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This paper introduces a cascaded symmetrical non-isolated high step-up voltage gain converter with high efficiency and low voltage stress on components combining a non-isolated buck-boost converter and voltage doubler structure. In the proposed converter, the input source is connected in series to the output load; hence, a part of the source energy is directly delivered from source to load, not through the switching branch, improving efficiency. Furthermore, the appropriately stacked voltage doubler stage not only amplifies the high step-up voltage gain ratio but also considerably diminishes the voltage stress on all semiconductor devices and capacitors. As a result, the costless low internal resistance and low voltage components can be employed for higher efficiency, higher power density, and lower cost. To demonstrate the practicality of the proposed topology, the operating principle is outlined, and the steady-state characteristics are thoroughly analyzed. Furthermore, a 360 W prototype converter has been fabricated to confirm the efficiency of the proposed converter. [ABSTRACT FROM AUTHOR]

In seaports, the automatic Grab-Type Ship Unloader (GTSU) stands out for its ability to automatically load and unload materials, offering the potential for substantial productivity improvement and cost reduction. Developing a fully automatic GTSU, however, presents a unique challenge: the system must autonomously determine the position of the cargo hold and the coordinates of the working point and identify potential hazards during material loading and unloading. This paper proposes AI models designed to detect cargo holds, extract working points, and support collision risk warnings, utilizing both the LiDAR sensor and the camera in the GTSU system. The model for cargo hold detection and collision warning was developed using image data of the cargo hold and grab, employing the You Only Look Once model. Concurrently, the model responsible for extracting the coordinates of working points for the GTSU system was designed by integrating the cargo hold detection and point cloud processing models. After testing the AI models for the lab-scale GTSU, the results show that the cargo hold detection and collision warning models achieve an accuracy of approximately 96% and 90%, respectively. Additionally, the working point coordinates extracted from the sensor system show a deviation of 5–10% compared to traditional measurements. [ABSTRACT FROM AUTHOR]

In this paper, a high-efficiency and low-cost active cell-to-cell balancing circuit for the reuse of electric vehicle (EV) batteries is proposed. In the proposed method, a battery string is divided into two legs to transfer the charge from each cell in one leg to that in the other and a bidirectional CLLC resonant converter is used to transfer energy between the selected cells. Thanks to the proposed structure, the number of bidirectional switches and gate drivers can be reduced by half compared to the conventional direct cell-to-cell topologies, thereby achieving lower cost for the system. The CLLC converter is used to transfer the charge, and it is designed to work at resonant frequencies to achieve zero-voltage zero-current switching (ZVZCS) for all the switches and diodes. Consequently, the system's efficiency can be enhanced, and hence, the fuel economy of the system can also be improved significantly. To verify the performance of the proposed active cell-balancing system, a prototype is implemented for balancing the three EV battery modules that contain twelve lithium-ion batteries from xEV. The maximum efficiency achieved for the charge transfer is 89.4%, and the balancing efficiency is 96.3%. [ABSTRACT FROM AUTHOR]

Faults in wind turbine rotating components contribute significantly to malfunctions and downtime. A prevalent strategy to reduce the Cost of Energy (CoE) in wind energy production focuses on minimizing maintenance expenses associated with these turbine components. An accurate Remaining Useful Life (RUL) diagnosis of these components is crucial for maintenance planning, ensuring uninterrupted energy quality and cost-efficiency. This paper introduces a refined method for RUL prediction of wind turbine rotating components using a Health Index (HI) derived from vibration signals. Performing HI construction by extracting all features from the vibration signal and selecting the best features to build HIs using on Principal Component Analysis (PCA) and some abnormal areas that deviate from the bearing damage trend can be eliminated. After constructing a HI use the similarity model and degradation models to predict RUL. Research results show that this degradation method can provide a reliable means to predict the RUL of wind turbine rotating components based on vibration signals. More importantly, predicting RUL in this way can significantly reduce operating and maintenance costs by providing wind turbine rotating operators with sufficient advance notice to plan repairs or replacements before any component failure occurs. [ABSTRACT FROM AUTHOR]

A saturated iron-core type superconducting fault current limiter (SI-SFCL) can effectively restrict the magnitude of the fault current and alleviate the strain on circuit breakers in DC power systems. Design of a superconducting coil (SC), which is one of the key tasks in the SI-SFCL design, requires guaranteeing a sufficient magnetic field, ensuring optimization of the shape and size, minimizing the wire cost, and satisfying the safety and stability of operation. Generally, finite element method (FEM) is used to calculate and evaluate the operating characteristics of SCs, from which it is possible to determine their optimal design parameters. When the coil is complex and large, the simulation time may range from hours to days, and if input parameters change even slightly, the simulations have to be redone from scratch. Recent advances in deep learning represent the ability to be effective for modeling and optimizing complex problems from training data or in real-time. In this paper, we presented a combination of the FEM simulation and deep Q-network (DQN) algorithm to optimize the SC design of a lab-scale SI-SFCL for a DC power system. The detailed design process and options for the SC of SI-SFCL were proposed. In order to analyze the characteristics related to the electromagnetic properties and operational features of the SC, a 3D FEM model was developed. Then, a DQN model was constructed and integrated with the FEM simulation for training and optimizing the design parameters of the SC in real-time. The obtained results of this study have the potential to effectively optimize the design parameters of large-scale SI-SFCL development for high-voltage DC power systems. [ABSTRACT FROM AUTHOR]

In line with global environmental regulations, the demand for eco-friendly and highly efficient aircraft propulsion systems is increasing. The combination of axial flux motors and superconductors could be a key technology used to address these needs. In this paper, an axial flux high temperature superconducting (HTS) motor for aircraft propulsion was designed and its characteristics were analyzed. A 2G HTS wire with high magnetic flux characteristic was used for the field winding of the 120 kW axial flux HTS motor, and the rotational speed and rated voltage of the motor were 2000 rpm and 220 V, respectively. The axial flux HTS motor implements a revolving armature type for solid cooling of the HTS field coil. The electromagnetic and thermal features of the motor were analyzed and designed utilizing a 3D finite element method program. The HTS coil was maintained at the target temperature by effectively designing the current lead and cooling system to minimize heat loss. These results can be effectively used in the design of propulsion systems for large commercial aircraft in the future as well as for the design of small aircraft with less than 4 seats. [ABSTRACT FROM AUTHOR]

As the demand for eco-friendly energy increases, hydrogen energy and liquid hydrogen storage technologies are being developed as an alternative. Hydrogen has a lower liquefaction point and higher thermal conductivity than nitrogen or neon used in general cryogenic systems. Therefore, the application of hydrogen to cryogenic systems can increase efficiency and stability. This paper describes the design and analysis of a cryogenic cooling system for an electric propulsion system using liquid hydrogen as a refrigerant and energy source. The proposed aviation propulsion system (APS) consists of a hydrogen fuel cell, a battery, a power distribution system, and a motor. For a lab-scale 5 kW superconducting motor using a 2G high-temperature superconducting (HTS) wire, the HTS motor and cooling system were analyzed for electromagnetic and thermal characteristics using a finite element method-based analysis program. The liquid hydrogen-based cooling system consists of a pre-cooling system, a hydrogen liquefaction system, and an HTS coil cooling system. Based on the thermal load analysis results of the HTS coil, the target temperature for hydrogen gas pre-cooling, the number of buffer layers, and the cryo-cooler capacity were selected to minimize the thermal load of the hydrogen liquefaction system. As a result, the hydrogen was stably liquefied, and the temperature of the HTS coil corresponding to the thermal load of the designed lab-scale HTS motor was maintained at 30 K. [ABSTRACT FROM AUTHOR]

The application of cross-linked polyethylene (XLPE) cables to voltage sourced converter (VSC)-based high voltage direct current (HVDC) systems has already been technically verified and has become common, and thermoplastic (TP) is attracting attention as an insulation material for next-generation cables due to the recent development of material-related technologies. However, studies related to TP cables are mainly focused on improving material properties, and studies related to cable systems are insufficient. In this paper, XLPE and TP cables were designed for application to VSC-based HVDC systems, and major characteristics such as electric field distribution and thermal stability were compared and analyzed through overvoltage simulation. The insulation design method of HVDC cable was presented, and the design was performed using XLPE and TP insulation materials. The temperature and electric field profiles of the cables were also analyzed through a finite element method simulation. To analyze the performance of the designed cable, it was simulated with the PSCAD/EMTDC program. Based on the simulation results, the major characteristics of XLPE and TP cables were compared and analyzed. Results showed that in the case of TP cables, insulation properties were excellent, but thermal conductivity was relatively low; therefore, countermeasures are needed. [ABSTRACT FROM AUTHOR]

Predicting the output power of wind generators is essential to improve grid flexibility, which is vulnerable to power supply variability and uncertainty. Digital twins can help predict the output of a wind turbine using a variety of environmental data generated by real-world systems. This paper dealt with the development of a physics-based output prediction model (P-bOPM) for a 10 MW floating offshore wind turbine (FOWT) for a digital twin. The wind power generator dealt with in this paper was modeled considering the NREL 5 MW standard wind turbine with a semi-submersible structure. A P-bOPM of a 10 MW FOWT for a digital twin was designed and simulated using ANSYS Twin Builder. By connecting the P-bOPM developed for the digital twin implementation with an external sensor through TCP/IP communication, it was possible to calculate the output of the wind turbine using real-time field data. As a result of evaluating the P-bOPM for various marine environments, it showed good accuracy. The digital twin equipped with the P-bOPM, which accurately reflects the variability of the offshore wind farm and can predict the output in real time, will be a great help in improving the flexibility of the power system in the future. [ABSTRACT FROM AUTHOR]

This paper proposes a fuzzy-logic-controlled super-conducting magnetic energy storage (SMES) scheme for the stabilization of grid-connected wind-generator systems. The control scheme of SMES is based on a sinusoidal pulsewidth-modulation voltage-source converter and a two-quadrant dc-dc chopper using an insulated-gate bipolar transistor. A comparative study is carried out between the proposed fuzzy-logic-controlled SMES and the fuzzy-logic-based pitch controller to improve the wind-generator stability. Simulation results demonstrate that the performance of the proposed fuzzy-logic-controlled SMES is better than that of the fuzzy-logic-based pitch controller in order to stabilize the wind generator. Index Terms--Fuzzy-logic controller, pitch controller, super-conducting magnetic energy storage (SMES), unsuccessful reclosing, voltage-source converter (VSC), wind-generator stability.

Our previous design procedure for a multistage induction coilgun using the Taguchi method, which determined the turns and the layers of coil, was established and applied to a four-stage induction coilgun capable of launching a 100-kg projectile to a maximum velocity of 27.4 m/s. However, the ignition position, where the pulsed power is applied, is still not optimized yet even though the system purpose was accomplished. In this article, we suggest new design procedure and the control system for a multistage induction coilgun using the Taguchi method, which is capable to determine the ignition position concurrently with the turns and the layers, and the calibrated design was added to overcome the limitation of the Taguchi method. This new procedure is applied to design a four-stage induction coilgun for launching a 1000-kg projectile to a velocity above 20 m/s. The simulation results show that the design model was capable of launching a 1000-kg projectile to a maximum velocity of 26.43 m/s with a 6-kV charging voltage. [ABSTRACT FROM AUTHOR]

For the performance test of photovoltaic (PV) generation systems, actual system apparatuses: a solar panel, converter system, and load facilities should be installed. It is also hardly possible to compare a maximum power point tracking (MPPT) control scheme with others under the same weather and load conditions in an actual PV generation system. One of the possible alternatives is to realize a transient simulation scheme for PV generation systems under real weather conditions of insolation and surface temperature of solar cell. The authors propose a novel real-time simulation method for PV generation systems under real weather conditions using a real-time digital simulator (RTDS). V-I curves of a real PV panel are tested using electric load device, and a hypothetical network of the tested PV panel is created on the RTDS by arranging electrical components from the customized component model libraries. The real weather conditions, insolation, and temperature of the PV panel, are interfaced through the analog input ports of the RTDS for real-time simulation. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation technique, and also show that cost-effective verification of availability and stability of PV generation systems is possible using the built-in simulator. Index Terms--MPPT control, photovoltaic generation systems, real-time simulation, renewable energy, RTDS, solar cell.

Since 2016, Hanwha Defense Corporation has been working on applying electromagnetic launch technologies such as induction coilguns to cold-launch systems that can launch guided missiles. First, a design procedure of a multistage coilgun system based on the pulsed power driven by capacitor banks was developed using the Taguchi method, and a laboratory-scale three-stage coilgun capable of launching a 21.68-kg projectile at a maximum speed of 27.5 m/s was built and the results of the experiment were announced in 2018. In this article, we design, fabricate, and present the experimental results of a pulsed power-based four-stage induction coilgun using the proposed procedure to prove the validity of the electromagnetic launch technology for heavy missile launch. In this experiment, a 100-kg projectile was fired under 4-kV charging conditions, the maximum speed of the projectile was 25 m/s or more, and an efficiency of 15% was achieved without considering the mass of the armature. In this study, by accelerating a 100-kg projectile to 27 m/s, the feasibility of an electromagnetic launcher developed for heavy missile launch was verified. [ABSTRACT FROM AUTHOR]

This paper deals with the possibility of applying superconducting motors and hydrogen fuel cells to electric aviation propulsion systems (APS) for the development of next-generation APS. Instead of the conventional fossil fuel-based power generation system, the APS using hydrogen fuel cells and superconducting motors was conceptually designed. The proposed APS consists of a superconducting motor, a hydrogen fuel cell, a liquid hydrogen tank, and a battery. For specific power comparison, the proposed APS capacity was the same as that of a commercial APS, and the capacity and weight of the hydrogen fuel cell and battery were calculated. The 5 MW superconducting motor was designed and analyzed focusing on magnetic field distribution, thermal load, mechanical stress, efficiency, weight, and specific power. As a result, the proposed APS is expected to reach the level of performance applicable to aircraft in the near future, given the recent development trend of battery and liquid hydrogen technology. These results are expected help in a future-oriented APS design. [ABSTRACT FROM AUTHOR]

In this paper, we describe a cooling system for a high temperature superconducting (HTS) magnet of 10 MW class superconducting wind power generator (SWPG). To cool the HTS magnet below 35 K, a novel neon-helium hybrid cooling system is proposed. Neon cools the heat exchanger based on the thermosiphon principle and a cryogenic blower forcibly circulates helium gas between the heat exchanger, attached to a rotating neon vessel, and the HTS magnets. This cooling system has two advantages: applicability to large rotating HTS magnets and high reliability by removing a cryogenic or a high-pressure rotating coupling. To verify the performance of this cooling system, a lab-scale performance evaluation system(PES) is designed. The PES will be proved by cooling the generated heat and penetrated heat of the HTS magnets during operation. This paper describes the detail design process and the preliminary test results of the fabricated cooling system. [ABSTRACT FROM AUTHOR]

The authors have proposed a performance evaluation system (PES) for large-scale high temperature superconducting (HTS) wind power generators, which produces strong electromagnetic force and high torque due to the high excitation current and the high magnetic load of the machine, based on the computer simulation results. The PES can physically test the structural stability of HTS coils and armatures against high torque and the effect of the magnetic field before mounting the HTS coil on the generator. This paper deals with the design, fabrication, and performance testing of a full-scale HTS coil to be installed in the PES, a performance analysis system for a 10 MW HTS wind power generator. The HTS coil with metal-insulation consists of four racetrack-type single coils with 310 turns per layer. The manufactured HTS coil was tested at 77 K with and without an iron-core. As a result, the critical currents of the tested HTS coils with and without the iron-core were 90 A and 106 A, respectively. Compared to the simulation results, it was found that the magnitude of the magnetic field was the same. These results will be effectively used to study and fabricate high magnetic field coils for HTS applications, as well as the PES being fabricated. [ABSTRACT FROM AUTHOR]

This paper presents some discussions and findings related to the development of the capacitor bank-based pulsed power supply module (PPSM) for an electromagnetic induction coilgun (EIC). Three PPSMs were designed for a three-stage EIC to launch a 21.68-kg projectile at a minimum velocity of 20 m/s. The energy of the PPSM in the first, second, and third stages was 200, 100, and 100 kJ, respectively. Two light-triggered thyristors (LTT) were used as the main switches of the module. The synchronous behaviors of the series LTT, dump circuit, laser diode driver circuit, and protection scheme are analyzed and discussed. The PPSM was built and tested as an EIC system. The simulation results of the PPSM were in agreement with the experimental results. The peak current was about 42 kA at a maximum voltage of 10 kV as in the simulation. The maximum current in the 4-kV launch experiment was 16.47 kA. The velocity of the projectile was more than 25 m/s, which is consistent with the design goal. [ABSTRACT FROM AUTHOR]

In 2016, Hanwha Defense Systems Corporation commenced an electromagnetic launcher program to develop the next-generation “cold-launching” missile launcher system. This system is based on multistage induction coilguns with advantages such as controllability of energy transfer, reusability, and noncontact between the armature and the stators. The system requirement is to launch missiles to a height of 20 m with weight ranging from hundreds of kilograms to several tons. This paper presents the design, fabrication, and experiment results of a laboratory-scale electromagnetic launcher to demonstrate the feasibility of an electromagnetic launcher for heavy missiles. The effectiveness and performance of an electromagnetic launcher developed to launch heavy missiles have been demonstrated by accelerating a 21.68-kg projectile to 20 m/s. [ABSTRACT FROM AUTHOR]