Online Inductance Estimation of Speed Sensor less Induction Motor Drives

Induction motor (IM) drives with field-oriented control scheme are widely used in the industry. Motor drives with speed sensors (encoders) decreases the reliability and robustness of the system in hostile environments. This increases the demand for speed sensorless motor drive schemes. For speed sensorless control of IM, speed needs to be estimated, and speed can be estimated from the stator flux information. But this speed estimation method requires the information of stator, rotor, and mutual inductances of the motor, which are conventionally obtained by the testing the motor at standstill. Instead, these parameters can be estimated online from the voltage and current information of the motor. An online inductance estimation scheme for speed sensorless Field Oriented Controlled (FOC) Induction motor drives is proposed in this paper. Stator leakage inductance is estimated based on the current error and rotor flux. Rotor inductance and mutual inductance are estimated from this estimated stator leakage inductance. The proposed scheme for online inductance estimation is validated through extensive simulation in MATLAB-SIMULINK platform.