Design and analysis of a family of speed and state Sliding Mode observers with compound manifolds for the induction motor drive

The paper discusses the problem of speed and state estimation for the induction motor (IM) drive and presents the design of a family of Sliding Mode (SM) observers that are constructed using compound manifolds. Generally, given the stationary reference frame model of the IM, several methods can be used to estimate the speed and the states. In particular, if estimation is done with SM methods, it is typical to use simple manifolds (usually, the current mismatches). However, SM observers with compound manifolds have very interesting properties. The paper examines a specific observer that uses a discontinuous speed estimate; then, it attempts to design similar SM observers with alternative compound manifolds. Three observers are attempted and their convergence and estimation properties are investigated. The paper finds that the original observer offers the only viable design. The theory is supported by simulations.