No-Flow Component — Voltage Sensor

The following file, voltage_sensor.ssc, implements a component called voltage_sensor. An ideal voltage sensor has a very large resistance, so there is no current flow through the sensor. Therefore, declaring a Through variable, as well as writing branches and equation statements for it, is unnecessary.

The declaration section of the component contains:

  • Two electrical nodes, p and n (for + and – terminals, respectively)

  • An Across variable, voltage v1, to be connected to the electrical domain later in the file

Note that a Through variable (current ) is not declared, and there is no branches section.

In the equation section, the first equation, v == p.v - n.v, establishes the relationship between the component Across variable, voltage v1, and the component nodes (and therefore the domain Across variable at these nodes). It defines the voltage across the sensor as the difference between the node voltages.

The second equation defines the voltage sensor action:

  • V == v1, that is, output voltage equals the voltage across the sensor nodes

component voltage_sensor
% Voltage Sensor
% The block represents an ideal voltage sensor. There is no current
% flowing through the component, therefore it is unnecessary to
% declare a Through variable (i1), use a branches section, or
% create an equation statement for current (such as i1 == 0).
%
% Connection V is a physical signal port that outputs voltage value.


  outputs
    V = { 0.0, 'V' }; % V:bottom
  end

  nodes
    p = foundation.electrical.electrical; % +:top
    n = foundation.electrical.electrical; % -:bottom
  end

  variables
    v1 = { 0, 'V' };
  end

  equations
    v1 == p.v - n.v;
    V == v1;
  end

end