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:
Aug. 17, 1982
Filed:
Oct. 18, 1979
Hitachi, Ltd., Tokyo, JP;
Abstract
A thyristor chopper whose gate signal is controlled by a magnetic phase shifter is connected between a battery and a series motor of an electric vehicle and is short-circuited by a bypass contactor as soon as the duty factor of the chopper attains 100%. In the short-circuited condition of the chopper, the magnetic phase shifter remains idle and does not participate in the control operation although the instruction current and the actual motor current are kept applied to its control windings. Therefore, the level of the output from the magnetic phase shifter is indicative of the value of the actual motor current when the instruction current value is fixed, so that the actual motor current value can be detected by detecting the output level from the magnetic phase shifter. When the actual motor current value is detected to be excessively large, the bypass contactor short-circuiting the chopper is released to decrease the value of the motor current, while when the actual motor current value is detected to be excessively small, a field-weakening contactor is closed to connect a field-weakening resistor in parallel with the field winding of the series motor so as to accelerate the motor by the field-weakening control.