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The LLC resonant converter, which is extensively utilized across various industrial fields, significantly depends on its parameters for performance optimization. This paper establishes a time-domain analytical model for the LLC resonant converter under Pulse Frequency Modulation (PFM) and proposes a multi-objective parameter optimization design method with stepwise constraints. The proposed method limits the resonant capacitor voltage while ensuring that the converter meets the voltage gain requirement and realizes Zero-Voltage Switching (ZVS). The converter's performance is then optimized with the objective of minimizing the switching frequency range, the resonant inductor current, and the RMS value of the switching current on the secondary side. Compared with the existing methods, the proposed method has the advantages of comprehensive consideration and wide application scenarios. Finally, a 1200 W experimental prototype was fabricated, with experimental results verifying the feasibility of the proposed optimization design method and demonstrating that the prototype's maximum efficiency reaches 96.54%. [ABSTRACT FROM AUTHOR]

Mathematical models are the base for unified methods of calculating and designing radio-electronic devices. The developed limiting continuous mathematical model of a DC/DC converter built using the SEPIC topology allows us to estimate the range of changes in currents flowing through the windings of the inductors and voltages on the capacitor plates, as well as determine their maximum and minimum values for various converter parameters, such as the power switching frequency key, fill factor, element values, etc. The research results show that the phase coordinates of the mathematical model tend to the real values of the currents and voltages of the converter when the switching frequency of the power switch is more than 200 kHz. A correspondence was established between the calculated values of the ripple ranges and the results obtained during modeling (with changes in the duty cycle and switching frequency of the power switch). [ABSTRACT FROM AUTHOR]

This paper investigates the dc-bus voltage balancing for 3-level DC/DC converters. First, the system control diagram is introduced. Then, based on duty cycle and operating modes, four different cases are illustrated. The output voltages under four cases are detailed, and the dc-bus voltage balancing actions for different cases are summarized. The dc-bus voltage balancing situation becomes worse when the system is in the condition of D > 0.5 and DCM. Therefore, three methods are proposed to solve the issue raised. The first method is to limit D≤0.5. The second method applies an opposite control when D > 0.5 and DCM. The third solution adopts an intelligent control.

PV arc-faults can cause fires, damage property, and endanger people's lives. This paper proposes a method for detecting DC arcs using artificial intelligence (AI). The four steps for arc detection are thoroughly described. After removing the low-frequency range (41 kHz) and high-frequency range (>102.5 kHz) components, the middle frequency range is left for arc analysis. For AI analysis, eight inputs are used. The time sequence for the tasks is also explained, where the parallel task configuration is adopted to save the time. Furthermore, AI model training for arc detection is described, including both offline and online training. In addition, three different types of arc detection system architectures are depicted. There are three layers in the architectures: the PV-end layer, the inverter-level layer, and the cloud layer. Depending on the architecture, the algorithm is located in different layers. Furthermore, the hardware of the arc detection system is explained, as is the self-testing circuit. Finally, an experimental platform is built, and experimental results are presented to validate the proposed method.

DC/DC converters are widely used as power supplies in various power supply systems. Their faults can lead to improper system operation. Building intelligent fault diagnosis models for 'highly reliable and long-life' DC/DC converters is challenging due to the high data acquisition costs and insufficient fault data. In this paper, the digital twin (DT) technique is utilized to provide extensive and reliable data to address the issue of insufficient data for diagnosing DC/DC converter faults. However, establishing multidisciplinary, multi-physical quantity, multi-scale, and multi-probability virtual models (VMs) can be challenging. Thus, a cloud model-based interpretable transfer model is designed to overcome the limitations of VMs in fully deducing the full-state output properties. The proposed method effectively diagnoses DC/DC converters based on DT technology by providing a more comprehensive and uniformly distributed source domain data to suit the samples in the target domain. Comparison with other algorithms shows the effectiveness of the proposed method. It has the potential to provide accurate and real-time diagnosis for DC/DC converter faults and enable timely maintenance strategies for power monitoring in equipment, such as submarine observation networks and space power supply systems. [ABSTRACT FROM AUTHOR]

Catalyzed by the increasing interest in bi-directional electric vehicles, this paper delves into their significance and the challenges they encounter. Bi-directional electric vehicles not only serve as transportation but also function as essential electricity resources. Central to this energy revolution are On-Board Chargers (OBCs), which are pivotal in converting alternating (AC) energy into direct (DC) energy and vice versa. In this context, we explore the various circuit architectures of OBCs employed in bi-directional electric vehicles. We delve into the intricacies of rectifiers, switching converters, and the application of advanced control and filtering technologies. Our analysis extends to the implications of these circuit architectures on aspects such as voltage regulation capability, energy efficiency, and thermal management. Furthermore, we address the broader significance of these developments in the integration of bidirectional systems, which are driving advances in circuit architectures to better harness the energy flexibility of electric vehicles. We emphasize the critical role of bi-directional electric vehicles in the transition toward a smart and sustainable energy grid. To enhance accessibility for a diverse readership, we will provide concise definitions or explanations for technical terms used throughout the paper, ensuring that our work is approachable even for those who may not be experts in the field. [ABSTRACT FROM AUTHOR]

The paper presents an innovative approach to control the voltage of an LCL-T type converter at the output side against variation at input and load ports, utilizing a fixed-frequency phase-shift control scheme. The examination of the converter is performed employing a Fourier series method that takes into account the effect of n-harmonics. To assure high-frequency switches with a zero-voltage switching (ZVS) technique, the lagging pf mode is utilized. PSIM simulations were used to investigate the performance of a 300 W converter. With the minimal input voltage, all switches turn on with ZVS for all loading conditions, whereas the ZVS strategy loses by two switches when the voltage at the input is highest. The power loss calculations of each component are performed and presented in a pie chart. The findings of the experiments are presented and verified with theoretical and simulation results. It is demonstrated that for both input voltage and load fluctuations, a minor adjustment in pulse width is sufficient to keep the output voltage constant. [ABSTRACT FROM AUTHOR]

One of the maximum popular renewable electricity assets is photovoltaics. Grid-connected photovoltaic structures are designed to generate as a lot strength as possible. Photovoltaic systems have nonlinear traits imposed with the aid of environmental factors consisting of radiation and temperature, making it hard to operate at the most power factor. It may additionally be tough to extract the maximum amount of electricity due to the formation of nearby maxima because of other factors which include shading or degradation. There are several MPPT algorithms and approaches that may be used for this. Publications with comparative analyses have also been released. However, in most of these works, comparisons are based on simulations or literature review. From the simplest to the most complex MPPT methods, empirical validation remains important. The two simplest and most widely used MPPT techniques are the perturbation, open-loop, and incremental conductance algorithms. The three most challenging ones are sliding mode control, backstepping controller, and particle swarm optimization. Therefore, five MPPT algorithms are empirically studied in this paper. Under test settings, Matlab/Simulink was used to conduct experimental experiments. The findings demonstrate that under ordinary operating circumstances, the backstepping algorithm is the only one capable of finding the global MPP under the influence of local shadowing. [ABSTRACT FROM AUTHOR]

The LLC resonant converter, which is extensively utilized across various industrial fields, significantly depends on its parameters for performance optimization. This paper establishes a time-domain analytical model for the LLC resonant converter under Pulse Frequency Modulation (PFM) and proposes a multi-objective parameter optimization design method with stepwise constraints. The proposed method limits the resonant capacitor voltage while ensuring that the converter meets the voltage gain requirement and realizes Zero-Voltage Switching (ZVS). The converter’s performance is then optimized with the objective of minimizing the switching frequency range, the resonant inductor current, and the RMS value of the switching current on the secondary side. Compared with the existing methods, the proposed method has the advantages of comprehensive consideration and wide application scenarios. Finally, a 1200 W experimental prototype was fabricated, with experimental results verifying the feasibility of the proposed optimization design method and demonstrating that the prototype’s maximum efficiency reaches 96.54%.

The wide-scale adoption and accelerated growth of electric vehicle (EV) use and increasing demand for faster charging necessitate the research and development of power electronic converters to achieve high-power, compact, and reliable EV charging solutions. Although the fast charging concept is often associated with off-board DC chargers, the importance of on-board AC fast charging is undeniable with the increasing battery capacities. This article comprehensively reviews gallium nitride (GaN) semiconductor-based bidirectional on-board charger (OBC) topologies used in both 400 V and 800 V EV applications. Moreover, comparative evaluations of GaN-based bi-directional OBC topologies regarding power conversion losses (conduction loss and soft switching capabilities), power density, implementation considerations, power quality, electromagnetic interference, and reliability aspects have been presented. The status of commercially available GaN power modules, advancements in GaN technology, applicable industry standards, and application requirements for OBCs have been also included in this study. Finally, in light of forthcoming advancements in GaN power transistor technology, this study highlights potential areas of research related to the reviewed topologies. Such research can aid researchers and designers in improving the performance and user experience of electric vehicles, ultimately supporting the widespread adoption of EVs. [ABSTRACT FROM AUTHOR]

The inclusion of solar systems in rural microgrids is becoming increasingly important to supply energy for irrigation, electric motors, lighting and other. This paper presents the implementation of an exact linearization technique for the modeling and control of a DC/DC converter for use in a microgrid based on a photovoltaic (PV) generation system where non-linear converters are used. The basic advantage of this technique is in linearizing the converter model, thus allowing different operating points to be considered under different conditions. This paper presents a general description of the implemented microgrid topology. The exact linearization theory adapted for power converters is applied to both a Single-Ended Primary-Inductor converter (SEPIC) to extract energy from PV modules and to a Boost converter to increase the voltage. Experimental results are also presented to validate the effectiveness of the proposed control.

Two low voltage parallel full-bridges are proposed for the power supply of a two-axis electromagnetic micro-actuator. GaN FETs are chosen for these converters to achieve high efficiency while switching at high frequencies. The control strategy implements the phase shift between two branches of each full-bridge and the interleaved phase between two full-bridges, which reduces the load current ripple and increase the frequency of input and output current ripples. These properties help us miniaturize filtering coils and decoupling capacitors associated to the converters. The test bench that highly integrates the micro-actuator and converters was fabricated. Simulation and experimental results are compared for analysing and validating the integration and the proposed control strategy.

The paper presents an innovative approach to control the voltage of an LCL-T type converter at the output side against variation at input and load ports, utilizing a fixed-frequency phase-shift control scheme. The examination of the converter is performed employing a Fourier series method that takes into account the effect of n-harmonics. To assure high-frequency switches with a zero-voltage switching (ZVS) technique, the lagging pf mode is utilized. PSIM simulations were used to investigate the performance of a 300 W converter. With the minimal input voltage, all switches turn on with ZVS for all loading conditions, whereas the ZVS strategy loses by two switches when the voltage at the input is highest. The power loss calculations of each component are performed and presented in a pie chart. The findings of the experiments are presented and verified with theoretical and simulation results. It is demonstrated that for both input voltage and load fluctuations, a minor adjustment in pulse width is sufficient to keep the output voltage constant.

A multi-level boost topology based on a flying capacitor is compared in this work with the hybrid, multi-level, partial power processing topology already presented in the literature for use as a highly efficient and compact dc/dc stage in 1500-V, two-stage, grid-connected PV systems. Different variations of the resonant stage of the hybrid topology are analyzed and compared in terms of losses, volume and complexity. Full multivariable optimization is conducted for the multi-level boost topology with different number of levels and for all the analyzed variations of the resonant stage of the hybrid topology. Appropriately rated new classes of 650-V and 900-V WBG devices are included in the optimization algorithm. It is concluded that due to the dominant conduction losses and gap in the voltage rating of the commercially available WBG devices between 650V and 200V, increase of the number of levels over 4 leads to the deteriorated loss and volume performances. All the analysis related to the resonant stage of the hybrid topology is confirmed by detailed and comprehensive measurements of two prototypes of 4kW of nominal and 7kW of maximal power. Additionally, all the loss models applied in the optimization algorithms presented in this paper are confirmed by detailed measurements, thermal calibration and finite element thermal simulations of the wide bandgap devices and inductor designs employed in this work. [ABSTRACT FROM AUTHOR]

The excessive use of fossil fuels has caused great concern due to modern environmental problems, particularly air pollution. The above situation demands that different areas of research aim at a sustainable movement to reduce CO 2 emissions caused by non-renewable organic fuels. A solution to this problem is the use of Electric Vehicles (EV) for mass transportation of people. However, these systems require high-power DC/DC converters capable of handling high current levels and should feature high efficiencies to charge their batteries. For this application, a single-stage converter is not viable for these applications due to the high current stress in a switch, the low power density, and its low efficiency due to higher switching losses. One solution to this problem is Multiphase Converters, which offer high efficiency, high power density, and low current ripple on the battery side. However, these characteristics are affected by the current imbalance in the phases. This paper is focused on the study of the effects of the current imbalance in a Multiphase Buck Converter, used as an intermediate cover between a power supply and the battery of an EV. Analyzing the efficiency and thermal stress parameters in different scenarios of current balance and current imbalance in each phase. [ABSTRACT FROM AUTHOR]

Non-inductive (throttle-free) DC/DC converters are used in low-power and highly integrated electronic systems. A circuit analysis of the basic topologies of non-inductive DC/DC charge-pumped converters which perform typical DC-voltage conversions, i.e., lowering, raising and inverting, was carried out. The galvanic isolation between the input and output circuits of the converter was achieved even in the integrated version due to forming a time delay of the switches (Dead Time, DT), commuting a “flying” capacitor, which is transferring the charge to the storage capacitor and the load. A circuit of the DT driver was developed and its parameters, at which the through-current flow in the switch is prevented and the conditions of galvanic isolation of the input and output circuits are satisfied, were studied. The simulation was built with a popular Electronics Workbench software, widely used in training of specialists in radio electronics at higher educational institutions. The results of the study of the basic power characteristics of DC/DC conversion, such as output current and voltage, voltage transfer coefficient, efficiency, output equivalent resistance, were presented. The efficiency of conversion was estimated by varying the capacities of the “flying” and storage capacitors, the resistance of the switches in the closed state, and the frequency of switching. It is proved that the charge pumping method is simple and effective at low load currents (mA units), when both the voltage transfer coefficient from input to output and efficiency are high, and are approaching to “one”. However, with the increase of the load current, the voltage transfer coefficient and efficiency decrease, the output voltage ripples increase.

With the development of technology, people′s life rhythm is accelerating, thereby increasing the frequency of using mobile phones and making the previous wireless charging solutions unable to meet people′s needs. Therefore, fast wireless charging solutions with high efficiency and low interference are desirable in people′s lives. DC/DC voltage regulation can achieve digitally controllable voltage, and is widely used because of its high efficiency and good stability. Based on the principle of DC/DC voltage regulation, this paper designs two fixed frequency voltage regulation schemes for fast wireless charging, theoretically derives parameter settings in the circuits, and finally implements them according to the designed schemes. Performance tests and model experiments validate the correctness and effectiveness of the theoretical derivations and scheme designs, and indicate the proposed schemes have important application value.

An IGBT/MOSFET driver circuit works at a low voltage, between 5-15 V of its gate voltage to drive power converter switching devices that work at higher voltages. If there is no isolation between the driver and power converter circuits, any damage that may occur to the power converter circuit at high voltage will damage the driver circuit as well. This paper presents a design of an isolated IGBT/MOSFET driver circuit for an interleaved DC/DC boost converter using a TL494 IC to generate the required pulses for the converter’s circuit. Isolation is done using optocouplers. An IC IR2117 driver is also used to produce smooth rise and fall times for the pulses for each IGBT. The designed driver circuit is modelled using a co-simulation employing Multisim and LabVIEW software and then implemented experimentally with the help of a NI PCI-DAQ 6259. A P-I controller is implemented to regulate the output voltage of the boost converter, as well at the desired set point.

In this article, a 10 MHz dc/dc converter based on three-dimensional air core transformer with zero-phase difference synchronous driving signals is designed. By using the characteristics of no leakage inductance in the inner winding of the nested toroidal air core transformer, the phase difference between the output voltage of the inverter and the input voltage of the rectifier can be regarded as zero, so that the rectifier and the inverter can use the same driving signal, which simplifies the control of the synchronous rectifier switches, and realizes the reliable and efficient synchronous rectification control at 10 MHz. The prototypes with primary and secondary compensation are proposed and the experimental results verify the feasibility of the proposed control method and numerical design method. [ABSTRACT FROM AUTHOR]

The excessive use of fossil fuels has caused great concern due to modern environmental problems, particularly air pollution. The above situation demands that different areas of research aim at a sustainable movement to reduce CO2 emissions caused by non-renewable organic fuels. A solution to this problem is the use of Electric Vehicles (EV) for mass transportation of people. However, these systems require high-power DC/DC converters capable of handling high current levels and should feature high efficiencies to charge their batteries. For this application, a single-stage converter is not viable for these applications due to the high current stress in a switch, the low power density, and its low efficiency due to higher switching losses. One solution to this problem is Multiphase Converters, which offer high efficiency, high power density, and low current ripple on the battery side. However, these characteristics are affected by the current imbalance in the phases. This paper is focused on the study of the effects of the current imbalance in a Multiphase Buck Converter, used as an intermediate cover between a power supply and the battery of an EV. Analyzing the efficiency and thermal stress parameters in different scenarios of current balance and current imbalance in each phase.

This article investigated two cases of impulse transformer location selection in the DC-DC type two-step resonant converter, which fully segregates processes of taking and transferring energy between the input and its load. The electromagnetic processes during energy taking/transferring were studied, including active and static losses in the converter elements. Based on the suggested analytical-numerical method, the criteria for selecting the impulse transformer optimal transformation ratio, from the system efficiency point of view, was derived. The proposed optimization technique can be applied to a wide variety of input and output parameters. [ABSTRACT FROM AUTHOR]

High-gain DC/DC converters with high efficiency are needed in dc microgrid owed to the low voltage of power sources, e.g., photovoltaic-cell and fuel-cell. This paper proposed a new high-gain double-duty-triple-mode (DDTM) converter for dc-microgrid applications. The proposed DDTM converter operates in three modes to achieve higher voltage gain without utilizing transformer, coupled inductor, voltage multiplier, and multiple voltage lifting techniques, e.g., triple, quadruple voltage lift. The modes of operation of the converter are controlled through three switches with two distinct duty ratios (double duty) to achieve wide range duty ratio. The operating principle, voltage gain analysis, and efficiency analysis of the proposed converter are discussed in detail and to show its benefits comparison is provided with the existing high-gain converters. The boundary operating condition for continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is presented. The prototype of the proposed converters with 500-W power is implemented in the laboratory and experimentally investigated, which validate the performance and feasibility of the proposed converter. Due to double duty control, the proposed converter can be controlled in different ways and the thorough discussion on controlling of the converter is provided as a future scope.

An IGBT/MOSFET driver circuit works at a low voltage, between 5-15 V of its gate voltage to drive power converter switching devices that work at higher voltages. If there is no isolation between the driver and power converter circuits, any damage that may occur to the power converter circuit at high voltage will damage the driver circuit as well. This paper presents a design of an isolated IGBT/MOSFET driver circuit for an interleaved DC/DC boost converter using a TL494 IC to generate the required pulses for the converter's circuit. Isolation is done using optocouplers. An IC IR2117 driver is also used to produce smooth rise and fall times for the pulses for each IGBT. The designed driver circuit is modelled using a co-simulation employing Multisim and LabVIEW software and then implemented experimentally with the help of a NI PCI-DAQ 6259. A P-I controller is implemented to regulate the output voltage of the boost converter, as well at the desired set point. [ABSTRACT FROM AUTHOR]

The high-current delivered by a dedicated power supply is the condicio sine qua non to obtain the strong magnetic field produced by superconducting magnets. The end goal of such power supply is to control the current, very precisely, across this distinctive kind of load. To this extent, the topology and a specific mode of operation that fit the requirements is analyzed and presented in this article. To obtain a contemporary power supply design, a design optimization of the overall system with respect to efficiency and volume is carried out. Considering the modularity specification, the system is split into elementary building blocks and one optimally designed unit is practically implemented and verified against predictions from the design tool. In sum, this article provides the comprehensive design process for a modern 2-quadrant high-current low-voltage dc/dc power supply. [ABSTRACT FROM AUTHOR]

A major challenge in the implementation of flying capacitor multilevel (FCML) converters and hybrid switched-capacitor (SC) converters is providing gate drive power to the large number of floating switches. A common solution uses isolated dc/dc converters, which are bulky, expensive, and energy inefficient. To design more compact and efficient gate drive power supply circuits, five methods are presented and compared in this article: bootstrap at deadtime, cascaded bootstrap with low-dropout (LDO) regulator, double charge pump, gate-driven charge pump, and synchronous bootstrap. By leveraging the inherent properties of multilevel converters, these methods can overcome the limitation of conventional bootstrap method (diode forward voltage drop) and make it possible to transfer ground-referenced power to all of the floating switches for any FCML or hybrid SC converters. Compared with the typical isolated dc/dc solution, these methods have simple structure and operating principle and can be implemented with a small number of diodes, capacitors, and LDOs. Experimental results show that an example power supply circuit can cut the size of the power stage of a state of the art seven-level FCML converter by half at 1/6 of the cost. [ABSTRACT FROM AUTHOR]

Thermoelectric generators (TEGs) are devices that convert heat into electricity. This paper is about the design of a Maximum Power Point Tracking (MPPT) technique for a TEG module. The module is built using 204 TEGs connected in series. It is connected to the load through a DC/DC boost converter. The MPPT technique used in this work is the Interval Type 2 Fuzzy Logic Controller (IT2FLC). To verify its performance, the IT2FLC is compared with a traditional Perturb and Observe (P&O) MPPT algorithm in the case of power and voltage response at steady state, load switching, and through various ranges of temperature differences (ΔT). The TEG module is modeled and the whole system is simulated successfully using MATLAB SIMULINK R2017a.

Improving the power density of a power converter has many benefits for systems integration. Aspects such as thermal management, weight, conformation to mounting locations, and the footprint of the converter all become critical factors as systems continue to scale down in size. The flying capacitor multilevel converter topology is of interest because it has characteristics which contribute to high power density. This paper presents a quasi-square-wave zero-voltage switching (ZVS) multilevel dc–dc converter. ZVS greatly reduces switching losses and enables high-frequency operation of the converter. A hardware prototype is implemented, built on a flexible polyimide substrate circuit board. Experimental results show a peak system efficiency above 98.1%, an effective switching frequency of up to 3 MHz, and a power output of 250 W. [ABSTRACT FROM AUTHOR]

In this work, an identification technique of a simple, measurements-based SPICE (Simulation Program with Integrated Circuit Emphasis) model is presented for small low-cost Peltier cells used in thermoelectric generator (TEG) mode for low-temperature differences. The collection of electric energy from thermal sources is an alternative solution of great interests to the problem of energy supply for low-power portable devices. However, materials with thermoelectric characteristics specifically designed for this purpose are generally expensive and therefore often not usable for low cost and low power applications. For these reasons, in this paper, we studied the possibility of exploiting small Peltier cells in TEG mode and a method to maximize the efficiency of these objects in energy conversion and storage since they are economical, easy to use, and available with different characteristics on the market. The identification of an accurate model is a key aspect for the design of the DC/DC converter, in order to guarantee maximum efficiency. For this purpose, the SPICE model has been validated and used in a design example of a DC/DC converter with maximum power point tracking (MPPT) algorithm with fractional open-circuit voltage. The results showed that it is possible to obtain a maximum power of 309 µW with a Peltier cell 2 × 2 cm at a ΔT of 16 °C and the designed SPICE DC/DC converter performance proved the improvement and optimization value given by the TEG model identification. [ABSTRACT FROM AUTHOR]

Fuel cell power conditioners often require high step-up voltage gains to accommodate low input fuel cell voltages into high voltage busses. Traditional non-isolated DC-DC boost converters are unable to offer such as gains because of several parasitic elements and non-ideal behaviour of power semiconductors and driving circuits. Moreover, paralleled converters are also desirable to simplify power-up scaling and to reduce input/output current ripples. In this context, a very versatile non-isolated, high step-up voltage gain, interleaved boost converter is presented in this work. Steady-state analysis, simulation and evaluation of different converter structures are discussed in detail. Finally, a 500-W experimental prototype for Nexa Ballard 1.2 kW fuel cell specifications has been implemented and tested to verify the performance. • An interleaved DC-DC converter for medium and large power fuel cell power condition is presented. • Non-isolated and high DC voltage gain. • Circuit design, simulation and experimental validation with a 500-W, 24 V/100 V prototype. [ABSTRACT FROM AUTHOR]

Розглянуто варіанти розміщення імпульсного трансформатора в двоконтурному резонансному перетворювачі DC/DC типу з дозованим відбором і передачею енергії. Досліджено електромагнітні процеси вхідного і вихідного контурів з врахуванням втрат енергії в дроселях, діодах та транзисторах конвертора. На основі використання аналітично-числового методу обґрунтовано вибір коефіцієнту передачі трансформатора, що забезпечує максимальний ККД. Викладено методику оптимізації, придатну для застосування у разі варіації вхідних та вихідних параметрів перетворювача в широкому діапазоні можливих значень. Бібл. 3, рис. 7.

Many applications (electric vehicles, renewable energies, low-voltage DC grids) require simple, high-power density and low-current ripple-boost converters. Traditional step-up converters are limited when large transformation ratios are involved. In this work is proposed a step-up converter that brings together the characteristics of high gain, low ripple, and high-power density. From the converter proposal, a mathematical analysis of its operation is first performed, including its static transfer function, stress of components, and voltage and current ripples. Furthermore, it provides a design example for an application of Vin = 48 V to Vo = 270 V and 500 W. For its implementation, two different wide bandgap (WBG) semiconductor models have been used, hybrid GaN cascodes and SiC MOSFETs. Finally, the experimental results of the produced prototypes are shown, and the results are discussed.

Günümüz teknolojilerindeki hızlı gelişmeler, endüstriyel veya bireysel tüketicilerin mobil cihazlara olan ilgisini arttırmakta ve buna bağlı olarak Doğru Akım (DA) kullanımı da yaygınlaşmaktadır. DA kullanımına olan talebin büyümesi temel yarı iletken güç dönüştürücülerinden biri olan DA-DA dönüştürücülerin önemini de arttırmaktadır. Bu çalışmada yüksek frekanslı (280kHz) darbe genişlik modülasyon kontrollü (PWM) DA-DA senkron yükselten dönüştürücü tasarımı ve uygulaması gerçekleştirilmektedir. Tasarım ve uygulama aşamasında yüksek frekans ile çalışmanın meydana getirmiş olduğu problemler, kontrol katı ve güç katı olmak üzere ayrı ayrı değerlendirilerek, iyileştirme yöntemleri yarı iletken elemanlar ve baskı devre yapısı üzerinde uygulanarak deneysel olarak gözlemlenmiştir.

This study proposes a novel hybrid energy storage system (HESS) composed of a battery pack and a superconducting magnetic energy storage (SMES) for electric vehicle. Typically, the SMES has a higher power density and lower energy density than other energy storage devices, while battery has higher energy density. Thus, the overall HESS performance can be increased in power and energy density by combining SMES and batteries. The proposed HESS is designed based on bidirectional Z‐source inverter (ZSI). Compared to other SMES/battery‐based HESS topologies that are two stage designs (including DC/DC and AC/DC converters), in this topology, SMES and battery can be incorporated into the Z‐source network which results in lower cost and improved HESS performance. Furthermore, the battery converter has been eliminated due to the buck/boost feature of the ZSI. The fuzzy control method and filters are used to distribute power between the SMES and battery. This study also describes the proposed HESS performance principles and its operation in different modes. [ABSTRACT FROM AUTHOR]

In this work, an identification technique of a simple, measurements-based SPICE (Simulation Program with Integrated Circuit Emphasis) model is presented for small low-cost Peltier cells used in thermoelectric generator (TEG) mode for low-temperature differences. The collection of electric energy from thermal sources is an alternative solution of great interests to the problem of energy supply for low-power portable devices. However, materials with thermoelectric characteristics specifically designed for this purpose are generally expensive and therefore often not usable for low cost and low power applications. For these reasons, in this paper, we studied the possibility of exploiting small Peltier cells in TEG mode and a method to maximize the efficiency of these objects in energy conversion and storage since they are economical, easy to use, and available with different characteristics on the market. The identification of an accurate model is a key aspect for the design of the DC/DC converter, in order to guarantee maximum efficiency. For this purpose, the SPICE model has been validated and used in a design example of a DC/DC converter with maximum power point tracking (MPPT) algorithm with fractional open-circuit voltage. The results showed that it is possible to obtain a maximum power of 309 µW with a Peltier cell 2 × 2 cm at a ΔT of 16 °C and the designed SPICE DC/DC converter performance proved the improvement and optimization value given by the TEG model identification.

A bidirectional (Bi) DC/DC converter is one of the key components in a hybrid energy storage system for electric vehicles and plug-in electric vehicles. Based on the detailed analysis of the losses in the converter, this paper firstly develops a model to theoretically calculate the efficiency of the converter. Then, the influences of temperature, switching frequency, duty cycle and material of switching device on the converter’s efficiency are experimentally investigated. The analysis of the experimental results has shown that (1) The efficiency at the switching frequency of 15 kHz is about 2% higher than that of 25 kHz. (2) The efficiency at 25 °C is similar to that at 85 °C for the MOSFET SiC while the efficiency at 25 °C is 2% higher than that at 85 °C for the IGBT Si for both buck and boost modes. (3) In buck mode, when the duty cycles are decreasing from 66.7%, 50% to 33.33%, the peak efficiencies are also decreasing from 97.6%, 94.5% to 90.3%, respectively. In boost mode, when the duty cycle is increasing from 33.33%, 50% to 75%, the peak efficiency is decreasing from 96.9%, 96.5% to 92.4%, respectively. (4) The developed model can calculate the converter’s efficiency accurately [ABSTRACT FROM AUTHOR]

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With high penetration of renewable energies, power electronic transformers (PETs) will be one of the most important infrastructures in the future power delivery and management system. In this study, an isolated bidirectional modular multilevel DC/DC converter is proposed for PET applications. A modular multilevel structure is adopted as switching valves to sustain medium voltages to achieve modular design and high reliability. Only one high-frequency transformer is used in the proposed converter, which significantly simplifies the circuit and galvanic insulation design. A dual-phase-shift modulation strategy is proposed to regulate the output power and achieve a simple voltage balancing control. A down-scaled (2 kW/20 kHz) prototype is constructed to demonstrate the proposed converter and verify the control strategy. The experimental results comply with the theoretical analysis well, with the highest power efficiency reaching 97.6%. [ABSTRACT FROM AUTHOR]