Priyanshu Kumar, Gopisetti Manikanta, Mohammed Hasmat Ali
et al.
The continued growth of electric vehicle (EV) deployment has placed increasing emphasis on the development of charging infrastructure that is efficient, reliable, and compliant with safety requirements over a wide range of power levels. In EV charging systems, DC–DC converters work as a key interface for voltage adaptation, power regulation, and battery protection, making the choice of converter topology a crucial design consideration. This study provides a comparative and application-focused review of commonly employed isolated and non-isolated DC–DC converter topologies used in EV charging architectures. The comparison is carried out by examining voltage gain behavior, efficiency tendencies, switching and thermal stress, soft-switching capability, component utilization, control complexity, cost-related aspects, and practical deployment constraints. Fundamental operating principles and representative time-domain simulations are used to highlight relative performance trends of PWM-based and resonant isolated converters under typical charging conditions. Rather than introducing new converter structures or control methods, the objective of this work is to offer practical, design-oriented insights that support informed topology selection. Based on the comparative analysis, non-isolated converters are found to be well suited for low- to medium-power onboard charging applications, whereas isolated resonant converters are more appropriate for high-power and fast-charging systems when safety, scalability, efficiency trends, and system-level implementation factors are considered together.
ABSTRACT Permanent magnet motors (PMMs) are a good choice for many applications due to their merits. These motors include synchronous motors (SMs) and flux modulation motors (FMMs). Their principles of operation depend on the air‐gap permeance harmonics. Permeance harmonics are one of the main factors influencing the performance characteristics of PMMs, including torque, back‐electromotive force (EMF), power factor, flux‐linkage, phase inductance, and flux‐weakening capability. This paper investigates the effect of air‐gap permeance harmonics on PMM performance. For this purpose, the winding function theory (WFT) and the Fourier series are used and various PMM structures having different effective permeance harmonics are presented. Since it is not possible to analyse all these structures, four structures of conventional PMMs are selected as representatives of all the structures. In this paper, the improved analytical modelling of WFT is used, in which the turn function is modified to include the saturation and slot effects. Also, it is possible to calculate the leakage inductance between two stator teeth. Ansys Maxwell software is applied to verify the analytical modelling. Finally, two designs of FMM with different air‐gap permeances are analysed and compared. The superior structure of this FMM is fabricated and tested to confirm the simulation results.
ObjectivesAgainst the backdrop of energy resource scarcity and increasing environmental demands, distributed energy supply technologies, particularly renewable energy technologies, have attracted significant attention due to their high energy efficiency, cost-effectiveness and flexible installation. For remote areas such as plateaus, border regions and islands, which are beyond the coverage of public power grids, islanded microgrids have become the key technology to address electricity access challenges. However, optimizing energy management efficiency remains a major challenge. This paper reviews the two core objectives—economic efficiency and stability—of electric energy in islanded microgrids.MethodsThe current development status and research priorities of islanded microgrids, both domestically and internationally, are analyzed. The basic functions and management objectives of islanded microgrids are discussed. Additionally, the technical approaches for microgrid energy management and three types of control strategies are introduced. Finally, the paper provides a discussion of future research directions for islanded microgrid energy management systems, based on existing technological limitations and the ongoing development of new technologies.ConclusionsThe research results can effectively deal with the volatility and uncertainty of renewable energy and ensure the stable operation of the system. It can effectively reduce the cost of energy storage, improve the efficiency of energy utilization, and achieve higher economic benefits. It can also provide references and insights for the future integration of islanded microgrids with new technologies.
Applications of electric power, Production of electric energy or power. Powerplants. Central stations
Accurate current sensing in rectangular conductors is challenged by mechanical deformations, including eccentricity (X/Y-axis shifts) and inclination (Z-axis tilt), which distort magnetic field distributions and induce measurement errors. To address this, we propose a bio-inspired error compensation strategy integrating an elliptically configured Hall sensor array with a hybrid Grey Wolf Optimizer (GWO)-enhanced backpropagation neural network. The eccentric displacement and tilt angle of the conductor are quantified via a three-dimensional magnetic field reconstruction and current inversion modeling. A dual-stage optimization framework is implemented: first, establishing a BP neural network for real-time conductor state estimations, and second, leveraging the GWO’s swarm intelligence to refine network weights and thresholds, thereby avoiding local optima and enhancing the robustness against asymmetric field patterns. The experimental validation under extreme mechanical deformations (X/Y-eccentricity: ±8 mm; Z-tilt: ±15°) demonstrates the strategy’s efficacy, achieving a 65.07%, 45.74%, and 76.15% error suppression for X-, Y-, and Z-axis deviations. The elliptical configuration reduces the installation footprint by 72.4% compared with conventional circular sensor arrays while maintaining a robust suppression of eccentricity- and tilt-induced errors, proving critical for space-constrained applications, such as electric vehicle powertrains and miniaturized industrial inverters. This work bridges bio-inspired algorithms and adaptive sensing hardware, offering a systematic solution to mechanical deformation-induced errors in high-density power systems.
Abstract In the past decade, model predictive control (MPC) has been widely used in AC motor drives. Although a series of improved MPC strategies have been proposed, researchers are still seeking more effective solutions for different application backgrounds and application requirements to achieve the goals such as algorithm simplification, weighting factor design, parameter robustness enhancement, current/torque ripple suppression, and so on. In this paper, aiming at the above problems, the MPC strategy and its optimisation technology for AC motor drive system are comprehensively reviewed. Firstly, this paper introduces the classical MPC technology with the permanent magnet synchronous motor drive system fed by two‐level voltage source inverter as the control object. Secondly, this paper introduces and discusses the existing MPC optimisation methods from the aspects of current/torque ripple suppression, algorithm simplification, weight factor design and parameter robustness enhancement. Finally, based on the current industrial development requirements for AC motor drive systems and the research status of MPC optimisation methods in the existing literature, the current challenges and future trends of MPC technology are discussed.
With the increasing focus on decarbonisation of the transport sector, it is imperative to consider routes to electrify vehicles beyond those achievable using lithium-ion battery technology. These include heavy goods vehicles and aerospace applications that require propulsion systems that can provide gravimetric energy densities, which are more likely to be delivered by fuel cell systems. While the discussion of light-duty vehicles is abundant in the literature, heavy goods vehicles are under-represented. This paper presents an overview of the electrochemical degradation of a proton exchange membrane fuel cell integrated into a simulated Class 8 heavy goods range-extender fuel cell hybrid electric vehicle operating in urban driving conditions. Electrochemical degradation data such as polarisation curves, cyclic voltammetry values, linear sweep voltammetry values, and electrochemical impedance spectroscopy values were collected and analysed to understand the expected degradation modes in this application. In this application, the proton exchange membrane fuel cell stack power was designed to remain constant to fulfil the mission requirements, with dynamic and peak power demands managed by lithium-ion batteries, which were incorporated into the hybridised powertrain. A single fuel cell or battery cell can either be operated at maximum or nominal power demand, allowing four operational scenarios: maximum fuel cell maximum battery, maximum fuel cell nominal battery, nominal fuel cell maximum battery, and nominal fuel cell nominal battery. Operating scenarios with maximum fuel cell operating power experienced more severe degradation after endurance testing than nominal operating power. A comparison of electrochemical degradation between these operating scenarios was analysed and discussed. By exploring the degradation effects in proton exchange membrane fuel cells, this paper offers insights that will be useful in improving the long-term performance and durability of proton exchange membrane fuel cells in heavy-duty vehicle applications and the design of hybridised powertrains.
In this paper, a heat generator with fluid agitation is developed and experimentally studied. This heat generator can convert kinetic energy from a wind turbine directly to thermal energy through the process of viscous dissipation—a process achieved through the agitation of the working fluid inside a container. In the experimental study, an electric motor (instead of a wind turbine) was used to provide the kinetic energy input to the heat generator. The torque, rotational speed, and temperature rise in the fluid were measured. Using the measured quantities, the efficiency of kinetic energy to sensible heat conversion was calculated. Experiments were conducted to investigate the effects of different impellers, rotational speeds, and working fluids, including distilled water, ethylene glycol (EG), and their respective nanofluids, with <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">A</mi><mi mathvariant="normal">l</mi></mrow><mrow><mn>2</mn></mrow></msub><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></semantics></math></inline-formula> nanoparticles at different concentrations. The study also found that the temperature rise in fluids due to viscous dissipation was influenced by the specific heat of the fluid, suggesting that the heat generator can be optimized for energy storage with high-specific-heat fluids, such as water, or for achieving a higher temperature rise with low-specific-heat fluids, such as ethylene glycol. The experimental results indicated that the heat generator was up to 90% efficient in converting kinetic energy to thermal energy. The study revealed that, for constant power input, the heat dissipation rate depends solely on the vessel’s geometry, not the fluid properties. Optimizing the impeller design and baffles within the vessel is crucial for maximizing power input. For applications, a wind turbine can power this heat generator to provide heat to a house or a commercial building.
<p>The independent advancements in Artificial Intelligence (AI) and robotics have paved the way for significant innovations. The convergence of these technologies, particularly in collaborative robotics (cobots), is revolutionizing various sectors by enhancing human-robot interaction. This paper reviews the integration of AI in robotics, focusing on collaborative robots, their applications, and the ethical considerations involved. We explore key areas such as AI-powered robot control, digital twins, and swarm robotics, highlighting the benefits and challenges of these advancements. Additionally, the paper discusses the future research directions that hold promise for the continued development of intelligent and ethical collaborative robots.</p>
In the novel power system of urban grid, the multiple resources increase and the data collection becomes more difficult, which lead to a higher random missing data rate. It is difficult to meet the demand for refined analysis and decision making. For the frequent missing data problem in the distribution network, a new missing data filling method for power systems based on fluctuation cross-correlation analysis (FCCA) and generative adversarial network (GAN) is proposed in this paper. Firstly, a multi-dimensional feature extraction method for strongly correlated grid data is proposed by fusing FCCA. Secondly, based on kernel principal component analysis (KPCA), the multi-dimensional feature dataset is dimensionally reduced. Finally, an improved GAN structure is designed, which integrates multi-dimensional features of power grid equipment data to reconstruct low dimensional vectors. The missing data is accurately filled in, and the integrity and availability of the new power system measurement data is improved. The algorithm is validated using real grid data, and the proposed method is also tested in a city grid. The results show that the proposed method has higher filling accuracy than the traditional data filling methods. Therefore, it is conformed that in the case of continuous and significant data environment, integrating strong correlation features for data filling has significant advantages in improving the integrity and availability of measurement data.
Abstract The use of rare earth elements (REE) in permanent magnets (PMs) raises problems in several domains. The supply chain of these is fragile, the prices have shown volatility and its manufacturing has a bigger impact on climate change when compared to the manufacturing of other PMs. Instead, ferrite PMs have been researched as an alternative. This alternative shows a relatively higher demagnetisation risk when compared to REE PMs. Thus, a detailed study on permanent demagnetisation during winding faults is crucial. The authors use the finite element method to evaluate different machine designs, developed under mechanical constraints, and explore several strategies to mitigate permanent demagnetisation. Also, the importance of avoiding permanent demagnetisation is changed gradually in the optimisation process. The results show that the protection of the PM and performance optimisation are irreconcilable goals. It also highlights the impact of the stator design in decreasing demagnetisation. Additionally, it is shown that the classic notion of avoiding demagnetisation is an ineffective strategy for designing high‐performance machines with ferrite magnets, and instead, it should be integrated into the optimisation process and weighted according to the application demands.
Abstract This article presents a dual‐winding permanent magnet generator (PMG) system with integrated dual‐channel controller to meet the requirements of high power density, high reliability, and high output performance of aircraft electric power system. The dual‐winding of the PMG are designed to have the same phase spatially, with which the same rotor position can be applied in independent vector control. In addition, a dual‐channel controller is applied to control the two sets of windings, which achieves high‐performance control under normal state and fault‐tolerant control under fault state. The integrated dual‐channel controller integrates two sets of main power circuits into one controller and uses a main control unit, which simplifies the PMG system leading to reduction in the overall volume and weight. Reliability analysis of dual‐winding PMG system is proposed to be compared with that of the single‐winding PMG system. A dual‐winding cooperative control strategy and a fault‐tolerant control strategy are proposed to achieve high‐performance control of DC‐link voltage under normal condition and redundant functions under fault condition. As a result, the reliability of the PMG system is improved. The experimental results validate the effectiveness of the proposed PMG system and the control strategy.
Abstract The segmental translator linear switched reluctance motor (STLSRM) is a special type of linear switched reluctance motor (LSRM) that has more output power than its conventional type. Therefore, it can be a good choice for certain applications. Heat is one of the factors limiting the output in machines. Therefore, predicting the thermal distribution of machine is as important as the magnetic design. A comprehensive thermal model is presented based on the lumped parameter approach for STLSRM, which predicts temperature distribution in different parts of this motor, including slot winding, end‐winding, stator pole, stator yoke, and the moving part. Considering that the proposed thermal model depends on dimensions and materials used in machine, it can be used for other designs of the STLSRM. The presented thermal model is applied to a typical STLSRM and temperature is determined in its different parts. The simulation results are then compared with the results of 3‐D thermal modelling based on the finite element method (FEM) for validation.
This paper introduces a novel compact reconfigurable antenna that utilizes monopole technology and tunable frequencies through switch control. The antenna is fed by a coplanar waveguide (CPW) and features a unique patch design with two L-shaped slots and integrated switches. This inventive design enables remarkable reconfigurability, allowing the antenna to operate within the frequency ranges of [3.8-3.93 GHz], [5.05-5.3 GHz], and [7-7.5 GHz]. These frequency ranges are strategically chosen to align with specific application requirements. The antenna also boasts an almost omnidirectional radiation pattern. The experimental outcomes highlight the efficacy of the proposed antenna, which occupies a compact footprint of 34x35.4 mm², making it particularly well-suited for applications requiring multiband functionality.
Keywords: CPW-fed, multiband antenna, reconfigurable.
Applications of electric power, Electric apparatus and materials. Electric circuits. Electric networks
In recent years, offshore wind power has developed rapidly. It is the most effective way to transmit the wind power far away from the coast through the voltage source converter based high voltage direct current (VSC-HVDC) transmission system. The offshore wind power is usually transmitted by cable, which makes the fault characteristics of VSC-HVDC transmission system more complex than that of overhead transmission system. Based on a symmetrical monopole topology of two-terminal VSC-HVDC offshore wind power transmission project, the mathematical model of the transmission system which contains cables and VSC-HVDC system is simplified. The fault characteristics under typical faults such as single-phase grounding of AC system at converter valve side and single pole grounding of DC cable line are analyzed. Based on the superposition principle, the fault mechanism is analyzed in detail. According to the fault sources of different fault types, different fault circuits are equivalent. The complex influence of the significant capacitance effect of long-distance cables on the fault characteristics of VSC-HVDC systems is obtained. A real time digital simulation model of offshore wind power transmission system through VSC-HVDC is built. The fault mechanism is verified through simulation analysis.
Dingsihao Lyu, Coen Straathof, Thiago Batista Soeiro
et al.
This paper proposes two modulation schemes for Dual Active Bridge (DAB) converters, with the aim of maximizing Zero Voltage Switching (ZVS) operation over a wide operational range. The first is a ZVS-optimized constant frequency modulation scheme, constructed based on the boundary conditions of ZVS operation. This scheme maximizes the number of ZVS events across a broad operational range and is easy to implement. Additionally, a variable frequency modulation scheme is proposed, enabling continuous full ZVS operation for the DAB converter at full power and eliminating the loss of ZVS due to transitioning between modulation regions. This functionality extends the full ZVS range, yielding improved Electromagnetic Interference (EMI) performance and overall power efficiency. The synergy of the proposed modulation schemes is particularly well-suited for applications like off-board Electric Vehicle (EV) charging. Experimental validation, conducted on an 11-kW DAB converter prototype with an output voltage range of 250 V to 950 V, demonstrates the efficacy of the proposed schemes in achieving ZVS and boosting converter efficiency.
Light Fidelity (LiFi) technology has gained attention and is growing rapidly today. Utilizing light as a propagation medium allows LiFi to promise a wider bandwidth than existing Wireless Fidelity (WiFi) technology and enables the implementation of cellular technology to improve bandwidth utilization. In addition, LiFi is very attractive because it can utilize lighting facilities consisting of light-emitting diodes (LEDs). A LiFi system that uses intensity modulation and direct detection requires the signal of orthogonal frequency division multiplexing (OFDM) to have a real and non-negative value; therefore, certain adjustments must be made. The proposed methods for generating unipolar signals vary from adding a direct current, clipping the signal, superposing several unipolar signals, and hybrid methods as in DC-biased optical (DCO)-OFDM, asymmetrically clipped optical (ACO)-OFDM, layered ACO (LACO)-OFDM, and asymmetrically clipped DC-biased optical (ADO)-OFDM, respectively. In this paper, we review and compare various modulation techniques to support the implementation of LiFi systems using commercial LEDs. The main objective is to obtain a modulation technique with good energy efficiency, efficient spectrum utilization, and low computational complexity so that it is easy for us to apply it in experiments on a laboratory scale.
As a representative electrochemical energy storage device, supercapacitors (SCs) feature higher energy density than traditional capacitors and better power density and cycle life compared to lithium-ion batteries, which explains why they are extensively applied in the field of energy storage. While the available reviews are mainly concerned with component materials, state estimation, and industrial applications, there is a shortage of understanding of thermal behaviors and thermal management systems of SCs, which makes this review a timely aide for fulfilling this gap. This review introduces the energy storage mechanisms of SCs, followed by descriptions of current investigations of thermal behaviors. This covers the aspects of heat generation rates for electric double-layer capacitors (EDLCs) and hybrid supercapacitors (HSCs), together with reviewing existing experimental methods to measure and estimate heat generation rates, as well as comparative assessments of multiple heat generation rate models and research on thermal runaway. In addition, there are also overviews of current efforts by researchers in air cooling systems, liquid cooling systems, phase change material cooling systems, and heat pipe cooling systems. Finally, an in-depth discussion is provided regarding the challenges and future work directions for SCs in thermal behaviors and thermal management systems.
Production of electric energy or power. Powerplants. Central stations, Industrial electrochemistry
Mariusz Frączek, Krzysztof Górski, Leszek Wolaniuk
Nowadays, the land forces of the Republic of Poland use mainly two forms of powering their equipment and military devices: by connecting various devices to the national power grid and by diesel-electric generators of individual vehicles. With the first solution, power cuts have to be taken into account. In the latter case, it is necessary to ensure large fuel deliveries on a timely manner. It entails a search for new solutions able to effectively meet the needs of an individual soldier and command posts. It has inspired engineers to work on renewable energy sources. This review paper presents a concept for photovoltaic cells usage and a concept for air turbines used to charge electric power sources of different powers for the individual needs of soldiers and command posts. Examples of solutions for mobile energy systems are presented in the research work. They were verified in terms of their suitability for military applications. The concept of using a personal device to supply power for charging batteries and elements of individual soldier equipment, including low-power radio stations, has been presented as well.
The amplitude of AC line current at the inverter side is affected by DC commutation failure and fluctuates for a short time after single-phase trip.The fluctuation range increases with the increase of the number of DC commutation failures,resulting in the misjudgment of the traditional single-phase fault nature criterion based on the amplitude of the recovery voltage. To solve this problem,a transmission line fault equivalence model is built firstly to evaluate the impact of DC commutation failure on the sound phase voltage. Then the time domain expressions are derived for the disconnected phase voltage during the recovery voltage stage for different fault nature. After that,a single-phase fault nature identification criterion based on time domain voltage integration is proposed,and its effectiveness is verified by PSCAD/EMTDC simulation. The results show that the proposed method has good resistance to transition resistance and DC interference,and the fault nature identification criterion is suitable for DC commutation failure.
ABSTRACT The primary electric power system of ships has been based on the alternating current (AC) system for a long time. However, marine engineers started to question the efficiency of the AC-grid system, which was previously taken for granted and attempted to find a more efficient and eco-friendly electric power distribution system. Following this trend in the marine industry, the direct current (DC) system was adopted for the electric distribution system in ships and combined with the AC-grid. In this regard, this paper presents the technical, economic, and environmental benefits of the DC-grid system for marine applications. Ships that have already applied or plan to apply the DC-grid system are categorized into several types. Additionally, some technical considerations focused on the fault protection topology, the power-sharing (balancing) topology, power quality/stability issues, power source control methods, DC arc flash hazard, and international regulations/standards regarding DC-grid ships are reviewed. Lastly, the prospects of the DC-grid system in ships are addressed with a conclusion.