High-torque-density control of multiphase induction motor drives operating over a wide speed range

—The high-order harmonics of the magnetic fieldcanbeusedinsometypologiesofmultiphasemachine to improve the torque density. However, maximizing the torque capability depends on the thermal, voltage, and current constraints of the machine and the inverter. In this paper, a rotor-flux-oriented control scheme, which is capable of exploiting the maximum torque at any speed, is presentedformultiphaseinductionmotordrives.Belowthe base speed, the torque improvement is obtained by adding athirdharmoniccomponenttothefundamentalcomponent of the air-gap magnetic field. At high speeds, the amplitude of the field harmonics is progressively reduced to ensure the widest possible operating speed range. The validity of the proposed control scheme is confirmed by experimental tests.