magnetic sim agreees with calculations now

4 files changed, 96 insertions, 56 deletions

diff --git a/coil_mag_materials.yml b/coil_mag_materials.yml
index 9efbb80..2f19103 100644
--- a/coil_mag_materials.yml
+++ b/coil_mag_materials.yml
@@ -9,31 +9,20 @@ ro4003c:
   Density: 1790  # 23°C
   Relative Permeability: 1
   Relative Permittivity: 3.55  
+fr4:
+  Density: 1850  # 23°C
+  Relative Permeability: 1
+  Relative Permittivity: 4.4
+  Heat Conductivity: 0.81  # in-plane
 ideal:
   Relative Permittivity: 1 
 copper:
   Density: 8960.0  # 0°C
-  Electric Conductivity: 32300000  # 200°C
+  Electric Conductivity: 59600000  # 20°C
   Emissivity: 0.012  # 327°C
   Heat Capacity: 415.0  # 200°C
   Heat Conductivity: 401.0  # 0°C
   Relative Permeability: 1
-  Relative Permittivity: 1
-graphite_CZ3-R6300:  # crucible
-  Density: 1730.0
-  Electric Conductivity: 58800
-  Emissivity: 0.81  # 205°C
-  Heat Capacity: 1237.0
-  Heat Conductivity: 65  # 20°C
-  Relative Permeability: 1
-  Relative Permittivity: 1
-graphite_FU8957:  # heater
-  Density: 1750.0
-  Emissivity: 0.81  # 250°C
-  Heat Capacity: 1237.0
-  Heat Conductivity: 105  # averaged over different given values
-  Relative Permeability: 1
-  Relative Permittivity: 1
 steel_1.4541:
   Density: 7900.0  # 20°C
   Electric Conductivity: 1370
@@ -42,26 +31,6 @@ steel_1.4541:
   Heat Conductivity: 15.0 # 20°C
   Relative Permeability: 1
   Relative Permittivity: 1
-tin_liquid:
-  Density: 6980.0
-  Electric Conductivity: 2080000
-  Emissivity: 0.064  # set equal to solid
-  Heat Capacity: 252.7
-  Heat Conductivity: 29.0
-  Relative Permeability: 1
-  Relative Permittivity: 1
-  Liquid: 'Logical True'
-tin_solid:
-  Density: 7179.0
-  Electric Conductivity: 4380000
-  Emissivity: 0.064
-  Heat Capacity: 244.0
-  Heat Conductivity: 60.0
-  Relative Permeability: 1
-  Relative Permittivity: 1
-  Solid: 'Logical True'
-  Melting Point: 505
-  Latent Heat: 59600
 water:
   Density: 1000.0
   Heat Capacity: 4182.0
diff --git a/coil_mag_solvers.yml b/coil_mag_solvers.yml
index bb7b169..496509c 100644
--- a/coil_mag_solvers.yml
+++ b/coil_mag_solvers.yml
@@ -1,16 +1,17 @@
 Static_Current_Conduction:
   Equation: Static Current Conduction
   Variable: Potential
+  Variable DOFs: 1
   Procedure: '"StatCurrentSolve" "StatCurrentSolver"'
   Calculate Volume Current: True
   Calculate Joule Heating: False
   Optimize Bandwidth: True
   Nonlinear System Max Iterations: 1
   Linear System Solver: Iterative
-  Linear System Iterative Method: BiCGStabl
+  Linear System Iterative Method: CG
   Linear System Max Iterations: 5000
   Linear System Convergence Tolerance: 1.0e-10
-  Linear System Preconditioning: ILU0
+  Linear System Preconditioning: ILU3
   Linear System ILUT Tolerance: 1.0e-3
   Linear System Abort Not Converged: False
   Linear System Residual Output: 20
@@ -21,6 +22,7 @@ Magneto_Dynamics:
   Procedure: '"MagnetoDynamics" "WhitneyAVSolver"'
   Newton-Raphson Iteration: True
   Nonlinear System Max Iterations: 1
+  Fix Input Current Density: True
   Linear System Solver: Iterative
   Linear System Preconditioning: none
   Linear System Convergence Tolerance: 1e-8
diff --git a/coil_parasitics.py b/coil_parasitics.py
index 47d5cd2..08a3603 100644
--- a/coil_parasitics.py
+++ b/coil_parasitics.py
@@ -1,15 +1,16 @@
 #!/usr/bin/env python3
 
+import math
 from pathlib import Path
 import multiprocessing
 import re
 import tempfile
-import subprocess
 import fnmatch
 import shutil
 import numpy as np
 
 from pyelmer import elmer
+import subprocess_tee
 import click
 from scipy import constants
 
@@ -31,6 +32,17 @@ def enumerate_mesh_bodies(msh_file):
             tag, _, name = line.partition(' ')
             yield name.strip().strip('"'), (int(dim), int(tag))
 
+# https://en.wikipedia.org/wiki/Metric_prefix
+SI_PREFIX = 'QRYZEPTGMk mµnpfazyrq'
+
+def format_si(value, unit='', fractional_digits=1):
+    mag = int(math.log10(abs(value))//3)
+    value /= 1000**mag
+    prefix = SI_PREFIX[SI_PREFIX.find(' ') - mag].strip()
+    value = f'{{:.{fractional_digits}f}}'.format(value)
+    return f'{value} {prefix}{unit}'
+
+
 INPUT_EXT_MAP = {
         '.grd': 1,
         '.mesh*': 2,
@@ -56,7 +68,7 @@ OUTPUT_EXT_MAP = {
         '.msh': 4,
         '.vtu': 5}
 
-def elmer_grid(infile, outfile=None, intype=None, outtype=None, cwd=None, **kwargs):
+def elmer_grid(infile, outfile=None, intype=None, outtype=None, cwd=None, stdout_log=None, stderr_log=None, **kwargs):
     infile = Path(infile)
     if outfile is not None:
         outfile = Path(outfile)
@@ -80,10 +92,20 @@ def elmer_grid(infile, outfile=None, intype=None, outtype=None, cwd=None, **kwar
             args.extend(str(v) for v in value)
         else:
             args.append(str(value))
-    subprocess.run(args, cwd=cwd, check=True)
 
-def elmer_solver(cwd):
-    subprocess.run(['ElmerSolver'], cwd=cwd)
+    result = subprocess_tee.run(args, cwd=cwd, check=True)
+    if stdout_log:
+        Path(stdout_log).write_text(result.stdout or '')
+    if stderr_log:
+        Path(stderr_log).write_text(result.stderr or '')
+
+def elmer_solver(cwd, stdout_log=None, stderr_log=None):
+    result = subprocess_tee.run(['ElmerSolver'], cwd=cwd, check=True)
+    if stdout_log:
+        Path(stdout_log).write_text(result.stdout or '')
+    if stderr_log:
+        Path(stderr_log).write_text(result.stderr or '')
+    return result
 
 
 @click.command()
@@ -132,14 +154,17 @@ def run_capacitance_simulation(mesh_file, sim_dir):
     boundary_airbox.data['Electric Infinity BC'] = 'True'
 
     with tempfile.TemporaryDirectory() as tmpdir:
-        if sim_dir:
-            tmpdir = str(sim_dir)
+        tmpdir = sim_dir if sim_dir else Path(tmpdir)
 
         sim.write_startinfo(tmpdir)
         sim.write_sif(tmpdir)
         # Convert mesh from gmsh to elemer formats. Also scale it from 1 unit = 1 mm to 1 unit = 1 m (SI units)
-        elmer_grid(mesh_file.absolute(), 'mesh', cwd=tmpdir, scale=[1e-3, 1e-3, 1e-3])
-        elmer_solver(tmpdir)
+        elmer_grid(mesh_file.absolute(), 'mesh', cwd=tmpdir, scale=[1e-3, 1e-3, 1e-3],
+                   stdout_log=(tmpdir / 'ElmerGrid_stdout.log'),
+                   stderr_log=(tmpdir / 'ElmerGrid_stderr.log'))
+        elmer_solver(tmpdir,
+                   stdout_log=(tmpdir / 'ElmerSolver_stdout.log'),
+                   stderr_log=(tmpdir / 'ElmerSolver_stderr.log'))
         
         capacitance_matrix = np.loadtxt(tmpdir / 'capacitance.txt')
 
@@ -194,6 +219,9 @@ def run_inductance_simulation(mesh_file, sim_dir):
     bdy_if_bottom.material = copper
     bdy_if_bottom.equation = copper_eqn
 
+    potential_force = elmer.BodyForce(sim, 'electric_potential', {'Electric Potential': 'Equals "Potential"'})
+    bdy_trace.body_force = potential_force
+
     # boundaries
     boundary_airbox = elmer.Boundary(sim, 'FarField', [physical['airbox_surface'][1]])
     boundary_airbox.data['Electric Infinity BC'] = 'True'
@@ -206,15 +234,46 @@ def run_inductance_simulation(mesh_file, sim_dir):
     boundary_vminus.data['Potential'] = 0.0
 
     with tempfile.TemporaryDirectory() as tmpdir:
-        if sim_dir:
-            tmpdir = str(sim_dir)
+        tmpdir = sim_dir if sim_dir else Path(tmpdir)
 
         sim.write_startinfo(tmpdir)
         sim.write_sif(tmpdir)
         # Convert mesh from gmsh to elemer formats. Also scale it from 1 unit = 1 mm to 1 unit = 1 m (SI units)
-        elmer_grid(mesh_file.absolute(), 'mesh', cwd=tmpdir, scale=[1e-3, 1e-3, 1e-3])
-        elmer_solver(tmpdir)
+        elmer_grid(mesh_file.absolute(), 'mesh', cwd=tmpdir, scale=[1e-3, 1e-3, 1e-3],
+                   stdout_log=(tmpdir / 'ElmerGrid_stdout.log'),
+                   stderr_log=(tmpdir / 'ElmerGrid_stderr.log'))
+        solver_stdout, solver_stderr = (tmpdir / 'ElmerSolver_stdout.log'), (tmpdir / 'ElmerSolver_stderr.log')
+        res = elmer_solver(tmpdir,
+                   stdout_log=solver_stdout,
+                   stderr_log=solver_stderr)
+        
+        P, R, U_mag = None, None, None
+        solver_error = False
+        for l in res.stdout.splitlines():
+            if (m := re.fullmatch(r'StatCurrentSolve:\s*Total Heating Power\s*:\s*([0-9.+-Ee]+)\s*', l)):
+                P = float(m.group(1))
+            elif (m := re.fullmatch(r'StatCurrentSolve:\s*Effective Resistance\s*:\s*([0-9.+-Ee]+)\s*', l)):
+                R = float(m.group(1))
+            elif (m := re.fullmatch(r'MagnetoDynamicsCalcFields:\s*ElectroMagnetic Field Energy\s*:\s*([0-9.+-Ee]+)\s*', l)):
+                U_mag = float(m.group(1))
+            elif re.fullmatch(r'IterSolve: Linear iteration did not converge to tolerance', l):
+                solver_error = True
+
+        if solver_error:
+            raise click.ClickException(f'Error: One of the solvers did not converge. See log files for details:\n{solver_stdout.absolute()}\n{solver_stderr.absolute()}')
+        elif P is None or R is None or U_mag is None:
+            raise click.ClickException(f'Error during solver execution. Electrical parameters could not be calculated. See log files for details:\n{solver_stdout.absolute()}\n{solver_stderr.absolute()}')
+
+        U = math.sqrt(P*R)
+        I = math.sqrt(P/R)
+        L = 2*U_mag / (I**2)
+
+        assert math.isclose(U, 1.0, abs_tol=1e-3)
+
+        print(f'Coil resistance calculated by solver: {format_si(R, "Ω")}')
+        print(f'Inductance calucated from field: {format_si(L, "H")}')
 
 
 if __name__ == '__main__':
     run_inductance_simulation()
+
diff --git a/twisted_coil_gen_twolayer.py b/twisted_coil_gen_twolayer.py
index 101042c..5f7e685 100644
--- a/twisted_coil_gen_twolayer.py
+++ b/twisted_coil_gen_twolayer.py
@@ -317,6 +317,8 @@ def traces_to_gmsh_mag(traces, mesh_out, bbox, model_name='gerbonara_board', log
     airbox_physical = gmsh.model.add_physical_group(3, [airbox], name='airbox')
     trace_physical = gmsh.model.add_physical_group(3, [toplevel_tag], name='trace')
 
+    gmsh.model.mesh.setSize([(0, tag) for dim, tag in gmsh.model.getBoundary([(3, toplevel_tag)], recursive=True) if dim == 0], 0.300)
+
     #interface_tags_top = gmsh.model.getBoundary([(3, contact_tag_top)], oriented=False)
     #interface_tags_bottom = gmsh.model.getBoundary([(3, contact_tag_bottom)], oriented=False)
 
@@ -464,6 +466,8 @@ def print_valid_twists(ctx, param, value):
 @click.option('--via-offset', type=float, default=None, help='Radially offset vias from trace endpoints [mm]')
 @click.option('--keepout-zone/--no-keepout-zone', default=True, help='Add a keepout are to the footprint (default: yes)')
 @click.option('--keepout-margin', type=float, default=5, help='Margin between outside of coil and keepout area (mm, default: 5)')
+@click.option('--copper-thickness', type=float, default=0.035, help='Copper thickness for resistance calculation and mesh generation in mm. Default: 0.035mm ^= 1 Oz')
+@click.option('--board-thickness', type=float, default=1.53, help='Board substrate thickness for mesh generation in mm. Default: 1.53mm')
 @click.option('--twists', type=int, default=1, help='Number of twists per revolution. Note that this number must be co-prime to the number of turns. Run with --show-twists to list valid values. (default: 1)')
 @click.option('--circle-segments', type=int, default=64, help='When not using arcs, the number of points to use for arc interpolation per 360 degrees.')
 @click.option('--show-twists', callback=print_valid_twists, expose_value=False, type=int, is_eager=True, help='Calculate and show valid --twists counts for the given number of turns. Takes the number of turns as a value.')
@@ -477,7 +481,8 @@ def print_valid_twists(ctx, param, value):
 @click.version_option()
 def generate(outfile, turns, outer_diameter, inner_diameter, via_diameter, via_drill, via_offset, trace_width, clearance,
              footprint_name, layer_pair, twists, clipboard, counter_clockwise, keepout_zone, keepout_margin,
-             arc_tolerance, pcb, mesh_out, magneticalc_out, circle_segments, mag_mesh_out):
+             arc_tolerance, pcb, mesh_out, magneticalc_out, circle_segments, mag_mesh_out, copper_thickness,
+             board_thickness):
     if 'WAYLAND_DISPLAY' in os.environ:
         copy, paste, cliputil = ['wl-copy'], ['wl-paste'], 'xclip'
     else:
@@ -722,7 +727,12 @@ def generate(outfile, turns, outer_diameter, inner_diameter, via_diameter, via_d
             svg_vias.append(Tag('circle', cx=xv, cy=yv, r=via_diameter/2, stroke='none', fill='white'))
             svg_vias.append(Tag('circle', cx=xv, cy=yv, r=via_drill/2, stroke='none', fill='black'))
 
-    print(f'Approximate track length: {clen*twists*2:.2f} mm', file=sys.stderr)
+    l_total = clen*twists*2
+    print(f'Approximate track length: {l_total:.2f} mm', file=sys.stderr)
+    A = copper_thickness/1e3 * trace_width/1e3
+    rho = 1.68e-8
+    R = l_total/1e3 * rho / A
+    print(f'Approximate resistance: {R:g} Ω', file=sys.stderr)
 
     top_pad = make_pad(1, [layer_pair[0]], outer_radius, 0)
     pads.append(top_pad)
@@ -812,10 +822,10 @@ def generate(outfile, turns, outer_diameter, inner_diameter, via_diameter, via_d
 
         r = outer_diameter/2 + 20
         if mesh_out:
-            traces_to_gmsh(traces, mesh_out, ((-r, -r), (r, r)))
+            traces_to_gmsh(traces, mesh_out, ((-r, -r), (r, r)), copper_thickness=copper_thickness, board_thickness=board_thickness)
 
         if mag_mesh_out:
-            traces_to_gmsh_mag(traces, mag_mesh_out, ((-r, -r), (r, r)))
+            traces_to_gmsh_mag(traces, mag_mesh_out, ((-r, -r), (r, r)), copper_thickness=copper_thickness, board_thickness=board_thickness)
 
         if magneticalc_out:
             traces_to_magneticalc(traces, magneticalc_out)