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Due to their significant performance, Phase-Shifted Full-Bridge Converters (PSFBCs) have gained widespread adoption in medium- and high-power applications. The performance of a PSFBC is greatly influenced by its magnetic components, namely the transformer and resonance inductor. To address these challenges, this paper proposes a parameter optimization of magnetic components for PSFBCs, specifically the transformer turns ratio and resonance inductor value, to enhance conversion efficiency and minimize operational loss. A digital twin of PSFBCs enabling a more accurate loss estimation is proposed to achieve this objective. The proposed loss estimation method precisely calculates the effective and circulation intervals and the corresponding current points of the primary-side transformer current, resulting in improved accuracy. By leveraging the digital twin, the effects of transformer turns ratio and resonant inductor value on the conversion efficiency of a PSFBC can be efficiently simulated. This facilitates the parameter optimization of magnetic components, thereby minimizing operational losses across different application scenarios. This paper also designs and implements a PSFBC prototype with a rated input voltage of 380 V, output voltage of 24 V, and output current of 20 A. The experimental results show the influences of transformer turns ratio and resonant inductor value on the PSFBC and validate the proposed digital twin. The proposed parameter optimization of magnetic components is further evaluated across two application scenarios with varying utilization rates. The simulation results indicate a reduction of approximately 14% in operational loss per hour after applying the parameter optimization of magnetic components for the PSFBC used as a battery charger. The results demonstrate the effectiveness and practicality of the proposed digital twin in designing PSFBCs. [ABSTRACT FROM AUTHOR]

This study proposed a novel non-isolated half-bridge Inductor-Inductor-Capacitor (HB LLC) resonant converter with automatic resonant frequency adjustment ability and a circulating current suppression auxiliary circuit. The proposed converter employs a hybrid modulation technique based on frequency modulation (FM) and pulse width modulation (PWM) to regulate the output voltage. At the nominal operating point, all the excellent attributes of a conventional LLC converter over the entire load range are maintained and output voltage control is achieved with FM. However, when the input voltage decreased to a level that LLC output voltage cannot be maintained with FM, the primary switches will operate at the minimum switching frequency and the auxiliary switch will be turned ON with PWM. The auxiliary switch is turned ON with zero-voltage switching and automatically matching the circuit resonant frequency with the switching frequency for optimal operation. The effective resonant inductor is energised directly from the dc bus storing more energy which is later released to the load to achieving high gain while maintaining the desired output voltage with a narrow frequency span. In addition, the converter exhibits low circulating current under an enhanced gain condition. Experimental results are presented on a 60 W prototype to validate the theoretical prediction. The proposed converter has a peak efficiency of 97%. [ABSTRACT FROM AUTHOR]

A resonant inductor and two clamping diodes are introduced into the secondary phase shift full-bridge converter (SPS-FBC), which can well suppress voltage spike across the rectifiers. However, the resonant inductor and two clamping diodes will bring some other problems. In this study, an auxiliary winding in series with the resonant inductor is added to the SPS-FBC to reset the clamp diode current rapidly. The auxiliary winding not only reduces the circulation losses of the switches and the clamping diodes, but also makes the clamping diodes naturally turn-off and avoids the reverse recovery even when the output filter inductance and magnetising inductance are relatively large. The principle of operation and performance are illustrated and verified on a 1.5 kW experimental circuit. In addition, the efficiency and losses of the converters with/without reset winding are compared and analysed. The efficiency of the converter with reset winding is significantly improved over the entire operating range and the peak efficiency is 96.60% at full load. [ABSTRACT FROM AUTHOR]

This paper presents a new method of controlling resonant switches of a converter, in which the instants of control pulses supply to the main and auxiliary switches of the circuit are strictly synchronized with pulse-width modulation (PWM) logic signals. Any classical options providing the specified quality of the output voltage and current can be used as such signals. The control pulses durations of the main switches have the same time intervals as those of the PWM control signals, since the control pulses are shifted relative to the PWM signals by a constant time delay. The durations of control pulses of auxiliary switches used to activate resonant switching processes are constant and independent of changes of the electric mode parameters of the circuit and the scatter of the parameters of resonant circuit components. The synchronizing mode is shown to be achieved by introducing two additional time intervals into each resonant switching cycle compensating the effect of external and internal factors on the duration of the required control pulses for the main and auxiliary switches of the converter. Such additional time intervals are the duration of free—that is, without significant loss of power—circulation of current (energy) in the inductance of the resonant circuit. In addition, it is shown that the necessary conditions for free circulation are the capability of the main converter switches for bilateral current conductivity and the absence of energy absorption sources in the circulation circuit. The diagrams are presented of switching processes demonstrating the advantages of a new method for controlling resonant switches of the inverter in a wide range of the supply voltage and load current variations of the circuit. [ABSTRACT FROM AUTHOR]

This study aims to solve a problem that exists with impedance matching networks in terms of extra cost and power loss of electronic components in a four-coil wireless power transfer (WPT) system using class E power amplifier as power supply, which is not conducive to the improvement of system efficiency and output power. A design method of sharing the resonant inductor in class E power amplifier and the excitation coil in the four-coil WPT system is proposed. This method comprehensively considers the output power and transfer efficiency of the system, the number of coil turns, coil size and many other factors. Compared with the traditional four-coil system using a class E power amplifier as a power supply, the proposed method simplified the system structure by leaving out a resonant inductor and load matching circuit, which can reduce the power loss of system and improve efficiency. Moreover, the precisely tuning of resonant inductor was not necessary, which improved the stability of the system. The correctness and feasibility of the parameter design method were verified by experiments. The experimental results showed that the output power of the system was increased by 18.7%, the efficiency was increased by 11%, and the transmission distance was up to 0.7 m, which is suitable for wireless power supply of electronics and sensors.

In this paper, a three-air-gapped structure of a ferrite core for a resonant inductor is proposed. The electromagnetic and thermal field models are built using a 3D finite element method. Compared with the conventional signal-air-gapped structure of a ferrite core, the simulation and analysis results show that the proposed three-air-gapped ferrite core resonant inductor can reduce eddy-current loss and decrease temperature rise. In addition, the optimal position of air-gapped is presented.

Pulsed electric field technology is an emerging nonthermal food processing method. PEF food processing requires a high voltage pulse generator that produces high intensive pulses to be delivered to the food product. Innovation in semiconductor technology motivates researchers to modernize high voltage pulse generators to reduce the cost, size, and complexities in circuit operation and to increase the suitability for food processing since the last few decades. The present study aims to explore a high voltage pulse generator for electroporation study. The implemented high voltage pulse generator develops ∿1.62 kV with adjustable pulse widths of 0.62 μs and 1.2 μs. The pulse frequency can be adjusted to 1, 10, 20, and 51 kHz by using a preprogrammed microcontroller. The implemented pulse generator is simple and compact at affordable cost. Experiments were conducted to prove the feasibility of the implemented high voltage pulse generator to inactivate Escherichia coli microorganisms. Escherichia coli cells were exposed to the electric field intensity produced by the implemented pulse generator and the observed results showed that there is a significant reduction of 5.9 log scale from the initial concentration. [ABSTRACT FROM AUTHOR]

The paper deals with the effectiveness of composite resonant switches in a serial-parallel LCC tank of a voltage-source inverter (VSI). It has been shown that these circuits operate in the duplex mode of resonant switching, in which the main switches in the output circuit of the inverter have zero voltages and currents. The use of composite resonant switches of this type requires voltage control on the capacitor of the serial LC circuit, and there are three ways to solve this problem in a circuit. Therefore, three new variants of VSIs using composite resonant switches have been developed. The integration process of a composite resonant switch in the inverter structure is based on typical variants of VSIs with resonant commutation, which show a maximum efficiency reduction of dynamic energy loss. The effectiveness of the circuit is designed with additional power losses that accrue to the inverter via the auxiliary resonant circuit in mind. Analytical estimation of additional power losses is done by mathematical calculation of the envelope of the resonant inductor current amplitude continuously changing over the period of the inverter output frequency. It has been shown that the maximum efficiency is possessed by a circuit in which the resonant inductor is designed as a reactive component with two magnetically coupled windings. [ABSTRACT FROM AUTHOR]

A design methodology is introduced to select a minimum core volume for an inductor or coupled inductors experiencing appreciable core loss. The geometric constant (Kgac) has been found to be a power function of the core volume for commercial toroidal, ER, and PQ cores, permitting the total loss to be expressed as a direct function of the core volume. The inductor is designed to meet specific loss or thermal constraints. An iterative procedure is described in which 2-D or 3-D proximity effects are first neglected and then subsequently incorporated via finite-element simulation. The methodology is demonstrated for coupled inductors in a 5-MHz converter in critical conduction mode. The core loss is verified using rectangular excitation and the winding loss is inferred from thermal measurements. [ABSTRACT FROM AUTHOR]

This study presents a two‐switch continuous conduction mode pulse width modulation flyback converter that employs an LC snubber circuit. The snubber circuit is used to achieve zero voltage switching (ZVS) operation for the main switches during the turn‐off transition and soft switching for power diodes. With the proposed LC snubber, the magnetic energy in the transformer leakage inductance can be fully recycled and transferred to the input side. The resonant circuit consists of a resonant inductor, a resonant capacitor and two diodes. The operating principles, theoretical analysis and the design methodology of ZVS two‐switch continuous conduction mode (CCM) flyback converter are presented. A 200 W (50 V/4 A) laboratory prototype of the proposed converter, operating at a switching frequency of 300 kHz is built to verify the theoretical analysis. At full load the efficiency is 94%. [ABSTRACT FROM AUTHOR]

This paper presents a new implementation of resonant switching on the dc side in power converters, which can significantly reduce the energy of dynamic losses with a minimal amount of additional elements. These methods are carried out on the basis of the notion of resonant switching by integrating its structure into the input circuit of the converter. Resonant switches of the first and third type switched at zero voltage and resonant switches of the second type switched at zero current are used in the voltage inverters. Dual resonance switch options are used in the current inverters. Basic variants are considered in which the resonant circuit has a direct connection with the input voltage or current source, as well as converter circuits with an additional switch. The active resonant process control is used in all variants, which is synchronized with the PWM control of switch elements of the converter. [ABSTRACT FROM AUTHOR]

The problem of reducing the switching losses for high-power converters is analyzed. A reduction in the dynamic losses helps improve the basic energy characteristics of a converter and reduce its overall dimensions and mass. Three-phase inverter designs in which the switching losses are minimized through the use of resonant switches with an oscillator circuit on the ac side are presented. It is demonstrated that, at high voltages and currents, one should use only those types of resonant switches in which the resonant inductor and the auxiliary switch are removed from the power current circuit of a converter. The practical efficiency of resonant switches of the type under review is evaluated. [ABSTRACT FROM AUTHOR]

The operation of traditional rectifiers such as half-wave and bridge rectifiers in wireless power transfer applications may be inefficient and can reduce the amount of power that is delivered to a load. An alternative is to use Class E resonant rectifiers that are known to operate efficiently at high resonant frequencies and at large input voltages. Class E rectifiers have a near sinusoidal input current which leads to an improved overall system performance and increased efficiency, especially that of the transmitting coil driver. This paper is the first to investigate the use of Class E resonant rectifiers in wireless power transfer systems based on resonant inductive coupling. A piecewise linear state-space representation is used to model the Class E rectifier including the rectifying diode's forward voltage drop, its ON resistance, and the equivalent series resistance of the resonant inductor. Power quality parameters, such as power factor and total harmonic distortion, are calculated for different loading conditions. Extensive experimental results based on a 10-W prototype are presented to confirm the performed analysis and the efficient operation of the rectifier. An impressive operating efficiency of 94.43% has been achieved at a resonant frequency of 800 kHz. [ABSTRACT FROM AUTHOR]

In this paper, the merits of a high-frequency resonant converter for supplying dielectric barrier discharges (DBD) devices are established. It is shown that, thanks to its high-frequency operating condition, such a converter allows to supply DBD devices with short discharge current pulses, a high repetition rate, and to control the injected power. In addition, such a topology eliminates the matter of connecting a high-voltage transformer directly across the DBD device and avoids the issues related to the parasitic capacitances of the latter which disturbs the control the power transfer to the plasma. The design issues of the converter, including the inverter and its switches, the resonant inductor, and the parameter drift compensation are studied. An experimental validation is performed: a mega Hertz resonant converter using GaN FET switches has been manufactured and tested with an excimer lamp. [ABSTRACT FROM AUTHOR]

This paper presents a high-performance resonant gate-drive circuit for MOSFETs and IGBTs, which has high efficiency, fast switching capability, high robustness, and simple topology and control scheme. The proposed gate-drive circuit recycles the gate energy through a resonant inductor. The resonant inductor is precharged before resonance to achieve fast switching. After resonance, the circuit feeds back the remaining energy stored in the inductor. Power loss of the resonant gate-drive circuit is analyzed, and a design procedure to minimize the power loss by optimizing the inductor and precharge time is presented. Experimental results are shown to verify the effectiveness of the proposed circuit. Compared to conventional gate drivers, the proposed circuit reduces the power loss by 80%. [ABSTRACT FROM AUTHOR]

A novel quasi-resonant bridge modular switched-capacitor converter (BMSCC) is proposed in the paper. The main merit is that its resonant circuit has high stability and simplicity, resulting from the employment of the stray inductance distributed in the circuit as a collective resonant inductor. Accordingly, the current spike during switching operation is removed due to zero-current-switching (ZCS) realization. Another distinct merit is that the proposed converter features symmetric construction. With this kind of construction, the voltage ripple of charge/pump capacitors can be cancelled out with each other and then output voltage ripple will be largely reduced. Thus, it is unnecessary to use a bulky capacitor to reduce output voltage ripple. Compared with conventional SCCs, at the same conversion ratio, the BMSCC with symmetric construction requires fewer switches and capacitors with lower voltage stress, so as to cut the size and cost and promote the power destiny further. It is also noteworthy that the symmetric construction character assures that the two symmetric parts can work independently under a simplified control strategy. In addition, the modular configuration contributes to convenient voltage extension conveniently. The simulation and experimental results of a 100 W prototype with a voltage conversion ratio of eight validate the principle and features of this topology. [ABSTRACT FROM AUTHOR]

Basic types of resonant switches with zero voltage and zero current switching are presented. Their main properties and characteristics are considered. Application of all types of resonant switches with the frequency and pulse-width control is shown. [ABSTRACT FROM AUTHOR]

A conventional phase-shift full-bridge (PSFB) converter with two clamp diodes and an additional resonant inductor is widely used for front-end dc/dc stage in the distributed power system. However, the hold-up-time requirement limits its operating duty ratio at normal operation. It results in conduction loss caused by circulating current. Therefore, a wide-range zero-voltage switching (ZVS) PSFB converter with reduced conduction loss caused by circulating current is proposed in this paper. The proposed converter adopts the large resonant inductance and replaces clamp diodes in the conventional PSFB converter with MOSFET switches. With these modifications, the proposed converter can achieve the ZVS operation over wide load range as well as can reduce the conduction loss caused by the circulating current. These advantages result in the improvement of whole load efficiency. The operational principle and analysis of the proposed converter are presented and verified by the 1.2-kW prototype. [ABSTRACT FROM PUBLISHER]

This paper presents a design procedure for inductors based on low-permeability magnetic materials, for use in very high frequency power conversion. The proposed procedure offers an easy and fast way to compare different magnetic materials based on Steinmetz parameters and quickly select the best among them, to estimate the achievable inductor quality factor and size, and to design the inductor. Approximations used in the proposed methods are discussed. Geometry optimization of magnetic-core inductors is also investigated. The proposed design procedure and methods are verified by experiments. [ABSTRACT FROM PUBLISHER]

A soft-switching single-ended primary inductor converter (SEPIC) is presented in this paper. An auxiliary switch and a clamp capacitor are connected. A coupled inductor and an auxiliary inductor are utilized to obtain ripple-free input current and achieve zero-voltage-switching (ZVS) operation of the main and auxiliary switches. The voltage multiplier technique and active clamp technique are applied to the conventional SEPIC converter to increase the voltage gain, reduce the voltage stresses of the power switches and diode. Moreover, by utilizing the resonance between the resonant inductor and the capacitor in the voltage multiplier circuit, the zero-current-switching operation of the output diode is achieved and its reverse-recovery loss is significantly reduced. The proposed converter achieves high efficiency due to soft-switching commutations of the power semiconductor devices. The presented theoretical analysis is verified by a prototype of 100 kHz and 80 W converter. Also, the measured efficiency of the proposed converter has reached a value of 94.8% at the maximum output power. [ABSTRACT FROM AUTHOR]

In this paper, the analysis and design of a three-level LLC series resonant converter (TL LLC SRC) for high- and wide-input-voltage applications is presented. The TL LLC SRC discussed in this paper consists of two half-bridge LLC SRCs in series, sharing a resonant inductor and a transformer. Its main advantages are that the voltage across each switch is clamped at half of the input voltage and that voltage balance is achieved. Thus, it is suitable for high-input-voltage applications. Moreover, due to its simple driving signals, the additional circulating current of the conventional TL LLC SRCs does not appear in the converter, and a simpler driving circuitry is allowed to be designed. With this converter, the operation principles, the gain of the LLC resonant tank, and the zero-voltage-switching condition under wide input voltage variation are analyzed. Both the current and voltage stresses over different design factors of the resonant tank are discussed as well. Based on the results of these analyses, a design example is provided and its validity is confirmed by an experiment involving a prototype converter with an input of 400-600 V and an output of 48 V/20 A. In addition, a family of TL LLC SRCs with double-resonant tanks for high-input-voltage applications is introduced. While this paper deals with a TL LLC SRC, the analysis results can be applied to other TL LLC SRCs for wide-input-voltage applications. [ABSTRACT FROM AUTHOR]

A new transformer integrated with additional resonant inductor is proposed in this paper. By winding on outer side of transformer, the proposed transformer can implement the additional resonant inductor without extra magnetic component. As a result, it can reduce cost and core loss due to the additional resonant inductor. In addition, it can adopt primary clamping diodes to reduce the voltage ringing of secondary rectifiers, although the additional resonant inductor and the transformer are integrated physically. Experimental result of 1200 W (12 V, 100 A) prototype shows that the phase-shift full-bridge converter incorporated with proposed transformer can achieve high efficiency and low cost. [ABSTRACT FROM AUTHOR]

The interleaved operation of a two-inductor boost converter system is a very attractive solution for converting the low input voltage (30-50 V) of distributed power sources, such as photovoltaic and fuel cells, to the high output voltage (380-760 V) required in grid-connected power-conversion applications. However, a soft-switching method is required in the two main switches to increase the overall power conversion efficiency. This paper proposes a zero-voltage-transition (ZVT) two-inductor boost converter using a single resonant inductor to meet these needs. To satisfy the requirement of soft switching in the two main switches, a resonant cell is constructed at the output side with a bidirectional switch, two auxiliary diodes, and a single resonant inductor. This converter has the advantages of simple circuitry, reduced size, and low cost due to a single resonant inductor. The validity of the proposed ZVT two-inductor boost converter is verified through experimental results. [ABSTRACT FROM AUTHOR]

In this paper, a level-shifting voltage-copier circuitry is introduced to convert one or two input voltage levels to eight voltage levels. The voltage copier consists of five kinds of conversion circuits. Each circuit includes only six to seven electronic components, which can ensure the simplicity and reliability of the voltage copier. A resonant inductor is further added to improve the performance of these circuits. A high-efficiency resonant voltage copier is introduced. Simulation and experimental results verify the performance of the voltage copier and the design method. The circuit family provides a useful method for voltage conversion under multiple-input sources to multiple outputs. [ABSTRACT FROM AUTHOR]

This paper investigates the loss characteristics of RF magnetic materials for power conversion applications in the 10 to 100 MHz range. A measurement method is proposed that provides a direct measurement of an inductor quality factor QL as a function of inductor current at RF frequencies, and enables indirect calculation of core loss as a function of flux density. Possible sources of error in measurement and calculation are evaluated and addressed. The proposed method is used to identify loss characteristics of several commercial RF magnetic-core materials. The loss characteristics of these materials, which have not previously been available, are illustrated and compared in tables and figures. The use of the method and data is demonstrated in the design of a magnetic-core inductor, which is applied in a 30-MHz inverter. The results of this paper are thus useful for the design of magnetic components for very high frequency applications. [ABSTRACT FROM AUTHOR]

In this paper, a new zero-current switching pulse width modulation forward converter is introduced using a new switching algorithm for the auxiliary circuit. In the proposed converter, transformer core is reset through a resonance, and thus, reset winding is not required which is the main advantage of this converter over existing zero-current switching forward converters. The simple auxiliary circuit of this converter is just composed of an auxiliary switch and a capacitor that provides zero-current switching for the main switch and also resets the transformer core. Furthermore, the proposed auxiliary circuit uses the leakage inductance of the transformer for the resonant inductor and does not require any additional inductor which is another advantage of the proposed converter over conventional zero-current switching forward converters. Also, the auxiliary switch is soft switched. The proposed converter is analyzed and design procedure of the auxiliary circuit is discussed. The presented experimental results confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

This study aims to solve a problem that exists with impedance matching networks in terms of extra cost and power loss of electronic components in a four-coil wireless power transfer (WPT) system using class E power amplifier as power supply, which is not conducive to the improvement of system efficiency and output power. A design method of sharing the resonant inductor in class E power amplifier and the excitation coil in the four-coil WPT system is proposed. This method comprehensively considers the output power and transfer efficiency of the system, the number of coil turns, coil size and many other factors. Compared with the traditional four-coil system using a class E power amplifier as a power supply, the proposed method simplified the system structure by leaving out a resonant inductor and load matching circuit, which can reduce the power loss of system and improve efficiency. Moreover, the precisely tuning of resonant inductor was not necessary, which improved the stability of the system. The correctness and feasibility of the parameter design method were verified by experiments. The experimental results showed that the output power of the system was increased by 18.7%, the efficiency was increased by 11%, and the transmission distance was up to 0.7 m, which is suitable for wireless power supply of electronics and sensors. [ABSTRACT FROM AUTHOR]

The design and implementation of a simple integrated magnetic (IM) transformer for an LLC resonant converter are presented. The IM transformer with a resonant inductor is implemented using a flexible magnetic sheet. Experimental results are provided to show the validity of the proposed IM transformer. [ABSTRACT FROM AUTHOR]