MODELING, DESIGN, AND IMPLEMENTATION OF HIGH GAIN POWER ELECTRONIC DC-DC CONVERTERS FOR NANOGRID APPLICATIONS

Nanogrids are nothing but power distribution systems that are based on renewable energy sources and are apt for low-power home applications. Nanogrids are considered to be the building cells of a Microgrid. Nanogrid is intended for feeding domestic loads (of the order of 100 W to 5 kW) from renewable energy sources such as wind farms, roof-top solar photovoltaic, biomass, and fuel cell, etc. Nonetheless, the voltages produced by these renewable energy sources are small and not sufficient enough to be utilized in all the applications. Hence, it is necessary to include high gain and high-efficiency DC-DC converters in the system. To interface the generators and the loads, power electronic converters are employed within a Nanogrid. The power system grid is also linked to the Nanogrid using these converters. The most fundamental characteristics of the high-gain DC-DC converters are high efficiency, high-voltage gain, and low voltage/current stress on switching components. A comprehensive literature review of various boosting methods is disseminated in this research work. After a detailed investigation, five new DC-DC power converter topologies have been designed and developed to achieve high gain factors with reduced switch ratings and low cost for use in Nanogrids. The proposed converters cannot only reduce voltage/current stresses across the switching components significantly but also achieve a higher voltage gain at moderate duty cycles with a lesser number of components. Moreover, the proposed converters are designed in such a way that they can maintain a continuous input current, and hence making them useful for power conversion in the battery, fuel cell, and solar PV applications. By using boosting technique five novel high voltage gain DC-DC converters are developed and presented in the dissertation, namely: 1. modified Switched Inductor Boost Converter (mSIBC) with reduced switch voltage stress, 2. Transformer-less Boost Converter (TBC) with reduced voltage stress, 3. Switched-Inductor based DC-DC Converter with reduced switch current stress, 4. Novel High Gain Active Switched Network-Based Converter, and 5. Double Stage Converter with low current stress for Nanogrid The detailed theoretical analysis of the voltage conversion ratio, parameter design, continuous and discontinuous conduction mode, and advantages are presented. In addition, a detailed comparative study of each converter topology is also given. The functionality of the proposed power converters is tested in real-time by developing Laboratory prototypes of the proposed converters and the theoretical analysis is validated by obtaining the experimental results. The proposed converter configurations are simulated in MATLAB as well, to verify the theoretical analysis. Simulation results of all the proposed converters are presented indicating clear evidence of the expected predictions in close proximity with experimental results

Association of depression with sexual function in women with history of recurrent pregnancy Loss:descriptive-correlational study in Tehran, Iran

Purpose: The present study aimed to investigate the relationship between depression and sexual function in women with recurrent pregnancy loss. Methods: In a cross-sectional correlational study, 130 consecutive patients with history of recurrent pregnancy loss were included who referred to Avicenna Fertility Center in Tehran, Iran during November 2018-February 2019. The outcomes were sexual dysfunction (Assessed with the Female Sexual Function Index) and depression (Evaluated with the Beck's Depression Inventory). The study data were analyzed by using Mann-Whitney and Kruskal-Wallis tests. Results: The study findings revealed that 40.8% of the participants suffered from some degrees of depression. The data analysis revealed that depression had a significant inverse correlation with sexual function and its domains (r = - 0.392, p < 0.001, R2= 0.15). The spouse' education level and economic status demonstrated a significant relationship with women's sexual function (p = 0.01, p = 0.033). A significant relationship was also detected between women's depression and economic status (p = 0.028). Conclusions: The study findings showed that women with RPL who had severe depression indicated lower score of sexual function. Since psychological and sexual problems are not reported to health care providers due to giving priority to fertility issues or considering such issues as taboos, the assessment of sexual and mental health needs to be part of the consultation in women with history of RPL, whether the patient seeks help for depression and sexual dysfunction or not

Modelling, analysis, and implementation of a switched-inductor based DC/DC converter with reduced switch current stress

This paper proposes a technique for switch current stress reduction in a Switched Inductor DC-DC Boost Converter (SIBC). The proposed technique comes up with a low-cost design, high voltage conversion ratio with a less duty cycle value, and lower current stress without increasing the component count. This topology is basically a transformer-less design where one diode of the traditional switched inductor configuration has been replaced with a switch, which is in parallel with the existing switch, resulting in a design that can incorporate active switches with a low current rating, since the total input current is equally shared by them. The detailed modes of operation in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) and steady-state analysis, the non-idealities' effect on voltage gain, design approach, and a comparative study with other DC-DC converters for some significant performance characteristics are provided. The experimental validations for the performance and working of the 500 W designed prototype are presented.This publication was made possible by Qatar University-Marubeni Concept to Prototype Development Research grant no. M-CTP-CENG-2020-2 from the Qatar University.Scopu

Double stage converter with low current stress for low to high voltage conversion in nanogrid

A low to high voltage conversion technique has been proposed in this paper using double stages of switched inductors for nanogrid applications. The proposed converter topology utilizes fewer components, achieves high voltage gain at a small value duty ratio, and has high efficiency. Moreover, the proposed converter provides a reduced switch current stress to obtain a stable constant boosted DC voltage. Therefore, it requires low-current rating switches and hence leads to cost reduction. Additionally, the load and the source end are connected to the same ground. The principle of operation, theoretical waveforms in Continuous Conduction Mode (CCM), and Discontinuous Conduction Mode (DCM) with steady-state analysis are discussed. A detailed discussion about the effect of non-idealities on the high voltage conversion, the design of components, and a comparison of the performance characteristics such as the number of components, Voltage Gain in CCM, switch current stress, normalized switch voltage stress, and efficiency of the proposed converter topology with other converters are presented. The experimental results of the 500W laboratory prototype are also shown to validate the operation of the proposed converter.This publication was made possible by Qatar University- Marubeni Concept to Prototype Development Research grant # [M-CTP-CENG-2020-2] from the Qatar University. The statements made herein are solely the responsibility of the authors. Open Access funding is provided by the Qatar National Library.Scopu

A Novel Modified Switched Inductor Boost Converter with Reduced Switch Voltage Stress

Recently, switched inductor (SI) and switched capacitor techniques in dc-dc converter are recommended to achieve high voltage by using the principle of parallel charging and series discharging of reactive elements. It is noteworthy that four diodes, one high-voltage rating switch, and two inductors are required to design classical SI boost converter (SIBC). Moreover, in classical SIBC, the switch voltage stress is equal to the output voltage. In this article, modified SIBC (mSIBC) is proposed with reduced voltage stress across active switches. The proposed mSIBC configuration in this article is transformerless and simply derived by replacing the one diode of the classical SI structure with an active switch. As a result, mSIBC required low-voltage rating active switches, since the total output voltage is shared into two active switches. Moreover, the proposed mSIBC is low in cost, provides higher efficiency, and requires the same number of components compared with the classical SIBC. The continuous conduction mode and discontinuous conduction mode analysis, the effect of nonidealities on voltage gain, design methodology, and comparison are presented in detail. The operation and performance of the designed 500-W mSIBC are experimentally validated under different perturbations.Manuscript received July 14, 2019; revised October 15, 2019 and December 13, 2019; accepted January 3, 2020. Date of publication February 5, 2020; date of current version October 30, 2020. This work was supported by Qatar University High Impact under Grant QUHI-CENG-19/20-2, from the Qatar University. The publication charges are funded by the Qatar National Library. The statements made herein are solely the responsibility of the authors. (Corresponding author: Atif Iqbal.) S. Sadaf, M. Meraj, A. Iqbal, and N. Al-Emadi are with the Department of Electrical Engineering, Qatar University, Doha 2713, Qatar (e-mail: [email protected]; [email protected]; [email protected]; [email protected]).Scopu

A Novel Modified Switched Inductor Boost Converter with Reduced Switch Voltage Stress

DC-DC power converters are necessary to step-up the voltage or current with high conversion ratio for many applications e.g. photovoltaic and fuel cell energy conversion, uninterruptible power supply, DC microgrid, automobile, high intensity discharged lamp ballast, hybrid vehicle, etc. in order to use low voltage sources. In this project, a modified SIBC (mSIBC) is proposed with reduced voltage stress across active switches. The proposed mSIBC configuration is transformer-less and simply derived by replacing one diode of the classical switched inductor structure with an active switch. As a result, mSIBC required low voltage rating active switches, as the total output voltage is shared between two active switches. Moreover, the proposed mSIBC is low in cost, provides higher efficiency and required the same number of components compared to the classical SIBC. The experimental results are presented which validated the theoretical analysis and functionality, and the efficiency of the designed converter is 97.17%. The proposed mSIBC converter provides higher voltage conversion ratio compared to classical converters e.g. boost, buck-boost, cuk, and SEPIC. The newly designed configurations will aid the intermediate power stage between the renewable sources and utility grid or high voltage DC or AC load. Since, the total output voltage is distributed among the two active switches, low voltage rating switches can be employed to design the power circuit of the proposed converter. The classical boost converter or recently proposed switched inductor based boost converter can be replaced by the proposed mSIBC converter in real-time applications such as DC microgrid, DC-DC charger, battery backup system, UPS, EV, an electric utility grid. The proposed power circuitry is Cost effective, Compact in size, easily diagnostic, highly efficient and reliable

New High Gain 2LC-Y Multilevel-Boost-Converter (2LC-Y MBC) Topologies for Renewable Energy Conversion: Members of X-Y Converter Family

This paper presents a new high gain 2LC-Y Multilevel-Boost-Converter or 2LC-Y MBC topologies for renewable energy conversion. Four new topologies 2LC-L MBC, 2LC-2L MBC, 2LC-2LC MBC, and 2LC-2LCm MBC are developed by combination of the voltage multiplier characteristics and the traditional 2LC-Y topologies of XY family (2LC-L, 2LC-2L, 2LC-2LC, and 2LC-2LCm) to achieve high voltage gain. These topologies are beneficial when used in applications where low to high voltage conversion is required, which makes it suitable for renewable energy applications like photovoltaic systems, fuel-cell system, hybrid vehicle, HVDC, and DC drives etc. Additionally, a stack of multiple capacitors present at the output side makes the proposed topologies highly suitable for utility grid using multilevel inverter (MLI). The operating principle of proposed 2LC-2LCm MBC topology is explained in detail and voltage gain analysis of the proposed converters is presented. Moreover, all the proposed topologies are compared with each others in terms of voltage gain. The simulation results validated the operation of the proposed converter and perfectly matching with the theoretical analysis. - 2019 IEEE.ACKNOWLEDGMENT This publication was made possible by High Impact grant # [QUHI-CENG-19/20-2] from the Qatar University. The statements made herein are solely the responsibility of the authors.Scopu

A New Type of Boost Converter with Dual Duty and High Gain for DC Microgrid Applications

A new high-gain Switched Inductor DC/DC Boost converter with dual duty is proposed in this paper for DC Microgrid applications. Two non-isolated inductors forming a switched inductor structure have been incorporated in the proposed topology, which is being charged in parallel and discharged in series. There are three working modes of the proposed converter which are controlled by two switches with two distinct duty cycles of low values to utilize a broad duty cycle range. A dual-duty converter exhibits flexibility in duty cycle selection as compared to a single duty converter for the switch to attain the required level of output voltage and controls the magnitude of inductor current ripple by selecting the duty cycle values appropriately. The dual-duty control property of the proposed converter facilitates the control through multiple control options. The benefits of the proposed circuit are 1) Dual duty ratio control and the high voltage gain, 2) Continuous input current, 3) Load and source ends are connected to a common ground. The circuit description, working theory, analysis of voltage gain in steady-state during the continuous conduction mode (CCM), mathematical analysis, and experimental results are presented for the proposed converter topology. To experimentally analyze and validate the performance of the proposed converter a prototype (500 W) is developed in the laboratory. 2022 IEEE.ACKNOWLEDGMENT This publication was made possible by Qatar University-Marubeni Concept to Prototype Development Research grant # [M-CTP-CENG-2020-2] from the Qatar University. The statements made herein are solely the responsibility of the authors.Scopu

Techniques to Reduce Capacitor Voltage Ripples in Multilevel Inverters

Reducing ripples on the capacitor voltage has two benefits: improved output waveform quality and accurate converter size. During the generation of a given output voltage level, the factor “Inherent Redundant Paths (IRPs)” has a considerable impact on the characteristics of multilevel inverter design. The consistent distribution of power loss derives from the Active Neutral Point-Clamed Inverter’s intrinsic redundant route at zero-voltage level generation. Even though it has been claimed that adding intrinsically redundant routes might give fault-tolerance capabilities to MLI topologies, the utilization of these pathways at intermediate voltage levels has not yet been studied. Based on this, the current research provides a unique charging and discharging technique is known as the alternating charging and discharging approach, which reduces capacitor voltage ripple. In addition, the suggested technique permits the inherent voltage balancing of capacitors without the need for supplemental components. The suggested alternative charging and discharging approach is implemented under both healthy and varied switch failure circumstances. In a laboratory prototype, the efficacy of the suggested alternative charging and discharging technique has been empirically tested