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:
Nov. 02, 1976
Filed:
May. 31, 1974
Francis T Thompson, Murrysville, PA (US);
Westinghouse Electric Corporation, Pittsburgh, PA (US);
Abstract
An electric vehicle having a separately excited field controlled direct current drive motor powered by a direct current power supply wherein field current is pulse-width modulated in response to operator control and the vehicle operating parameters. An armature current demand signal which is dependent on a throttle setting is compared with an actual armature current signal derived from an armature shunt and the difference is applied to a field current output amplifier which supplies current to the separately excited field to reduce the difference to zero. The armature current demand signal is responsive to the operator's control of the throttle in the electric vehicle. The drive motor of the electric vehicle can be operated in the driving mode for moving the electric vehicle or a regenerative mode for braking the electric vehicle and supplying energy to the power supply. The armature demand signal is also influenced by various operating conditions to improve operation of the electric vehicle. For example: in a high voltage connection, when regenerative braking voltages increase above a predetermined level the armature current demand signal is reduced; for a low voltage connection with a high current drain, if battery voltage falls below a predetermined level, such as 30 volts, the armature current demand signal is reduced; for high motor speeds above a given value such as 3,000 rpms, the armature current demand signal is reduced to limit commutation sparking; and, when field current excitation falls below a given minimum value the armature current demand signal is also reduced to limit commutator sparking and prevent possible motor damage. During vehicle operation a minimum pulse-width current signal is always applied to the separately excited field of the direct current drive motor to prevent overspeed and motor damage. To maintain smooth control of the electric vehicle, the armature current demand signal relative to a given throttle setting is shifted as a function of motor speed. Compensating means are provided to limit the variation of field excitation as a function of variation in battery voltages.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile