Sensorless control of direct-field-oriented induction motor operating at high efficiency using adaptive rotor flux observer

The speed sensorless control of direct-field-oriented induction motors using an adaptive rotor flux observer was developed recently. This method drives the induction motor using a constant-rated rotor flux in order to estimate rotor speed without loss of accuracy and to prevent degeneration of dynamic response. However, the driving efficiency of the field-oriented induction motor must be maximized for applications such as electric vehicles which have a limited power supply. The authors apply rotor flux control which enables high-efficiency sensorless direct-field-oriented induction motor systems to be developed. Using experimental and simulation results, this paper shows the advantages of sensorless direct-field-oriented induction motor control using an adaptive rotor flux observer