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In this paper, a new non-isolated two-input single-output dc–dc converter with high voltage gain is proposed. In the proposed converter, there are two three-winding coupled inductors used to achieve a high voltage gain and ripple-free input currents. The proposed converter has two switches, and their control pulses are the same as the control pulses of the two-phase interleaved converters with a phase shift equal to $\text{180}^{\circ} $. The voltage stresses of switches and diodes are reduced and are always lower than the high output voltage. The proposed converter is extendable to a four-input single-output converter in which the switches have the control pulses the same as those in four-phase converters with phase shifts equal to $\text{90}^{\circ} $. In this paper, the proposed topology is analyzed in all operating modes, and the values of current and voltage stresses of all switches and diodes, voltage gain, and required conditions for input current ripple cancelation are calculated during a switching period. Finally, the accuracy performance of the proposed converter is reconfirmed through experimental results for 225- and 298-W prototypes. [ABSTRACT FROM AUTHOR]

This article develops a series of improved Z-source dc–dc converters to realize additional voltage pumping and high power density through two propositions. Proposition 1 develops two improved positive- and negative-connected Z-source dc–dc converters (IPZSC and INZSC), using the same number of components as in the existing voltage pumping Z-source converter. Based on Proposition 1, Proposition 2 proposes four novel embedded Z-source dc–dc converters (EZSCs) by placing the source in a specifically designed position, which realizes lower voltage stresses across capacitors. Various technical aspects of the proposed EZSCs, including operations, power losses, and small signal stability analyses are detailed in this paper. Besides, comparisons between the proposed series of improved Z-source dc–dc converters and other existing Z-source dc–dc converters are thoroughly made to demonstrate the better performance of the EZSCs. Finally, experiments are conducted to well validate the effectiveness and superiority of the proposed converter circuits. [ABSTRACT FROM AUTHOR]

This article proposes a novel bidirectional isolated dc–dc converter with high voltage gain and wide input voltage, which can be applied to bidirectional power conversion systems. The proposed topology is composed of a bidirectional buck-boost converter and a forward-flyback converter; it has the advantage of higher voltage gain and has continuous current characteristic of the low-side port in step-up and step-down mode. In addition, the proposed topology also has the function of leakage inductance energy recovery, which can improve the efficiency of the converter, reduce the voltage surges on switches, and have the characteristics of zero voltage switching on certain switches. Finally, this paper implements a 500-W bidirectional dc–dc converter to verify the feasibility of the proposed topology. The low-side voltage of the proposed topology is 24, 48, and 55 V; the maximum efficiency in step-up mode are 94.2%, 95.6% and 96.9%, and the maximum efficiency are 92.6%, 94.2% and 94.5% in the step-down mode, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a new structure for a nonisolated boost dc–dc converter is proposed. The proposed converter generates higher voltage gain than some conventional nonisolated boost dc–dc converters. In this paper, the voltage and current equations of the elements and voltage gain in continuous conduction mode and discontinuous conduction mode are extracted. Then, the critical inductance converter is extracted and the current stresses in the switches are calculated. To achieve high voltage gain, a generalized structure based on the proposed structure generates for dc–dc converters. Meanwhile, the root mean square current relations of devices are obtained for an extended structure. Finally, the results of PSCAD/EMTDC software and laboratory prototype are used to reconfirm theoretical concept. [ABSTRACT FROM AUTHOR]

In this paper, a developed structure is proposed for high step-up nonisolated noncoupled inductor based multiport dc–dc converters. The voltage gain per number of devices of the proposed topology is higher than that of similar topologies. This means that, by using the same number of devices, the proposed topology can generate higher gains than other structures. In other words, the proposed topology utilizes less number of devices for producing the same voltage gain, which leads to less total cost, size, weight, and complexity. Despite high voltage gain, the normalized peak inverse voltage (NPIV) on switches/diodes is low. Higher number of input ports leads to higher gains and lower NPIVs on devices. The load energy can be absorbed and stored in first input unit. Modularity, simple structure, continuous input currents, and low input current ripple are the other profits of proposed topology. Low/medium power applications are suggested for the proposed structure. Proposed topology has been explained and operational modes along with steady-state analysis have been discussed. For better verification, the proposed topology has been compared with several multiport high gain converters. Comparison results confirm the advantages of the proposed topology. Finally, the proper performance of the proposed topology has been validated by experimental results. [ABSTRACT FROM AUTHOR]

The ultra-high voltage gain dc–dc converters are extremely required because of the low voltage level of many nonpolluting power resources. This paper proposes an ultra-high voltage gain converter based on an interleave technique and using three-winding coupled inductor and voltage multiplier cell. The interleave technique is useful for reducing the size of the filter components. In the proposed converter, high voltage gain is achieved without extreme duty cycle of solid-state switches. The voltage stress across the semiconductor devices can be reduced by increasing the turn ratio of the secondary of the coupled inductors. In addition, because of the implementation of the interleave structure, peak-to-peak variation of the main input current and switching losses are substantially reduced. The steady-state principles of the proposed converter in continuous conduction mode operation are given. Also, design equations are presented. Validity and performance of the proposed converter are surveyed by simulation and experimental results of a 120 W prototype. [ABSTRACT FROM AUTHOR]

DC grid technology is regarded as a promising solution for future electric networks integrating a great amount of renewable energies. It calls for high-efficiency dc–dc converters with high voltage step-up ratio to interconnect medium-voltage (MV) dc distribution grids and high-voltage (HV) dc transmission grids. This paper presents an isolated bidirectional soft-switching dc–dc converter combining two-level converters in parallel on the MV side and a modular multilevel converter (MMC) on the HV side. A dedicated control method of the proposed converter is presented. By the proposed method, a certain reactive current is injected into the MV side by the MMC to ensure soft-switching on the MV side. The proposed converter presents low power-semiconductor total device rating and low semiconductor losses over a wide power range at variable input and output voltages. Simulation of a 50 kV/400 kV, 400 MW converter is conducted to evaluate semiconductor losses and verify the validity of this work. [ABSTRACT FROM PUBLISHER]

Bipolar repetitive high-voltage pulse generators are commonly used in modern pulsed power applications. Conventionally, bipolar high-voltage pulses can be generated by adding a high-voltage H-bridge at the output stage of a unipolar high-voltage pulse generator which increases complexity and cost of the bipolar high-voltage pulse generator. In this paper, a boost-inverter-based bipolar high-voltage pulse generator with high-voltage gain is proposed. The proposed generator can provide high-voltage bipolar output pulses with the desired specifications from a low input dc voltage. The proposed generator is based on employing two bidirectional boost dc–dc converters, where the load is connected differentially between the boost converters’ output terminals. In the proposed approach, four controlled switches are required. Only two out of these four switches are rated at the high-voltage output level which affects positively the system cost. A detailed illustration of the proposed approach along with the design of its passive components is presented in this study. Simulation and experimental results are used to validate the proposed approach. [ABSTRACT FROM AUTHOR]

Recent advancements in renewable energy have created a need for both high step-up and high-efficiency dc–dc converters. These needs have typically been addressed with converters using high-frequency transformers to achieve the desired gain. The transformer design, however, is challenging. This paper presents a high step-up current fed converter based on the classical Cockcroft–Walton (CW) multiplier. The capacitor ladder allows for high voltage gains without a transformer. The cascaded structure limits the voltage stresses in the converter stages, even for high gains. Being current-fed, the converter (unlike traditional CW multipliers) allows the output voltage to be efficiently controlled. In addition, the converter supports multiple input operation without modifying the topology. This makes the converter especially suitable for photovoltaic applications where high gain, high efficiency, small converter size, and maximum power point tracking are required. Design equations, a dynamic model, and possible control algorithms are presented. The converter operation was verified using digital simulation and a 450-W prototype converter. [ABSTRACT FROM AUTHOR]

For low-cost isolated ac/dc power converters adopting high-voltage dc-link, research efforts focus on single-stage multilevel topologies. This paper proposes a new single-stage three-level isolated ac/dc PFC converter for high dc-link voltage low-power applications, achieved through an effective integration of ac/dc and dc/dc stages, where all of the switches are shared between two operations. With the proposed converter and switching scheme, input current shaping and output voltage regulation can be achieved simultaneously without introducing additional switches or switching actions. In addition, the middle two switches are turned on under zero current in discontinuous conduction mode operation, and the upper and bottom switches are turned on under zero voltage. Due to the flexible dc-link voltage structure, high power factor can be achieved at high line voltage. A 500 W/48 V prototype is designed to serve as the proof of concept, which exhibits 90.8% peak efficiency at low input line voltage. [ABSTRACT FROM AUTHOR]

In this paper, by investigating the topology derivation principle of the phase-shift-controlled three-level dc/dc converters, the modular multilevel dc/dc converters, by integrating the full-bridge converters and three-level flying capacitor circuit, are proposed for the high step-down and high power dc-based systems. The high switch voltage stress in the primary side is effectively reduced by the full-bridge modules in series. Therefore, the low-voltage-rated power devices can be employed to obtain the benefits of low conduction losses. More importantly, the voltage autobalance ability among the cascaded modules is achieved by the inherent flying capacitor, which removes the additional possible active components or control loops. In addition, zero-voltage-switching performance for all the active switches can be provided due to the phase-shift control scheme, which can reduce the switching losses. The circuit operation and converter performance are analyzed in detail. Finally, the performance of the presented converter is verified by the simulation and experimental results from a 2-kW prototype. [ABSTRACT FROM AUTHOR]