In this study, we compare time-series and neural networks models capturing long memory for electricity price forecasting in the Russian day-ahead market. We identify the presence of long memory in hourly wholesale electricity price series across six regions of the Russian power grid. Using dedicated statistical tests, we confirm strong long-range dependence and estimate the corresponding long memory parameters. To investigate the potential enhancement in forecasting accuracy offered by long-memory models, we implement a set of fractionally integrated time series models, alongside Long Short-Term Memory (LSTM) and Deep Neural Network (DNN) machine learning models. We evaluate forecasting performance using both in-sample and out-of-sample tests: the in-sample evaluation corresponds to one-hour-ahead predictions, while the out-of-sample evaluation simulates actual day-ahead market conditions. In most cases, the Seasonal Autoregressive Fractionally Integrated Moving Average model with calendar regressors (SARFIMAX) outperforms other time series models and neural networks. The best-performing model, SARFIMAX(1,0,0)(0,D,0)24, achieves an average forecasting improvement of approximately 0.5% compared to the DNN.

Switch-mode power converters commonly operate at switching frequencies from kilohertz to a few megahertz, traditionally relying on silicon-based transistors and control circuitry. However, parasitic limitations in silicon devices constrain further frequency scaling. This article presents a fully gallium nitride (GaN)-based dc-dc converter designed for high-frequency operation. The proposed architecture employs a GaN-based ring oscillator for on-chip pulsewidth modulation generation and includes all converter modules operating within the 8-43 MHz range. Experimental results validate the proposed design, demonstrating its feasibility and performance in high-frequency power conversion. The findings support the development of integrated GaN-based power conversion systems for advanced system-on-chip applications.

This work explores the principle of utilizing gallium nitride devices as a gate driver for silicon carbide power devices. As silicon has long reached its performance limits, Wide Bandgap semiconductors such as gallium nitride and silicon carbide have emerged as promising alternatives due to their superior characteristics. However, few publications suggest using a gallium nitride-based gate driver for silicon carbide, high-voltage power devices. Unlike standard voltage source gate drivers, this paper proposes a novel bi-polar current source resonant gate driver topology using gallium nitride transistors as a gate drive circuit for silicon carbide power switching. The driver receives a single input supply and pulsed width modulation signal, producing a high current bi-polar gate driving signal. The gate driver is validated by employing the proposed gate driver to a high-power silicon carbide transistor in a resonant boost converter. The experimental results show that the new gate driver recovers the gate charge wasted energy and provides high performances in varying high voltage loads at a 2.5 MHz switching frequency while reducing the gate losses by 26%.

Power converters are increasingly pushing toward higher switching frequencies, with current designs typically operating between tens of kilohertz and a few megahertz. The commercialization of gallium nitride (GaN) power transistors has opened new possibilities, offering performance far beyond the limitations of conventional silicon devices. Despite this promise, the potential of GaN technology remains underutilized. This paper explores the feasibility of achieving sub-gigahertz switching frequencies using GaN-based switch-mode power converters, a regime currently inaccessible to silicon-based counterparts. To reach such operating speeds, it is essential to understand and quantify the intrinsic frequency limitations imposed by GaN device physics and associated parasitics. Existing power conversion topologies and control techniques are unsuitable at these frequencies due to excessive switching losses and inadequate drive capability. This work presents a detailed, systematic study of GaN transistor behavior at high frequencies, aiming to identify both fundamental and practical switching limits. A compact analytical model is developed to estimate the maximum soft-switching frequency, considering only intrinsic device parameters. Under idealized converter conditions, this upper bound is derived as a function of internal losses and the system’s target efficiency. From this, a soft-switching figure of merit is proposed to guide the design and layout of GaN field-effect transistors for highly integrated power systems. The key contribution of this study lies in its analytical insight into the performance boundaries of GaN transistors, highlighting the roles of parasitic elements and loss mechanisms. These findings provide a foundation for developing next-generation, high-frequency, chip-scale power converters.

The lengthy process of sizing and optimizing hybrid energy sources requires an accurate battery model. This paper presents a generic new energy storage system model premeditated to solve the optimization problem of the sizing procedure. The model comprises several methods, a lookup table, an equivalent battery circuit, and analytical equations. The database is created offline based on experimental results achieved under various conditions. In the first step, the model receives an external vector of signals comprising load power demand, instantaneous generated energy, and ambient temperature. Then, the algorithm predicts the impact of the load on the battery parameters by either interpolation or extrapolation. The results are utilized at an equivalent circuit that supplies the basic parameters and the battery constraints. Next, analytical methods reveal the more advanced parameters such as charge, supplied and remaining energy, etc. The results show that the proposed dynamic battery model can predict the battery states through all operating zones and under different battery conditions. The benchmark results present higher accuracy than other available models. The proposed model was employed in a sizing procedure to verify the model’s accuracy. It was shown that the new model estimates the required source rating more precisely than standard models. Since the suggested algorithm is based on actual battery curves, it can be utilized for all types of batteries by reentering the data of any other battery.

Power factor correction (PFC) is necessary for any load that is connected to the electrical grid. Most electronic circuitry requires low DC voltage, while the majority of utilized PFCs are based on boost converters that supply high DC voltage at their output terminal. The electric vehicle market has recently evolved dramatically; its battery voltage varies from a few hundred to almost a thousand volts, depending on the manufacturer. Thus, a two-step conversion is necessary when charging it from the electrical grid. This paper presents a new type of front-end universal step up / down three voltage level PFC. Then, a detailed description of the rectifier’s principle of operation will be provided, and the analysis of continuous conduction modes will be conducted. Finally, the proposed theory is validated in a cascade dual closed loop mode simulation. An internal inductor current and external voltage loop. The rectifier is examined at different battery pack voltage levels while presenting a near-unity power factor with low harmonic distortion.

A new type of single–conversion–step wide–input–range versatile step–up/down three–voltage–level power–factor correction stage is presented in this manuscript. The rectifier can operate both in continuous–conduction mode and discontinuous–conduction mode. First, the rectifier’s principle of operation is described, and then the innovative rectifier is analyzed in continuous and discontinuous–conduction modes. After, an average model for the innovative rectifier is developed. Lastly, the proposed theory is experimentally validated using a multiplier–less dual–control–loop mode at discontinuous–conduction modes. It is shown that although no multiplier is used in the control circuitry, the power factor is near unity. It is revealed that the rectifier can swing the output voltage from 50 V to 900 V while the input voltage is 230 Vrms. Although the rectifier output has a split DC bus with three voltage levels, the required control effort is low, and the output voltage is balanced. The innovative topology suits any standard power–factor correction rectifier application, dual–stage low–voltage power supply, and three–level voltage supplement for low–harmonic inverters. Since the rectifier’s output–voltage swing is extremely wide, energy storage systems and electric vehicle batteries are suitable applications.

Series-stacked buffer (SSB)-based active dc links aim to increase power density by replacing bulky dc link capacitor with series connection of significantly lower valued capacitor and auxiliary bidirectional dc/ac converter. SSB design constraint describing quantitative relation between passive components values and system power rating was established to achieve minimal remaining dc link voltage ripple magnitude. This letter generalizes the above requirement, revealing that allowing nonminimum magnitude of residual dc link voltage ripple releases other design constraints, yielding a more optimal solution in terms of full-rating capacitance utilized and/or auxiliary bidirectional dc/ac converter volt-ampere rating. Experimental results validate the proposed methodology, matching corresponding analytical predictions.

This paper explores practical implementation of an active decoupling device integrated into a commercial 120-watt LED driver. The device, employing a series-stacked buffer (SSB)-active DC link, replaces the traditional DC-bus electrolytic capacitor. Utilizing an auxiliary total capacitance smaller than a third of the original capacitance, the device effectively emulates the low-frequency characteristics of a significantly larger capacitance. The central obj ective of this study is to showcase the feasibility of incorporating small electrolytic auxiliary capacitors instead of ceramic class two capacitors and to design a high-power-density, compact electronic board capable of effectively replacing a large electrolytic capacitor. It is essential to note that the objective was not to optimize the physical size or cost of the proposed device but to emphasize its ability to operate identically or even improve the performance of a commercial product. Constraints on applicable auxiliary capacitors, including their rated voltage and maximum ripple current, are also considered. The Total Harmonic Distortion (THD) of the input mains current and DC-bus voltage ripple was compared between the original and modified LED drivers.

This paper presents an extension of a 5-level T-Type inverter to a high-power multi-level inverter that can be implemented in electric vehicles and trucks. The proposed inverter possesses several advantages over standard topologies such as Neutral Point Clamped, Flying Capacitor, and Cascaded H-bridge. The main advantages are a low number of components, an estimated lower price and weight, smaller dimensions, and the implementation of only one DC voltage source per phase. The proposed topology can be implemented for any required odd number of voltage levels. Due to the estimated reduced dimensions and weight, the proposed topology is especially suitable for electric transportation applications. The operation of the proposed topology was validated for 9- and 13-level configurations under PD, POD, and APOD PWMs. The simulation results show the inverter's practicability for supplying motors of electric trucks.

This paper introduces an approach to calculating the minimum value of split DC link capacitance in three-phase three-level grid-connected DC-AC converters operating with unity power factor without either active balancing circuits or AC zero sequence injection. Due to the fact that partial DC link voltages and rectified mains phase voltages reach their maximum and minimum values, respectively, at different time instants, it is feasible to decrease the minimum value of the former below the maximum value of the latter while still maintaining proper functionality of the power stage. The minimum possible split DC link capacitance values are hence derived from the boundary condition where the above-mentioned voltages are tangent to each other. The accuracy of the analytical derivations is confirmed by simulations and experiments carried out on a 10 kVA T-type converter prototype, which show a high degree of agreement.

Batteries are the foundation stone of the hybrid-electric vehicle, where the powertrain is made of a battery and an energy source. An accurate battery model is a necessary tool for a successful sizing procedure. This paper presents a new generic battery model for the sizing process; it utilizes different methods of battery mocking up into one model. Firstly, a database is created based on battery tests performed under various conditions. Then, the model receives the real-time power demand and signals of the environment status; then, the algorithm characterizes the parameter changes. The algorithm interpolates and extrapolates the data to find the predicted operating point. The findings are fed into a battery-equivalent circuit where some basic parameters are revealed. Then, analytical equations are employed to supply all battery parameters. The outcomes show that the proposed generic model can better predict the battery parameters through all operating regions under varying conditions. The suggested algorithm could be designed for all types of batteries by reentering the data for any specific battery. A case study was made on the lithium ferro-phosphate (LiFePo4) battery. The experimental results demonstrate that the proposed model is more accurate than the others; thus, the sizing results are more optimal.

This paper proposes a new resonance-type FCL, which is designed specifically for DFIG-based wind turbines. The proposed topology overcomes the well-documented drawbacks associated with conventional resonance-based FCLs while preserving the advantages of this topology. The proposed circuit limits the fault current for the entire fault period independently of the reactor's charging state and significantly reduces the wind turbine's torque oscillations during a fault. The proposed FCL is simulated as part of a power system that includes a wind turbine, synchronous generator, and two step-up transformers. The results show that during a three-phase toground fault, the proposed FCL significantly improves the system's stability, and leads to improved fault current, voltage, active power, reactive power, and torque transients.

This paper reviews different types of capacitors and auxiliary source circuit topologies and presents an introduction to control strategies used for circuit applications reducing DC-BUS capacitance. The paper argues in favor of replacing bulky electrolytic capacitors in capacitor-supported power electronic systems with auxiliary source circuits. DC-BUS capacitors are widely used in grid-tied power converters (rectifiers) and utilized for power balance, voltage ripple limitation, and short-term energy storage. The electrolyte capacitor is the Achilles heel of any rectifier and power converter due to its higher rate of failure than other circuitry components. Auxiliary source circuits are key components to qualitatively improve the reliability of the DC links, where they divert the instantaneous pulsating power into extra reliable storage components. Unlike previous work, this review serves to provide a clear picture of an auxiliary source circuit design, in favor of optimal solution selection according to the specific application. Therefore, energy storage components (capacitors), topologies, and control strategies of auxiliary source circuits are comprehensively reviewed in this paper. Additionally, detailed explanations, comparisons, and discussions of auxiliary source circuits are offered.

Mains-connected converters must correct the power factor to fulfill different power quality requirements. As a result, power factor correction (PFC) circuits have been developed in the 80s the past century and nowadays are mandatory. However, while most devices fed from rectifiers require a low voltage, most of the PFC today are based on Boost converters. Consequently, an additional conversion step between the rectifier and the target load is required. The cascade connection makes the power-supply system to be more expensive, larger, and less efficient. This paper presents a new rectifier topology, based on Buckboost converter, that will enable to supply a regulated step up / step down output voltage, over a wide range, while keeping all required power quality standards for a variety of applications. First, the operation principles of the converter are explained, then an analysis is performed for an inductor current discontinuous conduction mode (DCM), and simulation results of the rectifier are introduced.

Flyback converter is well-known topology and utilized in many applications where galvanic isolation or a high ratio conversion rate is required. This paper presents a new topology of an isolated switch mode power-converter. The fixed-frequency quasi-resonant converter is based in flyback family operating in discontinues conduction mode. The converter uses zero-voltage-switching techniques to improve the converter efficiency. The converter comprises coupled inductor, two switches, and a diode on the primary side. At the secondary side, there is a diode, coupled inductor, and output capacitor. The new topology enables to run the converter at constant switching frequency while preforming a quasi-resonance behavior. In this paper, the innovative topology is presented. First, the circuit operation steps are described, then the analytical equations are developed. To validate the proposed theory a case study was made; the circuit was modeled by PSIM simulation tool. The results are acknowledged that the innovative topology can decrease the circuit losses dramatically throughout all operating points.

This paper discusses a different auxiliary source circuit topologies and the introduction of control strategies used for auxiliary source circuit, in favor of bulky electrolytic capacitor replacement in capacitor-supported power electronic systems. DC-BUS capacitor is widely used in grid-tied power converters for power balance, voltage ripple limitation, and short-term energy storage. Auxiliary source circuits are key components to improve the reliability of the dc-links qualitatively, making a great effort to divert the instantaneous pulsating power into extra reliable storage components. Topologies and control strategies of an auxiliary source circuit are comprehensively reviewed in this paper. Additionally, detailed explanation, comparison, and discussion on the auxiliary source circuit are achieved.

The Pulsed width modulator is a fundamental circuit in any electronic power converter. In this paper a new topology for pulsed width modulator based on Gallium Nitride transistors is presented. First the circuit is analyzed for allowing the control of the switching frequency operation and the control of the on and off lime. The proposed theory is validated by simulation and experiment. The results show that the proposed ring oscillator circuit is capable of being employed as a self-oscillating pulse width modulator even for very high frequency power converter.

Hybridization of sources is spreading worldwide by utilizing renewable sources and storage units as standard parts of every grid. The conjunction of energy source and storage type open the door to reshaping the sustainability and robustness of the mains while improving system parameters such as efficiency and fuel consumption. The solution fits existing networks as well as new ones. The study proposes the creation of an accurate optimal sizing procedure for setting the required rating of each type of source. The first step is to model the storage and energy sources by using real experimental results for creating the generic database. Then, data on the mission profile, system constraints, and the minimization target function are inserted. The mission profile is then analyzed to determine the minimum and maximum energy source rating. Next, the real time energy management system controller is used to find the set of solutions for each available energy source and the optimal compatible storage in the revealed band to fulfil the mission task. A Pareto-curve is then plotted to present the optimal findings of the sizing procedure. Ultimately, the main research contribution is the far more accurate sizing results. A case study shows that relying on the standard method leads to noncompliance of sizing constraints, while the proposed procedure leads to fulfilling the mission successfully. First, by utilizing experimentally based energy and a storage unit. Second, by using the same real time energy management system controller in the sizing procedure.