Vectorial Control of a Multiphase Induction Machine for Electronic Pole Commutation

This paper investigates the multiphase induction machine ability to changes its magnetic field polarity by modi-fying the supply sequence, i.e. supplying different stator Park plane. Because the first space harmonic representation for a given sequence is not sufficient to predict the torque/speed characteristic, a multi-harmonic model is needed. This model enables to simulate the machine transient and steady state, and accurately predict the final rotor speed for an open loop trial, especially when the final speed is not governed by the main space harmonic (i.e. differs from the expected synchronous speed). The model is then integrated in an indirect flux orientation control, and allows to simulate the machine behaviour for any sequences on closed loop. For an experimental 9- phases squirrel cage induction machine, the time step simulation results are compared with experimental tests, and show that the flux control allows the machine to run at any speed, on all sequences. Moreover, changing polarity changes the maximum current level for a given mechanical speed and torque, which is very important for inverter design.