Showing papers on "Magnetic circuit published in 2008"

Spin Wave Magnetic NanoFabric: A New Approach to Spin-Based Logic Circuitry

Abstract: We describe a magnetic nanofabric, which may provide a route to building reconfigurable spin-based logic circuits compatible with conventional electron-based devices. A distinctive feature of magnetic nanofabric is that a bit of information is encoded into the phase of the spin wave signal. This makes it possible to transmit information without the use of electric current and to utilize wave interference for useful logic functionality. The basic elements include voltage-to-spin-wave and wave-to-voltage converters, spin waveguides, a spin wave modulator, and a magnetoelectric cell. We illustrate the performance of the basic elements by experimental data and the results of numerical modeling. The combination of the basic elements leads us to construct magnetic circuits for NOT and majority logic gates. Logic gates such as AND, OR, NAND, and NOR are shown as the combination of NOT and reconfigurable majority gates. Examples of computational architectures such as a multibit processor and a cellular nonlinear network are described. The main advantage of the proposed magnetic nanofabric is its ability to realize logic gates with fewer devices than in CMOS-based circuits. Potentially, the area of the elementary reconfigurable majority gate can be scaled down to 0.1 mum2. We also discuss the disadvantages and limitations of the magnetic nanofabric.

Design Considerations of a Direct Drive Brushless Machine With Concentrated Windings

Abstract: This paper discusses the performance attributes of the open-slot, modular-wound, external-rotor, topology of electrical machine. Combinations of pole and slot numbers are presented for which the winding factor is maximal and torque ripple is minimal. An optimization of the magnetic circuit design of six promising pole-slot configurations is undertaken using a parametric finite element model (FEM) combined with a genetic algorithm (GA). These designs are benchmarked against a conventional 1.5 slots/pole external-rotor brushless dc machine. These candidate electrical machine versions are characterized by having the same external-rotor diameter, total slot area available for the winding and by equal volumes of permanent magnet (PM). Based on the analysis, the most promising motor structure was selected and a prototype wheel-hub motor has been built for application in a small electrical vehicle. Test data from the prototype is used to validate the findings of the initial analyses and practically demonstrate the attributes of the topology.

Inductance Calculations of Permanent-Magnet Synchronous Machines Including Flux Change and Self- and Cross-Saturations

Abstract: Accurate inductance calculation of permanent-magnet synchronous machines is a relevant topic, since the inductances determine a large part of the electrical machine behavior. However, the inductance calculation, as well as the inductance measurement, is never a completely straightforward task when saturation occurs. In this paper, the total flux in the d and q axes are obtained from finite- element method or measurements and therefore include saturation and cross-couplings. The inductances are obtained from analytical post-processing based on an equivalent magnetic circuit. The originality of this method is that it accommodates the changes in the magnet flux and the inductances with the level of saturation. The resulting inductance values are the ones seen by the converter or the grid, as found by a more accurate approach.

Magnetic head and magnetic recording device

Abstract: It is made possible to restrict the variation of the oscillation frequency of a spin torque oscillator placed in the vicinity of the recording magnetic pole. A magnetic head includes: a recording magnetic pole to generate a recording magnetic field; a spin torque oscillator formed in the vicinity of the recording magnetic pole; and a magnetic field applying unit configured to apply a magnetic field to the spin torque oscillator. The magnetic field applied to the spin torque oscillator by the magnetic field applying unit is perpendicular to a recording magnetic field generated from the recording magnetic pole.

Principle of Operation and Feature Investigation of a New Topology of Hybrid Excitation Synchronous Machine

Abstract: We present a new topology of hybrid excitation synchronous machine (HESM) and describe operational principles and features of the new configuration. Using the radial/axial distribution of the magnetic field, we develop an equivalent magnetic circuit model. We obtain magnetic flux, flux density, and induced voltage with various electrical magnetomotive forces by calculating the nonlinear magnetic circuit equation. We studied the Influence on the radial magnetic field of the axial magnetic field by 3-D finite-element method. The results are in good agreement with calculation by our magnetic circuit model. Our findings indicate that the air-gap flux density of a flux-concentrating HESM is high and the magnetic field in the air gap can be successfully regulated. Experimental results of 3 kVA prototype machine verify the feasibility of the structure and the correctness of our analysis.

Three-Dimensional Lumped-Parameter Magnetic Circuit Analysis of Single-Phase Flux-Switching Permanent-Magnet Motor

Abstract: A 3-D lumped-parameter magnetic circuit model is developed for a single-phase flux-switching permanent-magnet motor. Particular attention is given to representing the complex air-gap flux paths by equivalent permeances so as to accurately model the asymmetry in the air-gap field distribution and to determine the back-EMF and inductance waveforms, as well as the average static torque. Leakage fluxes external to the stator outer surface and the end surfaces on the back-EMF waveform are also taken into account. The developed model is used to investigate the influence of the motor axial length and magnet dimensions on the end effect. Good agreement between predicted, finite element-calculated, and measured results is achieved.

Variable magnetic flux drive system

Abstract: A variable magnetic flux motor drive system includes: a variable magnetic flux motor having a variable magnet which is a low-coercive permanent magnet; an inverter that drives the variable magnetic flux motor 1; an inverter as a magnetization unit which supplies a magnetization current for controlling a magnetic flux of the variable magnet; and a boosting unit boosting an input DC voltage to a predetermined target value to output it to the inverter. The variable magnetic flux motor drive system makes it possible to achieve size reduction and high efficiency, while securing a voltage required for supplying a magnetization current when controlling the magnetic flux of the variable magnet.

Characteristic Analysis of Interior Permanent-Magnet Synchronous Motor in Electrohydraulic Power Steering Systems

Abstract: This paper presents design and analysis results of a 2.6-kW interior permanent-magnet synchronous motor developed for an electrohydraulic power steering system. The motor was designed by using the proposed equivalent magnetic circuit model in consideration with a core loss. To analyze motor characteristics by using the equivalent magnetic circuit model, inductance and iron-loss resistance, which are affected critically by magnetic saturation, are obtained by using finite-element analysis. Finally, motor characteristics such as armature current, torque, and efficiency are calculated by the equivalent magnetic circuit model and verified by experimental results.

Thin film perpendicular magnetic recording head, their fabrication process and magnetic disk drive using it

Abstract: Thin film perpendicular magnetic head with a narrow main pole capable of a high recording density in excess of 100 gigabits per square inch and generating a high magnetic recording field, while also being modified to suppress remanent magnetic fields occurring immediately after writing operation. A return path is provided for supplying a magnetic flux to the main pole, and an conductive coil for excitation of the main pole and return path. The main pole has a pole width of 200 nanometers or less, and a magnetic multilayer made up of a high saturation flux density layer and low saturation flux density layer. The low saturation flux density layer and the high saturation flux density suppress remanent magnetization and prevent erasing after writing by utilizing a closed magnetic domain structure in the pole.

Application of Schwarz-Christoffel Mapping to Permanent-Magnet Linear Motor Analysis

Abstract: Several well-known analytical techniques exist for the force profile analysis of permanent-magnet linear synchronous motors. These techniques, however, make significant simplifications in order to obtain the magnetic field distribution in the air gap. From the field distribution, the force profile can be found. These widely used techniques provide a reasonable approximation for force profile analysis, but fail to give really accurate results in the sense of the exact shape of the force profile caused by effects that due to simplification are not fully included. To obtain the exact shape for the force profile in these cases, the computationally expensive finite-element method (FEM) is often applied. In this paper, an elegant semianalytical approach is presented to acquire the force profile. First, the magnetic field distribution in the air gap is determined by means of Schwarz-Christoffel (SC) mapping. The SC mapping allows a slotted structure of the machine to be mapped to a geometrically simpler domain for which analytic solutions are available. Subsequently, the field solution in the slotted structure can be determined by applying the mapping function to the field distribution in the simplified domain. From the resulting field distribution, the force profile is calculated by means of the Maxwell stress tensor. The results are compared with those from the commonly used equivalent magnetic circuit modeling and 2-D FEM software to demonstrate the accuracy which can be reached by application of the SC method.

Optimum Design of Transverse Flux Linear Motor for Weight Reduction and Improvement Thrust Force Using Response Surface Methodology

Abstract: Permanent magnet (PM)-type transverse flux linear motors (TFLMs) are electromagnetic devices which can develop directly powerful linear motion. The unique configuration makes power of output higher than longitudinal motors, but also it makes characteristic analysis difficulties. This paper deals with an effective analysis of PM-type TFLM by 3-D equivalent magnetic circuit network method (EMCNM). This paper presents optimum design of PM-type TFLM to reduce the weight of the machine with the constraints of thrust and detent force using response surface methodology (RSM). RSM was well adapted to make the analytical model of the minimum weight with constraints of thrust and detent forces and enable the objective function to be easily created and a great deal of the time in computation to be saved. Therefore, it is expected that the proposed optimization procedure using RSM can be easily utilized to solve the optimization problem of electric machines.

AMR current measurement device

Abstract: Many devices for contactless current measurement employ a magnetic circuit (flux concentrator) formed by a ferromagnetic ring (or yoke) with the sensor (typically Hall element) placed in the air gap. Thus the impact of the ambient magnetic fields (i.e. other than caused by the measured current) is highly reduced and the sensitivity of the device is increased. However, the linearity of such measurement can be affected by the non-linear behavior of the magnetic material of the yoke. A device for the contactless current measurement with anisotropic magnetoresistive sensors (AMR) has been developed. As the AMRs are much more sensitive than classically used Hall sensors, no magnetic concentrator is needed. The realized device reaches so far the linearity error of ±0.05% in the current range of ±8 A, i.e. the absolute resolution is 4 mA.

Performance Improvement of PM Synchronous Motor by Using Soft Magnetic Composite Material

Abstract: The paper presents some aspects of soft magnetic composite (SMC) material application in electrical machines. The stator core of the analyzed permanent magnet synchronous motor (PMSM) is made of magnetic iron sheets. Three types PMSM stators are analyzed: laminated with open slots, laminated with closed slots using SMC, and SMC stators. The comparative analysis is based on the magnetic properties and the calculated parameters of each motor model. The studied electromagnetic and electromechanical parameters are flux densities in various sections of the magnetic circuit and electromagnetic torque. The parameters' values for the three types of stators are calculated using the finite element method (FEM).

Variable magnetic flux motor drive system

Abstract: A variable magnetic flux motor drive system includes: a permanent magnet motor (4); an inverter (1) for driving the permanent magnet motor; and magnetization means for applying a magnetization current for controlling the magnetic flux of the permanent magnet. The permanent magnet is a variable magnet having a magnetic flux density which can be changed by a magnetization current from the inverter (1). The magnetization means is a variable magnetic flux motor drive system characterized by applying a magnetization current above the magnetization saturation region of the magnetic substance of the variable magnet and improves the repetition accuracy of the magnetic flux of the variable magnet (53) and the torque accuracy.

A new PM machine topology for low-speed, high-torque drives

Abstract: The paper describes a completely new topology for a low-speed, high-torque permanent brushless magnet machine. Despite being naturally air-cooled, it has a significantly higher torque density than a liquid-cooled transverse-flux machine, whilst its power factor is similar to that of a conventional permanent magnet brushless machine. The high torque capability and low loss density are achieved by combining the actions of a speed reducing magnetic gear and a high speed PM brushless machine within a highly integrated magnetic circuit. In this way, the magnetic limit of the machine is reached before its thermal limit. The principle of operation of such a dasiapseudopsila direct-drive machine is described, and measured results from a prototype machine are presented.

Spin torque oscillator, magnetic recording head, magnetic head assembly, and magnetic recorder

Abstract: PROBLEM TO BE SOLVED: To provide a spin torque oscillator capable of stably oscillating with a low current density and also having a high intensity of an in-plane high frequency magnetic field, and to provide a magnetic recording head, a magnetic head assembly, and a magnetic recorder. SOLUTION: The spin torque oscillator is provided with: an amorphous soft magnetic layer; a non-magnetic layer having a close-packed crystal structure while being arranged on the amorphous soft magnetic layer; and a hard magnetic layer having the close-packed crystal structure and a perpendicular magnetic anisotropy while being arranged on the non-magnetic layer. COPYRIGHT: (C)2010,JPO&INPIT

Electromagnetic Foundations of Electrical Engineering

Abstract: PREFACE. To the Electrical Engineer Practitioner. To the Student. To the Instructor. ACKNOWLEDGEMENTS. PROJECT PORTFOLIO. Analysis of a power delivery system. Cylindrical type transmission lines. DC current transducer. Determination of the conductivity of a circular conducting disk. Directional coupler analysis. Ill-defined grounding problems. Induction machine analysis. Line matching technique using an exponential transmission-line section. Linear variable differential transformer. Magnetic actuator and sensor device. Overhead-line protection by ground-wires. Power line carrier communication. Pseudo-balanced three-phase lines. Screened high-voltage three-phase installation. Shielded three-phase cable analysis. Three-route microwave splitter. Transmission-line system with balun transformer for even to odd-mode conversion. Transmission-line system with transformer-stage matching. Two-way loudspeaker analysis. Variable reluctance transformer. PART I: A BRIEF OVERVIEW. INTRODUCTION. CHAPTER 1: BASIC FIELD VECTORS. 1.1: The Electric and Magnetic Field Vectors. 1.2: Constitutive Relations. 1.3: Units and Notation. 1.4: Fundamental Concepts of Voltage and Current Intensity. PART II: STATIONARY FIELD PHENOMENA. INTRODUCTION. CHAPTER 2: ELECTROSTATICS. 2.1 Fundamental Equations. 2.2 Gradient Electric Field, Electric Potential, Voltage, Kirchhoff's Voltage Law. 2.3 Electric Charge, Electric Displacement Vector. 2.4 Dielectric Media, Permittivity, Polarization, Dielectric Strength. 2.5 Conductors in Electrostatic Equilibrium. 2.6 Application Example (Filament of charge). 2.7 Capacitor, Capacitance, Electric Energy. 2.8 Application Example (Two-wire transmission line). 2.9 Multiple Conductor Systems. 2.10 Application Example (Electric coupling in printed circuit boards). 2.11 Electric Forces and Torques. 2.12 Homework Proposed Problems. CHAPTER 3: STATIONARY CURRENTS. 3.1 Fundamental Equations. 3.2 Conductivity, Current Density, Electric Circuits. 3.3 Current Intensity, Kirchhoff's Current Law. 3.4 Resistor, Conductance, Resistance, Ohm's Law. 3.5 Application Example (The potentiometer). 3.6 Application Example (The Wheatstone bridge). 3.7 Joule Losses, Generator Applied Field. 3.8 Generator Electromotive Force, Power Balance. 3.9 Homework Proposed Problems. CHAPTER 4: MAGNETIC FIELD OF STATIONARY CURRENTS. 4.1 Fundamental Equations. 4.2 Ampere's Law, Magnetomotive Force, Magnetic Voltage. 4.3 Magnetic Induction Field, Magnetic Induction Flux. 4.4 Application Example (Power line magnetic fields). 4.5 Magnetic Materials, Ferromagnetic Media, Saturation and Hysteresis. 4.6 Magnetic Circuits. 4.7 Application Example (Three-legged transformer). 4.8 Magnetic Reluctance. 4.9 Inductor, Inductance, Magnetic Flux Linkage, Magnetic Energy. 4.10 Application Example (Coaxial cable). 4.11 Hysteresis Losses. 4.12 Multiple Circuit Systems. 4.13 Magnetic Forces and Torques. 4.14 Application Example (U-shaped electromagnet). 4.15 Homework Proposed Problems. PART III: SLOW TIME-VARYING FIELDS. INTRODUCTION. CHAPTER 5: MAGNETIC INDUCTION PHENOMENA. 5.1 Fundamental Equations. 5.2 Gradient and Induction Electric Fields, Potential Vector. 5.3 Revisiting the Voltage Concept. 5.4 Induction Law. 5.5 Application Example (Magnetic noise effects). 5.6 Voltages and Currents in Magnetically Multicoupled Systems. 5.7 Application Example (Magnetic coupling in printed circuit boards). 5.8 Eddy Currents. 5.9 Generalization of the Induction Law to Moving Circuit Systems. 5.10 Application Example (Electromechanical energy conversion). 5.11 DC Voltage Generation. 5.12 AC Voltage Generation. 5.13 Homework Proposed Problems. CHAPTER 6: ELECTRIC INDUCTION PHENOMENA. 6.1 Fundamental Equations. 6.2 Displacement Current, Generalized Ampere's Law. 6.3 Charge Continuity Equation. 6.4 Revisiting the Current Intensity Concept. 6.5 Application Example (Capacitor self-discharge). 6.6 Voltages and Currents in Electrically Multicoupled Systems. 6.7 Homework Proposed Problems. CHAPTER 7: LUMPED PARAMETERS CIRCUIT ANALYSIS. 7.1 Introduction. 7.2 Steady-State Harmonic Regimes. 7.3 Transformer Analysis. 7.4 Transient Regimes. 7.5 Homework Proposed Problems. PART IV: RAPID TIME-VARYING FIELDS. INTRODUCTION. CHAPTER 8: ELECTROMAGNETIC FIELD PHENOMENA. 8.1 Electromagnetic Waves. 8.2 Poynting's Theorem, Poynting's Vector, Power Flow. 8.3 Time-Harmonic Fields, Field Polarization, RMS Field Values. 8.4 Phasor-Domain Maxwell Equations, Material Media Constitutive Relations. 8.5 Application Example (Uniform plane waves). 8.6 Complex Poynting's Vector. 8.7 Application Example (Skin effect). 8.8 Homework Proposed Problems. CHAPTER 9: TRANSMISSION LINE ANALYSIS. 9.1 Introduction. 9.2 Time-Domain Transmission-Line Equations for Lossless Lines. 9.3 Application Example (Parallel-plate transmission line). 9.4 Frequency-Domain Transmission-Line Equations for Lossy Lines. 9.5 Frequency-Domain Transmission-Line Equations for Lossless Lines. 9.6 Application Example (Line matching techniques). 9.7 Multiconductor Transmission Lines. 9.8 Application Example (Even and odd modes). 9.9 Homework Proposed Problems. APPENDICES. Appendix 1: Formulas from Vector Analysis. Appendix 2: Lorentz Transformation. Appendix 3: Elements of Complex Algebra. Appendix 4: Elements of Fourier Analysis. BIBLIOGRAPHY. INDEX.

Design of a Lightweight Transverse Flux Permanent Magnet Machine for Direct-Drive Wind Turbines

Abstract: The aim of this paper is to design a lightweight transverse flux permanent magnet (TFPM) machine for large scale direct-drive wind turbines. The requirements for suitable generator systems for wind turbines are discussed. Analytical modeling of TFPM machines is discussed by considering the machine parameters and the magnetic circuit. The proposed analytical model is verified by comparing it to results of finite element analysis and experiments. A new lightweight TFPM machine is designed for a 10 MW direct-drive wind turbine and it is compared to the RFPM machine.

Research on switched reluctance double-rotor motor used for hybrid electric vehicle

Abstract: In this paper, switched reluctance machine based double-rotor machine (SRDRM) is proposed. It is a kind of new structure electric machine with two electrical ports and two mechanical ports. Firstly, this paper presents the working principle of SRDRM, builds an equivalent magnetic-network model based on its magnetic structure, and establishes the theoretical analysis and computation fundamental. Secondly, a 2-D finite-element model (FEM) of SRDRM is built and the influence of the magnetic coupling between the outer motor and inner motor is analyzed.

Analysis and Optimization of Thrust Characteristics of Tubular Linear Electromagnetic Launcher for Space-Use

Abstract: Release-launch is a fundamental operation in space platform. Not like traditional land-base launcher, space-base launcher is more flexible and more efficient. Tubular linear electromagnetic launcher (TLEML), which provides higher force density, simple structure and no unilateral magnetic force, compared with the flat linear electromagnetic launcher, is more suitable for space platform. It can easily meet the demand such as little volume, light weight and high control precision. This paper analyzes and optimizes the thrust characteristics of tubular linear permanent magnet synchronous motors (TL-PMSM) for electromagnetic launcher, including different topologies, interior permanent magnet (IPM) and surface-mounted permanent magnet (SPM). First, build up the finite element model for the two kinds of TLEML and calculate the magnetic field. Then thrust force fluctuation figures are obtained by finite element analysis considering the pole/arc ratio, the pole pitch and the inner diameter/outer diameter ratio of the stator. The result shows that it can improve the thrust characteristic and decrease the cogging force by optimizing the parameters of the motor.

Twisted inductors for low coupling mixed-signal and RF applications

Abstract: Parasitic magnetic coupling is a major design challenge for integrated circuit designers. Fundamentally, it originates in conventional spiral inductors because the magnetic field is not localized, extending far beyond the perimeter. This paper introduces a twisted winding scheme for inductors that increases the localization of the magnetic field, reducing parasitic magnetic coupling by as much as 3100X and the edge-to-edge spacing of inductors by 10X. These results are validated in a 0.18 mum CMOS process.

Calculation of the shear force of highly coercive permanent magnets in magnetic systems with consideration of affiliation to a certain group based on residual induction

Abstract: The strength characteristics of various groups of permanent highly coercive magnets (made of alloys based on rare-earth elements), which are classified in groups with respect to residual induction and used in magnetic systems as rectangular prisms, are compared. The influence exerted on the specific interaction force of highly coercive permanent magnets by the gap between neighboring magnets side-by-side in a common magnetic circuit is demonstrated.

Time-Stepping Simulation of Synchronous Reluctance Motors Using a Nonlinear Reluctance Network Method

Abstract: We present a nonlinear reluctance network approach for the computation of the electromotive force (EMF) waveforms of synchronous reluctance motors (SynRM) with a massive rotor or a flux barrier rotor. We model all ferromagnetic parts of the machine by nonlinear reluctances in order to take the saturation into account. The model of the motor consists of three reluctance networks: of the stator, of the rotor, and of the air gap. The originality of the work lies in the automatic computation of the topology and of the reluctance values of the reluctance network. The computation models the air gap for any relative position of the rotor and the stator; thus, the movement of the rotor can be taken into account. For any saturation level, a comparison with time-stepping finite-element results shows good agreement for the EMF fundamental, the mean torque, and the EMF and torque harmonics of order lower than the slotting ones. For a normal saturation level, the reluctance network models also accurately compute the slotting harmonics.

Performance Improvement of a Rotary MR Fluid Actuator Based on Electromagnetic Design

Abstract: This study presents an electromagnetic design methodology for a rotary magnetorheological (MR) fluid actuator. In order to improve the performance of the MR fluid actuator, the magnetic field should be effectively applied to the MR fluid. Therefore, it is important that the magnetic circuit composed of the MR fluid, the ferromagnetic material for magnetic flux path, and the electromagnetic coil is well designed. For this purpose, two effective approaches are proposed: one is to shorten the magnetic flux path by removing the unnecessary bulk of the yoke in order to improve the static characteristic of the MR fluid actuator, and the other is to increase the magnetic reluctance of the magnetic circuit by minimizing the cross-sectional area of the yoke through which the magnetic flux passes in order to improve the dynamic and hysteretic characteristics. The effectiveness of the proposed design methodology is verified through magnetic analysis and a series of basic experiments.

Single-phase transformer model including magnetic hysteresis and eddy currents

Abstract: In this paper, a single-phase core-type and shell-type transformer model is proposed on the level of state equations. The magnetic hysteresis and the eddy currents effects are successfully included based on the analytical description of the magnetic core topology. Predicted values from simulations are in very good agreement with published measurements and hence, the developed transformer model is a powerful tool for transient and steady-state studies.

Determination of Parameters Considering Magnetic Nonlinearity in Solid Core Transverse Flux Linear Motor for Dynamic Simulation

Abstract: This paper presents methods to calculate motor parameters considering magnetic nonlinearity in solid core transverse flux linear motors (TFLM) for dynamic simulation. The magnetic field characteristics of the machine are analyzed by using 3-D equivalent magnetic circuit network (3-D EMCN) method, and parameters for dynamic simulation such as linkage flux, thrust, attraction force, and core loss are calculated by using the magnetic field analysis results. The calculated parameters are used as a form of lookup table in the dynamic simulation model. The accuracy of the method is examined by the comparison of input currents which are calculated by using the dynamic simulation model and measured for an example TFLM.

Design, fabrication and characterization of an externally actuated ON/OFF microvalve

Abstract: A magnetic microfluidic valve has been designed, fabricated and tested. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co–Ni (soft magnetic material) on a V-shaped cantilever beam. The deflection caused by the magnetic forces opens or closes the fluid flow. The microvalve performance has been optimized by means of finite element analysis (FEA). The FEA model has been experimentally validated using confocal microscopy and used to improve the magnetic circuit. Then, a fluidic cell has been built and the microvalve has been demonstrated to work as a check-valve or as ON/OFF valve when being magnetically actuated. Fabricated prototypes were evaluated in a flow of N2at the flow rate of 20 sccm. The operational applied pressure was 50 mbar. The microvalve has a leaking rate in the order of 1.75 sccm at 50 mbar.

Perturbation Finite Element Method for Magnetic Model Refinement of Air Gaps and Leakage Fluxes

Abstract: Model refinements of magnetic circuits are performed via a subproblem finite element method based on a perturbation technique. An approximate problem considering ideal flux tubes and simplified air-gap models is first solved. It gives the sources for a finite element perturbation problem considering the actual air gaps and flux tubes geometries with the exterior regions. The procedure simplifies both meshing and solving processes, and allows to quantify the gain given by each model refinement.

Modeling of Extra-high Voltage Magnetically Controlled Shunt Reactor

Abstract: From power system point of view, the multiple functions and application prospects of controllable shunt reactor in EHV and UHV power grid are analyzed;with 500kV magnetically controlled shunt reactor(MCSR) demonstration project in Jiangling converter station, China, the magnetic circuit structure and working principles of MCSR are analyzed, and the mathematic model of MCSR are deduced;on the basis of above, a new method of modeling complex magnetic circuit-magnetic circuit decomposition approach is proposed, and simulation model of MCSR is established.In order to verify the accuracy of the simulation model, the test results of 10 kV prototype and simulation results are compared, the experiments verify the accuracy of the simulation model.The proposed magnetic circuit decomposition approach is clear in principle, easy in modeling, precise in simulation result, applicable in engineering, suitable for power system electromagnetic transient calculation, and provides necessary simulation means for UHV and EHV MCSR analysis.