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:
Dec. 23, 2025
Filed:
Jul. 30, 2021
Fanuc Corporation, Yamanashi, JP;
Taku Sasaki, Yamanashi, JP;
FANUC CORPORATION, Yamanashi, JP;
Abstract
This motor drive device comprises: a motor drive circuit that drives a synchronous motor by supplying AC power to the synchronous motor via power lines; an overvoltage protection circuit that short-circuits between the phases of the power lines by turning on a semiconductor switch when driving of the synchronous motor by the motor drive circuit is stopped and prevents the occurrence of overvoltage due to a back electromotive force between the terminals of the synchronous motor; and a temperature estimation unit that calculates a temperature estimation value of the semiconductor switch by using a motor constant and a semiconductor switch constant, said motor constant including at least one of the inertia and back electromotive force constants of the synchronous motor, said semiconductor switch constant including the on-resistance, thermal resistance, and thermal time constant of the semiconductor switch.