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Decarbonization is driving power systems toward more decentralized, self-governing models. While these technologies improve efficiency, planning, operations, and reduce the carbon footprint, they also introduce new challenges. In modern grids, particularly with the integration of power electronic devices and high penetration of Renewable Energy Sources (RES) and Inverter-Based Resources (IBRs), traditional reliability concepts may no longer ensure adequate performance due to systemic restructuring. This shift necessitates new or significantly modified reliability indices to capture the characteristics of the evolving power system. Ensuring converter reliability is essential for effective planning, which requires precise, component-to-system-level modeling, as different converters impact system performance indicators. However, the existing literature in this field faces a significant limitation, as most studies focus on a singular perspective. Some examine reliability at the device-level, others at the component-level, while broader reviews in power systems often emphasize system-level analysis. In this paper, we aim to bridge these gaps by comprehensively reviewing the interconnections between these levels and analyzing the mutual influence of power converter and system reliability. A key point to highlight is that, with the rapid evolution of modern power grids, decision-makers must adopt a multi-level approach that incorporates insights from all levels to enable more accurate and realistic planning and operational strategies. Our ultimate goal is to provide an in-depth investigation of studies addressing the unique challenges posed by modern power grids. Finally, we will highlight the gaps in the literature and suggest directions for future research. [ABSTRACT FROM AUTHOR]

In this article, the linear non-equilibrium thermodynamic approach is used to mathematically describe the energy regularities of an interior permanent magnet synchronous motor (IPMSM), taking into account iron loss. The IPMSM is considered a linear power converter (PC) that is multiple-linearized at operating points with a given angular velocity and load torque. A universal description of such a PC by a system of dimensionless parameters and characteristics made it possible to analyze the perfection of energy conversion in the object. For IPMSM, taking into account iron loss, a mathematical model of the corresponding PC has been built, and an algorithm and research program have been developed, which is valid in a wide range of machine speed regulations. This allows you to choose the optimal points of PC operation according to the maximum efficiency criteria and obtain the efficiency maps for IPMSM in different speed regions. The results of the studies demonstrate the effectiveness of the proposed method for determining the references of the d and q components of the armature current for both the loss-minimization strategy at the constant torque range of motor speed and the flux-weakening strategy in the constant power range. [ABSTRACT FROM AUTHOR]

This article presents a detailed analysis of a previously introduced boost converter based on cascaded capacitor connections. The analyzed converter maintains the same voltage gain as its conventional double-boost converter counterpart. The main advantage of the redesigned converter is that it requires smaller capacitors, rated to a lower voltage, due to the cascaded connection. This makes it suitable for various applications, including distributed generation and microgrids. This paper conducts the mathematical modeling of the converter with large signal models and the equilibrium operation in continuous conduction mode, employed to implement a control scheme. Even though the individual capacitor voltage ripple reaches high values, for voltage gains above five, the output voltage ripple is lower compared with that of other converters. The analysis also includes a comparative study with the conventional double dual boost converter. Simulations assess the proposed topology's ability to effectively minimize the switching ripple in the output voltage, even with smaller capacitors. Finally, experimental results are also provided to confirm the functionality of the proposed converters under various operational conditions, which confirm its suitability for low-voltage generator applications. [ABSTRACT FROM AUTHOR]

The increasing demand for wireless power transfer (WPT) systems for electric vehicles (EVs) has necessitated advancements in charging solutions, with a particular focus on speed and efficiency. However, power transfer efficiency is the major concern in static and dynamic wireless charging (DWC) design. Design consideration and improvements in all functional units are necessary for an increase in overall efficiency of the system. Recently, different research works have been presented regarding DWC at the power converter, coil structure and compensators. This paper provides a comprehensive review of power converters incorporating high-order compensation topologies, demonstrating their benefits in enhancing the DWC of EVs. The review also delves into the coupling coil structure and magnetic material architecture, pivotal in enhancing power transfer efficiency and capability. Moreover, the high-order compensation topologies used to effectively mitigate low-frequency ripple, improve voltage regulation, and facilitate a more compact and portable design are discussed. Furthermore, optimal coupling and different techniques to achieve maximum power transfer efficiency are discussed to boost magnetic interactions, thereby reducing power loss. Finally, this paper highlights the essential role of these components in developing efficient and reliable DWC systems for EVs, emphasizing their contribution to achieving high-power transfer efficiency and stability. [ABSTRACT FROM AUTHOR]

Microgrids are designed to connect different types of AC and DC loads, which require robust power controllers to achieve an efficient power transfer. However, the effects of both AC and DC disturbances in the same type of controller make achieving stability a design challenge, especially in coupled systems where disturbances affect both the upstream and downstream in the microgrid. This paper presents an analysis of a second-order sliding-mode control (SOSMC) applied to a microgrid with direct-current (DC) and alternating-current (AC) power converters. The aim is to simulate the second-order sliding-mode control with buck converters that feed constant DC–DC and DC–AC power loads. The controller was tested in consideration of a unique sliding surface facing external disturbances, such as variations in the frequency of AC converters, sudden changes in upstream voltages, and constant power loads (CPL). The influence of the gain values (K) on the controller was also analyzed. The results show that the controller is robust regarding its sensitivity to external disturbances and steady-state error. However, the importance of the constant "K" in the model states that there exist K-limit values where if "K" is too low, a slowdown is presented, and the response against disturbances can be critical, and if is too high, an overshoot is presented in the output voltage. [ABSTRACT FROM AUTHOR]

Three LED drivers which can be used for illumination, but whose main task is the transmission of information (data) via the light of the LEDs, are explored in this paper. The converter circuits need no capacitors for the energy transformation and avoid an inrush current. The lack of necessity of electrolytic capacitors reduces cost and space. Dimming the illumination is also easy to achieve. The control concept of the converters and the generation of pulsing of the LEDs for transmitting the information (data) are explained. The converters can also be expanded to more stages to drive more LEDs with different types of information. All three converters are explained in detail; all presented circuits are built up and simulated with LTSpice. Several data transmission concepts are applied and demonstrated through simulations. [ABSTRACT FROM AUTHOR]

This paper presents an examination regarding the DC–DC converter output behavior at variable loads. An example of a circuit with two-quadrant operation with different control methods is shown. The presented mathematical approach is used to determine the main output values and could have an enclosure as the calculation methodology. The examination data for the step-down circuit configuration with a single-ended output LC filter are provided. A modified excel model is used to extract the parameters for the circuit output gain at the rated frequency. The simulations of the load factor variation are shown in four different plots, where the area of the steady operation is presented. The results are derived to estimate the relationship between the circuit output and load characteristics' deviation. The converter dynamic range of the operation is determined by the presented graphics. A proper LC output filter design is essential for reducing the ripple currents and increasing the overall circuit effectivity. [ABSTRACT FROM AUTHOR]

This paper proposes an improved zero-current distortion compensation (IZCDC) method for the Vienna rectifier. The conventional zero-current distortion compensation (ZCDC) method modifies the reference voltages by adding an offset voltage to compensate for the zero-current distortion (ZCD). However, the reference voltages occasionally exceed the linear modulation region by the offset voltage added at the driving start-point of the Vienna rectifier, where the modulation index of phase voltage is relatively large. This causes a hard-start of the Vienna rectifier accompanied by a serious surge and distortion in the phase current. In this paper, the IZCDC method is proposed for achieving the soft-start of the Vienna rectifier. When the overmodulation occurs, the proposed method modifies the conventional offset voltage to the IZCDC component, which is involved in the adjustment of the variance of the phase current, only for a certain phase among the three phases. As the IZCDC component regulates the variance of the phase current to zero, surge and distortion in the phase current can be mitigated. As a result, the Vienna rectifier starts its operation softly while ensuring its normal operation in the transients. The effectiveness of the proposed method is verified through simulations and experimental results. [ABSTRACT FROM AUTHOR]

The junction temperature of a power device in a natural air-cooled power converter fluctuates randomly due to the variation in airflow rate in ambient environments. Most of the existing thermal analysis methods do not pay attention to the uncertain influence of airflow on the heat-dissipation capacity of such converters, making it difficult to accurately evaluate the thermal safety of these devices. To address this issue, a thermal safety assessment method for power devices in natural air-cooled converters is proposed in this paper. In the proposed method, convective heat resistance samples of converter housing are extracted with an equivalent thermal network model and the historical operation temperature of the converter. Wavelet packet transform is used to analyze the time–frequency domain characteristics of the convective heat resistance, and Monte Carlo simulation is employed to simulate the random influence of the airflow rate on the device junction temperature. The thermal safety of power devices is assessed in the form of over-temperature probability, which is expressed by a two-variable growth function. An experimental platform is designed to validate the effectiveness of the proposed method. The results show that the proposed method can accurately estimate the over-temperature risk of a power device in a natural air-cooled converter under different ambient temperature and current levels, thus effectively improving the thermal reliability of converters. [ABSTRACT FROM AUTHOR]

This research explores an improved operation of a recently studied converter, the so-called two-phase sixth-order boost converter (2P6OBC). The converter consists of a symmetric design of power stations followed by an LC filter; its improved operation incorporates an asymmetric pulse width modulation (PWM) scheme for transistor switching, sometimes known as an interleaved PWM approach. The new operation leads to improved performance for the 2P6OBC. Along with studying the 2P6OBC, one of the contributions of this research is providing design equations for the converter and comparing it versus the interleaved (or multiphase) boost converter, known for its competitiveness and advantages; the single-phase boost topology was also included in the comparison. The comparison consisted of a design scenario where all converters must achieve the same power conversion with an established maximum switching ripple, and then the stored energy in passive components is compared. Although the 2P6OBC requires a greater number of components, the total amount of stored energy is smaller. It is known that the stored energy is related to the size of the passive components. Still, the article includes a discussion of this topic. The new operation of the converter offers more streamlined, cost-effective, and efficient alternatives for a range of applications within power electronics. The final design of the 2P6OBC required only 68% of the stored energy in inductors compared to the multiphase boost converter, and 60% of the stored energy in capacitors. This result is outstanding, considering that the multiphase boost converter is a very competitive topology. Experimental results are provided to validate the proposed concept. [ABSTRACT FROM AUTHOR]

A three-phase multilevel inverter (MLI), synthesized with 31 levels in regard to its output voltage, is used to provide the AC supply to a three-phase, squirrel cage induction motor. The gating angles required for the 30 power switches on the MLI are optimized using both the genetic algorithm (GA) and the grey wolf optimizer (GWO), in which the optimal angles are determined through solving the trigonometric equations taken from Fourier analysis to target the minimum total harmonic distortion (THD) at the MLI output. A simulation model and an experimental prototype are developed for performance analysis and validation. The results demonstrate that the MLI is effectively able to produce 31 levels of three-phase AC output voltage, with the THD not exceeding 5% when loaded with a resistive load and a three-phase induction motor. The voltage and current are measured and recorded for different loads and operating conditions, including the amount of energy consumed by the load. The results of the frequency analysis demonstrate that most of the triple harmonics, which can harm the efficiency of the inverter, are cancelled. [ABSTRACT FROM AUTHOR]

Power converters can convert the electrical energy output by power source into specific forms required by target device. They are widely used in various fields such as electrification, transportation, and power systems, and are the core components of the systems. Power converters are composed of power semiconductor devices (such as IGBTs), which are prone to failure due to abnormal conditions and aging degradation, leading to power converter faults. Therefore, over the past twenty years, extensive fault diagnosis methods for power converters have been studied and proposed. Among them, symmetry-based methods have the characteristics of rapid diagnosis speed and strong robustness, but so far there's no systemic summary of such methods. Therefore, this paper reviews the relevant research on fault diagnosis of power converters based on symmetry in recent years, analyzes the mathematical principles of these methods, and compares their diagnostic performance. In addition, two factors that may have an influence on the symmetry are pointed out. This paper provides references and suggestions for the future development and research of power converter fault diagnosis. [ABSTRACT FROM AUTHOR]

Fast switching within static converters is a key to high-efficiency operation and a source of electromagnetic disturbances that can harm the proper functioning of the converters themselves or the electronic equipment placed in their neighborhood. To characterize disturbances, engineers are mainly focused on the spectral content since the higher the switching speed, the more important the high-frequency components are. In this article, a figure of merit (FOM) independent of switching speed is proposed. It allows us to compare switching patterns produced by a gate driver to each other, using as a reference the mathematical optimum of a Gaussian pattern as well as other elementary forms for which the FOM is known. A complete implementation methodology is presented to properly use this FOM that considers an adapted sampling frequency and filtering of signals before processing in order to correctly obtain information for the optimal adjustment of a driver. [ABSTRACT FROM AUTHOR]

This article presents a new modulation technique called three-dimensional sigma–delta (3D- Σ Δ ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D- Σ Δ technique enables operation at a variable switching frequency, resulting in a significant reduction in switching losses compared to classical pulse-width modulation (PWM) techniques. Moreover, the 3D- Σ Δ technique uses a fast-processing 3D quantiser that simplifies implementation and considerably reduces computational costs. The behaviour of the 3D- Σ Δ modulation is analysed using MATLAB/Simulink and PLECS. The experimental results performed on an active power filter that uses silicon carbide (SiC) MOSFETs demonstrate an improvement in converter efficiency compared to the conventional SPWM technique. Additionally, the experimental results show how 3D- Σ Δ allows for the compensation of harmonics and homopolar currents, thereby balancing the electrical grid currents. The experiments also show that the proposed 3D- Σ Δ modulation outperforms an SPWM technique in terms of power quality, since the former achieves a larger reduction in the harmonic content of the power grid. In conclusion, the proposed modulation technique is an attractive option for improving the performance of four-wire converters in active power filter applications. [ABSTRACT FROM AUTHOR]

The utilization of fuel cells (FC) in automotive technology has experienced significant growth in recent years. Fuel cell hybrid electric vehicles (FCHEVs) are powered by a combination of fuel cells, batteries, and/or ultracapacitors (UCs). By integrating power converters with these power sources, the FCHEV system can overcome the limitations of using them separately. The performance of an FCHEV is influenced by the efficiency of the power electronics converter controller, as well as the technical efficiency of the power sources. FCHEVs need intricate energy management systems (EMSs) to function effectively. Poor EMS can lead to low efficiency and accelerated fuel cell and battery degradation. The literature discusses various types of EMSs such as equivalent consumption minimization strategy, classical PI controller, fuzzy logic controller, and mutative fuzzy logic controller (MFLC). It also discusses a systematic categorization of FCHEV topologies and delves into the unique characteristics of these topologies. Furthermore, it provides an in-depth comparative study of EMSs applied in FCHEVs, encompassing rule-based, optimization-based, and advanced learning-based approaches. However, comparing different EMSs can be challenging due to the varying vehicle and system parameters, which might lead to false claims being made regarding system performance. This review aims to categorize and discuss the various topologies of FCHEVs, highlighting their pros and cons, and comparing several EMSs based on performance metrics such as state of charge (SOC) and FC deterioration. This paper seeks a deeper comprehension of the recent advancements in EMSs for FCHEVs. It offers insights that can facilitate a more comprehensive grasp of the current state of research in this field, aiding researchers in staying up to date with the latest developments. [ABSTRACT FROM AUTHOR]

In modern converter-dominated power systems, total inertia is very variable and depends on the share of power generated by renewable-based converter-interfaced generation (CIG) at each specific moment. As a result, the limits required by the grid codes on the rate of change of frequency and its nadir or zenith during disturbances become challenging to achieve with conventional control approaches. Therefore, the transition to a novel control strategy of CIG with a grid-forming power converter is relevant. For this purpose, a control algorithm based on a virtual synchronous generator (VSG) is used, which simulates the properties and capabilities of a conventional synchronous generation. However, due to continuously changing operating conditions in converter-dominated power systems, the virtual inertia formed by VSG must be adaptive. At the same time, the efficiency of adaptive algorithms strongly depends on the used VSG structure. In this connection, this paper proposes an enhanced VSG structure for which the transfer function of the active power control loop was formed. With the help of it, the advantages over the conventional VSG structure were proven, which are necessary for the effective adaptive control of the VSG parameters. Then, the analysis of the impact of the VSG parameters on the dynamic response using the transient characteristics in the time domain was performed. Based on the results obtained, adaptive algorithms for independent control of the virtual inertia and the parameters of the VSG damper winding were developed. The performed mathematical modeling confirmed the reliable and effective operation of the developed adaptive control algorithms and the enhanced VSG structure. The theoretical and experimental results obtained in this paper indicate the need for simultaneous development and improvement of both adaptive control algorithms and VSG structures used for this purpose. [ABSTRACT FROM AUTHOR]

This paper presents the minimization of total harmonic distortion in a seven-level cascaded H-bridge multilevel inverter with resistive load using the teaching–learning-based optimization algorithm. The minimization of Total Harmonic Distortion (THD)is a challenging optimization problem due to the fact that nonlinear equations are involved. Recently, bio-inspired algorithms have become very popular approaches to solving various optimization problems in different areas of engineering. For this reason, the results obtained with the Teaching–Learning-Based Optimization (TLBO)algorithm were compared with three other popular bio-inspired algorithms, the genetic algorithm, differential evolution, and particle swarm optimization. The comparative analysis, conducted by sweeping the modulation index, made it possible to obtain graphs and data on the behavior of the four analyzed algorithms. Finally, it was concluded that the TLBO algorithm is very effective and is able to solve the THD-minimization problem. Its main advantage over the other algorithms is the fact that it does not require control parameters for its correct operation in the solution of the problem. [ABSTRACT FROM AUTHOR]

The purpose of this research is to present a thorough evaluation of energy management systems that consist of hybrid energy storage systems and their control algorithms, which may be used in electric vehicles. This paper outlines the characteristics of electric vehicles, research methods, an analysis of the hybrid energy storage system architecture, the converter topology, and energy management techniques. The strength and co-occurrence of keywords over the past ten years are shown in this study using a systematic research framework for performing a literature review and using keyword analysis techniques. This study reveals a pattern of recently and frequently used terms in works of literature. Consequently, their suitability, benefits, and drawbacks are assessed. In this study, the hybrid energy storage system and converter circuit architecture are evaluated and rated. A non-isolated DC-DC converter connected to an SC is a suitable configuration for the hybrid converter because it is simple to build, is reliable, and has minimal loss/weight/cost, which all improve vehicle performance. In terms of the application of control strategies, it is shown that deterministic and fuzzy-rule-based control techniques are successfully assessed using real-scale vehicle experiments and can be selected for manufacturing. On the other hand, real-time optimization-based energy management techniques have been effectively shown in lab-scale tests and may be used in a future real-scale vehicle. [ABSTRACT FROM AUTHOR]

The multilevel inverter (MLI) has been developed as a powerful power conversion scheme for several processes, including renewable energy, transmission systems, and electric drives. It has become popular across medium- to high-power operations due to its many advantages, including minimum harmonic content, low switching losses, and reduced electromagnetic interference (EMI). In this paper, the capacitor voltage balancing technique-based pulse width modulation (PWM) has been proposed. The proposed PWM strategy offers several advantages, such as high-quality output waveforms with reduced harmonic distortion, improved efficiency, and better control over the output voltage. The Xilinx ISE 10.1 software was used for synthesizing, and the VHDL code was written for the proposed method. MATLAB software was used to simulate and hardware was used to verify the proposed system. The SPARTAN 3E FPGA was used for the generation of the PWM. This paper developed a 2 kW single-phase 15-level inverter that created an AC wave from the DC input voltage, with a total harmonic distortion (THD) of 8.02%, which was less than the THD achieved from other conventional MLI. The results indicate that MLI topologies with low total harmonic currents, fewer switches, and higher output voltage levels are better stabilized during load disturbance circumstances. [ABSTRACT FROM AUTHOR]

In response to the rapid changes in the international energy environment, developing renewable energy (RE)-based distributed generation (DG) and various smart micro-grid systems is crucial for creating a robust electric power grid and new energy industries. In this aspect, there is an urgent need to develop hybrid power systems suitable for coexistent AC and DC power grids, integrated by high-performance wide ban gap (WBG) semiconductor-based power conversion interfaces and advanced operating and control strategies. Due to the intrinsic feature of variation in RE-based power generation, the design and integration of energy storage devices, real-time regulation of power flow, and intelligent energy control schemes are key technologies for further promoting DG systems and micro-grids. This paper investigates an integrated control scheme for multiple GaN-based power converters in a small- to medium-capacity, grid-connected, and RE-based power system. This is the first time that a complete design case demonstrating three GaN-based power converters with different control functions integrated with a single digital signal processor (DSP) chip to achieve a reliable, flexible, cost effective, and multifunctional power interface for renewable power generation systems is presented. The system studied includes a photovoltaic (PV) generation unit, a battery energy storage unit, a grid-connected single-phase inverter, and a power grid. Based on system operation condition and the state of charge (SOC) of the energy storage unit, two typical operating modes and advanced power control functions are developed with a fully digital and coordinated control scheme. Hardware of the GaN-based power converters and digital controllers are designed and implemented. The feasibility and effectiveness of the designed controllers and overall performance of the proposed control scheme are verified with results from simulation and experimental tests on a 1-kVA small-scale hardware system. [ABSTRACT FROM AUTHOR]

This work evaluates the impact of the input voltage noise on a Hardware-In-the-Loop (HIL) system used in the emulation of power converters. A poor signal-to-noise ratio (SNR) can compromise the accuracy and precision of the model, and even make certain techniques for building mathematical models unfeasible. The case study presents the noise effects on a digitally controlled totem-pole converter emulated with a low-cost HIL system using an FPGA. The effects on the model outputs, and the cost and influence of different hardware implementations, are evaluated. The noise of the input signals may limit the benefits of increasing the resolution of the model. [ABSTRACT FROM AUTHOR]

Electric vehicles (EVs) integrate two main power electronics systems, namely, the battery charging system and the traction system. In this study, we aimed to complement and deepen the study of the latter, more specifically, focusing on a traction system based on a synchronous reluctance permanent magnet (SRPM) machine, since this is an emerging electric machine in the EV paradigm. The developed prototype integrates bidirectional ac-dc and dc-dc converters, allowing for regenerative braking, and the SRPM machine is controlled using a maximum torque per ampere (MTPA) algorithm. Computer simulations and the experimental results for the traction system are presented in this paper. The dynamic characteristics of the SRPM machine proved to be relevant for EV applications, with effective results obtained during load and speed changes. The effective behavior of the SRPM machine was partially rooted in the use of the MTPA algorithm, which has proven itself to be an effective algorithm for the electric machines of EVs. [ABSTRACT FROM AUTHOR]

Low-voltage photovoltaic systems are being widely used around the world, including their introduction into the power grid. The development of these systems requires the adaptation of several power converters, their static and dynamic modeling, the design of passive elements, and the design of the controller parameters, among other actions. Today, power converters are key elements in the development of photovoltaic systems, and classical power converters such as buck converters produce discontinuous input and output currents, requiring a high input capacitance and impacting the output power quality of these systems. This paper presents a proposal for a low-voltage photovoltaic system that uses a continuous input/output current buck converter, which enhances the operation of the classical buck converter in photovoltaic systems. The methodology describes the proposed photovoltaic system, including the power converter, its detailed operation, and the analysis of its waveforms. Moreover, the methodology includes a mathematical model of the photovoltaic system's dynamic behavior and the design of a sliding-mode controller for maximum power extraction and perturbation rejection. The photovoltaic system is validated in two ways: first, a comparison with the classical buck converter highlighting the advantages of continuous input/output currents is presented; then, an application example using commercial devices is described in detail. The application example uses a flowchart to design the power converter and the sliding-mode controller, and a circuit simulation confirms the advantages of the continuous input/output current buck converter with its controller. In the circuit simulation, the control strategy is formed by a perturb and observe algorithm that generates the voltage reference for the sliding-mode controller, which guarantees the system stability, tracks the maximum power point, and rejects the double-frequency oscillations generated by an intended microinverter. [ABSTRACT FROM AUTHOR]

This article introduces a single-phase five-level multilevel inverter based on six switches and two transformers. The proposed converter requires a single dc input source with low voltage. The disposition of switches makes it possible to build the converter with a transistors six-pack module off-the-shelves, traditionally used to build three-phase inverters, which simplifies the manufacturing process. The converter increases the voltage with two transformers; for that reason, it does not require an auxiliary step-up converter. The use of transformers (with the transformer's turns ratio) allows for using the same topology for several input voltage levels. To verify the operation of the proposed multilevel inverter, a computer-based simulation was performed with PSIM, a software that considers parasitic components. The results show that the proposed converter can work properly. [ABSTRACT FROM AUTHOR]

In recent years, micro turbine technology has become a continuously reliable and viable distributed generation system. The application of distributed energy power generation sources, such as micro gas turbines (MGT), to charge electric vehicles offers numerous technical, economical benefits, and opportunities. MGT are considered as they are smaller than conventional heavy-duty gas turbines. They also are capable of accepting and operating with different fossil fuels in the range of low–high pressure levels as well as co-generation opportunities. The MGT could provide the fast and reliable output power guaranteed and needed for grid stability. This paper provides a mathematical representation, modelling, and simulation of a low-cost fast charging station based on a micro gas turbine and a super capacitor forming altogether a power generation system suitable for use especially as energy source in fast charging stations and dynamic power systems. All the micro gas turbine's parameters are estimated according to available performance and operational data. The proposed system generates up to 30 kW output power assuming that it operates with natural gas. The developed model of the system is simulated in the environment of MATLAB/Simulink. Each part of the micro turbine generation system is represented by a mathematical model. On the basis of the developed model of the system, the minimum value of the supercapacitor was determined, which ensures the charging schedule of a selected electric vehicle. [ABSTRACT FROM AUTHOR]

A significant amount of the literature is focused on converters that supply the required voltage with low input-current ripple to electronic devices. A hybrid converter that combines boost and Cuk converters was developed recently. This hybrid converter achieved a relatively low input-current ripple based on earlier strategies. This paper proposes a new model that simulates a hybrid power converter system using a unified evolutionary algorithm (EA). As part of this paper, we present an improved framework for a hybrid power converter. Moreover, a unified EA is developed to incorporate differential evolution (DE) and genetic algorithm (GA) properties in order to analyze the proposed modified hybrid power converter. This research describes a modified hybrid power converter that optimizes the zero-ripple duty cycle (DZ) through the proposed algorithm for minimizing the input-current ripple. Based on our simulation results, comparing the proposed method with the baseline algorithm reveals that the proposed approach is significantly more efficient than the baseline algorithm and achieves the minimum input-current ripple in different gain values. In addition, we observe that the proposed algorithm performs better than the DE and GA algorithms in terms of obtaining low input-current ripple results. Therefore, the proposed hybrid algorithm is becoming more efficient with hybridization. [ABSTRACT FROM AUTHOR]

The growing use of power converters connected to the grid motivates their study in power electronics courses and the prototype development in the degree final project (DFP). However, the practical realization of using state-of-the-art components and conversion techniques is complex due to the numerous multidisciplinary aspects that students must consider in its design and development and the workload associated with the DFP. An example of this is that, unlike a conventional power factor correction (PFC) design, the individual dedication of students to complete the design and validation of modern bridgeless PFC stages exceeds the number of credits of the DFP. The reason for this is that it includes system modeling, becoming familiar with the devices used, discrete selection, circuit design, control development, and programming, to build the converter and verify the operation of the complete system. To reinforce the individual skills needed for the DFP and reduce this time, a novel strategy is proposed. It allows the student to focus their efforts on integrating the individual skills achieved in the degree at the appropriate competence level during the modeling and construction of the power converter while carrying out part of the tasks out of the lab, if necessary, as was the case during the pandemic restrictions. For this, the rapid prototyping technique is introduced to speed up the overall design and speed up the tuning of digital controllers. This manuscript presents a teaching experience in which students build digitally controlled power converters using Texas Instruments microcontroller boards and PLECS®. The example of a bridgeless totem-pole power factor corrector is shown. Although it began to develop and was motivated due to the restrictions during the COVID-19 pandemic, the experience has been verified and is maintained over time, successfully consolidating. [ABSTRACT FROM AUTHOR]

This paper presents a survey of the articles published in the period 2013–2021 related to the application of the teaching–learning-based optimization (TLBO), which reproduces the dynamics that occur in a classroom with the teacher and the student. This paper uses the algorithm to optimize some objective functions related to the design in the electronics field. A total of 62 papers were reviewed and some graphs were generated to summarize the most relevant of these articles. These have been classified into five categories based on the areas of electronic engineering, such as power electronics, control, electromagnetism, digital electronics, and analogue electronics. Electronic engineering has been becoming increasingly relevant in world technological development, for example, in electric vehicles or generating electricity from renewable energy sources to counteract the environmental impact that non-renewable sources generate. The TLBO algorithm has attracted the interest of a large number of researchers due to its efficiency, speed, and low initialization parameter requirements. This article is composed of two stages, the first is a summary of the information on electronics, in general, encompassing all its areas, and the second focuses on the algorithm applied to multilevel inverters; for each stage, graphs and tables are shown. [ABSTRACT FROM AUTHOR]

Friction stir welding requires an optimized process because the quality of the weld can vary depending on the dynamic characteristics of the welding tool. In addition, controlling the structural deflection of the base material according to the load of the welding tool is important. In this study, the structural deflection of thin base material according to the dynamic characteristics of the welding tool was confirmed using dynamic simulation. The generated deflection was controlled through the fixing clamp, and the results according to the rotation and progress speed of the welding tool were compared and analyzed through finite volume analysis. Thus, factors of the welding tools were obtained based on computational data without accompanying experimental data, and a process guide for efficient friction stir welding for thin base materials was presented. [ABSTRACT FROM AUTHOR]

This paper presents the study of air-core transformers for electric vehicles, developing them for medium-power (tens of kWs) converter applications specifically used at a high frequency. Air-core transformers have the advantage of lacking magnetic saturation and iron losses, making them suitable for high-frequency applications. We designed and manufactured a transformer for a determined frequency and inductance value. The design of this passive component aims to both keep the magnetic field inside the transformer and manage the thermal energy efficiently. The electrical, magnetic, and thermal properties are simulated and then verified by experiments with a specific test bench. The transformer reaches high performances for a higher frequency than usual for an equivalent power transfer in automotive applications. [ABSTRACT FROM AUTHOR]

To provide ancillary services in HVDC applications, modular multilevel converters (MMCs) with integration of energy storage systems are a promising solution as they take advantage of the modularity and the controllability of the stored energy. In these solutions, an energy storage system is connected to the DC capacitor of a submodule (SM) to make an energy storage submodule (ES-SM). An MMC with partial integration (MMC-PIES) is an MMC with each arm made of a mix of SMs and ES-SMs. In this paper, we propose a novel design methodology for these converters considering they are built based on existing prebuilt submodules, while design methodologies in the literature consider the SM and ES-SM characteristics to be degrees of freedom. Therefore, the proposed approach is closer to an industrial standpoint and computes the minimum number of ES-SMs to comply with requirements. We also include a new optimization method for the circulating currents needed to balance the energy in the SM and ES-SM capacitors. Design scenarios are presented. The results show that the value of the DC capacitance and the current limitation of the switches highly influence the design, restricting the possible operating points. In addition, half-bridge ES-SMs seem to be a more promising solution than full-bridge ES-SMs, reducing the number of ES-SMs. [ABSTRACT FROM AUTHOR]

Increasing wind generation insertion levels on electrical grids through power converters may cause instabilities in the AC grid due to the intermittent wind nature. Integrating a Battery Electric Energy Storage System (BESS) in wind generation can smooth the power injection at the Common Coupling Point (PCC), contributing to the power system voltage and frequency stability. In this article, it is proposed to analyze the operation of a lithium-ion battery technology based 1 MW/1.29 MWh BESS connected in parallel with wind generation with a capacity of 50.4 MW. The main characteristics investigated are power smoothing and power factor correction. Experimental results show that BESS contributes to smoothing the active power and correcting the power factor of wind generation, improving the quality of electrical energy at the PCC. [ABSTRACT FROM AUTHOR]

The design of a fully superconducting wind power generator is influenced by several factors. Among them, a low number of pole pairs is desirable to achieve low AC losses in the superconducting stator winding, which greatly influences the cooling system design and, consecutively, the efficiency of the entire wind power plant. However, it has been identified that a low number of pole pairs in a superconducting generator tends to greatly increase its output voltage, which in turn creates challenging conditions for the necessary power electronic converter. This study highlights the interdependencies between the design of a fully superconducting 10 MW wind power generator and the corresponding design of its power electronic converter. [ABSTRACT FROM AUTHOR]

Due to environmental concerns, governments around the world are taking measures to decarbonise railway transport by replacing diesel traction systems with cleaner alternatives. While the electrification of railway systems is spreading rapidly, it is unlikely that all routes will be electrified as the volume of passengers will not justify the high infrastructure costs. Therefore, it is expected that, for several lines, a combination of hydrogen and electric traction will be used, with the latter partly provided by fixed infrastructure and partly by batteries. Railway traction drives will then need to change to accommodate these new types of power supply. A detailed review of the available traction motors and drives is provided with this review, given application to the new hybrid-electric systems. In particular, permanent magnet synchronous motors with multiphase windings are evaluated in comparison with traditional three-phase machines. Additionally, low and medium-voltage multisource power converters have been reviewed, taking into account the introduction of wide band-gap semiconductor devices. [ABSTRACT FROM AUTHOR]

The increasing deployment of power converters has led to a significant reduction in the power system inertia and consequently resulted in frequency stability issues. To improve the robustness of the grid against frequency disturbances, it is becoming more expected in many countries that renewable energy generation, such as wind turbine power systems, should provide equivalent inertia support to the power system. This can be achieved through advanced control of power converters, in addition to adding extra energy storage devices, e.g., batteries. In wind turbine systems, although the ancillary service of inertia provision can be realized by coupling the rotor speed with the grid frequency, the rotor speed recovery process affects the inertia response if the controller is not properly designed or well-tuned. To address this issue, in this paper, we propose a multi-timescale control strategy for a doubly fed induction generator (DFIG) wind turbine system. Synthetic inertia control and speed recovery control are simultaneously incorporated into the controller of the rotor-side converter, whereas their dynamics are decoupled under different timescales to avoid control conflict. Extensive simulation results are provided, which validate the efficacy of the proposed inertia emulation scheme. [ABSTRACT FROM AUTHOR]

Power semiconductor devices in the power converters used for motor drives are susceptible to wear-out and failure, especially when operated in harsh environments. Therefore, detection of degradation of power devices is crucial for ensuring the reliable performance of power converters. In this paper, a deep learning approach for online classification of the health states of the snubber resistors in the Insulated Gate Bipolar Transistors (IGBTs) in a three-phase Brushless DC (BLDC) motor drive is proposed. The method can locate one out of the six IGBTs experiencing a snubber resistor degradation problem by measuring the voltage waveforms of the three shunt resistors using voltage sensors. The range of the degradation of the snubber resistors for successful classification is also investigated. The off-the-shelf deep Convolutional Neural Network (CNN) architecture ResNet50 is used for transfer learning to determine which snubber resistor has degraded. The dataset for evaluating the above classification scheme of IGBT degradation is obtained by measuring the shunt voltage waveforms with varying snubber resistance and reference current. Then, the three-phase voltage waveforms are converted into greyscale images and RGB spectrogram images, which are later fed into the deep CNN. Experiments are carried out on the greyscale image dataset and the spectrogram image dataset using four-fold cross-validation. The results show that the proposed scheme can classify seven classes (one class for normal condition and six classes for abnormal condition in one of the six IGBTs in a three-phase BLDC drive) with over 95% average accuracy within a specific range of snubber resistance. Using grayscale images and using spectrogram-based RGB images yields similar accuracy. [ABSTRACT FROM AUTHOR]

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary. [ABSTRACT FROM AUTHOR]

Feature Application: A novel strategy is proposed to address open-circuit fault diagnosis of grid side full-scale power converters of wind turbines. The power converter is a significant device in a wind power system. The wind turbine will be shut down and off grid immediately with the occurrence of the insulated gate bipolar transistor (IGBT) module open-circuit fault of the power converter, which will seriously impact the stability of grid and even threaten personal safety. However, in the existing diagnosis strategies for the power converter there are few single and double IGBT module open-circuit fault diagnosis methods producing negative results, including erroneous judgment, omissive judgment and low accuracy. In this paper, a novel method to diagnose the single and double IGBT modules open-circuit faults of the permanent magnet synchronous generator (PMSG) wind turbine grid-side converter (GSC) is proposed: Primarily, by collecting the three-phase current varying with a wind speed of 22 states, including a normal state and 21 failure states of PMSG wind turbine GSC as the original signal data. Afterward, the original signal data are decomposed by using variational mode decomposition (VMD) to obtain the mode coefficient series, which are analyzed by the proposed method base on fault trend feature for extracting the trend feature vectors. Finally, the trend feature vectors are utilized as the input of the deep belief network (DBN) for decision-making and obtaining the classification results. The simulation and experimental results show that the proposed method can diagnose the single and double IGBT modules open-circuit faults of GSC, and the accuracy is higher than the benchmark models. [ABSTRACT FROM AUTHOR]

In relation to power converter design, power density is increasing while the form factor is decreasing. This trend generally reduces the rate of the cooling process, which increases the mutual thermal coupling among the surrounding power components. Most of the traditional models usually ignore the mutual effects or just focus on the conduction coupling. To deal with these factors, the thermal modeling for a boost converter system has been built to compare the junction temperatures (Tj) and the increments under different working conditions in order to consider the conduction coupling. A multi-variable thermal resistances model is proposed in this paper to incorporate the convection thermal coupling into the mutual thermal effects. The coupling resistances, MOSFET to the diode ( R cp- MD ⇀ ), and the diode to MOSFET ( R cp- DM ⇀ ) have been calculated and the relationships between coupling resistances and their impact factors (separation distances and working currents) have been discussed. New case temperatures (Tc) obtained by calculation and additional measurements at other separation distances serve to verify the efficacy of the proposed model. This model enhances the current thermal models and provides an effective method to calculate the thermal coupling resistances which can be used to estimate the Tj. As the coupling resistances are distance dependent, the model also helps to optimize and fine-tune the placements of components in high-power density converters. [ABSTRACT FROM AUTHOR]

Featured Application: The proposed circuit model is able to foresee the overall current distortion of different lamp configurations. This feature is very useful in the optimal design of lighting systems when a key target is the mitigation of the current distortion due to the power converter inside the energy-saving lamps. Energy-saving lamps are equipped with converters enabling high energy efficiency at the cost of injecting very distorted currents on the mains. The problem is more complex in the emerging smart-lighting scenario where these lamps are also used to perform additional tasks. Harmonics mitigation at the lamp level is expensive; consequently, an optimal lighting system design aiming at reducing both costs and current distortion of the whole lighting system is necessary. A tool able to emulate the current drawn from the lamps is necessary for optimal design. Such a tool has also to consider the fluctuations of the voltage on the mains that usually occur throughout the day. In this perspective, a parametric PSpice circuit is proposed and the netlist is reported in this work. Moreover, the simple procedure to be adopted for computing the parameters is also described. The validation has confirmed the ability of the proposed circuit in emulating the current drawn from various CFLs and LED lamps under different supplying voltage. [ABSTRACT FROM AUTHOR]

In this paper, a complete computer aided procedure based on the power density concept and aimed at the automatic design of EMI filters for power electronic converters is presented. It is rule-based, and it uses suitable databases built-up by considering information on passive components available from commercial datasheets. The power density constraint is taken into consideration by imposing the minimization of the filter volume and/or weight; nevertheless, the system in which the automatically designed filter is included satisfies the electromagnetic compatibility standards limits. Experimental validations of the proposed procedure are presented for two real case studies, for which the performance and the size of the best filter design are compared with those related to a conventionally designed one. [ABSTRACT FROM AUTHOR]

By the application of well-known circuit analysis techniques, this paper develops an intuitive approach to model the steady state regime of the three DC/DC power converters' basic topologies (buck, boost and buck-boost). The developed approach can be considered new, realistic, accurate, general and practical. The approach is new because it is not present in the literature; realistic because it considers the main non-idealities of the different passive and active components that make up the converters; accurate because its theoretical results fit properly to those obtained in actual converters; general because it is valid for the three basic topologies; and practical because its applicability is easy and immediate from the data sheets of the converters' components (no measurements are needed). The developed model transforms a complex system with strong non-idealities in the form of distributed parameters, in a simple and intuitive scheme of concentrated parameters (just three), which accurately reflects the actual behavior of the three basic converters' topologies. The characteristic parameters of the model and its main relationships are determined analytically. The quality of the developed approach has been tested in the paper and can be considered excellent. [ABSTRACT FROM AUTHOR]

To efficiently supply wide-range DC voltage from a pulse-width modulation (PWM) rectifier, this paper presents a single-phase, full-wave, diode-bridge, single-ended primary-inductor converter-type (SEPIC-type) power-factor-correction (PFC) rectifier in continuous conduction mode with a sliding surface-regulated current-mode PWM controller. According to the switched-mode operation of the rectifier, a fourth-order switch model of the SEPIC is derived. From the fourth-order model, a simplified state-averaged model which approximately describes the dynamic behaviors of both the output voltage and inductor current is proposed. Then, from the simplified state-averaged model, the sliding surface-regulated current-mode PWM controller for the SEPIC-type PFC rectifier is proposed. The sliding surface-regulated current-mode PWM controller comprises a sliding-mode voltage controller in outer loop for robust control of the output DC-voltage and a sliding-mode current controller in inner loop for phase-synchronized control of the inductor current. For experimental studies, implementation of the proposed control algorithm in a DSP controller and a laboratory prototype of the SEPIC-type rectifier with the DSP-based PWM controller were carried out. Experimental results from the DSP controller-applied SEPIC-type rectifier are illustrated to confirm the validity of the proposed controller for practical applications. [ABSTRACT FROM AUTHOR]

Although Permanent Magnet Synchronous Generator (PMSG) wind turbines (WTs) mitigate gearbox impacts, they requires high reliability of generators and converters. Statistical analysis shows that the failure rate of direct-drive PMSG wind turbines' generators and inverters are high. Intelligent fault diagnosis algorithms to detect inverters faults is a premise for the condition monitoring system aimed at improving wind turbines' reliability and availability. The influences of random wind speed and diversified control strategies lead to challenges for developing intelligent fault diagnosis algorithms for converters. This paper studies open-circuit fault features of wind turbine converters in variable wind speed situations through systematic simulation and experiment. A new fault diagnosis algorithm named Wind Speed Based Normalized Current Trajectory is proposed and used to accurately detect and locate faulted IGBT in the circuit arms. It is compared to direct current monitoring and current vector trajectory pattern approaches. The results show that the proposed method has advantages in the accuracy of fault diagnosis and has superior anti-noise capability in variable wind speed situations. The impact of the control strategy is also identified. Experimental results demonstrate its applicability on practical WT condition monitoring system which is used to improve wind turbine reliability and reduce their maintenance cost. [ABSTRACT FROM AUTHOR]

This paper compares the differences in economic feasibility and dynamic characteristics between underground (U/G) cable and overhead (O/H) line for low-voltage direct current (LVDC) distribution. Numerous low loaded long-distance distribution networks served by medium-voltage alternative current (MVAC) distribution lines exist in the Korean distribution network. This is an unavoidable choice to compensate voltage drop, therefore, excessive cost is expended for the amount of electrical power load. The Korean Electric Power Corporation (KEPCO) is consequently seeking a solution to replace the MVAC distribution line with a LVDC distribution line, reducing costs and providing better quality direct current (DC) electricity. A LVDC distribution network can be installed with U/G cables or O/H lines. In this paper, a realistic MVAC distribution network in a mountainous area was selected as the target model to replace with LVDC. A 30 year net present value (NPV) analysis of the economic feasibility was conducted to compare the cost of the two types of distribution line. A simulation study compared the results of the DC line fault with the power system computer aided design/electro-magnetic transient direct current (PSCAD/EMTDC). The economic feasibility evaluation and simulation study results will be used to select the applicable type of LVDC distribution network. [ABSTRACT FROM AUTHOR]

A laboratory-scale passive hybrid power system for transportation applications is constructed and tested in this study. The hybrid power system consists of a fuel cell stack connected with a diode, a lithium-ion battery pack connected with a DC/DC power converter and another diode. The power converter is employed to regulate the output voltage of the battery pack. The dynamic responses of current and voltage of the stack to the start-up and acceleration of the load are experimentally investigated at two different selected output voltages of the DC/DC converter in the battery line. The power sharing of each power source and efficiency are also analyzed and discussed. Experimental results show that the battery can compensate for the shortage of supplied power for the load demand during the start-up and acceleration. The lowest operating voltage of the fuel cell stack is limited by the regulated output voltage of the DC/DC converter. The major power loss in the hybrid power system is attributed to the diodes. The power train efficiency can be improved by lowering the ratio of forward voltage drop of the diode to the operating voltage of the fuel cell stack. [ABSTRACT FROM AUTHOR]

Analysis of power converter performance has tended to be engineering-oriented, focusing mainly on voltage stability, output power and efficiency improvement. However, there has been little discussion about the weight relations between these factors. In view of the previous inadequacy, this study employs regression, rough set and GM(1,N) to analyze the relations among the factors that affect the converter, with a symmetrical half-bridge power converter serving as an example. The four related affecting factors, including the current conversion ratio, voltage conversion ratio, power conversion ratio and output efficiency, are firstly analyzed and calculated. The respective relative relations between output efficiency and the other three factors are obtained. This research can be referred to by engineers in their design of symmetrical half-bridge power converters. [ABSTRACT FROM AUTHOR]

Investigating the performance of power electronics devices and thus power inverters at cryogenic temperatures for electric aircraft systems are of great interest. Accordingly, the purpose of this study is to examine the inverter circuit technologies used in cryogenically-cooled electric aircraft applications from three perspectives: inverter topologies, power capabilities, and electromagnetic interference (EMI) that may occur. At a cryogenic temperature, the characteristics of five power semiconductor switches with different technologies (Si MOS, SiC MOS, and GaN HEMT) used in cryogenically-cooled electric aircraft inverters were tested and the results were presented. Furthermore, the low-temperature performance of three types of capacitors commonly used in power electronics inverters was investigated. The research findings provide crucial considerations for the research and development of power inverters cooled by sub-cooled liquid nitrogen for modern electric aircraft. [ABSTRACT FROM AUTHOR]