Induction Machine Control in Presence of Magnetic hysteresis Modelling and Speed reference tracking

Abstract

The problem of controlling induction machine speed has generally been dealt with using standard models i.e. those based on the assumption that the magnetic characteristic is linear. In coherence with this assumption, most control strategies involved rotor flux regulation around a fixed nominal value. As a matter of fact, optimal performance operation (e.g. maximal efficiency, maximal torque, unitary power factor…) are not achievable using constant flux reference especially when facing wide range load variations. But, control strategies involving wide range flux reference variations can not be obtained without accounting for the nonlinearity of the machine magnetic characteristic. In the present work, we propose a new speed control strategy based on a new machine model that accounts for the magnetic characteristic hysteresis and saturation. A speed controller is designed using a nonlinear design technique. The performances of the proposed control strategy are formally analysed and their supremacy with respect to the standard control solution is illustrated through a simulation study, using a 7.5 KW machine