• Journal of Power Electronics
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• v.16 no.3
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• pp.1110-1121
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• 2016

The mathematical model of a three phase PWM converter under the stationary αβ reference frame is deduced and constructed based on a Proportional-Resonant (PR) regulator, which can replace trigonometric function calculation, Park transformation, real-time detection of a Phase Locked Loop and feed-forward decoupling with the proposed accurate calculation of the inductance voltage vector. To avoid the parallel resonance of the LCL topology, the active damping method of the proportional capacitor-current feedback is employed. As to current vector error elimination, an optimized PR controller of the inner current loop is proposed with the zero-pole matching (ZPM) and cancellation method to configure the regulator. The impacts on system's characteristics and stability margin caused by the PR controller and control parameter variations in the inner-current loop are analyzed, and the correlations among active damping feedback coefficient, sampling and transport delay, and system robustness have been established. An equivalent model of the inner current loop is studied via the pole-zero locus along with the pole placement method and frequency response characteristics. Then, the parameter values of the control system are chosen according to their decisive roles and performance indicators. Finally, simulation and experimental results obtained while adopting the proposed method illustrated its feasibility and effectiveness, and the inner current loop achieved zero static error tracking with a good dynamic response and steady-state performance.

• Korean journal of applied entomology
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• v.43 no.4 s.137
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• pp.311-315
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• 2004

The brown planthopper, Nilaparvata lugens, is among the most serious insect pests of rice. It is widely distributed in Asia, Australia and Pacific islands. An earlier mitochondrial DNA study revealed that there exist significant genetic differences between populations north and south of the Red River Delta region in Vietnam. However the mitochondrial DNA was not sufficiently variable to examine the sources of immigration. For a more detailed analysis of geographic population structure of N. lugens, we developed microsatellite markers. Thirty-seven putative microsatellite loci were isolated using a magnetic biotin method, and five primer pairs designed from the flanking regions of sequenced microsatellite clones were labeled with fluorescent. Of these five primer sets, two have proven to be useful across all the samples we used in this study. We used variation at these two microsatellite loci to test the hypothesis that N. lugens biotypes (1, 2, and 3) sampled from laboratory selection constituted distinct genetic units. Allele frequency differences among the three major biotype categories were not significantly different at one locus (27035). However, the other (7314) did show differences among the major three biotypes. The methods we describe here will be useful for studying population structure of crop pest and for tracking the patterns of migratory pest like the rice planthoppers.