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Switched Capacitor Energy Buffer Architecture

Technology Benefits

High energy density because the switching network is operated such that while the voltage seen at the buffer port varies only over a small range, the voltage of the individual capacitors varies over a wide range.-Longer life and higher reliability because film capacitors are used instead of electrolytic capacitors.-High efficiency because the switching network need operate at only very low (line-scale) switching frequencies.-Reduce loss by taking advantage of soft charging of the energy storage capacitors.-High efficiency across the full operating range because the proposed buffer architecture exhibits losses that reduce as energy buffering requirements reduce.

Technology Application

Power conversion systems

Detailed Technology Description

None

Supplementary Information

Inventor: POON, Ngaikit, Franki | PONG, Manhay | LIU, Chiupong, Joe
Priority Number: WO2005046038A1
IPC Current: H05B004128 | H05B0041282 | H05B0041392
Assignee Applicant: The University of Hong Kong
Title: DIMMABLE BALLAST WITH RESISTIVE INPUT AND LOW ELECTROMAGNETIC INTERFERENCE | BALLAST A INTENSITE REGLABLE A ENTREE RESISTIVE ET FAIBLE NIVEAU D'INTERFERENCE ELECTROMAGNETIQUE
Usefulness: DIMMABLE BALLAST WITH RESISTIVE INPUT AND LOW ELECTROMAGNETIC INTERFERENCE | BALLAST A INTENSITE REGLABLE A ENTREE RESISTIVE ET FAIBLE NIVEAU D'INTERFERENCE ELECTROMAGNETIQUE
Summary: Alternating current to alternating current conversion apparatus for ballast or gas discharge lamp, cold cathode fluorescent lamp, high intensity discharge (HID) lamp.
Novelty: Alternating current-alternating current power conversion apparatus for e.g. fluorescent lamp, has terminal which is connected through primary winding to voltage source that charges or discharges capacitor within pulsating cycle

Industry

Optics

Sub Category

Lighting

*Abstract

Problem:Power conversion systems that interface between dc and single-phase ac need energy storage to provide buffering between the constant power desired by a dc source or load and the continuously varying power desired for a single-phase ac system. While electrolytic capacitors are generally used to provide high-density energy storage for buffering, their limited-life and reliability are a concern. Film capacitors have much longer life and higher reliability, but an order of magnitude lower peak energy density. Therefore, for long-life and compact grid-interface systems there is a strong interest in developing energy buffers based on film capacitors that provide effective energy density comparable to electrolytic capacitors.Technology:This patent describes the Stacked Switched Capacitor (SSC) energy buffer, which is composed of two series connected blocks of switches and capacitors. It works on the principle that while the voltages of individual capacitors can vary over a wide range, the voltage at the buffer port remains constrained to a desired narrow range. By using long-life capacitors that can be efficiently charged and discharged over a wide voltage range (e.g., film capacitors) it achieves effective energy densities comparable to electrolytic capacitors and much longer life.

Country/Region

USA