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This research work emphasizes proposing a hybrid social grouping algorithm (SGA) and perturb and observe (P&O) scheme for tracking the global power peak in a partially shaded photovoltaic (PV) array. PV panels getting shaded, even partially, exhibits multiple power peaks, and hence conventional maximum power point tracking (MPPT) algorithms fail in tracking the maximum power peak as it gets deceived by local maxima. Most of the prevailing global search algorithms suffer in performance due to the stochastic search which consumes time even after nearing the global power peak. Therefore, a hybridization of the global search algorithm and the conventional algorithm will be a prudent solution. SGA, a global search algorithm based on individual and group cognizant behaviour, has been hybridized with a well-entrenched P&O algorithm that complements each other in achieving the global power peak swiftly. The hybridized algorithm achieves the global power peak in 0.4 seconds faster than the stand-alone SGA algorithm during complex shading conditions. The proposed scheme has been implemented for an 800 W PV array in a MATLAB simulation and validated experimentally in a hardware setup using a SAS1000L solar array simulator-programmable source, a DC-DC converter, and a dSPACE 1104 controller. The simulation and experimental results reveal that the proposed search scheme is very competent in converging towards the global maximum through SGA first and achieving the peak point through P&O. The proposed scheme has also been tested for a dynamic shading pattern, and it is evident that the proposed scheme outperforms its counterparts in terms of convergence time. [ABSTRACT FROM AUTHOR]

The conventional heating system is inefficient as the major part of the heating coil lies out-side the vessel it is placed on. This research article proposes a new single-coil multi-tapped induction heating system. This novel induction heating system is facilitated by a half-bridge resonant converter controlled by zero-voltage switching (ZVS). The multi-tapping winding system ensures an effective heat transfer between the coil and the working vessel with the windings of the induction coil segmented to an equivalent size of the vessel. The pulse density modulation (PDM) scheme employed here as the control proves to be the most versatile one. The whole system is duly simulated for an 850 W IH setup in MATLAB Simulink and implemented as a hardware prototype using a half-bridge resonant converter. The control pulses are developed through the PDM in a PIC16F877A controller. The simulation and experimental results prove the credibility of the proposed induction heating (IH) scheme, and during heavy loading conditions, it outperforms the single-coil IH system by gaining an efficiency of 89.29% [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) systems-based energy generation is relatively easy to install, even at a large scale, because it is scalable in size and is thus easy to transport. Harnessing maximum power is only possible if maximum power tracking (MPPT) functionality is available as part of the power converter control that interfaces the PV panels to the grid. Solar exposure covering all PV panels is unlikely to happen all the time, which is known as a partial shading (PS) phenomenon. As a result, depending on the MPPT algorithm adopted, it may fail to find a maximum global power peak, being locked into a local power peak. This research work discusses an alternative MPPT control technique inspired in the social group optimization (SGO) algorithm. SGO belongs to the meta-heuristic optimization techniques family. In this sense, the SGO method ability for solving global optimization problems is explored to find the global maximum power point (GMPP) under the presence of local MPPs. The introduced SGO–MPPT was subjected to different PS conditions and complex shading patterns. Then, its performance was compared to other global search MPPT techniques, which include particle swarm optimization (PSO), the dragon fly algorithm (DFO) and the artificial bee colony algorithm (ABC). The simulation outcomes for the SGO–MPPT characterization showed good results, namely rapid global power tracking in less than 0.2 s with reduced oscillation; the efficiency of solar energy harness was slightly above 99%. [ABSTRACT FROM AUTHOR]

This article presents the aging characterization and modeling of lithium iron phosphate (LiFePO4) batteries. The research work suggested here aims to characterize the aging of the resistances and the capacities of the batteries as a function of using temperature and direct current undulations. The proposed model of the LiFePO4 batteries is for multisource systems, such as distributed power generation systems-based renewable energies. The performances of the batteries used in these systems can be affected by the temperature and the dc-current undulations. The characterization system takes into account the temperature and the dc-current undulations as thermal and electric constraints for batteries. The experimental tests are performed through charging and discharging operations using calibrated fluctuating dc-current waveforms. The experimental measurements and simulations results obtained are similar with a deviation less than 1%. Hence, the proposed model is very appropriate to predict the degradation of battery parameters caused by the combined impacts of direct current undulations and the temperature. [ABSTRACT FROM AUTHOR]

Summary: The concept of induction heating is slowly entrenching as it has the traits of homogeneous heating, zero pollution and higher power density. To achieve these traits convincingly in reality, there is a need to develop energy efficient converter topologies, which aid in achieving power regulation of soft switching and very high frequency operation. This paper presents the salient features of converter topologies used for domestic and industrial heating applications with a focus on its stage‐wise power conversion, power density, load handling capacity, soft switching, reliability and size. The performance of these topologies is analysed in terms of converter switching frequency, power rating, modulation techniques, flicker, user performance and efficiency. Moreover, this review paper predicts the future trends associated with the adaptation of wide band‐gap power semiconductor materials, multi‐output topologies, variable frequency control scheme with minimum losses and filter design to improve source‐side power factor. The detailed technology review will be extremely useful for researchers, designers and engineers in choosing the appropriate topology for the chosen application. [ABSTRACT FROM AUTHOR]

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Single switch inverter is a prevalently used topology for domestic induction heating (IH) applications because of its crisp structure, high efficiency and low cost. The inherent issue with this single switch topology is that it has to withstand the whole power of the load and the huge resonating voltage due to the load current during the energy transfer by the capacitor. This process in due course will reduce the performance and also the life of the system. The cumulative stress on the switch due to dynamic variations in AC mains will cause thermal runaway on the switch. Also, this nonlinear operation at the load results in input current distortions. In this work, a simple voltage-limiting control is proposed to reduce the voltage stress of the switch and to maintain a high power factor. The control circuitry and its logic are verified for 500- W IH prototype. The test results reveal that the suggested scheme is simple and efficient in mitigating voltage stress as well. [ABSTRACT FROM AUTHOR]

For many important network types, physical coordinate systems and physical distances are either difficult to discern or inapplicable. Accordingly, coordinate systems and characterizations based on hop-distance measurements, such as Topology Preserving Maps (TPMs) and Virtual-Coordinate (VC) systems are attractive alternatives to geographic coordinates for many network algorithms. We present an approach to recover geometric and topological properties of a network with a small set of distance measurements. The approach is a combination of shortest path (often called geodesic) recovery concepts and low-rank matrix completion, generalized to the case of hop-distances in graphs. Results for sensor networks embedded in 2-D and 3-D spaces as well as for social networks indicate that the method can accurately capture the network connectivity with a small set of measurements. TPM generation can now be based on various context appropriate measurements or VC systems instead of distances to a set of global anchors. The proposed method is a significant generalization that allows the topology to be extracted from a random set of graph shortest paths, making it applicable in contexts such as social networks where VC generation may not be possible. [ABSTRACT FROM AUTHOR]

Micro deep drawing of metallic cups is a cost effective technique if the parameters are suitably identified, but reducing dimensions increases the difficulties in manufacturing. In this work, formability study of pure copper foils and thickness distribution in micro deep drawing are carried out. The pure copper C1100 foil thickness of 100, 200 and 300 µm is selected and the limit drawing ratio is determined. In order to determine the forming depth in micro scale and force required in formed parts, a micro deep drawing tool assembly is developed. The results shows that 300 μm foil exhibits good formability in tensile test and Ericson cupping test. The excessive reduction in thickness specifically at the cup shoulder corner and the upper part of the side wall is located. The thinning is identified maximum at the side wall of the cup along the transverse direction. The results indicate that copper micro cups with high quality can be efficiently produced with appropriate forming parameters. [ABSTRACT FROM AUTHOR]

Induction heating (IH) applications aided by power electronic control system have become very attractive in the recent past. The power electronics circuits succumb to severe switching loss, lower power density if proper switching methodology is not adhered. A state of uncertainty is indispensable in IH application as the power required by the load varies depending upon the nature of work piece. This uncertain issue makes the selection of the control algorithm and controller very vital. The mundane controllers may not be compatible to combat the uncertainties and leads to exhibit dynamic problems say transients, peak overshoot and poor response. Henceforth, the IH system requires a superlative converter topology and control scheme in order to have reduced switching loss and to improve the system performance there by negating the uncertainties. Here, in this work, a direct AC–AC boost resonant converter fed by pulse density modulation (PDM) is realized in a single stage mode. A fuzzy logic-based PDM control technique improves the efficiency and provides the versatile power control with reduced time domain specifications for dynamic changes in load. The proposed system has been studied using MATLAB/SIMULINK and validated using a hardware prototype employing dsPIC30F4011 microcontroller. The results reveal that efficient control over power can be accomplished by varying the density of the switching pulses, and thereby the efficiency is enhanced even with reduced component count. Also, the single-stage conversion is effective than its two-stage counterpart. [ABSTRACT FROM AUTHOR]

The efficiency of photovoltaic (PV) power system is hampered to a large extent when it is shaded even by a fraction. The performance dwindle in PV array due to partial shading is not proportional to the volume of shading, rather it depends on pattern of shading, array configuration, and site where PV panels are installed. Total cross-tied (TCT) is the proven scheme among all the prevailing interconnection schemes like series, parallel, series-parallel (SP), and bridge linked to negate partial shading impact. This work aims at proposing a new adaptive algorithm to reconfigure the PV array such that it evades the shading effect. Also, it suggests a unique PV panel arrangement for a familiar shading pattern by which the shading prospects are reduced considerably. The proposed work has a clear edge over the TCT method in managing shading, ruling out multiple peaks in output power curve. This technique is highly recommended for constant power loads as the output current is maintained constant, setting aside the varying atmospheric conditions, whereas other reconfiguring techniques do not address this application. The suggested topology is simulated in matlab/Simscape environment for a 3 × 3 PV array and realized in a hardware prototype where a digital signal controller Dspic30f4011 is used to impart the proposed control algorithm. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The main aim of this study is to amend the maximum power point tracking (MPPT) for the photo voltaic (PV) array when it suffers from partially shaded conditions. When a photo voltaic panel is shaded for a fraction of time, the power output reduces invariably. During partially shaded conditions the power-voltage curves exhibit multiple maxima which makes the conventional MPPT techniques (perturb and observe, incremental conductance etc.) to get trapped in the local maxima. This paper proposes a Differential Evolution (DE) curdled algorithm to track the global maximum power point thereby increasing the performance of PV array and acquiring a better maxima point. The proposed algorithm is realized in MATLAB/Simulink environment. The credibility of the algorithm is ensured by comparing the results of DE algorithm with its well entrenched counterparts Particle Swarm Optimisation (PSO) MPPT technique and Ant Colony Algorithm (ACO). Also this study proves that the suggested technique would prevail over the most prominent Perturb and Observe (P&O) MPPT when the PV array is under shading conditions. [ABSTRACT FROM AUTHOR]

Induction heating (IH) is a process of heating the electrically conducting materials especially ferromagnetic materials with the help of electromagnetic induction through generating heat in an object by eddy currents. A well-entrenched way of IH is to design a heating system pertaining to the usage of ferromagnetic materials such as stainless steel, iron, etc., which restricts the end user's choice of using utensils made of ferromagnetic only. This research article proposes a new scheme of induction heating that is equally effective for heating ferromagnetic and non-ferromagnetic materials such as aluminium and copper. This is achieved by having a competent IH system that embodies a series resonant inverter and controller where a competent flexible load modulation (FLM) is deployed. FLM facilitates change in operating frequency in accordance with the type of material chosen for heating. The recent attempts by researchers on all metal IH have not addressed much on the variable shapes and sizes of the material, whereas this research attempts to address that issue as well. The proposed induction heating system is verified for a 2 kW system and is compatible with both industrial and domestic applications. [ABSTRACT FROM AUTHOR]

The output of a photovoltaic array is reduced considerably when PV panels are shaded even partially. The impact of shading causes an appreciable loss in power delivery, since the PV panels are connected in series and parallel to contribute to the required voltage and power for the load. The prevailing research on mitigating the shading impact is mostly based on complex reconfiguration strategies where the PV panels are subjected to complex rewiring schemes. On the other hand, to disperse the shading many studies in the literature defend the physical rearrangement of the panels. The available intensive reconfiguration schemes, such as the series parallel (SP), bridge link (BL), honeycomb (HC), and total cross tied (TCT) schemes, try only to mitigate the shading impact and there is no scope for compensation; as a result, a loss of output power is inevitable. In the proposed research work, both the mitigation of and the compensation for the losses incurred due to shading are studied. In this work, an optimal reconfiguration scheme is adopted to reduce the shading impact and a power electronic circuit with a battery source is designed to compensate for the shading losses in all aspects. In the optimal reconfiguration scheme, a bifurcation strategy is adopted in each column and the electrical connections of the PV panels are interchanged such that the shading impact is dispersed. The power electronic circuit consists of a half-bridge buck converter with a battery source that injects the current required by a shaded column. This setup compensates for the shaded PV array's power and improves the efficiency of the total system. The proposed scheme was implemented in a 3200 W system and subjected to various shading patterns, including single panel shading, corner shading, long and wide shading, and random shading. The proposed scheme was simulated in the MATLAB Simulink environment and compared with static 4 × 4 PV array configurations, including the series parallel (SP), bridge link (BL), honeycomb (HC), and total cross tied (TCT) configurations. The comparative performance was assessed in terms of mismatch power loss, fill factor, and efficiency. The proposed system is suitable for all shading patterns and was proved to be very efficient even in the worst shading, where 1353 W was saved. [ABSTRACT FROM AUTHOR]

Discusses the use of a graphical windows based software tool called the GUI Software to protect computer systems. How the tool was developed; Components of this software package; Description of software tool.

This paper proposes a three-port Zeta-KY dc-dc converter which is fed with hybrid sources like photovoltaic (PV) cells and batteries. The converter proposed here is a multi-input single-output (MISO) structure which harnesses the benefits of Zeta and KY converters. The combination of these converters is highly advantageous since the Zeta converter provides lesser output voltage ripples with high gain and the KY converter topology suits well for withstanding load transients. The KY converter used in this research work is subjected to a topological change to facilitate bidirectional power flow. The bidirectional flow is essential to save the excess power in PV source in batteries during low load conditions. This novel multiport topology with bidirectional facility is first of its kind and has not been discussed earlier in the research arena. In the proposed work, two control algorithms are developed and deployed: the first one ensures the maximum power extraction from the PV and the second one maintains constant dc bus voltage and manages bidirectional power flow. MATLAB Simulink and hardware prototype of the proposed system has been realized for a 72 V dc bus and a 500 W electric vehicular drive. The simulation and experimental results reveal that the proposed system is viable for medium power electric shuttle applications. The proposed system is subjected to various test cases and it is observed that the source and load intermittencies are catered very well by the proposed three port Zeta-KY converter. The developed multiport converter is feasible for renewable energy applications. [ABSTRACT FROM AUTHOR]

The existing solutions for reducing total harmonic distortion (THD) using different control algorithms in shunt active power filters (SAPFs) are complex. This work proposes a split source inverter (SSI)-based SAPF for improving the power quality in a nonlinear load system. The advantage of the SSI topology is that it is of a single stage boost inverter with an inductor and capacitor where the conventional two stages with an intermediate DC-DC conversion stage is discarded. This research proposes inventive control schemes for SAPF having two control loops; the outer control loop regulates the DC link voltage whereas the inner current loop shapes the source current profile. The control mechanism implemented here is an effective, less complex, indirect scheme compared to the existing time domain control algorithms. Here, an intelligent fuzzy logic control regulates the DC link voltage which facilitates reference current generation for the current control scheme. The simulation of the said system was carried out in a MATLAB/Simulink environment. The simulations were carried out for different load conditions (RL and RC) using a fuzzy logic controller (FLC) and PI controllers in the outer loop (voltage control) and hysteresis current controller (HCC) and sinusoidal pulse width modulation (SPWM) in the inner loop (current control). The simulation results were extracted for dynamic load conditions and the results demonstrated that the THD can be reduced to 0.76% using a combination of SPWM and FLC. Therefore, the proposed system proved to be effective and viable for reducing THD. This system would be highly applicable for renewable energy power generation such as Photovoltaic (PV) and Fuel cell (FC). [ABSTRACT FROM AUTHOR]

This paper begins with a comprehensive review into the existing GaN device models. Secondly, it identifies the need for a more accurate GaN switching model. A simple practical process based on radio frequency techniques using Vector Network Analyser is introduced in this paper as an original contribution. It was applied to extract the impedances of the GaN device to develop an efficient behavioural model. The switching behaviour of the model was validated using both simulation and real time double pulse test experiments at 500 V, 15 A conditions. The proposed model is much easier for power designers to handle, without the need for knowledge about the physics or geometry of the device. The proposed model for Transphorm GaN HEMT was found to be 95.2% more accurate when compared to the existing LT-Spice manufacturer model. This work additionally highlights the need to adopt established RF techniques into power electronics to reduce the learning curve while dealing with these novel high-speed switching devices. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) resources are connected to power grid through voltage source inverters. The quality of power output from PV inverter should be in grid compliance of IEEE standard. In this regard, the deployment of appropriate low pass filters such as inductor (L), capacitor (C) or inductor capacitor inductor (LCL) is critical as they aid in minimizing the harmonics being injected into the grid. LCL filters are well entrenched but they bring in stability issue due to resonance and therefore a damping controller with suitable control logic is needed. In this work, to suppress resonance, a Proportional Resonant-Derivative (PR-D) controller has been designed, proposed, and compared with existing counterparts, i.e., two-degree of freedom controller (2DOF) and feedback current controller. The results exhibits that PR-D controller admits meliorate resonance damping and constancy when compared with the two other schemes. The whole system has been simulated in MATLAB/Simulink environment and a prototype has also been made to ensure the performance. [ABSTRACT FROM AUTHOR]