Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
An active voltage doubler utilizing a single supply op-amp for energy harvesting system is presented.The proposed doubler is used\nfor rectification process to achieve both acceptably high power conversion efficiency (PCE) and large rectified DC voltage. The\nincorporated op-amp is self-biased, meaning no external supply is needed but rather it uses part of the harvested energy for its\nbiasing. The proposed active doubler achieves maximum power conversion efficiency (PCE) of 61.7% for a 200Hz sinusoidal input\nof 0.8V for a 20K�© load resistor. This efficiency is 2 times more when compared with the passive voltage doubler.The rectified DC\nvoltage is almost 2 times more than conventional passive doubler.The relation between PCE and the load resistor is also presented.\nThe proposed active voltage doubler is designed and simulated in LF 0.15 ...
This work presents the design, modeling, and implementation of a neural network inverse\nmodel controller for tracking the maximum power point of a photovoltaic (PV) module. A nonlinear\nautoregressive network with exogenous inputs (NARX) was implemented in a serial-parallel\narchitecture. The PV module mathematical modeling was developed, a buck converter was designed\nto operate in the continuous conduction mode with a switching frequency of 20 KHz, and the\ndynamic neural controller was designed using the Neural Network Toolbox from Matlab/Simulink\n(MathWorks, Natick, MA, USA), and it was implemented on an open-hardware Arduino Mega board.\nTo obtain the reference signals for the NARX and determine the 65 W PV module behavior, a system\nmade of a 0.8WPV cell, a temperature sensor, a voltage sensor and a static neural network, was used.\nTo evaluate performance a comparison with the P&O traditional algorithm was done in terms of\nresponse time and oscillations around the operating point. Simulation results demonstrated the\nsuperiority of neural controller over the P&O. Implementation results showed that approximately the\nsame power is obtained with both controllers, but the P&O controller presents oscillations between\n7 W and 10W, in contrast to the inverse controller, which had oscillations between 1 W and 2 W....
Enhancing the performance of the voltage source inverters (VSIs) without changing\nthe hardware structure has recently acquired an increased amount of interest. In this study,\nan optimization algorithm, enhancing the quality of the output power and the efficiency of\nthree-phase grid connected VSIs is proposed. Towards that end, the proposed algorithm varies\nthe switching frequency (fsw) to maintain the best balance between switching losses of the\ninsulated-gate-bipolar-transistor (IGBT) power module as well as the output power quality under\nall loading conditions, including the ambient temperature effect. Since there is a contradiction\nwith these two measures in relation to the switching frequency, the theory of multi-objective\noptimization is employed. The proposed algorithm is executed on the platform of Altera�®\nDE2-115 field-programmable-gate-array (FPGA) in which the optimal value of the switching\nfrequency is determined online without the need for heavy offline calculations and/or lookup\ntables. With adopting the proposed algorithm, there is an improvement in the VSI efficiency without\ndegrading the output power quality. Therefore, the proposed algorithm enhances the lifetime of\nthe IGBT power module because of reduced variations in the moduleâ��s junction temperature. An\nexperimental prototype is built, and experimental tests are conducted for the verification of the\nviability of the proposed algorithm....
It is necessary for three-level explosion-proof inverters to have high thermal stability and good output characteristics avoiding\nproblems caused by power devices, such as IGBT, so it becomes a hot and difficult research point using only one control algorithm\nto guarantee both output characteristics and high thermal stability. Firstly, the simplified SVPWM (Space Vector Pulse Width\nModulation) algorithm was illustrated based on the NPC (neutral-point-clamped) three-level inverter, and then the quasi-square\nwave control was brought in and made into a novel holographic equivalent dual-mode modulation algorithm together with the\nsimplified SVPWM. The holographic equivalent model was established to analyze the relative advantages comparing with the\ntwo single algorithms. Finally, the dynamic output and steady power device losses were analyzed, based on which the power loss\ncalculation and system simulation were conducted as well.The experiment proved that the high-power three-level explosion-proof\ninverter has good output characteristics and thermal stability...
Thetotal ionizing dose irradiation effects are investigated in Si vertical diffusedMOSFETs (VDMOSs) with different gate dielectrics\nincluding single SiO2 layer and double Si3N4/SiO2 layer. Radiation-induced holes trapping is greater for single SiO2 layer than for\ndouble Si3N4/SiO2 layer. Dielectric oxidation temperature dependent TID effects are also studied. Holes trapping induced negative\nthreshold voltage shift is smaller for SiO2 at lower oxidation temperature. Gate bias during irradiation leads to different ...
Loading....