I-F Start-Up Procedure of an Induction Machine with Smooth Transition to Sensorless Vector Control

The focus of this article is the start-up procedure from standstill to target speed, which is tested on a motor test bench subsequently. It is a common problem of sensorless vector control, that the model for the flux estimator does not deliver reasonable results at low rotation speeds and especially at standstill. In this paper an I-f start-up is deployed in the low-speed range, afterwards a smooth transition to field-oriented control is performed. Finally, the sensorless vector control of an induction machine will be used in a project dealing with a reciprocating compressor as mechanical load, which is not covered here.