Model reference adaptive system observer based sensorless control of doubly-fed induction machine

This paper presents a sensorless algorithm for the vector control of doubly-fed induction Machine (DFIM) using rotor current based model reference adaptive system (MRAS) observer. The stator flux oriented vector control is employed to achieve variable-speed drive and decoupled active/reactive power control. In the proposed MRAS observer, the reference model is the measured rotor current, which compared to the estimation of the rotor current obtained from measured stator voltages and currents. A proportional-integral (PI) control adjusts the rotational rotor angle, driving the error between the measured and estimated rotor currents to zero. A 50kW DFIM prototype system is built to verify the theoretical analysis. Through variable speed tracking control in motoring mode and decoupled active/ reactive power control in generating mode for simulation and laboratory experimental study, even if the magnitude of rotor current is very low, closing to zero, the estimation of rotational speed and rotor position at different speed and power condition can still track the actual value. The simulation and laboratory experimental results have shown the effectiveness of the proposed sensorless control scheme.