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This paper assesses the impact of the new SiC switching technology vs. Si MOSFETs to provide optimal efficiency for a 5 kW bidirectional H6 inverter intended for residential building applications. The study applies an analytical model to predict the losses of a synchronous H6 transformer-less topology based on PSIM simulation results. The results show that SiC provides up to 98.3% efficiency compared to 93.6% achieved with Si. In addition, further improvement of efficiency is achieved by increasing the operational frequency up to 50 kHz, whereby the passive components size is also reduced.

The increasing deployment of photovoltaic systems and behind-the-meter batteries into power distribution systems has increased interest in optimal system operating conditions. Electricity tariff, as an indirect factor, plays a pivotal role in controlling the customers’ behavior, especially in the presence of batteries. The residential sector, as one of the largest consumers, requires accurate analysis of the impacts of tariffs on its load profile for short-term and long-term planning. In this paper, a household equipped with a photovoltaic array and battery is modeled and the effects of flat-rate, stepped rate, time-of-use, and demand charge pricing structures on the battery charge/discharge model are analyzed. Furthermore, the effects of COVID-influenced consumption patterns and the increase in feed-in tariff for photovoltaic energy on battery scheduling are investigated. The battery scheduling problem is formulated as a non-linear optimization function, to minimize electricity costs for customers, and is solved using a Genetic algorithm.

In this paper, state-of-the-art power electronics and energy management solutions utilized in low-power (less than 5 mW), low-voltage (less than 3 V) energy harvesting powered wireless sensors for Internet of things related applications are detailed. All aspects of an energy harvesting powered sensor system are examined, including the challenges of low-power energy harvesting sources, energy management circuits including power converters and energy storage elements, as well as the impact of wireless sensor pulsed power profiles. In particular, this paper focuses on existing voltage step-up energy management techniques, including the issues of cold-start and maximum power point tracking, as well as energy storage which is necessary for wireless sensor operation. Both academic and commercially available energy harvesting powered systems are examined to provide a comprehensive analysis of existing solutions. Issues that are limiting the current system performance are identified to help define future developments needed to enable efficient and effective energy harvesting powered wireless sensor operation.

This paper describes the design of a high-efficiency energy management system for low-power, low-voltage energy harvesting powered wireless sensor systems. With typical voltages of less than 1 V and power levels lower than 1 mW, there are significant challenges when applying energy harvesting sources to supply pulsed power levels of up to 120 mW at voltage levels of 1.8–4 V as required by wireless sensor loads. The proposed approach integrates energy storage elements within a voltage step-up circuit to produce a new high-efficiency energy management circuit that converts the energy produced by a low-power, low-voltage source into a series of high power pulses. An optimized switched supercapacitor energy buffer circuit including a self-powered control circuit is proposed. Efficiencies of up to 91% are shown for an indoor solar cell source with a power level of 0.5 mW, supplying an equivalent wireless sensor with pulsed power levels of 10–120 mW. This is significantly higher than 83% achieved for the dc–dc stage of the existing best solution under the same source conditions, but requires an additional conversion step to provide high power pulses.

By increasing energy trading in a microgrid, we can reduce the energy burden of the main grid, generate surplus power, reduce transmission and distribution losses, and save electricity bill. One of the options for curbing surplus energy flow, which will help maintain a dynamic equilibrium in the power grid between supply and demand, is Peer to Peer energy trading. When players form a group to strengthen their position and increase their payoff in a game, they are referred to as coalitions. An optimal coalition is designed in this work using the Fractional Hedonic Games mechanism, in which a player’s utilities is the average of all the other players in a coalition. The objective of using FHG is to consider each player’s preference in the game, as other games in the literature do not consider preference relations. We argued that the proposed coalition is better than the grand coalition and proved optimal and stable with a better payoff.

This paper presents a method for overcoming reduced light-load efficiency imposed by bidirectional inverters integrated with a DC distribution system powered by renewable energy. An evaluation of existing topologies to achieve optimal efficiency is presented, and loss breakdown under light-load is investigated using analytic models and PSIM simulation. The study proposes a novel synchronous H6 transformer-less topology. The results show that the proposed topology at achieves 98.3% light load efficiency (at 20% load) when operated in inverter mode, whereas 96.5% is obtained at full load, both which are higher than the standard H6 topology efficiency by 4.5% and 1.5%, respectively. The rectifier mode shows similar levels of improvement of 4% at light load and 1.2% for under full load conditions.

This work presents analytical expressions for the DC inductance of 3D air core inductors with circular cross section pillars (CCSP) and rectangular cross section pillars (RCSP). We consider the following four types of inductor structures: (1) a toroid with CCSP; (2) a toroid with RCSP; (3) a solenoid with RCSP; and (4) a solenoid with CCSP. For each type, a unique analytical model is developed for obtaining DC inductance. High frequency (1-100 MHz) effects on inductance are also discussed. The inductance values predicted by the proposed analytical models of the first three types of inductor structures are in an acceptable agreement with numerical Finite Element Analysis (FEA) solutions, where the maximum difference is 7.3%. Also, our analytical model for the fourth type inductor reduces the error, when correlated with FEA inductance value, up to 6× compared to previously published models. A comparison of results using proposed analytical expressions with published measured values as well as our measurement data demonstrates error ranging from 0.5 to 16.2%, while conventional formulae show errors of up to 143%. The results of the proposed models could serve as a good initial estimate for power supply on chip (PwrSoC) and power supply in package (PSiP) applications.

Size reduction of passive components in power converters especially magnetic components is essential to reduce the overall size of the converter and achieve higher power densities. For that purpose, this paper presents a detailed design procedure of a 4th order resonance output filter to show the advantages it provides in terms of passives size and loss reduction. A design study comparison is presented between 2nd order, 4th order and 4th order resonance filters in a 5.4 W, 20 MHz buck converter with PCB integrated solenoid inductors. The comparison considers the same circuit specifications and PCB manufacturing capabilities for the PCB inductors. It is found that there is potential for a total inductor size reduction of 38% with a corresponding increase in full load inductor efficiency of 2.1% and full load circuit efficiency of 1.3% provided by the 4th order resonance filter compared to a standard 2nd order filter in a 5.4 W buck converter switching at 20 MHz.

Traumatic brain injuries and damage are major causes of death and disability. We propose a 3D fully coupled electro-mechanical model of a nerve bundle to investigate the electrophysiological impairments due to trauma at the cellular level. The coupling is based on a thermal analogy of the neural electrical activity by using the finite element software Abaqus CAE 6.13-3. The model includes a real-time coupling, modulated threshold for spiking activation, and independent alteration of the electrical properties for each 3-layer fibre within a nerve bundle as a function of strain. Results of the coupled electro-mechanical model are validated with previously published experimental results of damaged axons. Here, the cases of compression and tension are simulated to induce (mild, moderate, and severe) damage at the nerve membrane of a nerve bundle, made of 4 fibres. Changes in strain, stress distribution, and neural activity are investigated for myelinated and unmyelinated nerve fibres, by considering the cases of an intact and of a traumatised nerve membrane. A fully coupled electro-mechanical modelling approach is established to provide insights into crucial aspects of neural activity at the cellular level due to traumatic brain injury. One of the key findings is the 3D distribution of residual stresses and strains at the membrane of each fibre due to mechanically induced electrophysiological impairments, and its impact on signal transmission. The authors gratefully acknowledge funding from the Galway University Foundation, the Biomechanics Research Centre, and the Power Electronics Research Centre, College of Engineering and Informatics, National University of Ireland Galway (NUIG) in Galway, Rep. of Ireland. peer-reviewed

This paper investigates the potential volume reduction of a transformer for a Series Resonant Converter (SRC), using silicon carbide semiconductors, in a Ground Power Unit (GPU) application. Using an optimization based theoretical and empirical transformer design methodology, it is shown that the series resonant transformer volume has a large potential volume reduction below 50-60 kHz operation, but limited potential reduction above these operating frequencies. A 15 kW, 50 kHz transformer is designed and the simulated/modelled efficiency of the full SRC converter, shows a peak efficiency of 98.45 %.

Objective: We propose a novel approach for modelling the interdependence of electrical and mechanical phenomena in nervous cells, by using electrothermal equivalences in finite element (FE) analysis so that existing thermomechanical tools can be applied. Methods: First, the equivalence between electrical and thermal properties of the nerve materials is established, and results of a pure heat conduction analysis performed in Abaqus CAE Software 6.13-3 are validated with analytical solutions for a range of steady and transient conditions. This validation includes the definition of equivalent active membrane properties that enable prediction of the action potential. Then, as a step toward fully coupled models, electromechanical coupling is implemented through the definition of equivalent piezoelectric properties of the nerve membrane using the thermal expansion coefficient, enabling prediction of the mechanical response of the nerve to the action potential. Results: Results of the coupled electromechanical model are validated with previously published experimental results of deformation for squid giant axon, crab nerve fibre, and garfish olfactory nerve fibre. Conclusion: A simplified coupled electromechanical modelling approach is established through an electrothermal equivalent FE model of a nervous cell for biomedical applications. Significance: One of the key findings is the mechanical characterization of the neural activity in a coupled electromechanical domain, which provides insights into the electromechanical behaviour of nervous cells, such as thinning of the membrane. This is a first step toward modelling three-dimensional electromechanical alteration induced by trauma at nerve bundle, tissue, and organ levels. The authors acknowledge funding from the Galway University Foundation, the Biomechanics Research Centre and the Power Electronics Research Centre, College of Engineering and Informatics, National University of Ireland Galway. peer-reviewed

The energy sector is undergoing a paradigm shift to integrate the increasing volume of embedded renewable energy generation and creating local energy communities or LECs that have been an essential component in increasing the same. Peer to Peer (P2P) energy trading is one of the alternatives to curb the surplus energy flow and would also help in maintaining a dynamic balance between supply and demand in the power grid. In this paper, we propose a P2P energy trading mechanism with distributed solar photovoltaic, community battery storage, and electric vehicle charging points. Game theory is the most widely used approach for P2P energy trading because of its characteristic of solving complicated interactions between provider and receiver. In the present work, we have considered a coalition based cooperative game theory framework whose objective is to maximize the total profit of the coalition. The simulation framework of this mechanism has been tested on a local energy community with 100 households having 50 consumers and 50 prosumers creating a win-win approach for both consumers and prosumers (users able to generate and consume simultaneously). Various trading scenarios have been proposed in this paper depending on geographical location, maximum energy demand, and maximum energy generated. These trading scenarios have been tested on a low voltage model to check their feasibility for a real network. The best operational performance priority at each timeslot with solar PV and community storage has also been analysed.

The performance factor (PF) for magnetic materials originated with S.A. Mulder [1] to compare different grades of ferrite materials. It essentially consists of a plot of the product of the frequency ( f ) and flux density ( B ) versus frequency at a specified level of power loss per unit volume.

The purpose of this paper is to investigate methods for improving power delivery from low-voltage, low-power energy harvesting sources, such as small form-factor dye-sensitised solar cells (DSSCs) as used in autonomous wireless sensing applications in buildings and homes. Energy harvesting powered wireless sensors enable existing and new structures to comply with Industry 4.0 and become smart buildings. Due to the size constraints of wireless sensor systems and the inherently low-power levels generated by energy harvesting sources, available power is limited and therefore the efficiency of power conversion and energy management circuitry connected between the source and output load has a significant impact on output power delivery. Most research to date focuses on improving the efficiency of individual components of such systems, without considering the impact of one stage on the others. In this paper, the potential of varying energy harvesting source configuration in combination with power converter operation to improve overall power delivery is investigated, where it is shown that by connecting sections of a DSSC in series rather than as a single cell, higher power conversion efficiency and therefore power delivery is achieved. Limitations to varying cell configurations and low-power DC-DC topologies are illustrated in order to demonstrate the scope of solutions available for small-sized, low-power, energy harvesting sources. It is shown that 8% improvement in overall power delivery is achieved for series vs. single cell connections within a fixed module area. This will translate into increased wireless sensor functionality and range, thereby furthering the development of the Industrial Internet of Things in buildings and homes.

Microbial electrochemistry merges microbiology, electrochemistry and electronics to provide a set of technologies for environmental engineering applications. Understanding the electronic concepts is crucial for effectively adopting these systems, but the importance of electronic circuitry is often overlooked by microbial electrochemistry researchers. This review provides the background on the electronics and electrochemical concepts involved in the study of microorganisms interacting with electricity, and their applications in microbial electrochemical technology (MET). The potentiostat circuitry is described along with its working principles. Electrochemical analyses are presented together with the rational and parameters employed to study MET devices and electroactive microorganisms. Finally, future directions are delineated towards the adoption of MET, and the related electronics, in environmental engineering applications. This work has been financed by the Science Foundation Ireland (SFI) Research Professorship Programme Innovative Energy Technologies for Biofuels, Bioenergy and a Sustainable Irish Bioeconomy (award no. 15/RP/2763). The authors thank Uwe Schröder group (Technische Universität Braunschweig, Germany) for kindly permitting re-using their data to plot the graphs shown on Fig. 8. peer-reviewed 2021-11-16

Research and industry interest in improving performance, size and cost of DC-DC converters is driving the development of circuit topologies and passive components that are compatible for integration on silicon, particularly magnetic components. In order to quantify the advantages of coupled inductors, this paper presents a design case comparison between coupled vs. non-coupled silicon-integrated microfabricated inductors in a 2 W interleaved DC-DC converter switching at 20 MHz, considering the same circuit specifications and silicon manufacturing capabilities for the silicon-integrated inductors. The study attempts to address the relative advantages and disadvantages of each design in terms of inductor size, loss and circuit transient response, in addition to presenting a selection procedure for a suitable coupling factor that provides flux cancellation over a range of input voltages for 4-phase cyclic cascaded coupled inductor.

Coupled inductors offer significant advantages over their uncoupled counterparts; however, with these advantages come a number of additional design caveats. The factors affecting the design and optimization of coupled stripline microinductors for PwrSoC applications are outlined, which include device area, the number of coupled phases, duty cycle, paralleling of coupled inductors, switching frequency, as well as thermal and saturation constraints. Results of this analysis are presented and discussed along with guidelines for the design of coupled stripline microinductors, which show that paralleling coupled inductors is the best route toward higher output current. Analytical models predict a peak inductor efficiency of 86.8% and 86.3% for fabricated 3 and 5-phase coupled stripline microinductors with an Ni45Fe55 core, respectively. Models are verified by measurements on prototype 3 and 5-phase converters with parallel coupled stripline microinductors over a range of operating conditions.

In this paper, models that account for the duty cycle and phase shift angle of the applied phase voltages in coupled stripline microinductors are presented and are shown to have a significant impact on harmonic current amplitudes and therefore microinductor efficiency. The impact of a high coupling factor between two windings surrounded by a single core is also investigated. The models are validated using finite-element analysis and measurements. A three-phase-coupled microinductor has been fabricated with a Ni45Fe55 core and analyzed for a number of operating conditions. A prototype 1.6 W, three-phase converter utilizing this inductor has also been measured and is discussed in detail. The coupled microinductor is predicted to have a peak efficiency of 86.6% at 20 MHz in the prototype circuit.

In circuits where there is an inherent phase shift angle between coupled winding currents such as in coupled inductors, it is important to accurately calculate the ac winding loss at the correct phase shift and frequency. Phase shift between winding currents can cause the ac winding loss to vary significantly due to changes in the magnetic field distribution. This paper presents an analysis of winding loss for the general case of coupled windings with arbitrary phase-shifted currents and its effect in a number of practical devices. A detailed approach to analytically calculate ac winding loss in microfabricated-coupled stripline inductors is presented along with a derivation of the resistance matrix for the device. The analysis and methodology are then validated using finite element analysis and experimental results.

The aim was to investigate mechanical and functional failure of diffuse axonal injury (DAI) in nerve bundles following frontal head impacts, by finite element simulations. Anatomical changes following traumatic brain injury are simulated at the macroscale by using a 3D head model. Frontal head impacts at speeds of 2.5-7.5 m/s induce mild-to-moderate DAI in the white matter of the brain. Investigation of the changes in induced electromechanical responses at the cellular level is carried out in two scaled nerve bundle models, one with myelinated nerve fibres, the other with unmyelinated nerve fibres. DAI occurrence is simulated by using a real-time fully coupled electromechanical framework, which combines a modulated threshold for spiking activation and independent alteration of the electrical properties for each three-layer fibre in the nerve bundle models. The magnitudes of simulated strains in the white matter of the brain model are used to determine the displacement boundary conditions in elongation simulations using the 3D nerve bundle models. At high impact speed, mechanical failure occurs at lower strain values in large unmyelinated bundles than in myelinated bundles or small unmyelinated bundles; signal propagation continues in large myelinated bundles during and after loading, although there is a large shift in baseline voltage during loading; a linear relationship is observed between the generated plastic strain in the nerve bundle models and the impact speed and nominal strains of the head model. The myelin layer protects the fibre from mechanical damage, preserving its functionalities. The authors acknowledge funding from the Galway University Foundation, the Biomechanics Research Centre and the Power Electronics Research Centre, College of Engineering and Informatics, NUI Galway (Galway, Republic of Ireland). peer-reviewed