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:
Jan. 18, 2005
Filed:
Jul. 08, 2003
Keijiro Sakai, Kanasagou, JP;
Toshiaki Okuyama, Tokai, JP;
Kinya Nakatsu, Hitachi, JP;
Hiroyuki Tomita, Funabashi, JP;
Junji Kato, Takaishi, JP;
Teiichi Furukawa, Narashino, JP;
Keijiro Sakai, Kanasagou, JP;
Toshiaki Okuyama, Tokai, JP;
Kinya Nakatsu, Hitachi, JP;
Hiroyuki Tomita, Funabashi, JP;
Junji Kato, Takaishi, JP;
Teiichi Furukawa, Narashino, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An inverter apparatus for converting a DC power converted from an input AC power to an output AC power of a variable frequency and a variable electric power to drive an induction motor at a variable speed. The inverter apparatus includes a rectifying unit, a filter capacitor, an inverter unit having an input connected across the filter capacitor, an input current detector and a gate circuitry for driving the inverter unit. An excitation current detection unit detects an excitation current of the induction motor from an output signal of the input current detector, a gate signal for driving the gate circuitry and a reference phase command. A setting unit sets a limitation level of the excitation current, a torque boost voltage command unit produces a torque boost voltage command, and a torque boost voltage compensation unit changes the torque boost voltage command so that the detected excitation current value is smaller than or equal to the limitation level.