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:
May. 06, 2003
Filed:
Mar. 06, 2002
Joseph R. Rostron, Hampton, GA (US);
SSI Power, LLC, Hampton, GA (US);
Abstract
A voltage sag and over-voltage compensation device for an AC electric power distribution system employing cascaded switching devices and a pulse width modulated autotransformer. The autotransformer typically includes lower, center, and upper poles or taps with cascaded switching devices for selectively connecting the voltage source (i.e., a phase of the distribution line) between the lower pole and the center or upper poles. Each stage of the cascaded switching device includes a switching element located within a full-bridge rectifier circuit to allow bi-directional switching through each switching element (i.e., switching through the same switching element during the positive and negative portions of the AC voltage cycle). Each full-bridge rectifier also includes a snubber circuit connected in parallel with a corresponding switching element to absorb the current discharge caused by switching the input power supply to the autotransformer through the corresponding switching device under non-zero current conditions. On the output side, the voltage sag and over-voltage compensation device includes a load capacitor to smooth the voltage-corrected AC power supply toward a sinusoidal power supply at the system frequency, and a notch filter to remove noise created by the switching elements.