive way. The proposed 3 L-SNPC yields similar current total harmonic distortion (THD), transient and steady-state responses, voltage stress and over current protection capability as the conventional NPC inverter. To reduce the computational burden of the proposed SNPC system, two simplified MPC strategies are proposed, namely, single voltage vector prediction-based MPC and selective voltage vector prediction-based MPC.

The system shows a current THD of 2.33% at 8.96 kHz. The overall loss of the system is reduced significantly to be useful in medium power applications. The required execution times for the simplified MPC strategies are tested on the hardware dSPACE 1104 platform. It is found that the single voltage vector prediction-based MPC and the selective voltage vector prediction-based MPC are computationally efficient by 8.28% and 62.9%, respectively, in comparison with the conventional MPC-based conventional NPC system.

Multiple system constraints are considered throughout the paper and also compare the SNPC to the conventional NPC inverter. Proper current tracking, over-current protection, overall power loss reduction especially switching loss and maintaining capacitor voltages balance at a neutral point are achieved. The improvement of execution time has also been verified and calculated using hardware-in-loop of the dSPACE DS1104 platform.

The purpose of this paper is to present, a novel boost‐active clamp bridge single stage high‐frequency zero voltage soft‐switching‐pulse width modulation (ZVS‐PWM) inverter, which converts the utility frequency AC power into high‐frequency AC power with an embedded controller. This single stage high‐frequency inverter is composed of a single‐phase diode bridge rectifier, a non‐smoothing filter, a boost‐active clamp bridge type ZVS‐PWM high‐frequency inverter, and an induction‐heated load with planar type litz wire working coil assembly. Also, the paper discusses how to extend the soft‐switching operation ranges and improve power conversion efficiency.

The proposed converter is simulated and it is implemented using embedded controller.

It was found that the single stage high‐frequency induction heating (IH) inverter using boosted voltage function can eliminate the DC and low‐frequency components of the working coil current and reduce the power dissipation of the circuit components and switching devices.

The paper shows that the PWM HF inverter is preferred for IH, since it has reduced switching losses and switching stresses. The paper can be extended to PC‐based wireless control, which can be part of a distributed control system in major industrial heating systems.

The purpose of this paper is to trace the behaviour of Chinese companies receiving a special treatment (ST) designation in order to determine the extent to which the application of this regulation may have led companies to engage in activities conducive to the removal of the ST designation. In particular, the paper examines evidence of opinion shopping or earnings manipulation by these companies.

Empirical analysis of annual report databases for Chinese‐listed companies, including statistical significance testing relating to ST companies.

Most ST companies have removed the ST status by the third year after the initial ST designation. Compared to non‐ST companies, ST companies losing the ST status are more likely to engage in practices indicating earnings manipulation. Also, compared to non‐ST companies, ST companies are more likely to change auditors after an initial or second year of ST designation. However, while this behaviour suggests opinion shopping, auditor switching for the ST companies is not associated with losses becoming profits nor with improved audit opinions.

The results reported in this paper must be considered in light of the limitations inherent in empirical analyses. That is, the relationships identified in this paper are indicative of potential earnings management or audit opinion shopping; however, the study cannot provide the actual reasons for these empirical results.

The results suggest the ST regulation did not lead to unintended consequences in terms of auditor switching by ST companies to improve either their reported earnings or their audit opinion.

The ST status is unique to China and this paper is the first to report on potential reporting and audit quality implications of this regulation.