Voltage Conversion Research Articles

Isolated FeN3 sites anchored hierarchical porous carbon nanoboxes for hydrazine‐assisted rechargeable Zn‐CO2 batteries with ultralow charge voltage

AbstractZn‐CO2 batteries (ZCBs) are promising for CO2 conversion and electric energy release. However, the ZCBs couple the electrochemical CO2 reduction (ECO2R) with the oxygen evolution reaction and competitive hydrogen evolution reaction, which normally causes ultrahigh charge voltage and CO2 conversion efficiency attenuation, thereby resulting in ~90% total power consumption. Herein, isolated FeN3 sites encapsulated in hierarchical porous carbon nanoboxes (Fe‐HPCN, derived from the thermal activation process of ferrocene and polydopamine‐coated cubic ZIF‐8) were proposed for hydrazine‐assisted rechargeable ZCBs based on ECO2R (discharging process: CO2 + 2H+ → CO + H2O) and hydrazine oxidation reaction (HzOR, charging process: N2H4 + 4OH− → N2 + 4H2O + 4e−). The isolated FeN3 endows the HzOR with a lower overpotential and boosts the ECO2R with a 96% CO Faraday efficiency (FECO). Benefitting from the bifunctional ECO2R and HzOR catalytic activities, the homemade hydrazine‐assisted rechargeable ZCBs assembled with the Fe‐HPCN air cathode exhibited an ultralow charge voltage (decreasing by ~1.84 V), excellent CO selectivity (FECO close to 100%), and high 89% energy efficiency. In situ infrared spectroscopy confirmed that Fe‐HPCN can generate rate‐determining *N2 and *CO intermediates during HzOR and ECO2R. This paper proposes FeN3 centers for bifunctional ECO2R/HzOR performance and further presents the pioneering achievements of ECO2R and HzOR for hydrazine‐assisted rechargeable ZCBs.

The reflections on energy costs and efficacy problems of modern LED lamps

Currently the technology of electroluminescent light sources has undoubtedly dominated the lighting market and LED lamps are replacing the traditional light sources which are being withdrawn from the market. Powering light-emitting diodes requires the use of the appropriately selected power supply systems. All power supply solutions use electronics, mainly voltage converters, which can generate much capacitive reactive power that may cause a contractual penalty in settling electricity costs. Therefore, using LED lamps may lead to an unnecessary increase in electricity bills. This paper presents the basic information about modern types of LED lamps with the Edison E27 base. The definition and basic requirements for the power factor for LED lamps and problems related to it are also discussed. The basic electrical and photometric parameters were measured for the selected 77 samples of LED lamps available on the market in 2023. The conducted research has shown that the average luminous efficacy of LED lamps with the power ranging from 4 W to 20 W is 105 lm/W. However, the power factor most often ranges from 0.5 to 0.6 (68 % of cases). The novelty of this paper is related to presenting the complete operation costs of LED lamps considering reactive energy. In the case of the conducted research, on average, a five-fold increase in the costs of using the LED lamp in an annual cycle was proved. It is mainly related to the low power factor issue and the requirements of this parameter needing to be more restrictive. Therefore, the need to introduce alternative, more stringent requirements related to the power factor of LED lamps was proven and proposed. The new approach to the definition of the luminous efficacy of an LED lamp by referring to its power factor or apparent power as well as tips helpful to users choosing an LED lamp, can also be found in this paper.

Water Quality Analysis of a 300 Mvar Large-Scale Dual Internal Water Cooling Synchronous Condenser External Cooling System and Exploration of Optimal Water Treatment Agent Dosage at Different Temperatures

The external cooling water system of a 300 Mvar dual internal water cooling synchronous condenser at a certain ultra-high voltage converter station continued to exhibit significant scaling and corrosion, even with regular addition of scale and corrosion inhibitors. To solve this problem, the external cooling water of the synchronous condenser was sampled and tested periodically, with the main test items including conductivity, pH value, turbidity, hardness, alkalinity, and other water quality parameters directly related to corrosion and scaling. The trends of these parameters over time were also analyzed. The results showed that as the operation time increased, the cooling water became concentrated during multiple circulation cycles, and the various dissolved or suspended substances underwent a certain degree of enrichment. However, the addition of scale and corrosion inhibitors did not dynamically adjust according to the changes in water quality, and there was always an excessive dosage. Thus, using the external cooling water as the experimental sample, static scale inhibition tests and rotating coupon corrosion tests were conducted to evaluate the scale and corrosion inhibition performance of the commercial AS-582 scale and corrosion inhibitor used at this ultra-high voltage converter station under different conditions. Considering the more obvious corrosive tendency of this water sample, the focus was on testing its corrosion inhibition performance. When the dosage was 600 ppm, the scale inhibition effect was optimal, with an inhibition rate of 92.15%. The corrosion inhibition effect of this scale and the corrosion inhibitor were significantly related to water temperature. At 25 °C, when the dosage was 500 ppm, the corrosion inhibition effect was optimal, with an inhibition rate of 86.79%. However, when the temperature increased to 40 °C, the corrosion inhibition effect under each dosage was significantly worse, unable to meet the requirements, and the use of other corrosion inhibitors in combination was necessary. This work will provide a reference for the scientific use of scale and corrosion inhibitors.

Enhancing hole-transport efficiency in (CH3NH3)2CuClxBr4-x perovskite solar cells through functionalization of multi-walled carbon nanotubes

This study addresses the conductivity limitation of conventional hole-transporting layers (HTLs) like Spiro-OMeTAD in perovskite solar cells. We integrate functionalized multi-walled carbon nanotubes (MWCNTs) into Spiro-OMeTAD and examine the impact of chemical oxidation/functionalization of MWCNTs on their application in perovskite solar cells. Various ratios of H2SO4/HNO3 mixture were employed to functionalize MWCNTs, with FTIR analysis confirming functional group attachments on the nanotube walls. Raman spectroscopy was utilized to analyze defect formation in the MWCNTs, while FESEM images displayed both the tubular structure and morphological alterations resulting from functionalization. XRD analysis was conducted to examine the structural variances resulting from different functionalization ratios. A lead-free copper-based perovskite (CH3NH3)2CuBr4-xClx (x = 0.5), synthesized via a straightforward solution method, served as the active material for solar cells. The XRD assessment of the active material confirmed perovskite formation, with morphological analysis revealing a layered structure. Diffuse Reflectance Spectroscopy (DRS) measurements yielded a bandgap of approximately 1.86 eV for the perovskite. Dark I–V measurements were executed for Spiro-OMeTAD films incorporated with pure and functionalized MWCNTs, showcasing improved conductivity attributed to charge carrier conduction via defect passivation. Hybrid solar cells were fabricated with structures such as TiO2/(CH3NH3)2CuBr4-xClx (x = 0.5)/Spiro-OMeTAD/Ag, and TiO2/(CH3NH3)2CuBr4-xClx (x = 0.5)/functionalized MWCNTs/Spiro-OMeTAD/Ag. These cells demonstrated enhanced stability, retaining over 65 % of their initial efficiency after 10 days of storage, attributed to improved moisture permeability inferred from contact angle measurements and XRD analysis. Photovoltaic characterization revealed significant improvements in fill factor (∼70 %), short-circuit current density (2.94 mA), open-circuit voltage (0.70 V), and power conversion efficiency (PCE) (1.6 %) for the FTO/TiO2/(CH3NH3)2CuCl0·5Br3.5/Spiro-MWCNT-1/Ag device.

Analytical Modeling and Comparison of EMI pre-filter Noise Emissions of Three-Phase Voltage and Current DC-Link Converters

Analytical Modeling and Comparison of EMI pre-filter Noise Emissions of Three-Phase Voltage and Current DC-Link Converters

Highly Sensitive Phased Array Probes based on Capacitive Micromachined Ultrasonic Transducers

Capacitive Micromachined Ultrasonic Transducers (CMUTs) offer a wide freedom of design for ultrasonic phased arrays. They are characterized, in comparison to piezoelectric transducers, by a higher sensitivity in receiving and a wider bandwidth based on their physical properties. Especially in combination with integrated preamplifiers the high receiving sensitivity compensates or rather overcompensates the lower transmission power of the CMUT in single probe applications with pulse-echo technique. This asymmetric behavior opens new opportunities in the application. In medical diagnostics it allows to meet the maximum permissible ultrasonic radiation force with the best sensitivity. In nondestructive testing the transmission power can be increased by the combination of a piezoelectric probe for transmitting and a CMUT probe for receiving. Especially in double probe techniques, such as pitch-catch or time-of-flight diffraction (TOFD), this is an efficient extension of the conventional approach with two piezoelectric transducers. The CMUT array probes developed by Fraunhofer IPMS with integrated preamplifier and bias voltage converter powered by a standard USB-A connector can be applied as one to one substitute for piezoelectric phased arrays with commercially available ultrasonic devices without adaption or additional electronics. The CMUT arrays are best suited for immersion technique and medical sonography because of their natural matching to water-like materials. They are applicable as well for solid surfaces with a special coating. We present the first results of ultrasonic imaging with our CMUT array probes in comparison with a commercially available piezoelectric phased array probe.

Development of a control algorithm for a boost converter with the possibility of dynamic correction of control system parameters

RELEVANCE of the study lies in the development of an algorithm for controlling a DC voltage converter capable of providing a high-quality transient process with a wide change in the input parameters of the control object, affecting its nonlinear properties. purpose. THE PURPOSE. To consider methods for the development of continuous and discrete control systems for a step-up DC voltage converter and to obtain an analytical dependence of accounting for the nonlinear properties of the converter that affect the quality of regulation of the output voltage of the voltage stabilizer METHODS. The method of the average geometric root was chosen as a method for calculating the coefficients of the DC voltage converter control system, and the current circuit is adjusted using the technical optimum method, and the voltage circuit using the symmetric optimum method. The obtained analytical solutions of mathematical models and simulation models were compared in the SimInTech software environment. results. RESULTS. The simulation results show that the analytical solution of the mathematical model of the voltage stabilization system has a shorter transition time than the simulation results. This is due to the fact that in the mathematical model according to which the continuous control algorithm was synthesized, the presence of a power input filter, as well as the degree of their precharge, is not taken into account. Because of this, the transition time on simulation models is slower, applied 4 times than in the mathematical model. conclusion. CONCLUSION. When comparing the algorithms with each other, it can be seen that the algorithm obtained by converting a continuous algorithm by the Tusten method has the shortest transition time than all other algorithms. The continuous algorithm and the algorithm obtained by the inverse Euler transformation method have a speed close to each other, and the algorithm obtained by the direct Euler transformation turns out to be the slowest.

Addressing output ripples in low-power CMOS-based multistage DC-DC boost converters for self-powered electrochemical sensors applications

In modern electronic systems, the DC-DC converter plays a pivotal role by facilitating the conversion of direct current (DC) from one voltage level to another. Given the diverse voltage requirements of contemporary chips, a single chip may encompass multiple circuitry groupings, each necessitating specific voltage levels for optimal functionality. To address this need, voltage converters are essential, whether it involves increasing the voltage (Boost converter), decreasing the voltage level (Buck converter), or performing both functions (Buck-boost converter). This paper presents a novel multistage DC-DC converter designed to minimize voltage ripples. The proposed three-stage DC-DC converter is supplied with a 1.5-V input and achieves a four-boost ratio. The cascaded architecture integrates switching capacitors and a gyrator, complemented by a terminating low-pass filter, resulting in a minimal voltage ripple of 0.0003 % relative to the maximum output voltage. Notably, integrating the gyrator enables an inductorless CMOS-based architecture, significantly reducing layout area to 30 × 140 μm2. Furthermore, the converter's transient response was simulated, yielding a response time of 90 ms.

Self-powered wireless sensor system utilizing a thermoelectric generator for photovoltaic module monitoring application

In this work, we demonstrate a self-powered wireless PV module monitoring system that utilizes a thermoelectric generator (TEG) to convert residual thermal energy from the PV module into electrical power. We investigated the TEG performance with and without the heat sink. Results show that the temperature difference between the hot and cold sides of the TEG increased to 7.2 °C with the heat sink, compared to only 1 °C without it, at a hot side temperature of 50 °C. We integrated the TEG/heat sink with the PV module, which served as the heat source, achieving a maximum output power of 0.981 mW at a voltage of 0.06 V under a temperature gradient of 3.6 °C in a 1 sun condition. We successfully demonstrated a self-powered wireless PV monitoring sensor system by integrating a step-up voltage converter, microcontroller, IR thermometer, Bluetooth communication module, and the TEG/heat sink, which generated sufficient power for the monitoring system operation. The findings introduce a novel solution for wireless PV module monitoring that operates independently of grid connections or battery power. This innovation not only signifies advancements in renewable energy management but also opens new opportunities in the Internet of Things (IoT) sector.

КЕРУВАННЯ ДИНАМІКОЮ ІМПУЛЬСНОГО ПЕРЕТВОРЮВАЧА З М’ЯКИМ ПЕРЕМИКАННЯМ, ЩО ПРАЦЮЄ НА ДУГОВЕ НАВАНТАЖЕННЯ

Issues of design and research of energy-efficient and reliable semiconductor DC voltage converters for wide application in power supply devices of arc plasmatrons used in plasma metal cutting installations are considered. An estimated structural dynamic model of a soft-switching DC converter with a closed-loop control system combining the power part and the control system, intended for use as part of the latter as a digital module, was built. A technique is proposed and methods of controlling the converter are found, which provide the specified duration of transient processes, the permissible value of load current pulsations in a quasi-steady mode and the astatism of the output current, which confirms the correctness of the proposed technique. A prototype of a pulse stabilizer with digital control was made. The results of experimental studies of the sample confirm the effectiveness of the developed control device, namely the achievement of the specified duration of transient processes caused by a step change in the load current, close to 10-12 periods of conversion and astatism of the output current. It is shown that the application of a pulse stabilizer, in which a digital control loop is used, has significant advantages compared to analog options and has the advantages of a strategic plan. The use of combined control allows you to significantly reduce the requirements for the overall gain of the main control channel, which greatly facilitates the choice of sequential digital correction. Research results may be of interest to specialists in the field of power electronics, power supply systems of autonomous objects and control systems. References 14, figures 11. Key words: automatic control system, digital controller, external disturbance, plasma, robustness, optimization.

Design of Level Sensor Prototype for Fuel Tank in Base Transceiver Station Facilities

A monitoring system for fuel availability at Base Transceiver Stations (BTS) is an absolute necessity. The fuel availability in the generator set must be guaranteed because it ensures the energy supply and continuous operation. This research purpose is to create a robust and effective sensor that can be monitored in real-time so that industry players can estimate the consumption of fuel at the BTS in a certain period. The novelty of this research is that instead of looking at the amount of fuel consumption/reduction like the previous research, this study focuses on how much diesel availability is in the generator tank. So, calculating fuel requirements and predicting actual consumption are done directly. The sensor is a reed-switch oil level sensor and is connected to ESP32 as the microcontroller. It's installed horizontally and uses an optimum distance between sensors of 2.5 mm to improve the sensor reading's accuracy. The test results of converting voltage values into ADC signals on sensor readings produced a determination coefficient of 0.9987, which showed the reliability of the sensor-level design. The sensor precision test results produced an RSD value of 0.17% and the accuracy test produced an error range of -3% to 2% with an average error value of 1.59%. These results indicate that the designed level sensor has good precision and accuracy. Through this research, the provider can predict and plan their fuel consumption needs for BTS power supply and increase the Domestic Component Level in the sensor industry.

Structural Modeling of Fluorinated Quinoxaline Core–Based Chromophores for Efficient Photovoltaic Materials: A DFT Study

ABSTRACTHerein, a series of fluorinated quinoxaline core–based chromophores (MTH1‐MTH6) with A1–π–A2–π–A1 configuration was designed by structural modulation of end‐capped acceptors in MTHR. The quantum chemical calculations were accomplished at MPW1PW91/6‐311G(d,p) functional to explore optoelectronic and photovoltaic properties of these designed compounds. The findings revealed that all the derivatives exhibited narrow band gap (Egap = 2.163–2.666 eV) with red shift spectra (610.24–766.944 eV in chloroform) as compared with MTHR. The designed compounds exhibited comparable open‐circuit voltage (Voc) and higher power conversion efficiencies (PCEs) as compared with the MTHR. Among the entitled chromophores, MTH1 was found to be a promising chromophore for organic solar cells (OSCs) owning to its lowest Egap (2.163 eV) with highest absorption peak (766.944 nm in chloroform and 717.709 nm in gaseous phase). The aforementioned findings indicate that molecular engineering of chromophores with extended acceptors enhances photovoltaic response, and this motivates researchers to develop highly effective photovoltaic devices.

Investigation on indium concentration in two-terminal tandem indium gallium nitride solar cells by SCAPS-1D

Indium gallium nitride (InGaN) thin-film solar cell is a promising photovoltaic (PV) device. InGaN’s bandgap is tunable from 0.7 to 3.4 eV and it exhibits a high absorption coefficient exceeding 105 cm−1. Besides, InGaN solar cells can be used in tandem configuration, to effectively absorb the solar spectrum. Previous works found that increased indium (In) concentration leads to inverse relationship between open-circuit voltage (Voc) and power conversion efficiency (PCE) of the solar cell. This leads to deleterious device performance. This study aims to assess the performance of two-terminal InGaN tandem solar cells using SCAPS-1D simulation software. The findings revealed maximum short-circuit current density (Jsc) of 26.19 mA cm−2, open-circuit voltage (Voc) of 2.13 V, fill factor (FF) of 89.68%, and PCE of 30.17% from the tandem device. The results indicate that higher In concentration enhances light absorption and the overall PCE, with tandem cells outperforming single-junction cells. This study makes a valuable contribution to the advancement of high-efficiency solar technology based on InGaN.

A soft switching non‐isolated bidirectional DC–DC converter with improved voltage conversion ratio and minimum number of switches

AbstractA soft switching non‐isolated bidirectional DC–DC converter with an improved voltage conversion ratio without any additional auxiliary switch is presented in this paper. In the proposed converter, improved step‐up/step‐down gain conversion is achieved by employing the coupled inductors method. Also, the auxiliary circuit provides soft switching conditions for all the semiconductor elements, regardless of the power flow direction and without any extra voltage stress. The other switch helps provide soft switching conditions for the main switch. Moreover, the switch used for providing soft switching conditions operates as a synchronous rectifier as well. The additional circuit added to attain soft switching is composed of an inductor, coupled with the converter's main inductor, and two auxiliary diodes. The auxiliary diodes benefit from zero‐current‐switching conditions. Fully soft switching conditions for all semiconductor devices, removing the reverse recovery problem, and a low number of components have led to mitigating switching losses and improving efficiency. Detailed operating principles and a theoretical analysis of the proposed converter are presented. Also, the experimental results of a 220 W prototype circuit are provided to confirm the validity of the proposed topology.

Design and Analysis of a Novel Bidirectional DC‐DC Converter With Ultra‐Conversion Ratio and Reduced Current Stress

ABSTRACTConventional nonisolated bidirectional DC‐DC converters are limited because of their low conversion voltage ratio. To overcome the limitation, this paper proposed a new bidirectional DC‐DC converter to introduce the novel regenerative configuration merged with the switched inductor technique for high voltage conversion applications. This design enables extreme DC‐voltage conversion with a minimal number of semiconductors and passive components. As a result, the converter's cost is reduced, and it can attain a high voltage gain with less duty ratio. In general, ultra‐gain converters suffer from high current stress across the input and output side switches in the step‐up and step‐down modes. To reduce high current stress, an active network configuration is imposed in the proposed converter. This paper describes the operating principle, steady‐state analysis of the voltage gain, and presents the performance matrices of the proposed converter. Furthermore, a comparative analysis is made with conventional and recent literature converters. Finally, a 350‐V, 500‐W, and 20‐kHz experimental prototype has been fabricated to validate the operation and corroborate the theoretical waveforms with experimental results.

A non‐isolated single‐input dual‐output DC–DC boost converter with high‐voltage gain

AbstractThis paper presents a new structure of a high step‐up DC–DC converter. The proposed converter has one input and two outputs with different voltage levels, suitable for applications that require multiple voltage levels such as photovoltaic systems, electric vehicles and DC microgrids. The proposed converter is expandable to more outputs and has a higher voltage conversion ratio compared to similar converters. The operational modes of the proposed converter are investigated and the conversion ratio of the converter is obtained. Additionally, small‐signal equations of the converter are derived, and using state‐space matrices, transfer functions of the converter are obtained and the controller is designed. Also, the proposed converter is compared with similar converters and power losses equations of the converter are derived. To investigate the converter's performance, simulations are done using MATLAB/Simulink software. Moreover, to validate the theoretical analysis, a laboratory prototype is implemented. The obtained results confirm the operation of the proposed converter.

Improved ultra voltage gain switched inductor based-Y-Source DC/DC converter with low device stress

ABSTRACT This article proposesanImproved ultra-high voltage gain Switched Inductor-Based Y-Source Converter (SI-YSC) forphotovoltaic (PV) and Fuel Cell (FC) applications. A single switch is employed to generate a high voltage boost at the load, and this topology provides a high voltage conversion ratio, minimal voltage stress on the switch, and continuous input current. The paper comprehensively examines passive components’ steady-state operation, design, and analysis. In addition, in order to comprehend the projected lifespan of the topology in different environments and operating conditions, the converter’s reliability is assessed to determine the mean time to failure of each component. To demonstrate the advantages of the proposed topology, an in-depth comparison is conducted between it and other Y source converters. The circuit design is verified using MATLAB/Simulink and a prototype model for an output power of 100 W. The results of this verification process are then analysed and discussed.

Physics-Informed Machine Learning with Data-Driven Equations for Predicting Organic Solar Cell Performance.

Organic solar cells (OSCs) have emerged as a promising solution in pursuing sustainable energy. This study presents a comprehensive approach to advancing OSC development by integrating data-driven equations from quantum mechanical (QM) descriptors with physics-informed machine learning (PIML) models. We circumvent traditional experimental limitations through high-throughput QM calculations, prioritizing transparent and interpretable models. Using the SISSO++ method, we identified key descriptors that effectively map the relationships between input variables and photovoltaic performance metrics. Our innovative predictive models, derived from SISSO outputs, excel in forecasting critical OSC parameters such as short-circuit current (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCEmax), achieving high accuracy even with limited data sets. To validate our models' practical utility, we applied the PIML framework to a newly compiled data set of OSC devices, demonstrating their versatility and capability in pinpointing high-performance materials. This research underscores the strong predictive power of our models, bridging the gap between experimental results and theoretical predictions and making significant contributions to the advancement of sustainable energy technologies.

A New Wide Range and High Voltage Conversion Bidirectional DC/DC Converter for DC Microgrid

ABSTRACTBidirectional DC/DC converters (BDCs) are crucial in energy storage integration with DC microgrid. In this article, a new wide‐range and high voltage conversion (VC) nonisolated BDC with simple structure having reasonable components (total 13) is proposed. The proposed BDC with symmetrical VC ratio delivers high conversion of voltage within the vicinity of 0.5 duty ratio in both boost and buck modes of operation. In addition, the proposed BDC has features of continuous currents at low and high voltage stages and reduced switch voltage stress. This article presents the proposed BDC with circuit configuration and its detailed steady‐state boost and buck mode analyses to verify achievable VC ratio and design consideration. With the designed practical model of the proposed BDC, loss analysis is exhibited to verify the conversion efficiency in boost and buck modes of operation. In real time, experimental prototype of the proposed BDC is operated with LAUNCHXL‐F28379D kit to realize switching pulse generation. The experimental response of the entire proposed BDC operation is captured at 200 W loading. The attained experimental results and discussions validate the proposed BDC operation with the mentioned features. Finally, a comparative analysis with existing BDCs is performed to prove the competence of the proposed BDC for DC microgrid.

Distance preserving machine learning for uncertainty aware accelerator capacitance predictions

Abstract Accurate uncertainty estimations are essential for producing reliable machine learning models, especially in safety-critical applications such as accelerator systems. Gaussian process models are generally regarded as the gold standard for this task; however, they can struggle with large, high-dimensional datasets. Combining deep neural networks with Gaussian process approximation techniques has shown promising results, but dimensionality reduction through standard deep neural network layers is not guaranteed to maintain the distance information necessary for Gaussian process models. We build on previous work by comparing the use of the singular value decomposition against a spectral-normalized dense layer as a feature extractor for a deep neural Gaussian process approximation model and apply it to a capacitance prediction problem for the High Voltage Converter Modulators in the Oak Ridge Spallation Neutron Source. Our model shows improved distance preservation and predicts in-distribution capacitance values with less than 1% error.