10-04-2017, 08:01 PM
Abstract
This paper describes the conception and analysis of a unidirectional hybrid three-phase rectifier suitable for mediumand high-power applications. The rectifier is composed of a single-switch diode bridge boost-type rectifier in parallel with a pulsewidth modulation (PWM) three-phase unidirectional boost rectifier. The objective is to obtain a structure capable of providing sinusoidal input currents with low harmonic distortion and dc output voltage regulation. The diode rectifier operates at low frequency and has a higher output power rating. Therefore, the PWM unidirectional rectifier is designed to operate with a small power rating and at a high switching frequency. The total harmonic distortion of the proposed structure varies between 0% and 32%, depending only on the amount of power processed by the PWM three-phase unidirectional rectifier. The rectifier topology conception, principle of operation, control scheme, and simulation and experimental results of a 20-kW laboratory prototype are also presented in this paper. Index Terms High-power application, hybrid rectifier, power factor improvement, pulsewidthmodulation(PWM)unidirectional rectifier.
I. INTRODUCTION
TRADITIONALLY, three-phase ac-to-dc high power conversion is performed by diode or phase-controlled rectifiers. Due to the commutation of these structures at the zero crossing of the current, they are also called line-commutated rectifiers. These rectifiers are robust and present low cost, but draw nonsinusoidal currents or reactive power from the source, which deteriorate the power quality. To compensate for the harmonic distortion generated by the standard diode rectifiers, passive linear filters or power factor correction structures can be employed [1] [3]. The multipulse three-phase rectifiers achieve harmonic cancelation by introducing phase shift by means of special threephase transformers [4], [5]. Moreover, the simplicity and reli- Manuscript received February 28, 2008; revised June 29, 2008 and October 6, 2008. First published February 18, 2009; current version published April 8, 2009. This work was supported in part by the National Council for Scientific and Technological Development (CNPq). Recommended for publication by Associate Editor J. H. R. Enslin. R. L. Alves is with the Power Electronics Institute (INEP), Federal University of Santa Catarina, Florian opolis SC 88040-970, Brazil, and also with the Federal Centre of Technological Education (CEFET-SC), Florian opolis 88020-301, Brazil (e-mail: [email protected]). I. Barbi is with the Power Electronics Institute (INEP), Electrical Engineering Department, Federal University of Santa Catarina, Florian opolis SC 88040-970, Brazil (e-mail: [email protected]). Color versions of one or more of the figures in this paper are available online at http://ieexplore.iee.org. Digital Object Identifier 10.1109/TPEL.2008.2010219 ability of the diode rectifiers are preserved. However, they are heavy, bulky, and expensive. Three-phase pulsewidth modulation (PWM) rectifiers are widely employed in low- and medium-power drive applications where the requirements established by international standards should be satisfied [6] [8]. These structures are the most promising rectifiers from a power quality viewpoint [1] since they can present low harmonic distortion and unity power factor. Recent trends in high-power rectifiers have introduced a new class of three-phase rectifiers, the hybrid rectifiers [2], [13] [15]. The term hybrid rectifier denotes the series and/or parallel connection of a line-commutated rectifier and a selfcommutated converter [2]. The line-commutated rectifier operates at low frequency and has a higher output power rating. The active rectifier is designed to operate with a small power rating and at a high switching frequency. The number of publications in the literature shows that rectifier research is concentrating on self-commutated and hybrid rectifiers. The great challenge is to obtain a rectifier that is as robust, light in weight, simple, and cheap as the passive rectifiers and presents the efficient reduction of input current harmonic content ofPWMrectifiers. This research field has great potential for future applications.
DOWNLOAD FULL REPORT
http://googleurl?sa=t&source=web&cd=1&ve...igo_02.pdf&ei=D7gBTs2mDI_wrQeo35CGAw&usg=AFQjCNHX8ut0sG0kh256lNLef8ZaM0-7fA&sig2=BnfeybQ0ANsp5cRfReYFrQ