Theoretical and experimental comparison of indirect field-oriented controllers for induction motors

A theoretical and experimental comparison between standard and recently-developed improved indirect field-oriented controllers for induction motors is presented. It is shown that standard indirect field-oriented control algorithm provides asymptotic speed and flux regulation, while the improved one guarantees global exponential speed-flux tracking under condition of constant load torque. The difference between the flux sub-system design for the two controllers is analyzed. It is shown that the improved controller provides closed loop properties for flux subsystem when motor is rotating, leading to robust stabilization of the rotor flux vector space position and robust tracking of its modulus. It is demonstrated that both controllers have similar complexity and can be tuned using standard procedure for cascaded systems. Intensive experimental study shows that improved controller provides about one order higher speed tracking performance as compared with standard solution. Moreover, improved robustness with respect to rotor parameters variation leads to improved energy efficiency and robust stabilization of dynamic performance.