Filing Information

Inventor(s)	Motomi Shimada · Akira Horie ·
Assignee(s)	Hitachi, Ltd. ·  View assignee updates
Attorney/Agent(s)	Antonelli, Terry, Stout and Kraus, LLP. ·
Primary Examiner	Lincoln Donovan ·
Assistant Examiner	Tyrone Smith ·
Application Number	US11107737
Filing date	04/18/2005
Issue date	02/13/2007
Prior Publication Data	US20050184693 - 08/25/2005
Predicted expiration date	06/27/2023
Patent term adjustment	3
U.S. Classifications	318/432  · 318/376  · 318/371  · 318/374  · 318/436  · 701/19  · 701/20  · 318/434  ·
International Classifications	H02P700  ·
Kind Code	B2
Related U.S. Application Data	CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. application Ser. No. 10/601,629, filed Jun. 24, 2003, now abandoned, the contents of which are incorporated herein be reference.
Foreign Priority	JP2002188978 - 06/28/2002 ·

Patent Family

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.

Independent Claims | See all claims (8)

1. 1. A control apparatus for an electric railcar comprising: an electric power converter for driving a motor; means for detecting the rotational speed of said motor; means for controlling said electric power converter; means for decreasing the braking torque of said motor gradually from a first braking torque to a second predetermined braking torque which is larger than zero and smaller than said first braking torque when an AND condition which indicates the brake command is in existence and the rotational speed of said motor decreases below a first predetermined speed is satisfied; and means for maintaining the braking torque of said motor constantly to said second predetermined braking torque until the rotational speed of said motor becomes zero.
2. 3. A control apparatus for an electric railcar comprising: an electric power converter for driving a motor; means for detecting a rotational speed of said motor; means for controlling said electric power converter; means for creating PWM signals with a first carrier frequency; means for controlling switching elements constituting said electric power converter using said PWM signals; and means for selecting a second carrier frequency which is lower than said first carrier frequency for creation of PWM signals when an AND condition which indicates the brake command is in existence and the rotational speed of said motor decreases below a predetermined low speed is satisfied.
3. 5. A control apparatus for an electric railcar comprising: an electric power converter for driving a motor; means for detecting a rotational speed of said motor; means for controlling said electric power converter; means for decreasing the braking torque of said motor gradually from a first predetermined braking torque to a second braking torque which is larger than zero and smaller than said first braking torque when an AND condition which indicates the brake command is in existence and the rotational speed of said motor decreases below a first predetermined speed is satisfied; means for maintaining the braking torque of said motor constantly to said second predetermined braking torque until the rotational speed of said motor becomes zero; means for creating PWM signals with a first carrier frequency; means for controlling switching elements constituting said electric power converter using said PWM signals; and means for selecting a second carrier frequency which is lower than said first carrier frequency for creation of PWM signals when an AND condition which the brake command is in existence and the rotational speed of said motor decreases below a predetermined low speed is satisfied.