Speed-sensorless drive for induction machines using a novel hybrid observer

This paper proposes a hybrid state observer which combines a Luenberger observer and a sliding mode observer for speed-sensorless motor drives of induction machines. The stator current and rotor flux linkage is estimated following a Luenberger observer approach. The rotor speed is estimated using a sliding mode observer. The combination of two observers take advantage of both. Luenberger observer is easy to accomplished and the computation burden is small. Sliding mode observer is know for its robustness with respect to model parameter errors and it will also provide a fast convergence rate. The chattering of the sliding mode observer is addressed by applying a boundary layer. Simulation results show the performance of the proposed observer. Hardware validation results are also presented and discussed.