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:
Jun. 03, 1997
Filed:
Jun. 07, 1995
Matthias Rebhan, Fuerth, DE;
Hubert Schierling, Erlangen, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
The invention relates to a method and apparatus for recognizing a standstill condition when restarting a power converter-fed AC motor without a tachometer generator. According to an embodiment of the invention, a standstill recognition method includes first and second active phases decoupled by a passive phase. In each phase, time characteristics of the orthogonal current components of a measured motor current are recorded, and the energy component of current from the second active phase is further evaluated to generate an average value. This generated average value and an upper range value are then compared to a limiting value, which will be exceeded when the AC motor is at a standstill. Thus, through application of a current measurement and a simple evaluation, one can quickly determine the actual state of the power converter-fed AC motor when restarting.