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In this paper, a single-inductor dual-output (SIDO) dc–dc converter is proposed. The significant feature of the proposed converter is feeding a constant power load in low-voltage side (LVS) port, where even feeding a variable load at LVS does not have any cross regulation to high-voltage side port with the desired approximation. Magnificently, both merits are obtained in open-loop manner, which is an outstanding characteristic in comparison with that of the existed converters. In this paper, soft commutation and soft switching of switches and diodes are investigated along with the aforementioned main novelty. Moreover, detailed theoretical analyses of the proposed SIDO dc–dc converter in continuous conduction mode are presented besides the comparisons with some other structures. Finally, theoretical analyses are verified through a 1500 W experimental prototype results. [ABSTRACT FROM AUTHOR]

In this paper, a new nonisolated high step-down dc–dc converter with ultrahigh step-down conversion ratio is proposed. Advantages of the proposed converter are high step-down ratio, extended duty cycle, reduced switching losses by a converter operation under zero-voltage switching (ZVS) conditions, reduced reverse reco-very losses of diodes by achieved zero-current switching turn-off condition, and reduced voltage spikes by the inherent active-clamping structure of the converter. In this converter, series capacitors and coupled inductors have been used in power path to achieve the low voltage gain and extended duty cycle. By the inherent active-clamping structure of the proposed converter, the leakage inductance energy is totally recovered in the output; therefore, the high voltage spike across the semiconductor devices is suppressed. The switches of the proposed converter can operate under ZVS conditions, which cause reduced switching losses and improved efficiency. In this paper, the converter operating modes are discussed, and a prototype circuit is implemented. Experimental results are presented to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical design procedure for the LLCL and the LCCL filters for grid integration of high-power voltage-source converters. The low switching frequency and stringent limits on grid-injected harmonics in high-power applications lead to large smoothing filters. In order to reduce the size and weight, high-order filters are already proposed and wise design procedures with the main goal of minimizing the overall filter size are being suggested. In this paper, the parameters of the LLCL and the LCCL filters are designed in the per-unit system to satisfy the requirements on the injected grid current and at the same time minimize the overall filter size through minimizing the total energy stored in the filter components. The experimental results of a downscaled laboratory prototype with a low switching frequency prove the effectiveness of the proposed design procedure. [ABSTRACT FROM PUBLISHER]

This paper proposes two coupled-inductors-based Z-source networks, called the modified series and tapped switched-coupled-inductors quasi-Z-source networks (mSSCL-qZSN and mTSCL-qZSN, respectively). These networks offer high voltage gains with less-than-unity winding turn ratios $(n < {\text{1)}}$ , resulting in a reduced inductive element size. Other advantages include a less number of active components and their lower ratings and a higher efficiency. In addition, a lower magnetic core size is required for the proposed ZSNs due to the lower peak magnetizing current. The performance principles and detailed comparative analysis are provided and confirmed through experiments on a 200-W dc–dc converter. [ABSTRACT FROM AUTHOR]

Impedance networks have been already investigated in various literature with the main goals of increasing the attainable voltage gain and reducing the components number. Recently, coupled inductors found popularity because they let converters with lower weight and cost. It seems that coupled inductances are a proper answer to the increasing voltage gain while keeping down the components number. This paper proposes a novel impedance network circuit based on three coupled inductors with a Δ connection. The proposed Δ-source converter offers smaller magnetizing current and winding losses compared to the successful Y-source circuit. Moreover, with the Δ-connected three coupled inductors, the adverse effect of leakage inductance on the converter performance is significantly reduced. The effectiveness of the proposed structure is analytically proved. The theoretical achievements over the conventional Y-source structure are confirmed through extensive simulations and experiments. [ABSTRACT FROM PUBLISHER]

A simple current-feed single-switch forward resonant converter with secondary diode-clamping is proposed for low-power high-density bus converter applications in this paper. The quasi-zero-voltage-switching turn-on and quasi-zero-current-switching (ZCS) turn-off for switch are both achieved. Due to the quasi-ZCS turn-off , the high voltage spike in traditional single forward converter with a reset winding is much reduced. A small diode connected to the output capacitor is utilized to clamp the voltage stress of the switches. The operating principle of the proposed converter is analyzed and a MHz 66 W 24 V-to-12 V prototype with all Si devices is built up. Experimental results show good soft-switching features, and the prototype achieves 95.3% peak efficiency with 270 W/in3 power density. [ABSTRACT FROM PUBLISHER]

Single-phase power factor correction (PFC) ac–dc converters are widely used in the industry for ac–dc power conversion from single phase ac-mains to an isolated output dc voltage. Typically, for high-power applications, such converters use an ac–dc boost input converter followed by a dc–dc full-bridge converter. A new ac–dc single-stage high-power universal PFC ac input full-bridge, pulse-width modulated converter is proposed in this paper. The converter can operate with an excellent input power factor, continuous input and output currents, and a non-excessive intermediate dc bus voltage and has reduced number of semiconductor devices thus presenting a cost-effective novel solution for such applications. In this paper, the operation of the proposed converter is explained, a steady-state analysis of its operation is performed, and the results of the analysis are used to develop a procedure for its design. The operation of the proposed converter is confirmed with results obtained from an experimental prototype. [ABSTRACT FROM PUBLISHER]

During the design phase of a modular multilevel converter (MMC), an accurate loss evaluation of the submodule (SM) plays an important role. In this paper, a method based on the analytical description of the MMC key waveforms that allows to directly obtain the average semiconductor and capacitor losses that each SM will experience is introduced, under different operating conditions or control schemes. To verify the proposed concept, the results are compared with the losses obtained from a switched model with closed-loop control, where the analytical MMC key waveforms are approached in steady state. The proposed method provides a great flexibility and a significant reduction of the simulation/computational time otherwise needed to evaluate SM losses under various operating conditions. [ABSTRACT FROM PUBLISHER]

In this paper, a simple control method of the half-bridge (HB) LLC converter with one additional switch and capacitor in the primary side is proposed for wide-input-voltage applications with the hold-up time conditions. At nominal input, since the proposed method enables the HB LLC converter to operate with large transformer magnetizing inductance, it can reduce the conduction and switch turn-off losses in the primary side, which makes it highly efficient. On the other hand, during the hold-up time, since the proposed method increases the resonant capacitance by turning on one additional switch, the HB LLC converter can obtain high-voltage gain. To confirm the validity of the HB LLC converter with the proposed method, a 325–385 V input and 56 V/350 W output laboratory prototype is built and tested. [ABSTRACT FROM PUBLISHER]

In this paper, an integrated double buck–boost (IDBB) converter is proposed as a high-power-factor offline power supply for power-LED lamps. The IDBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains, providing high power factor and good efficiency. In this paper, the IDBB converter is analyzed, and a design methodology is proposed. It is demonstrated that, with a careful design of the converter, the filter capacitances can be made small enough so that film capacitors may be used. In this way, the converter mean time between failures can be made as high as that of the solid-state lamp. A design example for a 70-W converter supplied from a 230 V/50 Hz mains for street lighting applications is shown. Finally, experimental results from a laboratory prototype are also presented. [ABSTRACT FROM AUTHOR]

This paper presents an efficient single-switch boost-dual-input flyback power factor correction (PFC) converter. To achieve a high power factor, a boost PFC cell operating in discontinuous conduction mode is presented. A dual-input flyback dc–dc module, which consists of parallel primary windings and serial secondary windings, operating in critical conduction mode is introduced for galvanic isolation and valley-switching operation. In addition, the proposed converter features high efficiency because the input power is equally divided, and some power is directly transferred to the load by the dual-input flyback dc–dc module. The remaining power is stored in dc-bus capacitors, and it is closely related to the holdup time. Moreover, the currents in the leakage inductors are absorbed by the dc-bus capacitors through a snubber diode, and they are reprocessed by the dual-input flyback dc–dc module. Consequently, the peak voltage in the MOSFET drain is clamped, and the total power conversion efficiency is improved. To verify the performance of the proposed converter, the operating principles, steady-state analysis, and experimental results from a 48 V, 100 W prototype are presented. [ABSTRACT FROM PUBLISHER]

This paper presents a novel microinverter for a single-phase grid-connected photovoltaic (PV) system. The proposed microinverter consists of a step-up dc–dc converter using an active-clamp circuit with a series-resonant voltage doubler and a high-efficiency inverter with single-switch-modulation step-down converters. The active-clamp circuit provides zero-voltage switching (ZVS) turn-on, recycles the energy stored in the leakage inductance of the transformer, and limits switch voltage stress. Moreover, to remove the reverse-recovery problem of the rectifier diodes, a series-resonant voltage doubler is used. Thus, this whole process provides high efficiency. To improve efficiency and reliability in the proposed inverter, only a single switch is modulated at the switching frequency without a shoot-through problem. A modified controller is also adopted to achieve fast output control. Thus, the proposed PV microinverter has the structure to minimize power losses. The experimental results show a maximum efficiency of 96.2% for a 400-W microinverter. [ABSTRACT FROM PUBLISHER]