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. 01, 1986
Filed:
Nov. 07, 1984
Applicant:
Inventor:
John M Leuthen, Claremore, OK (US);
Assignee:
Hughes Tool Company, Houston, TX (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02M / ;
U.S. Cl.
CPC ...
363 87 ; 363129 ;
Abstract
An SCR firing circuit allows the firing point to be changed. The firing circuit includes a ROM which has an output for each gate of each SCR. The ROM is programmed to fire the SCRs in a desired sequence. The ROM is driven by a counter, which counts pulses from an oscillator, the frequency of which is variable. The difference between the zero cross of the waveform and the ROM output is compared and averaged. The comparator output is summed with a variable DC demand voltage. The sum is applied to an integrator, which provides an integrated output to the oscillator to change the frequency of the oscillator if the firing point is changed.