Документация

component CondResistor
% Linear Resistor with Optional Thermal Port
% If "Model thermal effects" is set to "Off", the block represents a
% linear resistor. The voltage-current (V-I) relationship is V=I*R,
% where R is the constant resistance in ohms.
%
% If "Model thermal effects" is set to "On", the block represents a
% resistor with a thermal port. The resistance at temperature T1 is given by
% R(T) = R0*(1+alpha(T1-T0)), where R0 is the Nominal resistance at the
% Reference temperature T0, and alpha is the Temperature coefficient.

nodes
    p = foundation.electrical.electrical; % +:left
    n = foundation.electrical.electrical; % -:right
    H = foundation.thermal.thermal;       % H:left
end

parameters
    thermal_effects = simscape.enum.onoff.off; % Model thermal effects
end

parameters(ExternalAccess=none)
    R = { 1, 'Ohm' };         % Nominal resistance
    T0 = {300,'K'};           % Reference temperature
    alpha = {50e-6,'1/K'};    % Temperature coefficient
    tc = {10,'s'};            % Thermal time constant
    K_d = {1e-3,'W/K'};       % Dissipation factor
end

variables(ExternalAccess=none)
    i = { 0, 'A' };                                         % Current
    v = { 0, 'V' };                                         % Voltage
    T1 = {value = {300,'K'}, priority = priority.high};  % Temperature
end

branches
    i : p.i -> n.i;
end

equations
    v == p.v - n.v;
end

if thermal_effects == simscape.enum.onoff.off
    annotations
        % Show non-thermal settings
        Icon = 'custom_resistor.png';
        [R, i, v] : ExternalAccess=modify;
        % Hide thermal node
        H : ExternalAccess=none;
    end
    connections
        connect(H, *); % Connect hidden thermal node to reference
    end
    equations
        R*i == v;
        T1 == T0;    % Temperature is constant
    end

else
    annotations
        % Show thermal settings
        Icon = 'custom_resistor_thermal.png';
        [T1, T0, alpha, tc, K_d, H] : ExternalAccess=modify;
    end

    % Add heat flow + thermal equations
    variables(Access=private)
        Q = { 0, 'J/s' }; % Heat flow
    end
    branches
        Q : H.Q -> *
    end
    equations
        T1 == H.T;
        let
            mc = tc*K_d; % mc in Q = m*c*dT
            % Calculate R(T), protecting against negative values
            Rdem = R*(1+alpha*(T1-T0));
            R_T = if Rdem > 0, Rdem else {0,'Ohm'} end;
        in
            R_T*i == v; % Electrical equation
            mc * T1.der == Q + R_T*i*i; % Thermal equation
        end
    end

end
end