The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 01, 2002
Filed:
Sep. 26, 2000
Markku Niemelä, Lappeenranta, FI;
ABB Industry Oy, Helsinki, FI;
Abstract
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; ) and determining the magnitude of stator current (i ). The method is characterized by the steps of forming the scalar product between the stator flux estimate (&psgr; ) and the stator current (i ) in order to obtain a reference variable (k), low-pass filtering the reference variable (k) in order to obtain a low-frequency component (k ) of the reference variable (k), subtracting the low-frequency component (k ) from the reference variable (k) in order to obtain a difference variable (e), determining correction term components (&psgr; , &psgr; ) of the staror flux estimate (&psgr; ) by multiplying the difference variable (e) by the components (&psgr; , &psgr; ) of the stator flux and correction coeficient (K ), and forming a stator flux (&psgr; ) with a corrected midpooint on the basis of the components (&psgr; , &psgr; ) of the stator flux estimate and correction term components (&psgr; , &psgr; ).