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. 31, 1989
Filed:
Jun. 18, 1987
Makoto Nohmi, Kawasaki, JP;
Eiji Kozu, Ehime, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
The magnitude of current change for the change of input voltage or for the change of speed of rotation of the shunt motor is utilized, i.e., the shunt characteristics are utilized, and the voltage applied to the motor is limited so that the armature current decreases by an amount that corresponds to the increase in the armature voltage when slipping and to the decrease in the armature voltage when sliding have taken place, thereby to obtain improved adhesion characteristics. For this purpose according to the invention, an electromotive force of the motor is calculated from a motor speed detected by a detector and from a field current of the motor, a voltage drop caused by the motor resistance and the motor current is calculated, a motor voltage is calculated by adding the thus calculated voltage drop to the electromotive force of the motor, and the voltage applied to the motor is limited depending upon the calculated motor voltage.