A full-order sliding mode flux observer with stator and rotor resistance adaptation for induction motor

For resolving the imprecise flux estimation caused by parameters variation of induction motor, a full-order sliding mode flux observer with stator and rotor resistance adaptation is proposed in this paper by constructing the state equations with the stator currents and rotor flux as variables. This scheme identifies stator and rotor resistances during flux estimation, updating the changing stator and rotor resistance of flux estimation system to ensure the robustness of the whole parameter estimation operation. Taking the advantage of the second order low-pass filter characteristic of the designed observer, the high-frequency switching noise contained in the flux can be filtered without the addition of extra low-pass filter. The observer is applied to the direct torque control (DTC) of induction motor to achieve good control performance. The simulation results validate the feasibility and effectiveness of the proposed algorithm.