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This paper proposes a transformerless shunt hybrid filter for harmonic compensation of a three-phase six-pulse diode rectifier, where the AC line-to-line voltage is 3.3 or 6.6 kV. The hybrid filter consists of a single tuned LC filter per phase and an active filter with a DC capacitor voltage as low as 300 or 600 V. The two filters are directly connected in series with each other without a transformer. The passive filter absorbs harmonic currents produced by the rectifier, whereas the active filter improves the filtering characteristics of the passive filter. The required rating of the active filter is much smaller than that of a conventional shunt active filter used alone. Another advantage is that no additional switching-ripple filter is required for the active filter because the LC filter acts not only as a tuned LC filter around the seventh-harmonic frequency but also as a switching-ripple filter around 10 kHz. A feedforward control scheme is also proposed to improve the active filter performance. Experimental results obtained from a 200-V, 5-kW laboratory system and simulation results of a 3.3-kV, 300-kW system confirm the validity and effectiveness of the system. The hybrid filter gives satisfactory compensation performance, thus allowing us to put it into practical use. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(2): 54–65, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10236 [ABSTRACT FROM AUTHOR]

PACE4 (paired basic amino acid cleaving enzyme) is a member of a family of the mammalian kexin-like proprotein convertases containing a subtilisin-like catalytic domain. Previously we reported seven isoform mRNAs of PACE4 that vary in size and 3′-coding sequence [A. Tsuji et al. (1994) Biochem. Biophys. Res. Commun. 200, 943–950; K. Mori et al. (1997) J. Biochem. 121, 941–948]. To determine the origin of these isoforms, the entire human PACE4 gene has been isolated as a set of overlapping genomic DNA fragments, and analyzed by restriction enzyme digestion and nucleotide sequence determination. The human PACE4 gene spans at least 250 kb and is distributed over 25 exons that range in size from 39 to 1,422 base pairs. Human PACE4 gene is the largest kexin-like proprotein convertase gene reported to date. The most striking feature of its genomic structure is the size of the introns and the number of exons, although the general organization of signal peptide, propeptide, and catalytic domains, which are conserved in this family, is very similar to that reported for other kexin-like protease genes. The structural analysis of PACE4 genomic DNA indicates that multiple PACE4 transcripts are produced as a consequence of alternative RNA splicing events, including exon skipping, and differences in the usage of the inner 5′-splicing donor and polyadenylation sites. A major transcriptional start site was detected 314 bp upstream from the ATG translational start site by primer extension analysis. Sequence analysis of the 5′ -flanking region revealed that PACE4 gene lacks TATA and CCAAT boxes in the proximal upstream region of the start site, although potential binding sites for several transcription factors including SP1, AP1, AP2, PEA3, Ets-1, GHF (growth hormone factor)-1, CREB (cyclic AMP response element binding protein), and basic helix-loop-helix proteins, were present. An unusual sequence of six tandem repeats of a nonadecamer (GGCCTGGGGGTTCACCTGC) containing an E box is found in the 5′ -flanking region. These results suggest that PACE4 is not a constitutive gene product and its expression is regulated by various transcription factors. [ABSTRACT FROM AUTHOR]