ANSYS 7.1 TUTORIAL Magnetostatic problems Ruben Specogna A.A. 2005/06 Università di Udine Dipartimento DIEGM Gruppo di Elettrotecnica Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Magnetostatic problems Usually the formulation used is based on magnetic vector potential A: First example: Infinite rectangular massive conductor carrying uniform current density It has planar symmetry  2D b=h=10mm ET PLANE53 for second order element for 2D magnetostatic (both planar and axialsymmetric problems), see PLANE13 for 1st order element Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Preprocessing task File “Magnetostatica_2D_corr_imp_planare.txt” /PREP7 !start the preprocessing /TITLE,2D Planar Magnetostatic !defining title et,1,plane53 !defining element type (ET) et,2,plane53 !plane13 for first order. For axisymmetrical problem add: !keyopt,1,3,1 and keyopt,2,3,1 !syntax: KEYOPT,material_constant,kp_number,kp_value b=10e-3 !geometric parameter h=10e-3 !geometric parameter curr=1 !current Jsz=curr/(b*h) !corrensponding current density mp,murx,1,1 ! Permeability of air mp,murx,2,1 ! Permeability of the conductor Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Model & materials wpave,10*b/2,0 !setting a new working plane rectng,-b/2,b/2,-h/2,h/2 !conductor rectng,10*(-b/2),10*(b/2),10*(-h/2),10*(h/2) !air asel,all !selecting all areas aovlap,all !find intersections in the areas numcmp,all !number compression aplot !plotting areas !material properties !air asel,all aatt,1 !conductor asel,s,,,1 aatt,2 Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Mesh, source & b. cond.s !mesh generation alls,all smrtsize,1 !specify the refinement of the mesh mshape,1 !triangular mesh mshkey,0 !free meshing (not mapped mesh) amesh,all !mesh all areas !current source esel,s,mat,,2 !selecting area 2 (massive conductor) bfe,all,js,1,,,jsz !apply the source (body force element) !Syntax: BFE, ELEM, Label, STLOC, VALx, VALy, VALz, VALphase !boundary conditions lsel,s,ext !select all “external” lines automatically dl,all,,AZ,0,1 !force Az=0 on the nodes upon external lines !Defines DOF constraints on lines. !Syntax: DL, LINE, AREA, Label, Value1, Value2 Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Solution & postprocessing Finish /SOLU alls,all antype,static !magnetostatic solution solve The results can be seen with the GUI at: General Postprocessing  PlotResult  Contour Plot  2D Flux Lines or: General Postprocessing  PlotResult  Contour Plot  Element Solution and then select the variable to display: for ex. BSUM, JTSUM Then we can plot a vector field with: General Postprocessing  PlotResult  Vector Plot  Predefined and then choose for ex. B, H or JT (plf2d command) Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems EXAMPLE 2 We’ll consider an actuator. All materials are linear. We would like to calculate the force on the mobile armature. Due to axialsymmetry we will solve a 2D axialsymmetric problem. Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Preprocessing Example 2 /TITLE,2D Axisimmetrical Actuator ET,1,PLANE53 KEYOPT,1,3,1 !activating key option for axialsymmetry MP,MURX,1,1 !air MP,MURX,2,1000 !iron MP,MURX,3,1 !core (copper) MP,MURX,4,2000 !iron n=650 !some useful constants: number of turns i=1.0 !current ta=.75 !follows some geomtric constants tb=.75 tc=.50 td=.75 wc=1 hc=2 gap=.25 space=.25 ws=wc+2*space hs=hc+.75 w=ta+ws+tc hb=tb+hs h=hb+gap+td acoil=wc*hc !coil area jdens=n*i/acoil !coil current density Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems The geometry /PNUM,AREA,1 !with aplot will plot every area with different colors RECTNG,0,w,0,tb RECTNG,0,w,tb,hb RECTNG,ta,ta+ws,0,h RECTNG,ta+space,ta+space+wc,tb+space,tb+space+hc AOVLAP,ALL RECTNG,0,w,0,hb+gap RECTNG,0,w,0,h NUMCMP,AREA APLOT Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Materials !default air mat = 1 ASEL,S,AREA,,2 AATT,3 !core ASEL,S,AREA,,1 ASEL,A,AREA,,12,13,1 AATT,4 !upper iron ASEL,S,AREA,,3,5,1 ASEL,A,AREA,,7,8,1 AATT,2 !lower iron /PNUM,MAT,1 !(*) ALLSEL,ALL APLOT !(*) with aplot will plot every material with ! different colors (like the figure) Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Mesh and force computation SMRTSIZE,3 !setting the refinement of the mesh AMESH,ALL !mesh all the areas ESEL,S,MAT,,4 !select elements of material 4 CM,ARM,ELEM !with this collection of elements creates the !component named “ARM” FMAGBC,'ARM‘ !tells ANSYS that after solution I want to know !the resulting force on the component ARM ALLSEL,ALL ARSCAL,ALL,,,.01,.01,1,,,1 !scaling lengths in meters FINISH !finish the preprocessing Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Bound. cond.s & solution ESEL,S,MAT,,3 !selecting the coil material areas BFE,ALL,JS,1,,,jdens/.01**2 !imposing the source ESEL,ALL NSEL,EXT !select automatically all boundary nodes D,ALL,AZ,0 !impose A=0 on this nodes ALLSEL,ALL FINISH !finish the preprocessing /SOLU MAGSOLV !solve for magnetostatic SAVE FINISH Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Postprocessing !starting postoprocessing task /POST1 !plot 2D flux lines PLF2D !calculate the force on the ARM FMAGSUM !plot vector field B PLVECT,B,,,,VECT,ELEM,ON !plot |B| as a scalar field PLNSOL,B,SUM Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems EXAMPLE 3 3D actuator problem. Saturable materials: the solution is non-linear. (3 materials: air, core (saturable), armature (saturable). The coil is not meshed) Due to symmetry we model only ¼ of the domain. Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Preprocessing task /prep7 /title,3D Actuator n=500 !turns of the coil i=6 !current per turn et,1,96 !element type solid96 mp,murx,1,1 !assign mur=1 at air !activate a table for non-linear materials tb,bh,2,,40 !B-H table tbpt,,355,.7 !define all the points !of the B-H curve ,,405,.8 ,,470,.9 ,,555,1.0 ,,673,1.1 …for all the points… tbcopy,bh,2,3 !copies the table !from material 2 to material 3 Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Geometry /pnum,volu !plot the volume’s numbers block,0,63.5,0,25/2,0,25 /view,1,1,1,1 !change the angle of view (see syntax) /replot !replot block,38.5,63.5,0,25/2,25,125 block,13.5,63.5,0,25/2,125,150 vglue,all block,0,12.5,0,5,26.5,125 block,0,13,0,5.5,26,125.5 vovlap,1,2 numcmp,volu cyl4,,,0,0,100,90,175 vovlap,all Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Material and meshing vsel,s,,,1 !setting up materials vatt,3 vsel,s,,,3,5 vatt,2 allsel,all smrt,8 mshape,1,3d !tetrahedral mesh mshkey,0 !free mesh vmesh,all !mesh all volumes /pnum,mat,1 !plot different materials with different colors /number,1 !no numbers eplot !plot elements Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Source esel,s,mat,,3 cm,arm,elem !create the component “arm” fmagbc,'arm‘ !will calculate force on “arm” allsel,all vlscale,all,,,.001,.001,.001,,0,1 !scaling in meters local,12,0,0,0,75/1000 !change system of coordinates wpcsys,-1 !define a wp based on the system of coord. !define a racetrack coil race,.0285,.0285,.014,n*i,.018,.0966,,,'coil1' /eshape,1 !display the coil (it's NOT meshed) eplot save !save the database finish Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems

Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems Bound. con.s & Solution d,2,mag,0 allsel,all /solu magsolv,3,,,,,1 finish /post1 fmagsum,'arm' save *dim,cur,array,1 cur(1)=i lmatrix,1,'coil','cur' Specogna Ruben – ANSYS Tutorial Lecture 3 – Magnetostatic Problems