Experimental Estimation of Sudden Torque Changes in a PMSG Using a Luenberger Time-Varying Observer

This paper proposes a new Luenberger observer designed to estimate all mechanical parameters required for controlling a permanent magnet synchronous generator (PMSG), such as angular position, rotational speed, mechanical torque and jerk (derivative of acceleration). The design is based on a fourth-order model that uses the relationship between currents and voltages to improve accuracy and robustness against noise. The observer can track sudden variations of the mechanical torque, which is not possible with conventional Luenberger observer, Kalman filter or sliding mode observer. For a salient-pole machine, the system is time-varying: the observer stability and convergence are proved using the theory of linear time-varying systems. MATLAB Simulink simulations and experiments with a 1.5 kW machine were carried out to validate the observer performance in comparison to conventional ones. The results show that the proposed observer can accurately estimate mechanical torque variations greater than 5 N m for jerks lasting less than 0.1 s.