The paper discusses the problem of speed and flux estimation for the induction motor (IM) drive and presents a series of Sliding Mode Observers (SMOs) that are constructed using compound manifolds. Observers with compound manifolds have not been widely investigated because they cannot be designed following a standard procedure; however, it is shown that they have unique and useful properties. The paper introduces the candidate manifolds associated with IM estimation and shows various approaches for designing SMOs with compound manifolds. Generally, using the IM model, it is typical to design observers with simple manifolds. However, since the state transition matrix of the IM model depends on the motor speed, the problem is more complicated – the speed must either be known or it must be estimated. In the paper, several sensored and sensorless observer designs are presented. The paper presents the theoretical developments and shows simulations and experimental results.
Keywords: induction motor control, state estimation, speed estimation, slidingmode observers, sensorless control