Stable Output Voltage Research Articles

Long-Life flexible mild Ag-Zn fibrous battery with bifunctional gel electrolyte

Silver-zinc (Ag-Zn) fibrous batteries are considered as a promising power source for next-generation flexible/wearable electronics because of their superior safety, high energy density, and stable output voltage. Nevertheless, the widespread application of Ag-Zn batteries is hindered by their limited cycle life, primarily caused by Zn dendrite growth and Ag migration. Herein, we develop a flexible mild Ag-Zn fibrous battery with outstanding cycle performance via designing a bifunctional gel electrolyte. The graphene oxide (GO) introduced into the electrolyte provides dual enhancement in suppressing the growth of Zn dendrite and migration of Ag, leading to improved structural integrity and long cycle life. The designed fibrous battery demonstrates a high capacity of 0.85 mAh cm−1 and it can retain 90% (77.4%) of the initial capacity after 250 cycles under current density of 0.5 (5) mA cm−1. Additionally, the battery can maintain its performance under various deformations and a four-battery set is employed as the power source for LED patterns and wearable sensors. This work provides a rational way to design advanced gel electrolytes for high-performance flexible batteries.

Double-layered phase change materials featuring high photothermal conversion for stable thermoelectric power generation

Organic solid-liquid phase change materials have attracted great attention in the field of photothermal conversion and energy storage due to their advantages such as high latent heat, low subcooling, stable chemical properties, and constant temperature during the phase change process. However, preparing organic composite phase change materials (CPCMs) with multiple desirable properties such as good shape stability, high thermal conductivity, high enthalpy, and excellent photothermal conversion efficiency, remains a challenge. Herein, using a rapid melt blending of expanded graphite (EG) into lauric acid (LA) and cold pressing technique, we constructed double-layered and shape-stabilized D-LA/EG composites. The upper layer consists of 20 wt% EG and 80 wt% LA, while the lower layer 6 wt% EG and 94 wt% LA. It was found that the prepared D-LA/EG exhibited good shape stability, high thermal conductivity, high enthalpy, and excellent photothermal conversion efficiency. More interestingly, when applied as a heat source for an all-solid-state thermoelectric generator in a photo-thermal-electric conversion system, a stable output voltage of 315 mV is generated after the light is ceased, which is attributed to the release of the heat stored in the CPCMs. This work provides a simple and economical strategy to synthesize and balance the above four properties CPCMs, which has potential applications in photo-thermal-electric conversion and solar energy utilization.

Chitosan based aerogel fibers for piezoelectric and moisture electric energy harvesting

Taking advantages of renewable resourced materials in the preparation of multifunctional aerogel fibers which integrate thermal insulation, piezoelectric and moisture electric generation could be a promising way of relieving pressure on both energy loss and generation. A series of chitosan-konjac glucomannan (CS-KGM) aerogel fibers was obtained by means of wet-spinning method followed by freeze-drying. The CS-KGM aerogel fibers with submicron porous morphology exhibit excellent thermal insulation performance. Single layer of CS-KGM aerogel fiber with only a thickness of 0.6 mm shows a thermal insulation temperature difference of 23 °C. A stable piezoelectric output voltage of 0.35 V can be generated from a single CS-KGM aerogel fiber during a 500 press-release cycle attributing to the intrinsic piezoelectricity of CS and the porous structure. Single aerogel fibers were coated with multi-walled carbon nanotubes as a way to prepare conductive aerogels. Meanwhile, the moisture electric output voltage can be as high as 160 mV and last for >8 h at 60% relative humidity for CS-KGM single aerogel fiber assisted by a thin layer of carbon nanotube coating. Overall, CS-KGM aerogel fibers prepared in this work has good compatibility and potential applications in thermal management and energy harvesting from low density resource, which provides a new strategy for the preparation of sustainable and multifunctional wearable materials.

Analysis of Open Circuit Voltage MPPT Method with Analytical Analysis with Perturb and Observe (P&O) MPPT Method in PV Systems

This study conducts a comprehensive comparison between two prominent Maximum Power Point Tracking (MPPT) techniques employed in solar energy systems: the Perturb and Observe (P&O) method and the Analytical Solution Fractional Open Circuit Voltage (ASFOCV) method. To assess the effectiveness of these MPPT approaches, a simulation study was conducted using four SHARP NDQ295 model photovoltaic panels, configured as two panels in series and two in parallel. Both the P&O and ASFOCV MPPT methods were evaluated under various scenarios of radiation levels and temperature changes. The results unequivocally demonstrate the superior performance of the ASFOCV MPPT method over the P&O MPPT method. The ASFOCV method notably enhanced converter output power by up to 5% when compared to the P&O method, leading to more efficient energy production. Furthermore, the ASFOCV method exhibited rapid stabilization of output voltage during abrupt weather changes, outperforming the P&O method in this regard. This study underscores the potential of the ASFOCV MPPT method to enhance the efficiency of solar energy systems and its adaptability to fluctuating environmental conditions. Future research endeavors could focus on mitigating the ASFOCV method’s sensitivity to temperature variations and conducting real-world applications to further investigate its performance under practical circumstances.

Three-dimensional graphene-polypyrrole hydrogel as cathode for a bioelectric Mg-air battery

A bioelectric Mg-air battery offers a promising solution for powering implantable medical devices due to obvious merits such as easy miniaturization and ease of battery package. One of the key challenges in bioelectric battery is to seek air cathode materials with both satisfied electrocatalytic activity and good biocompatibility. 3D graphene macroassembly is the material of interest in metal air batteries as well as bioelectronics. For further performance enhancement, it is essential to incorporate other materials with better electrocatalytic performance into graphene matrix. Polypyrrole (PPy) has been intensively implemented in biomedical applications and energy storage for its biocompatibility and versatile properties including inherent electrocatalytic activity. In this work, a graphene-PPy composite was prepared based on a paper-like graphene hydrogel scaffold via facile interfacial gelation, and followed by PPy electrodeposition. The obtained G-PPy gel exhibited excellent performance in a Mg-air bioelectric battery, with stable voltage output of 1.15 V and 13.6 mAh cm−2 at 200 μA cm−2.

Research on the output voltage control of the Dual active bridge converter

in order to make the dual active bridge DC / DC converter output voltage stability, for the single shift phase control mode load disturbance, the input voltage disturbance affect the output voltage, puts forward a closed loop based on MATLAB self-regulation control, the control for a certain range of disturbance to maintain the output voltage stability effect is particularly obvious. This paper mainly introduces the working principle of DAB converter under single-shift phase modulation (SPS) and analyzes the topological structure of the circuit. Finally, the simulation model of the converter closed-loop control system is built on the simulink platform in Matlab, and the PID parameters are determined by using the self-regulation function to realize the pressure stabilizing output.

Layered Ferroelectric NbOI2 Flakes Toward In‐Plane Anisotropic Self‐Powered Sensing

2D ferroelectric materials have attracted much interest due to their potential for developing flexible self‐powered nanogenerators. Niobium oxide diiodide (NbOI2) has in‐plane anisotropy of electrical properties and large lateral piezoelectric coefficient, which makes it possess high‐performance and unique behavior in flexible sensing. In this work, multidirectional piezoelectric nanogenerator (PENG) devices using NbOI2 flake are fabricated and excellent energy harvesting and sensing capabilities are found. Specifically, the NbOI2‐based PENG can exhibit a long‐time stable voltage output of 215 mV at a large strain of 1.1%. More importantly, the periodic output signal pattern of the twelve‐electrode NbOI2‐based PENG in six directions is investigated, and this anisotropy provides the possibility of achieving simultaneous signal harvesting in multiple directions. This work broadens the scope of applications of 2D materials in nano‐energy and provides new ideas and insights for further exploration of nano‐energy and smart wearable nano‐electronic devices.

Spider Silk-Inspired Binder Design for Flexible Lithium-Ion Battery with High Durability.

The development of flexible lithium-ion batteries (LIBs) imposes demands on energy density and high mechanical durability simultaneously. Due to the limited deformability of electrodes, as well as the flat and smooth surface of the metal current collectors, stable/durable/reliable contact between electrode materials and the current collectors remains a challenge, in particular, for electrodes with high loading mass and heavily deformed batteries. Binders play an essential role in binding particles of electrode materials and adhering them to current collectors. Herein, inspired by spider silk, a binder for flexible LIBs is developed, which equips a cross-linked supramolecular poly(urethane-urea) to the polyacrylic acid. The binder imparts super high elastic restorability originating from the meticulously engineered hydrogen-bonding segments as well as extraordinary adhesion. The developed binder provides excellent flexibility and intact electrode morphologies without disintegration even when the electrode is largely deformed, enabling a stable cycling and voltage output even when the batteries are put under tough dynamic deformation tests. The flexible LIBs exhibit a high energy density of 420WhL-1 , which is remarkably higher than reported numbers. The unique binder design is greatly promising and offers a valuable material solution for LIBs with high-loading mass and flexible designs.

A novel control scheme for automatic voltage regulator using novel modified artificial rabbits optimizer

Automatic voltage regulators (AVRs) are essential components in electrical systems to maintain stable voltage output, ensuring optimal performance and equipment protection. The effectiveness of AVRs rely on key parameters such as voltage regulation, response time, stability, and efficiency. Integrating controllers with AVRs offers centralized monitoring and regulation, enhancing voltage output efficiency. This study therefore first discusses various controller types which showcase distinctive capabilities based on their tuning strategies and then introduces an intelligent optimization approach using fractional-order proportional-integral-derivative with double derivative (FOPIDD2) controller tailored for AVRs. The study adopts the artificial rabbits optimization (ARO) algorithm, fortified with an adaptive local search (ALS) mechanism and experience-based perturbed learning (EPL) strategy. The modified version (m-ARO) enhances solution diversity and navigational efficacy, resulting in improved optimization quality. The study's core objective is to demonstrate the superior performance of the m-ARO-based FOPIDD2 controller in addressing the multifaceted challenges of AVR control, outperforming conventional techniques in stability, speed of response, robustness, and efficiency. To validate the method's efficacy, a comparative analysis is conducted using existing controllers with different tuning algorithms. Results indicate that the proposed m-ARO-based FOPIDD2 controller achieves superior performance metrics, demonstrating its capability. The study also includes a wider perspective by considering nineteen different controllers, reported in the literature, for comprehensive comparison. Notably, the proposed method exhibits the best stability, further affirming its effectiveness.

Oscillator design for high efficiency DC-DC of micro direct methanol fuel cell

This paper develops a novel oscillator with wide output frequency range, continuous frequency adoption, anti-electromagnetic interference (EMI), and high precision in order to achieve the high energy conversion efficiency of DC-DC for micro direct methanol fuel cell (μDMFC). The oscillator employs the state of art including frequency jitter, slope compensation, and digital trimming to perform the load mode control and detection module, thus linearly adjusting the operating frequency and modulation according to the load. Based on the 0.18 μm microelectronics process, the transient output of the presented oscillator during continuously turning on exports a stable voltage square wave. The jitter frequency ranges only about −1.66% to +4.3% of the base frequency. Moreover, the oscillator can adjust the typical output frequency linearly from 100 kHz to 1 MHz continuously based on the light or heavy load state. The oscillator yields stable performance under EMI with the jittering rate ranges from −31.82% to 36.2%. The quantitative results validates the wide frequency range, continuous frequency adoption, anti-EMI, and high precision of the oscillator. The oscillator solves the low energy conversion efficiency of the μDMFC DC-DC. The oscillator will achieve high energy conversion efficiency and stable output voltage of μDMFC for practical application.

DC-Bus Voltage Sensorless Control of an Active Rectifier with Modular Multilevel Converter

The modular multilevel converter (MMC) is recognized as one of the promising converters for the electrification of ships and railways. Among different energy conversion stages, the MMC-based rectifier should realize stable DC output voltage and accurate input current control. However, output DC-bus voltage sensors must be installed, which are costly and bulky. This paper presents a simple but effective control method for the MMC-based rectifier, removing the traditional output DC-bus voltage sensor. An accurate evaluation model of DC-bus voltage is developed as well as the implementing method. Meanwhile, a safe and fast pre-charging scheme is presented for the MMC-based rectifier without output voltage sensors. The fault-tolerant capability of the proposed method when the failure of the output DC-bus voltage sensor occurs is examined. Simulated and testing results demonstrate that the proposed method presents not only excellent steady-state and dynamic performance but also strong fault-tolerant capability. The proposed evaluation model for DC-bus voltage has a high accuracy with an error of less than 1%. Besides, the pre-charging time is less than 0.5 s using the proposed sensorless control.

A new fast PWM modulation strategy for power electric converter based on finite set state machine theory

The finite set state machine theory belongs to the field of computer science. It is used to model and create multitasking systems. The control and modulation system for power electronics converters is a multitasking system as well. To increase the control speed without being constrained by the triangular wave module, the finite set state machine theory can be applied to converter modulation. In this paper, a modulation technique for finite state machines was proposed. This strategy fully uses the relationship between the affective state and converter switch states. Then, the structure of the modulation modular is presented in detail. This paper has analyzed the mathematical model of the finite set state machine modular. Finally, finite set state machine theory is used to Boost converter modulation modular to control the output voltage stability. Additionally, the effectiveness of the modulation strategy is validated by the experimental results.

Enhanced quadratic DC–DC boost converters with super‐wide voltage gain ranges and ultra‐low voltage stress for renewable energy systems

AbstractAs the promising and ideal clean energies, wind and solar energy systems are in desperate need of high‐performance DC–DC converters to realize efficient and reliable energy transformation. Conventional DC–DC converters for renewable energy systems will work at extreme duty cycles and affect the system efficiency and reliability owing to their limited voltage gains and high‐voltage stress. In this paper, by adopting the hybrid voltage multiplier cells, two enhanced quadratic boost converters (EQBCs) which are highly desirable for renewable energy applications are proposed and analyzed. The EQBCs possess super‐wide voltage gain ranges and ultra‐low voltage stress; therefore, small duty cycle conditions can be achieved and components with low‐rated voltages can be chosen to decrease system volumes and increase system efficiencies. Besides, the EQBCs possess continuous input currents, which can realize small input current ripples and avoid the serious effect of pulsating current on the input sources. What's more, stable output voltages and simple controller circuits are realized by the EQBCs because of the common grounded structures of the input terminal, the single active switch and the output terminal. Detailed principle analyses, parameter designs, performance comparisons and experimental prototypes are conducted to verify the characteristics and feasibilities of the EQBCs.

Research on power management circuit of magnetic field energy harvesting for wireless sensor

In order to solve the power supply problem of wireless sensors in the power cable environment, the changing magnetic field around the cable is used, and the open energy harvesting coil and power management circuit are used to supply power to the sensor. However, improving circuit applicability and output efficiency is the key. For this reason, through the circuit principle and simulation analysis, the basic model of the power management circuit is established, and the overvoltage protection and energy storage unit are designed for the special environment of the cable to solve the problem of circuit protection and energy supply dead zone. Then reduce the circuit loss according to the circuit topology design. Finally, an experimental platform is built to verify the output effect of the power management circuit. The voltage induced by the magnetic induction power acquisition module can obtain a stable and reliable output voltage through the power management circuit, which can realize the self-sufficiency of the power supply of the wireless sensor.

Research on Bidirectional DC-DC Converters in Distributed Electric Propulsion Systems

This paper investigates bidirectional DC-DC converters in distributed electric propulsion systems, focusing on the dual active bridge (DAB) converter. To minimize voltage fluctuations in aircraft operating under complex conditions, a virtual voltage compensation control strategy based on active disturbance rejection (ADR-VVCC) is presented. The presented control strategy is grounded on the working characteristics under single-phase-shift (SPS) and introduces a virtual voltage to compensate for voltage fluctuations and degraded dynamic performance caused by the inherent uncertainty of converter parameters and power losses during the energy transfer process. The active disturbance rejection control is incorporated to replace traditional PI control, thereby enhancing the converter’s dynamic performance. Simulation outcomes demonstrate that the presented control strategy effectively improves the converter’s dynamic performance and maintains output voltage stability.

A Control Method for Output Voltage Stability of Proton Exchange Membrane Fuel Cells

The widely used PEMFC (Proton Exchange Membrane Fuel Cell) analysis found that when the REMFC load is changed, its instantaneous output voltage fluctuates, and it causes voltage loss. The main reason is that it is activated by activation. The characteristics of the three-proton exchange membrane fuel battery characteristics of Ohm overvoltage and thickness cause voltage loss. By using the corresponding empirical formula in the Matlab / Simulink environment, the study designs the PID and the Fuzzy PID Controllers. After the established dynamic model of PEMFC, it controls the hydrogen supply module, changes the ratio of hydrogen and oxygen input, and indirectly controls the output voltage. Through experiments, it was found that Fuzzy PID Controller can achieve faster and smoother voltage stability than an ordinary PID Controller and less overshoot when load change, The controller can control the system voltage to reach a set point and to stabilize the supply voltage for the load.

OPERATING MODES OF MICRO-HYDROELECTRIC POWER PLANT WITH OUTPUT VOLTAGE STABILIZATION USING INVERTER CONTROL

Link for citation: Lukutin B.B., Shandarova E.B., Popov M. M. Operating modes of micro-hydroelectric power plant with output voltage stabilization using inverter control. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 51-58. In Rus. The relevance. The use of Russia's hydroelectric potential for electricity generation is one of the cleanest and environmentally friendly methods as it does not result in the emission of harmful substances and carbon dioxide into the atmosphere. Moreover, it is a reliable and efficient source of energy as water is a constant source of energy. Hydro turbines are used to convert the energy of water flow into electrical energy, which effectively ensures more reliable and stable production capacity for hydroelectric installations. However, micro-hydroelectric power plants have some drawbacks related to difficulties in ensuring the high quality of produced electricity of autonomous power supply systems. This is due to the fact that the load on the autonomous power supply system can vary not only in magnitude but also in nature, which makes it difficult to maintain a stable level of electricity production. The main goal of the research is to determine the ranges of variation of the output electrical parameters of a non-regulated hydrogenerator operating as part of an inverter-based micro-hydroelectric power station for rural domestic consumers. Additionally, the task is to formulate requirements for the hydrogenerator and power conversion devices in static and dynamic operating modes of the autonomous power supply system. Object: inverter-based micro-hydroelectric power station. Methods: simulation modeling, and programming in Matlab Simulink. Results. A simulation model of an electric power supply system with an inverter microelectric power station was developed. The structure of microelectric power station is proposed, as well as the ranges of voltage changes of the microelectric power station generator are obtained.

Non-fragile guaranteed cost control of microbial fuel cells

A microbial fuel cell (MFC), which is a new type of energy source, utilises electrogenic bacteria in sewage or soil to convert chemical energy into electrical energy. MFCs typically require an external controller to provide a stable output voltage to the external load. This study develops a non-fragile guaranteed cost (NFGC) controller to suppress the interference of the controller of an MFC and ensure that the quadratic cost function of the system satisfies certain performance indexes. First, for the convenience of controller design, a Takagi–Sugeno fuzzy model is established to approximate a single-chamber single-population MFC model. Subsequently, the linear matrix inequality method is used to design the NFGC controller. This control scheme can reduce the influence of controller disturbances on the system and ensure asymptotic stability of the closed-loop system under the specified upper bound of the provided cost function. The simulation results demonstrate that the developed control method has a shorter adjustment time and smaller steady-state error than traditional control methods such as sliding mode control (SMC), backstepping control, and fuzzy SMC

A novel PFM/PWM hybrid modulated single‐stage FSBB‐LLC AC‐DC converter

SummaryBy integrating the four switch buck–boost (FSBB) PFC and full‐bridge LLC resonant converter, a novel single‐stage FSBB‐LLC AC‐DC converter is proposed. Meanwhile, the corresponding PFM/PWM hybrid modulation is put forward. The proposed solution employs a dual‐loop feedback control strategy based on PFM/PWM hybrid modulation to obtain the desired bus voltage and stable output voltage. The bus voltage feedback loop is mainly used to smoothly determine the boost or buck–boost mode of FSBB PFC cell for regulating the bus voltage; the output voltage feedback loop is in charge of stabilizing the output voltage by adjusting the switching frequency or phase shifting angle. Furthermore, an optimal parameter design based on power balance principle is also derived. The experimental results of an 85 ~ 300 V input, 12V/25A output prototype demonstrate that (1) low and narrow bus voltage of 240 ~ 340 V is achieved under the entire input and output condition; (2) the LLC cell operates at DCX mode over the whole load range as the input voltage exceeds 120 V; (3) the output voltage is well regulated even under the no‐load condition; (4) ZVS feature for the shared switches is still maintained; and (5) a peak efficiency of 90.9% and PF values above 0.987 are achieved.

Suppression of voltage gain fluctuation in LLC Resonant Converter Based on chaotic spread spectrum

In order to realize the voltage stable output of the LLC resonant converter under different loads, a voltage gain fluctuation suppression technology of the LLC resonant converter based on a chaotic spread spectrum is proposed. The gain fluctuation electromagnetic interference signal is eliminated by the Chua’s circuit; The rated voltage value is discretized, and the target network and the evaluation network are used to form a deep Q network, with the multi-threshold judgment method and the variable step method respectively completed the gain fluctuation suppression target under different working conditions. The experimental results show that the proposed technology can achieve stable voltage output in both dynamic and steady-state conditions, with good gain fluctuation suppression effect and strong timeliness. It provides data reference for the rational application of the LLC resonant converter.