Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
Axial flux machines have positive sides on the power and torque density profile. However,\nthe price of this profile is paid by the torque ripples and irregular magnetic flux density production.\nTo gather higher efficiency, torque ripples should close to the zero and the stator side iron should be\nunsaturated. Torque ripples mainly occur due to the interaction between the rotor poles and the stator\nteeth. In this study, different rotor poles are investigated in contrast to stator magnetic flux density\nand the torque ripple effects. Since the components of the axial flux machines vary by the radius,\nanalysis of the magnetic resources is more complicated. Thus, 3D-FEA (finite element analysis) is\nused to simulate the effects. The infrastructure of the characteristics which are obtained from the\n3D-FEA analysis is built by the magnetic equivalent circuit (MAGEC) analysis to understand the\nrelationships of the parameters. The principal goal of this research is a smoother distribution of the\nmagnetic flux density and lower torque ripples. As the result, the implementations on the rotor poles\nhave interesting influences on the torque ripple and flux density profiles. The MAGEC and 3D-FEA\nresults validate each other. The torque ripple is reduced and the magnetic flux density is softened on\nAFPM irons. In conclusion, the proposed rotors have good impacts on the motor performance....
This paper deals with the modeling of bond graph buck converter systems. The bond\ngraph formalism, which represents a heterogeneous formalism for physical modeling, is used to\ndesign a sub-model of a power MOSFET and PiN diode switchers. These bond graph models are\nbased on the device�s electrical elements. The application of these models to a bond graph buck\nconverter permit us to obtain an invariant causal structure when the switch devices change state.\nThis paper shows the usefulness of the bond graph device�s modeling to simulate an implicit bond\ngraph buck converter...
The HVDC system has many significant benefits and is widely used around the world. The protection of HVDC system is always\nan issue, which should be solved. This paper presents the working principle of different protection schemes. The advantages and\ndisadvantages of these protection schemes are also introduced. In order to solve the HVDC fault, two protection strategies are\nproposed.One design focusses on the topologies of theHVDC breaker in theHVDC line, such as all-solidHVDC breaker, resonant\nHVDC breaker, and hybrid HVDC breaker. The other design is from the viewpoint of converter topology, which has two types.\nOne type generates the counter-emf in arms, such as full bridgeMMC, hybridMMC, and clamp-doubleMMC. The other type cuts\noff the current path fromthe AC side to the DC side, which is also introduced in this paper. Some performances of these topologies\nare compared, such as switching time and efficiency....
A fault-tolerant control technique is discussed for the Neutral-Point-Clamped (NPC) three-level inverter, which ensures that the\nNPC inverter operates normally even under device failures. A two-level leg is added to the NPC inverter; when the device open\ncircuit fault occurs, the load of this faulty phase is connected to the neutral point of this two-level leg through the bidirectional\nthyristors. An improved Space Vector Pulse Width Modulation (SVPWM) strategy called ââ?¬Å?addition and subtraction substitution\nSVPWMââ?¬Â is proposed to effectively suppress fluctuation in capacitor neutral-point voltages by readjusting the sequence and action\ntime of voltage vectors. The fault-tolerant topology in this paper has the advantages of fewer switching devices and lower circuit\ncosts. Experimental results show that the proposed fault-tolerant system can operate in balance of capacitor neutral-point voltages\nat full output power and the reliability of the inverter is greatly enhanced....
This paper presents a potable renewable energy system. The portable renewable\nenergy power unit is designed from a need. The need is for first response\nteams in remote natural disaster situations to have a reliable source of energy\nto power a small vaccine refrigerator or water purification system and a basic\nsatellite communication system. It is important that such a need is explored as\na practical solution has the potential to save the lives of people in remote\nareas, who would otherwise suffer from a lack of humanitarian aid. Currently\ndiesel generators are the primary source of electricity generation for disaster\nresponders and in most situations work very well and provide a sufficient\namount of electricity to meet the power needs. However, in remote areas road\ninfrastructure is often damaged. In this type of situation getting a constant\nsupply of diesel to the area is an expensive or impractical operation. This is\nwhere the portable renewable energy power unit bridges the gap and allows a\nmore practical solution to be implemented. The specific aim of the work is to\ndesign a compact, stand-alone, product that can be easily transported by\npeople across uneven terrain. It can generate power from wind, solar and hydro\nenergy sources. In this work a new non-isolated multiport DC-DC converter\ntopology for a hybrid energy system in low power applications is proposed.\nThe new topology assimilates multiple renewable energy sources and\npower up multiple loads with different output levels. A complete Solid works\nmodel and FEA analysis, on required components, is completed. The scope of\nthe work encompasses both the electrical and mechanical design of the system....
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