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:
Sep. 05, 1978
Filed:
Nov. 04, 1976
Robert M Oates, Murrysville, PA (US);
Theodore M Heinrich, Murrysville, PA (US);
White-Westinghouse Corporation, Pittsburgh, PA (US);
Abstract
An apparatus for inductively heating cooking utensils comprising four induction cooking coils excited by a central power oscillator providing an alternating sinusoidal excitation voltage at about 25 kilohertz which is 100% amplitude modulated at 120 hertz. Power to the four induction coils is duty cycle controlled by four 60 hertz triacs each series inserted between the power oscillator and a respective one of the induction coils. The triacs switch to excite their respective induction coils only at the zero point of the excitation voltage modulation envelope. Line power fluctuations are minimized by sequential switching of the triacs in a manner that results in an effective power switching frequency of approximately 46 hertz when all four induction cooking coils are excited. The central power oscillator is inherently protected from high Q load conditions without the provision of feedback loops.