how to make parameters valid in components of ssc documentaion?

this code is from the SPICE cir after subcircuit2ssc,but it cannot ssc_build for the error :Invalid use of value 'node_2.v'. All entities referenced in this expression must be valid parameters.

• In mylibrary.rc1 (line 58)

the version I tried includes 2021a and 2023b

[yh shang]

this is my code:

component rc1

% rc1

% Component automatically generated from a SPICE netlist for subcircuit RC1.

% MATLAB version: 23.2.

% Simscape Electrical version: 23.2.

% Simscape code generated on: 07-Nov-2023 18:37:14

nodes

node_1 = foundation.electrical.electrical; % node_1

end

nodes(Access=protected, ExternalAccess=none)

node_2 = foundation.electrical.electrical;

end

annotations

UILayout = [

UIGroup('Parasitic elements', ...

specifyParasiticValues, capacitorSeriesResistance)

UIGroup('Smoothing functions', ...

specifySmoothValues, aWarning, expXh, expXl)

]

end

parameters

specifyParasiticValues = ee.enum.include.no; % Specify parasitic values

end

parameters(ExternalAccess=none)

capacitorSeriesResistance = {0, 'Ohm'}; % Capacitor parasitic series resistance

end

if specifyParasiticValues == ee.enum.include.yes

annotations

[capacitorSeriesResistance] : ExternalAccess=modify;

end

end

parameters

specifySmoothValues = ee.enum.include.no; % Specify function smooth parameters

end

parameters(ExternalAccess=none)

aWarning = ee.enum.include.no; % Include warning

expXh = {Inf, '1'}; % Upper boundary of linear extrapolation for exp(x), typical x=80

expXl = {-Inf, '1'}; % Lower boundary of linear extrapolation for exp(x), typical x=-80

end

if specifySmoothValues == ee.enum.include.yes

annotations

[aWarning, expXh, expXl] : ExternalAccess=modify;

end

end

components(ExternalAccess=observe)

R1 = foundation.electrical.elements.resistor(R={(1*1000),'Ohm'});

C_CGD1 = foundation.electrical.elements.capacitor(c={(0.5*simscape.function.expm(value(node_2.v,'V'), ...

expXl, expXh, aWarning)),'F'},r=capacitorSeriesResistance,g={0,'1/Ohm'},vc.priority=priority.none);

end

connections

connect(R1.p,node_1);

connect(R1.n,node_2);

connect(C_CGD1.p,node_2);

connect(C_CGD1.n,*);

end

end

Answer 1

[Pramil]

Hi Shang,

I am not a expert on SPICE but I can help you with the SSC code.

In the "components" attribute, you cannot use a variable whose value changes during simulation and since "node_2.v" changes during simulation, it results into an error.

Here is the updated code which works on MATLAB R2023b. Since the value of "C_CGD1" depends on "node_2.v", you can set it up in "equations" attribute.

component rc1
% rc1
% Component automatically generated from a SPICE netlist for subcircuit RC1.
% MATLAB version: 23.2.
% Simscape Electrical version: 23.2.
% Simscape code generated on: 07-Nov-2023 18:37:14
    nodes
        node_1 = foundation.electrical.electrical; % node_1
    end
        nodes(Access=protected, ExternalAccess=none)
        node_2 = foundation.electrical.electrical;
    end
    annotations
        UILayout = [
        UIGroup('Parasitic elements', ...
        specifyParasiticValues, capacitorSeriesResistance)
        UIGroup('Smoothing functions', ...
        specifySmoothValues, aWarning, expXh, expXl)
        ]
    end
    parameters
        specifyParasiticValues = ee.enum.include.no; % Specify parasitic values
    end
    parameters(ExternalAccess=none)
        capacitorSeriesResistance = {0, 'Ohm'}; % Capacitor parasitic series resistance
        C_CGD1 = {1,'F'};
    end
    if specifyParasiticValues == ee.enum.include.yes
        annotations
            [capacitorSeriesResistance] : ExternalAccess=modify;
        end
    end
    parameters
        specifySmoothValues = ee.enum.include.no; % Specify function smooth parameters
    end
    parameters(ExternalAccess=none)
        aWarning = ee.enum.include.no; % Include warning
        expXh = {Inf, '1'}; % Upper boundary of linear extrapolation for exp(x), typical x=80
        expXl = {-Inf, '1'}; % Lower boundary of linear extrapolation for exp(x), typical x=-80
    end
    if specifySmoothValues == ee.enum.include.yes
        annotations
            [aWarning, expXh, expXl] : ExternalAccess=modify;
        end
    end
    components(ExternalAccess=observe)
        R1 = foundation.electrical.elements.resistor(R={(1*1000),'Ohm'});
        C1 = foundation.electrical.elements.capacitor(c=C_CGD1,r=capacitorSeriesResistance,g={0,'1/Ohm'},vc.priority=priority.none);
    end
    equations
        C_CGD1 == {(0.5*simscape.function.expm(value(node_2.v,'V'), expXl, expXh, aWarning)),'F'};
        C1.c == C_CGD1;   
    end
    connections
    connect(R1.p,node_1);
    connect(R1.n,node_2);
    connect(C1.p,node_2);
    connect(C1.n,*);
    end
end

Hope it helps.