Quasi time-invariant parameter modeling and control of unbalanced induction machines

This paper proposes a time-invariant model to characterize the three-phase unbalanced ac machine. The primary three-phase model is transformed into a modified odq representation that takes into account the number of coil turns of each stator winding. When the three-phase stator voltage is known, the odq model can be considered as similar to that of an odq balanced model, except for a very small term depending of the machine resistance. The vector model is suitable for deriving control schemes for unbalanced operation and is also useful for computer simulation studies as will be presented in the paper. Simulation and experimental results are presented.