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:
Jul. 08, 1980
Filed:
Jun. 15, 1978
Katsuji Marumoto, Hitachi, JP;
Tsutomu Omae, Hitachi, JP;
Hitachi, Ltd., , JP;
Abstract
A control circuit for controlling supply of current for electric motor has a chopper circuit connected with a battery in series. The chopper circuit is constructed with such as power transistors or power thyristors, and the ON-OFF operation thereof is controlled by a driving pulse. A command signal is produced at a movable tap of a potentiometer, across which a D-C control voltage from the battery is applied. In order to determine the duty and the control frequency of the chopper circuit, a duty controlling oscillator circuit is provided, which generates an output signal on the basis of the command signal from the potentiometer. The duty controlling oscillator circuit includes an integrator composed of an operational amplifier having a negative feedback of a condenser, to the -input terminal of which the command signal is applied. Another operational amplifier having a positive feedback of a resistor operates as a hysteresis comparator, to the +input terminal of which is applied the output from the integrator and to the -one of which a divided reference of the D-C control voltage. In response to the output signal from the hysteresis comparator, a driving pulse generator produces a driving pulse to the chopper circuit.