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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]

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]

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]

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]