Records with Subject: Electricity & Electrical Devices
Showing records 1 to 25 of 107. [First] Page: 1 2 3 4 5 Last
Hybrid Dynamical Modeling and Control of Permanent Magnet Synchronous Motors: Hardware-in-the-Loop Verification
Mahmoud F. Elmorshedy, Dhafer Almakhles, Mahmoud Abdelrahim
September 21, 2023 (v1)
Keywords: electric vehicles, hybrid dynamical systems, permanent magnet synchronous motor, robust control, sampled-data systems
The stabilization of a permanent magnet synchronous motor using digital controllers requires the design of both the feedback law and an appropriate sampling frequency. Moreover, the design approach must be robust against existing uncertainties, such as disturbances and parameter variations. In this paper, we develop a stabilizing state feedback nonlinear control scheme for the permanent magnet synchronous motor. Moreover, we consider the case where the feedback signal is transmitted over a digital platform, and we derive the stabilizing sampling frequency, such that the stability of the closed-loop system is maintained. We design the controller by emulation, where the closed-loop stability is first established in continuous time; we then take into account the effect of sampling. The feedback law consists of two parts: feedback linearization and robust linear quadratic regulator for the linearized mode. The robustness is achieved by augmenting the state space model, with additional stat... [more]
Observer-Based Control of Inductive Wireless Power Transfer System Using Genetic Algorithm
Mahmoud Abdelrahim, Dhafer Almakhles
July 13, 2023 (v1)
Keywords: eigenstructure assignment, Genetic Algorithm, linear quadratic regulator, wireless power transfer
In this paper, we studied the feedback stabilization of an inductive power transfer system based on available output measurement. The proposed controller relies on a full-order state observer in order to estimate the unmeasured state. The control design problem is challenging due to the large dimension of the closed-loop system, which requires too many tuning parameters to be determined when conventional control methods are employed. To solve this issue, we propose an LQR methodology based on a genetic algorithm such that the weighing coefficients of the cost function matrices can be automatically computed in an optimized manner. The proposed approach combines the method of eigenstructure assignment and the LQR technique in order to design both the controller and the observer gain matrices. The design methodology provides a systematic way to compute the parameters of the LQR technique for a wireless power transfer system in an optimized manner, which can be a useful design tool for man... [more]
Development of a Process to Recycle NdFeB Permanent Magnets Based on the CaO-Al2O3-Nd2O3 Slag System
Ludwig W. Blenau, Daniel Vogt, Oliver Lonski, Abuzar Abrar, Olga Fabrichnaya, Alexandros Charitos
July 7, 2023 (v1)
Keywords: CALPHAD, Nd-rich minerals, neodymium recycling, pyrometallurgical magnet recycling, REPM recycling, slag system design, thermo-calc
Nd, Pr and Dy are critical raw materials as major components for rare earth permanent magnets (REPM). These are integral for several components placed for example within electric vehicles and wind turbine generators. REE primary production is mainly realized in China (~80%) and no REPM recycling industry has been established. Hydrometallurgical recycling routes lead to iron dissolution (66 wt. % Fe in REPM), while pyrometallurgical approaches that utilize SiO2 risk contaminating the produced iron phase. A two-step process is presented that (i) creates an FeOx-CaO-Al2O3-REE2O3 molten slag at 1500 °C through oxidative smelting and (ii) separates an iron-depleted slag phase (CaO-Al2O3-REE2O3) and a molten iron phase via carbothermic or metallothermic reduction at 1700−2000 °C. The slag has been designed as a selective collector phase and the REE2O3 loading within the bulk slag can reach up 25 wt. % REE2O3 at 1700 °C. The contained minerals within the slag exhibit >40 wt. % REE (a higher R... [more]
Active Disturbance Rejection Control of Five-Phase Motor Based on Parameter Setting of Genetic Algorithm
Rongtao Zeng, Jinghong Zhao, Yiyong Xiong, Xiangyu Luo
July 7, 2023 (v1)
Keywords: active disturbance rejection controller, five-phase induction motor, genetic algorithms, parameter setting
Five-phase induction motors have the characteristics of high torque density, low torque ripple, and flexible control, making them suitable for medium- and low-voltage power supply situations. However, with the expansion of application scenarios, five-phase motors need to cope with increasingly complex operating conditions. Five-phase motors for propeller propulsion will face various complex sea conditions during actual use, and five-phase motors for electric vehicles will also face various complex road conditions and operating requirements during use. Therefore, as a propulsion motor, its speed control system must have strong robustness and anti-disturbance performance. The use of traditional PI algorithms has problems, such as poor adaptability and inability to adapt to various complex working conditions, but the use of an active disturbance rejection controller (ADRC) can effectively solve these problems. However, due to the significant coupling between the variables of induction mot... [more]
Study on a Second-Order Adaptive Sliding-Mode Observer Control Algorithm for the Sensorless Permanent Magnet Synchronous Motor
Guozhong Yao, Yuanpeng Cheng, Zhengjiang Wang, Yuhan Xiao
July 4, 2023 (v1)
Keywords: PMSM, position-sensorless control, second-order adaptive sliding-mode observer algorithm, super-twisting
The control of a permanent magnet synchronous motor (PMSM) without a position sensor based on a sliding-mode observer (SMO) algorithm has a serious jitter problem in the process of motor phase tracking. A second-order adaptive sliding-mode observer algorithm was proposed, and the ideas and principles of the second-order sliding-mode observer algorithm based on the super-twisting algorithm were elaborated. In particular, adaptive estimation with the introduction of back-electromotive force (EMF) was investigated, and the Lyapunov stability criterion was used to determine the convergence properties of the algorithm. The results showed that the second-order adaptive sliding-mode observer algorithm had better jitter suppression and a better phase tracking performance than the traditional sliding-mode observer algorithm. The experimental results showed that when the motor velocity was 800 r/min, the velocity error of the second-order adaptive sliding-mode observer algorithm was 0.57 r/min a... [more]
The Upper Triassic Braided River Thin-Bedded Tight Sandstone in the Yanchang Formation, Ordos Basin: Sedimentary Characteristics, Seismic Forecasting Method, and Implication
Tongyang Lou, Congjun Feng, Mengsi Sun, Zhiqiang Chen
June 13, 2023 (v1)
Keywords: braided river, sandbody architecture, seismic facies, tight sandstone
In the Ordos Basin, Chang 81, a Member of the Yanchang Formation, features the development of braided river thin-bedded tight sandstones. These sandstones constitute one of the main production layers of tight oil and gas in the Yanchang Formation within the basin. This study integrates data from core samples, drilling, and seismic information to identify braided river thin-bedded sandstones in the Chang 81 Member at Daijiaping, Ordos Basin, using a method of constrained correlation between seismic waveform and seismic facies. This approach aids in determining the sedimentary microfacies types and reservoir characteristics of thin-bedded tight sandstones. We establish a quantitative fitting formula for the width-to-thickness ratio of braided channel sand bodies to finely characterize sand body stacking patterns and spatial distribution of thin-bedded tight sandstones in braided channels. Braided delta plain deposits in the Chang 81 Member at Daijiaping mainly comprise four types of sedi... [more]
Grid-Connected Phase-Locked Loop Technology Based on a Cascade Second-Order IIR Filter
Shanwen Ke, Yuren Li
May 26, 2023 (v1)
Keywords: grid-connected inverter, harmonics, IIR filter, phase-locked loop
The moving average filter-based phase-locked loop (MAF-PLL) can obtain grid synchronization signals accurately under adverse grid conditions with a large amount of harmonics due to the high filtering capability of the MAF. However, MAF-PLL cannot achieve a fast dynamic response in the case of frequency drift, phase angle steps, and unbalanced voltage sag. MAF is essentially an FIR filter, and its filtering performance is hard to be adjusted. To address this issue, this paper proposes an alternative to MAF consisting of a set of cascading second-order IIR filters (CIIRF). Based on MAF, CIIRF introduces multiple zeros and poles from the zero−pole replacement perspective, and by changing the position of the poles, the filter performance can be adjusted. To improve the anti-interference ability of PLL based on CIIRF (CIIRF-PLL) in the presence of grid frequency drift, a frequency-adaptive scheme is also proposed. Simulation and experimental results show that CIIRF-PLL can accurately track... [more]
An MV-Connected Ultra-Fast Charging Station Based on MMC and Dual Active Bridge with Multiple dc Buses
Marzio Barresi, Edoardo Ferri, Luigi Piegari
May 24, 2023 (v1)
Keywords: Batteries, dual-active bridge, electric vehicles, modular multilevel converter, storage systems, ultra-fast charging
The diffusion of electric vehicles will be strongly related to the capacity to charge them in short times. To do so, the necessity of widespread fast charging stations arises. However, their intermittent demand represents a challenging load for grid operators. In order to relieve their impact on the electrical grid operation, integrating storage systems in the charging stations represents a potential solution, although it complicates the overall system management. Moreover, standard converter architectures for the MV grid interface require the installation of bulky transformers and filters. In order to cope with the mentioned problems, this paper proposes an ultra-fast charging station topology based on a modular multilevel converter (MMC) structure and dual-active bridge (DAB) converters. Thanks to the multilevel converter properties, the proposed charging station can be directly interfaced with the MV grid without requiring transformers or filters. Additionally, exploiting the degree... [more]
An Easily Scalable Dynamic Wireless Power Transfer System for Electric Vehicles
Jannis Noeren, Nejila Parspour, Lukas Elbracht
May 24, 2023 (v1)
Keywords: dynamic wireless charging, electric vehicles, inductive power transfer, inverters, wireless power transfer
This article deals with a LCC-LCC compensated dynamic wireless power transfer system for electric vehicle charging applications. The presented prototype system allows for a power transfer of about 10 kW at 20 cm coil copper to copper distance. With just one circular pickup coil and a very straightforward control scheme, a new coil arrangement enables a seamless power transfer. Furthermore, the system’s design power level is easily adjustable by the size of the the pickup coil. The hardware architecture as well as the software functionality are described in detail. A 20 m test track was built up according to the outlined principle. By measuring the transmitted power, the efficiency and the interference between the primary segments and its effect on the inverter currents are examined. The results show an effective DC to DC efficiency in the range of 91 to 92% and a power fluctuation of approximately 25%.
Research on Electromagnetic Vibration Characteristics of a Permanent Magnet Synchronous Motor Based on Multi-Physical Field Coupling
Dongwen Wang, Wei Yang, Jiafeng Yang, Kongming Jiang, Yang Fu
May 24, 2023 (v1)
Keywords: multi-physics field coupling, PMSM, vibration characteristics
Background and Purpose: The stator vibration characteristics are comprehensively mastered by considering the influence of winding and the housing structure on the stator modes. This effect is neglected in the research field of electromagnetic vibration of permanent magnet synchronous motors (PMSMs). Methods: The radial air-gap flux density equations and PMSM’s electromagnetic force density are derived, and then the harmonic characteristics of electromagnetic force density are studied. An equivalent finite element model of the stator is proposed that investigates the impacts of the winding and stator housing rules on the stator modal frequency. Finally, the harmonic response and acoustic analyses of electromagnetic vibration are carried out based on multi-physics field coupling. Results: The equivalent radiated power distribution laws and acoustic field of motor electromagnetic vibration under transient operating conditions are obtained. The theoretical analysis results are consistent w... [more]
Gallium Nitride Power Devices in Power Electronics Applications: State of Art and Perspectives
Salvatore Musumeci, Vincenzo Barba
May 24, 2023 (v1)
Keywords: cascode, depletion mode, enhancement mode, GaN FET, HEMT, LIDAR, SiC MOSFET, super-junction MOSFET, WBG
High-electron-mobility transistors based on gallium nitride technology are the most recently developed power electronics devices involved in power electronics applications. This article critically overviews the advantages and drawbacks of these enhanced, wide-bandgap devices compared with the silicon and silicon carbide MOSFETs used in power converters. High-voltage and low-voltage device applications are discussed to indicate the most suitable area of use for these innovative power switches and to provide perspective for the future. A general survey on the applications of gallium nitride technology in DC-DC and DC-AC converters is carried out, considering the improvements and the issues expected for the higher switching transient speed achievable.
Improving the Accuracy of Digital Unbalanced Impedance Bridges
Kamil Kontorski, Ryszard Rybski, Janusz Kaczmarek
May 23, 2023 (v1)
Keywords: ac voltage ratio, bridge circuits, impedance measurement, measurement techniques
This article presents an automatic digital unbalanced impedance bridge for comparing two-port impedances: R-R, R-C and C-C. The bridge consists of a two-channel digital source of voltage sinusoidal waveforms supplying the bridge arms and a three-channel precise digitizer, by means of which the complex ratio of the source output voltages and the relative bridge unbalanced voltage are determined. The hardware implementation of the bridge is based on a relatively inexpensive universal data acquisition (DAQ) card by National Instruments, USB-6281, which contains, among others, a multi-channel 18-bit analog-to-digital converter (ADC) and two 16-bit digital-to-analog converters (DAC). Thanks to the new approach to the bridge operation algorithm, consisting in the use of the interpolation method in the comparison process, the influence of the accuracy of the measurement of the bridge unbalanced voltage and some bridge parasitic admittances on the uncertainty of the impedance comparison were m... [more]
Electromagnetic Interference in Cardiac Implantable Electronic Devices Due to Dynamic Wireless Power Systems for Electric Vehicles
Tommaso Campi, Silvano Cruciani, Francesca Maradei, Mauro Feliziani
May 23, 2023 (v1)
Keywords: automotive, cardiac implantable electronic device, dynamic wireless power transfer, electric vehicle, electrified transportation, electromagnetic compatibility, electromagnetic interference, magnetic field, pacemaker, wireless power transfer
Electric vehicles (EV) are now considered the present and future of road transportation to reduce the emission of CO2 into the environment and thus progressively reduce global warming and climate change. However, EVs currently have some weaknesses such as the available range of battery-powered EVs and the recharging time of the batteries. To overcome these problems, some electrification projects have been proposed for road transportation such as the dynamic wireless power transfer (DWPT), where an EV charges as it moves along an electrified lane using magneto-resonant coupling between short tracks mounted on the road pavement and the vehicle’s onboard pickup coils. While the results are encouraging from an electrical point of view, there is concern regarding the magnetic field in the environment produced by the DWPT coils, which can produce adverse health effects in humans and electromagnetic interference (EMI) in electronic devices. The latter also includes implantable medical devices... [more]
A Bridgeless Cuk-BB-Converter-Based BLDCM Drive for MEV Applications
Tanmay Shukla, Srete Nikolovski
May 23, 2023 (v1)
Keywords: bridgeless Cuk-buckboost (BL-Cuk-BB) converter, brushless DC motor (BLDCM), DICM (discontinuous inductor current mode), power quality (PQ), voltage source inverter (VSI)
This article presents a brushless DC motor (BLDCM) drive for a maritime electric vehicle (MEV) application. The presented BLDCM drive uses a bridgeless Cuk-buckboost (BL-Cuk-BB) converter for input-side power factor (PF) improvement. The BL-Cuk-BB converter uses the buckboost converter for the negative half-cycles of the input AC voltages and the Cuk converter for the positive half-cycles. In the case of MEVs, the drive systems are generally fed by diesel engine generators (DEGs). The asymmetric BL-Cuk-BB converter is operated in a discontinuous inductor current mode (DICM) in the present work to attain better power quality. The usage of a second-order buckboost converter with a fourth-order Cuk converter results in a decrement in the net order of the system. Additionally, the input inductor of the Cuk converter also participates as the filter component along with capacitor C2 during buckboost converter operation to enhance the power quality. The total component count reduction in the... [more]
The Efficiency of Offshore Wind Energy Companies in the European Countries: A DEA Approach
Dario Maradin, Bojana Olgić Draženović, Saša Čegar
May 23, 2023 (v1)
Keywords: 47 offshore wind energy companies, assessment of allocative efficiency, electricity generation, input-oriented BCC DEA model, nine European countries
Considering environmental issues such as greenhouse gas emissions associated with climate change and the depletion of fossil fuels, one of the possible solutions is the use of renewable energy sources. Wind energy is one of the most competitive and resilient energy sources in the world, which can play an important role in accelerating the global transition to green energy. The purpose of this study is to evaluate the allocative efficiency of 47 offshore wind energy companies in 9 European countries using the input-oriented BCC DEA model. The basic hypothesis is that by evaluating the relative efficiency of offshore wind energy companies in European countries, it is possible to determine a correlation between the results of efficiency between the two observed periods with slight deviations. The empirical results show no significant correlation between the score of relative efficiency and the country where the offshore wind energy company is located. On the other hand, the results are co... [more]
Analytical Investigation of Magnetic Scalar Potentials Oscillation in Spoke PM Flux Modulation Machines
Lutf Ur Rahman, Abdur Rehman, Byungtaek Kim
May 23, 2023 (v1)
Keywords: magneto-motive force, modulation flux, potential oscillation, scalar magnetic potential, spoke PM machines
In this paper, the oscillation phenomena of the scalar magnetic potential of iron pieces of spoke permanent magnet (PM) machines are analyzed and the effects of the oscillation on the air gap flux and back electro-motive force (EMF) are deeply investigated, especially for flux modulation machines such as vernier and flux switching PM (FSPM) machines. To these ends, the formula of the scalar magnetic potential is derived for a generalized spoke PM structure. It reveals that the oscillation phenomena depend on the slot/pole combination, consequently resulting in different behavior according to the machine types such as vernier and FSPM machines. Next, each core’s potential given as a discrete function is developed into a continuous function of an air gap magneto-motive force (MMF) rotating and oscillating through Fourier series expansion. Making use of the developed MMF and the specific permeance of air gap, the equations of air gap flux density and back EMF are derived, which enable acc... [more]
Resonant Mechanism for a Long-Distance Wireless Power Transfer Using Class E PA and GaN HEMT
Ching-Yao Liu, Chih-Chiang Wu, Li-Chuan Tang, Yueh-Tsung Shieh, Wei-Hua Chieng, Edward-Yi Chang
May 23, 2023 (v1)
Keywords: class E power amplifier (PA), coupling coefficient, GaN, resonant wireless power transfer, voltage gain
This paper presents a study on long-distance wireless power transfer (WPT), which formulates the voltage gain in terms of the coupling coefficient between the power transmitting unit (PTU) and the power receiving unit (PRU) coils. It is proposed that maximum power transfer efficiency (PTE) can be reached when maximum voltage gain is achieved under a matching condition between the coil quality factor and the coupling coefficient. In order to achieve maximum power delivered to load (PDL), we need to elevate the input voltage as high as the high breakdown-voltage of gallium nitride (GaN) high-electron mobility transistors (HEMT) along with class E amplifier circuit topology. In order to promote voltage gain, knowledge of the coupling coefficient between two coils including the factors of the coil diameter, wire diameter, coil turns, and the coil resistance are derived. It was observed that a lower coil resistance leads to a reduced parallel quality, which facilitates long-distance wireles... [more]
A Study of a Generalized Photovoltaic System with MPPT Using Perturb and Observer Algorithms under Varying Conditions
Zulfiqar Ali, Syed Zagam Abbas, Anzar Mahmood, Syed Wajahat Ali, Syed Bilal Javed, Chun-Lien Su
May 23, 2023 (v1)
Keywords: boost converter, MPPT, perturb and observe (P&O), photovoltaic module, Renewable and Sustainable Energy, space vector pulse width modulation
In recent years, renewable energy (RE) has shown promise as a sustainable solution to the rising energy demand worldwide. Photovoltaic (PV) technology has emerged as a highly viable RE alternative. The majority of PV schemes use specific PV models with specified parameters. This study proposes a PV model with generic specifications, a PV array, a DC/DC converter, a DC/AC inverter, maximum power point tracking (MPPT), and grid synchronization using a feedback control system under the MATLAB/Simulink environment. Various MPPT techniques have been adapted to track the PV’s maximum power point (MPP); however, there are various uncertainties. To address these challenges, this paper presented a perturb and observe (P&O) strategy to track the MPP of PV systems reliably. The MPP of a PV system varies according to meteorological order, such as solar radiation and cell temperature. The MPPT primarily gathers the maximum current and voltage of the PV array and provides them to the load using a bo... [more]
The Design and Fabrication of Multiple-Transmitter Coils and Single-Receiver Coils for a Wireless Power Transfer System to Charge a 3s LiPo Drone’s Battery
Ahmed O. MohamedZain, Lee Wei Hou, Huangshen Chua, Kianmeng Yap, Lau Kim Boon
May 23, 2023 (v1)
Keywords: drones, inductive power transfer, lithium polymer battery, wireless power receiver, wireless power transfer, wireless power transmitter
Recent research has shown an increasing interest in wireless power transfer (WPT) technology for drone batteries. The inconvenience of wired charging, especially for drones, is a huge obstacle. In this research project, a WPT platform was proposed by applying four transmitting coils and a single receiving coil. To meet the industrial standards required for transmitter Tx and receiver Rx, a calculation of the parameters was implemented. An H-bridge MOSFET was used as a DC−AC inverter, a bridge diode was used as an AC−DC rectifier, and a Pi low pass filter was added to the receiver circuit design to filter the high-frequency noise. Experimental investigations were conducted to study the maximum power and power efficiency of the coil’s alignment. The focus of this article was to design and fabricate workable multiple-transmitter coils and a single-receiver coil for a wireless power transfer system, in order to charge a 3S LiPo drone’s battery. It not only covers an overview of wireless po... [more]
Design and Optimization of an Asymmetric Rotor IPM Motor with High Demagnetization Prevention Capability and Robust Torque Performance
Ling Ding, Yuan Cheng, Tianxu Zhao, Kai Yao, Yao Wang, Shumei Cui
May 23, 2023 (v1)
Keywords: asymmetric rotor interior permanent magnet motor, manufacturing uncertainties, multi-objective optimization, permanent magnet demagnetization, torque performance robustness
In this paper, an asymmetric rotor interior permanent magnet (ARIPM) motor with high demagnetization prevention capability and robust torque performance is proposed. The key contribution of this paper lies in two aspects. On the one hand, a novel asymmetric rotor with a shifted magnet axis is proposed to improve the demagnetization prevention capability and torque density. In order to obtain a proper asymmetric rotor topology of the ARIPM motor, the multi-physical performances, especially the PM demagnetization characteristics of five types of PM arrangements, are analyzed. Furthermore, an asymmetric rotor with V- and VV-type PM arrangement is preliminarily designed, considering the multi-physical performance balance and the potentially high anti-demagnetization ability. On the other hand, it is found that the asymmetric rotor structure can not only improve the nominal value of motor performance but also can enhance the resistance to the influence of manufacturing uncertainties. Theref... [more]
Grid-Connected Converters: A Brief Survey of Topologies, Output Filters, Current Control, and Weak Grids Operation
Guilherme V. Hollweg, Shahid A. Khan, Shivam Chaturvedi, Yaoyu Fan, Mengqi Wang, Wencong Su
May 23, 2023 (v1)
Keywords: active damping, current control, grid-connected converters, LCL, output filters, passive damping, topologies, weak grids
Grid-connected converters (GCCs) are used extensively for the integration of DC power sources with AC power sources. However, since it is a complex topic, there are many possibilities for regulating grid-injected currents, as well as different modulation techniques for generating full-bridge PWM voltages. The control techniques are directly related to the type of output filter, as well as to the topology of the converter, since a complex plant can require more sophisticated controllers to keep the system stable, and with good regulation performance. Furthermore, a discussion of the applicability of these converters in weak and very weak grids with high inductance content has recently been growing, which adds a greater degree of complexity to the control structure of the converter. In this brief overview are outlined some topics about topologies, output filters, and control, focusing on the current regulation of grid-connected converters. In addition, a discussion of the main challenges... [more]
Electrical Phenomena on Fully Airborne Vertical Electric Antennas in Extreme Weather Conditions
Tomasz Aleksander Miś, Józef Modelski
May 2, 2023 (v1)
Keywords: airborne, balloon, cloud, storm, VED, VLF
This is a conference extension of the paper ‘Investigation on the mature storm cloud’s electric field using long airborne antennas’. The use of vertical antennas (including the VEDs—Vertical Electric Dipoles), lifted up by aerostats to high altitudes without being anchored to the ground, presents numerous advantages in comparison with large terrestrial VLF (Very Low Frequency) antenna structures. A slow-moving floating-earth conductor—a vertical wire antenna—is subjected to intense electrification mechanisms in the atmosphere and inside the cloud layers, producing additional risks for the transmitter and the flight train itself. The electrical potential achieved in this process is, therefore, compared with the flashover voltages over the antenna’s upper fixing point, defining the voltage margins at which the VLF transmitter is able to operate. The electrification processes are also compared to the model based on experimental data on the occurrence of corona discharges over a long, vert... [more]
Damped AC Testing and Diagnosis of Wind Farm HVAC Long-Length Cable Circuits
Edward Gulski, George J. Anders, Rogier Jongen, Jaroslaw Parciak
May 2, 2023 (v1)
Keywords: asset management, condition-based maintenance, damped AC voltage, dissipation factor measurement, failures, insulation testing, on- and offshore wind farm installations, partial discharge measurement, power cables, reliability
Many new HVAC power cable installations on wind farms, both on- and offshore, have long lengths. In contrast to traditional power cable connections of a few kilometers, the failures of those systems usually result in much higher repair and unsupplied energy costs. To support the quality assurance of newly installed cable systems as well as to create a sound basis for condition-based maintenance, this paper discusses the technical challenges of the field testing of long-length power cable systems using a damped AC testing method and also discusses the best practical applications for the testing and diagnosis of these wind farm HVAC cable systems.
Analysis of a Single-Phase Transformerless Bidirectional PFC
Mei Liang, Pengyu Jia, Tengfei Guo
May 2, 2023 (v1)
Keywords: common-mode (CM) leakage current, LCL filter, modulation, power factor corrector (PFC)
This paper presents a single-phase transformerless bidirectional power factor corrector (PFC). A capacitor is inserted into a conventional full-bridge PFC by connecting the ac line terminal and a terminal of DC voltage. The functions of this inserted capacitor have two roles: to bypass the common-mode leakage current from the stray capacitor; to form an LCL filter to reduce the inductor current ripple. A hybrid modulation method is employed in this PFC. The unipolar switching scheme is applied to modulate the PFC, which can achieve high efficiency. Meanwhile, an additional modulation is inserted into the blank time of low-frequency switches to decrease the changing speed of the voltage on the inserted capacitor, and to decrease the spike on the inductor current and leakage current. The performance of the PFC is experimentally verified using a 5 kW prototype.
Extension and Correction of Budeanu Power Theory Based on Currents’ Physical Components (CPC) Theory for Single-Phase Systems
Zbigniew Sołjan, Maciej Zajkowski
May 2, 2023 (v1)
Keywords: Budeanu theory, currents’ physical components (CPC) theory, equivalent parameters, nonsinusoidal systems, single-phase systems
In 1927, the most recognized power theory in the frequency domain was proposed by Budeanu. The second power theory in the frequency domain, which is currently catching a lot of supporters, is the approach proposed by Czarnecki. Both theories have common features in the form of the description of active power and are completely different in terms of the description and interpretation of reactive power. This article presents the possibility of using mutual elements of both approaches: thus, it is possible to interpret the physical meaning of the reactive power (reactive current) proposed by Budeanu and the power before the deformation obtained from the mathematical description.
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