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. 11, 2011
Filed:
Jun. 09, 2008
Michael Strnad, Kassel, DE;
Neidhardt Bechtel, Kassel, DE;
Christian Hardt, Kassel, DE;
SMA Solar Technology AG, Niestetal, DE;
Abstract
The subject matter of the invention is a method for detecting an isolated network for an inverter () carrying a converter voltage that is adapted for connection in parallel with a grid () having a mains frequency and electric loads and that is decoupled from the grid () by a choke (), a test signal being superimposed upon the converter voltage at a test frequency the frequency of which is smaller than the mains frequency, the amplitude of the test signal being much smaller than the nominal voltage amplitude of the mains voltage on the one side but still just large enough on the other side for changes in reactive power to be detectable as a result of the test signal, a reactive power share being determined, which oscillates with the test frequency, this share not being allowed to fall below an imposed minimum for an isolated operation to be reliably excluded.