Dual stator winding induction machine drive

A new dual stator winding induction machine drive is described in this pape r. The proposed induction machine consists of a standard squirrel-cage roto r and a stator with two separate windings wound for a dissimilar number of poles. Each stator winding is fed from an independent variable-frequency va riable-voltage inverter, The proposed drive offers such advantages as speed sensorless operation, better reliability, and more flexibility to manipula te the resultant torque-speed curve of the motor. In the proposed drive, ze ro-speed operation is achieved by independently controlling the two sets of stator currents, hence, maintaining a minimum electrical frequency indepen dent of the mechanical speed. This feature is especially important to minim ize the negative impact of the stator resistance influence at low-speed ope ration and it greatly simplifies the implementation of speed sensorless con trol schemes. The drive is well suited for either constant volts per hertz or held-oriented (FO) operation. Circulating harmonic currents, common to m ost dual stator machines, are eliminated by the dissimilar pole number in e ach stator winding.