Records with Subject: Interdisciplinary
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Electrical Power and Energy Systems for Transportation Applications
Paul Stewart, Chris Bingham
January 7, 2019 (v1)
This book contains the successful invited submissions [1⁻25] to a Special Issue of Energies on the subject area of “Electrical Power and Energy Systems for Transportation Applications”.
An Experimental Study of Pile-Supported OWC-Type Breakwaters: Energy Extraction and Vortex-Induced Energy Loss
Fang He, Mingjia Li, Zhenhua Huang
January 7, 2019 (v1)
Keywords: experimental study, orifice characteristics, oscillating water column, pile-supported breakwater, pneumatic damping, vortex-induced energy loss, wave energy dissipation, wave energy extraction
Integrating wave energy converters with breakwaters is a promising concept for wave energy utilization. On the basis of fulfilling the wave protection demands, pile-supported Oscillating Water Column (OWC)-type breakwaters can also meet the local needs of electricity far from the lands. In the present study, the wave energy extraction and vortex-induced energy loss of pile-supported OWC-type breakwaters were analyzed based on a two-point measurement method. The importance of energy extraction and vortex-induced energy loss on the wave energy dissipation of pile-supported OWC-type breakwaters were experimentally investigated. It was found that the trends of energy extraction and vortex-induced energy loss were generally correlated. The effects of the pneumatic damping induced by top opening affected the vortex-induced energy loss more than the energy extraction. Results showed that a larger pneumatic damping was preferable for the purpose of increasing energy extraction, whereas for a s... [more]
Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash
Zhiliang Chen, Shengyong Lu, Qiongjing Mao, Alfons Buekens, Wei Chang, Xu Wang, Jianhua Yan
January 7, 2019 (v1)
Keywords: ball milling, heavy metals, MSWI fly ash, stabilization, water washing
Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization) of heavy metals in municipal solid waste incineration (MSWI) fly ash. Three heavy metals (Cu, Cr, Pb) loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a signi... [more]
Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak
Alessandro Lampasi, Giuseppe Maffia, Franco Alladio, Luca Boncagni, Federica Causa, Edmondo Giovannozzi, Luigi Andrea Grosso, Alessandro Mancuso, Paolo Micozzi, Valerio Piergotti, Giuliano Rocchi, Alessandro Sibio, Benedetto Tilia, Vincenzo Zanza
January 7, 2019 (v1)
Keywords: nuclear fusion, pinch, plasma physics, power converters and inverters, power plants, power supply, spherical tokamak, sustainable energy sources
Plasma properties can be useful in a wide spectrum of applications. Experimental projects on controlled nuclear fusion are the most challenging of these applications and, at the same time, the best way to approach plasma science. Since nuclear fusion reactors can ensure a large-scale, safe, environmentally-friendly and virtually inexhaustible source of energy, several fusion-oriented megaprojects and innovative companies are appearing all over the world. PROTO-SPHERA (Spherical Plasma for HElicity Relaxation Assessment) is the first plasma project with a simply connected configuration, namely not requiring additional objects inside the plasma volume. This is obtained by a plasma arc, shaped as a screw pinch, acting as the centerpost of a spherical torus with minimal aspect ratio. Due to its intrinsic physical, engineering and economic advantages, this new approach is attractive also on an industrial scale and with several developments that still needs to be explored. This paper present... [more]
Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams
Yiyu Lu, Yugang Cheng, Zhaolong Ge, Liang Cheng, Shaojie Zuo, Jianyu Zhong
November 27, 2018 (v1)
Keywords: acoustic emissions, crack propagation, hydraulic fracturing (HF), initiation location
When drilling coal-bearing sequences to enhance coal seam permeability by hydraulic fracturing (HF), the location where fractures are initiated is important. To date, most research on fracture initiation has studied the problem in two dimensions. In this study, a three-dimensional model to assess initiation location is developed. The model analyzes the stress state of both the borehole wall and the coal-rock interface and the model shows that the fracture initiation location is affected by in situ stress, the dip of the coal seam, and the angle between the borehole and the coal seam. How the initiation location changes near different types of geological faults is calculated by assuming typical in situ stresses for the faults. Following these calculations, physical experiments were carried out to emulate cross-measure hydraulic fracturing under stress conditions equivalent to those in the Chongqing Tonghua coal mine, China. Fracture initiation during the experiments was monitored by an... [more]
Stress and Damage Induced Gas Flow Pattern and Permeability Variation of Coal from Songzao Coalfield in Southwest China
Minghui Li, Jie Cao, Wenpu Li
November 27, 2018 (v1)
Keywords: coal mine methane, coal permeability, Darcy’s law, effective stress, gas flow pattern
The permeability of coal is a critical parameter in estimating the performance of coal reservoirs. Darcy’s law describes the flow pattern that the permeability has a linear relationship with the flow velocity. However, the stress induced deformation and damage can significantly influence the gas flow pattern and permeability of coal. Coals from Songzao coalfield in Chongqing, southwest China were collected for the study. The gas flow velocities under different injection gas pressures and effective stresses in the intact coal and damaged coal were tested using helium, incorporating the role of gas flow pattern on the permeability of coal. The relationships between the flow velocity and square of gas pressure gradient were discussed, which can help us to investigate the transformation conditions of gas linear flow and gas nonlinear flow in the coal. The results showed that the gas flow in the intact coal existed pseudo-initial flow rate under low effective stress. The low-velocity non-Da... [more]
A Comparative Computational Fluid Dynamics Study on an Innovative Exhaust Air Energy Recovery Wind Turbine Generator
Seyedsaeed Tabatabaeikia, Nik Nazri Bin Nik-Ghazali, Wen Tong Chong, Behzad Shahizare, Ahmad Fazlizan, Alireza Esmaeilzadeh, Nima Izadyar
November 27, 2018 (v1)
Keywords: building integrated, computational fluid dynamics (CFD), exhaust air recovery systems, guide vane, turbulence model, vertical axis wind turbine
Recovering energy from exhaust air systems of building cooling towers is an innovative idea. A specific wind turbine generator was designed in order to achieve this goal. This device consists of two Giromill vertical axis wind turbines (VAWT) combined with four guide vanes and two diffuser plates. It was clear from previous literatures that no comprehensive flow behavior study had been carried out on this innovative device. Therefore, the working principle of this design was simulated using the Analysis System (ANSYS) Fluent computational fluid dynamics (CFD) package and the results were compared to experimental ones. It was perceived from the results that by introducing the diffusers and then the guide vanes, the overall power output of the wind turbine was improved by approximately 5% and 34%, respectively, compared to using VAWT alone. In the case of the diffusers, the optimum angle was found to be 7°, while for guide vanes A and B, it was 70° and 60° respectively. These results wer... [more]
A Transformerless Medium Voltage Multiphase Motor Drive System
Dan Wang, Jiawei Yang, Zhu Chen, Chengxiong Mao, Jiming Lu
November 27, 2018 (v1)
Keywords: cascaded H-bridge converter, motor drive, multiphase motor, PD-PWM, transformerless
A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV) multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP), a complete improved Phase Disposition Pulse Width Modulation (PD-PWM) method is developed to ensure the individual DC-lin... [more]
Cooling Performance Characteristics of the Stack Thermal Management System for Fuel Cell Electric Vehicles under Actual Driving Conditions
Ho-Seong Lee, Choong-Won Cho, Jae-Hyeong Seo, Moo-Yeon Lee
November 27, 2018 (v1)
Keywords: fuel cell electric vehicle, initial temperature difference, radiator, stack, thermal management system
The cooling performance of the stack radiator of a fuel cell electric vehicle was evaluated under various actual road driving conditions, such as highway and uphill travel. The thermal stability was then optimized, thereby ensuring stable operation of the stack thermal management system. The coolant inlet temperature of the radiator in the highway mode was lower than that associated with the uphill mode because the corresponding frontal air velocity was higher than obtained in the uphill mode. In both the highway and uphill modes, the coolant temperatures of the radiator, operated under actual road driving conditions, were lower than the allowable limit (80 °C); this is the maximum temperature at which stable operation of the stack thermal management system of the fuel cell electric vehicle could be maintained. Furthermore, under actual road driving conditions in uphill mode, the initial temperature difference (ITD) between the coolant temperature and air temperature of the system was... [more]
Progress in Heat Pump Air Conditioning Systems for Electric Vehicles—A Review
Qinghong Peng, Qungui Du
November 27, 2018 (v1)
Keywords: air conditioning, electric vehicle, heat pump, heat source
Electric vehicles have become increasingly popular in recent years due to our limited natural resources. As a result, interest in climate control systems for electric vehicles is rising rapidly. According to a variety of research sources, the heat pump air conditioning system seems to be a potential climate control system for electric vehicles. In this paper, an extensive literature review has been performed on the progress in heat pump air conditioning systems for electric vehicles. First, a review of applications of alternative environmentally friendly refrigerants in electric vehicles is introduced. This is followed by a review of other advanced technologies, such as the inverter technology, innovative components and the system structure of the heat pump air conditioning system for electric vehicles. Lastly, recent developments in multiple source heat pump systems are presented. The use of these advanced technologies can provide not only sufficient refrigerating capacity for the ele... [more]
Development of an ICE-Based Micro-CHP System Based on a Stirling Engine; Methodology for a Comparative Study of its Performance and Sensitivity Analysis in Recreational Sailing Boats in Different European Climates
Guillermo Rey, Carlos Ulloa, Jose Luis Míguez, Elena Arce
November 27, 2018 (v1)
Keywords: internal combustion engine, micro combined heating and power (micro-CHP), recreational sailing boat, sensitivity analysis, stirling engine, TRNSYS
Micro combined heating and power (micro-CHP) systems are becoming more than important, and even essential, if we pretend to take full advantage of available energy. The efficiency of this kind of systems reaches 90% and important savings in energy transport processes can occur. In this research, an internal combustion engine (ICE)-based micro-CHP system was developed and tested under specific constraints. The system uses a two cylinder Otto engine as prime mover, coupled to an electrical alternator, and it uses exhaust gases and engine cooling circuit heat. The micro-CHP system was developed to match the electrical power of a typical Stirling engine (SE)-based micro-CHP unit, in order to later compare both systems’ performance under similar circumstances. Different operating modes were tested under different engine speeds, in order to find the optimum operating point. A stand-alone portable application of this system was performed using recreational sailing boats as mobile homes. Speci... [more]
Performance Evaluation of Radiator and Radiant Floor Heating Systems for an Office Room Connected to a Ground-Coupled Heat Pump
Ioan Sarbu, Calin Sebarchievici
November 27, 2018 (v1)
Keywords: Energy Efficiency, GCHP, geothermal energy, radiant floor heating, radiator heating, simulation models
A ground-coupled heat pump (GCHP) system used to provide the space heating for an office room is a renewable, high performance technology. This paper discusses vapour compression-based HP systems, briefly describing the thermodynamic cycle calculations, as well as the coefficient of performance (COP) and CO₂ emissions of a HP with an electro-compressor and compares different heating systems in terms of energy consumption, thermal comfort and environmental impact. It is focused on an experimental study performed to test the energy efficiency of the radiator or radiant floor heating system for an office room connected to a GCHP. The main performance parameters (COP and CO₂ emissions) are obtained for one month of operation of the GCHP system, and a comparative analysis of these parameters is presented. Additionally, two numerical simulation models of useful thermal energy and the system COP in heating mode are developed using the Transient Systems Simulation (TRNSYS) software. Finally, t... [more]
Reduced-Capacity Inrush Current Suppressor Using a Matrix Converter in a Wind Power Generation System with Squirrel-Cage Induction Machines
Sho Shibata, Hiroaki Yamada, Toshihiko Tanaka, Masayuki Okamoto
November 27, 2018 (v1)
Keywords: inrush current, matrix converter, voltage sag, wind power generation
This paper describes the reduced capacity of the inrush current suppressor using a matrix converter (MC) in a large-capacity wind power generation system (WPGS) with two squirrel-cage induction machines (SCIMs). These SCIMs are switched over depending on the wind speed. The input side of the MC is connected to the source in parallel. The output side of the MC is connected in series with the SCIM through matching transformers. The modulation method of the MC used is direct duty ratio pulse width modulation. The reference output voltage of the MC is decided by multiplying the SCIM current with the variable control gain. Therefore, the MC performs as resistors for the inrush current. Digital computer simulation is implemented to confirm the validity and practicability of the proposed inrush current suppressor using PSCAD/EMTDC (power system computer-aided design/electromagnetic transients including DC). Furthermore, the equivalent resistance of the MC is decided by the relationship betwee... [more]
An Embedded System in Smart Inverters for Power Quality and Safety Functionality
Rafael Real-Calvo, Antonio Moreno-Munoz, Juan J. Gonzalez-De-La-Rosa, Victor Pallares-Lopez, Miguel J. Gonzalez-Redondo, Isabel M. Moreno-Garcia
November 27, 2018 (v1)
Keywords: distributed energy resource, embedded system, power quality, smart grid, smart inverter
The electricity sector is undergoing an evolution that demands the development of a network model with a high level of intelligence, known as a Smart Grid. One of the factors accelerating these changes is the development and implementation of renewable energy. In particular, increased photovoltaic generation can affect the network’s stability. One line of action is to provide inverters with a management capacity that enables them to act upon the grid in order to compensate for these problems. This paper describes the design and development of a prototype embedded system able to integrate with a photovoltaic inverter and provide it with multifunctional ability in order to analyze power quality and operate with protection. The most important subsystems of this prototype are described, indicating their operating fundamentals. This prototype has been tested with class A protocols according to IEC 61000-4-30 and IEC 62586-2. Tests have also been carried out to validate the response time in... [more]
Application of Breathing Architectural Members to the Natural Ventilation of a Passive Solar House
Kyung-Soon Park, Sang-Woo Kim, Seong-Hwan Yoon
November 27, 2018 (v1)
Keywords: full-size experiment, heat load, natural ventilation, passive
The efficient operation of a passive solar house requires an efficient ventilation system to prevent the loss of energy and provide the required ventilation rates. This paper proposes the use of “breathing architectural members” (BAMs) as passive natural ventilation devices to achieve much improved ventilation and insulation performance compared to mechanical ventilation. Considering the importance of evaluating the ventilation and insulation performances of the members, we also propose numerical models for predicting the heat and air movements afforded by the members. The numerical model was validated by comparison with experimental results. The effectiveness of the BAMs was also verified by installation in houses located in an area with warm climate. For this purpose, chamber experiments were performed using samples of the BAMs, as well as numerical simulations to assess natural ventilation and heat load. The main findings of the study are as follows: (1) the one-dimensional chamber... [more]
Pulse-Based Fast Battery IoT Charger Using Dynamic Frequency and Duty Control Techniques Based on Multi-Sensing of Polarization Curve
Meng Di Yin, Jeonghun Cho, Daejin Park
November 27, 2018 (v1)
Keywords: battery management system (BMS), fast battery charger, frequency and duty control, polarization, pulse width modulation
The pulse-based charging method for battery cells has been recognized as a fast and efficient way to overcome the shortcoming of a slow charging time in distributed battery cells, which is regarded as a connection of cells such as the Internet of Things (IoT). The pulse frequency for controlling the battery charge duration is dynamically controlled within a certain range in order to inject the maximum charge current into the battery cells. The optimal frequency is determined in order to minimize battery impedance. The adaptation of the proposed pulse duty and frequency decreases the concentration of the polarization by sensing the runtime characteristics of battery cells so that it guarantees a certain level of safety in charging the distributed battery cells within the operating temperature range of 5⁻45 °C. The sensed terminal voltage and temperature of battery cells are dynamically monitored while the battery is charging so as to adjust the frequency and duty of the proposed chargin... [more]
Measuring the Dynamic Characteristics of a Low Specific Speed Pump—Turbine Model
Eve Cathrin Walseth, Torbjørn K. Nielsen, Bjørnar Svingen
November 27, 2018 (v1)
Keywords: reversible pump-turbine, stability, transient calculations
This paper presents results from an experiment performed to obtain the dynamic characteristics of a reversible pump-turbine model. The characteristics were measured in an open loop system where the turbine initially was run on low rotational speed before the generator was disconnected allowing the turbine to go towards runaway. The measurements show that the turbine experience damped oscillations in pressure, speed and flow rate around runaway corresponding with presented stability criterion in published literature. Results from the experiment is reproduced by means of transient simulations. A one dimensional analytical turbine model for representation of the pump-turbine is used in the calculations. The simulations show that it is possible to reproduce the physics in the measurement by using a simple analytical model for the pump-turbine as long as the inertia of the water masses in the turbine are modeled correctly.
Enhancement of Fire Safety of an Existing Green Building due to Natural Ventilation
Hong Sheng Huang, Chung Hwei Su, Cheng Bang Li, Ching Yuan Lin, Chun Chou Lin
November 27, 2018 (v1)
Keywords: fire dynamics simulator, fire safety, green building, natural ventilation, stack effect
In recent years, natural ventilation technology is extensively used in order to improve indoor environment quality and reduce power consumption of air-conditioning systems in green buildings. However, the effect of natural ventilation on fires needs to be evaluated carefully, and how to make these energy-saving buildings safe is a topic worth studying. This study uses Fire Dynamics Simulator on some fire safety enhancement measures for an existing green building without installation of a smoke exhaust system. Since the building is located on a school campus, it does not require a smoke exhaust system according to Taiwan fire regulations. Referential results, obtained after a series of improvement strategies are tested, show that kiln natural ventilation can generate a comfortable air flow. Unfortunately, due to the stack effect, hot air and fatal smoke are blown into the evacuation route area behind the room when a fire occurs. The findings showed that there are two feasible improvemen... [more]
Shape Design of the Duct for Tidal Converters Using Both Numerical and Experimental Approaches (pre-2015)
Chul H. Jo, Do Y. Kim, Su J. Hwang, Chan H. Goo
November 27, 2018 (v1)
Keywords: circulation water channel (CWC), duct, experiment, horizontal axis tidal turbine, ocean energy, tidal current power (TCP)
Recently, focus has been placed on ocean energy resources because environmental concerns regarding the exploitation of hydrocarbons are increasing. Among the various ocean energy sources, tidal current power (TCP) is recognized as the most promising energy source in terms of predictability and reliability. The enormous energy potential in TCP fields has been exploited by installing TCP systems. The flow velocity is the most important factor for power estimation of a tidal current power system. The kinetic energy of the flow is proportional to the cube of the flow’s velocity, and velocity is a critical variable in the performance of the system. Since the duct can accelerate the flow velocity, its use could expand the applicable areas of tidal devices to relatively low velocity sites. The inclined angle of the duct and the shapes of inlet and outlet affect the acceleration rates of the flow inside the duct. In addition, the volume of the duct can affect the flow velocity amplification pe... [more]
A Half-Bridge Voltage Balancer with New Controller for Bipolar DC Distribution Systems
Byung-Moon Han
November 27, 2018 (v1)
Keywords: battery energy storage (BES), bipolar DC distribution system, grid-tied converter, half-bridge voltage balancer, photovoltaic (PV) generator, Proportional and Integral (PI) control, super-cap energy storage (SCES)
This paper proposes a half-bridge voltage balancer with a new controller for bipolar DC distribution systems. The proposed control scheme consists of two cascaded Proportional Integral (PI) controls rather than one PI control for balancing the pole voltage. In order to confirm the excellence of voltage balancing performance, a typical bipolar DC distribution system including a half-bridge voltage balancer with proposed controller was analyzed by computer simulations. Experiments with a scaled prototype were also carried out to confirm the simulation results. The half-bridge voltage balancer with proposed controller shows better performance than the half-bridge voltage balancer with one PI control for balancing the pole voltage.
A High-Gain Three-Port Power Converter with Fuel Cell, Battery Sources and Stacked Output for Hybrid Electric Vehicles and DC-Microgrids
Ching-Ming Lai, Ming-Ji Yang
November 27, 2018 (v1)
Keywords: battery, dc-microgrid, fuel cell (FC), high-gain, hybrid electric vehicle (HEV), three-port power converter with stacked output
This paper proposes a novel high-gain three-port power converter with fuel cell (FC), battery sources and stacked output for a hybrid electric vehicle (HEV) connected to a dc-microgrid. In the proposed power converter, the load power can be flexibly distributed between the input sources. Moreover, the charging or discharging of the battery storage device can be controlled effectively using the FC source. The proposed converter has several outputs in series to achieve a high-voltage output, which makes it suitable for interfacing with the HEV and dc-microgrid. On the basis of the charging and discharging states of the battery storage device, two power operation modes are defined. The proposed power converter comprises only one boost inductor integrated with a flyback transformer; the boost and flyback circuit output terminals are stacked to increase the output voltage gain and reduce the voltage stress on the power devices. This paper presents the circuit configuration, operating princi... [more]
Analysis of a Vertical Flat Heat Pipe Using Potassium Working Fluid and a Wick of Compressed Nickel Foam
Geir Hansen, Erling Næss, Kolbeinn Kristjansson
November 27, 2018 (v1)
Keywords: aluminum electrolysis cell, compressed nickel foam wick, heat pipe, hot spot analysis, potassium
Heat at high temperatures, in this work 400⁻650 °C, can be recovered by use of cooling panels/heat pipes in the walls of aluminum electrolysis cells. For this application a flat vertical heat pipe for heat transfer from a unilateral heat source was analyzed theoretically and in the laboratory, with special emphasis on the performance of the wick. In this heat pipe a wick of compressed nickel foam covered only the evaporator surface, and potassium was used as the working fluid. The magnitudes of key thermal resistances were estimated analytically and compared. Operating temperatures and wick performance limits obtained experimentally were compared to predictions. Thermal deformation due to unilateral heat flux was analyzed by the use of COMSOL Multiphysics®. The consequences of hot spots at different locations on the wick were analyzed by use of a numerical 2D model. A vertical rectangular wick was shown to be most vulnerable to hot spots at the upper corners.
Rotor Design for an Efficient Single-Phase Induction Motor for Refrigerator Compressors
Hyun-Jin Ahn, Kang-Won Kim, Joon-Ho Choi, Eui-Sun Kim, Young-Cheol Lim
November 27, 2018 (v1)
Keywords: centrifugal casting, compressor, fill factor, finite element method, pressure die-casting, rotor, single-phase induction motor
This article describes a rotor making technology for the production of high-efficiency single-phase induction motors (SPIMs) to be used in refrigerator compressors. Rotors can have different aluminum fill factors according to the fabrication method. In order to examine the association between the fill factor and the efficiency of the rotor, we analyzed the distribution of magnetic flux density using the finite element method (FEM). Next, we made prototype rotors by conventional casting methods and by the proposed casting method and compared their fill factors. In addition, SPIMs were made using the rotors, and their efficiencies were measured using a dynamometer. Moreover, the SPIMs were put to use in a compressor, for testing, and for each SPIM the refrigerating capacity of the compressor was measured with a calorimeter. Based on the results of the FEM analysis of the magnetic flux density and the experiments, the reliability and validity of the proposed method were proven.
An Efficiency Enhancement Technique for a Wireless Power Transmission System Based on a Multiple Coil Switching Technique
Vijith Vijayakumaran Nair, Jun Rim Choi
November 27, 2018 (v1)
Keywords: coupling coefficient tuning, magnetically-coupled resonators, power transfer efficiency, wireless power transmission
For magnetic-coupled resonator wireless power transmission (WPT) systems, higher power transfer efficiency can be achieved over a greater range in comparison to inductive-coupled WPT systems. However, as the distance between the two near-field resonators varies, the coupling between them changes. The change in coupling would in turn vary the power transfer efficiency. Generally, to maintain high efficiency for varying distances, either frequency tuning or impedance matching are employed. Frequency tuning may not limit the tunable frequency within the Industrial Scientific Medical (ISM) band, and the impedance matching network involves bulky systems. Therefore, to maintain higher transfer efficiency over a wide range of distances, we propose a multiple coil switching wireless power transmission system. The proposed system includes several loop coils with different sizes. Based on the variation of the distance between the transmitter and receiver side, the power is switched to one of the... [more]
A Dual-Consequent-Pole Vernier Memory Machine
Hui Yang, Heyun Lin, Zi-Qiang Zhu, Shuhua Fang, Yunkai Huang
November 27, 2018 (v1)
Keywords: automotive, field modulation, hybrid permanent magnet (PM), memory machine, Vernier machine
This paper proposes a novel dual-consequent-pole Vernier memory machine (DCP-VMM) featuring alternatively arranged NdFeB and low coercive-force (LCF) magnet poles on the rotating and stationary sides, respectively. Due to the presence of LCF magnets that can be repetitively magnetized or demagnetized via a simple current pulse, the extra-high torque density at low-speed, and excellent high-efficient high-speed flux-weakening performance can be simultaneously realized. The configuration and operating principle, as well as the design considerations of the proposed machine are introduced, respectively. The finite element method (FEM) coupled with a nonlinear analytical hysteresis model for LCF magnets is employed to investigate the electromagnetic performance of the machine, which verifies the effectiveness of machine design and the feasibility as a competent candidate for automotive applications.
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