Simplified flux estimation for control application in induction machines

This paper deals with the problem associated with a pure integrator in the estimation of stator flux linkage in induction machines and proposes a solution. Integration error in a flux estimation system comprises a drift produced by the integrator, somehow related to an initial condition, and the drift produced by an error present in the back electromotive force (EMF) due to measurement offset error in the terminal voltage and/or phase current. The performance of the induction machine control mainly depends on the accuracy of the estimated flux. The proposed method compensates the error produced by the inherent problem in the pure integrator and measurement error. This method can be easily applied in a DSP based induction machine control system to estimate the flux. The execution time required to implement the proposed system is small such that there will not be much software computation burden.