The major consideration in dc-dc conversion is often associated with high efficiency, reduced stresses involving semiconductors, low cost, simplicity and robustness of the involved topologies. In the last few years, high-step-up non-isolated dc-dc converters have become quite popular because of its wide applicability, especially considering that dc-ac converters must be typically supplied with high dc voltages. The conventional non-isolated boost converter is the most popular topology for this purpose, although the conversion efficiency is limited at high duty cycle values. In order to overcome such limitation and improve the conversion ratio, derived topologies can be found in numerous publications as possible solutions for the aforementioned applications. Within this context, this work intends to classify and review some of the most important non-isolated boost-based dc-dc converters. While many structures exist, they can be basically classified as converters with and without wide conversion ratio. Some of the main advantages and drawbacks regarding the existing approaches are also discussed. Finally, a proper comparison is established among the most significant converters regarding the voltage stress across the semiconductor elements, number of components and static gain.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2014.0605

Survey on non-isolated high-voltage step-up dc–dc topologies based on the boost converter

This paper introduces a non-isolated high step-up dc–dc converter with dual coupled inductors suitable for distributed generation applications. By implementing an input parallel connection, the proposed dc–dc structure inherits shared input current with low ripple, which also requires small capacitive filter at its input. Moreover, this topology can reach high voltage gain by using dual coupled inductors in series connection at the output stage. The proposed converter uses active clamp circuits with a shared clamp capacitor for the main switches. In addition to the active clamp circuit, the leakage energy is recycled to the output by using an integrated regenerative snubber. Indeed, these circuits allow soft-switching conditions, i.e., zero voltage switching and zero current switching for active and passive switching devices, respectively. The mentioned features along with a common ground connection of the input and output make the proposed topology a proper candidate for transformer-less grid-connected photovoltaic systems. The operating performance, analysis and mathematical derivations of the proposed dc–dc converter have been demonstrated in the paper. Moreover, the main features of the proposed converter have been verified through experimental results of a 1-kW laboratory prototype.

High-Efficiency High Step-Up DC–DC Converter With Dual Coupled Inductors for Grid-Connected Photovoltaic Systems

A new transformerless buck–boost converter with simple structure is proposed in this study. Compared with the traditional buck–boost converter, the proposed buck–boost converter’s voltage gain is squared times of the former’s and its output voltage polarity is positive. These advantages enable it to work in a wider range of positive output. The two power switches of the proposed buck–boost converter operate synchronously. In the continuous conduction mode (CCM), two inductors are magnetized and two capacitors are discharged during the switch-on period, while two inductors are demagnetized and two capacitors are charged during the switch-off period. The operating principles, the steady-state analyses, and the small-signal model for the proposed buck–boost converter operating in CCM are presented in detail. The power electronics simulator (PSIM) and the circuit experiments are provided to validate the effectiveness of the proposed buck–boost converter.

A New Transformerless Buck–Boost Converter With Positive Output Voltage

Renewable sources like solar photovoltaic (PV) and fuel cell stack are preferred to be operated at low voltages. For applications such as grid-tied systems, this necessitates high voltage boosting resulting in efficiency reduction. To handle this issue, this paper proposes a novel high voltage gain, high-efficiency dc–dc converter based on coupled inductor, intermediate capacitor, and leakage energy recovery scheme. The input energy acquired from the source is first stored in the magnetic field of coupled inductor and intermediate capacitor in a lossless manner. In subsequent stages, it is passed on to the output section for load consumption. A passive clamp network around the primary inductor ensures the recovery of energy trapped in the leakage inductance, leading to drastic improvement in the voltage gain and efficiency of the system. Exorbitant duty cycle values are not required for high voltage gain, which prevents problems such as diode reverse recovery. Presence of a passive clamp network causes reduced voltage stress on the switch. This enables the use of low voltage rating switch (with low “ on -state” resistance), improving the overall efficiency of the system. Analytical details of the proposed converter and its hardware results are included.

Design and Analysis of a High-Efficiency DC–DC Converter With Soft Switching Capability for Renewable Energy Applications Requiring High Voltage Gain

In fuel cell vehicles, the output voltage of the fuel cell source is typically much lower than the voltage required by the dc bus, and also this output voltage drops significantly as the output current increases. In order to match the output voltage of the fuel cell source to the dc bus voltage, a new dc–dc boost converter with a wide input range and high voltage gain is proposed to act as the required power interface, which reduces voltage stress across the power devices and operates with an acceptable conversion efficiency. A prototype rated at 300 W/400 V has been developed and the maximum efficiency of the proposed converter was measured as 95.01% at 300 W. Experimental results are presented to validate the effectiveness of the proposed converter.

/pdf/dc-dc-boost-converter-with-a-wide-input-range-and-high-bsz2f87uj8.pdf

DC–DC Boost Converter With a Wide Input Range and High Voltage Gain for Fuel Cell Vehicles

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.

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

In this paper, a transformer-less interleaved four-phase current-fed converter with high voltage 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 can not only achieve high step-up voltage gain 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 four interleaved phases for voltage boosting mode without adding extra circuitry or complex control methods. The operation principle and steady analysis of the proposed converter are discussed. Finally, some simulation and experimental results are also presented to demonstrate the effectiveness of the proposed converter.

Ching-Tsai Pan

Papers

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

A transformer-less interleaved four-phase current-fed converter with new voltage multiplier topology