Reduction in Number of Switching Elements of the Inverter Unit for the Proposed Dual Stator Winding Squirrel-Cage Induction Motor Speed Control Drive

A dual stator winding induction motor (DSWIM) is a brushless squirrel-cage induction motor that contains a stator with two isolated three-phase windings wound with dissimilar number of poles. Generally, each stator winding is fed by an independent three-phase inverter. A direct vector control is a suitable method for controlling the DSWIM drive. In the vector control method, the estimation of the rotor flux is difficult at low speeds. In this paper, a direct vector control is proposed based on the rotor flux compensation. The achievement of this proposed control method is to maintain the standard performance of the motor drive at low speeds to reduce the power loss of the inverter unit compared to the conventional methods. In the proposed control method, the rotor flux is compensated with a PI controller. The proposed control scheme is based on the independent control of the rotor flux and the electromagnetic torque in the direct and orthogonal axises (d and q-axis), respectively. The rotor flux is compensated via reformed of the reference rotor flux. Also in this paper, for the first time, the reduction in number of switching elements of the inverter unit for the DSWIM drive can be achieved by utilizing five-leg and nine-switch power electronic converters. The advantages of using these proposed structures in the DSWIM drive are the reduction of the capital cost and also the reduction of power loss in the inverter unit.