Current Harmonic Aggregation Cases for Contemporary Loads

Power electronic circuits in modern power supplies have improved the conversion efficiency on the one hand but have also increased harmonic emissions. Harmonic currents from the operation of these units affect the voltage waveforms of the network and could compromise the reliability of the network. Load and source non-linearity can, therefore, limit the renewable source’s hosting capacity in the grid, as a large number of inverter units may increase the harmonic distortions. As a result, voltage and current distortions could reach unbearable levels in devices connected to the network. Harmonic estimation modelling often relies on measurement data, and differences may appear in mathematical simulations as the harmonic aggregation or cancellation may generate different results due to the inaccuracies and limitations of the measurement device. In this paper, the effect of harmonic currents cancellation on the aggregation of different load currents is evaluated to show its impact in the network by presenting a comparison between the measurement and mathematical aggregation of harmonics. Furthermore, the harmonic cancellation phenomenon is also qualified for multiple loads connected to the power supply.

Dirac-Source Diode with Sub-unity Ideality Factor

An increase in power consumption necessitates a low-power circuit technology to extend Moore’s law. Low-power transistors, such as tunnel field-effect transistors (TFETs)1-5, negative-capacitance field-effect transistors (NC-FETs)6, and Dirac-source field-effect transistors (DS-FETs)7-10, have been realised to break the thermionic limit of the subthreshold swing (SS). However, a low-power diode rectifier, which breaks the thermionic limit of an ideality factor (η) of 1 at room temperature, has not been proposed yet. In this study, we have realised a DS diode, which exhibits a steep-slope characteristic curve, by utilising the linear density of states (DOSs) of graphene7. For the developed DS diode, η < 1 for more than two decades of drain current with a minimum value of 0.8, and the rectifying ratio is large (> 105). The realisation of a DS diode paves the way for the development of low-power electronic circuits.

Gallium-Nitride Field Effect Transistors in Extreme Temperature Conditions

Compact power electronic circuits and higher operating temperatures of switching devices call for an analysis and verification on the impact of the parasitic components in these devices. The found drift mechanisms in a gallium-nitride field effect transistors (GaN-FET) are studied by literature and related to measurement results. The measurements in extreme temperature conditions are far beyond the manufacturer-recommended operating range. Influences to parasitic elements in both static and dynamic operation of the GaN-FETs are investigated and related toward device losses in switch-mode power electronic circuits with the example of a half-bridge circuit. In this article, static operation investigation on the effect of temperature toward resistance, leakage currents, and reverse conduction is conducted. Dynamic operation between the two states of GaN-FET is also addressed and related to the potential impact in a switching circuit losses. A thermal chamber was built to precisely measure the effect of temperature toward parasitic elements in the devices using a curve tracer. It was found that the increment in RDSon, IDSS, IGSS, and VSD can be justified by the literature and verified by measurements. Incremental COSS and decreasing VGSth was found when exposing devices to extreme temperatures. These two parameters give real challenge over designing circuits at high temperature where timing is critical. Albeit temperature challenges, it is found that investigated GaN-FETs have potential to be used in extreme temperature-operating conditions.

A Review on Small Power Rating PV Inverter Topologies and Smart PV Inverters

The two most critical deciding factors for power consumption are energy efficiency and cost. Power electronic circuits are widely used and play an important role in achieving high efficiency in power distribution to customers and power transfer from source to load. Furthermore, solar energy is abundant, sustainable, and pollution-free in nature. Power electronic circuits are used in high-power applications with voltages ranging from a few millivolts to thousands of volts and wattages ranging from a few mW to megawatts. This paper examines a variety of inverter topologies and their modeling, as well as a comparison of single-stage and multi-stage/inverter topologies depending on the application. The main aim of control techniques is to keep Total Harmonic Distortion (THD) to a minimum and the switching frequency within the permissible range so that inverters for renewable energy sources, electric vehicles, uninterruptible power supply (UPS) systems, and hybrid energy storage systems can work efficiently. Plug-and-play, adaptability, self-awareness, and other features should all be included in a smart inverter. Based on the findings of this comparative analysis, selection criteria are established. This comparative analysis can be used to develop selection criteria for choosing inverter circuits for the various applications described in this paper.

Design and Applications of Controllable Magnetic Devices in Power Electronic Circuits and Power Systems

Magnetic components are characterized by high robustness and reliability. Controllable magnetic components, which used to dominate, have been out of fashion for about 50 years. However, they have great advantages in terms of longevity, radiation resistance and overload capacity and become smaller and smaller with increasing operating frequency. This makes them interesting in modern power electronics applications with the increasing use of WGB semiconductors. The article shows how the performance of power electronic converters can be improved with modern power electronics and with field-controlled magnetic components using modern magnetic materials. Keywords: Magnetic components; Passive components; Modelling; Magnetic amplifiers; Controllable filters;