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:
Dec. 02, 1997
Filed:
Dec. 18, 1995
Craig S Ranta, Redmond, WA (US);
David S Nierescher, Newcastle, WA (US);
Steven M Swedenburg, Seattle, WA (US);
Selfcharge, Inc., Bellevue, WA (US);
Abstract
A battery pack for an electrical device contains rechargeable batteries for supplying power to the electrical device and a transformerless pulse charging circuit. The pulse charging circuit generates a pulse charging current from received AC current, and charges the rechargeable batteries with the generated pulse charging current. A semiconductor switch (12) generates the pulse charging current from the received AC current and supplies the pulse charging current to the batteries. A ramp generator circuit (14) generates a linearly rising waveform beginning at each zero crossing of the rectified AC current. A current sense amplifier circuit (15) measures the average value of current pulses through the battery and generates a signal proportional to an average charging current. A triggering circuit (18) generates the gate firing pulses for the semiconductor switch (12) according to the linearly rising waveform and the average charging current amplifier waveform.