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. 03, 1988
Filed:
Dec. 22, 1986
Masami Nomura, Inazawa, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
Three pairs of reversed polarity thyristors 20a,21a; 24a,25a; 28c,29c are connected directly between the three phases R, S, T of an AC power source and the corresponding phases of an elevator drive motor 5. The two pairs connected to the R and S phases implement upward driving, and the third pair connected to the T phase is used for both upward and downward driving but is held non-conductive during regenerative braking/deceleration when the motor operates in a two phase mode. Two additional thyristor pairs 22b,23b; 26b,27b which are used for downward driving are cross-connected between the R and S power source phases and two of the motor phases, to thus reverse the direction of motor rotation. Different individual thyristors in the pairs coupled to the R and S phases are selected in upward and downward deceleration modes. The overall circuit arrangement and firing selection/control scheme is designed to implement load sharing between the various thyristors and thus minimize duty cycle differences.