Power Based Phase-Locked Loop Under Adverse Conditions with Moving Average Filter for Single-Phase System

High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL) uses a multiplier as phase detector(PD). As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF) applied in-loop of pPLL. The signal characteristic of phase error is dissussed in detail. A predictive rule is adopted to compensate the delay induced by MAF, thus achieving fast dynamic response. In the case of frequency deviate from nomimal, estimated frequency is fed back to adjust the filter window length of MAF and buffer size of predictive rule. Simulation and experimental results show that proposed PLL achieves good performance under adverse grid conditions

Metal-substitution strategy to control the conductive path in titanium dioxide: ab initio calculations

Revealing the atomic-nature of the conductive path in TiO2 layer based resistive-switching devices still remains a critical challenge. Metal atoms doping in TiO2 layer are always considered as an effective way to improve the electronic properties in resistive random access memory. Efforts to clarify the effects of metal atom substitution on the conductive path in rutile TiO2 have been done by using first-principles calculation. The dependence of the conductive path on the substitution of Ag/Cu/Al/Hf/Ta/V adjacent to the ordering oxygen vacancies or away from them has been studied in detail to elucidate the formation mechanism of conductive path. Theoretical investigation demonstrates that Hf or V substitution where it occurs adjacent to the oxygen vacancies benefits electrons aggregation among Ti-ions. Such electrons aggregation, which is one type of the conductive path in TiO2, will be prompted by Ti-t2g orbital electron. The dependent relation of the conductive path on the substitution of Ag/Cu/Al/Hf/Ta/V will be an important factor to optimize future resistive random access memory

Photonic Design and Electrical Evaluation of Dual-Functional Solar Cells for Energy Conversion and Display Applications

Abstract Colored solar cells (SCs) are highly useful for applications in esthetic building-integrated photovoltaics (BIPVs). However, the theoretical designs mostly focus on the color quality with rarely addressing the optoelectronic responses. Here, considering both color display and complete electrical evaluation, we report a color-controlled a-Si:H SC in purely planar configuration, which simultaneously exhibits the desired high-purity color and sustains a relatively high power conversion efficiency. The high-performance color display is realized by thin-film photonic designs with incorporating distributed Bragg reflector and anti-reflection coating layers. Moreover, a comprehensive optoelectronic simulation addressing both the electromagnetic and internal semiconductor physics has been realized, which shows that the power conversion efficiencies of the designed red-green-blue (RGB) SCs can be 4.88%, 5.58%, and 6.54%, respectively. The physical principles of optimizing the colorful SCs with the tunable hue, high saturation, and brightness are explained, and we take the logo of “Soochow University” as an example to demonstrate the wide-angle pattern display by the SCs. The study paves the way of realizing the colored SCs targeting esthetic BIPV applications

First-principle study on the effects of electric field and anisotropic oxygen vacancy on dielectric properties of rutile titanium dioxide

First principles studies about the influence of electric field and anisotropic oxygen vacancy on the dielectric properties of rutile titanium dioxide (TiO2) are investigated. These results demonstrate that dielectric properties of perfect TiO2 presents dependent on the low electric field that less than 5.2 MV/cm. As a comparison, the dielectric properties of defected TiO2 in (1 1 0) plane and [1 1 0] direction show more sensitive to high electric field. Further more, considering the different positions of oxygen vacancy, the oxygen vacancy locates in (1 1 0) plane of defected TiO2 appears more active to high electric field than it does in [1 1 0] direction. The effect of electric field and oxygen vacancy induce the distorted supercell structure and broken bond between the nearer oxygen atoms and titanium atoms. Moreover, the oxygen vacancy locates in (1 1 0) plane of defected TiO2 can create more potential broken bond. These results account for the difference of dielectric properties in perfect TiO2 and defected TiO2

Nature of the Interstitials in Titanium Dioxide and Their Impact on Transmission Coefficient: Ab Initio Calculations

The ab initio calculations about the properties of the interstitials doping in the rutile TiO2 and their impact on the transport coefficients are reported. As the doping of the Zr or Ti interstitials in the TiO2, the lattice Ti4+ ions acquire the excess electrons so reduced to the Ti3+ or Ti2+ ions. However, the Cu interstitials could not lose enough electrons to reduce the lattice Ti4+ ions. Furthermore, the Ti or Cu interstitials in the ZrO2 also are unable to promote the lattice Zr4+ ions to form the lattice Zr3+ or Zr2+ ions. The high transport coefficients are observed in the defected TiO2 with the Ti or Zr interstitials as the high concentration of the Ti3+ or Ti2+ ions. So, the Zr interstitials are the favorable choice for the extra-doping to improve the transport properties in the TiO2-based resistive random access memory

First-principles study on defected titanium dioxide with the Zr substitution for improved reliability of the conduction path

The improved reliability of the conduction path as the Zr substitution doping in the rutile TiO2 are investigated on the first-principle calculations. The conduction path is easily produced by ordering of double oxygen vacancies in the TiO2/TiO2–x structure rather than in the TiO2–x/TiO2 structure. In the TiO2–x/TiO2 structure, the conduction path is ruptured in the middle under the external electric fields of 20.8 MV/cm. It originates from the internal electric fields strengthened in the middle of the conduction path. The Zr substitutions for the Ti atoms, at the interface of the TiO2–x/TiO2 structure or the TiO2/TiO2–x structure, improve the reliability of the conduction path. In contrast, the doping of Cu substitutions for the Ti atoms at the same regions presents less much to be desired. The phenomenon is attributed to the Zr substitutions impel the larger probability of the electrons to occupy the middle region between the Ti atoms