Method of correcting flux midpoint in flux-controlled alternating current systems

摘要

The invention relates to a method of correcting the flux midpoint in flux-controlled alternating current systems, the method comprising the steps of determining a stator flux estimate (&psgr;_s,est) and determining the magnitude of stator current (i_s). The method is characterized by the steps of forming the scalar product between the stator flux estimate (&psgr;_s,est) and the stator current (i_s) in order to obtain a reference variable (k), low-pass filtering the reference variable (k) in order to obtain a low-frequency component (k_filt) of the reference variable (k), subtracting the low-frequency component (k_filt) from the reference variable (k) in order to obtain a difference variable (e), determining correction term components (&psgr;_s,x,corr, &psgr;_s,y,corr) of the staror flux estimate (&psgr;_s,est) by multiplying the difference variable (e) by the components (&psgr;_s,x,est, &psgr;_s,y,est) of the stator flux and correction coeficient (K_&psgr;corr), and forming a stator flux (&psgr;_s,fin) with a corrected midpooint on the basis of the components (&psgr;_s,x,est, &psgr;_s,y,est) of the stator flux estimate and correction term components (&psgr;_s,x,corr, &psgr;_s,y,corr).