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The LLC resonant converter is widely recognized as an effective solution for achieving high efficiency in high-frequency operations. This is primarily due to its ability to perform zero-voltage switching (ZVS) on primary switches and zero-current switching (ZCS) on secondary rectifier switches. However, implementing the secondary rectifier of an LLC resonant converter often requires the use of jumpers on the PCB to construct circuit topologies such as the center-tap rectifier (CTR), full-bridge rectifier, and voltage-doubler rectifier (VDR). In conventional VDR configurations, the source voltage of the high-side FET fluctuates according to the switching operation of the primary switch. This fluctuation necessitates auxiliary windings or bootstrap circuits to provide a floating voltage source, adding significant complexity to gate drive circuits in high-power-density applications. This complexity poses a major barrier to the practical adoption of VDRs. To address these challenges, this paper proposes a novel rectification circuit based on the VDR topology, specifically designed for LLC resonant converters, offering simplified gate drive circuitry and improved suitability for high-power-density applications. [ABSTRACT FROM AUTHOR]

This article proposes an isolated high‐efficiency resonant LED driver with wide‐input voltage range. The proposed converter is developed by integrating LCC resonant converter and buck‐boost converter. In this topology, the LCC network provides many features including the integration of buck‐boost filter inductor and the transformer magnetizing inductance. In addition, the LCC network provides zero voltage switching (ZVS) operation of the main switches and zero current switching (ZCS) operation of the rectifier diodes over a wide variation of duty cycle operation. Also, load‐independent output current characteristic with improved efficiency is obtained at the resonant frequency operation which is well‐suited for LED applications. Other topology variations of the proposed converter generating step‐up and step‐down voltage gains are introduced for applications with different input voltage ranges. To validate the theoretical analysis and LED driver operation, a 50 W laboratory prototype of the proposed LED driver is implemented for the wide input voltage of 18–40 V to deliver 500 mA output current to a string of 1–30 LEDs, which corresponds to an output voltage range of 3.3–100 V. [ABSTRACT FROM AUTHOR]

The transportation sector's shift from internal combustion engines to electric vehicles (EVs) has made enough charging facilities necessary. The converter's architecture has undergone several changes to provide the best possible charging for electric vehicles. For EV charging applications, both isolated and non‐isolated converters are employed. The significant strain on switches and losses in the various converter topologies are among the main problems. To minimize these issues, the current‐fed non‐isolated DC–DC converter is proposed with fewer switching devices. The proposed converter design is validated for the EV charging application in the MATLAB/Simulink tool. Moreover, Coati optimized fractional order proportional integral derivative controller is proposed, which provides optimum switching signals for the converter based on the voltage input. Furthermore, the responses are realized for buck and boost modes of operations. It is verified that zero current switching and zero voltage switching are achieved under boost mode. The results analysis demonstrates that the proposed converter has a higher efficiency of 99.7% and 99.02% in buck and boost mode, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT This article introduces a high step‐up isolated multi‐input converter (HSIMIC), which utilizes a three‐winding coupled inductor and a quasi‐Z‐source to obtain an extra‐high voltage gain and to feature galvanic isolation. The HSIMIC only requires a minimum count of active switches. In HSIMIC, diodes have zero current switching (ZCS) features at turn‐off, and leakage energy can be recycled. Based on the configuration of HSIMIC, the input sources can be processed simultaneously or individually. Even if either of the input sources is interrupted, the converter can still function and maintain the high step‐up characteristic. In addition, the input port number can be easily extended to deal with more clean energy sources. The converter operation principle, theoretical analysis, essential parameter design, and simulations are carried out. A 400‐W prototype is built and then tested to verify the theoretical analysis and validate the proposed HSIMIC. [ABSTRACT FROM AUTHOR]

This paper presents a quasi-resonant, isolated, high-gain, Y-source, DC/DC converter for a DC microgrid. Here, quasi-resonance is obtained by the LC tank during the shoot through period, resulting in natural commutation at the turn-off instant of the MOSFETs. The LC tank is formed by an additional parallel capacitor $({C_p})$ (C p) and transformer leakage inductance. The high voltage gain is obtained by including an isolation transformer with lower turns ratio, coupled inductor and voltage doubler. Here, frequency is modulated to regulate the output voltage with ON period $({T_{on}})$ (T on ) constant. This converter's zero current switching feature allows it to operate at a higher switching frequency and thus enhances the power density and efficiency. This converter's continuous input current feature is an added advantage. The proposed converter inherits all the benefits of traditional impedance source converters. Finally, a 250 W hardware prototype is developed, and its performance is tested in the laboratory. [ABSTRACT FROM AUTHOR]

The control of IGBT (insulated gate bipolar transistor) and MOSFET (metal oxide semiconductor field effect transistor) is of great interest nowadays as they are widely used in electric vehicles, photovoltaic applications, and a multitude of systems. The field of power electronics and their correct activation ensures that the transistors are operated without being destroyed. In this work, a double resonant transformer was built and used to produce very high currents. These currents are switched by a full bridge of resonant IGBT transistors to demonstrate the feasibility of exceeding the maximum permissible transistor currents in a resonant system. The system is controlled by the feedback from two current sensors. In this case the currents exceed in a 170% the peak current of the transistor without problems. In this way, resonant circuits with IGBT transistors can be designed with currents lower than the maximum currents of the resonant circuit, therefore reducing the cost of the circuit and reducing the switching losses to nearly zero. [ABSTRACT FROM AUTHOR]

This paper presents a new capacitor charger for energy-harnessing applications such as energy transfer from a low-power battery to a load capacitor. The proposed structure uses a switching technique for step-by-step charging of the load capacitor. It comprises a control section, output stage metal-oxide-semiconductor field-effect transistors, and an external inductor. In order to improve the circuit efficiency under different power transfer scenarios, the switching capacitor charger operates at the boundary of continuous conduction mode and discontinuous conduction mode. Two blocks of peak current controller and zero current detector have been employed in a feedback loop to control the inductor current, which resulted in conduction power dissipation reduction. Also, the circuit with switching at low frequencies significantly reduces the switching loss. The performance of the proposed circuit is demonstrated using theoretical elaborations. In addition, the proposed structure is evaluated and simulated in a 0.18 μ m standard complementary metal-oxide semiconductor technology. Based on the obtained results, the efficiency of the presented circuit at 15.62 mW input power is 96%, and the charging time is about 0.54 ms, which is suitable for low-power applications. [ABSTRACT FROM AUTHOR]

This work offers a fuel cell power system with the ability to distribute power to the load from the electrical source and charge an auxiliary battery utilizing regenerative power flows created by the load. The approach is established on a bidirectional closed‐loop DC converter. A bidirectional DC–DC converter is presented as a means of achieving extremely high voltage energy storage systems (ESSs) for a DC bus or supply of electricity in power applications. This paper presents a novel dual‐active‐bridge (DAB) bidirectional DC–DC converter power management system for hybrid electric vehicles (HEVs). The proposed system makes it possible to charge an additional battery with regenerative power flows and distributes power from the electrical source to the load efficiently. The two main stages of the DAB converter, which are the focus of this work, are an interleaved buck/boost converter on the battery and a three‐phase wye‐wye series resonating converter on the DC bus. Each switch's current stress is greatly reduced by this design, which lowers transmission losses and enhances thermal performance. The interleaved buck conversion on the battery allows for lesser current stress in each switch, resulting in lower transmission loss. The increasing complexity and power of automotive embedded electronic systems have made the use of more potent power electronic converters in automobiles necessary. In recent years, many dual volt (42 V/14 V) bidirectional inverter topologies for automotive systems have been presented. However, the majority of them are either inefficient or use a huge number of transistors and magnetic devices in both parallel and series arrangements. As a result, in this study, a bidirectional high‐efficiency inverter with fewer components is provided. The design, modes of operation, and performance metrics of the DAB converter are examined, emphasizing its ability to achieve zero‐voltage switching (ZVS) and zero current switching (ZCS) throughout its operating range. The suggested system seeks to maximize EV power management, guaranteeing high dependability and efficiency. To test all of the aforementioned qualities, an evaluation version was created, with an average efficiency of 97.5%. This research could have a substantial impact on the advancement of power electronic converters for automotive applications, leading to better EV power management, increased system reliability, and increased overall efficiency. [ABSTRACT FROM AUTHOR]

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Electric vehicles (EVs) have emerged as the best alternative to conventional fossil fuel-based vehicles due to their lower emission rate and operating cost. The escalating growth of EVs has increased the necessity for distributed charging stations. On the other hand, the fast charging of EVs can be improved by the use of efficient converters. Hence, the fractional order proportional resonant (FOPR) controller-based current-fed bidirectional DC-DC converter is proposed in this work for EV charging applications. The output capacitance of the switches is utilized to achieve the resonance condition for zero voltage switching (ZVS) and zero current switching (ZCS). The proposed converter topology is implemented using the MATLAB Simulink tool. The result analysis verified that the proposed converter topology provides better switching characteristics for different operating modes, which is necessary for a high-voltage EV charger. Hence, it is proved that the proposed converter is more efficient for battery charging in EVs. [ABSTRACT FROM AUTHOR]

Abstract A soft switching non‐isolated bidirectional DC–DC converter with an improved voltage conversion ratio without any additional auxiliary switch is presented in this paper. In the proposed converter, improved step‐up/step‐down gain conversion is achieved by employing the coupled inductors method. Also, the auxiliary circuit provides soft switching conditions for all the semiconductor elements, regardless of the power flow direction and without any extra voltage stress. The other switch helps provide soft switching conditions for the main switch. Moreover, the switch used for providing soft switching conditions operates as a synchronous rectifier as well. The additional circuit added to attain soft switching is composed of an inductor, coupled with the converter's main inductor, and two auxiliary diodes. The auxiliary diodes benefit from zero‐current‐switching conditions. Fully soft switching conditions for all semiconductor devices, removing the reverse recovery problem, and a low number of components have led to mitigating switching losses and improving efficiency. Detailed operating principles and a theoretical analysis of the proposed converter are presented. Also, the experimental results of a 220 W prototype circuit are provided to confirm the validity of the proposed topology.

This paper proposes a gallium nitride (GaN)-based very-high-frequency (VHF) resonant flyback converter with integrated magnetics, which utilizes the parasitic inductance and capacitance to reduce the passive components count and volume of the converter. Both the primary leakage inductance and the secondary leakage inductance of the transformer are utilized as the resonance inductor, while the parasitic capacitance of the power devices is utilized as the resonance capacitor. An analytical circuit model is proposed to determine the electrical parameters of the transformer so as to achieve zero voltage switching (ZVS) and zero current switching (ZCS). Furthermore, an air-core transformer was designed using the improved Wheeler's formula, and finite element analyses were carried out to fine-tune the structure to achieve the accurate design of the electrical parameters. Finally, a 30 MHz, 15 W VHF resonant flyback converter prototype is built with an efficiency of 83.1% for the rated power. [ABSTRACT FROM AUTHOR]

A soft switching non‐isolated bidirectional DC–DC converter with an improved voltage conversion ratio without any additional auxiliary switch is presented in this paper. In the proposed converter, improved step‐up/step‐down gain conversion is achieved by employing the coupled inductors method. Also, the auxiliary circuit provides soft switching conditions for all the semiconductor elements, regardless of the power flow direction and without any extra voltage stress. The other switch helps provide soft switching conditions for the main switch. Moreover, the switch used for providing soft switching conditions operates as a synchronous rectifier as well. The additional circuit added to attain soft switching is composed of an inductor, coupled with the converter's main inductor, and two auxiliary diodes. The auxiliary diodes benefit from zero‐current‐switching conditions. Fully soft switching conditions for all semiconductor devices, removing the reverse recovery problem, and a low number of components have led to mitigating switching losses and improving efficiency. Detailed operating principles and a theoretical analysis of the proposed converter are presented. Also, the experimental results of a 220 W prototype circuit are provided to confirm the validity of the proposed topology. [ABSTRACT FROM AUTHOR]

This paper presents a non‐isolated DC‐DC converter designed to validate ultra‐high voltage gain using a modified double boost mode. The objective is to achieve exceptionally high voltage gain by integrating a modified triple boost technique (MTBT), interleaved with second main and auxiliary third MOSFETs, and a modified switched inductor‐capacitor (MSLC), effectively doubling the voltage transfer gain. Furthermore, MSLC is combined with the auxiliary third and double main MOSFET to double the voltage gain while concurrently mitigating voltage stress on the auxiliary MOSFET and diodes in the proposed converter (the PC). Additionally, all diodes in the MTBT operate under zero current switching (ZCS) and the double main and auxiliary third MOSFET face very low current stress at ultra‐high voltage gain. The input current of the PC remains steady without pulsating at a low duty ratio, making the PC more suitable for renewable energy systems. The PC offers numerous advantages, exhibiting high efficiency and ensuring minimal voltage stress on power devices with low current stress on the power switches. Notably, PC aims to elevate input voltages from 30 V to a variable output range of 335 to 600 V, delivering 440 watts at 96.1% efficiency. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a zero‐input‐current‐ripple (ZICR) high‐voltage‐gain dc‐dc converter with an integrated Y‐source network. It achieves zero input current ripple by introducing a parallel branch of an extra inductor, a coupled winding, and a capacitor at the input port. The voltage of the added inductor is opposite to that of the coupled winding. By adding the Y‐source coupled inductor, the boost capability of the converter is improved. The unique boost circuit structure makes that one winding in the three‐winding coupling inductance is step‐down type (the turns ratio n2 < 1) while the other winding is step‐up type (the turns ratio n1 > 1). In such a case, high voltage gain can be obtained under a lower turn ratio of the coupled inductor. The inherent passive clamping circuit clamps the spike voltage noises of the main switch to a low level and improves the efficiency. All the diodes have achieved ZCS (zero current switching) turn‐off. By comparing with several new converters, the advantages of this converter are proved. Finally, a 200‐W, 48‐ to 380‐V, 50‐kHz experimental prototype is built based on the theoretical research. At the rated power, the measured efficiencies with and without ZICR are 95.2% and 95.6%, respectively. [ABSTRACT FROM AUTHOR]

This paper discusses the design and analysis of a three-level LLC (TL-LLC) resonant converter for an electric vehicle (EV) charging application. The proposed two-stage onboard charger comprises an ac-to-dc power factor correction (PFC) stage, followed by the second stage required to provide galvanic isolation and dc-to-dc conversion. The PFC stage uses a bridgeless SEPIC converter with average current control and voltage mode control algorithm for achieving unity power factor (pf) operation with constant DC link voltage. In contrast, the dc/dc stage uses a three-level LLC resonant converter with a frequency control algorithm to control the output voltage. A 1 kW, 360 V output model of the proposed onboard charger is implemented and simulated in PSIM, and the obtained results are investigated and examined in detail. Results obtained from the simulation show a power factor greater than 0.99 with THD less than 5 $$\% $$ % at the input side. For TL-LLC, both zero voltage switching (ZVS) for primary MOSFETs and zero current switching (ZCS) for secondary side rectifier diodes are achieved. [ABSTRACT FROM AUTHOR]

This paper proposes a new soft‐switching bidirectional multiport DC/DC converter for PV/EV applications. The proposed topology is capable of using several different sources simultaneously. Also, it has some benefits including high voltage gain, bidirectional, soft‐switching technique, and multi‐input multi‐output (MIMO) topology. In addition, all inputs of the proposed converter are separate from each other and it causes control of the outputs to be simple in the wake of the common ground of the inputs and outputs. The proposed converter can work on zero current switching (ZCS) conditions on some power semiconductors (power diode/switch) and decreases the switching and conduction losses. It also makes use of semiconductors with lower resistance on‐state (Rds‐on). Using coupled inductor techniques and working of semiconductors under ZCS conditions eliminates the total loss affected by reverse recovery of the power diodes, and a passive clamp circuit can recover the leakage energy released by the leakage inductance of the used coupled inductor. The proposed topology is built and tested in the laboratory. To confirm the accurate operation of the proposed topology, it is tested by Typhoon HIL‐404 emulator at 12 V–12 V–12 V inputs/270 W with 50 kHz switching frequency. [ABSTRACT FROM AUTHOR]

Summary: This paper targets to minimize the peak common mode voltage (CMV) in ultra sparse matrix converters (USMC) by applying new zero vectors for the space vector modulation technique (SVM). Conventional zero vectors in the SVM raise the peak CMV by 42.23%. An increased magnitude of CMV is associated with the occurrence of leakage current, hence resulting in insulation degradation. So, the reduction of peak CMV is necessary for USMC. The proposed method offers suitable switching arrangements using auxiliary shoot through (AST) switches to minimize the peak‐to‐peak CMV. This proposed method holds the advantages of the conventional method, like a wide range of modulation index and zero current switching at the rectifier side, and also reduces the CMV problem. This paper also provides a comparative analysis of the existing reported methods and the proposed method. The effectiveness of the proposed method is validated through both simulation and experimental results. [ABSTRACT FROM AUTHOR]

This article proposes a new interleaved buck converter with a high step-down conversion ratio and soft-switching. The soft-switching conditions for the main IGBTs are achieved with the aid of a simple auxiliary circuit, which comprises a resonant inductor, a resonant capacitor, and a diode. A new interleaved buck converter is realized by adopting two auxiliary circuits separately connected to each one of the legs to provide zero voltage switching (ZVS) and zero current switching (ZCS) turn-on operation. The major advantages of this converter are reduced switching losses, a high step-down ratio, reduced voltage stresses, and no limitation on duty ratio. To validate the theoretical analysis, a laboratory prototype of a 200 V-60 V converter system has been developed and achieved an efficiency of 96% at 250 W output power. [ABSTRACT FROM AUTHOR]

This study presents a novel soft-switching inverter distinguished by a simplified topology and an innovative modulation approach. The design aims to optimize the energy conversion processes commonly found in auxiliary snubber circuits. By minimizing the number of auxiliary switches, the control method is streamlined, thereby enhancing system reliability and cost-efficiency. The principles of operation and conditions for soft-switching are thoroughly analyzed using equivalent circuit models. A 3 kW/16 kHz inverter prototype was constructed, and the experimental results confirm the effectiveness and benefits of the proposed inverter. [ABSTRACT FROM AUTHOR]

Three-level DC–DC converters (TLDCs) have attracted industrial and academic attention because of low main switching voltage ratings, simple clamping structure, and good soft-switching characteristics. This paper proposes a new TLDC with combined operation modes, which can operate in both zero-voltage switching (ZVS) and zero-voltage zero-current switching (ZVZCS) modes. The proposes converter varies soft switching mode with a simple switching combination of Sr1 and Sr2, and follows the best efficiency curves over a wide load range. Compared to conventional ZVS or ZVZCS TLDCs, this solution minimizes the circulating current and increases the overall efficiency. In addition, the current stress of the flying capacitor is also low. And, all these good features are realized by two low VA rating MOSFETs. This paper discusses the circuit, operating principles, and some steady-state characteristics. Finally, experimental data from a 1 kW prototype demonstrates the validity and characteristics of the proposed converter. [ABSTRACT FROM AUTHOR]

A zero current transition (ZCT) pulse-width modulation (PWM) DC–DC boost converter operating in boundary conduction mode (BCM) is proposed in this paper. The auxiliary circuit of the proposed converter ensures the main switch to turn off with ZCT. Also, due to the operation of the proposed converter in BCM, naturally zero current switching (ZCS) is achieved for the turning on process of the main switch and the turning off process of the main diode. The proposed converter does not contain additional voltage and current stresses across the main components. The operation modes and theoretical analysis of the proposed ZCT PWM DC–DC boost converter operating in BCM are shown in detail. Detailed ZCT cell analysis and selection procedure of the resonant components which ensure the ZCT operation of the main switch are realized. The proposed converter is designed and tested, and experimental results are obtained in the laboratory. The total losses of the proposed converter are decreased by 53.77%, and its efficiency is increased by 3.2% compared to hard switching (HS) converter at 462 W nominal output power. [ABSTRACT FROM AUTHOR]

Human observation of the ocean has gradually evolved from the sea surface to systematic monitoring and sampling through seafloor observation networks, and constant current power supply has become the main power supply method for seafloor observation networks due to its high reliability. There are some studies on current source to voltage source converters, but there are few studies on current source to current source (CS/CS) converters, which affects the expansion of power supply networks for seafloor observation networks. In this paper, by employing input current sharing and output voltage doubling circuits, an active clamp dual-inductor isolated CS/CS converter which uses a single-stage conversion circuit to realize constant current source conversion with a wide output voltage range is proposed. Active clamp technology at the primary side of the proposed circuit is employed to recover energy stored in leakage inductance, suppress voltage spikes of the primary side switches, and achieve zero-voltage switching of the primary side switches. The secondary side's output voltage doubling circuit resonates with transformer leakage inductance to achieve zero-current switching of the secondary side diodes, which can reduce losses and enhance efficiency. The operating principles of the proposed circuit are analyzed in detail, and the characteristic and parameter design analysis, including current conversion ratio, transformer turn ratio, power inductors, and resonant capacitors and inductor, are presented. Finally, the experimental results based on a 100 W experimental prototype validate the feasibility of the proposed converter. [ABSTRACT FROM AUTHOR]

The challenge regarding the output voltage regulation control of quasi-resonant converters while concurrently fulfilling zero-current switching is addressed in this study. In particular, an alternative to the usual practice of considering fixed duty cycle operation is presented to deal with the narrow robustness margin against load variations exhibited by this condition. The main contribution was the introduction of an additional block in the control loop that implements a new linear relationship between the duty cycle and the switching frequency in terms of the load current. This block proportionally modifies the duty cycle with the switching frequency that, as usual, is used to regulate the output voltage. The structure of the contribution was obtained by exploiting the knowledge of the differential equations that describe the dynamical behavior of the topology. Although it was shown that this modification could be used regardless of the control scheme implemented for the operation of the converter, its usefulness was illustrated by presenting a modified implementation of a classical P I control scheme. It was shown via numerical evaluations that the robustness of the converter under classical P I control was drastically improved for both increases and decreases in the load value. From the implementation perspective, this contribution is attractive since it exhibits a simple structure and neither requires the use of auxiliary switches nor increases the cost of current solutions. [ABSTRACT FROM AUTHOR]

A novel ac/dc LED driver with power factor correction and soft-switching functions is proposed. The circuit topology mainly consists of two modified single-ended primary inductance converters (SEPIC) with interleaved operation. The first half stage of SEPIC operates like a boost converter and the second half stage operates like a buck–boost converter. Each boost converter is designed to operate in discontinuous current mode (DCM) to function as a power factor corrector (PFC). The two buck–boost converters that share a commonly coupled inductor are designed to operate at near boundary conduction mode (BCM). Without using any active clamping circuit, auxiliary switch or snubber circuit, the active switches can achieve zero-voltage switching on, and all diodes achieve zero-current switching off. First, operation modes in steady state are analyzed, and the mathematical equations for design component parameters are derived. Finally, a prototype circuit of 180 W rated power was built and tested. Experimental results show satisfactory performance of the proposed circuit. [ABSTRACT FROM AUTHOR]

The paper explores the investigation of an inverse Class‐E amplifier featuring a series output filter across various switch‐off duty ratios D. Analysis of different duty ratios as a design parameter reveals their impact on peak switch voltage, output power capability, and maximum operating frequency. Notably, it is demonstrated that adjusting the D ratio affects these parameters, with specific emphasis on achieving a maximum normalized switch voltage lower than 2 and an output power capability exceeding 0.1 for D = 0.7. Furthermore, the paper considers both parasitic shunt capacitance and series inductor in the load network, a departure from previous works that solely focused on the series inductor. The proposed circuit is highlighted for its ease of implementation compared with conventional reactance compensation circuits employing parallel resonant circuits, which are challenging to form directly. An innovative approach is introduced to showcase the broadband performance of the inverse Class‐E amplifier. The measured drain efficiency and output power versus input power at 430 MHz are 82% and 45.3 dBm, respectively. A similar performance can be achieved within the frequency range of 380–600 MHz by proper tuning at saturated power. The measurement results demonstrate a maximum high power‐added efficiency (PAE) of 79% and drain efficiency of 82% within this frequency range, accompanied by a gain exceeding 12.0 dB and output power surpassing 44 dBm. [ABSTRACT FROM AUTHOR]

This paper introduces a resonant switched capacitor converter (RSCC) topology that enhances the operational efficiency by utilizing devices with reduced ratings. The RSCC eliminates bulky magnetic elements, yielding increased power density, modular structure, and compact size compared with switched inductor topologies. Significantly, all the switched capacitors in the proposed converter and approximately 50% of the switching power devices are explicitly rated for the input voltage enabling its use for high‐power applications. A compact inductor is utilized for resonant operation, and the switching frequency of the converter is significantly reduced leading to reduced switching losses and improved efficiency. Zero current turn‐ON and turn‐OFF of the switching devices is achieved. Elimination of load‐side bulky capacitor using inherent output voltage ripple reduction is achieved by aligning the switching phases of the converter such that individual capacitor voltage ripple gets cancelled out. The work extensively covers the analysis of the converter in steady‐state and the effect of non‐idealities during the resonant operation. Further, a detailed design of the topology with a discussion on component selection is presented. The operation of the proposed converter is systematically analyzed through a series of simulation results generated, and the converter is further validated by developing an experimental prototype at a power of 200 W with an efficiency of 95.83%. [ABSTRACT FROM AUTHOR]

Summary: This study designed and evaluated an integrated cascaded pair of full‐bridge LLC resonant bidirectional DC–DC converters usable in varied applications, including in energy storage systems, to function as an interface between two dc voltage buses in a variety of applications. The proposed converter combines an isolated five‐level cascaded H‐bridge LLC (IFCHB‐LLC) resonant circuit with a buck/boost circuit (bidirectional converter BID). In this converter, the inbuilt capabilities of an LLC converter, which function as a current source and a voltage source, were exploited, resulting in the constant current (CC) and constant voltage (CV) charges while CV was implemented in the discharge stage (reverse flow). The modelling of the LLC converter was done following the first harmonic approximation (FHA) approach. Furthermore, to ensure improved efficiency of the proposed system, the passive elements of the resonance tank and isolation transformer ratio were programmed in a manner that the converter can be operated within the zero‐voltage switching (ZVS) and zero‐current switching (ZCS) regions. The feasibility and validity of the converter were tested using a 500 W prototype converter with an input voltage of 200 V resulting in the highest efficiency level of 94.46%. [ABSTRACT FROM AUTHOR]

In this paper, a new active snubber cell for DC‐DC boost converters is introduced for the purpose of soft switching. The introduced snubber cell ensures lossless turning‐on by zero‐voltage transition (ZVT) and turning‐off by zero‐voltage switching (ZVS) of the main switch. Besides, it enables turning‐on by ZVS and turning‐off by zero current switching (ZCS) of the main diode. None of the semiconductor power devices are subjected to extra voltage stress, and all of them operate by soft switching (SS). The converter can successfully maintain the SS even under light loads. Furthermore, the proposed converter structure is advantageous in terms of simplicity and low cost. The operating modes and theoretical analysis of the introduced converter are presented and it is validated using a prototype with a 500 W output power and at the 100 kHz switching frequency. Owing to the proposed active snubber cell, the converter efficiency is achieved as 97.2%. [ABSTRACT FROM AUTHOR]

The object of research is the power part of the two-stage converter. The paper evaluates the parameters of the power part of the two-stage converter with transformer isolation, designed for the transfer of solar battery energy to the 400 V constant voltage network with the possibility of maintaining the maximum power point tracker (MPPT). The primary stage of the converter is made as a push-pull current source inverter topology with an additional switch, which is installed between the common point of the transformer’s primary half-windings and the common point of the primary stage switches. The primary stage switches are made as a series connection of MOSFET transistors and Schottky diodes. The secondary stage has the traditional topology of a half-bridge voltage source inverter on MOSFET. A special switching algorithm of separated commutation is described, which provides non-dissipative snubber turn-on for of the current source inverter switches and their natural zero current turn-off switching (ZCS). The role of a snubber is performed by the leakage inductance of the transformer. For voltage source inverter switches, natural zero voltage switching (Zero Voltage Switching, ZVS) is provided. The role of non-dissipative capacitive switching snubbers may be performed by the MOSFET own output capacitance. The essence of this algorithm is to create a delay between the moment of forced switching on of the main key of the primary link and the moment of forced switching off of the transistor of the secondary link. There is also a small interval of energy return to the input source. Adjustment of the converter for the implementation of MPRT can be carried out by adjusting the ratio of the durations of the conduction state of the main and additional switches of the primary stage relative to the duration of the half-period of the frequency conversion. The types of switches were selected, static losses were estimated, simulation modeling was carried out in the MATLAB/Simulink environment, which confirmed the theoretical conclusions and the presence of soft switching modes. [ABSTRACT FROM AUTHOR]

As research into data centers progresses, the importance of resonant switched-capacitor converters in power supply design becomes more evident. Practical applications reveal that the values of resonant capacitors and inductors may deviate from their nominal values due to various factors, leading to resonant frequency instability. This instability poses a challenge to power electronics technology, affecting system reliability and performance. This paper analyzes the effect of frequency deviation on system functionality, identifies the relationship between output voltage and switching frequency, and proposes a self-tracking frequency strategy to address this issue. Through experimental validation, this approach shows that it maintains synchronization between switching and resonant frequencies, reducing losses associated with frequency misalignment. Simulation and experimental results validate the converter's stable operation and its ability to achieve zero-voltage and zero-current switching. [ABSTRACT FROM AUTHOR]

This paper accentuates the study of LLC resonant converter by a comparative analysis of the properties of LLC resonant and pulse width modulation direct current-direct current converters. Lately, LLC resonant converters have become more appealing and desirable in many applications than other pulse width modulation converters (e.g., Buck, Boost, Cuk) for their soft-switching techniques like zero voltage switching, zero current switching as well as low electromagnetic interference. This paper presents an analysis of efficiency variation, output voltage's ripple, and various transient performances like percentage overshoot, and the settling time with the variation of load current in a comparative way between LLC resonant converter's buck, boost operation, and conventional pulse width modulation converter's buck, boost operation. Feedback prop ortio nal-i ntegr al-d eriva tive duty cycle controller is used in all converter topologies for some specific analysis. A fixed input voltage of 100 V is selected for simulation and an output voltage of 24 V for buck operation and 120 V for boost operation are chosen. For simulation purposes, MATLAB/SIMULINK software is used. [ABSTRACT FROM AUTHOR]

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%.

A novel any cell to any cell equalization circuit topology with small column, low weight, low cost, and high efficiency is proposed for serial-connected batteries, especially suitable for unmanned aerial vehicles, satellites, and other fields with strict requirements on size, weight, reliability, and safety. To solve the problems of high switching losses in equalization circuits and low reliability of complex control schemes. A half-bridge circuit to convert the DC voltage of the battery into AC voltage is employed, and the energy is exchanged autonomously via the bus. At the same time, LC resonant circuit is used to achieve zero-current switching of the MOSFET, thus reduces greatly the switching losses. The working principle is analyzed by theoretical derivation, and the parameters of the circuit are optimized through circuit simulation. Furthermore, experiments which support six cells equalization are carried out to verify the feasibility and advantage of this topology. This equalization uses a bus-type architecture to improve equalization efficiency and topological flexibility making it even more valuable in the industrial and aerospace fields. [ABSTRACT FROM AUTHOR]

In this paper, a single-stage step-down power factor corrector without a full-bridge rectifier is developed, which is designed to operate in discontinuous conduction mode (DCM). In terms of control, the DCM has the advantages of simple control and easy realization, no slope compensation, zero current switching, and no diode reverse current. By sampling the output voltage and using the voltage-follower control to generate the necessary control force to drive the power switch, not only can the output voltage be stabilized at the desired value, but also the input current can be, as much as possible, in the form of a sinusoidal waveform and can follow the phase of the input voltage. Moreover, the harmonic distortion meets the requirements of the IEC6100-3-2 Class D harmonics standard, and, thus, the proposed rectifier is appropriate for the computer, computer monitor, and television receiver. Eventually, by means of mathematical deductions, simulations by PSIM version 9.1, and experimental results, the feasibility and effectiveness of the proposed circuit can be verified. [ABSTRACT FROM AUTHOR]

This letter presents a multifunctionality reconfigurable substrate-integrated waveguide (SIW) filter embedded in a microstrip line. The proposed filter used an electromagnetic bandgap structure (EBG) to compact the size and improve the electromagnetic features. The SIW filter consists of a three-cell EBG with metallic circular-shaped connected to the ground through cylindrical vias. Firstly, the base SIW structure offers a wide passband filtering response, and then, to obtain selective passband, wide band rejection, and controllable resonance frequencies, a three-cell EBG along with four diodes has been attached. The filter is designed and printed on a Rogers 4003 substrate with a thickness of 1 mm and is experimentally validated for functionalities operated at three modes with an average 3 dB bandwidth of 115 MHz in each frequency. In addition to that, two transmission zeros (TZ) have been produced in the upper band frequency. The filter's response is also tunable by turning the diode off or on and changing the main parameters of EBG, the gab, and the position between cells. The study explores resonance frequency alterations in a three-state system of on/off. By eliminating or diminishing specific modes, and incorporating diodes, distinct resonance behaviors are observed. Moreover, shifting frequency resonance in a multiparameter system has been investigated. Increasing B1 induces a significant shift to lower values, while an increase in D1 leads to a decrease in the first and second resonance frequencies and an upward shift in the third. The designed filter has been fabricated and tested to compare and confirm simulated responses. Simulation and measurement results are in good agreement. The S-parameters of measured results gained a good response (>15 dB) within the passbands and stopbands and an insertion loss of 1.5 dB suitable for 5G and Wi-Fi systems. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to regarding the application of traditional pulse frequency modulation control full-bridge LLC resonant converters in wide output voltage fields such as on-board chargers, there are issues with wide frequency adjustment ranges and low conversion efficiency. Design/methodology/approach: To address these issues, this paper proposes a fixed-frequency pulse width modulation (PWM) control strategy for a full-bridge LLC resonant converter, which adjusts the gain by adjusting the duty cycle of the switches. In the full-bridge LLC converter, the two switches of the lower bridge arm are controlled by a fixed-frequency and fixed duty cycle, with their switching frequency equal to the resonant frequency, whereas the two switches of the upper bridge arm are controlled by a fixed-frequency PWM to adjust the output voltage. The operation modes of the converter are analyzed in detail, and a mathematical model of the converter is established. The gain characteristics of the converter under the fixed-frequency PWM control strategy are deeply analyzed, and the conditions for implementing zero-voltage switching (ZVS) soft switching in the converter are also analyzed in detail. The use of fixed-frequency PWM control simplifies the design of resonant parameters, and the fixed-frequency control is conducive to the design of magnetic components. Findings: According to the fixed-frequency PWM control strategy proposed in this paper, the correctness of the control strategy is verified through simulation and the development and testing of a 500-W experimental prototype. Test results show that the primary side switches of the converter achieve ZVS and the secondary side rectifier diodes achieve zero-current switching, effectively reducing the switching losses of the converter. In addition, the control strategy reduces the reactive circulating current of the converter, and the peak efficiency of the experimental prototype can reach 95.2%. Originality/value: The feasibility of the fixed-frequency PWM control strategy was verified through experiments, which has significant implications for improving the efficiency of the converter and simplifying the design of resonant parameters and magnetic components in wide output voltage fields such as on-board chargers. [ABSTRACT FROM AUTHOR]

In energy storage systems, multiple energy storage monomers are usually connected in series to obtain higher voltages, but the inconsistency of the voltage of each energy storage monomer will reduce the utilization of the storage unit. To address this problem, this article proposes a method for equalizing the voltage of series energy storage units based on LC resonant circuit. The equalization circuit consists of a switch array and an LC resonant converter, which can achieve energy transfer between any monomer and continuous multi‐monomer, and realize zero‐current conduction of the switch. The equalization circuit does not have a large number of magnetic components, and for each additional energy storage monomer, the circuit only needs to add a pair of switches, which has the advantages of high flexibility and expandability. Finally, the equalization simulation experiments are conducted on the Matlab/Simulink platform for the energy storage unit composed of four series‐connected energy storage monomers. The experimental results show that under static equalization, the voltage reaches equalization in about 25 min and the equalization efficiency reaches 96.64%, which greatly reduces the switching loss, improves the equalization speed and efficiency, and verifies the feasibility and effectiveness of the method. [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]

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]

Modeling time series of multilayer network data is challenging due to the peculiar characteristics of real-world networks, such as sparsity and abrupt structural changes. Moreover, the impact of external factors on the network edges is highly heterogeneous due to edge- and time-specific effects. Capturing all these features results in a very high-dimensional inference problem. A novel tensor-on-tensor regression model is proposed, which integrates zero-inflated logistic regression to deal with the sparsity, and Markov-switching coefficients to account for structural changes. A tensor representation and decomposition of the regression coefficients are used to tackle the high-dimensionality and account for the heterogeneous impact of the covariate tensor across the response variables. The inference is performed following a Bayesian approach, and an efficient Gibbs sampler is developed for posterior approximation. Our methodology applied to financial and email networks detects different connectivity regimes and uncovers the role of covariates in the edge-formation process, which are relevant in risk and resource management. Code is available on GitHub. for this article are available online. [ABSTRACT FROM AUTHOR]

High-gain DC/DC converters play critical roles in most renewable-energy applications such as wind and solar power. A significant number of the high-gain converters are utilized to boost voltage gain by employing an excessive duty cycle and low turn ratio. However, the operation in high duty cycle raises losses and costs, lowers system effectiveness, and results in a low efficiency. This paper proposes a novel solution for a high-gain DC/DC boost converter. The proposed converter can be utilized in low input voltage scenarios that require a large voltage gain, such as solar photovoltaic panels and fuel cells. The novel topology is characterized by a simple operation, high voltage gain, improved efficiency by utilizing two resonance circuits, and continuous input current. An experimental high-gain boost converter with a power output of 300 watts and a voltage ranging from 20 volts to 160 volts is utilized to demonstrate the efficiency of the proposed converter topology.

This study proposes a novel isolated multiport bidirectional DC/DC converter (IMBC) that combines soft-switching (SS) and resistor-capacitor-diode (RCD) snubber circuits for battery charge and discharge applications in photovoltaic (PV) power systems. The proposed SS circuit operates at zero-current (ZC) switching (ZCS) when the switches are on to reduce the switching losses. The RCD snubber circuit also suppresses the overvoltage when turning off switches. Combining the two circuits also enables a more comprehensive operating range for SS, resulting in low losses and high efficiency. A thorough study of operating systems and design considerations is shown. PSIM illustrates the effectiveness of the suggested control method. A prototype of the suggested IMBC with an output voltage of 120 V and an output power of 150 W is constructed to confirm the viability and efficiency of the suggested topology. The maximum efficacy of the suggested topology in the step-up mode for the PV arrays is about 96.4% at an input voltage of 20.5 V and output power of 150 W. In comparison, the efficiency is about 98.5% in the step-down mode for charging and discharging the battery which is considered a highly satisfactory performance.

This paper presents a new soft switching (SS) multiphase interleaved boost converter (MIBC) consisting of three boost converters (BCs) that operate rapidly and efficiently to charge a lithium-ion battery for photovoltaic (PV) power system applications. This suggested converter can operate both active power switches at zero current switching (ZCS), and when switched off, it works at zero voltage switching (ZVS), which reduces switching losses and increases switching efficiency (SF). An interleaving structure is employed to decrease the conduction losses and reduce the input current ripple (ICR) and output voltage ripple (OVR) to increase the power rating. The suggested converter regulates the input and output power by modulating the phase shift in the pulse width modulation (PWM) technique using the maximum power point tracking (MPPT) algorithm via two closed feedback loops, one for a slower external loop and the other for a faster PWM control internal loop, similar to current mode control. The suggested converter has high voltage (HV) gain due to the coupled inductors (CIs), which act as a transformer. This magnetic design structure in both the steady-state and transient states also decreases the size and enhances the converter’s performance. Finally, the suggested converter was experimentally verified on a 285W prototype, and the maximum efficiency was found to be 98%, based on modeling and experimental data.

Abstract A new high step‐up DC–DC converter is proposed in this study. In the proposed converter with voltage lift technique and coupled inductors (CIs) a high voltage gain is achieved. Although the proposed converter has coupled inductors, the input current is continuous and the input current ripple is low. The proposed converter has only one switch and does not have any auxiliary switch, in which the control of the switch is easy. Soft switching condition is presented for the switch in the converter as zero current switching (ZCS) for turning on instant and zero voltage switching (ZVS) for turning off instant, in which the efficiency is increased. For all diodes expect two diodes in the converter ZCS condition is provided when diodes turn off that reverse recovery problem is solved for these diodes. The proposed converter is fully analyzed and described operation of it. To confirm theoretical analysis, 300 W of the proposed converter is implemented and tested, for which in full load an efficiency of 96.5% is achieved.

The increase in demand for high voltage boost features such as solar cells and fuel cells has increased the inefficiency of the traditional boost circuit due to the high duty ratio. In this paper, to supply the output voltage of renewable energy sources and overcome their low voltage, a highly boosted interleaved sepic converter without coupled inductor is proposed. The proposed converter has various advantages, which can be mentioned in reducing the voltage on the converter switch and providing switching conditions at zero current for switches and diodes. Also, the implementation of the control circuit is simple, and the input current ripple of the converter is very low. The analysis and relationships of the converter design are stated, and it is simulated in the PSPICE software. To check the correctness of the design, a sample of the converter has been implemented in the laboratory. The results of the laboratory sample confirm the theoretical analysis of the converter.

The power-electronics converters are increasingly applied in modern power system, which contains various sub-systems, such as renewable energy power plants and high voltage direct current transmission systems, etc. The electromagnetic transient simulation has been one of the important tools for the study of complex system containing large numbers of power converters. The coordination control of the power converters and corresponding power generation and load units is one of the challenges ensuring stability and obtaining optimal efficiency. However, the detailed modeling of the power converters considering the conduction and switching losses can cost a great number of computation resources, which makes it difficult to simulate a large system. This work proposed a current injection method for converter power loss representation, which can accurately consider the conduction and switching losses of the power-electronics switches with low computation complexity. A look-up table (LUT) of the power loss ratio is calculated before the simulation, and a current source representing the power loss is connected in parallel with the converter to track the reference loss generated by the look-up table. The proposed method can be combined with multiple converter modeling schemes, such as the two-resistance model, the switching-function model, and the average value model, etc. The topologies of the two-level converter and the modular multi-level converter (MMC) were used in the case studies to demonstrate the effectiveness of the proposed method. Compared to the device-level model, the simulation power loss deviation is 0.64% and 4.13% applying the current injection method model in the case studies of the two-level converter and the MMC. [ABSTRACT FROM AUTHOR]