Abstract
The rotor flux oriented control theory of induction motors has been presented for more than thirty years and there are also related commercial products available in the market. Its main characteristic lies in the instantaneous torque response to achieve as fast dynamic response as a separately excited dc motor drive. However, temperature variety will cause motor parameters drift and degrade the performance. It is hoped that this can be improved by replacing the parameters of flux linkage with constants. In spite of the fast torque response, maximization of the resulting torque is still a subject for further improvement. In fact, it is the main motivation of this thesis to propose a generalized flux oriented maximum torque control strategy for the induction motor drives. Major contributions of this thesis may be summarized as follows. First, a generalized flux oriented control model is derived in chapter 2 and the model can overcome the effect of motor parameters drifting. Second, analytic expressions of the corresponding slip angular frequency and the maximum torque are also derived. Based on the previous results, a generalized flux oriented maximum torque control strategy is then presented to further increase the dynamic response speed. Third, a soft and safe starting control strategy is presented to build up the initial rotor flux to achieve very fast starting response without violating the current and voltage constraints of the inverter. Finally, a prototype is also constructed to implement the proposed generalized flux oriented maximum torque control strategy by using a digital signal processor, namely TMS320F2812. Both simulation and experimental results verify the validity of the proposed control strategy.