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Control of high-frequency AC link electronic transformer

Krishnaswami, H and Ramanarayanan, V (2005) Control of high-frequency AC link electronic transformer. In: IEE Proceedings of Electric Power Applications, 152 (3). pp. 509-516.


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An isolated high-frequency link AC/AC converter is termed an electronic transformer.The electronic transformer has size and cost advantages over a conventional transformer because of high-frequency operation of the magnetic core. Of the various topologies of electronic transformer, the high-frequency AC link electronic transformer achieves high-frequency AC power transformation without a DC link. The circuit uses the standard H-bridge, one on either side of the high-frequency transformer. A novel PWM scheme is proposed, which symmetrically delays and advances the phase of the left and right legs of the front-side converter with respect to the output side converter. The proposed scheme introduces free wheeling sub-periods, which results in zero voltage switching in the output-side converter. The electronic transformer as an AC automatic voltage regulator (AVR) offers distinct advantages over a conventional servo voltage stabiliser in terms of size and speed of response. The AVR application is discussed and experimental results of a 500VA AVR are presented. A four-quadrant switch presents difficulties in turning off inductive load current because of the absence of a free wheeling path in the switch. A biasing circuit is proposed to convert the potentially lossy switching transition into lossless transition. Simulation and experimental results with the biasing circuit are presented.

Item Type: Journal Article
Publication: IEE Proceedings of Electric Power Applications
Publisher: Electric Power Applications
Additional Information: Copyright for this article belongs to Institution of Electrical Engineers (IEE)
Department/Centre: Division of Electrical Sciences > Electrical Engineering
Date Deposited: 29 Jul 2005
Last Modified: 19 Sep 2010 04:19
URI: http://eprints.iisc.ac.in/id/eprint/3402

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