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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.

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.

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. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University.

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.

In this paper, a fuel-cell (FC)/battery hybrid direct-current (DC) backup power system is proposed for high step-up applications. This system is composed of a newly developed non-isolated three-port converter, which achieves a high voltage gain by taking the advantage of a quasi Z-source network and an energy transfer capacitor. After analyzing the converter, a comprehensive comparison study and a design procedure are provided. Moreover, the controllers regulating the source power levels while smoothing the FC power profile according to the proposed energy management strategy (EMS) are designed based on the developed small-signal model of the proposed converter. Both hardware and controller design procedures are validated through the PSIM model of the whole system. As a result, it is shown that the proposed system can effectively couple FC and battery while transferring their energies to a high voltage DC bus according to the offered EMS. (c) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. WOS:000706634600004 2-s2.0-85118133245

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.

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.

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.

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.

A new high step-up DC-DC converter for renewable energy applications is proposed in this paper. Employing an interleaved quadratic structure, two two-winding coupled inductors (CIs), and voltage multiplier cells (VMCs), the proposed converter can provide high-voltage gains, continuous input current with low ripple, reduced voltage stresses on semiconductors, common ground between input and output sides, and low numbers of components. In addition, diode-capacitor lossless clamp circuits are utilized to limit the voltage stresses of the power switches and further extend the voltage gain. The operating and steady-state analyses, design considerations, and a comparison with other previously published high step-up converters are presented. Lastly, experimental results of a 400 W prototype with 400 V output voltage are illustrated to verify the theoretical analysis and the functionality of the proposed converter.

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.

In significant cases, the generated voltage needs to be step-up with high conversion ratio by using the DC-DC converter as per the requirement of the load. The drawbacks of traditional boost converter are it required high rating semiconductor devices and have high input current ripple, low efficiency, and reverse recovery voltage of the diodes. Recently, the family of Multilevel Boost Converter suggested and suitable configuration to overcome the above drawbacks. In this article, hybrid DC-DC non-isolated and non-inverting Nx Interleaved Multilevel Boost Converter (Nx-IMBC) is analyzed in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) with boundary condition and investigated in detail. The Nx-IMBC circuit combined the features of traditional Interleaved Boost Converter (IBC) and Nx Multilevel Boost Converter (Nx-MBC). The modes of operation, design of Nx-IMBC and the effect of the internal resistance of components are presented. The comparison study with various recent DC-DC converters is presented. The experimental and simulation results are presented with or without perturbation in input voltage, output power and output reference voltage which validates the design, feasibility, and working of the converter.

In this paper, a high-efficiency DC/DC converter with low voltage stress is designed for green power applications. The proposed non-isolated high step-up DC/DC converter combines the advantages of switched capacitors, coupling inductors, and voltage multiplier techniques. Adding the cells of the switched capacitor not only increases the voltage gain but reduces the voltage stress of the semiconductor devices. High voltage gain can be achieved by adding a coupled inductor method to adjust the turns ratio. When these are combined with a voltage multiplier circuit, the leakage energy of the coupled inductor is recirculated to the output terminal with lossless passive clamping performance. The leakage inductance of the coupled inductor controls the current dropping rate of the output diode turn OFF so that the reverse-recovery problem is mitigated. The proposed converter integrates these three techniques to achieve high voltage gain without operating at maximum duty cycle. In addition, switching loss reduction is realized through zero current switching turn ON soft switching performance with low voltage stress of semiconductor devices. Finally, this paper verifies the performance of the proposed converter for theoretical analysis by using a $35\sim 45\text{V}$ input, 380V output, and 1kW power prototype circuit.

In this article, a quasi-switched boost converter based on the switched-capacitor technique with high step-up voltage capability is dealt with and analyzed. The proposed converter offers a simple structure and low voltage stress on the semiconductor elements with intrinsic small duty cycle. An inductor of the proposed converter is connected in series with the input voltage source; therefore, continuous input current ripple is attainable. In addition, the efficiency of the proposed converter is also improved. A detailed steady-state analysis is discussed to identify the salient features of the switched-capacitor-based quasi-switched boost DC-DC converter. The performance of the converter is compared against similar existing high boost DC-DC converters. Finally, the switched-capacitor-based quasi-switched boost DC-DC converter is investigated by experimental verification.

Recently, an extended-duty-ratio (EDR) boost converter has attracted great attention of many scholars. However, the EDR boost converter with fix phase shifts is difficult to achieve phase-to-phase current sharing over a wide range of duty ratio. In this article, a variable phase-shift control strategy is proposed to further expand its current sharing range for the EDR boost converter. Under the proposed control strategy, the EDR boost converter can operate in wide range of duty ratio varying from 0.5 to 1 with automatic current sharing between phases since two adjacent phase shifts can be adjusted to guarantee that the energy stored in certain inductor is only transferred to the next phase capacitor step by step for generating high step-up output voltage. Next, the steady-state analysis of the EDR boost converter under the proposed control strategy is discussed thoroughly, and the switch voltage stresses and current stresses are also analyzed. Finally, a 300 W, 3.3 V to 38.9 V, four-phase EDR boost hardware prototype has been built. The effectiveness of the proposed control strategy is verified by the experimental results of the built prototype.

This paper presents an analysis on the effect of a parasitic capacitance full-bridge class-D current source rectifier (FB-CDCSR) on a high step-up push–pull multiresonant converter (HSPPMRC). The proposed converter can provide high voltage for a 12 VDC battery using an isolated transformer and an FB-CDCSR. The main switches of the push–pull and diode full-bridge rectifier can be operated under a zero-current switching condition (ZCS). The advantages of this technique are that it uses a leakage inductance to achieve the ZCS for the power switch, and the leakage inductance and parasitic junction capacitance are used to design the secondary side of the resonant circuit. A prototype HSPPMRC was built and operated at 200 kHz fixed switching frequency, 340 VDC output voltage, and 250 W output power. In addition, the efficiency is equal to 96% at maximum load. Analysis of the effect of the parasitic junction capacitance on the full-bridge rectifier indicates that it has a significant impact on the operating point of the resonant tank and voltage. The proposed circuit design was verified via experimental results, which were found to be in agreement with the theoretical analysis.

This study mainly develops a high-efficiency single-input triple-outputs dc/dc converter (HSTDC) with a soft-switching technique for high step-up applications. In general, multiple output voltages with only one single input power source is always required for the applications of renewable energy or electric vehicles. At the high step-up operation, the proposed HSTDC has a high voltage conversion ratio to sustain the high-voltage dc bus for the utilization of dc/ac inverter. The proposed HSTDC uses a coupled inductor with lower turn ratios to achieve the high step-up voltage gain and adopts an auxiliary inductor to adjust the voltage of the auxiliary output terminal indirectly. Moreover, the utilization of voltage clamping and zero-current switching (ZCS) in the proposed HSTDC is helpful for accomplishing the goal of high-efficiency power conversion and three output voltage levels. In addition, the effectiveness of the proposed HSTDC is verified by rich experimental results.

The widely utilization of renewable energy with low output voltage makes the high voltage ratio boosting converter more popular. This article introduces a non-isolated low input ripple high step-up extendable hybrid DC-DC converter. The proposed converter is based on a two-phase interleaved BOOST converter and switch-capacitor (SC) boost circuit. One of the BOOST channels charges the capacitors in the SC circuit, and the other BOOST channel is connected in series with the capacitors to supply power to the load. Benefiting from this structure, the converter achieves high voltage gain, reduced semiconductor voltage stress, and low input current ripple. Moreover, the converter can be extended by increasing the number of switch-capacitor boost units or the parallel BOOST channels to perform better in voltage gain, input current ripple, and power density. The principle of operation, theoretical analysis, expansion scheme, and comparison with similar topologies are introduced in detail. Finally, a 100W prototype is implemented to verify the validity of the theoretical analysis.

This paper proposes a high step-up low-ripple dc-dc converter for sustainable energy conversion. A high step-up voltage gain is obtained with an input-current doubler and a switched-capacitor circuit rather than having to use a transformer with a high turn ratio. A low input current ripple is achieved since the current ripples of two input inductors cancel each other out when the primary-side branches work in an interleaving way. A low output voltage ripple is got by charging and discharging complementarily with each other of two output capacitors. In addition, the proposed converter achieves zero-voltage switching (ZVS) for all power switches and zero-current switching (ZCS) for all rectifier diodes, which reduces the switching loss significantly. Moreover, an active-clamp capacitor is installed on the input-current doubler to suppress the voltage spike across the switches. A 400-W prototype converter was realized to demonstrate the above-mentioned performance.

An interleaved high-step-up current sharing DC–DC converter with coupled inductors is proposed in this paper. The operation principle and property of this converter are analyzed. The ripple of the input current in the proposed converter is decreased significantly by using the two-phase parallel interleaved input. The voltage gain is extended and the switch voltage stress is reduced by the coupled inductors. The leakage inductance of the coupled inductors reduces the reverse-recovery problem of the output diode, resulting in the reduction of reverse-recovery losses. As there are two interleaved phases in the proposed converter, the third winding of each coupled inductor is embedded in another phase. With this design, when the leakage inductance or duty cycle is asymmetrical, the current sharing performance is still positive. Consequently, the new topology is very suitable for applications to occasions with low voltage input and high voltage output, such as the fuel cell power system. Finally, the performance of this topological circuit is verified by a prototype with 500 W output.

In significant cases, the generated voltage needs to be step-up with high conversion ratio by using the DC-DC converter as per the requirement of the load. The drawbacks of traditional boost converter are it required high rating semiconductor devices and have high input current ripple, low efficiency, and reverse recovery voltage of the diodes. Recently, the family of Multilevel Boost Converter suggested and suitable configuration to overcome the above drawbacks. In this article, hybrid DC-DC non-isolated and non-inverting Nx Interleaved Multilevel Boost Converter (Nx-IMBC) is analyzed in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) with boundary condition and investigated in detail. The Nx-IMBC circuit combined the features of traditional Interleaved Boost Converter (IBC) and Nx Multilevel Boost Converter (Nx-MBC). The modes of operation, design of Nx-IMBC and the effect of the internal resistance of components are presented. The comparison study with various recent DC-DC converters is presented. The experimental and simulation results are presented with or without perturbation in input voltage, output power and output reference voltage which validates the design, feasibility, and working of the converter.

Step-up DC-DC converters play a determinative role in traction vehicles by providing the required DC- link voltage for traction drives supplied by battery packages or fuel cells. Bi-directional converters are preferred to be used in the construction of battery-based traction drives to charge batteries when drivetrains system work in the generation mode. However, due to the fact that fuel-cells cannot be charged electrically, the bi-directional structure is not required for fuel cell-based traction drives. The proposed step up converter benefits from the resonance between its elements to provide the soft- switching condition for the converter switches. The resonance assists to transmit high power from input and to output while there is no high-frequency transformer or coupled inductor in the converter topology. In brief, the generated resonance not only leads to a high power density converter but also result in a soft-switching which means higher efficiency in comparison to previously introduced high-step up converters working in hard switching condition. So, the proposed high-efficiency high power density high step-up (HHH) converter could be employed as a reliable DC-DC converter for traction vehicles supplied by fuel cells. Refereed/Peer-reviewed

In this paper, a new, high step-up quadratic boost converter with high conversion efficiency is discussed. A storage capacitor and resonant inductor are connected in series with a clamp capacitor through a diode. These compose a voltage multiplier cell, which is applied on the switch of the quadratic boost converter. The clamp capacitor can protect the switch from a voltage spike and absorb energy when the switch turns off; then, the storage capacitor and resonant inductor are charged by the energy stored in the clamped capacitor to increase the voltage transfer gain. In addition, the voltage multiplier cell can also reduce the voltage stresses of power devices. Then, a 16 V input, 200 V output prototype with 80 W nominal power is built up and tested. Furthermore, a finite time fast terminal sliding mode (NFTSM) control is proposed, with constant frequency for the voltageFundamental Building B213:tracking control of this converter. The new NFTSM is obtained by introducing an adjustable nonlinear term into fast terminal sliding mode (FTSM) control, and a singularity problem is avoided. The experiment illustrates that the maximum efficiency of the proposed converter achieves 95% at D = 0.25 , V o = 150 V. The voltage stress is reduced to half of the corresponding component of the basic boost converter at the same voltage level. Moreover, the proposed NFTSM controller can track the reference signal, and provide a short settling time of about 48 ms with no overshoot, and the system response exhibits strong robustness against 11.7% input voltage disturbance and 30% load variation.

This paper proposes new zero current switching (ZCS) transformerless high gain DC-DC converters for renewable energy conversion systems. A conventional high gain transformerless DC-DC converters derived with a simple auxiliary resonant network to obtain zero current switching (ZCS) turn-off condition of the main switches. The proposed converter is operated to achieve high step-up and soft-switching operations in order to have minimized current stresses and reduced switching losses, since the high duty ratios to the main switches does not affect the overall performance of this converter. The advantages of this converter are minimized turn-off losses and duty ratio is not limited. The proposed converter improves the overall efficiency over hard-switching converter for high voltage energy conversion system applications. In this paper a new ZCS high gain DC-DC converter is presented, analyzed in detail to demonstrate the operation principles and verified by the simulation results.

We propose a high step-up resonant dc–dc converter that can achieve voltage balance of the resonant capacitors in distributed generation systems. By incorporating a switching mechanism on the secondary side, we achieve high step-up voltage gain with a minimum number of devices and without reverse-recovery problem. An active-clamp circuit installed on the primary side suppresses the surge voltage that occurs at switch components, recycles the energy stored in the leakage inductance, and provides an alternate resonant-current path formed by the leakage inductance and the output resonant capacitors. A dual resonance that occurs at the secondary side of the converter is exploited to reduce the turn- off current and switching loss significantly, and to achieve high power conversion efficiency. The resonant capacitor voltages remain in balance because the duty cycle of the primary-side switches is always set to 0.5, regardless of the input voltages and load variations. Design and analysis of the proposed converter are presented, and tests using a 400-W experimental prototype verify its superior performance.

High Step-up converters have numerous applications in renewable energy systems and electric automotive industry. To improve the power density, an interleaved high step-up boost converter with coupled inductor was proposed. However, for practical applications it is compulsory that this topology must comply with the CISPR standards. Therefore, to identify the noise sources in the analyzed converter, an equivalent noise modelling is conducted. These models revealed the dependency of inductor windings on different noise sources. For experimental analysis of the conducted emissions of this topology, GaN FETs based prototype is designed. Several tests were carried out to find the effect of various factors on noise emission. As results of tests, 1) Increasing the switching frequency generates increase in the noise spikes 2) Noise emissions from the converter do depend on its mode of operation 3) High peaks of noise are generated at low frequency range by reducing the voltage transition time across the switch.

This paper proposes and discusses a novel AC/DC converter suitable for small-scaled wind power generation system applications. By introducing flyback cells into the three-phase single-switch Boost circuit, the proposed converter is designed as single-stage and has both rectification and high step-up power conversion functions. It is able to obtain high voltage gain at low input voltage level, and high efficiency, low total harmonic distortion (THD) at rated power. The inherent power factor correction (PFC) is also determined, and can reach 0.99. Besides, since no electrolytic capacitor is employed and high voltage gain is achieved, the converter can also collect weak power at low input voltage in combination with energy storage devices, and contribute to a better low-wind-speed/low-power performance. Finally, a 400 W prototype is built to verify the theoretical analysis, and its efficiency is 87.6%, while THD is 7.4% at rated power.

In this paper, an isolated high step-up single switch DC-DC converter for renewable energy source is proposed. In the proposed converter high step-up voltage is obtained by single power switching technique that operates low duty cycle with isolated transformer inductors and switched capacitors and power diodes. The disadvantage of conventional converters is that it has high duty ratio and high voltage stress on power devices with less efficiency. The proposed converter eliminates the switching losses and recycles the leakage energy which includes reverse recovery energy of the power diode by using passive clamp circuit. To achieve high output voltage gain, the isolated transformer primary terminal and secondary terminal are connected in series during switching operation. PSIM software has been used for simulation. Simulation circuit is analyzed at 40Vdc/400Vdc, 200 W and this operation is validated by implementing in the hardware model at 12Vdc/120Vdc, 60 W.

This article presents a new non-isolated DC-DC sextuple output hybrid triad converter configurations for high step-up renewable energy applications. Total 8 (eight) converters configurations are obtained by combining SEPIC/SI-SEPIC, Cuk/SI-Cuk, and Boost/SI-Boost which is highly suitable for step-up renewable applications where DC-DC multi-output converters/choppers are needed; such as a solar multilevel DC-AC converter (MLI), HVDC, hybrid/electric and electric vehicles. The most important characteristics of the proposed converter configurations are (i) only one power control semiconductor switch, (ii) offer six different DC outputs with different conversion ratio, (iii) non-isolated (without transformers) Converter topologies, (iv) high voltage at the output side without using large duty cycle and (v) modular DC-DC converter structure. The simulation results are presented and it validates the practicability, functionality, and the idea of suggested sextuple output hybrid triad converter configuration.

In this paper interleaving and switched-capacitor techniques are used to introduce a high step-up DC-DC converter for renewable energy systems application. The proposed converter delivers high voltage gain without utilizing transformer or excessive duty cycle and features ripple-free input current which results in lower conduction losses and decreased electromagnetic interference (EMI). Lower output capacitance is another advantage of proposed converter, leading to smaller size and lower cost. Furthermore lower voltage stress on switches allows the utilization of switches with low resistance. Simulation results verify the performance of suggested converter.

There is an increasing trend of development and installation of switching power supplies due to their highly efficient power conversion, fast power control and high quality power conditioning for applications such as renewable energy integration and energy storage management systems. In most of these applications, high voltage conversion ratio is required. However, basic switching converters have limited voltage conversion ratio. There has been much research into development of high gain power converters. While most of the reported topologies focus on high gain and high efficiency, in this thesis, the input and output ripple currents and reliability are also considered to derive a new converter structure suitable for high step-up voltage conversion applications. High ripple currents and voltages at the input and output of dc-dc converters are not desirable because they may affect the operation of the dc source or the load. A number of converters operating in an interleaved manner can reduce these ripples. This thesis proposes a dc/dc switching converter structure which is capable of reducing the ripple problem through interleaved action, in addition to high gain and high efficiency voltage conversion. The thesis analyses the proposed converter structure through a dual buck-boost converter topology. The structure allows different converter topologies and combinations of them for different applications to be configured. The study begins with a motivation and a literature review of dc/dc converters. The new family of high step-up converters is introduced with an interleaved buck-boost as an example, followed by small-signal analysis. Experimental verifications, conclusions and future work are discussed.

The increase of the demand in efficient energy converters is a very promising line of research for small renewable energy generators and systems. It involves a maximum optimization of electronic structures using the most recent dedicated and improved components. A simple and efficient DC/DC converter related to smart grids applications connected to High Voltage Direct Current (HVDC) bus presents many advantages compared to classical distribution system on AC grids. This study is particularly orientated to the distributed energy converters for photovoltaic (mono-, poly-crystalline, amorphous) or wind production. The HVDC bus reduces the energy transport cost and is a protection way against vandalism, but the main advantage of this architecture is related to the possibility of connecting several mismatched generators without disturbing the other ones. In this paper a specific analysis was done on a magnetic coupled inductor boost DC/DC converter in order to determine the coupling factor influence. It is well known that high voltages can be obtained by using a specific transformer or coupled coils. In fact, the coupling factor decreases with the insulation voltage and fabrication constraints. Based on comparisons of simulation results with a discrete analysis, this work analyses the influence of the magnetic coupling coefficient on the coupling coils operations and on the efficiency of the converter. This study which can allow a more useful way to develop new similar DC/DC converter systems.

This dissertation presents the derivation, analysis and application issues of advanced topologies with coupled inductors. The proposed innovative solutions can achieve significant performance improvement compared to the state-of-the-art technology. New applications call for high-efficiency high step-up DC-DC converters. The basic topologies suffer from extreme duty ratios and severe rectifier reverse recovery. Utilizing coupled inductor is a simple solution to avoid extreme duty ratios, but the leakage inductance associated with the coupled inductor induces severe voltage stress and loss. An innovative solution is proposed featuring with efficient leakage energy recovery and alleviated rectifier reverse recovery. Impressive efficiency improvement is achieved with a simple topology structure. The coupled inductor switching cell is identified. Topology variations and evaluations are also addressed. The concept that utilizes coupled inductors to alleviate rectifier reverse recovery is then extended, and new topologies suitable for other applications are generated. The proposed concept is demonstrated to solve the severe rectifier reverse recovery that occurs in continuous current mode (CCM) boost converters. Significant profile reduction and power density improvement can be achieved in front-end CCM power factor correction (PFC) boost converters, which are the overwhelmingly choice for use in telecommunications and server applications. This dissertation also proposes topologies to realize the single-stage parallel PFC by utilizing coupled inductors. Compared to the state-of-the-art single-stage PFC converters, the proposed topologies introduce a new power flow pattern that minimizes the bulk-capacitor voltage stress and the switch current stress. Ph. D.

This paper presents an an alysis and comparison of magnetics structures in a tapped boost converter for LED applications. The magnetic structure is a coupled inductor which is analyzed in a conventional wire-wound core as well as in a planar structure for different interleaving winding arrangements. The analysis is performed in term s of leakage inductance, winding capacitance and winding loss. Efficiency measurements are performed to verify the effect on the converter performance