A new direct field oriented controller employing rotor end ring current detection

Abstract

A novel direct field-oriented control scheme for induction motor drive applications that employs rotor end ring current detection and removes the dependence of the controller accuracy on temperature is presented. This field orientation scheme does not require an incremental encoder for rotor position sensing. The motor torque can be accurately controlled even down to zero frequency operation. The controller is completely independent of rotor time constant variations. The rotor end ring current is measured via Hall-effect sensors. An adaptive controller for the rotor current gains eliminates the error introduced in the measurement due to temperature changes of the Hall sensors. Consequently, the field-oriented controller remains robust, even for conditions where the machine internal air temperature reaches 100 degrees C. Experimental results showing the practical feasibility of the proposed direct field-oriented controller are presented. >