Low Duty Ratio Research Articles

Response of variation of electrical control parameters to coatings prepared in organo-silicon electrolyte by plasma electrolytic oxidation

This study aims to explore the influence of control parameters from the perspective of the amorphous ceramic coating formation process. Three preparation processes were preferred based on the thickness, appearance and corrosion resistance of the coatings by orthogonal experiment. The surface morphology, cross-sectional structure, phase composition and micro-hardness of PEO coatings were examined using scanning electron microscopy (SEM)/Energy dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD) and hardness measurement techniques. Findings indicate that voltage exerts the most significant impact on coating thickness and appearance, whereas the influence of other parameters becomes more pronounced as the voltage increases. Three amorphous ceramic coatings prepared in 20 min with thicknesses of 27.4 μm, 83.2 μm and 193.3 μm increased the surface hardness of 6061 aluminium alloy by 6–8 times, and decreased the corrosion current density of 6061 aluminium alloy by 3 orders of magnitude in 1 mol L−1 HCl solution. Moreover, the thickening of the coating primarily occurs within a few minutes after the voltage reaches its peak, and high frequency and low duty ratio are prerequisites for better appearance under higher voltage conditions.

Atomic-scale understanding of microstructural evolution in electrochemical additive manufacturing of metallic nickel

Atomic-level manufacturing is fundamentally concerned with the precise removal, addition, and migration of material at the atomic and close-to-atomic scale (ACS). Tip-based electrochemical deposition, a quintessential ACS electrochemical additive manufacturing technique, offers promising prospects for achieving bottom-up fabrication of metallic micro/nano structures. However, the complex physicochemical reactions involved in electrodes lead to a limited understanding of the mechanisms underlying atomic electrodeposition and structural evolution. For the first time, this study proposes electric double-layer controlled electrochemical kinetics and investigates the effect of direct current (DC) and pulse current (PC) on nickel atomic electrodeposition using molecular dynamics (MD) simulations. The findings reveal that compared to DC electrodeposition, PC electrodeposition results in more orderly deposition morphology, improved surface smoothness, reduced dislocation density, and lower crystal distortion, with these effects being particularly pronounced under low pulse duty ratio conditions. In addition, the pulse frequency significantly influences the morphology and structure of the deposit. The high pulse frequency yields smoother surfaces with local protrusions, while the low frequency favors the formation of orderly and dense structures excepting slightly increased roughness. This study provides critical insights into understanding the microscopic mechanisms of atomic-scale electrodeposition processes and achieving atomically controlled tip-based electrochemical additive manufacturing of micro/nanodevices.

Switching Frequency Improvement of a High Speed on/off Valve Based on Pre-excitation Control Algorithm

The high-speed on/off valve (HSV) serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems. As the switching frequency of the HSV increases, the properties of the generated discrete fluid approach those of continuous fluids. Therefore, a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic systems. However, the current research mainly focuses on its dynamic performance, but neglect its FRC. This paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching time. The maximum switching frequency (MSF) is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio (SDR), whereas the closing dynamic performance limits the MSF when HSV operates with high SDR. Building upon these findings, the pre-excitation control algorithm (PECA) is proposed to reduce the switching time of the HSV, and consequently enhance its FRC. Experimental results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms, the closing delay time by 2.54 ms, and the closing moving time by 0.47 ms in comparison to the existing advanced control algorithms. As a result, a larger MSF of 417 Hz and a wider controllable SDR range from 20% to 70% were achieved at a switching frequency of 250 Hz. Thus, the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems.

Optimized ultra high voltage gain DC–DC converter with current stress reduction for photovoltaic application

AbstractThis paper presents a non‐isolated DC‐DC converter designed to validate ultra‐high voltage gain using a modified double boost mode. The objective is to achieve exceptionally high voltage gain by integrating a modified triple boost technique (MTBT), interleaved with second main and auxiliary third MOSFETs, and a modified switched inductor‐capacitor (MSLC), effectively doubling the voltage transfer gain. Furthermore, MSLC is combined with the auxiliary third and double main MOSFET to double the voltage gain while concurrently mitigating voltage stress on the auxiliary MOSFET and diodes in the proposed converter (the PC). Additionally, all diodes in the MTBT operate under zero current switching (ZCS) and the double main and auxiliary third MOSFET face very low current stress at ultra‐high voltage gain. The input current of the PC remains steady without pulsating at a low duty ratio, making the PC more suitable for renewable energy systems. The PC offers numerous advantages, exhibiting high efficiency and ensuring minimal voltage stress on power devices with low current stress on the power switches. Notably, PC aims to elevate input voltages from 30 V to a variable output range of 335 to 600 V, delivering 440 watts at 96.1% efficiency.

Switch-2 determines Mg2+ADP-release kinetics and fine-tunes the duty ratio of Dictyostelium class-1 myosins.

Though myosins share a structurally conserved motor domain, single amino acid variations of active site elements, including the P-loop, switch-1 and switch-2, which act as nucleotide sensors, can substantially determine the kinetic signature of a myosin, i.e., to either perform fast movement or enable long-range transport and tension generation. Switch-2 essentially contributes to the ATP hydrolysis reaction and determines product release. With few exceptions, class-1 myosin harbor a tyrosine in the switch-2 consensus sequence DIYGFE, at a position where class-2 myosins and a selection of myosins from other classes have a substitution. Here, we addressed the role of the tyrosine in switch-2 of class-1 myosins as potential determinant of the duty ratio. We generated constitutively active motor domain constructs of two class-1 myosins from the social amoeba Dictyostelium discoideum, namely, Myo1E, a high duty ratio myosin and Myo1B, a low duty ratio myosin. In Myo1E we introduced mutation Y388F and in Myo1B mutation F387Y. The detailed functional characterization by steady-state and transient kinetic experiments, combined with in vitro motility and landing assays revealed an almost reciprocal relationship of a number of critical kinetic parameters and equilibrium constants between wild-type and mutants that dictate the lifetime of the strongly actin-attached states of myosin. The Y-to-F mutation increased the duty ratio of Moy1B by almost one order of magnitude, while the introduction of the phenylalanine in switch-2 of Myo1E transformed the myosin into a low duty ratio motor. These data together with structural considerations propose a role of switch-2 in fine-tuning ADP release through a mechanism, where the class-specific tyrosine together with surrounding residues contributes to the coordination of Mg2+ and ADP. Our results highlight the importance of conserved switch-2 residues in class-1 myosins for efficient chemo-mechanical coupling, revealing that switch-2 is important to adjust the duty ratio of the amoeboid class-1 myosins for performing movement, transport or gating functions.

Damping monitoring methods during ultrasonic fatigue testing: A comparative study.

Ultrasonic fatigue testing is quite a useful tool for exploring the high-cycle and very-high-cycle fatigue properties of materials. Damping monitoring has been proved to be fairly effective in indicating the generated defects or damage in the testing specimen. In this work, two damping monitoring methods are comparatively studied, i.e., our recently proposed quantitative electromechanical impedance method and the traditional vibration-free decay method. Industrial pure copper and 6061 aluminum alloy are used for fatigue testing and damping monitoring. To exclude the differences of temperature effect on the testing system, the same duty ratio of 15.4% is employed in the ultrasonic fatigue testing. The results show that both methods can effectively monitor the system damping during testing and the damping evolution process just before failure. Specifically, the free decay method can obtain more damping data and has advantages in monitoring metals, such as aluminum alloys, whose fracture process is very quick. However, the system damping obtained by free decay is strongly dependent on the testing stresses and signal processing and is thus not suitable for failure prediction of specimens. In comparison, the system damping obtained by using the quantitative electromechanical impedance method is independent of the testing stresses. Thus, a definite relationship between the system damping and specimen's internal friction can be established. However, tens of seconds are required for accurate damping measurement using the quantitative electromechanical impedance method, leading to a low duty ratio of the ultrasonic fatigue testing. In practical, both the methods are suggested for monitoring of early damage during ultrasonic fatigue testing.

Design of fuzzy logic controlled zero voltage switching based interleaved high gain converter

The conversion of low level DC voltage to high level DC voltage at lower duty ratios with less ripple current at source side is a challenging task in the distributed generation systems. Active switched inductor (ASL) converter is a high gain converter and has a large amount of input ripple current due to the parallel charging of the inductors during on time of the switches and series discharge of the inductors during off time of the switches. This large input ripple current in the converter when used in distributed generation (DG) affects the life time of low voltage batteries and fuel cells, the efficiency of photovoltaic source, increases the size and losses in the filtering stages and decreases the power density of the converters. In this paper, soft switching of interleaved active switched inductor (IASL) through Zero Voltage Switching (ZVS) is designed to overcome the limitations of ASL. The performance is analyzed in terms of its gain, input current ripple, switching loss and efficiency. An M-type resonant switch is used to achieve soft switching through ZVS technique.A proper value of resonant elements (inductor and Capacitor) is designed to achieve ZVS to improve the efficiency. Regulated voltage of proposed converter is required in DG systems and is possible with closed loop control. Fuzzy Logic controller (FLC) is designed to regulate the voltage and its dynamic performance is analyzed for different load values and also for sudden changes in load. Hardware model of the proposed ZVS based IASL converter with FLC is implemented and the results are verified with simulation results obtained from MATLAB Simulink.

A High-Efficiency DC-DC Converter Based on Series/Parallel Switched Inductor Capacitors for Ultra-High Voltage Gains

A high-efficiency DC-DC converter employing a modified architecture called the hybrid switched inductor–capacitor series (MHSLCS) is proposed in this paper. The primary goal is to achieve a notably ultra-high voltage gain for renewable energy systems (RESs). Furthermore, the use of only one input capacitor in the MHSLCS eliminates pulsations in the input current at both low and high duty ratios. The proposed converter integrates the MHSLCS with a modified switched capacitor (MSC) that interleaves with the main MOSFET, effectively doubling the voltage transfer gain. Additionally, a modified hybrid switched inductor–capacitor parallel (MHSLCP) is incorporated in parallel with an interleaved auxiliary MOSFET. Both MOSFETs, combined with the MSC, contribute to achieving an ultra-high voltage gain. In addition, the inductors of the MHSLCP operate in a discontinuous conduction mode (DCM), which results in significant stress reductions in the power diodes and switches at high output voltages. The advantages of the proposed converter are multifaceted, demonstrating a high efficiency while minimizing the voltage in power device diodes and MOSFETs. The use of low inductance and capacitance values at high switching frequencies further enhances the performance. Wide-bandgap (WBG) power devices are employed to achieve the desired high voltage gain and efficiency. The proposed converter was designed with a PCB and underwent experimental testing to validate laboratory results. The proposed converter boosted the input voltage from 30 V to a variable output voltage between 325 V and 500 V, with a power output of 325 watts and an efficiency of 95.5%.

Characteristics of high-repetition-rate bipolar pulse DBD under various electrical conditions in atmospheric-pressure air

Numerous studies have been conducted on pulse dielectric barrier discharge (DBD) because it can produce powerful discharges uniformly at atmospheric pressure with a fast rise time. Although much research has been conducted on pulse DBD below 10 kHz, relatively little has been conducted on pulse DBD at high pulse repetition rates (PRRs). Therefore, in this study, the ozone generation and discharge characteristics of bipolar pulse DBD in atmospheric-pressure air at a high PRR of 10 kHz or above were investigated. According to the results of this study, with the exception of electron temperature, most discharge characteristics need for practical applications—like transfer charge, electron density, and discharge uniformity—improved as the voltage and duty ratio increased at high PRR. On the contrary, increasing the PRR exhibited trade-off features like low electron temperature, low discharge uniformity, and a high number of discharges per unit time. Ozone generation demonstrated good results at high voltage, appropriate PRR, and low duty ratio, but applying suitable electrical conditions is crucial considering ozone generation speed and power consumption. The findings of this study will be very beneficial for high-PRR pulse DBD applications that require quick and effective processing. Additionally, they will be useful for researching the characteristics of pulse DBD at high PRR.

Stability and reliability analysis of a non‐isolated high gain DC‐DC converter

AbstractThis paper investigates the stability and reliability analysis of a non‐isolated high‐gain DC‐DC converter. The proposed DC‐DC converter produces a high gain output voltage with a lower duty ratio and reduced voltage stress on the semiconductor switch. A reliability analysis is performed to predict the failure rate and lifetime of the individual components using the military handbook (MIL‐HDBK‐217F). A state space equation and small signal modeling of the proposed converter are derived to elucidate the performance of the proposed converter through stability analysis. A closed‐loop using PID controller is incorporated to attain the constant regulated output voltage during sudden parameter changes. The validation of the closed‐loop using the PID controller is verified with the wide range of variations in the different parameters, such as input voltage, load value, and reference voltage value. The laboratory‐based prototype is developed for the proposed converter and validated the performance with 250 W. The power density and efficiency of the proposed converter are 1.360 kW/L and 93%, respectively.

The influences of light scattering on digital light processing high-resolution ceramic additive manufacturing

Digital light processing (DLP) has emerged as a highly promising 3D printing technology, which is due to its ability to fabricate components and structures with low cost and high precision. The DLP is, therefore, applicable in a wide range of fields. The phenomenon of light-scattering plays a dominant role in the DLP manufacturing process, but the specific impact of ceramic particles on the distribution of incident light remains unclear. The present study has, therefore, focused on studying the effect of ceramic particles on light-scattering by performing extensive theoretical finite element simulations. The aim was then to improve the curing quality of the DLP 3D printing process. More specifically, spherically shaped particles with a uniform distribution, lower duty ratios, or materials with lower refractive indices were necessary conditions for enhancing the printing precision due to the mitigated lateral light scattering effects. The overall results of this study have provided valuable guidance for the control of the light-induced curing in the 3D printing process of ceramics, thereby facilitating advancements in ceramic-based fabrication techniques.

A New Triswitching Double Duty High Voltage Gain Boost Converter for DC Nanogrid Application

The Tri-switching Double Duty Converter (TSDDC) is a new non-isolated high gain DC-DC boost converter topology presented in this paper for 400V PV-based DC Nanogrid application. In a conventional DC nanogrid system, two DC-DC converter has been used, one for stepping up the voltage & the other for maximum power point tracking mechanism (MPPT). The proposed TSDCC can perform both operations in a single stage. The proposed converter has been controlled by two duty ratios ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\delta _{1}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\delta _{2}$</tex-math></inline-formula> ) with the help of three switches. The highlighting feature of TSDDC are i) Controlled on two different duty cycles ii) High voltage gain at low duty ratio iii) Lower voltage stress on switches and diodes. The TSDDC is simulated for 500W power with 400V. The working of the converter is explained in detail for continuous conduction mode (CCM). In addition, design guideline and comparative study are also presented. Furthermore, a control scheme is implemented that controls MPPT(maximum power point tracking). A lab prototype of TSSDC was developed for 21V-400V, 400W and the switching frequency is 50kHZ. The proposed TSDDC converter's operating concept and controllability are verified by the simulation results.

A High-Gain DC-DC Converter with a Wide Range of Output Voltage

In fuel-cell-powered electric vehicles, the output characteristics of the fuel cell are relatively soft, and the output voltage is unstable. Therefore, a DC-DC converter is required between the fuel cell and the inverter to transform the output voltage of the fuel cell into a suitable voltage for the motor drive. Existing non-isolated DC-DC converters cannot meet the requirements of high voltage gain, high efficiency and a wide range of output voltage simultaneously. To improve these performances, a high-gain DC-DC converter with a wide range of output voltage, based on a switched capacitor structure, is proposed in this paper. The converter supplies power to the load by connecting multiple capacitors with the input source in series in switch-on states, while the input source charges the capacitors through a series connection with an inductor in switch-off states. In comparison to existing converters, the proposed converter maintains high voltage gain at lower duty ratios and offers a wide range of output voltage. The operating principles, key waveforms and parameter design of the topology in Continuous Conduction Mode (CCM) are described and analyzed in detail, and the voltage gain of the proposed converter is compared with some other DC-DC converters. Finally, the results of simulations using Simulink and hardware experiments that were conducted to validate the theoretical analysis are described.

Reconfigurable high step‐up DC to DC converter for microgrid applications

AbstractHere, a high gain DC–DC converter which is based on switched capacitor (SC) and switched LCL (SLCL) cells is presented. The diode employed in the classical passive switched inductor (SI) cell is replaced by a capacitor in the proposed SLCL cell to achieve higher voltage gain. Two switches—one each in the positive and negative DC rails of the supply are employed to charge and discharge the inductors of SLCL cells. A generic structure comprising of N and M number of SLCL cells in the positive and negative DC rails respectively along with K number of SC cells is presented. To validate the proposed gain extension concept, a two‐switch based converter comprising of 2 SLCL and 1 SC cells is synthesized and its operation is described in detail. The voltage gain expression of the proposed SLCL‐SC converter is derived. Experimental results are obtained from a 25 to 380 V prototype converter which operates at a full‐load efficiency of 94.22% at 200 W. Since the switches employed in the proposed converter are operated at a moderate and safe duty ratio of D = 0.51, the voltage stress on the switches is about 25% of the output voltage while the diodes are subjected to even lesser voltage stress levels of only one‐fifth of the output voltage. The main salient features of the proposed topology are its (i) modular structure, (ii) ability to provide higher voltage gain values at lower duty ratios (iii) reduced voltage stress on the semiconductor devices and (iv) reduced conduction losses due to the replacement of diodes with capacitors in SLCL cells.

Design and implementation of single switch integrated boost and flyback converter for renewable and sustainable energy.

Renewable resources are being explored to meet the increasing energy demand in the world. The development of RES and their integration into the grid necessitate a voltage conversion to match with the grid voltage. This conversion can be implemented using DC-DC converters. A high-gain DC-DC Converter with low loss is proposed in this article. Thus, the proposed integrated converter is obtained by incorporating a boost converter at the primary side of the flyback converter (FLC) and a VM cell at the secondary side to perform a elevated voltage gain at a lower duty ratio. The Switched Capacitor network is implemented to elevate the voltage gain. The dynamic performance of a controller can be enhanced using an FOPID controller. A comparison analysis has been done using the most recent topologies in order to confirm the superiority of the Proposed converter. A 100W experimental prototype model has been constructed in order to further validate the simulation results. The efficiency of this converter is demonstrably significantly higher than the current topology, according to measured performance. Therefore, it can be said that this topology can be used for applications involving renewable and sustainable energy.

Fuel Cell Based Ultra-Voltage Gain Boost Converter for Electric Vehicle Applications

The proposed fuel cell-based ultra-voltage gain boost converter offers an alternative to transformer-based topologies for achieving high voltage gain. While transformers can achieve high voltage gains, they come with drawbacks such as high cost, design complexity, and increased weight. In this article, a switched inductor circuit is introduced as an alternative solution to achieve high voltage gain. This circuit enhances overall system performance by reducing size, weight, and cost. Operating in a transformer-less topology, the converter boosts voltage levels while ensuring low voltage stress on the switching devices. The suggested design enables larger voltage gain values even at low duty ratios. The output of the fundamental boost converter serves as the input for the switched inductor circuit, effectively boosting the voltage level and supplying more voltage to the output side. This converter is particularly suitable for applications requiring ultra-voltage gain in electric vehicles, which offer reduced pollution compared to internal combustion engines. Moreover, the utilization of this topology reduces space requirements. The article presents a thorough investigation of the steady state operation in continuous conduction mode, and theoretical verification and MATLAB simulations demonstrate the performance and operation of the proposed converter.

Fast response NLC controller for high gain QRC in wind connected DCMG with reduced steady-state error

ABSTRACT This paper proposes a system with Non-linear Carrier (NLC) controller for a high-voltage gain Quadrupler Converter (QRC). The system is 400 V DC Micro Grid (DCMG) with Wind Energy Conversion System (WECS). The quadrupler converter is a non-isolated topology that achieves single-stage high voltage gain with a low duty ratio and reduced voltage stress of semiconductor devices. The proposed system assures robust dynamics against changing operating conditions, variations in circuit parameters, and external load conditions. The parameters, such as voltage gain, voltage ripple, current ripple, delay time, settling time and peak overshoot, are assessed to ensure the agility of the proposed system. The performance of the proposed system is analysed with various wind speeds using Matlab Simulink-based simulation studies. The results inferred that the proposed method provides a fast response for various input and load variations and high gain at low duty ratio. A 200 W wind-connected QRC system with an NLC controller prototype is developed to validate the simulation results.

STEP-UP CONVERTER WITH HIGH VOLTAGE GAIN USING QUASI SWITCHED INDUCTOR AND CAPACITOR

This paper presents the design and simulation of the modified step-up converter with high voltage gain using quasi switched inductor and capacitor. High Voltage gain are the major requirements for renewable energy applications. The operating modes of the converter is analyzed and the proposed converter is simulated using MATLAB/SIMULINK platform. Key Words: High voltage gain, step-up converter, lower duty ratio.

Investigation of high-gain two-tier converter with PI and super-twisting sliding mode control

Power electronic converters are becoming more critical as renewable energy sources are linked to distributed generation systems. In this study, a “Two-Tier Converter” for high voltage gain with a low duty ratio, low voltage stress for the given voltage gain, continuous input current, and a grounded load arrangement have been made from two stages of a conventional boost converter. The analysis, modes of operation, and effects of the inductors’ internal resistances on voltage gain have been discussed. The advantages of the two-tier converter have also been established by comparison studies with other modern high-gain converters. The suggested converter has also been evaluated using stability analysis, PI, and super-twisting sliding mode control (STSMC) to regulate the output voltage at a constant value. The effectiveness of the suggested configuration with the suggested control approach has been demonstrated through simulation and experimental investigation.

A novel non-isolated high gain multiport DC-DC converter for integrating fuel cell/solar PV and battery energy storage system

ABSTRACT This paper presents a novel non-isolated capacitor-assisted quasi-Z-source (CA-QZS) multiport DC-DC boost converter, which operates as a dual-input single-output high gain boost converter. It consists of a bidirectional port for the smooth operation of the energy storage system, and a unidirectional port for the solar/fuel cell to deliver power to the battery and the load. The availability of common ground between input and output ports, high voltage conversion ratio, and continuous current of the unidirectional port are the main features of this novel design, making it suitable for a wider range of applications. A typical switching strategy is followed to regulate the output voltage as well as control input power from the sources. As a battery-incorporated system, the converter’s performance is determined by its selection between three operating modes. Therefore, the CA-QZS converter offers a viable interface for the management of battery energy storage systems. A comparative study is performed with other multi-port converters to highlight the advantages. It is observed that the voltage conversion ratio of 10, can be achieved at a low duty ratio of 0.3. To evaluate the effectiveness of the proposed topology, a prototype is developed with a nominal output power rating of 200W and an output voltage of 200 V.