Analysis and mitigation of dead time harmonics in the single-phase full-bridge PWM converters with repetitive controllers

In order to prevent the power switching devices (e.g., the Insulated-Gate-Bipolar-Transistor, IGBT) from shoot through in voltage source converters during a switching period, the dead time is added either in the hardware driver circuits of the IGBTs or implemented in software in Pulse-Width Modulation (PWM) schemes. Both solutions will contribute to a degradation of the injected current quality. As a consequence, the harmonics induced by the dead time (referred to as "dead time harmonics" hereafter) have to be compensated in order to achieve a satisfactory current quality as required by standards. In this paper, the emission mechanism of dead time harmonics in single-phase PWM inverters is thus presented considering the modulation schemes in details. More importantly, a repetitive controller has been adopted to eliminate the dead time effect in single-phase grid-connected PWM converters. The repetitive controller has been plugged into a proportional resonant-based fundamental current controller so as to mitigate the dead time harmonics and also maintain the control of the fundamental frequency grid current in terms of dynamics. Simulations and experiments are provided, which confirm that the repetitive controller can effectively compensate the dead time harmonics and other low-order distortions, and also it is a simple method without hardware modifications

Mixed-Spin-P fields for GIT quotients

The theory of Mixed-Spin-P (MSP) fields was introduced by Chang-Li-Li-Liu for the quintic threefold, aiming at studying its higher-genus Gromov-Witten invariants. Chang-Guo-Li has successfully applied it to prove conjectures on the higher-genus Gromov-Witten invariants, including the BCOV Feynman rule and Yamaguchi-Yau's polynomiality conjecture. This paper generalizes the MSP fields construction to more general GIT quotients, including global complete intersection Calabi-Yau manifolds in toric varieties. This hopefully provides a geometric platform to effectively compute higher-genus Gromov-Witten invariants for complete intersections in toric varieties. The key to our paper is a stability condition which guarantees the separatedness and properness of the cosection degeneracy locus in the moduli. It also gives a mathematical definitions for more general Landau-Ginzburg theories.Comment: 46 pages, bibliography update

A boundedness theorem for principal bundles on curves

Let $G$ be a reductive group acting on an affine scheme $V$. We study the set of principal $G$-bundles on a smooth projective curve $\mathcal C$ such that the associated $V$-bundle admits a section sending the generic point of $\mathcal C$ into the GIT stable locus $V^{\mathrm{s}}(\theta)$. We show that after fixing the degree of the line bundle induced by the character $\theta$, the set of such principal $G$-bundles is bounded. The statement of our theorem is made slightly more general so that we deduce from it the boundedness for $\epsilon$-stable quasimaps and $\Omega$-stable LG-quasimap.Comment: 16 pages, bibliography update

4-{2-[4-(Dimethyl­amino)­phen­yl]ethen­yl}-1-methyl­pyridinium 2-amino-3,5-dimethyl­benzene­sulfonate monohydrate

In the crystal structure of the title compound, C16H19N2 +·C8H10NO3S−·H2O, the cations and anions are linked by O—H⋯O and N—H⋯O hydrogen bonds, forming alternating layers parallel to the ac plane. An intra­molecular N—H⋯O hydrogen bond occurs in the anion. The crystal structure is further stabilized by π–π inter­actions, with centroid–centroid distances of 3.7240 (9) and 3.6803 (8) Å

A new copper(II) complex based on 1-[(1H-benzotriazol-1-yl)meth­yl]-1H-1,2,4-triazole

The title complex, tetra­aqua­{1-[(1H-benzotriazol-1-yl)meth­yl]-1H-1,2,4-triazole-κN 4}(sulfato-κO)copper(II) sesquihydrate, [Cu(SO4)(C9H8N6)(H2O)4]·1.5H2O, is composed of one copper atom, one 1-[(2H-benzotriazol-1-yl)meth­yl]-1-H-1,2,4-triazole (bmt) ligand, one sulfate ligand, four coordin­ated water mol­ecules and one and a half uncoordinated water mol­ecules. The CuII atom is six-coordinated by one N atom from a bmt ligand and five O atoms from the monodentate sulfate ligand and four water mol­ecules in a distorted octa­hedral geometry. In the crystal, adjacent mol­ecules are linked through O—H⋯O and O—H⋯N hydrogen bonds involving the sulfate anion and the coordin­ated and uncoordinated water mol­ecules into a three-dimensional network