High Step-up Topology Research Articles

An extendable soft‐switched high step‐up converter with near zero‐ripple input current suitable for fuel cell‐powered applications

In this paper, an extendable high step-up topology is presented for the low input voltage applications, that is, fuel cell (FC) source. The proposed converter eliminates the pulsating input current and reduces the high input current ripple. Thus, the lifetime of this non-linear source and energy flow is significantly improved. The high output voltage is achieved by using voltage multiplier cells (VMC) and a coupled inductor (CI) with reduced elements. Moreover, an auxiliary circuit is applied due to restoring the energy of leakage inductance in the CI. Therefore, not only all power switching devices are turned on under zero voltage switching (ZVS) but also the input current ripple is remarkably reduced to zero. Furthermore, normalized semiconductors’ voltage stresses are diminished. The reverse recovery problem of diodes and their turn-off power losses at high frequencies are alleviated owing to their zero current switching (ZCS) turn-off. In this paper, the performance of the proposed structure is investigated and compared with the traditional converters considering their voltage gain and voltage stress. Eventually, a 500-W prototype of the proposed converter is built and tested to validate mathematical analyses.

High step‐up interleaved DC‐DC converter for photovoltaic systems

This study proposes a new interleaved high step-up topology based on cross-coupled inductors and voltage multiplier cells (VMCs). Two series capacitors in VMC are employed to raise voltage gain and diminish peak voltage across switches. Thus, low voltage MOSFETs with low on-resistance (R d s ( o n ) ) can be used in the proposed converter. Due to the presence of the leakage inductors in coupled inductors, the falling rate of the output diodes current is controlled and the diode recovery current problem at turn-off can be mitigated. In addition, switches are turned on under ZCS conditions which results in efficiency improvement. Using two-phase topology reduces input current ripple and shares power losses between each phase. The converter is analyzed and its operation is investigated using detailed comparisons. Finally, to confirm the performance of the proposed converter, a 30 V input voltage to 400 V output voltage prototype with the rated power of 220 W is implemented and tested in the laboratory.

Design and Implementation of a New Cuk-Based Step-Up DC–DC Converter

This study proposes a novel modified Cuk converter. The proposed converter attempts to resolve the limitations of the conventional converters, such as voltage gain limitations of a canonical Cuk converter. Therefore, the mentioned improvement has made the proposed converters more compatible for renewable energy applications. Moreover, the increase of the voltage gain in the proposed converter has not impacted the efficiency or the voltage stress of the switches, which is common in other voltage boosting techniques, such as cascading methods. Furthermore, the advantages of a Cuk converter, such as continuity of the input current, have been maintained. The average voltage/current stresses of the semiconductor devices and various types of power losses have been calculated and compared with the existing topologies. Moreover, the non-ideal voltage gain of the proposed converters was compared with the other high step-up topologies. Eventually, the simulation results with PLECS, along with the experiments on an 120 W prototype, have been presented for validation.

Switched-Capacitor High Voltage Gain Z-Source Converter With Common Ground and Reduced Passive Component

Conventional dc-dc Boost converter has limited boost capacity, and its power device suffers high voltage stress. A novel Z-source based dc-dc boost converter featured with high step-up capability and low device voltage stress is proposed in this paper. The proposed topology can also provide a common ground for input and output, which is lacking in the traditional Z-source topology. Compared with other high step-up topologies, the proposed converter can achieve higher voltage gain under the same duty ratio and maintain low voltage stresses on the switch and diode. Moreover, there are fewer passive components in the proposed structure than in other structures. The steady-state analysis for the continuous conduction mode and discontinuous conduction mode is also provided in this manuscript. Finally, a prototype circuit with 40V-60V input voltage, 400V output voltage and 200W output power is implemented in the laboratory. Experiment results confirm the analysis and the features of the proposed converter.

Two‐ and three‐winding coupled‐inductor‐based high step‐up DC–DC converters for sustainable energy applications

This study proposes two configurations for a non-isolated, high step-up, single-switch, coupled-inductor-based DC–DC converter. A coupled inductor and voltage multiplier cells are used in the presented topologies to obtain a high voltage gain. Also, a passive clamp circuit is applied in the topologies to reduce voltage stress of the main power switch. This leads to utilising a power switch with lower on-state resistance, which decreases the conduction loss. Several advantages such as low operating duty cycle, high voltage conversion ratio, reduced voltage stress of semiconductors, low turn ratio of the coupled inductor, leakage inductance energy recovery and high efficiency operation make the presented structures appropriate for sustainable energy applications. The operational principle and steady-state analysis of the suggested topologies in continuous conduction mode are expressed in detail. Also, design procedure and theoretical efficiency of the topologies are presented. Then, the suggested topologies are compared with several similar high step-up topologies to prove their advantages. Finally, the performance and feasibility of the proposed DC–DC converter configurations are confirmed through experimental measurement results of 29 V input and 435 V/213 W and 480 V/238 W output laboratory prototypes at 50 kHz switching frequency.

A Novel Transformer-less Adaptable Voltage Quadrupler DC Converter with Low Switch Voltage Stress

In this paper, a novel transformer-less adjustable voltage quadrupler dc-dc converter with high-voltage transfer gain and reduced semiconductor voltage stress is proposed. The proposed topology utilizes input-parallel output-series configuration for providing a much higher voltage gain without adopting an extreme large duty cycle. The proposed converter cannot only achieve high step-up voltage gain with reduced component count but also reduce the voltage stress of both active switches and diodes. This will allow one to choose lower voltage rating MOSFETs and diodes to reduce both switching and conduction losses. In addition, due to the charge balance of the blocking capacitor, the converter features automatic uniform current sharing characteristic of the two interleaved phases for voltage boosting mode without adding extra circuitry or complex control methods. The operation principle and steady analysis as well as a comparison with other recent existing high step-up topologies are presented. Finally, some simulation and experimental results are also presented to demonstrate the effectiveness of the proposed converter.

High step‐up passive absorption circuit used in non‐isolated high step‐up converter

To obtain a high step-up gain with high efficiency in distributed power sources application, such as photovoltaic (PV) and fuel cells, a passive absorption circuit with voltage step-up character is inserted in the interleaved flyback-forward converter for leakage energy recycle and voltage gain extension. By applying the high step-up passive-clamp circuit, the voltage spike on the metal-oxide semiconductor field-effect transistor is clamped and the energy stored inside the leakage inductance of the coupled inductor can be recycled to get high-output voltage. Moreover, it offers another design freedom to obtain higher voltage-conversion ratio. The operational principle and characteristics of the improved flyback-forward converter are presented, and verified experimentally with a 500 W prototype converter. The proposed high step-up passive-clamp can be widely used in high step-up DC-DC converter applications, and a new high step-up topology is deduced to illustrate the theoretical analysis.

Series-Connected Forward–Flyback Converter for High Step-Up Power Conversion

Recently, small-scale and highly-distributed photovoltaic power sources have been researched for the high generation efficiency even under severe partial shading conditions. However, power conditioning systems for the sources needs high step-up voltage gain due to the low output of the generating sources. This paper presents a newly-suggested high step-up topology employing a Series-connected Forward-FlyBack (SFFB) converter, which has a series-connected output for high boosting voltage-transfer gain. SFFB is a hybrid type of forward and flyback converter, sharing the transformer for increasing the utilization factor. By stacking the outputs of them, extremely high voltage gain can be obtained with small volume and high efficiency even with a galvanic isolation. The separated secondary windings in low turn-ratio reduce the voltage stress of the secondary rectifiers, contributing to achievement of high efficiency. The single-ended scheme is also beneficial to the cost competitiveness. In this paper, the operation principle and design guidelines of the proposed scheme are presented, along with the performance analysis and numerical simulation. Also, a 100 W SFFB DC/DC converter hardware prototype has been implemented for experimental verification of the proposed converter topology.

Ultra Step-Up DC–DC Converter With Reduced Switch Stress

In this paper, a new single-switch nonisolated dc-dc converter with high voltage transfer gain and reduced semiconductor voltage stress is proposed. The proposed topology utilizes a hybrid switched-capacitor technique for providing a high voltage gain without an extreme switch duty cycle and yet enabling the use of a lower voltage and RDS-ON MOSFET switch so as to reduce cost, switch conduction, and turn-on losses. In addition, the low voltage stress across the diodes allows the use of Schottky rectifiers for alleviating the reverse-recovery current problem, leading to a further reduction in the switching, and conduction losses. The principle of operation and a comparison with other high step-up topologies are presented. Two extensions of the proposed converter are also introduced and discussed. Simulation and experimental results are also presented to demonstrate the effectiveness of the proposed scheme.