.Modelica.Magnetic.QuasiStatic.FundamentalWave.Examples.BasicMachines.InductionMachines.IMC_Inverter

Information

An ideal frequency inverter is modeled by using a VfController and a three-phase SignalVoltage. Frequency is raised by a ramp, causing the induction machine with squirrel cage to start, and accelerate inertias. At time tStep a load step is applied.

Simulate for 1.5 seconds and plot (versus time):

• currentQuasiRMSSensor.I: stator current RMS
• aimc.wMechanical: machine speed
• aimc.tauElectrical: machine torque
• fs: stator frequency
• fr: rotor frequency
• s: slip

Compare with transient models IMC_Inverter (Electrical.Machines) and IMC_Inverter (FundamentalWave). Note that electrical transients are neglected, but mechanical transients are taken into account.

Theoretical thoughts

By setting the stator resistance Rs = 0, comparing quasistatic points of operation for different stator frequencies fs, it can be seen that

• in the base region fs ≤ fNominal rotor frequency fr is constant, if the load torque is constant,
• whereas in the field weakening region f ≥ fNominal slip is constant, if load torque is adapted according to tau = tauNominal*fNominal/f.

Default machine parameters are used.