This example investigates a time transient polyphase induction machine.
An ideal frequency inverter is modeled by using a simple 
voltage frequency controller 
and a polyphase voltage source with signal input.
Frequency is raised by a ramp up to nominal frequency, causing the induction machine with squirrel cage to start,
and accelerating inertias. At time tStep a load step is applied.
fActual: actual supply frequencyvoltageRMSSensor.V: quasi RMS stator voltageimc.stator.abs_Phi: magnitude of stator fluximc.tauElectrical: electromagnetic torqueimc.wMechanical: speedcurrentRMSSensor.I: quasi RMS stator current