An experimental performance test of a derivative-free non-linear state observer designed for sensorless AC drives

In this paper, a new Kalman filtering technique, unscented Kalman filter (UKF) is utilized both experimentally and theoretically as a state estimation tool in field-oriented control (FOC) of sensorless AC drives. Using the advantages of this recent derivative-free nonlinear estimation tool, rotor speed and dq-axis fluxes of an induction motor are estimated only with the sensed stator currents and voltages information. In a previous study, simulations has shown that, UKF, whose several intrinsic properties suggest its use over EKF in highly nonlinear systems, has highly satisfactory rotor speed and flux estimates, which are the most critical states for FOC. In this new work, those simulation results are supported with experimental results.