Flux tracking in induction machines by means of volt-ampere quantities

It is demonstrated that an instantaneous quantity related to average reactive power can be defined for machines with three-phase sinusoidally distributed windings. Expressions for the flow of this quantity into the stator of an induction machine are obtained and interpreted in terms of the behavior of flux distributions within the machine. These results are used to devise an algorithm for tracking the rotor flux inside an induction machine without dependence on stator or rotor resistance and without the need for motor modifications. Application of this algorithm to a field-oriented control system utilizing a voltage-source current-controlled inverter is investigated. Computer simulations are presented to support the theoretical results