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:
May. 15, 2001
Filed:
Jun. 02, 1999
Yoshiaki Doyama, Hirakata, JP;
Hideki Nakata, Neyagawa, JP;
Kaneharu Yoshioka, Katano, JP;
Makoto Yoshida, Kusatsu, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
In a brushless motor driving circuit of the invention, in the starting operation, an applying voltage is low and also the induced voltage is low, so that output values from sample and hold circuits,and,are substantially equal to each other. Thus, an output from a comparing circuit,is substantially equal to an output of a V/f converting circuit,As a result, the starting method which is identical with a conventional method is used. By contrast, when the number of rotation of a brushless motor,is increased, and the induced voltage is started to be observed, the condition is spontaneously shifted to that in which the driving voltage is automatically controlled at each time to an appropriate value for the number of rotation and the load of the motor. Accordingly, the switching operation from the starting control to the normal control is not required.