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:
Oct. 02, 1984
Filed:
Jan. 07, 1983
Leonhard Reng, Erlangen, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
An apparatus for determining the common frequency w of two independently variable a-c quantities is described. In a rotating-field machine, the flux, for instance, is described by two electrical a-c quantities which together determine the magnitude and direction of the field. The two a-c quantities are variable independently of each other and the instantaneous direction of the field is given by an angle.alpha. according to the relation a.sub.1 /a.sub.2 =cotan.alpha., where a.sub.1 and a.sub.2 are the two a-c quantities. In order to determine the frequency of rotation w=d.alpha./dt of the field from these quantities, the quantities a.sub.1 and a.sub.2 are each fed to smoothing stages and thence to a computing circuit, wherein the quotient (d.sub.1 .multidot.a.sub.2 -d.sub.2 .multidot.a.sub.1)/(d.sub.1 .multidot.a.sub.1 +d.sub.2 .multidot.a.sub.2) proportional to the frequency is formed from a.sub.1 and a.sub.2 and the smoothed quantities d.sub.1 and d.sub.2. The use of differentiators is thereby avoided, which would cause a phase error as well as difficulties when harmonics of the quantities a.sub.1 and a.sub.2 are present.