Modelling and analysis of a nine-phase induction motor with third harmonic current injection

Using electric motors with a number of phases greater than three may present some advantages over conventional three phase machines in the following applications: high power levels, electric vehicles and applications that require high levels of reliability. Multiphase machines, meaning designs comprising more than three phases, also allows an increase in torque density from the injection of harmonic currents. It is shown in this paper a comprehensive approach for the derivation of equivalent circuits for steady state operation for both fundamental and third harmonic frequencies for a nine-phase motor with concentrated windings and full pitch. Besides that, simulation of the dynamic model of the machine is done to obtain the expected torque improvement.