A new hybrid vector control for induction motor without speed and position sensors-frequency hybrid approach using new indirect scheme

This paper proposes a new hybrid vector control scheme for induction motors without speed and position sensors. It has the following interesting and distinguished features. The employed field orientation is pure rotor flux orientation. The field orientation scheme requires neither velocity nor position estimation at all. It is a completely seamless hybrid of indirect and direct orientation schemes and the indirect scheme is quite new and simple. Estimates of both rotor and stator fluxes can be obtained. It is completely free from variation of rotor electrical parameters in most operating cases. An instant estimate of rotor velocity for speed control is available. Rigorous numerical experiments are carried out in order to examine torque response with constant velocity in both motoring and regenerating operations, torque response in four-quadrant operation with variable velocity and speed response to variable commands in which maximum and minimum values are 500 and 1(rad/sec) respectively and acceleration and deceleration are /spl plusmn/400(rad/sec/sup 2/). Results show the high potential usefulness of the proposed hybrid scheme.