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. 21, 2019
Filed:
Aug. 11, 2017
GM Global Technology Operations Llc, Detroit, MI (US);
Gilsu Choi, Shelby Township, MI (US);
Anno Yoo, Rochester Hills, MI (US);
Dwarakanath V. Simili, Oakland Township, MI (US);
GM GLOBAL TECHNOLOGY OPERATIONS LLC, Detroit, MI (US);
Abstract
A method in a motor controller for an electric motor is disclosed. The method includes receiving a motor current measurement, a motor reference voltage or measured voltage, and an estimated temperature from the electric motor, determining a reference flux linkage estimate (λpm,ref) from a lookup table based on the motor current measurement and the estimated temperature, determining a back-EMF (electromotive force) estimate based on the motor current measurement, the motor voltage and the estimated temperature, determining an observed flux linkage estimate (λpm,obs) from the back-EMF estimate, determining a magnetic strength as a ratio of the observed flux linkage estimate to the reference flux linkage estimate, and determining that a rotor magnet has been demagnetized to an unacceptable level when the magnetic strength is below a threshold level.