Analysis and design of current controllers in vector controlled induction motor using complex signal flow graphs

The design of current controller in field coordinates has followed a simplified approach of assuming a first order system. How close is this approximation. The complex dynamic structure proposed recently forces us to relook the current control design strategies for induction motor drives. The position of complex poles is the consequence of the relative motion of the two AC windings. Hence conventional interpretations of system theory where jomega; terms are treated as damped oscillation frequency related to a certain eigen frequency cannot be applied. What should then be the criteria for pole positioning in such case? Moreover what are the implications for the PI control? This paper seeks to answer these questions. Both classical and the modern control strategies will be reviewed and their design procedure discussed.