Analytical solution for a separate state and parameter SDRE observer for a CSI-fed induction motor

A two-stage observer, for separate state and parameter estimation, based on the state dependent Riccati equation (SDRE) filter methodology, is applied to the third-order model of an induction machine which includes both electrical and mechanical dynamics (under the assumptions of linear magnetic circuits). The motor parameters are assumed to be known and constant, while the load torque is assumed unknown. Within the methodology, different parametrizations are introduced and compared. Finally, the relationship between the two-stage observer and its single stage progenitor is discussed.