Modelica libraries

• Modelica basics:
  • blocks define equations, not assignments
  • blocks have connectors where lines start/end to pass (several) variables (in and out)
  • connecting blocks creates additionally equations
  • the simulation environment collects all equations and solves them (somehow)
  • causality is implicit and dynamic
• Variable types at connector:
  • flow variables
    • add up to zero at a connection point
    • often are time derivatives of conserved quantities (like electric current or mass flow)
  • potential variables
    • have the same value at a connection point
    • can often be shifted by a global constant (like voltage or pressure)
  • input/output variables
    • are transported from output to inputs
    • work like Simulink signals
• Balanced model:
  • in connector: #(flow variables) = #(potential variables)
  • add input/output variables al gusto
  • only connect input with outputs (of course!)
  • in block: #(equations) = #(flow variables) + #(output variables)