| Summary: | 博士 === 國立中山大學 === 電機工程學系 === 87 === A novel approach of power-factor-correction with a unified resonant energy tank is proposed for the development of single-stage dc-linked high-frequency load resonant inverters. The high power factor operation is achieved by altering the energy delivery process of the conventional used topologies. The load resonant circuit of the proposed topology draws a high-frequency pulsed current directly from the ac line in stead of the dc-link capacitor. With such an alteration, not only the active power switch but also the energy storage element of the boost-type power-factor-correction circuit can be unified with the existing power switches and load resonant circuit of the inverter. This scheme can be accomplished merely by interposing an additional small capacitor as the energy buffer and a diode as the energy transfer switch, and therefore a high-power-factor inverter can be realized with the most simple, compact, efficient, and cost-effective circuit configuration.
The operating characteristics of several typical load resonant inverter circuit with the proposed power-factor-correction scheme are analyzed in detail, including load variation, open-circuit operation, and duty-ratio regulation. Based on practical considerations, the design equations are derived and the design criteria are deduced accordingly. The input and output profiles are implemented on the applications with special operating features. The implementations are illustrated by various examples. The laboratory circuits were fabricated for the experimental tests to verify the theoretical analyses.
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