High Step-up Converter Research Articles

A Hybrid Structured High Step-Up DC–DC Converter for Integration of Energy Storage Systems in Military Applications

In the military, the utilization of low power density converters to interface the increasing number of electronic gadgets such as radios, remote controls, tablets, night-vision goggles and wrist-mounted display central computer systems are adding up the load burden on the soldiers. Hence, a hybrid structured high step-up DC-DC converter is proposed in this paper with minimal number of active and passive devices. The novel arrangement of the switched inductor (SI) and switched capacitor (SC) in a hybrid combination has led to the development of the proposed converter which has the advantage of both SI and SC configurations. As a result, high gain is possible with less voltage stress across the switch, natural voltage clamp on the switch and reduced input ripple current compared to existing topologies. The paper describes the operational principle, steady-state analysis and comparative features of the proposed converter with recently reported converter. A 500W prototype is developed with a power density of 446.42 kW/m3 and the experimental results were observed to validate the theoretical analysis of the proposed high step up converter.

Double Dual High Step-Up Power Converter with Reduced Stored Energy

This paper introduces a dual-switchhigh step-up DC-DC power converter. The proposed converter features a high step-up voltage gain, relatively low cumulative stored energy over its inductors, low voltage stress on the active switches, and high efficiency, even at a relatively high duty ratio. An assessment of the proposed converter against conventional boost and a high step-up power converter is presented in terms of steady-state time, voltage gain, stored energy over its inductors, and efficiency. The assessment shows a reduction of 81.25% and 62.5% of stored energy in inductors to comply with the same operational conditions. Simulation and experimental results are provided to validate the benefits of the proposed dual-switch high step-up power converter.

Coupled Inductor-Based Single-Switch Quadratic High Step-Up DC–DC Converters With Reduced Voltage Stress on Switch

In this article, two single-switch quadratic boost converters based on a three-winding coupled inductor (CI) are proposed. These converters provide a high voltage gain in a low duty cycle, reduced voltage stress on the power switch, continuous input current with a low <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">di/dt,</i> higher design flexibility, and limited current falling rate on the voltage multiplier diodes to minimize the reverse recovery loss. Moreover, the first proposed converter has two capacitors in the output reducing the need for a bulky output capacitor, while the second proposed converter has higher utilization of the CI and is able to provide a higher voltage gain. The operation principle and theoretical analysis, such as voltage stress, current stress, effect of leakage inductances on the voltage gain, and design considerations are presented in this article. Furthermore, the superiority of the proposed converters over the competitive high step-up quadratic converters are justified through a comparison study. Finally, a 300-W, 30- to 400-V laboratory experimental setup is implemented to validate the theoretical analysis.

A Novel ZVS/ZCS Push-Pull LC Resonant DC-DC Converter for Energy Sources

In this paper, a novel soft switching push-pull LC resonant DC-DC converter for energy sources is presented. In a high step-up converter, the input of primary side possesses low voltage and high current, so the losses caused by the current account for most of the total power loss. At the same time, the high-voltage stress of the high-voltage output components on the secondary side is also a major problem. Therefore, a high-gain isolated push-pull converter with a secondary-side resonant circuit is proposed, so that the primary-side switches have zero voltage switching (ZVS) and the secondary-side diodes have zero current switching (ZCS). The push-pull structure can reduce the number of active switches, so that the total power loss on the primary side can be reduced. The converter has a resonant tank circuit arranged between the secondary side of isolation transformer and the high-voltage output rectification module. The high-voltage output rectifier module adopts a full-bridge architecture suitable for high-voltage coupling connection. The low-side power switching module adopts a push-pull architecture suitable for low-voltage and high-current applications. The resonant tank circuit uses an inductor–capacitor (LC) structure to improve the resonant tank circuit, which achieves soft switching during power transfer, increasing the efficiency of the converter and improving the electromagnetic compatibility. The main advantage of this technology is that the secondary-side leakage inductance of transformer and the resonant capacitance are connected in series to achieve ZVS for switches and ZCS for diodes. Finally, a prototype of a high-gain push-pull resonant converter was established. The converter was operated at a fixed switching frequency of 135 kHz and a duty cycle of approximately 0.5. The efficiency of the converter can reach 97.1% under experimental tests at an output voltage of 400 V and a rated output power of 500 W.

A High Step-Up Isolated DC-DC Converter Based on Cascaded Greinacher Voltage Multiplier

High step-up converters are required and used in photovoltaic applications, due to low voltage of photovoltaic modules. In this paper, an isolated dc-dc high step-up SEPIC with a Greinacher voltage quadrupler cell is proposed. It has the advantage of continuous input current, high efficiency, high voltage gain, isolation and demands a single switch, being suitable for low power grid-tie photovoltaic systems. The derivation of converter, the operating principles and steady-state analysis are presented, including the detailed analysis of resonant stage, where the value of primary side capacitor is taken into account. Besides that, effects of transformer winding capacitances on converter operation are investigated. Experimental results on a 37.4/400 V, 50 kHz and 200 W prototype are presented to validate the proposed topology and concept, where the maximum efficiency obtained is 97.75%.

Decoupled control of a high step-up multi-input converter for renewable energy applications

This paper focuses on the development and control of a non-isolated high step-up multi-input dc–dc converter for renewable energy applications. The converter has non-pulsed input currents and high voltage gain owing to the input inductors and a switched-capacitor (SC) network. In a two-input case, there are only two low-side switches controlled independently for adjusting individual input power levels and another low-side switch for operating the SC network. Steady-state analysis and dynamic modelling of the converter are provided. Design procedures regarding the hardware and decoupled control system dealing with the interactions of the control loops are given. After a benchmark study, a laboratory prototype rated at 200-W validates the analysis and tests the control system when subjected to step changes.

Small-signal model of two-phase interleaved coupled inductor-based high step-up gain converter in DCM

Small-signal model of two-phase interleaved coupled inductor-based high step-up gain converter in DCM

Soft-Switched Boost–Cuk-Type High Step-Up Converter for Grid-Tied With Half-Bridge Inverter

In this study, a novel two-stage grid-tied high step-up inverter is proposed. The first stage (dc–dc) is a combination of boost and cuk converters as well as a simple dc-link voltage balancing circuit. The balancing circuit is connected in series with the output of the cuk converter to compensate for the output voltage difference between boost and cuk converters. The second stage (dc–ac) comprises a conventional half-bridge inverter. The ground leakage current is eliminated in the proposed topology by the simultaneous grounding of the photovoltaic (PV) module and the grid. A lossless passive snubber with the minimum elements is also proposed and analyzed to provide the soft-switching conditions. In this snubber circuit, the snubber capacitance discharges to the output dc link to decrease the converter circulation losses. The main attributes of the proposed dc–dc converter with lossless passive snubber are the simple structure of the dc–dc converter and snubber circuit, simple control scheme, and high efficiency. Various operation modes of the proposed topology are theoretically analyzed and investigated. The experimental results substantiate the effectiveness and performance of the proposed boost–cuk-based high step-up inverter with the lossless snubber.

A new high step-up active clamp DC-DC converter with high efficiency

In this paper, a new high step-up converter with a simple structure is presented. The auxiliary circuit of the proposed converter is in the form of active clamp, which provides soft switching condition under zero voltage for the main and auxiliary switches, hence the converter has high efficiency. Since the auxiliary switch added in the converter works as an active clamp and has a complementary command with the main switch, the proposed converter is not complicated in terms of the control circuit and does not need to design a new control circuit. This converter has a high voltage gain that provides a high output voltage with a lower duty cycle, so it is suitable for a new energy production system such as a solar system. The proposed converter has been fully analyzed and in order to prove the theoretical analysis, an experimental prototype has been implemented and tested at a power of 500 W, which in this power an efficiency of about 97.3% has been obtained.

High Step-up SEPIC Converters Based on a Family of Coat Circuit

High Step-up SEPIC Converters Based on a Family of Coat Circuit

Three-Terminal Gain Cells Based on Coupled Inductor and Voltage Multiplers for High Step-Up Conversion

A generalized methodology for creating gain cells with three terminals is proposed in this brief. The gain cells are based on inductor coupling and voltage multiplier techniques and are applied to the classical dc-dc Boost converter. When compared with conventional gain cells already described in the literature, the proposed ones are able to provide higher step-up gains with the same number of components. Additionally, they also require lower magnetizing inductances to ensure their operation in continuous-conduction mode, which may reduce the volumes of the coupled inductors. To illustrate the application of the proposed gain cells, an example of high step-up dc-dc converter is created and its operation principle is analyzed. A 200-W prototype concerning to this converter is built and tested, validating the proposal.

High Linear Voltage Gain in QZNC Through Synchronizing Switching Circuits

The solar powered systems require high step-up converter for efficient energy transfer. For this, quasi-impedance network converter has been introduced. The quasi-impedance network converter (QZNC) is of two types: type-1 and type-2 configuration. Both the type-1 and type-2 QZNC configurations have drooping voltage gain profile due to presence of high switching noise. To overcome this, a new quasi-impedance network converter synchronizing the switching circuit with low frequency noise has been proposed. In this paper, the proposed QZNC configuration utilizes the current controlling diode to prevent the output voltage drop. Thus, the suggested topology provides linear high voltage gain profile, low load voltage ripple, and reduced impedance network stress and device stress. Therefore, the efficiency of proposed QZNC has been improved. The topology description, working principle, parameter design and comparison with traditional converters are illustrated. And finally, both simulation and practical results are presented to confirm the converter characteristics and performance. From the results, it has been found that the performance of the suggested topology is better as it achieves a higher efficiency of 81% and hence, it is suitable for high power applications.

High Step-Up SEPIC-Based Trans-Inverse DC–DC Converter With Quasi-Resonance Operation for Renewable Energy Applications

This article proposes a new single switch trans-inverse high step-up converter applicable in sustainable sources of energies such as photovoltaic (PV) and fuel cell (FC). Through developing a single-ended primary-inductor converter by a three-winding built-in transformer (BIT) mixed with a switched-capacitor voltage multiplier cell, high voltage gains as well as low voltage stress across the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> can be achieved to reduce the required duty cycle and the conduction losses. The third winding of the BIT acts in a trans-inverse manner whose turns ratio should be lower than unity. Hence, with a lower number of windings the voltage gain can also be improved. Furthermore, the quasi-resonance operation of the proposed converter, reduces the associated switching losses of the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> and also guarantees zero current switching of diodes through the whole switching cycle. Meanwhile, low input current of the proposed converter serves as an interesting feature to maintain PV and FC lifetime. The detailed steady-state analysis of the proposed high-efficiency converter is presented with an extensive performance comparison to explore its advantages. Finally, a 200-W prototype with 20–250-V voltage conversion is developed in the laboratory to examine the carried steady-state analysis.

The Resonant Modular Multilevel DC–DC Converter Adopting Switched-Inductor Cells for High Step-Up Ratio

With the prosperous development of distributed renewable energy power generation, high-voltage direct-current (HVDC) system has evolved into large-scale practical applications from the initial stage, and high step-up conversion dc–dc converters have become a core technology to promote the development of HVDC system. This article proposes a new resonant modular multilevel dc–dc converter (MMDC) based on the conventional boost converter. The single-switch and diode of the conventional boost topology are replaced by submodules (SMs), which are clamped by floating capacitors, and the inductor is replaced by switched-inductor (SL) cells. The phase-shifted pulsewidth modulation (PS-PWM) is applied to regulate the state of SMs, i.e., inserted state or bypassed state, to ensure that there is a constant number of SMs supporting the output voltage at any time. The converter is operated in resonant mode with resonance between capacitors of SMs and the upper arm inductor. The step-up conversion ratio is dependent on the inductors charging ratio, the number of SMs, and SL cells. Hence, more regulation schemes are available. The proposed converter possesses the advantages of MMDC and has the inherent-balancing capability of SM capacitor voltages without additional complex balancing control. The structure of the converter, operating mode analysis, parameter design, and comparison with other MMDCs are presented, which have been verified by simulated and experimental results.

Nonisolated High Step-Up DC–DC Converter With Passive Switched-Inductor-Capacitor Network

In this article, a nonisolated dc–dc high step-up converter with passive switched-inductor-capacitor network is proposed, which is applicable for the required high-gain voltage low-power applications, such as battery-powered LED lighting systems and high-intensity mobile discharge lamps. The proposed circuit can produce higher gain voltage with small duty cycle, which decreases the voltage stress and conduction power loss on the active switches. In contrast to other nonisolated dc converters, by using the same or analogous number of passive/active components in circuit topology, the proposed topology has lower voltage stresses across capacitors and diodes and lower inductor current stresses. Therefore, the efficiency and reliability of the circuit topology can be ameliorated. The theoretical principle, parameter design guideline, small-signal dynamic analysis, power loss analysis, and performance comparison with other dc–dc nonisolated converters have been implemented. Finally, a 200-W experimental setup is built and tested with an input dc voltage of 36–60 V and an output voltage of 200 V to validate the aforementioned merits of the proposed circuit.

A Single Switch High Step-Up DC-DC Converter Based on Tri-Winding Coupled Inductor for Renewable Energy Applications

This article introduces a novel nonisolated single-switch high step-up DC-DC converter using a tri-winding coupled inductor (TWCL) for renewable energy applications such as PV systems. Also, the voltage multiplier cell (VMC) is used to attain a high voltage gain. The used VMC acts as a passive clamp circuit and reduces the voltage stress across the power switch. So, a low voltage-rated power switch can be used in the presented converter. The suggested topology uses only one power switch with low on-state resistance (RDS-ON), which leads to a simple control circuit and decreases the conduction losses. Highefficiency, operating with low duty cycle, low peak voltage over semiconductor elements, low turns ratio, the number of the coupled inductor, and high voltage conversion ratio are the significant benefits of the recommended DC-DC converter. To show the achievement of the presented structure, operational mode principles, steady-state, efficiency calculations, and comparison results are provided. Finally, a 120 W experimental prototype with 200 V output voltage and 50 kHz switching frequency is built to prove the usefulness of the suggested high step-up converter. The efficiency is measured 92.11% at rated power.

Comprehensive Analysis of Voltage Step-Up Techniques for Isolated SEPIC

High step-up converters are often used in photovoltaic applications due to low voltage of photovoltaic modules. In this paper, a study of several voltage step-up cells added on primary and secondary sides of an isolated dc-dc SEPIC (single ended primary inductor converter) is made, in order to increase its static gain and synthesize a family of converters. To perform this study and select the most appropriate resulting converter, theoretical and comparative analyzes are accomplished. They include a brief description of each converter, tables and curves with relevant information, such as voltage gain, voltage stresses and component count, and the identification of the use of coupled inductor or transformer based on the analysis of dc magnetizing current. Moreover, theoretical analysis and experimental results on a 50 kHz and 200 W prototype of selected isolated SEPIC with voltage doubler cell are presented to validate the proposed topology and concept.

A Three-Winding Coupled-Inductor-Based Dual-Switch High Step-Up DC–DC Converter for Photovoltaic Systems

This article proposes a new high step-up dc–dc converter for photovoltaic applications. A dual-switch structure with a three-winding coupled inductor (3WCI), whose secondary and tertiary windings are integrated with switched-capacitor cells, is adopted to achieve a high-voltage gain with a small duty cycle, thus avoiding an extremely high duty cycle. The input current is continuous, and the voltage gain could be adjusted by two parameters: the switches’ duty cycle and 3WCI's turns-ratio, thus increasing the design flexibility of the proposed converter. In addition, low-voltage-rated <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s with small <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state resistances are selected, and their losses are reduced due to the low-voltage stress and small duty cycle of the switches. Moreover, the current-falling rates of most diodes are controlled by the 3WCI's leakage inductances. The operating modes, detailed analyses, and design considerations for the proposed converter are presented. Additionally, comparisons with other high step-up converters are provided. A 200-W laboratory prototype with an output voltage of 400 V is fabricated and tested using various input voltages to validate the theoretical analyses.

ZVT High Step-Up Boost Converter With Wide Input Voltage and Wide Output Power for Renewable Energy Applications

In this article, a high-efficiency, high step-up dc–dc converter is introduced by utilizing a new soft-switching circuit based on the zero-voltage transition (ZVT) technique. Soft-switching performance is independent of the output load and input voltage. The simple auxiliary circuit benefits from a low number of components. The resonant circuit comprises merely one switch and one small capacitor, and in comparison to the existing ZVT high step-up converters, no extra auxiliary diode and resonant inductor are used to provide soft switching. The proposed auxiliary circuit can be applied to coupled inductor (CI)-based step-up topologies, because of exploiting the leakage inductance of the CI cell in the resonant network. Providing soft-switching performance for all the semiconductor elements alleviates the reverse recovery and switching losses, which considerably enhances the efficiency. The proposed topology is a competitive structure in terms of efficiency, voltage gain ratio, and the number of components due to the mentioned features. The theoretical results are validated on a 200-W laboratory prototype with a 400-V output voltage.

Novel Modified High Step-Up DC/DC Converters with Reduced Switch Voltage Stress

This paper presents the improved switched inductor unit and new step-up DC/DC converters with reduced switch voltage stress and high voltage gain. The proposed switching-inductor unit is composed of 1 switch, 2 diodes, and 2 inductors, which can realize the step-up function. Through comparison, the better topology is selected from the proposed converters, which is named the double-switch high step-up (DS-HS) converter. The CCM operating principles and voltage gain of the DS-HS converter are analyzed. Then, the influences of nonideal components, efficiency analysis, small signal modeling and control, and design criteria of components are discussed. The comparison of the converters is given, and the loss of the DS-HS converter is lower through theoretical derivation, which shows that the DS-HS converter has the advantages of high voltage gain, low voltage stress, and high efficiency. Finally, in order to verify the effectiveness of the DS-HS converter, simulation and experimental results are given, and the efficiency of the DS-HS converter can reach 96.15%.