High gain observer for sensorless induction motor

Abstract

The synthesis of a high gain observer for the on-line estimation of the rotor fluxes, the motor speed and the load torque of the induction motor from the current and voltage measurements is presented. The synthesis of the observer is preceded by an observability analysis of the induction motor leading thereby to a sufficient condition. The obtained condition is discussed and it is shown that it is generally satisfied in practice when considering the usual operating conditions of the motor. Of particular interest, an implementation procedure is proposed to deal with the observation singularities. The proposed observer has been validated in simulation using the reference trajectories of a realistic proposed benchmark where the induction motor model remains in an unobservable region and not just go across.

High gain adaptive observer design for sensorless state and parameter estimation of induction motors

“…This condition is similar to that given in [9] and it has shown in [26] that is possible to express (14) in function of the rotor flux angle and the load torque using the expressions of 2…”

“…According to its triangular structure, the full rank condition of the matrix L Ψ follows from the full rank condition of its submatrix L 2 (See [26] for further details).…”

“…The adaptive observer design will be carried out following the approach proposed in [24] and [25] together with the implementation procedure proposed in [26]. We will first focus on the adaptive observer design on the basis of the triangular form before coming back to the original coordinates.…”

“…The observability analysis will be carried out in two steps following the approach proposed in [26]. The first step consists in seeking a state transformation Ψ: x ∈ 1 ( , , ) ( , ) ,…”

“…The second contribution provides an adaptive observer that has been recently proposed in [25] under an admissible persistent excitation assumption thanks to a genuine exploitation of the characteristic indices associated to the unknown parameters. The third contribution has been proposed in [26] to addresses the question of how to tackle the singularities occurring whenever the observability is lost over largely spaced small time horizons. A particular emphasis is put on the observer design to better appreciate it applicability in sensorless induction motor observer design.…”