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:
Feb. 13, 2007
Filed:
Apr. 18, 2005
Motomi Shimada, Hitachinaka, JP;
Akira Horie, Hitachinaka, JP;
Motomi Shimada, Hitachinaka, JP;
Akira Horie, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A control apparatus for an electric railcar that provides control so that when rotational speed of a motor decreases below a required value, torque of the motor will decrease at a required rate of change, a current limiter for limiting a torque current command '(A)Iqp' output from a current command arithmetic unit is provided to ensure that when the rotational speed of the motor decreases below the required value, the torque current command will be limited to a command value '(B)Iqp' smaller than that command value, and to ensure that a carrier frequency at which PWM signals are created when switching elements of the electric power converter are controlled by carrier generator is controlled to become lower than a carrier frequency existing when the rotational speed of the motor decreases below the required value.