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:
Nov. 06, 2012
Filed:
Nov. 04, 2009
Yoshihiro Matsumoto, Suzuka, JP;
Yoshihiro Matsumoto, Suzuka, JP;
Fuji Electric Co., Ltd., , JP;
Abstract
An inverter device is provided that can measure a decrease in cooling capacity caused by a finite service life of a cooling fan or clogging of a cooling fin, without being affected by an ambient temperature or a load state. A thermal time constant is calculated in a thermal time constant calculation circuit from a temperature detection value from a temperature detection circuit and a time signal from a timer on the basis of an operation/stop command for the inverter device. The calculated value of the thermal time constant calculated in the thermal time constant calculation circuit is compared by a comparator with a reference value of the thermal time constant that is stored in advance in a memory. Whether the cooling capacity has decreased is determined based on the comparison results.