CD Home Nanogrid: Avoiding Standby Consumption and Diminishing Ripple Amplitudes

<div>The nanogrids are the basic unit to develop more complex and stronger distributed systems. DC nanogrids allow a better performance and higher efficiency than the AC nanogrids. The lack of DC home appliances in the local market has resulted in a slow development of DC Home Nanogrids (DCHN). The Compact Fluorescent Lamp (CFL) and LED are used in power electronics as high efficiency and low cost lightning components. However, these devices represent a source of emission of harmonics in Alternating Current (AC) and Direct Current (DC) systems, due to their nonlinear behavior. In this paper a mathematical model for the nonlinear loads and experimental results of the voltage and current ripple in a DCHN are presented. The CFL and LED lamps are used as our nonlinear loads for test the model. The model explains well the experimental results of how the ripple amplitude is reduced. We also present the effect of decreasing the ripple amplitude when it is incorporated an induction stove in standby mode to the DCHN, which also is explained by the model.</div>

CD Home Nanogrid: Avoiding Standby Consumption and Diminishing Ripple Amplitudes

<div>The nanogrids are the basic unit to develop more complex and stronger distributed systems. DC nanogrids allow a better performance and higher efficiency than the AC nanogrids. The lack of DC home appliances in the local market has resulted in a slow development of DC Home Nanogrids (DCHN). The Compact Fluorescent Lamp (CFL) and LED are used in power electronics as high efficiency and low cost lightning components. However, these devices represent a source of emission of harmonics in Alternating Current (AC) and Direct Current (DC) systems, due to their nonlinear behavior. In this paper a mathematical model for the nonlinear loads and experimental results of the voltage and current ripple in a DCHN are presented. The CFL and LED lamps are used as our nonlinear loads for test the model. The model explains well the experimental results of how the ripple amplitude is reduced. We also present the effect of decreasing the ripple amplitude when it is incorporated an induction stove in standby mode to the DCHN, which also is explained by the model.</div>

Prodromal dysfunction of α5GABA-A receptor modulated hippocampal ripples in Alzheimer′s disease

Decades of research attempting to slow the onset of Alzheimer′s disease (AD) indicates that a better understanding of memory will be key to the discovery of effective therapeutic approaches. Here, we ask whether prodromal neural network dysfunction might occur in the hippocampal trisynaptic circuit by using α5IA as a selective negative modulator of extrasynaptic α5GABA-A receptors in TgF344-AD transgenic rats, a model for early onset AD. The results demonstrate that orally bioavailable α5IA, an established memory enhancer, increases CA1 pyramidal cell mean firing rates and peak CA1 ripple amplitude during wakeful immobility in wild type F344 rats resting in a familiar environment. We show that TgF344-AD rats, which express human amyloid-beta precursor protein (with the Swedish mutation) and human presenilin-1 (with a Δ exon 9 mutation), exhibit high serum Aβ42 and Aβ40 levels by 3 months of age. By 9 months of age, CA1 ripples in young adult TgF344-AD rats are nonresponsive to α5IA indicating network dysfunction prior to the onset of AD pathology and memory dysfunction. These results demonstrate, to the best of our knowledge, the first evidence for prodromal α5GABA-A receptor dysfunction in the AD hippocampal trisynaptic circuit. Moreover, as α5GABA-A receptors are located extrasynaptically and subserve the function of tonic inhibition we posit that an early stage of memory dysfunction involves the disruption of tonic inhibition in the hippocampus.

Three-Phase and Five-Phase Motor Windings Common Point Potential Ripple with Respect to the Converter Zero Termina

The aim of the study is to determine the parameters characterizing the ripple of a motor's three- and five-phase windings common point potentials (for the star winding connection diagram) with respect to the converter zero point. One of the reserves for decreasing electromagnetically induced vibration of an electric motor with a rotating field is to increase the number of working winding phases. The study subject is a five-phase motor winding connected to a bridge converter, namely, its ability to reduce electromagnetically induced vibration in comparison with that in using a three-phase winding. The common point potential ripple parameters are studied, and an approach is proposed to estimating the amplitude modulation of the space-time voltage vector of three- and five-phase windings under the influence of the common point potential ripple with respect to the converter zero point. Theoretical studies were carried out using the Fourier series expansion method and vector analysis methods. To confirm the theoretical results, experimental studies of the prototypes of three-phase and five-phase synchronous motors with inductors made on the basis of permanent magnets were carried out. The main results have shown the following. With increasing the number of phases of the rotating field motor working winding connected to a bridge converter, the common point potential ripple amplitude with respect to the converter zero point decreases, and the ripple frequency increases. The product of ripple amplitude by frequency remains unchanged. It is assumed that the common point potential ripple of the motor multiphase winding with respect to the converter zero terminal results in the amplitude modulation of the space-time voltage vector. With increasing the number of winding phases, the modulation amplitude decreases, and the modulation frequency increases. A five-phase motor has a lower level of the working winding common point potential ripple with respect to the converter zero point in comparison with a three-phase motor. Thus, it can be assumed that there will be a lower level of electromagnetically induced vibration in using a simple converter operation algorithm. The obtained results can be used in designing electric traction systems with vector control on the basis of multiphase motors. With increasing the number of phases, the common point potential ripple amplitude in a multiphase winding with respect to the converter zero point decreases, and the ripple frequency increases. Thus, the common point potential ripple amplitude in a five-phase winding is 5/3 times less than that in a three-phase winding, and the ripple frequency increases by 5/3 times, respectively. With increasing the number of working winding phases, the amplitude modulation of the resulting space-time voltage vector decreases. This circumstance has a positive effect on decreasing the electromagnetically induced vibration.

Relativistic self-focusing in the interaction of laser beam and plasma with periodical density ripple

In the paper, relativistic self-focusing in the interaction of laser beam and plasma with periodical density ripple has been studied by the applied WKB approximation and higher-order paraxial theory. The result shows that under the influence of relativistic nonlinear effect, the dielectric function shows the fierce oscillational variation with similar periodicity, which then leads to the intense relativistic beam self-focusing along the propagation distance, such self-focusing also presents similar periodic variation. Besides, in the plasma with periodical density ripple, the initial density and the density ripple amplitude have obvious influence on self-focusing. When the two factors increase, then there will be more strength self-focusing. Choosing the appropriate initial density and the periodic density parameter is benefit to the formation of the more stable self-focusing.

Analysis and Comparison of DC-DC Boost Converter and Interleaved DC-DC Boost Converter

The step-up converters are widespread use in many applications, including powered vehicles, photovoltaic systems, continuous power supplies, and fuel cell systems. The reliability, quality, maintainability, and reduction in size are the important requirements in the energy conversion process. Interleaving method is one of advisable solution for heavy-performance applications, its harmonious in circuit design by paralleling two or more identical converters. This paper investigates the comparison performance of a two-phase interleaved boost converter with the traditional boost converter. The investigation of validation performance was introduced through steady-state analysis and operation. The operation modes and mathematical analysis are presented. The interleaved boost converter improves low-voltage stress across the switches, low-input current ripple also improving the efficiency compared with a traditional boost converter. To validate the performance in terms of input and output ripple and values, the two converters were tested using MATLAB/SIMULINK. The results supported the mathematical analysis. The cancelation of ripple in input and output voltage is significantly detected. The ripple amplitude is reducing in IBC comparing with a traditional boost converter, and the ripple frequency is doubled. This tends to reduce output filter losses, and size.

Optimization of the interference parameters of an Orbit motor using genetic algorithm

In the present study, the leakage of fluid due to gap generation at the contact points is eliminated by introducing interference between the rotor and the stator of an Orbit motor. Interference is incorporated in the system by modifying the roller radius, the chordal thickness, and the pitch circle radius. In an Orbit motor of interference-fit type, the contact points and the rotor center deviate from their original positions as found in an Orbit motor of perfect-fit type. A corrective technique based on minimization of the potential energy of the system is used to obtain the rotor center of an interference-fit motor. The rotor profile is initially generated around the geometrically obtained center of a perfect-fit motor. It is then shifted in the direction of decreasing potential energy, until the rotor center corresponding to minimum energy is attained. The main drawback of introducing interference is the generation of an unbalanced torque which affects the output torque of the motor. Thus, optimization of interference parameters using genetic algorithm is carried out to determine a system for which no gap is generated at the contacts and simultaneously it is ensured that the unbalanced torque ripple amplitude is minimum.

Gelombang listrik amplitudu tinggi dan variasi frekwensi ripple untuk untuk mempercepat pemuatan charger aki basah

Ripel pada tegangan dan arus DC dihindari pada kebanyakan beban-beban DC, karena dapat menambah energi yang tidak perlu. Baterai adalah beban DC, saat aki dalam kondisi diisi oleh charger. Pengisian muatan listrik pada aki memerlukan waktu sampai penuh. kami me-neliti sejauh mana pengaruh amplitudu ripel terhadap kecepatan pe-ngisian penuh pada aki pada frekwensi ripel 100 Hz. Tanda bahwa aki sudah bermuatan penuh, ketika arus beban (I2) sangat kecil atau bahkan mendekati nol. Pada ripel rendah, memerlukan waktu yang lebih panjang, menurut yang ada di penelitian ini pada detik ke 3000, arus I2 masih belum mencapai angka nol. Pada ripel sangat tinggi tinggi, pada detik ke ke 160 arus I2 sdh mencapai mencapai Nol de-ngan lembah negatip. Dapat disimpulkan bahwa riak sangat berpe-ngaruh untuk mengurangi waktu pengisian. Metode penelitian ini, mendesain: rangkaian konverter dc-dc, amplitudu ripple, rangkaian ekivalen baterai, mensimulasi dengan software PSIM, analisis, dan simpulan. Ripple on DC voltage and current is avoided at most DC loads, because it can add unnecessary energy. The battery is a DC load, when the battery is charged by the charger. Charging an electric charge on the battery takes time to full. we investigated the effect of ripel amplitude on the speed of full charge on the battery at 100 Hz ripple frequency. Sign that the battery is fully charged, when the load current (I2) is very small or even close to zero. At low ripel, requires a longer time, according to what is in this study at 3000 seconds, the current I2 still has not reached zero. At a very high ripel, at 160 seconds the current I2 reaches zero with the negative valley. It can be concluded that the ripple is very influential to reduce the charging time. This research method, design: dc-dc converter circuit, ripple amplitude, battery equivalent circuit, simulates with PSIM software, analysis, and conclusions.

Circuit Topology Analysis for LED Lighting and its Formulation Development

Light emitted diode (LED) is becoming more popular in the illumination field, and the design of LED lighting is generally made to provide illumination at lower power usage, helping save energy. A power electronic converter is needed to provide the power conversion for these LEDs to meet high efficiency, reduce components, and have low voltage ripple magnitude. The power supply for LED is revisited in this paper. The LEDs connected in series with diode, transistor, or inductor paths are examined. The formulation for each of the cases is described, including the classical converters of buck, boost, buck–boost, and Ćuk. The circuit reductions of the classic circuit, circuit without the capacitor, and without a freewheeling diode are studied. Using LED to replace freewheeling diodes is proposed for circuit component reduction. General equations for different connection paths have been developed. The efficiency and output ripple amplitude of the proposed power converters are investigated. Analytical study shows that the efficiency of proposed circuits can be high and voltage ripple magnitude of proposed circuits can be low. The results show that the proposed circuit topologies can be easily adapted to design LED lighting, which can meet the criteria of high efficiency, minimum components, and low-voltage ripple magnitude at the same time.

Analysis of Equivalent Inductance of Three-phase Induction Motors in the Switching Frequency Range

The equivalent inductance of three-phase induction motors is experimentally investigated in this paper, with particular reference to the frequency range from 1 kHz to 20 kHz, typical for the switching frequency in inverter-fed electrical drives. The equivalent inductance is a basic parameter when determining the inverter-motor current distortion introduced by switching modulation, such as rms of current ripple, peak-to-peak current ripple amplitude, total harmonic distortion (THD), and synthesis of the optimal PWM strategy to minimize the THD itself. In case of squirrel-cage rotors, the experimental evidence shows that the equivalent inductance cannot be considered constant in the frequency range up to 20 kHz, and it considerably differs from the value measured at 50 Hz. This frequency-dependent behaviour can be justified mainly by the skin effect in rotor bars affecting the rotor leakage inductance in the considered frequency range. Experimental results are presented for a set of squirrel-cage induction motors with different rated power and one wound-rotor motor in order to emphasize the aforesaid phenomenon. The measurements were carried out by a three-phase sinusoidal generator with the maximum operating frequency of 5 kHz and a voltage source inverter operating in the six-step mode with the frequency up to 20 kHz.