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. 15, 1985
Filed:
Jan. 25, 1983
Keiji Sakamoto, Hachioji, JP;
Shinji Seki, Tokyo, JP;
Fanuc Ltd, Minamitsuru, JP;
Abstract
To reduce adverse effects due to a dead zone in a pulse-width modulation circuit provided for avoiding short-circuiting in an inverter circuit, distortions of sine wave currents generated when low-frequency current commands are given, sound produced due to the excitation, and torque variations, a synchronous motor drive apparatus has been provided. The apparatus comprises a current detector circuit for detecting drive currents given to the synchronous motor, a difference output circuit for producing as outputs the differences between current commands given to the synchronous motor and the detected currents, a pulse-width modulation circuit for modulating signals indicative of the differences by way of pulse-duration modulation, an inverter circuit for driving the synchronous motor, a voltage detector circuit for detecting output voltages from output terminals of the inverter circuit, and a circuit for generating the differences between output voltages from the difference output circuit and the detected output voltages, whereby the synchronous motor can be driven by the outputs from the inverter circuit which is operated by voltage command values indicating the last-mentioned differences.