134 lines
3.5 KiB
Mathematica
134 lines
3.5 KiB
Mathematica
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%load all the FEMM functions. the folder with all the M files for FEMM should have already been added to path
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addpath('c:\\femm42\\mfiles');
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openfemm;
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function make_round_turn(x, y, radius, material, circuit)
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x1 = x - radius;
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x2 = x + radius;
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y1 = y;
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y2 = y;
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mi_drawarc(x1, y1, x2, y2, 180, 10);
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mi_addarc(x2, y2, x1, y1, 180, 10);
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mi_addblocklabel(x,y);
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mi_selectlabel(x,y);
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%comment out first for automeshing
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mi_setblockprop(material, 1, 0, circuit, 0, 0, 1);
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%mi_setblockprop(material, 0, 10E-3, circuit, 0, 0, 1);
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mi_clearselected;
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endfunction
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function make_rectangle(x, y, w, h, material, circuit)
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x1 = x - w/2;
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y1 = y - h/2;
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x2 = x + w/2;
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y2 = y - h/2;
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x3 = x + w/2;
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y3 = y + h/2;
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x4 = x - w/2;
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y4 = y + h/2;
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mi_drawpolygon([x1,y1;x2,y2;x3,y3;x4,y4])
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mi_addblocklabel(x,y);
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mi_selectlabel(x,y);
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%comment out first for automeshing
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mi_setblockprop(material, 1, 0, circuit, 0, 0, 1);
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%mi_setblockprop(material, 0, 10E-3, circuit, 0, 0, 1);
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mi_clearselected;
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endfunction
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% materials
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copper_conductivity = 58.0;
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%parameters. All dimentions in mm
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w_trace = 1; % width trace
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h_trace = 0.035; %thickness of 1oz copper
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h_pcb = 1.6; % 0.2mm prepreg
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freq = 0;
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probe_offset = 0.05; % distance from probe tip to wire
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%constants
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i_wire = 1;
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%sensor_offset = 1.6; %offset of from sensor to end of probe tip
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sensor_offset = 0.5;
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probe_sensitivity_H = 0.8; %volts/gauss
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probe_sensitivity_L = 0.2;
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probe_max_G = 6.0; % max field strength for sensor saturation
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trace_widths = [0.05 : 0.05 : 3]
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field_strengths = []
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for w_trace = trace_widths
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%create new document
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% "0 for a magnetics problem, 1 for an electrostatics problem, 2 for a heat flow problem, or 3 for a current flow problem"
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newdocument(0);
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% Define the problem type. Magnetostatic; Units of mm; Axisymmetric;
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% Precision of 10^(-8) for the linear solver; a placeholder of 0 for
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% the depth dimension, and an angle constraint of 30 degrees
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%(freq,units,type,precision,depth,minangle,(acsolver))
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mi_probdef(freq, 'millimeters', 'planar', 1.e-8, 100, 30);
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%define materials and circuits
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mi_addmaterial('Air', 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0);
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mi_addmaterial('Copper', 1, 1, 0, 0, copper_conductivity, 0, 0, 1, 0, 0, 0);
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mi_addcircprop('iwire', i_wire, 1);
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mi_addcircprop('iwireN', -1*i_wire, 1);
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%air
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mi_addblocklabel(0, -2);
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mi_selectlabel(0,-2);
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% (’blockname’, automesh, meshsize, ’incircuit’, magdir, group, turns)
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mi_setblockprop('Air', 1, 0, '<None>', 0, 0, 0);
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mi_clearselected
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% top trace
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make_rectangle(0, h_pcb/2 + h_trace/2, w_trace, h_trace, 'Copper', 'iwire');
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% return path
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make_rectangle(0, -h_pcb/2- h_trace/2, max(w_trace * 20, 20 * h_pcb), h_trace, 'Copper', 'iwireN');
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%boundary condition
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mi_makeABC(5, max(w_trace * 20, 50), 0,0, 0);
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mi_saveas('trace.fem');
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% mesh
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smartmesh(1);
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mi_createmesh();
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%run simulation
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mi_analyze();
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mi_loadsolution();
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%obtain B field
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measuredB = abs(mo_getb(0,(h_pcb/2 + probe_offset + sensor_offset))(1));
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measuredG = measuredB ./ 1E-4; % convert tesla to gauss
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current_sensitivity_H = measuredG * probe_sensitivity_H;
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current_sensitivity_L = measuredG * probe_sensitivity_L;
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probe_max_current = probe_max_G ./ measuredG;
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disp("Field Strength:");
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disp(measuredG);
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disp("Sensitivity High Gain:");
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disp(current_sensitivity_H);
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disp("Sensitivity Low Gain:");
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disp(current_sensitivity_L);
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disp("Max Current:");
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disp(probe_max_current);
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field_strengths = [field_strengths measuredG]
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mi_close();
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endfor
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export_data = [trace_widths;field_strengths]'; % '
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csvwrite("trace_fields.csv", export_data )
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