Z-Type Observer Backstepping for Induction Machines

This paper contains a relatively new synthesis method for nonlinear objects, which is named backstepping. This method can be used to obtain the observer structure. This paper presents the structure of the speed observer, which is a new proposition of observer backstepping with additional state variables marked Z. The rotor speed can be estimated in three different ways. The first is based on the adaptive approach, the second on the nonadaptive approach, and the third on improvement of the adaptive approach. The stability of the Z-type observer is determined by the Lyapunov stability criteria. Despite this, stability analysis around the machine´s working point is undertaken. All the machine tests are prepared in the sensorless control system based on multiscalar variables. The experimental results show the effectiveness of the proposed solution. The squirrel-cage model parameter estimation is not presented in this paper.