Application of adaptive fuzzy control to ac machines

The decoupled control of torque and flux has made field-oriented control an attractive choice for high performance induction motor drives. However, changes in the speed tracking trajectory and external disturbances make it difficult to achieve an acceptable closed-loop tracking performance, especially when traditional linear controllers are used. This paper addresses this issue by applying direct and indirect adaptive fuzzy controllers for performance enhancement of variable speed control of induction machines. Theoretical background of these schemes is outlined, and then a simulation test bench has been established for performance evaluation under a variety of operating conditions. Such conditions include changes in the speed reference trajectory and presence of external disturbances, such as load changes. A comparison has been made among direct adaptive, indirect adaptive and direct fuzzy controllers to show the potential of applying adaptive fuzzy control techniques to induction machines.