Vector control of dual stator winding induction machine: A new technique to neutralize effects of rotor time constant variations

A new vector control drive, built for a dual stator winding induction machine (DSIM), is presented in this paper. Such a machine consists of a standard squirrel-cage rotor and a stator with two separate similar windings. With two 3-phase independent stator currents, it is possible to separate functions: a stator winding is used for flux and the other for torque. This separation is natural for DC machine and inductor power is very low. It is similar for DSIM when vector control is perfect, the active power of flux winding is very low. Using complex space vector theory, this active power can be determined for any rotor flux orientation. Calculus shows that, from active power measurements, it is possible to compute the rotor flux space vector alignment default. This interesting piece of information is used as an actuating signal in an a additional control loop able to correct this default and keeps the independence of flux and torque.