231 lines
7.7 KiB
C++
231 lines
7.7 KiB
C++
/*
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* This program source code file is part of KICAD, a free EDA CAD application.
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*
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* Copyright (C) 1992-2021 Kicad Developers, see AUTHORS.txt for contributors.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 3
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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// See equation 9b in this paper:
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// https://adam-research.de/pdfs/TRM_WhitePaper10_AdiabaticWire.pdf
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// See equation 8
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//https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=Fusing+of+wires+by+electrical+current&btnG=
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#define ABS_ZERO ( -273.15 )
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#include <calculator_panels/panel_fusing_current.h>
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#include <pcb_calculator_settings.h>
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#include <string_utils.h>
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#include <widgets/unit_selector.h>
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#include <i18n_utility.h> // For _HKI definition
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wxString fusing_current_help =
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#include "fusing_current_help.h"
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PANEL_FUSING_CURRENT::PANEL_FUSING_CURRENT( wxWindow * parent, wxWindowID id,
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const wxPoint& pos, const wxSize& size,
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long style, const wxString& name ) :
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PANEL_FUSING_CURRENT_BASE( parent, id, pos, size, style, name )
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{
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// Set some defaults
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m_ambientValue->SetValue( wxString::Format( wxT( "%i" ), 25 ) );
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m_meltingValue->SetValue( wxString::Format( wxT( "%i" ), 1084 ) ); // Value for copper
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m_meltingValue->SetEditable( false ); // For now, this panel only works for copper.
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m_widthValue->SetValue( wxString::Format( wxT( "%f" ), 0.1 ) );
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m_thicknessValue->SetValue( wxString::Format( wxT( "%f" ), 0.035 ) );
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m_currentValue->SetValue( wxString::Format( wxT( "%f" ), 10.0 ) );
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m_timeValue->SetValue( wxString::Format( wxT( "%f" ), 0.01 ) );
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// show markdown formula explanation in lower help panel
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wxString msg;
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ConvertMarkdown2Html( fusing_current_help, msg );
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m_htmlHelp->SetPage( msg );
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// Needed on wxWidgets 3.0 to ensure sizers are correctly set
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GetSizer()->SetSizeHints( this );
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}
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PANEL_FUSING_CURRENT::~PANEL_FUSING_CURRENT()
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{
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}
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void PANEL_FUSING_CURRENT::ThemeChanged()
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{
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// Update the HTML window with the help text
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m_htmlHelp->ThemeChanged();
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}
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void PANEL_FUSING_CURRENT::m_onCalculateClick( wxCommandEvent& event )
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{
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double Tm, Ta, I, W, T, time;
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bool valid_Tm, valid_Ta, valid_I, valid_W, valid_T, valid_time;
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valid_Tm = m_meltingValue->GetValue().ToDouble( &Tm );
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valid_Ta = m_ambientValue->GetValue().ToDouble( &Ta );
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valid_I = m_currentValue->GetValue().ToDouble( &I );
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valid_W = m_widthValue->GetValue().ToDouble( &W );
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valid_T = m_thicknessValue->GetValue().ToDouble( &T );
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valid_time = m_timeValue->GetValue().ToDouble( &time );
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double scalingT, scalingW;
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scalingT = m_thicknessUnit->GetUnitScale();
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scalingW = m_widthUnit->GetUnitScale();
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T *= scalingT;
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W *= scalingW;
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valid_Tm &= std::isfinite( Tm );
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valid_Ta &= std::isfinite( Ta );
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valid_I &= std::isfinite( I );
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valid_W &= std::isfinite( W );
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valid_T &= std::isfinite( T );
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valid_time &= std::isfinite( time );
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if( valid_Tm && valid_Ta )
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{
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valid_Tm &= ( Tm > Ta );
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valid_Ta &= ( Tm > Ta ) && ( Ta > ABS_ZERO );
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}
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valid_I &= ( I > 0 );
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valid_W &= ( W > 0 );
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valid_T &= ( T > 0 );
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valid_time &= ( time > 0 );
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double A = W * T;
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// The energy required for copper to change phase ( fusion ) is 13.05 kJ / mol.
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// Copper molar mass is 0.06355 kg/mol
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// => The copper energy required for the phase change is 205.35 kJ / kg
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double latentHeat = 205350.0;
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// The change in enthalpy is deltaH = deltaU + delta P * deltaV
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// with U the internal energy, P the pressure and V the volume
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// But for constant pressure, the change in enthalpy is simply the thermal energy
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// Copper specific heat energy is 0.385 kJ / kg / K.
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// The change in heat energy is then 0.385 kJ / kg per degree.
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double cp = 385; // Heat capacity in J / kg / K
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double deltaEnthalpy = ( Tm - Ta ) * cp;
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double density = 8940; // Density of copper to kilogram per cubic meter;
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double volumicEnergy = density * ( deltaEnthalpy + latentHeat );
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// Equation (3) is equivalent to :
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// VolumicEnergy * Volume = R * I^2 * t
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// If we consider the resistivity of copper instead of its resistance:
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// VolumicEnergy * Volume = resistivity * length / Area * I^2 * t
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// For a unit length:
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// VolumicEnergy * Area = resistivity / Area * I^2 * t
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// We can rewrite it as:
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// VolumicEnergy * ( Area / I )^2 / resistivity = t
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// coeff * ( Area / I ) ^2 = t with coeff = VolumicEnergy / resistivity
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// Copper resistivity at 20C ( 293K ) is 1.72e-8 ohm m
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// Copper temperature coefficient is 0.00393 per degree
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double Ra = ( ( Ta - ABS_ZERO - 293 ) * 0.00393 + 1 ) * 1.72e-8;
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double Rm = ( ( Tm - ABS_ZERO - 293 ) * 0.00393 + 1 ) * 1.72e-8;
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// Let's consider the average resistivity
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double R = ( Rm + Ra ) / 2;
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double coeff = volumicEnergy / R;
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bool valid = valid_I && valid_W && valid_T && valid_Ta && valid_Tm && valid_time;
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if( m_widthRadio->GetValue() )
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{
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if( valid )
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{
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A = I / sqrt( coeff / time );
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W = A / T;
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m_widthValue->SetValue( wxString::Format( wxT( "%f" ), W / scalingW ) );
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}
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else
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{
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m_widthValue->SetValue( _( "Error" ) );
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}
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}
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else if( m_thicknessRadio->GetValue() )
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{
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if( valid )
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{
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A = I / sqrt( coeff / time );
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T = A / W;
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m_thicknessValue->SetValue( wxString::Format( wxT( "%f" ), T / scalingT ) );
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}
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else
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{
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m_thicknessValue->SetValue( _( "Error" ) );
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}
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}
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else if( m_currentRadio->GetValue() )
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{
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if( valid )
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{
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I = A * sqrt( coeff / time );
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m_currentValue->SetValue( wxString::Format( wxT( "%f" ), I ) );
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}
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else
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{
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m_currentValue->SetValue( _( "Error" ) );
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}
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}
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else if( m_timeRadio->GetValue() )
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{
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if( valid )
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{
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time = coeff * A * A / I / I;
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m_timeValue->SetValue( wxString::Format( wxT( "%f" ), time ) );
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}
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else
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{
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m_timeValue->SetValue( _( "Error" ) );
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}
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}
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else
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{
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// What happened ??? an extra radio button ?
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}
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// Now let's check the validity domain using the formula from the paper.
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// https://adam-research.de/pdfs/TRM_WhitePaper10_AdiabaticWire.pdf
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// We approximate the track with a circle having the same area.
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double r = sqrt( A / M_PI ); // radius in m;
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double epsilon = 5.67e-8; // Stefan-Boltzmann constant in W / ( m^2 K^4 )
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double sigma = 0.5; // Surface radiative emissivity ( no unit )
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// sigma is according to paper, between polished and oxidized
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double tmKelvin = Tm - ABS_ZERO;
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double frad = 0.5 * ( tmKelvin + 293 ) * ( tmKelvin + 293 ) * ( tmKelvin + 293 );
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double tau = cp * density * r / ( epsilon * sigma * frad * 2 );
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if( 2 * time < tau )
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{
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m_comment->SetLabel( "" );
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}
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else
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{
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m_comment->SetLabel( _( "Current calculation is underestimated due to long fusing time."
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) );
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}
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} |