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A DC‐DC converter with high boost and low switching voltage stress is proposed by combining switched capacitor (SC) and coupled inductor (CL) techniques based on a conventional boost circuit. The design methodology of this converter includes substituting SC for a single switch in the boost converter, combining CL, and integrating a resonant boost circuit for absorbing leakage inductance. The improved power switch topology in this design has lower voltage stress, lower diode current stress, fewer total components, and common ground than other conventional DC‐DC converters. The operating modes and steady state analysis of the converter are provided in terms of leakage inductance utilization, with component stress derivation and theoretical efficiency analysis. In addition, comparisons with other dc‐dc converters are made. Subsequently, experiments were conducted on a 200 W DC‐DC converter prototype to verify the reliability of the converter. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to introduce a new high step-up/down buck-boost converter with a minimum number of switches which provides the benefit of having the continuity of the input/output current. This single-switch semi-quadratic converter is suitable for high step-up applications while being able to provide step-down voltage gains. Also, by applying some minor changes to the circuit elements, another single-switch buck-boost converter is suggested which has two operative outputs with different voltage gains. One of the outputs of this topology has quadratic buck-boost converter voltage gain which is appropriate for high step-up/step-down applications. The other output could vary from input voltage to minus infinity, ideally. After studying the steady-state operation of the proposed converters in Continuous Conduction Mode (C.C.M), the simulation results are presented. In addition, a comparison among related converters proposed in the literature is made. Finally, experimental results are evaluated by implementing a laboratory prototype of the proposed converter in both step-down and step-up modes. Theoretical, simulation, and experimental results are compatible with each other.

An interleaved Buck-Boost-Zeta converter with the coupled inductor multiplier cell and zero input current ripple is proposed in this paper, which is suitable for high step-up applications such as the photovoltaic generation system. By integrating the Buck-Boost converter with the Zeta converter and adding the coupling inductor voltage multiplier cell and the auxiliary input inductor, the proposed converter achieves very high voltage gain and very low switch voltage stress. At the same time, very low input current ripple and continuous output current can be achieved, which is friendly to photovoltaic arrays and DC-bus. The leakage inductance energy is absorbed by the passive clamp circuit, the zero-current-switching (ZCS) turn-on of the switch is achieved and the reverse recovery problem of the diode is alleviated. The operation principles and performances of the proposed converter are analyzed in detail. The proposed converter can further improve the voltage gain by adding different voltage multiplier cells and their general structures are given. A prototype with 32V input and 400V output was built to verify the theoretical analysis.

This article presents a single-switch high step-up quadratic DC-DC converter for DC microgrid applications. The quadratic boost converter is integrated with switched capacitor cell along with coupled inductor to achieve high gain at reduced duty ratio. The switched-capacitor cell is composed of two diodes and two capacitors. The capacitors charge in parallel and discharge in series to increase the converter’s gain. The coupled inductor turn ratio can be increased to elevate the converter’s gain further. The inductor at the input minimizes the current ripples and makes the input current to be continuous. Moreover, the proposed converter works as a passive clamp circuit to minimize large voltage spikes across the switch (MOSFET) and it has low $R_{ds}$ (on-state) to minimize the conduction losses. As a result, the device’s rating improves, losses decrease, and it becomes less expensive to switching devices of the converter. The energy leakage of the coupled inductor is recycled to the output capacitor, it can reduce the reverse recovery issue in diodes and increases efficiency of converter further. The proposed converter working principle and its analysis are explained with different operating modes. The performance of the converter is validated with laboratory hardware setup with rating of 160W. Here, the input and output voltages are considered at 20V and 400V, respectively. Finally, the superiority of the proposed converter is compared with existing literature in terms of gain, stress across various components, switching performance and efficiency.

The DC microgrid with energy storage cells has strong stability, simple control, and a convenient power supply for DC loads, increasingly becoming the grid-connected structure of distributed generation systems. This paper presents an isolated high voltage gain soft-switching dc-dc converter suitable for DC microgrid applications. The converter comprises a dual-switch quasi-z-source network, multiplier voltage cell, and transformer. It has advantages such as high voltage gain, zero voltage switching (ZVS) of switches, zero voltage zero current switching (ZVZCS) turn-on and turn-off of diodes, and low input ripple current. The converter can achieve high voltage gain with an appropriate duty cycle and transformer turns ratio, reducing leakage inductance of transformer, which decreases the power loss and voltage spike of switch. Soft-switching of active devices increases the efficiency and decreases the output voltage ripples of the converter. The steady-state characteristics of the converter, voltage and current stress of components, the efficiency of the converter, and the selection of converter parameters are analyzed in detail. Finally, a 200 W experimental prototype is built in the laboratory for experimental verification, and the experimental results are consistent with the theoretical analysis.

Abstract This article proposes an interleaved high step‐up DC–DC converter topology designed for renewable energy applications, featuring an ultra‐high voltage conversion ratio. The converter employs an interleaved structure, resulting in a low peak‐to‐peak ripple in the input source current, which is particularly advantageous for solar PV sources. To enhance the output voltage, the topology utilizes voltage multiplier cells (VMC) and coupled inductor techniques. Two coupled inductors with three windings are integrated into the proposed topology, with the secondary and tertiary windings combined with VMC. This combination effectively reduces the maximum voltage stress across power switches, enabling the use of low‐rated and cost‐effective power switches for implementation. The article offers comprehensive operation modes and steady‐state analyses to demonstrate the converter's performance. A comparison is made between the suggested structure and other similar converter topologies. To validate the mathematical analysis, a 200‐W prototype is constructed, operating at a frequency of 25 kHz and achieving a voltage conversion range of 20 to 409 V. The experimental results are presented to support the findings.

In this paper, the combination of a high step-up boost converter with extended voltage multiplier cell and isolated SEPIC converter with a series output module is presented. Since these converters use the same current source in their inputs, they can share the common parts, so the structure of the proposed converter is simple. In this converter, the high frequency transformer used in the SEPIC converter and the inductor of the extended voltage multiplier cell are coupled, so the volume of the magnetic parts is reduced. In addition, an active-clamp circuit is used to solve the problem of leakage inductor and achieve to Zero Voltage Switching (ZVS) turn on/off for switches and ZCS for diodes. Compared to its high step-up counterpart, the proposed converter has the following: (1) distributed voltage stress on the diodes and voltage of the output capacitors are fair. (2) Higher voltage gain. (3) Voltage stresses on the diodes are lower and the reverse-recovery problem of the diodes is eliminated. (4) Minimum root mean square (RMS) leakage inductor current. The operational principle and characteristics of the proposed converter are presented, and in order to verify the proposed converter, a 200 W, 20–400 V prototype converter is implemented and experimental results are provided. [ABSTRACT FROM AUTHOR]

This article proposes an interleaved high step‐up DC–DC converter topology designed for renewable energy applications, featuring an ultra‐high voltage conversion ratio. The converter employs an interleaved structure, resulting in a low peak‐to‐peak ripple in the input source current, which is particularly advantageous for solar PV sources. To enhance the output voltage, the topology utilizes voltage multiplier cells (VMC) and coupled inductor techniques. Two coupled inductors with three windings are integrated into the proposed topology, with the secondary and tertiary windings combined with VMC. This combination effectively reduces the maximum voltage stress across power switches, enabling the use of low‐rated and cost‐effective power switches for implementation. The article offers comprehensive operation modes and steady‐state analyses to demonstrate the converter's performance. A comparison is made between the suggested structure and other similar converter topologies. To validate the mathematical analysis, a 200‐W prototype is constructed, operating at a frequency of 25 kHz and achieving a voltage conversion range of 20 to 409 V. The experimental results are presented to support the findings. [ABSTRACT FROM AUTHOR]

The main objective of this study was to develop a method for the maximum power point tracking (MPPT) of photovoltaic module arrays (PVMAs) implemented using two proposed improved grey wolf optimization algorithms (GWOAs). A high-step-up soft-switching converter combined with lost-cost voltage and current sensors was adopted to realize MPPT. This reduced the converter switching losses and cost. Furthermore, in the improved GWOAs, iteration parameters were automatically adjusted online on the basis of the slope of the power--voltage (P-V) curve of the PVMA. In addition, 0.8 times the maximum power point (MPP) voltage of the PVMAs under standard test conditions was set as the starting voltage for conducting global MPPT. Lastly, by verifying the proposed improved GWOAs with actual test results, where multiple peak values were generated in the P-V characteristic curve of the PVMA by shading, we demonstrated that all MPPs could be tracked successfully, and the two improved GWOAs reduced the tracking time by at least 18.6 and 33.3% compared with that of the conventional GWOA. Therefore, the improved GWOAs exhibit superior tracking speed and stability. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a new ultra high step‐up soft‐switching DC/DC converter using coupled inductor and interleaved technique is presented. The primary side of the coupled inductors in up section and down section will be charged by the input power supply. The stored energy of the coupled inductors (at primary and secondary sides) is discharged to the output capacitors in up and down sections. Also, the capacitors on the coupled inductors path have clamped capacitors that cause the voltage stress across the power semiconductors to be low. Al diodes in up and down sections except output diodes are working at zero current switching turn‐off. Therefore, the reverse recovery problems of the proposed converter will be majorly solved. Therefore, power losses of the proposed converter will be decreased by using switches with lower on‐state resistance RDS(on) and lower rating power diodes. In addition, the leakage inductor causes to exclusive the current falling balance of the output diodes, significantly. In order to clarify the main advantages of the proposed converter, comparison between the proposed converter and other structures is provided. Finally, the proposed converter with turn ratio N(N2/N1) = 2 in about 300 W with operating 50 kHz is tested with real‐time TYPHOON HIL‐404 emulator in the laboratory.

Summary: This article presents three topologies of high‐voltage gain DC–DC converter based on boost converter with three‐winding coupled inductor. Before proposing these converters, a cascade cell connection synthesizing approach was initially evaluated. This approach allowed the generation of a set of six high‐voltage gain converters. However, only three converters present good performance. Thus, to demonstrate the advantages, disadvantages, and limitations of each converter, the following characteristics are evaluated: the operating principle of the proposed converter, gain of voltage, voltage, and current stress, in addition to the factors of total voltage stress and total current stress, factors that indicate the choice of components with lower intrinsic resistances. To validate these analyses, a 250 W, 30 V/400 V prototype was implemented experimentally, reaching a maximum efficiency of 96%. [ABSTRACT FROM AUTHOR]

A non-isolated high gain DC–DC converter with magnetic coupling and a VM circuit is proposed in this study. By the use of the appropriate coupled inductor turn ratio, the output voltage of the recommended topology can be raised. The VM circuit is used to boost the voltage gain even further as well as to clamp the voltage spike across the switch, which results in a lower voltage on the switch. As a result, a MOSFET switch with a lower ON-state resistance (RDS-ON) is used which, in turn, causes the conduction losses to be reduced and the entire system efficiency to be raised. Another advantage of the proposed structure is the ZCS of the diodes, which reduces the voltage drop losses caused by the regenerative diodes. The function modes analysis and the theoretical equations are accomplished. A comparison survey with other prior works is being developed to investigate the competency of the proposed converter. Based on this, the higher voltage gain and efficiency as well as the lower voltage stress on the semiconductors can be achieved by the proposed converter compared to the other converters. The effectiveness of the proposed converter is confirmed by the experimental results at a laboratory-scale operating under 150 V output voltage with a 96% efficiency at the 150 W full load and a 25 kHz switching frequency. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a high step‐up DC–DC converter using coupled inductor voltage multiplier cell and differential connection method. The proposed converter is obtained by differentially connecting a Cuk converter and a Buck‐Boost converter and integrating a coupled inductor voltage multiplier cell. The control mode of the two switches adopts interleaved control and the proposed converter has higher voltage gain. The diode‐capacitor branch in the shared topology is used as a passive clamping branch to reduce the maximum voltage stress of switches. The working principle of the proposed converter is analyzed and its performance parameters and boundary conditions are given. The voltage gain of the converter can be improved by adding different voltage doubling structures and the general topology of the proposed converter is given. The effect of leakage inductance on the performance of the proposed converter is analyzed. Finally, a 300‐W prototype was built and verified the theoretical analysis.

This paper proposes a single-switch integrated Sepic converter with a Y-source coupled inductor that can be applied to the output of photovoltaic (PV) arrays. The three-winding coupled inductor has higher voltage regulation efficiency, and the three-port tap of the y-source is easier to integrate with other structures to form a composite power cell. The proposed topology gives a new type of Y-source voltage multiplication cell. While ensuring the continuous input current, it can flexibly adjust the voltage gain, increase the power capacity, and reduce the voltage stress of the switch. The diode-capacitor branch in the integrated topology is used as a clamp to suppress the voltage shock while using the absorbed leakage energy to achieve soft-switching characteristics, mitigate diode reverse recovery, and improve the efficiency of the converter. A detailed theoretical analysis of the converter is carried out, and the general extension of the topology and the extension of the converter family are given. Finally, a 150 W prototype was built to verify that the converter can achieve high gain under high efficiency of 94.3%.

In this study, the authors propose a non-isolated high step-up interleaved DC/DC converter that can be applied to sustainable energy system. The proposed converter achieves high voltage gain by employing a coupled inductor and switched capacitor method based on an interleaved boost converter. The two coupled inductors connected in parallel with the input side have a distinct structure. Specifically, a single coupled inductor has a primary side and a secondary side connected in series, and it is further connected in parallel with an output side switched capacitor circuit. The switched capacitor circuit increases the voltage gain by being charged in parallel and discharged in series through the coupled inductor. The leakage inductor energy of the coupled inductor can be regenerated to the output side through the passive clamp circuit’s performance. Moreover, it is possible to select devices with low voltage stress and on-state resistance of the switches, which results in reduced loss and size while alleviating the reverse recovery problem of diodes. The steady-state analysis and operation principle of the proposed converter are thoroughly explained and verified through a prototype circuit with 20V input voltage, 400V output voltage, and 320W level output power.

In this paper, a new ultra high step‐up soft‐switching DC/DC converter using coupled inductor and interleaved technique is presented. The primary side of the coupled inductors in up section and down section will be charged by the input power supply. The stored energy of the coupled inductors (at primary and secondary sides) is discharged to the output capacitors in up and down sections. Also, the capacitors on the coupled inductors path have clamped capacitors that cause the voltage stress across the power semiconductors to be low. Al diodes in up and down sections except output diodes are working at zero current switching turn‐off. Therefore, the reverse recovery problems of the proposed converter will be majorly solved. Therefore, power losses of the proposed converter will be decreased by using switches with lower on‐state resistance RDS(on) and lower rating power diodes. In addition, the leakage inductor causes to exclusive the current falling balance of the output diodes, significantly. In order to clarify the main advantages of the proposed converter, comparison between the proposed converter and other structures is provided. Finally, the proposed converter with turn ratio N(N2/N1) = 2 in about 300 W with operating 50 kHz is tested with real‐time TYPHOON HIL‐404 emulator in the laboratory. [ABSTRACT FROM AUTHOR]

This work proposes a high step-up interleaved dc/dc topology utilizing a VM (voltage multiplier) cell suitable for PV applications. The VM cells D/C (Diode/Cap.) are cascaded among the phases to approach a high voltage gain. Besides, the voltage converting ratio of the presented structure can be improved by extending the VM cells and it also leads to drop in the normalized voltage stress throughout the switches and some diodes. Therefore, by utilizing a semiconductor (Switch/Diode) with a lower rating leads to a decline in system losses. Also, the efficiency of the suggested topology will be considerable and the overall cost can be decreased. To elaborate on the main benefits of the proposed topology, a comparison has been made across other literature regarding the efficiency, peak voltage throughout the semiconductors and voltage ratio of the converter. To prove the accuracy principle of operation of the suggested converter, two prototypes (for n=1, 2 stages) were built and tested at 350 W and 453 W with an operating frequency of about 40 kHz performed.

High step-up DC-DC converters are considered as main components of some low-voltage and low-power fuel cell power system applications. A new DC-DC converter topology based on a two-stage switched capacitor-switched inductor multiplier is proposed in this paper. In comparison with other conventional and high step-up DC-DC converters, the proposed converter topology provides higher voltage gain and lower switch voltage stresses for the duty cycles in the range of 0.6 or higher, which is the common duty cycle range of high step-up DC-DC converters. The proposed converter consists of a novel combination of switched capacitors and switched inductors methods which lead to the reduced number of required switches and their duty cycles. The theoretical analysis is confirmed by simulation results in MATLAB/Simulink software environment results. A 100 W laboratory prototype of the proposed converter is implemented to investigate and validate the analytical and simulation results. The prototype DC-DC converter is designed and implemented to be used for a commercial 100 W PEM fuel cell stack power system.

This paper proposes a high step‐up DC–DC converter using coupled inductor voltage multiplier cell and differential connection method. The proposed converter is obtained by differentially connecting a Cuk converter and a Buck‐Boost converter and integrating a coupled inductor voltage multiplier cell. The control mode of the two switches adopts interleaved control and the proposed converter has higher voltage gain. The diode‐capacitor branch in the shared topology is used as a passive clamping branch to reduce the maximum voltage stress of switches. The working principle of the proposed converter is analyzed and its performance parameters and boundary conditions are given. The voltage gain of the converter can be improved by adding different voltage doubling structures and the general topology of the proposed converter is given. The effect of leakage inductance on the performance of the proposed converter is analyzed. Finally, a 300‐W prototype was built and verified the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper introduces a new high step‐up multi‐input multi‐output (MIMO) DC–DC converter control‐based pole placement suitable for photovoltaic system applications. The suggested topology has a high stability current control. Low element number, high voltage conversion ratio, and low ripple input current are the main advantages of the proposed converter. The capability to use several energy resources with different voltage/current characteristics, increase the number of inputs and outputs arbitrary without duty‐cycle limitation, and control each input unit power switch independently are other advantages. The operation principle of the suggested topology, steady‐state analysis in continuous condition mode (CCM), and parameter design are analyzed. A comparison between the suggested topology and other converters is applied. Two‐input two‐output version of the suggested topology in 200 W at an operating 50 kHz switching frequency is analyzed. Finally, the Typhoon HiL‐404 emulating setup is applied to verify the performance and efficiency of the suggested high‐step‐up MIMO DC–DC power converter. [ABSTRACT FROM AUTHOR]

This article proposes a unidirectional high step-up dc–dc converter. The study approaches principle of operation, analysis, guide design, and experimental validation. The high-voltage gain is reached using coupled inductors and voltage multiplier cells (VMC). An interleaved structure of two phases is employed to provide a low-current ripple in the input side. The current balance between the phases occurs due to the insertion of a built-in transformer, which also contributes to increasing the voltage gain. The energy from the leakage inductances is reused, reducing voltage spikes across the semiconductors. Additionally, the proposed converter provides an input–output common ground, which is a requirement for many applications. To verify the proposed converter, a 1-kW prototype, 48–800 V, and 16.67 of voltage gain, was designed and tested. The maximum peak efficiency reached was 94.89% and the rated power efficiency was 93.86%. [ABSTRACT FROM AUTHOR]

This work proposes a novel topology of two‐output high voltage rate DC‐DC converter based on coupled inductor and voltage multiplier cells (VMCs) techniques for renewable energy usages like photovoltaic (PV) systems. The proposed structure has two independent output ports with two voltage gains (M1 and M2). Low voltage stress across the power switch and diodes, common ground between input and output ports, high efficiency, and reduced number of elements are the advantages of the suggested converter. The used diodes are switched at zero current switching (ZCS) and zero voltage switching (ZVS) conditions, which reduce the losses of diodes and subsequently increase the power efficiency. Due to the usage of the coupled inductor, there is no need to a high value of the power switch's duty cycle. Therefore, a low conduction loss and higher efficiency can be obtained. On the other hand, because of the reduced voltage stresses, low rated semiconductors can be used for operation of the presented converter, which decrease the cost and the volume. To demonstrate the performance and effectiveness of the proposed topology, operation principles, steady‐state and efficiency analysis, and also the comparison assessment are provided. Finally, a 200 W experimental development with 50 kHz operation frequency, 20 V input voltage, and 200 and 100 V loads voltages has been implemented in the lab to prove the mathematical surveys. [ABSTRACT FROM AUTHOR]

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In this paper, a high step-up three-level DC–DC converter with a symmetric structure for PV application is proposed. The converter has high voltage gain. This is achieved due to the use of two high step-up cells and two resonant paths in its structure. The converter has low input current ripples and the voltage stress across all switches is equal to half of the output voltage. The proposed converter uses simple pulse–width modulation (PWM) to trigger the switches. Hence, the proposed converter benefits from a simple structure and control circuit. All semiconductor devices are turned on/off under ZCS conditions. Thus, the switching losses are decreased, and the total efficiency is increased. The converter is implemented and tested through a laboratory prototype. The experimental results verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

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 mosfet 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 mosfet 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. [ABSTRACT FROM AUTHOR]

This paper presents a nonisolated high step‐up soft switching DC/DC converter with continuous input and output energy, low input current ripple, and low voltage stress of semiconductors. In this topology, passive clamping circuits are used not only to recycle leakage energy but also to successfully alleviate voltage spikes on the active MOSFET. The leakage inductor, on the other hand, solves the output diode's reverse recovery problem effectively. Furthermore, output capacitors are connected in series to supply the output load, resulting in a smaller output capacitor volume. The suggested topology's operational theory, as well as steady‐state analyses, is thoroughly explored. The proposed topology's voltage gain and switch stress are then compared with that of some high‐gain topologies. After this, a prototype circuit with a 20 V input voltage, 340 V output voltage, and 200 W output power is designed to test the proposed topology's accuracy. [ABSTRACT FROM AUTHOR]

This work proposes a high step-up interleaved dc/dc topology utilizing a VM (voltage multiplier) cell suitable for PV applications. The VM cells D/C (Diode/Cap.) are cascaded among the phases to approach a high voltage gain. Besides, the voltage converting ratio of the presented structure can be improved by extending the VM cells and it also leads to drop in the normalized voltage stress throughout the switches and some diodes. Therefore, by utilizing a semiconductor (Switch/Diode) with a lower rating leads to a decline in system losses. Also, the efficiency of the suggested topology will be considerable and the overall cost can be decreased. To elaborate on the main benefits of the proposed topology, a comparison has been made across other literature regarding the efficiency, peak voltage throughout the semiconductors and voltage ratio of the converter. To prove the accuracy principle of operation of the suggested converter, two prototypes (for n=1, 2 stages) were built and tested at 350 W and 453 W with an operating frequency of about 40 kHz performed. [ABSTRACT FROM AUTHOR]

In this paper, a couple inductor‐based dc‐dc boost converter with extensible capability is presented. In the proposed converter, attaching extensions to input section alleviates input current ripple. Furthermore, the current sharing performance between different phases operates beneficially by expanding optimized boost converters, especially when a partial inequality exists among different switches' duty cycles and leakage inductances. The voltage conversion ratio of the proposed converter is also additionally optimized by a series of VMR's output capacitors. Meanwhile, not only the voltage stress upon the main switches is decreased but also the all switches are managed to be turned on with zero current switching technique. The voltage spikes across MOSFETs are eliminated by using the recycling energy of leakage inductances on the clamp capacitor. The topology of the proposed converter, steady‐state analysis, and design procedure is presented to indicate the merits of the suggested converter. A prototype circuit with a three‐phase interleaved boost converter, two number of diode‐capacitor in each VMR, and output power 660 W and 40–800 V conversion ratio is experimented to corroborate the validity of the presented structure. [ABSTRACT FROM AUTHOR]

High step‐up DC‐DC converters are commonly used in new energy applications such as DC microgrid, photovoltaic cell, and fuel cell. Thus, this article introduces a new nonisolated high step‐up DC‐DC converter based on active switched coupled inductor with a voltage multiplier cell. The proposed converter presents low current and voltage stress across the switches owing of the dual active switches structure. Besides that, by the voltage multiplier cell (one diode and one capacitor), the voltage gain of proposed converter is increased. In addition, it can be highlighted that the proposed converter has low component count, simplicity of operation in continuous and discontinuous conduction mode, and energy stored in the leakage inductor that is recycled in the capacitor of voltage multiplier cell. This article discussed the principle of operation, the ideal and nonideal voltage gain, external characteristic, voltage and current stress, design guidelines, and performance comparison with previous high step‐up converters. Finally, a prototype circuit with input power 300 W, input voltage 30 V, and output voltage 400 V was built in the laboratory to verify the theoretical evaluation, and the maximum achieved efficiency was 95.35% at nominal power 300 W. [ABSTRACT FROM AUTHOR]

In this article, a new high step-up transformerless dc–dc converter based on a voltage multiplier and a coupled inductor topology is presented. The proposed converter has two stages. In the first stage, a modified boost converter is designed by the coupled inductor, and in the second stage, a new voltage multiplier by using a coupled inductor is illustrated. In this converter, high voltage gain can be achieved by adjusting the turn ratio of two coupled inductors and the duty cycle, which result in three degrees of design freedom. Using a single power switch with low on-resistance in the converter structure leads to simple control and low conduction loss. In addition, total voltage stresses of active elements are decreased, which increases efficiency. Steady-state performance and theoretical achievements are confirmed by experimental test results on a test setup with one 200-W dc–dc prototype. [ABSTRACT FROM AUTHOR]

High step-up, high efficiency, low cost DC/DC converters have operated as an interface to make use of the renewable energy system generated power. In order to obtain desired output voltage, the DC/AC voltage conversion to AC mains voltage is an important consideration mainly achieved through inverters. Taking into acoount the performance of the non-isolated high step-up DC/DC converters for the renewable energy systems, the substantial amount of topologies studied in past years are the non-isolated high step-up DC/DC converters. Based on proposed and generalized configurations, the non-isolated high step-up DC/DC converters are classified into several categories and reviewed in this paper. So, to clarify the distinguishing solutions, the key features; topological variations, merits and demerits of these converters are discussed and compared. This review work aims to give a well-informed and a well-detailed general framework about these converters and facilitates to derive the new well topologies in the future.

A new interleaved high step-up converter with Zero Voltage Transition (ZVT) is proposed for operation in this paper. The main advantages of the proposed converter are low input current ripple and low voltage stress on the power switches, high efficiency, low total component count, and eliminating reverse recovery problem of power diodes. Due to the soft switching operation of the switches and diodes in the converter, the efficiency has been enhanced. Also, the switches do not have capacitive turn on loss due to ZVT operation. The proposed converter uses only one power switch to provide ZVT conditions for all switches and the clamp capacitor transfers its energy to the lifting capacitor, which causes increase in voltage gain of the converter. Because of the interleaved structure, the converter has a low input ripple current and this advantage makes it very suitable for solar applications. The proposed converter is analysed and a 580W prototype is made to verify theoretical analyses.

This paper proposes an interleaved high step-up DC-DC converter with the coupled inductor (CI) and built-in transformer (BIT) for renewable energy applications. Two double-winding (2W) CIs and one triple-winding (3W) BIT are integrated with the switched-capacitor (SC) voltage multiplier cells (VMCs) to achieve high-voltage gains without extreme duty cycles. The CIs and BIT turns-ratios provide two other degrees of freedom—in addition to the duty cycle—to adjust the voltage gain that leads to increased design flexibility. The diodes turn off naturally under the zero-current switching (ZCS) conditions because their current falling rates are controlled by the leakage inductances of the CIs and BIT; therefore, the diodes’ reverse-recovery problems are alleviated. Moreover, employing passive diode-capacitor clamp circuits, the voltage stresses of the switches are limited to a low value far less than the output voltage. Additionally, the leakage inductances energies are recycled and transferred to the output to further extend the voltage gain. Furthermore, due to the interleaved structure, the input current ripple and current stresses of the components are reduced. The proposed converter is analyzed in detail and then compared with similar converters that employed CIs and/or BIT along with passive/active clamp circuits for the MOSFETs. Finally, to verify the feasibility of the proposed converter, the experimental results of a 200 W prototype with output voltage of 400 V and voltage gain of 25 are presented.

This paper proposes a high voltage step-up DC/DC converter by combining a coupled inductor and a voltage multiplier rectifier. The input side of the proposed converter operates in an interleaved manner with two coupled inductors connected in parallel, and the output side is composed of a voltage multiplier rectifier where two voltage doubler rectifiers are merged in series. By changing the turns ratio of the coupled inductor of the proposed converter, the voltage gain can be increased, and additional voltage gain can be obtained by combining it with a voltage multiplier rectifier. Due to the passive lossless clamping performance of the proposed method, it is possible to recycle the leakage inductance energy of the coupled inductor and voltage stress reduction can be achieved along with zero current turn–ON and turn–OFF of switches and diodes. Finally, this paper evaluates the effectiveness and practicality of the proposed method by operating a prototype circuit with an input voltage of 20V, an output voltage of 400V, and an output power of 320W. The maximum efficiency of the proposed converter is 97.2% and the efficiency at maximum power is 94.1%.

This paper introduces a high-step-up dc-dc converter to provide voltage boosting in low-voltage applications. The circuit contains only a single active switch and is based on the boost-type converter using coupled inductor and voltage multiplier cell. The proposed topology exhibits high efficiency, reduced voltage stress on the semiconductors and requires a low component count. The circuit is intended for applications with rated power in the order of a few hundreds of Watts, which corresponds to the typical level of a single photovoltaic (PV) module. A detailed mathematical description of the circuit operation is carried out, providing the means for the adequate design of the converter. The dynamic analysis is also addressed in the paper, and proper closed-loop operation is demonstrated. A 400 W prototype operating at 90 kHz, with an input voltage range of 24–48 V and output voltage of 400 V was built and tested in laboratory. Experimental results validate the analyses carried out and measurements indicate efficiency levels up to 97.5%, which ratifies the proposed converter as a good solution for typical PV applications.

A high step-up PWM non-isolated dc–dc converter with soft switching is proposed in this paper. The converter has minimum auxiliary elements to achieve high power density and high voltage gain. The ZVS operation of the main power switch results in negligible capacitive turn-on losses. Since the duty cycle of the auxiliary switch is narrow and its operation is under ZCS condition, the losses that the auxiliary circuit imposes are not significant. Also, all the diodes are operated under soft-switching conditions solving the reverse recovery problem. All the inductors are coupled on only one magnetic core, reducing size and conduction losses. Compared to the hard switched counterpart, the electromagnetic interference of the proposed converter is reduced. Furthermore, the output voltage of the proposed converter is controlled by an integral sliding mode control strategy during the load variations. Also, the proposed integral sliding mode control strategy has been compared with the PI control strategy, improving the transient response and the robustness under load variations while the switching frequency is constant. The effectiveness and accuracy of the proposed converter are verified by practical laboratory results which are obtained from a 250W prototype.

In this paper, a Multi-Input Multi-Output (MIMO) high step-up transformerless DC-DC converter is proposed. The proposed converter can expand the number of ports from both input and output terminals. Also, it has a modular structure using voltage multiplier cells (a switch, two diodes, a capacitor, and an inductor). The proposed converter is useful for a wide range of applications and has the merit of interfacing multiple hybrid voltage sources with each other to supply different loads with various voltage levels. All the output voltages of the output ports can be regulated at the same time by tuning separate controlling parameters. Since digital control has the benefit of (1) enhancing efficiency, (2) higher flexibility than analog electronics, (3) ease of use, (4) improving reliability and stability in hybrid energy conversion applications, this method of controlling implementation is adopted. The key contributions of this article would be 1) expandable modular MIMO converter with high performance for all range of duty cycles; 2) integration of hybrid energy sources and delivering to multiple loads; 3) nonlinear digital controlling approach to achieve fast transient response under the variation of input voltage sources and output loads, and 4) high voltage gain with low normalized power stress on switches. To simplify the analysis, first, single-input, dual-output (SIDO) mother-module, dual-input, three-output (DITO) and three-input, four-output (TIFO) developed modules are carefully analyzed and then, the MIMO structure is explained. To verify the theoretical results, a prototype of SIDO operation of the proposed converter with a digital controlling scheme is implemented for 30V input voltage /150V, 250V output voltages with the total power of 450W. Furthermore, experimental results of DITO operation with 30V and 40V input voltages/150V, 250V, 405V output voltages with the total power of 800W are extracted.

Summary: In this article, a high step‐up interleaved boost converter topology is proposed for renewable energy applications. The proposed converter utilizes two‐phase interleaved configuration, to increase the power capability of converter while reducing the input current ripples. The output side formation enhances the voltage gain with the help of coupled inductors. It produces high voltage conversion ratio with least voltage stress on the switches. The switches are relieved from the voltage spikes by reclaim the energy leakage of the coupled inductors, which minimizes reverse recovery problem in diodes. The conduction losses of the switches are reduced due to small on state resistance. Finally, a prototype of 200 W proposed converter is developed in the laboratory to verify the both theoretical analysis and simulation results. [ABSTRACT FROM AUTHOR]

This work presents a nonisolated high step‐up single‐ended primary inductance converter (SEPIC) topology for high‐power, high‐current applications. The converter operation is based on the interleaving principle, and the active switches are driven by gating signals phase shifted by 180°, whereas automatic current sharing is achieved owing to an autotransformer with unity turns ratio. It is possible to extend the voltage gain employing voltage multiplier cells (VMCs) composed of diodes and capacitors. Prominent advantages of the structure include low current and voltage stresses on the semiconductors, inherent modularity, better thermal distribution, and reduced dimensions of the filter elements. A comprehensive theoretical analysis is derived, from which a 1‐kW prototype is designed and thoroughly evaluated. [ABSTRACT FROM AUTHOR]

In this article, a new triple-switch triple-mode (TS-TM) high step-up dc–dc converter is proposed. The proposed converter consists of three switches, four diodes, two magnetically coupled inductors, and three capacitors. This converter can provide a high voltage conversion ratio with high power efficiency and low voltage stress across the power semiconductor components. Due to the low voltage stresses of the power semiconductors and implementing the coupled inductors technique, the proposed converter is a low-cost and high-efficient structure in comparison to the other similar TS-TM structures. In order to clarify the advantages of the proposed converter, the required mathematical calculations and comparison results with similar converters are presented. Also, a novel TS-TM with transformer is proposed to overcome the electromagnetic interface problems. Furthermore, a 500 W experimental prototype is built and its performance with different values of duty cycles is tested to prove the claimed features of the proposed converter. A total of 94.5% maximum power efficiency of the assembled prototype has been obtained at 260 W output power. [ABSTRACT FROM AUTHOR]

This paper presents a new technique to mitigate the high voltage stress on the secondary gallium nitride (GaN) transistor in a high step-up flyback application. GaN devices provide a means of achieving high efficiency at hundreds (and thousands) of kHz of switching frequency. Presently however, commercially available GaN is limited to only a 650 V absolute voltage rating. Such a limitation is challenging in high step-up flyback applications due to the secondary leakage. The leakage imposes high voltage stress on the secondary GaN rectifier during its turn-off transient. Such stress may cause irreversible damage to the GaN device. A new method of leakage bypass is presented to mitigate the high voltage stress issue. The experimental results suggest that when compared to conventional secondary active clamp, a 2.3-fold reduction in overshoot voltage stress percentage is achievable with the technique. As a result, it is possible to utilize GaN as the rectifier while keeping the peak voltage stress within the 650 V limitation with the technique. [ABSTRACT FROM AUTHOR]

Increased high-power exigency in industries insists for high step-up converters. Boost topology of DC–DC converters is the simplest and most used structure in numerous applications. This paper proposes a non-isolating type novel cluster switched inductor Boost (CSIB) hybrid converter having elevated voltage adaptation ratio. The key attribute of the projected CSIB converter is it gives high gain ratio when compared to other Boost topologies. With the same equivalent inductance value (while transferring energy to the load) as that of conventional converters, the proposed CSIB converter furnishes high voltage conversion ratio and adds an additional feature of proposed CSIB Hybrid DC–DC converter. With high conduction losses at high duty ratio and high parasitic resistance, distributed inductor shows a prominent role in increasing the gain of the converter and is the case in proposed CSIB converter. Transformer-less operation of novel CSIB converter reduces the size and avoids EMI/EMC effects, which is an added advantage. The Novel Cluster Switched Inductor Boost (CSIB) hybrid DC–DC converter in CCM operation is compared with Hybrid Boost and Symmetrical Hybrid Switched Inductor converter (SH-SLC) topologies to validate its performance. Simulation analysis is presented using MATLAB/SIMULINK software. [ABSTRACT FROM AUTHOR]

This article presents a precise derivation of the prevalent voltage-drop problem in pulsewidth modulation high step-up converters with a transformer-based voltage multiplier. The corresponding solution is proposed and analyzed with an isolated interleaved full-bridge high step-up converter as an example. By introducing a resonant capacitor, the improved converter solves the voltage-drop problem caused by the reverse recovery process of the leakage inductor. Meanwhile, the zero-current switching condition is achieved for output diodes due to the resonance between the leakage inductor and the resonant capacitor. Moreover, the proposed solution can be extended to other high step-up converters with voltage-multipliers utilizing transformers or coupled inductors. The voltage-drop problem is analyzed in detail first, followed by the operational principles and steady-state analysis of the improved converter. Experimental results based on a 450-W laboratory prototype at 25-kHz switching frequency verify the validity of the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper presents a non‐isolated high step‐up buck–boost with a coupled inductor DC–DC converter relevant for distributed photovoltaic (PV) generation systems. The proposed topology can reach high voltage gain through the combination of a buck–boost converter with a coupled inductor. The configuration of the proposed converter allows to achieve a natural voltage clamp circuit for the switch, recovering the energy stored in the leakage inductance of the coupled inductor. Moreover, the converter allows soft‐switching conditions, that is, Zero Current Switching (ZCS) for the diodes and nearly ZCS for the active switch. Also, the proposed converter presents a low component count and common ground connection of the input and output. The proposed converter is evaluated theoretically by the principle of operation in continuous‐conduction mode (CCM) and discontinuous‐conduction mode (DCM), voltage gain derivation, external characteristics, semiconductor voltage stress, current stress, and design guidelines. Finally, a 650‐W, 36/380‐V, 50‐kHz prototype was built in the laboratory to experimentally evaluate the proposed converter, which reached a maximum efficiency rate of 96.58%. [ABSTRACT FROM AUTHOR]

In this paper, a new non-isolated DC-DC converter is proposed. This converter topology is a high step-up boost converter with an extended voltage multiplier cell and a Cuk converter as a series output module. Compared to its high step-up counterpart, the proposed converter has a higher voltage gain. In this converter, an active clamp circuit is used to absorb the energy of leakage inductor, therefore, the ZVS turn on/off for switches and ZCS for diodes are achieved. The voltage stresses on the switches are low, and the reverse-recovery problem of the diodes is eliminated. The operational principle and characteristics of the proposed converter are presented. The analytical and simulated results are validated using a 200 W prototype converter with 20 V input and 400 V output operating at 100 kH. [ABSTRACT FROM AUTHOR]

In order to solve the shortcoming that Boost converter can obtain high voltage gain under the limit duty cycle, a new type of high-gain converter is proposed on the basis of the traditional Sepic converter. The converter retains the advantages of the continuous input current of the Sepic converter, by introducing a passive clamp circuit, the voltage stress of the switch tube is reduced, at the same time, the leakage inductance and the capacitor in the circuit have a resonance process, effectively reducing the impact of the diode reverse recovery problem. The working process of the converter in each switching mode was analyzed in detail, the voltage gain expression of the converter was deduced, and the voltage stress of the switching device were calculated. A 100 W experimental prototype was made, and the correctness of the theoretical analysis is verified through experiments.

An interleaved zero-voltage zero-current switching (ZVZCS) high step-up DC-DC converter is proposed for modern photovoltaic power generation systems. The proposed converter can achieve high voltage conversion gain without operating under extreme duty cycles. The voltage conversion gain can be readily adjusted by selecting different numbers of the diode-capacitor multiplier (DCM) cells in the circuit at the design stage. Moreover, with the passive snubber circuit in the proposed converter, all power switches and diodes in the DCMs can achieve zero-voltage turn-off and zero-current turn-on, which effectively reduces switching losses and increases the overall converter efficiency. The operational principles and analysis of the performance analysis with two DCMs are presented for demonstrative purpose. The effectiveness of the proposed ZVZCS DC-DC converter is validated using an 800W experimental prototype.