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:
Apr. 18, 2000
Filed:
Sep. 10, 1998
Eiji Yamada, Owariasahi, JP;
Yasutomo Kawabata, Aichi-ken, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
The conventional technique can not detect the electrical angle of a synchronous motor in a sensor-less manner when a high torque is required under the condition of a low-speed operation of the motor. The direction that passes through the axis of rotation of the motor and causes a magnetic flux to pass through a permanent magnet is defined as a d axis, whereas the direction that is electrically perpendicular to the d axis in the plane of rotation of the motor is defined as a q axis. In the case where the motor is required to output a high torque, the technique of the present invention applies a predetermined detection voltage to the q axis and determines the electrical angle based on the ratio of electric currents flowing through the d axis and the q axis. Application of a negative voltage to the q axis relieves magnetic saturation occurring on the q axis under a high torque condition and thereby allows detection of the electrical angle. When a positive voltage is applied to the q axis, on the other hand, the technique of the present invention refers to a table which is stored in advance to represent the one-to-one mapping of the electrical angle to the electric current flowing through the q axis, and thereby determines the electrical angle.