Hybrid speed controller for vector controlled cage induction motor drive

The conventional speed controllers for variable frequency fed cage induction motor suffer from the problem of stability, besides, these controllers show either steady state error (PD controller) or sluggish response (PI, PID) to the perturbation in reference setting or during load perturbation. On the other hand the fuzzy logic controller, introduces noise at the set point but it has very good transient performance. This paper presents a hybrid (a combination of fuzzy and PI) closed loop speed controller and its design for vector controlled induction motor drive (VCIMD). This controller has been implemented on a 3 phase, 415 V, 0.75 kW squirrel cage induction motor. Results are presented for the response of a vector controlled induction motor drive with a hybrid controller, combining the fuzzy logic and PI controller. The drive response obtained using hybrid controller are compared to the corresponding drive performance obtained using PI and fuzzy logic controller. Test responses of the developed variable speed drive along with simulated response are given and discussed in detail.