Abstract
An active current injection network for a three-phaserectifier is proposed. The proposed circuit uses three bidirectionalswitches operating at low frequency and a half-bridge inverteroperating at high frequency. It also uses an inductor in orderto make the current modulation. Because only 3.7% of the totalpower delivered to the load is processed by the injection network,the proposed converter offers high efficiency, and not only a highpower factor is obtained but also the total harmonic distortion isreduced. Operation, analysis, simulation, and experimental resultsare shown in this paper.
Index Terms—Current injection, high power factor, rectifiers,three-phase.
I. INTRODUCTION
THE INCREASE of nonlinear loads to the electric powerdistribution has motivated research for finding differentoptions in order to alleviate the difficulties associated withthe power quality. Diode rectifiers are extensively used; thisis because they are cheap and simple. However, for the threephaserectifier, not only is the power factor penalized, but alsoa current with high harmonic content is required.Different three-phase topologies for ac/dc conversion havebeen proposed in order to obtain a low harmonic content andto increase the power factor [1]–[26]; the current shaping hasbeen extensively used as a good choice in three-phase systems[14]–[26].Three-phase topologies with active current modulation havebeen extensively studied [14]–[21]. These schemes add aconverter which processes all the energy (boost, buck, andbuck–boost), as shown in Fig. 1. The advantage of these topologiesis that a good performance is obtained for various operatingpoints (different output power). However, not only is anexpensive complex controller required, but also the efficiency ispenalized because the power delivered to the load is completelyprocessed by the converter which has been added.In Fig. 1(b) is shown a circuit that considers an extra converterand the injection technique [16]. It is based on the boostconverter; two inductors, two switches, and three bidirectional switches are used. All the power is processed by the step-uptopology, and then, the efficiency is penalized. The controllerrequires sensing the inductor currents, the injected current, andthe output voltage; a sophisticated controller is implemented forthis topology, but low harmonic content at the input current isobtained.Three-phase topologies with passive current modulation havealso been widely studied [22]–[26]; these schemes considera passive network instead of active components, as shown inFig. 2. These converters have the advantage that they do notprocess all the energy delivered to the load. However, hugepassive elements are used (including resistance) because theyoperate at low frequency; moreover, due to the resistive components,the efficiency is also penalized. Because these convertersare tuned for a single operating point, the performance under aload variation or any other different output power is not goodenough.


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