Terms Of Power Factor Research Articles

Thermoelectric properties of n-type cobalt doped chalcopyrite Cu1−xCoxFeS2 and p-type eskebornite CuFeSe2

Chalcopyrite CuFeS2 has been recently suggested as a promising thermoelectric material. In the present paper, the transport properties – electrical resistivity ρ and Seebeck coefficient S – of the n-type CuFeS2 chalcopyrite and the p-type CuFeSe2 eskebornite have been measured. Very different groundstates are evidenced with a semimetallic behavior concomitant to a metal-like S(T) curve for CuFeSe2 whereas CuFeS2 is a semiconductor with much larger |S| values. For that reason, charge creation by Co2+ for Cu+ substitution in CuFeS2 has been performed. The veracity of the Co for Cu substitution for x ≤ 0.10 in Cu1−xCoxFeS2 chalcopyrite has been confirmed by EDS analyses, coupled to electron diffraction, with a transmission electron microscope. Also, this study demonstrates the existence of twinning domains. The compounds corresponding to the best compositions in terms of power factor have been densified by Spark Plasma Sintering for thermal conductivity measurements. A maximum ZT value up to 0.22 at 675 K for Cu0.96Co0.04FeS2 has been obtained.

A Bidirectional High-Power-Quality Grid Interface With a Novel Bidirectional Noninverted Buck–Boost Converter for PHEVs

Plug-in hybrid electric vehicles (PHEVs) will play a vital role in future sustainable transportation systems due to their potential in terms of energy security, decreased environmental impact, improved fuel economy, and better performance. Moreover, new regulations have been established to improve the collective gas mileage, cut greenhouse gas emissions, and reduce dependence on foreign oil. This paper primarily focuses on two major thrust areas of PHEVs. First, it introduces a grid-friendly bidirectional alternating current/direct current ac/dc-dc/ac rectifier/inverter for facilitating vehicle-to-grid (V2G) integration of PHEVs. Second, it presents an integrated bidirectional noninverted buck-boost converter that interfaces the energy storage device of the PHEV to the dc link in both grid-connected and driving modes. The proposed bidirectional converter has minimal grid-level disruptions in terms of power factor and total harmonic distortion, with less switching noise. The integrated bidirectional dc/dc converter assists the grid interface converter to track the charge/discharge power of the PHEV battery. In addition, while driving, the dc/dc converter provides a regulated dc link voltage to the motor drive and captures the braking energy during regenerative braking.

DSP-based current sharing of average current controlled two-cell interleaved boost power factor correction converter

Power factor correction (PFC) pre-regulators are used between the ac line and non-linear load to improve the line current in terms of power factor and total harmonic distortion (THD). In medium- and high-power applications, the interleaved boost PFC converter is the proper solution for this purpose to obtain a pre-regulator with lower size. The operation of the interleaved boost PFC converter provides a reduction of the inductor and electromagnetic interference filter volumes compared with those of the conventional single switch boost PFC converter. However, proper current sharing and current ripple minimisation must be ensured to achieve these benefits. The current sharing between cells of a two-cell interleaved boost PFC converter, which is an important problem in applications is analysed and discussed in this study and the problem is removed by using a digital signal processing (DSP)-based simple practical solution. The proposed technique provides the proper current sharing by sensing only the rectifier output current (total current of cells) without using any external control loop. The simulation and the experimental results are presented to show the validity.

Theoretical Study on Thermoelectric Properties of Ge Nanowires Based on Electronic Band Structures

Theoretical studies on the thermoelectric properties of Ge nanowires (NWs) in terms of the Seebeck coefficient, electrical conductance, and power factor are carried out under different combinations of parameters. As orientation affects power factor, [100] Ge NWs have better performance than NWs along [111] and [110] in general. For extremely small (1-nm) NWs, the effect of cross-sectional shape also plays an important role on the thermoelectric properties of Ge NWs due to quantum confinement effects. The thermoelectric properties vary strongly depending on the band structure of the Ge NWs of different sizes, cross-sectional shapes, and orientations. Comparing the results between 1-nm triangular Ge and Si NWs in terms of power factor, p-type Ge NWs outperform Si NWs, while n-type Si NWs outperform Ge NWs due to the higher numbers of subband valleys contributing to electron transport.

CLOSED LOOP CONTROLLED SERIES RESONANT PFC DC TO DC CONVERTER

The aim of this work is to simulate closed loop controlled Series Resonant PFC DC – DC converter using Matlab Simulink. The quality of power consumption in terms of power factor and electromagnetic interference (EMI) levels are becoming one of the most important aspects in the design of static power converters. A model for closed loop controlled DC – DC series resonant PFC converter has been developed and it is used to perform simulation studies.

Geometry effects on thermoelectric properties of silicon nanowires based on electronic band structures

The thermoelectric properties of silicon nanowires with different shapes, sizes, and orientations are theoretically investigated using sp3d5s∗ tight-binding model coupled with ballistic transport approach. We found that the thermoelectric properties significantly depend on nanowire geometry. Compared to [111] and [100] nanowires, n-doped and p-doped [110] nanowires show the worst performance in terms of power factor per cross-section area and figure of merit (ZT). As nanowire size decreases, thermoelectric properties of nanowires can be enhanced. As a result, triangular nanowires with side length of 1 nm have the best results of ZT and it can be enhanced to 1.5 and 0.85 for an n-type nanowire along [111] orientation and a p-type nanowire along [100] orientation, respectively. For extremely narrow nanowires, thermoelectric properties are only dependent on the number of the transmission modes instead of material properties such as carrier effective mass. Moreover, cross-section shape and thermal conductance contributed by electrons play important roles in ZT while their influence can be ignored for large size nanowires. Even though smaller size nanowires have better performance with the consideration of the single nanowire thermoelectric properties, they might be less efficient than larger diameter nanowires, as packing space is not very dense.

Training and optimization of an artificial neural network controlling a hybrid power filter

A hybrid power compensator (HPC) consisting of a static VAr compensator and a dynamic compensator needs to be optimally controlled during the compensation of nonlinear loads. The HPC must be controlled to meet minimum requirements in terms of power factor and harmonic distortion, while at the same time minimizing its total cost. An artificial neural network (ANN) is used to control the HPC amidst a very dynamic power system environment. The performance of a reference ANN is evaluated while controlling an HPC connected to a typical nonlinear industrial load. The training and performance of the ANN is then optimized in terms of training set size, training set packing and ANN topology and the performance compared to the reference ANN. This paper highlights the importance of optimising the mentioned ANN parameters to achieve optimum ANN training and modeling accuracy. The results obtained reveals that the application of an ANN in controlling an HPC is feasible given that the ANN parameters are chosen appropriately.

Optimal control of a hybrid power compensator using an artificial neural network controller

A hybrid power compensator (HPC) consisting of a static VAr compensator and a dynamic compensator needs to be optimally controlled during the compensation of nonlinear loads. The HPC must be controlled to meet minimum requirements in terms of power factor and harmonic distortion, while at the same time minimizing its total cost. The use of an artificial neural network (ANN) to control the HPC amid a very dynamic environment to achieve the above is investigated. A state-space model of the power distribution network together with the HPC forms the basis of evaluation of the mentioned controller. The model was calibrated against actual in-network measurements. The results obtained reveals that the application of an ANN in controlling an HPC is feasible given that the ANN parameters are chosen appropriately.

Evaluation of the adaptive behaviour of an artificial neural network controller for a hybrid power compensator

AbstractAn artificial neural network (ANN) is used to optimally control a hybrid power compensator (HPC) consisting of a static VAR compensator (SVC) and a dynamic compensator (DC) during the compensation of nonlinear loads. The HPC must be controlled to meet minimum requirements in terms of power factor and harmonic distortion, while at the same time minimising its total cost. The ability of the ANN to adapt its output when subjected to a dynamic power system environment to achieve the above, is evaluated. The power system dynamics in this paper constitute line impedance changes and changes in the load conditions of other consumers coupled to the same network. A state space model of the power distribution network together with the HPC forms the basis of evaluation of the mentioned controller. The results obtained reveal that the ANN can meaningfully adapt its output to optimise the HPC performance.

A performance comparison of PWM rectifiers and synchronous link converters

PWM AC/DC power converters have been shown to be superior to thyristor phase-controlled rectifiers in terms of power factor and input current/output voltage harmonics. This paper presents a systematic comparison of the two topologies, the current-source topology and the voltage-source topology, from the point of view of power converter and switch kVA ratings, filtering requirements, power factor, operating regions, and control aspects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>