Direct torque control of a six phase induction motor drive

Six-phase induction motor 'IM' has advantages over three phase'3-phi'IM like lower harmonics, lower losses, improved reliability, higher torque per ampere, and higher power rating drive. However the control of such motors is more complex than that of the 3-D*q motors. The principles of direct torque control 'DTC', which is a well-known control method for 3-D*q motors, can be utilized to overcome this complexity. Thispaper introduces the application of the DTC principles to 6-D*q IMs drives. The whole 6-D*q IM drive system is modeled and simulated in the stationary reference frame. However, it is noted from circuit analysis and Matlab simulations that the use of the conventional 6-D*q inverter gives poor performance drive. This is due to the fact that with the conventional inverter only six switching states can give balanced output voltages instead of 64 switching states. This results in lower capability of control, less utilization of the DC supply, and more harmonic distortion as well. However to avoid this demerits, the authors, after various trials, have inferred that the use of a dual 3-D*q inverter is the solution to be adapted. Simulation results of a DTC 6-q IM drive show improved performance over the results of the field orientation trials in the literature.