Flux estimation algorithms for electric drives: A comparative study

This paper reviews the stator flux estimation algorithms applied to the alternating current motor drives. The so-called voltage model estimation, which consists of integrating the back-electromotive force signal, is addressed. However, in practice, the pure integration is prone to drift problems due to noises, measurement error, stator resistance uncertainty and unknown initial conditions. This limitation becomes more restrictive at low speed operation. Several solutions, reported in the literature, are reviewed and compared. Emphasis is placed on the low-pass filter based algorithms that show good performance in steady-state as well as in transient operating conditions.