Tuning of PI speed controller

PID controllers are very common in industrial systems applications. The tuning of these controllers is governed by system nonlinearities and continuous parameter variations. In this paper, a complete and rigorous comparison is made between two tuning algorithms. The PI controller was used in a speed control loop in a Direct Torque Control (DTC) scheme applied on an induction motor. The first method applies off-line genetic algorithm (GA) strategies and the other one makes use of an online Fuzzy Logic (FL) tuning scheme. DTC is then tested with the two schemes for two cases, with normal operating conditions and with a sudden change in load torque applied to the motor. Results obtained show that the fuzzy logic on-line tuning technique can provide better speed control performance when system parameter variations occur. On the other hand for nominal operation the genetic algorithms scheme is preferred. Index Terms – Speed control, induction motor, direct torque control, Fuzzy logic, Genetic algorithms.