B.L.J. Gysen

Modeling of Spherical Magnet Arrays Using the Magnetic Charge Model

This paper presents an analytical method for evaluating the magnetic flux density produced by spherical permanent magnet arrays used in spherical actuators. To investigate the performances of magnetic arrays, analytical models are used due to their lower computational time compared to 3-D finite element analysis. This paper presents an analytical model for the calculation of the magnetic field produced by a spherical permanent magnet array using magnetic charge modeling. To obtain the total magnetic field solution, first the magnetic field produced by a single spherical tile is considered. By means of superposition, the magnetic field produced by the array is obtained. Two magnet array topologies are modeled and the analytical results are validated using finite element analysis.

Series hybrid vehicle system analysis using an in-wheel motor design

Hybrid vehicles, which employ a technology combining gasoline and electric motors, are a hot item these days for transporters looking for ways to cut their fuel bills. To date, commercial systems implement diesel assisted electrical drives. As such the electrical motor is placed in a series or parallel configuration to assist the combustion engine. In the series configuration, the generator mounts directly to the engine, and most of the engine power is converted into electric energy to drive the traction motors at the axle/wheel ends. This enables the exclusion of the mechanical drive path between the engine and the drive wheels.

Topology Comparison of Slotless Permanent Magnet Semispherical Actuators

This paper presents a comparison of several three-degrees-of-freedom (DoFs) semispherical actuator topologies, which can mimic a shoulder joint of an actuated support system. A semianalytical model is applied to determine the torque performance as function of the position. Hence, the current distribution through the coils with minimized ohmic losses can be determined. The performed topology comparison is based on the average power dissipation and on a set of torque and range of motion requirements.

Multi-degree-of-freedom spherical permanent-magnet gravity compensator for mobile arm support systems

This paper presents a magnetic gravity compensator which is able to provide compensation around two axis of rotation for mobile arm support systems. Because of the compensation around two axes it provides more flexibility than the existing mechanical gravity compensators. This flexibility is achieved by using two semispherical permanent magnets, where the inner semisphere can rotate around the x, y and, z axis with respect to the outer semisphere. Several magnetization topologies, evaluated using 2D finite element analysis, are investigated and the most suitable topology is optimized in 2D finite element analysis. The optimization results are verified with 3D finite element analysis.

Efficiency of a regenerative direct-drive electromagnetic active suspension

The efficiency of a given direct-drive electromagnetic active suspension system for automotive applications is investigated. A McPherson suspension system is considered where the strut consists of a direct-drive brushless permanent magnet tubular actuator in parallel with a passive spring and damper. This suspension system has besides delivering active forces the possibility of regenerating power due to imposed movements. An LQR controller is developed for improvement of comfort and handling (dynamic tire load). Finally, the overall efficiency of the system is simulated for various road profiles.

Multi-degree-of-freedom spherical permanent magnet gravity compensator for mobile arm support systems

This paper presents a magnetic gravity compensator, which is able to provide compensation about two axes of rotation for mobile arm support systems. Because of the compensation about two axes, it provides more flexibility than the existing mechanical gravity compensators. This flexibility is achieved by using two semispherical permanent magnets, where the inner semisphere can rotate about the x-, y-, and z-axis with respect to the outer semisphere. Several magnetization topologies, which are evaluated using 2-D finite-element analysis (FEA), are investigated, and the most suitable topology is optimized in 2-D FEA. The optimization results are verified with 3-D FEA.

A fast semi-analytical model for the slotted structure of induction motors

Abstract- Afast,semi-analyticalmodelforinductionmotors(IMs)with36/28stator/rotorslotcombinationispresented.Incomparisontotraditionalanalyti-calmodelsforIMs,suchaslumpedparameter,magneticequivalentcircuitandanisotropiclayermodels,thepresentedmodelcalculatesacontinuousdistri-butionofthemagneticfluxdensityintheairgapandboththestatorandrotorslotsoftheIM.Duetoitssemi-analyticalnature,thecomputationtimeofthemodelisshortincomparisontoFiniteElementAnalysis(FEA)simulations.Also,itisshownthatthemodelresultsareingoodagreementwithlinearFEAsimulationresults.Thismakesthemodelverysuitablefordesigntools. Keyword- Harmonicmodeling,inductionmotor,semi-analytical,slotting 1 I NTRODUCTION Acrucialelementinthedesignofinductionmotors(IMs)istheavailabilityofasuitableelectromagneticmodeltopredicttheperformanceofthemotor. Typ-ical demandsforsucha modelare shortcomputa-tiontimes,highaccuracyandflexibilitywithrespecttoparametervariations. Historically,thelumpedpa-rametermodelisveryextensivelyusedforIManal-ysisanddesign[1,2]. Thismethodgenerallyhasashortcomputationtime, buttheaccuracyislimitedduetoitsdependenceonthemodelparametercalcu-lation. Manyeffectsareestimatedbycorrectionfac-tors,whichmeansthatthephysicaleffects,suchasleakageflux,arenotmodeledindetail. Ontheotherhand, a moreaccurateanddetailedanalysis ofIMperformanceisoftenobtainedusingFiniteElementAnalysis(FEA)[3].Thismethodcantakenon-linearsoft-magneticmaterialsandcomplexgeometriesintoaccount,butatthepriceofamuchlongercomputationtime. Also,parametervariationrequiresre-meshing,whichfurtherincreasescomputationtime.AlternativemethodsthathavebeeninvestigatedforIM analysis include Magnetic Equivalent Circuit(MEC)modeling[4,5]andAnisotropicLayerTheory(ALT)modeling[6,7].Boththesemethodscanhaverelativelyshortcomputationtimesandareabletotakeglobalsaturationeffectsintoaccount. However,forMEC modeling, themagneticfluxpathsshouldbeknowna-prioritoavoidverycomplexanddetailedmodelimplementations.Thisisnotpracticalforade-signtool.Furthermore,theALTmethodtakestheef-fectofthestatorandrotorslotsintoaccountglobally,butthelocalmagneticfluxdistributionisneglected.In this work, a semi-analytical model is presentedthat calculatesthestatic magneticfield distributionintheairgapandboththestatorandrotorslotsofanIM.Themodelisbasedontheharmonicmethoddescribedin[8]andimplementedforabenchmarkmotortopologyinpolarcoordinates. Theresultingmodelconsistsof33regionsand476systemequa-tions. Thetotalcomputationtimeforthismodelisintheorderoftenthsofasecond,includingthegen-erationoftheequationmatrix. ItisshownthattheresultsofthedevelopedmagneticfieldmodelareingoodagreementwithlinearFEAresults.Regardingthefuture,thedevelopedmodelpresentsthefirststeptowardsanadvancedsemi-analyticalde-signtoolforIMs. Althoughitisassumedthatthepermeabilityofthesoft-magneticmaterialisinfinite,theeffectsofsaturationcanbeaccountedforusingahybridcouplingtoasaturationmodel,e.g. basedonALTorMEC[9]. Furthermore,fixedcurrentdensi-tiesareappliedtothestatorandrotorslotsinordertovalidatethemagneticmodel.However,themagneticmodelcanbecoupledtostatorandrotorcircuitmod-elstoobtainasteady-stateoreventransientmodel.Fig.1.Halfofthebenchmarkmotorgeometry

Harmonic and magnetic charge model comparison of spherical permanent magnet structures considering a neumann boundary

The rapid advances in assistive devices brought out the desire of spherical actuators because of their multiple degrees of freedom and similarity to ball and socket joints [1]. For this application a high torque density is beneficial for the volume of these devices. Due to the typical structure of slotted spherical actuators, designs have to be modeled in 3-D to gain accurate results. As commercially available modeling tools, such as FEA (finite element analysis), are very time consuming, semi-analytical models are needed to optimize a design. A slotted topology can be evaluated by including a Neumann boundary, representing material with a high permeability and a surface current density sheet distribution to model the coils [2]. Two semi-analytical models exists for obtaining the magnetic flux density generated by a spherical permanent magnet array namely, harmonic model [3] and magnetic charge model [4].

Analysis and minimization of torque ripple for variable flux reluctance machines

Variable flux reluctance machines (VFRMs) are permanent-magnet-free three-phase machines and are promising candidates for applications requiring low cost and robustness. This paper studies the torque ripple and minimization methods for 12-stator VFRMs. Starting with the analysis of harmonics in the self and mutual inductances of field and armature windings, instantaneous torque equations are derived by virtual work method, which give a clear view on the dominated torque ripple components in VFRMs. Afterwards, the influences of motor topology on harmonics of the inductances as well as the torque ripple are investigated, such as number of rotor poles and tooth arc, etc. On the basis of the aforementioned analysis, harmonic injections in field current and armature current are analyzed for torque ripple reduction. The effectiveness of these two methods is investigated for non-saturated and saturated 12/10 VFRMs based on 2D finite element analysis. The results show good performance of torque ripple minimization by harmonic armature current injection.

Spectral element model for 2-D electrostatic fields in a linear synchronous motor

This paper presents a fast and accurate 2-D spectral element model for analyzing electric field distributions in linear synchronous motors. The electric field distribution is derived using the electric scalar potential for static cases. The spatial potential and electric field distributions obtained by the spectral element method are validated by finite element analysis. Protrusions, voids and rounded edges in the motor geometry are taken into account without loss of accuracy. Furthermore, the convergence and computational load of the spectral element model is investigated.