Research on Extreme Low Speed Performance of Speed Sensorless Vector Control System of Induction Motor

This paper proposes an improved algorithm for the problems of weakening of the motor flux, system instability, and poor load capacity due to the significant increase in the proportion of the inverter's nonlinear voltage and stator resistance voltage drop due to the significant increase in the proportion of the system in the extremely low-speed area. By establishing the observer state error equation in terms of the Nonlinear Voltage Error (NVE) of inverter, Stator Resistance Voltage Drop (SRVD), and expounding the influence of NVE on the estimated speed, a feedback matrix that can reduce NVE of the inverter and the influence of SRVD on the speed estimation is develop. Meantime, the traditional adaptive law is improved. Namely, a compensation amount, on the basis of traditional adaptive law, is introduced to compensate the flux error caused by the NVE of the inverter and the SRVD.