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Abstract The paper explores the use of the magnetic control strategy for the output power regulation of an LCC‐S compensated inductive wireless power transfer system. The magnetic control is implemented through a controlled variable inductor whose magnetization state is actively regulated by an auxiliary DC–DC converter. The principles for the design and regulation of the system are discussed, and the experimental setup for the validation of the regulation method is implemented. Several measurement results highlight the effectiveness and potential improvements of the magnetic control strategy for inductive wireless power transfer systems.

Abstract Increasing the power rating of electric vehicles (EV) fast charging stations to reduce charging times is considered critical to accelerate the adoption of electric vehicles. Besides increasing the power, other drivers pushing the development of EV fast chargers include the improvement of efficiency and reliability. Partial power converters (PPC) have emerged as an interesting option for some of the power converter stages in fast charging stations due to their potential to increase efficiency and power rating. However, some PPCs operate as switched autotransformers by using high frequency (HF) isolation transformers but without providing galvanic isolation. This is a drawback due to cost, size and losses introduced by the transformer. This paper presents a transformerless DC–DC Type I step‐up PPC for a DC–DC regulation converter for EV fast charging stations. The proposed converter replaces the transformer commonly used in Type I PPC by an impedance network, resulting in a more efficient, cheaper, and less complex converter option. This concept is verified through simulations and experimentally validated with a laboratory prototype.

Abstract Wireless power transfer (WPT) is a promising technology and has attracted many researchers’ attention due to its inherent advantages such as reliability, safety, flexibility, and low maintenance costs. For WPT systems, the output voltage varies according to the variable loads and the coupling coefficient conditions, affecting system stability and efficiency. In this regard, this study is concerned with the tracking control problem of WPT systems based on fuzzy supervisory proportional–integral (PI) controller and a phase shift modulation technique, which is for the first time proposed by this paper. By introducing appropriate fuzzy rules, the proposed control scheme not only can track the desired output voltage but also has better robust behaviour to deal with the problem of variations of circuit elements and coupling coefficients. That is, the proposed fuzzy supervisory PI control scheme can perform better than the traditional PI controller. Analysis of the designed control method and simulation results validate the superiority of the proposed method over the traditional PI controller in all conditions, which can make it a suitable choice for the applications of electric vehicle charging systems. The analysis is supported by experimental measurements.

This paper proposes an extended DC‐DC converter with high voltage conversion ratio and soft‐switching ability. The proposed converter has active switched‐inductors, switched‐capacitors included in the conventional high gain converter and operates in continuous conduction mode (CCM). Simple auxiliary resonant elements are added on the primary leg of the converter to provide design freedom for soft‐switching operation. The significant merits of the proposed converter are lesser voltage and current stresses, high voltage gain with reduced component count and better efficiency. Additional feature of this converter is soft‐switching operation under different load conditions and duty ratios without considerably increasing stresses. The zero voltage switching (ZVS) turn‐on operation is obtained for all switching devices. Therefore, switching power losses are minimized greatly. This paper presents the description, principles of operation and steady state analysis in comparison with the existing high gain converters. The theoretical analysis is verified with a 350 W prototype operated at input is 20 V and output is 220 V. The overall efficiency achieved is 96.7%. The obtained results confirm ZVZCS operation at full load. [ABSTRACT FROM AUTHOR]

The most challenging aspect of utilizing model predictive controllers (MPCs), particularly those involving power electronic applications, is the extraction of a model that accurately represents the behavior of the studied system. Concerning the use of power electronic applications, as long as an MPC is used, adjusting the controller parameters brings difficulties. In addition, as the number of elements increases, it becomes harder to get the best control law out of the model. To do away with the need for model extraction, this study presents an offline data‐driven approach in conjunction with the MPC that can optimally adjust the MPC parameters based on the iterative feedback tuning (IFT) algorithm called the iterative feedback predictive controller (IFPC). The proposed method eliminates concerns regarding selecting an optimal number of algorithm iterations, thereby reducing operating costs, by introducing a modified IFT called feedback‐based IFPC (FIFPC) while simultaneously achieving optimal MPC parameters. The proposed method is applied to a constant voltage load (CVL) connected less‐than‐ideal buck converter, that is, one with perturbed filter elements and variable loads. A robust stability analysis (RSA) is performed under normal operating conditions to investigate the robustness behavior of the proposed controller. Simulation studies are presented to evaluate the proposed controller under different scenarios, such as step and abrupt load changes and measurement noise, compared with the well‐known model‐based and data‐enabled predictive controller (DeePC) approaches in the MATLAB/Simulink environment. [ABSTRACT FROM AUTHOR]

Direct current microgrid (DCMG) clusters are gaining popularity in power systems due to their simplicity and high efficiency. However, DCMG clusters are susceptible to minor disturbances due to low system inertia. This paper proposes a method to enhance the small‐signal stability of a DCMG cluster by optimizing the main control parameters of the system. This paper presents a small‐signal state‐space model of a DCMG cluster system at the system level, considering a multi‐bus network topology. Then, the control parameters that significantly affect the small‐signal stability of the DCMG are selected using the participation factor method. To enhance the system damping, the Pareto‐optimal frontier of the bi‐objective problem was determined using the elite non‐dominated sorting genetic algorithm (NSGA‐II). The optimal compromise is determined by using the fuzzy membership function method to extract it from the generated Pareto optimal front. The proposed method has been verified on a three‐sub DCMG test system with droop control. [ABSTRACT FROM AUTHOR]

Environmental issues and the global need to increase economically sustainable access to electricity addressed and boosted scientific research and use of Distributed Energy Resources, such as solar Photovoltaic (PV). Multi‐port power converters can be of great interest for a compact and efficient interface between PV, storage units, and DC loads. The Triple Active Bridge (TAB) shows interesting advantages in terms of isolation and Zero Voltage Switching capabilities over wide load and input voltage ranges. This work aims to develop a TAB prototype for a NanoGrid (NG) application, analyzing the possibility of a direct interface of PV modules, storage units, and DC loads, without the use of intermediate conversion stages. The TAB prototype uses Gallium Nitride devices, and an evaluation of the overall efficiency is provided, useful to compare with other isolated three‐port converters. Through an analytical approach, a TAB has been sized and optimized to meet specific application requirements. MATLAB/Simulink simulations have been done for the sizing validation and the control strategy design. A prototype has been developed and experimental measurements have been compared with simulation results. The TAB is proposed as a key element of DC NGs, but applications of interest are also automotive, More Electric Aircraft, and naval applications. [ABSTRACT FROM AUTHOR]

The presented work discusses issues related to the use of modern multiphase topologies of Dual Active Bridge (DAB)‐type converters. Converters of this type are widely used in most DC microgrid applications. The introduction emphasizes a comparative analysis between single‐phase and multi‐phase DAB topologies within high‐power DC microgrids, delving into their respective advantages, drawbacks, design procedures, and considerations based on the latest knowledge. The publication explores the comparison and selection of viable topologies for deployment in high‐power and high‐efficiency DC microgrids. The unified method of controlling 1‐phase and multi‐phase DAB converters was proposed in this design, simplifying the issues of DC microgrid control. All topologies were tested on the same controller concept. The study performs laboratory investigation of DAB 1‐phase and 3‐phase: Star–Star, and Star–Delta topologies. Attention was paid to maintaining uniform operating conditions of the system, contrary to studies known from the literature, all tests were carried out on the same laboratory stand and the same magnetic components in different configurations. Analytical and laboratory analyses of the Zero Voltage Switching (ZVS) region were performed, accounting for non‐linear phenomena. Based on these findings, an assessment of the system's performance in soft switching was carried out. The presented results were implemented in a simulation model and subsequently validated through tests on a constructed laboratory setup to ensure the proper operation of the system. This work meticulously presents and discusses variations in efficiency, dynamic response, phase current harmonic distribution, phase shift distribution, ZVS switching region, and more among the examined topologies. To ensure a fair comparison, the converter configuration for both simulation and laboratory models utilized identical components across all configurations. [ABSTRACT FROM AUTHOR]

Due to galvanic isolation, bidirectional power transmission and extensive voltage adjustment, dual active bridge (DAB) exerts significant interface between renewable sources and electric vehicle (EV) storage port. However, for DAB operations, under light load or high voltage gain conditions, minimization of root‐mean‐square (RMS) current (MRMS) causes a restricted soft‐switching range. With variations of output power and operation modes, maintenance for all switches ZVS operation is difficult to maintain. Therefore, here, a segmented‐region optimum modulation (SROM) scheme based on extended‐phase‐shift (EPS) control is proposed to solve the aforementioned problems and solve complicated coupled relationship among different optimization methods. Firstly, based on voltage gain and transmission power, all EPS modes are divided clearly. Then, for switching loss reduction, fully‐power‐range ZVS (FZVS) is realized through transitions among EPS modes. Thirdly, either all semiconductors ZVS or not, most suitable optimization method is selected for different EPS regions by SROM. Further, to establish accurate boundaries among these optimization methods, relationship between inner phase‐shift ratio D1 and outer phase‐shift ratio D2 are quantified by unified parameter algorithm with unified parameter m. Therefore, for any EPS modes, efficiency is promoted comprehensively. A DAB‐based prototype is established and experimental results verify correctness and effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

Isolated multiple port DC/DC converters, such as the Multiple Active Bridge (MAB) converter, have many recent applications, such as interconnection between grids, isolated uninterruptible power sources (UPSs) and electric vehicle chargers. MAB converter is an attractive solution from the point of view of the hardware because of its symmetry and its capability to be extended to any number of bridges with a moderate number of components. However, the main challenge of this converter is the control method in order to achieve independent control between the different ports and to minimize recirculating currents. For that reason, three‐port power converters have been already investigated, but many improvements can be done for a larger number of ports. This paper proposes to use a Fourier decomposition for the main power signals to separate their real and imaginary parts. As the signals work at the switching frequency, this decomposition is developed with analog electronics. Based on that, a general control method for regulating the power at the different ports is presented using the first harmonic component, which delivers most of the power. In this proposal, two nested control loops ensure accuracy for the DC power flow. Simulation and experimental results validate the proposal. [ABSTRACT FROM AUTHOR]

This paper proposes a new DC–DC bipolar resonance converter that combines a dual‐active‐bridge and a multi‐port resonance Buck‐Boost converter. This structure uses a resonance network between the input and output ports, which has the following advantages: it creates a constant current supply in the open‐loop mode; it keeps the current phase of the output ports constant under different loads; and it allows reversing the power from any output port by adjusting the phase shift of its switches, if the converter is connected to a DC microgrid. In this way, power can be exchanged among each of the output ports and input ports. The advantages of this converter are bidirectional power exchange, power exchange between output ports, soft switching, high efficiency, integration of transformer parasitic elements, and the modular capability to connect multiple resources at the input. Furthermore, the proposed structure of the bipolar converter has been implemented for verification purposes, and its results are presented in three modes: open loop, voltage control, and current control. Additionally, the results of different modes of power sharing and their bidirectionally are shown. [ABSTRACT FROM AUTHOR]

In electric vehicles (EVs), the low voltage dc‐dc converter (LDC) with synchronous rectifier switches (SRs) can be used to reduce conduction loss caused by the high load current and improve the efficiency. Therefore, it is important to design a proper turn‐on time of SRs. As a popular driving strategy for the SRs, the drain–source voltage across the SRs is sensed to generate the gate driving signal. However, when LLC dc–dc converter operates at O mode, there will be a voltage ringing across the SRs. If the ringing voltage reaches to the threshold voltage −Vth,on, it would make SRs turn‐on early and results in abnormally working of the converter. The novelty and contribution of this paper lie in: (1) elaborating on the voltage ringing across the SRs, (2) the accurate ringing model is established during O mode, and (3) a simple, lossless, and low‐cost filter circuit is used to solve the negative effect of the ringing voltage for LLC converter at high load current. A 1.26 kW experimental prototype with ≈250–430 V wide input voltage and ≈9–16 V wide output voltage is implemented, 96.7% peak efficiency and 96% full load efficiency are achieved with a 3.12 kW/L power density. The theoretical analysis has been validated by the simulated and experimental results, and the SR LLC dc–dc converter with the SR works efficiently and reliably with the proposed solution at a high load current. [ABSTRACT FROM AUTHOR]

Three‐coil inductive power transfer (IPT) charging system can not only achieve inherent constant current (CC) to constant voltage (CV) transition but also tolerate load open‐circuit. However, due to the cross‐coupling between the auxiliary coil and the receiver coil, the output voltage in CV mode may deviate from the CV voltage significantly, which makes the design freedom of the three‐coil coupler low. By replacing the auxiliary coil with a transformer, an improved auxiliary circuit is proposed in this paper to address the cross‐coupling issue and to increase the design freedom of the loosely coupled transformer (LCT). The improved auxiliary circuit can achieve load short‐circuit and open‐circuit protection. Besides, the optimization design of LCT is easy to achieve by load impedance matching. The operating principle and parameters design of the improved auxiliary circuit are discussed. A 1 kW experimental prototype is built to verify the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

LLC resonant converters are widely adopted in many different industrial applications due to their high efficiency operation. To further improve LLC resonant converters' efficiency, the secondary unregulated diode rectifier is replaced by the synchronous rectifier (SR). In many applications, LLC converter is designed to operate at resonant frequency to maximize the system efficiency and act as a DC transformer (DCX). The SR driving signal is set as the same as the primary driving signal to work in an open‐loop mode. However, the resonant frequency will deviate due to the tolerance, working environment, and ageing effect of circuit components, which will lead to the degradation of the system efficiency and output voltage variation. Unfortunately, most of the existing techniques cannot be simply adopted in SR LLC DCX. Therefore, an adaptive SR driving strategy that can compensate the circuit components' variations is necessary for SR LLC DCX. Inan adaptive SR strategy based on the constant voltage gain characteristic at resonant frequency point is proposed. The proposed strategy is applicable for all different scenarios with easy implementation and low cost. [ABSTRACT FROM AUTHOR]

In this paper, a reduced‐switch‐count two‐phase interleaved LLC converter with precise current balancing is proposed by using switching‐control‐capacitor (SCC) technology. Compared with the conventional SCC‐LLC converter, the proposed two‐phase SCC‐LLC converter reduces the switch count with the SCC circuits, and achieves excellent current sharing under all the tolerance conditions between the two‐phase resonant elements. In the proposed converter, the SCC circuit is only used in the first phase. The design of the SCC circuit parameters is analyzed to reduce the voltage stress of the SCC circuit and to ensure that two‐phase currents are balancing with large tolerance of resonant elements. A 2.16‐kW GaN‐based two‐phase interleaved SCC‐LLC converter prototype is established for data center application, and the experimental results show that the 98.1% peak efficiency, the 97.6% full load efficiency, and higher than 96% efficiency at the wide range from 3‐A to 40‐A load current are achieved. The precise current sharing lower than 1% is achieved by using a cheap ceramic capacitor with high tolerance, which validates the performance of the converter. [ABSTRACT FROM AUTHOR]

In the inductive power transfer (IPT) system, using multiple coil branches instead of a whole large coil can effectively solve the thickness problem and save space. In that case, there are small parameter differences in mutual inductance and self‐inductance between the coil branches in parallel. These differences are amplified in high‐frequency IPT systems, resulting in different currents flowing through the different coil branches. The current unbalance will create many hazards. Therefore, this paper analyzes the key factors that cause current to unbalance and studies the equivalent circuit model of an inductive power transfer system with secondary multiple parallel branches. Moreover, this paper designs the compensation circuit and studies two kinds of current balance methods. Furthermore, the parameter design criteria are detailed to obtain a nearly ideal current balance effect. The characteristic analysis, parameter design, and verification are described in detail. [ABSTRACT FROM AUTHOR]

This paper investigates the stability and reliability analysis of a non‐isolated high‐gain DC‐DC converter. The proposed DC‐DC converter produces a high gain output voltage with a lower duty ratio and reduced voltage stress on the semiconductor switch. A reliability analysis is performed to predict the failure rate and lifetime of the individual components using the military handbook (MIL‐HDBK‐217F). A state space equation and small signal modeling of the proposed converter are derived to elucidate the performance of the proposed converter through stability analysis. A closed‐loop using PID controller is incorporated to attain the constant regulated output voltage during sudden parameter changes. The validation of the closed‐loop using the PID controller is verified with the wide range of variations in the different parameters, such as input voltage, load value, and reference voltage value. The laboratory‐based prototype is developed for the proposed converter and validated the performance with 250 W. The power density and efficiency of the proposed converter are 1.360 kW/L and 93%, respectively. [ABSTRACT FROM AUTHOR]

The integration of supercapacitors as hybrid energy storage systems in electric vehicles has attracted the attention of many researchers and has been considered as a promising solution. Bidirectional DC/DC converters (BDDCs) play a fundamental role in HESS, as they manage the power flow by controlling currents and regulating the DC bus voltage. However, they encounter the challenge of uncertainties and high fluctuation power loads, necessitating the fast dynamics, stability, and high robustness of the controller. This paper proposes a novel hybrid proportional–integral and backstepping cascade controller to regulate the DC‐bus voltage under uncertainties and load variations, and to control the current references of the on‐boarded sources. To confirm the asymptotic stability of the whole system, a nonlinear stability analysis is conducted using the Lyapunov theorem. A power management strategy is applied to distribute the power loads and generate reference currents for the BDDCs controller. Simulations results under various driving cycles using MATLAB/Simulink demonstrate the superiority of the proposed controller compared to conventional proportional–integral and backstepping controllers. A real‐time controller‐hardware‐in‐the‐loop test bench is developed to validate the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

Most high‐gain step‐up dc‐dc structures operate with a limited duty cycle and suffer from a high component count, limiting their application. This paper addresses these problems by proposing a new step‐up dc‐dc converter that provides a high conversion ratio with few elements. Two coupled inductors are used instead of conventional voltage multiplier cells to improve the gain without excessive components. The topology includes one switch whose duty cycle is not limited and can vary between zero and one according to the output voltage condition. It has been placed on the low‐voltage side of the converter that encounters low‐voltage stress. It is selected from low‐voltage rating switches with small on‐resistance, which reduces the conduction loss of the switch and improves the efficiency. High boost factor, high efficiency, reasonable component counts, improved gain‐to‐element ratio, and low voltage stress on the switch distinguishe the converter from their counterparts. The topology also benefits from the common‐ground feature. However, its input current waveform is pulsating. This article describes the theory and operation principle of the topology in detail. Experimental results are represented to evaluate the converter's performance and operation. In this case, a 240 W prototype has been designed and fabricated. Results confirm the above claims. [ABSTRACT FROM AUTHOR]

Here, a high gain DC–DC converter which is based on switched capacitor (SC) and switched LCL (SLCL) cells is presented. The diode employed in the classical passive switched inductor (SI) cell is replaced by a capacitor in the proposed SLCL cell to achieve higher voltage gain. Two switches—one each in the positive and negative DC rails of the supply are employed to charge and discharge the inductors of SLCL cells. A generic structure comprising of N and M number of SLCL cells in the positive and negative DC rails respectively along with K number of SC cells is presented. To validate the proposed gain extension concept, a two‐switch based converter comprising of 2 SLCL and 1 SC cells is synthesized and its operation is described in detail. The voltage gain expression of the proposed SLCL‐SC converter is derived. Experimental results are obtained from a 25 to 380 V prototype converter which operates at a full‐load efficiency of 94.22% at 200 W. Since the switches employed in the proposed converter are operated at a moderate and safe duty ratio of D = 0.51, the voltage stress on the switches is about 25% of the output voltage while the diodes are subjected to even lesser voltage stress levels of only one‐fifth of the output voltage. The main salient features of the proposed topology are its (i) modular structure, (ii) ability to provide higher voltage gain values at lower duty ratios (iii) reduced voltage stress on the semiconductor devices and (iv) reduced conduction losses due to the replacement of diodes with capacitors in SLCL cells. [ABSTRACT FROM AUTHOR]

This paper introduces a novel approach for designing a Wireless Power Transfer (WPT) system with LCC‐S compensation. Since WPT systems operate under resonant conditions, even small deviations of the components from the nominal values can result in a significant reduction of the power transferred to the load, and in an increment of the circulating currents, reducing the system efficiency. The design techniques available today in the literature provide a unique combination of passive components capable of transferring a certain power to the load. This is a limitation, because, in practice, there are several combinations that allow reaching the desired output power, but they are usually neglected because they are extremely difficult to compute analytically. For this reason, in this paper, the authors present an innovative design procedure that enables, through a Genetic Algorithm, the identification of multiple feasible combinations of the LCC‐S components capable of achieving the desired output power. Moreover, the authors evaluate the effects of the component tolerances on the output power to determine which combinations are more robust to component variations. This task is performed by calculating the probability that a particular combination yields the desired output power, once the tolerances have been considered, following a Monte Carlo approach. This information is utilized to decide whether it is possible to reduce the component quality (worsening the tolerance) without affecting the performance. Finally, an optimal solution granting both low‐cost and robustness against component tolerances can be individuated. The proposed design procedure is applied to a case study and validated experimentally. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) is a promising technology and has attracted many researchers' attention due to its inherent advantages such as reliability, safety, flexibility, and low maintenance costs. For WPT systems, the output voltage varies according to the variable loads and the coupling coefficient conditions, affecting system stability and efficiency. In this regard, this study is concerned with the tracking control problem of WPT systems based on fuzzy supervisory proportional–integral (PI) controller and a phase shift modulation technique, which is for the first time proposed by this paper. By introducing appropriate fuzzy rules, the proposed control scheme not only can track the desired output voltage but also has better robust behaviour to deal with the problem of variations of circuit elements and coupling coefficients. That is, the proposed fuzzy supervisory PI control scheme can perform better than the traditional PI controller. Analysis of the designed control method and simulation results validate the superiority of the proposed method over the traditional PI controller in all conditions, which can make it a suitable choice for the applications of electric vehicle charging systems. The analysis is supported by experimental measurements. [ABSTRACT FROM AUTHOR]

The paper explores the use of the magnetic control strategy for the output power regulation of an LCC‐S compensated inductive wireless power transfer system. The magnetic control is implemented through a controlled variable inductor whose magnetization state is actively regulated by an auxiliary DC–DC converter. The principles for the design and regulation of the system are discussed, and the experimental setup for the validation of the regulation method is implemented. Several measurement results highlight the effectiveness and potential improvements of the magnetic control strategy for inductive wireless power transfer systems. [ABSTRACT FROM AUTHOR]

High efficiency and unity power factor (PF) are the most important requirements of a wireless charger system simultaneous with the output voltage regulation. Achieving all above‐mentioned criteria in a wide range of the load is challenging in the system. This paper presents a novel control approach applied to series‐series wireless power transmission converter by using a dual‐function compensator to achieve unity PF and maximum efficiency during the constant power‐constant voltage (CP‐CV) charging scenarios. A semi‐active rectifier with impedance matching capability along with a switch‐controlled capacitor constitutes the dual‐function compensator on the secondary side. Meanwhile, the primary side inverter executes the CP‐CV charging scenario for the battery with various charging characteristics at a fixed‐switching frequency. Besides that, all secondary side switches experience soft switching condition throughout the battery charging. Finally, a prototype with a power of 200 W and roughly regulated efficiency of 90% is presented in order to verify the proposed control method. [ABSTRACT FROM AUTHOR]

Increasing the power rating of electric vehicles (EV) fast charging stations to reduce charging times is considered critical to accelerate the adoption of electric vehicles. Besides increasing the power, other drivers pushing the development of EV fast chargers include the improvement of efficiency and reliability. Partial power converters (PPC) have emerged as an interesting option for some of the power converter stages in fast charging stations due to their potential to increase efficiency and power rating. However, some PPCs operate as switched autotransformers by using high frequency (HF) isolation transformers but without providing galvanic isolation. This is a drawback due to cost, size and losses introduced by the transformer. This paper presents a transformerless DC–DC Type I step‐up PPC for a DC–DC regulation converter for EV fast charging stations. The proposed converter replaces the transformer commonly used in Type I PPC by an impedance network, resulting in a more efficient, cheaper, and less complex converter option. This concept is verified through simulations and experimentally validated with a laboratory prototype. [ABSTRACT FROM AUTHOR]

Abstract This article presents the new hybrid switched‐capacitor (SC)‐based transformerless DC–DC converter with a high step‐up capability and common ground features. The proposed hybrid SC‐based converter provides low voltage stress across semiconductor devices to utilize MOSFETs with lower Rdson and low voltage ratings. In addition, the diodes in SC cells with low voltage stress can reduce the reverse recovery power loss of the converter. Thus, the overall efficiency of the proposed hybrid SC‐based converter can be increased. The converter circuit, operating principle, and design guidelines of the proposed hybrid SC‐based converter are discussed. To confirm the performance of the proposed hybrid SC‐based converter, a detailed comparison study with the conventional hybrid SC converter is also presented. Finally, a laboratory prototype with 200 W and 25 to 200 V is set up to verify the effectiveness of the proposed hybrid SC‐based converter.

Abstract This paper proposes, a novel soft‐switching bidirectional direct current to direct current (DC–DC) converter based on switched‐capacitor and coupled‐inductor. The proposed converter has a simple structure and utilizes four switches and a three‐winding coupled inductor and can achieve a high voltage conversion ratio in both step‐up/step‐down operations. By employing the switched‐capacitor technique, voltage stress across the power switches is low and therefore low voltage rating switches can be adopted to reduce the losses of their conduction. Soft‐switching characteristic of the proposed converter reduces the switching loss of active power switches and raises the conversion efficiency. This paper presents theoretical analysis for all operating modes of the converter, voltage conversion ratio, voltage and current stresses of all power switches. Finally, to test the validity of theoretical results and demonstrate the performance of the converter, experimental results are provided.

Abstract This paper presents a novel algorithm for fault diagnosis and fault tolerant control of interleaved boost converters (IBCs) in the presence of single or double simultaneous open‐circuit faults (OCFs) in power switches. An innovative diagnosis signal (recorded by a cheap current sensor) will be introduced whose waveform mainly depends on the healthy or faulty condition of the converter. Since the diagnosis signal is periodic in the steady‐state operation of the converters, its Fourier Series coefficients, together with the duty cycle of the converter are used as distinguishing features for fault diagnosis of the OCFs in the converter. The well‐known Kalman filter is utilized for robust estimation of the Fourier‐based features. Finally, the modulation of the remaining healthy phases is rearranged in a way that the pre‐fault performance recovers. The proposed algorithm is verified in a laboratory four‐phase IBC setup in which the experimental results show its satisfactory performance. Also, the structure of the proposed method is straightforward and can be implemented in the same microcontroller which is used for voltage and current regulation of the converter.

Abstract High‐gain converters play a vital role in all industrial applications such as automobiles, motor drives, renewable energy systems, and railway transportation sectors. The conventional converters have low gain owing to high‐voltage stress on active MOSFET, diode and low efficiency related with high operating pulse ratio. To overcome the limitations associated with the conventional converters, this study proposes a non‐isolated configuration of multiport quasi‐resonant converter (MP‐QRC) with high gain. The proposed MP‐QRC has the merits of high‐voltage gain, reduced number of components, minimum conduction losses, realization of soft switching in the devices and improved reliability. Moreover, the proposed converter is scalable and can serve as a good candidate in microgrid environment where the integration of more than one input is essential. In this paper, first a comprehensive analysis of various operation modes and design constraints are presented. Further, the study is supported with a reliability evaluation of proposed converter based on component failure. Also, the futuristic behaviour of MP‐QRC under continuous conduction mode as a function of operational and environmental variables is investigated to ascertain the reliability. The steady‐state operation of the converter is demonstrated for off‐board electric vehilce (EV) charging using MATLAB/SIMULINK and experiments performed on a 300‐W test rig.

Abstract Integration of photovoltaic panels (PV) with electric vehicle (EV) charging stations could reduce the grid impact and carbon footprint from the extensive fast and ultra‐fast charging. This paper introduces a decoupled quad‐active‐bridge converter (QAB) with multi‐directional power flow capability, which can integrate PV, energy storage (ES), grid, and EV in a charging station and rule the power among them. As the number of ports increases in the multiple‐active‐bridge converter, the complexity of control increases exponentially because of power decoupling. For the QAB, by tuning one port in series with LC units, the decoupling is achieved between the other three ports, reducing the control difficulty significantly. Further, the resonance decoupling method is extended to the n‐port converter. For different power flows, the system automatically switches between different resonance modes to form higher‐efficiency power flow channels. Three operating modes with decoupled closed‐loop control methods have been constructed for the QAB to be suitable for future charging stations: (1) Charging mode: PV, ES, and grid coordinate with each other to provide incessant and stable charging for EV. (2) Electricity sales mode: Gird is supplied by PV, ES, and EV flexibly. (3) Under no load, PV power is stored locally. Experimental waveforms were presented by a 1‐kW prototype, verifying the effectiveness of power decoupling and the feasibility of the three operating modes.

Abstract The utilization of switched inductors, involving parallel charging and series discharging of inductors, is extensively embraced in diverse DC–DC converters for attaining high voltage gain; nevertheless, the stress on switch voltage and diode current escalates considerably with an increased count of inductors integrated into the switched inductors network. In the classical multistage switched inductor converter, the switch voltage aligns with the output voltage, and the diode experiences a high current as the number of stages increases. This research recommends a DC–DC multistage converter for energy conversion and high voltage gain with low stress. In this paper, a novel multistage switched inductor converter is introduced and designed to attain higher voltage gain while mitigating the stresses on switch voltage and diode current. The proposed circuit is created by replacing the standard multistage switched inductor converter's possible diodes with power switches. All of the switching devices are connected in such a way that the output voltage and input current are shared by all of the switches and diodes, respectively. As a consequence, the voltage stress on switches and the current stress on diodes are comparatively low, resulting in a high efficiency compared to a typical multistage switched inductor converter. It's interesting to note that the proposed converter and a typical multistage switched inductor converter both require the same amount of components. Different operation modes, analysis, a non‐ideal model, and a comparison of the suggested and recently constructed converters are discussed. The effectiveness and performance of the circuit are validated experimentally.

Abstract This paper proposed a new two‐phase high step‐down DC–DC converter is proposed. This converter is derived from the two‐phase series‐capacitor converter. The proposed converter replaces the series capacitor with a new structure that integrates Valley‐Fill circuit and coupled‐inductors concepts. This replacement can improve the voltage gain of the converter as well as a considerable reduction of diodes voltage stress. The proposed structure implements a dual‐phase buck using a single magnetic element. Also, the proposed structure inherently limits the voltage spikes due to the leakage inductance of coupled inductors without any additional clamp circuit. The proposed converter is analyzed, and design guidelines are provided. A 300–24 V prototype converter is implemented to justify the validity of circuit operation and the theoretical analysis.

Abstract Light is a popular choice as an indoor energy source for Internet of Things (IoT) end devices. However, indoor light sources are intermittent, which can disrupt the operation of IoT end devices, potentially leading to safety concerns or inaccurate data. Therefore, there is a growing need to develop a long‐duration power supply for IoT end devices. The energy from ambient light is harnessed to charge a supercapacitor through an energy manager chip. This supercapacitor serves as the power source for IoT nodes when the ambient light is unavailable. Nevertheless, as the voltage of the supercapacitor drops below the operating threshold, the IoT end node will eventually shut down. This paper proposes a circuit that utilizes a Joule Thief circuit, booster converter, and capacitor stack‐up circuit to extract the remaining energy from the supercapacitor and boost the voltage, thereby extending the operational lifespan of IoT end nodes. Additionally, capacitor stack‐up circuits significantly enhance charging efficiency. PSpice design and simulations confirm circuit feasibility. High‐efficiency charging and long‐duration IoT nodes suggest replacing traditional batteries with supercapacitors, reducing environmental impact.

Abstract In this paper, a new high step‐up DC–DC converter is presented. The presence of an inductor at converter input reduces input current ripple. Furthermore, a coupled inductor with a voltage multiplier cell is also implemented to increase the voltage gain of the converter. The stored energy in leakage inductance of coupled inductor is recycled by a clamp circuit which increases efficiency and clamps voltage on power switch. The power switch is turned on and off under soft switching condition. The soft switching is also applied to auxiliary switch. All diodes are turned off under zero current condition which causes reverse recovery problem to be alleviated. A very low current flows through auxiliary components in a very short time. Therefore, a very low conduction loss is added to the converter by an auxiliary circuit. Soft switching condition is almost independent of specifications of circuit, especially the output power. Steady‐state analysis of the proposed converter is discussed. Finally, to verify the performance and validation of the proposed converter, laboratory results for a prototype with input voltage 30 V, output voltage 240 V, output power 220 W and switching frequency 50 kHz are presented and the results are discussed. The efficiency of the prototype converter at nominal power is 96%.

Abstract One of the early design decisions for DC‐DC converters is the choice of an appropriate magnetic core material. Powder cores in particular are suitable due to their saturation flux density of up to 1.5 T. However, high DC currents constitutes a significant problem since the winding cross‐section rises with the current, which consequently increases AC losses due to skin effects. Another challenge is the reduction of winding layers to decrease proximity losses. This paper presents an improved single‐layer winding design procedure for DC‐DC converter powder cores. The procedure determines the optimum number of parallel cores and stacks. This way, the procedure enables a predefined maximum wire cross‐section for copper loss optimisation and single‐layer winding. The introduced approach defines the optimum switching frequency as a trade‐off between core loss and core volume. Finally, experimental tests with two setups validate 27 kW DC‐DC converters and hence the design procedure using Si‐IGBTs and SiC‐MOSFETs. The results demonstrate that SiC‐MOSFETs reduce core volume by a factor of 3 compared to Si‐IGBTs. Further, the SiC setup reaches high efficiencies of up to 98.53% compared to 98.17% for the Si‐based converter.

Abstract This article presents a novel high step up converter based on the active switch inductor (ASL) technique for renewable energy source applications. The coupled inductor technique provides an opportunity to increase the gain. The proposed converter exploited the leakage inductors to provide zero current switching (ZCS) turn‐on for both switches. Therefore, there is no need for an auxiliary circuit, which simplifies the structure. Also, all diodes turn off under ZCS, which eliminates the reverse recovery problem and results in reduced switching losses. The energy of the leakage inductor is recycled, and the voltage spike on the switches is limited. In addition, all semiconductor voltage stresses are clamped below the output voltage. Hence, components with lower on‐resistance can be utilized to reduce conduction loss. Because of the reduction in power loss, the efficiency rises to 97.2% at 250 W output power. It also benefits from the current sharing of the interleaved structure. The operating principles, design considerations, and comparison to other topologies are discussed. To verify the effectiveness of the proposed converter, a prototype converter with 250 W of output power, 50 V of input voltage, 500 V of output voltage, and 100 kHz of switching frequency is implemented.

This paper proposes, a novel soft‐switching bidirectional direct current to direct current (DC–DC) converter based on switched‐capacitor and coupled‐inductor. The proposed converter has a simple structure and utilizes four switches and a three‐winding coupled inductor and can achieve a high voltage conversion ratio in both step‐up/step‐down operations. By employing the switched‐capacitor technique, voltage stress across the power switches is low and therefore low voltage rating switches can be adopted to reduce the losses of their conduction. Soft‐switching characteristic of the proposed converter reduces the switching loss of active power switches and raises the conversion efficiency. This paper presents theoretical analysis for all operating modes of the converter, voltage conversion ratio, voltage and current stresses of all power switches. Finally, to test the validity of theoretical results and demonstrate the performance of the converter, experimental results are provided. [ABSTRACT FROM AUTHOR]

High‐gain converters play a vital role in all industrial applications such as automobiles, motor drives, renewable energy systems, and railway transportation sectors. The conventional converters have low gain owing to high‐voltage stress on active MOSFET, diode and low efficiency related with high operating pulse ratio. To overcome the limitations associated with the conventional converters, this study proposes a non‐isolated configuration of multiport quasi‐resonant converter (MP‐QRC) with high gain. The proposed MP‐QRC has the merits of high‐voltage gain, reduced number of components, minimum conduction losses, realization of soft switching in the devices and improved reliability. Moreover, the proposed converter is scalable and can serve as a good candidate in microgrid environment where the integration of more than one input is essential. In this paper, first a comprehensive analysis of various operation modes and design constraints are presented. Further, the study is supported with a reliability evaluation of proposed converter based on component failure. Also, the futuristic behaviour of MP‐QRC under continuous conduction mode as a function of operational and environmental variables is investigated to ascertain the reliability. The steady‐state operation of the converter is demonstrated for off‐board electric vehilce (EV) charging using MATLAB/SIMULINK and experiments performed on a 300‐W test rig. [ABSTRACT FROM AUTHOR]

This paper presents a novel algorithm for fault diagnosis and fault tolerant control of interleaved boost converters (IBCs) in the presence of single or double simultaneous open‐circuit faults (OCFs) in power switches. An innovative diagnosis signal (recorded by a cheap current sensor) will be introduced whose waveform mainly depends on the healthy or faulty condition of the converter. Since the diagnosis signal is periodic in the steady‐state operation of the converters, its Fourier Series coefficients, together with the duty cycle of the converter are used as distinguishing features for fault diagnosis of the OCFs in the converter. The well‐known Kalman filter is utilized for robust estimation of the Fourier‐based features. Finally, the modulation of the remaining healthy phases is rearranged in a way that the pre‐fault performance recovers. The proposed algorithm is verified in a laboratory four‐phase IBC setup in which the experimental results show its satisfactory performance. Also, the structure of the proposed method is straightforward and can be implemented in the same microcontroller which is used for voltage and current regulation of the converter. [ABSTRACT FROM AUTHOR]

Light is a popular choice as an indoor energy source for Internet of Things (IoT) end devices. However, indoor light sources are intermittent, which can disrupt the operation of IoT end devices, potentially leading to safety concerns or inaccurate data. Therefore, there is a growing need to develop a long‐duration power supply for IoT end devices. The energy from ambient light is harnessed to charge a supercapacitor through an energy manager chip. This supercapacitor serves as the power source for IoT nodes when the ambient light is unavailable. Nevertheless, as the voltage of the supercapacitor drops below the operating threshold, the IoT end node will eventually shut down. This paper proposes a circuit that utilizes a Joule Thief circuit, booster converter, and capacitor stack‐up circuit to extract the remaining energy from the supercapacitor and boost the voltage, thereby extending the operational lifespan of IoT end nodes. Additionally, capacitor stack‐up circuits significantly enhance charging efficiency. PSpice design and simulations confirm circuit feasibility. High‐efficiency charging and long‐duration IoT nodes suggest replacing traditional batteries with supercapacitors, reducing environmental impact. [ABSTRACT FROM AUTHOR]

Integration of photovoltaic panels (PV) with electric vehicle (EV) charging stations could reduce the grid impact and carbon footprint from the extensive fast and ultra‐fast charging. This paper introduces a decoupled quad‐active‐bridge converter (QAB) with multi‐directional power flow capability, which can integrate PV, energy storage (ES), grid, and EV in a charging station and rule the power among them. As the number of ports increases in the multiple‐active‐bridge converter, the complexity of control increases exponentially because of power decoupling. For the QAB, by tuning one port in series with LC units, the decoupling is achieved between the other three ports, reducing the control difficulty significantly. Further, the resonance decoupling method is extended to the n‐port converter. For different power flows, the system automatically switches between different resonance modes to form higher‐efficiency power flow channels. Three operating modes with decoupled closed‐loop control methods have been constructed for the QAB to be suitable for future charging stations: (1) Charging mode: PV, ES, and grid coordinate with each other to provide incessant and stable charging for EV. (2) Electricity sales mode: Gird is supplied by PV, ES, and EV flexibly. (3) Under no load, PV power is stored locally. Experimental waveforms were presented by a 1‐kW prototype, verifying the effectiveness of power decoupling and the feasibility of the three operating modes. [ABSTRACT FROM AUTHOR]

This paper proposed a new two‐phase high step‐down DC–DC converter is proposed. This converter is derived from the two‐phase series‐capacitor converter. The proposed converter replaces the series capacitor with a new structure that integrates Valley‐Fill circuit and coupled‐inductors concepts. This replacement can improve the voltage gain of the converter as well as a considerable reduction of diodes voltage stress. The proposed structure implements a dual‐phase buck using a single magnetic element. Also, the proposed structure inherently limits the voltage spikes due to the leakage inductance of coupled inductors without any additional clamp circuit. The proposed converter is analyzed, and design guidelines are provided. A 300–24 V prototype converter is implemented to justify the validity of circuit operation and the theoretical analysis. [ABSTRACT FROM AUTHOR]

The utilization of switched inductors, involving parallel charging and series discharging of inductors, is extensively embraced in diverse DC–DC converters for attaining high voltage gain; nevertheless, the stress on switch voltage and diode current escalates considerably with an increased count of inductors integrated into the switched inductors network. In the classical multistage switched inductor converter, the switch voltage aligns with the output voltage, and the diode experiences a high current as the number of stages increases. This research recommends a DC–DC multistage converter for energy conversion and high voltage gain with low stress. In this paper, a novel multistage switched inductor converter is introduced and designed to attain higher voltage gain while mitigating the stresses on switch voltage and diode current. The proposed circuit is created by replacing the standard multistage switched inductor converter's possible diodes with power switches. All of the switching devices are connected in such a way that the output voltage and input current are shared by all of the switches and diodes, respectively. As a consequence, the voltage stress on switches and the current stress on diodes are comparatively low, resulting in a high efficiency compared to a typical multistage switched inductor converter. It's interesting to note that the proposed converter and a typical multistage switched inductor converter both require the same amount of components. Different operation modes, analysis, a non‐ideal model, and a comparison of the suggested and recently constructed converters are discussed. The effectiveness and performance of the circuit are validated experimentally. [ABSTRACT FROM AUTHOR]

In this paper, a new high step‐up DC–DC converter is presented. The presence of an inductor at converter input reduces input current ripple. Furthermore, a coupled inductor with a voltage multiplier cell is also implemented to increase the voltage gain of the converter. The stored energy in leakage inductance of coupled inductor is recycled by a clamp circuit which increases efficiency and clamps voltage on power switch. The power switch is turned on and off under soft switching condition. The soft switching is also applied to auxiliary switch. All diodes are turned off under zero current condition which causes reverse recovery problem to be alleviated. A very low current flows through auxiliary components in a very short time. Therefore, a very low conduction loss is added to the converter by an auxiliary circuit. Soft switching condition is almost independent of specifications of circuit, especially the output power. Steady‐state analysis of the proposed converter is discussed. Finally, to verify the performance and validation of the proposed converter, laboratory results for a prototype with input voltage 30 V, output voltage 240 V, output power 220 W and switching frequency 50 kHz are presented and the results are discussed. The efficiency of the prototype converter at nominal power is 96%. [ABSTRACT FROM AUTHOR]

One of the early design decisions for DC‐DC converters is the choice of an appropriate magnetic core material. Powder cores in particular are suitable due to their saturation flux density of up to 1.5 T. However, high DC currents constitutes a significant problem since the winding cross‐section rises with the current, which consequently increases AC losses due to skin effects. Another challenge is the reduction of winding layers to decrease proximity losses. This paper presents an improved single‐layer winding design procedure for DC‐DC converter powder cores. The procedure determines the optimum number of parallel cores and stacks. This way, the procedure enables a predefined maximum wire cross‐section for copper loss optimisation and single‐layer winding. The introduced approach defines the optimum switching frequency as a trade‐off between core loss and core volume. Finally, experimental tests with two setups validate 27 kW DC‐DC converters and hence the design procedure using Si‐IGBTs and SiC‐MOSFETs. The results demonstrate that SiC‐MOSFETs reduce core volume by a factor of 3 compared to Si‐IGBTs. Further, the SiC setup reaches high efficiencies of up to 98.53% compared to 98.17% for the Si‐based converter. [ABSTRACT FROM AUTHOR]

This article presents a novel high step up converter based on the active switch inductor (ASL) technique for renewable energy source applications. The coupled inductor technique provides an opportunity to increase the gain. The proposed converter exploited the leakage inductors to provide zero current switching (ZCS) turn‐on for both switches. Therefore, there is no need for an auxiliary circuit, which simplifies the structure. Also, all diodes turn off under ZCS, which eliminates the reverse recovery problem and results in reduced switching losses. The energy of the leakage inductor is recycled, and the voltage spike on the switches is limited. In addition, all semiconductor voltage stresses are clamped below the output voltage. Hence, components with lower on‐resistance can be utilized to reduce conduction loss. Because of the reduction in power loss, the efficiency rises to 97.2% at 250 W output power. It also benefits from the current sharing of the interleaved structure. The operating principles, design considerations, and comparison to other topologies are discussed. To verify the effectiveness of the proposed converter, a prototype converter with 250 W of output power, 50 V of input voltage, 500 V of output voltage, and 100 kHz of switching frequency is implemented. [ABSTRACT FROM AUTHOR]

This paper introduces a new approach for analyzing the dynamics of DC–DC converters. Currently, the primary widely accepted method for examining dynamic processes is the Small Signal Analysis technique. However, when applied to modern complex converters, this method poses additional challenges in formulating and solving systems of differential equations. The method proposed in this paper is based on its application to the analysis of dynamic modes of energy functions—Lagrangians. These functions make it possible to define simple criteria to describe the course of dynamic processes, and in the end define an equivalent (approximating) conventional converter identical to the original one with respect to the course of dynamics. If the magnetic and electrical energies in the Lagrangians of both the converters are equal, the outcome is practically identical transient processes. These findings were confirmed by both theoretical analysis and experimentally modelling the dynamics of the initial converter and an equivalent to it in the Matlab–Simscape program. An additional possibility of using the transfer functions of a conventional boost converter for the theoretical analysis of the converters of much greater orders is also discussed. The authors' experiments confirm the correctness of their theoretical conclusions. [ABSTRACT FROM AUTHOR]

Abstract The demand‐side DC electricity‐using equipment and newly integrated renewables are driving the transformation of power distribution and utilization mode. The building system based on DC technology is emerging as a promising option. In the low‐voltage DC building distribution and utilization system (LVDCBDUS), global energy optimization management and operational control arrangement are key components. To obtain exemplary achievements of those, two different DC building energy management system (DC BEMS) integration schemes are investigated according to the respective features and application‐required functions of various system networking structures. Centralized and decentralized control strategies are presented and discussed for buildings with AC–DC transformation and newly built LVDCBDUSs. On this basis, the centralized DC BEMS and operational control strategy are applied to the first multi‐scenario low‐carbon city‐based future building project—Shenzhen IBR Future Complex. The operation data are recorded and analysed. Problems encountered during the implementation are summarized, and requirements of converter equipment, new technologies and marketization are further discussed to promote the high‐quality development of the LVDCBDUS.

Abstract This paper presents a technique to quickly determine the potential maximum power point (MPP) of a photovoltaic system using the duty cycle (D) of the DC/DC converter. The proposed method depends on estimating the open‐circuit voltage (Voc) and short‐circuit current (Isc) values under different operating conditions. It is an adapted version derived from the conventional Perturb and Observe (P&O) algorithm, designed to restrict the search area for the MPP. The working conditions, including temperature variations, irradiance, or both, are simulated in the PSIM environment and experimented with a simulator with parameters satisfied according to the proposed operating conditions. The research objective of this study also involves operating under partially shaded conditions. When comparing the results of this research with those obtained from the traditional P&O method and the Variable Step Size Perturb and Observe (VSSP&O) approach, it becomes evident that the proposed solution excels in terms of both convergence speed and performance, particularly when operating under partial shade conditions. In addition, this study's methods of determining Isc, Voc, and Dmp can be widely applied in low‐voltage and power systems.

Abstract This paper proposes a novel bidirectional DC–DC converter with high voltage conversion ratio and capability of cancelling input current ripple. The proposed converter uses two coupled inductors and switched‐capacitor circuit to increase the voltage conversion ratio. The input current ripple at low voltage side can be eliminated for a pre‐selected duty cycle by adjusting special values of magnetizing inductances of coupled inductors. The input current is divided into two paths of the primary winding of coupled inductors that causes the decrease in the current stresses of switches. The proposed converter has five switches that consist the internal diodes of switches to bring about bidirectional power flow and have boost and buck operations. Here, the proposed topology is analysed in all operating modes and the current and voltage stresses of switches, input current ripple cancelling condition and voltage conversion ratio are calculated. Finally, the accuracy performance of the proposed converter is reconfirmed through EMTDC/PSCAD simulation and experimental results for boost operations.