A comparative study of different optimization methods for resonance half-bridge converter

The LLC resonance half-bridge converter is one of the most popular DC-DC converters and could easily inspire researchers to design a high-efficiency and high-power-density converter. LLC resonance converters have diverse operation modes based on switching frequency and load that cause designing and optimizing procedure to vary in different modes. In this paper, different operation modes of the LLC half-bridge converter that investigate different optimization procedures are introduced. The results of applying some usual optimization methods implies that for each operation mode some specific methods are more appropriate to achieve high efficiency. To verify the results of each optimization, numerous simulations are done by Pspice and MATLAB and the efficiencies are calculated to compare them. Finally, to verify the result of optimization, the experimental results of a laboratory prototype are provided.Peer ReviewedPostprint (published version

Burden resistor selection in current transformers for low power applications

In order to sense AC current with electric isolation in high frequency switching power converters the most simple and low cost solution is to consider a current transformer with a burden resistor. But burden resistor selection is not a simple task because involves a lot of considerations that affect the output voltage and its signal-to-noise ratio and the bandwidth of the measure. In this paper, considering the basic equations of the transformer and applying the Laplace Transformation is obtained a simple model of the current transformer interesting to select burden resistor and even to design the current transformer in case of high frequency applicationsPostprint (published version

A novel high step-up secondary side impedance source full-bridge converter

In order to suppress the voltage stress of semiconductor devices, and solve the reverse recovery problem of diodes by decreasing the duty cycle of switches, impedance source converters could be consider as a solution. In this paper an impedance network is applied to the secondary side of a phase-shifted full-bridge converter in order to reduce the voltage stress of rectifier diodes. The proposed impedance network involves coupled inductors and capacitors that provide a new rectifier configuration for the converter. Operational principles of the proposed converter along with its theoretical analysis is investigated, and finally simulation results is provided by Pspice to verify the performance of the converter.Postprint (published version

Networked microgrid energy management based on supervised and unsupervised learning clustering

Networked microgrid (NMG) is a novel conceptual paradigm that can bring multiple advantages to the distributed system. Increasing renewable energy utilization, reliability and efficiency of system operation and flexibility of energy sharing amongst several microgrids (MGs) are some specific privileges of NMG. In this paper, residential MGs, commercial MGs, and industrial MGs are considered as a community of NMG. The loads’ profiles are split into multiple sections to evaluate the maximum load demand (MLD). Based on the optimal operation of each MG, the operating reserve (OR) of the MGs is calculated for each section. Then, the self-organizing map as a supervised and a k-means algorithm as an unsupervised learning clustering method is utilized to cluster the MGs and effective energy-sharing. The clustering is based on the maximum load demand of MGs and the operating reserve of dispatchable energy sources, and the goal is to provide a more efficient system with high reliability. Eventually, the performance of this energy management and its benefits to the whole system is surveyed effectively. The proposed energy management system offers a more reliable system due to the possibility of reserved energy for MGs in case of power outage variation or shortage of power.Peer ReviewedPostprint (published version

Component sizing of an isolated networked hybrid microgrid based on operating reserve analysis

The power-sharing possibility amongst microgrids (MGs) in networked microgrids (NMGs) offers multiple profits to the NMG by employing an applicable energy management system. An efficient energy management system can provide an adequate compromise in terms of the component sizing of NMGs through MG collaboration. This paper proposes a procedure to size the component for an isolated networked hybrid microgrid. The proposed design procedure relies on the optimum operation of individual MGs. The defined Reduced Factor (RF) identifies the possible size reduction for the dispatchable components, such as diesel generators and the energy storage system of each MG. The introduced RF is based on the operating reserve evaluation obtained from the optimal operation of individual MGs and the correlation between load profiles. Eventually, the simulation and practical results of a networked hybrid MG consisting of three MGs are presented to verify the proposed component sizing procedure. The practical results verify the theoretical expectations. The results show that NPC and capital costs are reduced up to 13% and 17%, respectively.The authors would like to thank the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN)—Agencia Estatal de Investigación (AEI) and the European Regional Development Funds (ERDF) by grant PGC2018-098946-B-I00 funded by MCIN/AEI/10.13039/501100011033/ and by ERDF A way of making Europe.Peer ReviewedPostprint (published version

Current sharing control strategy for IGBTs connected in parallel

This work focuses on current sharing between punch-through insulated gate bipolar transistors (IGBTs) connected in parallel and evaluates the mechanisms that allow overall current balancing. Two different control strategies are presented. These strategies are based on the modification of transistor gate-emitter control voltage VGE by using an active gate driver circuit. The first strategy relies on the calculation of the average value of the current flowing through all parallel-connected IGBTs. The second strategy is proposed by the authors on the basis of a current cross reference control scheme. Finally, the simulation and experimental results of the application of the two current sharing control algorithms are presented.Peer ReviewedPostprint (published version

High efficiency power amplifiers

Postprint (published version

Energy management of grid connected hybrid solar/wind/battery system using golden eagle optimization with incremental conductance

Renewable Energy Sources (RES) are currently being used on a much larger scale to support and satisfy the higher energy demands caused by industrialization and population growth. Due to this rise in the number of consumers of power systems and the unpredictable nature of the electric load, the vast power demand proves to be a tough challenge for electric utilities and system operators. So, power demands have occurred over many periods and become a threat to the system's functionality. Therefore, an effective Energy Management System (EMS) name called Golden Eagle Optimization with Incremental Conductance (GEO-INC) is proposed to meet the load demand. Three different systems, namely: RES Photovoltaic (PV) module, wind turbine, and battery create an effective EMS. The proposed method extracts more power from the PV panel and effectively controls the switching between the wind turbine and the battery storage system. The proposed method achieves 1.98 % distortion from the results, which is less than the existing methods.The authors would like to thank the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN)-Agencia Estatal de Investigación (AEI) and the European Regional Development Funds (ERDF), by grant PGC2018-098946-B-I00 funded by MCIN/ AEI/10.13039/501100011033/ and by ERDF ERDF A way of making EuropePeer ReviewedPostprint (published version

Power improvements in grid-connected PV system using hybrid technologies

Power-sharing in a microgrid community (MGC) requires mandatory strategies in order to stabilize the system by maintaining the rated frequency and voltage. The hierarchical control strategy is the most adopted control structure due to providing seamless operation in transient between islanded and grid-connected modes. Droop control strategy is discussed in this paper to control the voltage source inverter (VSI) in power exchange mode with other microgrids (MGs) or main utility grid. After analysing the average model of three-phase VSI, the voltage and current transfer functions are obtained according to the considered droop controller. The stability and seamless operation of the system are analysed, and the simulation results verify the control loops of the VSI can handle the power variation of the MG effectively.Peer ReviewedPostprint (published version

Power quality improvements in grid-connected PV system using hybrid technology

In recent trends, photo-voltaic (PV) is mostly build upon competitive technological development of power quality (PQ) issues. In this article, a hybrid control strategy is implemented with multi-level inverter (MLI) to improve PQ features. As a result, the combination of these controllers with suitable level of MLI could improve the PQ features in a significant way.Peer ReviewedPostprint (published version