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:
Oct. 21, 1997
Filed:
Sep. 22, 1995
Richard Redl, Onnens, CH;
Toko, Inc., , JP;
Abstract
A pulse width modulated controller controls a zero-voltage switching resonant power converter or inverter. The on time of the power switch (110) of the converter or inverter is varied by an error amplifier (280) such that the output voltage of the converter or inverter maintains proportionality to a reference voltage (290). The off time is terminated by a switch-voltage detector (320) when the voltage across the power switch (110) drops below a threshold voltage (330) due to the natural resonance of the external resonating capacitor (120) and inductors (130 and 150). In the first two embodiments of the invention, a single timing capacitor (260) is employed both for determining the on time and the off time. In two other embodiments, two timing capacitors (262 and 264) are employed for separately determining the maximum allowed off time and the variable on time. A cycle-by-cycle current limit circuit comprising a current sensor (605), a comparator (610), and an R-S latch (620) may be added to the circuits representing each of the embodiments. By incorporating a soft start subcircuit (775) and an overlap detector (710, 715, 20, 725), protection against overdissipation of the power switch caused by loss of zero-voltage switching can also be implemented. The soft start subcircuit can also be triggered by a voltage detector (740, 745), which monitors the output voltage of the power converter or some other voltage within the system, such as the peak voltage across the power switch (110), to effectively implement overvoltage protection.