State and Parameter Estimation of Induction Motor through Adaptive High Gain Observer

Abstract

Induction motor is the most widely used electric motor in industry, EVs and HEVs due to high reliability, ruggedness, low cost of maintenance, high torque during starting and wide range of operating speed. However, highly non-linear dynamics of induction motor make it difficult to control as compare to other motors. With the development of field oriented control, the induction motor can be controlled like separately excited dc motor. Field oriented control requires the exact information of rotor flux. Since the rotor flux is not easy to estimate due to the large variations in the parameters of induction motor due to the surrounding and operating temperature. Rotor resistance and rotor inductance are crucial parameters for estimation of flux. The objective of simultaneous estimation of fluxes along with critical parameter is achieved through adaptive high gain observer. The observer estimate the actual values of rotor resistance and rotor inductance under persistence excitation condition which guarantees the exact estimation of rotor flux.