Sensorless Vector Control for Induction Motor with Rotor Flux Observer

회전자 자속 관측기를 사용한 유도전동기의 센서리스 벡터제어

In order to implement the direct vector control type sensorless vector control, the rotor flux and the angular speed of the rotor can only be estimated through the measurement of the stationary voltage and current states. To estimate the rotor flux, the use of the rotor flux observer(RFO) has been proposed. It is known that the RFO is relatively insensitive to parameter variations. Using the rotor flux value obtained from the RFO, the rotor flux vector can be estimated. The angular speed of the rotor is estimated by the difference between the synchronous angular speed and the slip angular speed, both of which are derived from the rotor flux vector. However unwanted high order frequency waves become incorporated into the synchronous angular speed during calculations. Thus we propose the use of digital filters that will eliminate these high frequency waves. We have demonstrated through computer simulations that the use of filters results in stable system activity over a wide speed range and good response to load variations.