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:
Feb. 27, 2001
Filed:
Jul. 07, 1999
Hitachi, Ltd., Tokyo, JP;
Abstract
An apparatus for steadily and efficiently controlling a synchronous motor is equipped with a function for generating dq-axis current commands so that the terminal voltage of the synchronous motor may not exceed the voltage which a power converter can output even at a current transition time, a current control function for correcting a fluctuation of a D.C. input voltage, and a function for eliminating the D.C. input power to zero when performing field weakening control. The dq-axis current command generator is so built as to retrieve current command tables listing high-efficiency data in advance by torque commands and rotational speeds of the synchronous motor. There are a plurality of current command tables converting maximum terminal voltages of the synchronous motor. A means is provided to select an optimum one of said current command tables according to the D.C. input voltage. In this case, a value obtained by subtracting a preset value from the D.C. input voltage is used for this selection of an optimum current command table.