Micro Power Supply Research Articles

Ultra Short-term Load Optimal Dispatching Method for Micro Grid Considering Demand Side Response

With the development of the economy, the electricity demand is also increasing. However, the traditional micropower supply bears the problems of excessive load growth and unstable voltage. Therefore, this paper takes power generation as the research object. First, the principle of output optimization based on schedulability, reserve capacity, and intermittent operation frequency of units is analyzed. Then, the relationship between the optimal solution and the minimum power consumption time is calculated by establishing a mathematical model to solve the algorithm, and the difference between the two results is compared. Finally, the power system is simulated on Matlab software, and the method and effect are verified by numerical simulation. The simulation results show that with the same microgrid power configuration, there is a 3.5% load transfer at time-sharing prices and a 6.4% load transfer at real-time prices through price-based demand response. The optimization objective of demand response, namely the cumulative sum of the difference between new energy power generation and load, is 15312 kW · h per year when the fixed price is implemented, 54134 kW · h is for the time of use price, and 451645 kW · h is for real-time price. The response effect of real-time price is optimal.

Stretchable π-conjugated polymer electrets for mechanoelectric generators

Electrets are materials that retain quasi-permanent electric charges and are attracting attention as key components of batteryless micropower supplies. A chemical structure that facilitates ionization and that can stabilize these charges, such as a π-conjugated system, is expected to increase the charge density compared with that of conventional insulating polymers. Here, we report a mechanoelectric generator (MEG) (vibrational energy harvester) that uses alkylated π-conjugated polymers (Alk-CPs), which can be monopolarized either into positive or negative mode electrets. With the attachment of insulating, bulky, yet flexible alkyl side chains to the π-conjugated backbone, the poled Alk-CPs showed long charge lifetime suitable for MEGs. The elastic modulus of the electret was adjusted to approximately match that of the stretchable polyurethane substrate by blending two miscible Alk-CPs with different elastic moduli, producing a laminated film that could be stretched up to 300%. The MEG presented showed conformability when applied to a deformable object.

Study on Economic Dispatch of the Combined Cooling Heating and Power Microgrid Based on Improved Sparrow Search Algorithm

The reasonable and efficient use of the abundant biomass resources in rural areas has not been realized. Therefore, the concept of a combined cooling, heating, and power (CCHP) microgrid system, considering biomass pyrolysis and gasification, has been developed by researchers. A biomass gasification device can fully use biomass resources and can play a role in absorbing wind energy. Meanwhile, in order to minimize the operating cost of each micropower supply unit, as well as the environmental pollution costs, researchers have also established an optimal scheduling model for CCHP microgrids, which uses the sparrow search algorithm. In this paper, we have improved upon the traditional sparrow algorithm to solve the problems of its uneven population distribution, poor global search ability, and the risk of falling into local optima, through the development of the random walk sparrow search algorithm (RSSA). First, a sinusoidal chaotic map is used to generate the early-generation sparrow population with a uniform distribution in space. Second, in this study we add a sharing factor to the discoverer’s optimization process to enhance information sharing and the global research capability among individuals in this field. Finally, a random walk strategy is used to form new participants to improve the algorithm’s skill in locally searching for optimal locations. Taking the CCHP microgrid with grid-connected action as a case study, we concluded that compared with the optimization outcomes of the SSA, the total costs incurred by RSSA in summer and winter were reduced by 2.2% and 3.1%, respectively. Compared with the optimization findings for the chaotic SSA algorithm, the total costs incurred using the RSSA algorithm under typical summer and winter days were reduced by 0.14% and 0.13%, respectively. The productiveness of the RSSA algorithm for solving the CCHP microgrid economic dispatch issues has thus been verified.

Elimination of Fuel Crossover in a Single-Flow Microfluidic Fuel Cell with a Selective Catalytic Cathode

Membraneless microfluidic fuel cells (MMFCs) remove the physical membrane in conventional fuel cells and are considered one of the promising micropower supplies for portable electronic devices. However, a co-laminar flow pattern should be maintained to avoid fuel crossover, which goes against the integration of the cell and its applicability. Herein, we adopt activated carbon (AC) as the cathode catalyst to trigger the oxygen reduction reaction (ORR) and construct a novel single-flow MMFC (SF-MMFC). Benefitting from the selective catalytic property, the unfavorable fuel-crossover issue is successfully avoided, and device construction is extremely simplified. One single reactant solution containing both fuel and electrolyte can successfully maintain SF-MMFC stable operation. The device delivers a volumetric power density of 218.6 mW cm–3; nevertheless, the ORR catalytic performance for AC powders is poorer than that of commercial Pt/C cathode. More importantly, the capital power production per unit cathode cost is 200 W $c–1. The utilization of catalyst with selective catalytic performance can accelerate the application potential of MMFC technology in powering portable electronic devices.

Recent Advances in High-Performance Microbatteries: Construction, Application, and Perspective.

High-performance miniaturized energy storage devices have developed rapidly in recent years. Different from conventional energy storage devices, microbatteries assume the main responsibility for micropower supply, functionalization, and characterization platforms. Evolving from the essential goals for battery design of high power density, high energy density, and long lifetime, further practical demands for microbatteries (MBs) have been raised for the microfabrication technique and device design. Numerous studies have generally focused on specific aspects of the microelectrode structures or certain microfabrication techniques, while the connection from techniques to functional applications is rarely involved. This Review generally fills such blanks from an application-oriented perspective. First, some basic micromachining techniques with different compatible features are summarized. Afterward, device designs including diversified battery reaction types, configuration, and assembly are highlighted, as well as microbatteries serving powering resources or further complicated functional systems. Finally, through providing the overall design concept based on requirements in application, this Review offers innovative insights for further development of microbatteries.

Research on piezoelectric vibration energy harvester with variable section circular beam

In order to reduce the natural frequency of the piezoelectric vibration energy harvester, improve performance of the piezoelectric vibration energy harvester, and meet the requirements of energy acquisition in the low-frequency vibration environment, a variable-section circular piezoelectric vibration energy harvester is presented. The dynamic model and electromechanical coupling model of variable-section circular piezoelectric vibration energy harvester are established. The main factors affecting the output performance of piezoelectric vibration energy harvester are analyzed. The structure parameters of piezoelectric vibration energy harvester are optimized by orthogonal experiment. An experimental platform is built to test output voltage and output power of piezoelectric vibration energy harvester. The experimental results show that when the number of energy harvester is 4 and the external load is 180KΩ, the parallel output power can reach 0.213mW, which can meet the requirements of micro-power device power supply.

Research on Optimized Configuration of Micro-Power Supply for AC-DC Hybrid Microgrid Based on Particle Swarm Optimization Dynamic

Optimal configuration of the micro power supply is the basis for ensuring stable and economic operation of the microgrid. In this paper, a micro-grid optimal configuration model of microgrid based on particle swarm optimization (PSO) is proposed. It is studied from the aspects of economy and reliability, and optimized by weight coefficient method to obtain the best micro-power supply under various conditions capacity. In this paper, the micro-power supply capacity under the island operation mode is studied, and the model is solved by particle swarm optimization. The simulation results show the feasibility and correctness of the model and the particle swarm optimization algorithm, and improve the economics and reliability of the microgrid.

Implanted Battery-Free Direct-Current Micro-Power Supply from in Vivo Breath Energy Harvesting.

In vivo biomechanical energy harvesting by implanted nanogenerators (i-NGs) is promising for self-powered implantable medical devices (IMDs). One critical challenge to reach practical applications is the requirement of continuous direct-current (dc) output, while the low-frequency body activities typically generate discrete electrical pulses. Here, we developed an ultrastretchable micrograting i-NG system that could function as a battery-free dc micro-power supply. Packaged by a soft silicone elastomer with a cavity design, the i-NG exhibited an ultralow Young's modulus of ∼45 kPa and a high biocompatibility to soft biological tissues. The i-NG was implanted inside the abdominal cavity of Sprague Dawley adult rats and directly converted the slow diaphragm movement during normal respiration into a high-frequency alternative current electrical output, which was readily transmitted into a continuous ∼2.2 V dc output after being integrated with a basic electrical circuit. A light-emitting diode was constantly operated by the breath-driven i-NG without the aid of any battery component. This solely biomechanical energy-driven dc micro-power supply offers a promising solution for the development of self-powered IMDs.

An Integrated 3-mW 120/230-V AC Mains Micropower Supply

The maintenance issue of batteries and the limited power level of energy harvesting is addressed by the presented integrated micropower supply. Connected to the 120/230- $\text {V}_{\text {RMS}}$ mains, it provides a 3.3-V ac output voltage, suitable for applications such as the Internet-of-Things and smart homes. The micropower supply consists of a fully integrated ac–dc and dc–dc converter with one external low-voltage surface mount device buffer capacitor, resulting in an extremely compact size. Fabricated in a low-cost 0.35- $\mu \text {m}~700$ -V complimentary metal-oxide-semiconductor technology, it covers a die size of 7.7 mm2. The ac–dc converter is a direct coupled, full-wave rectifier with a subsequent series regulator. The dc–dc stage is a fully integrated capacitive 4:1 converter with up to 17-V input and 47.4% peak efficiency. The power supply comprises several high-voltage control circuits including level shifters and various types of charge pumps (CPs). A source-supplied CP is utilized that supports a varying switching node potential. The overall losses are discussed and optimized, including flying capacitor bottom-plate losses. The power supply achieves an output power of 3 mW, resulting in a power density of 390 $\mu \text {W}/ \text {mm}^{2}$ . This exceeds prior art by a factor of 11.

Enzymes Confinement in CNT Doped Carbon Microstructures Electrodes (CNT-CME) for Miniaturized Enzyme Biofuel Cell Application

Fast development of biomedical technology has led us to the invention and use of implantable medical devices to be utilized for direct monitoring of human health. In general, batteries is used as the main micropower supply of these implanted devices, however it has some drawbacks as it has to be replenished in due time. One of the promising continuous energy supplies to replace the use of batteries is enzyme biofuel cell (EBFC) which harvests electrical energy from the oxidation-reduction reactions as it generates electricity by glucose oxidation and oxygen reduction by the anode and cathode enzymes respectively; in which two of its main substrate are abundant and essential components in human physiological fluid. EBFC is expected to be minimal in size but still concerning to have maximized performance during operation including; high electrode potential range, current and power densities which dependent to the stability of the enzyme used and enzyme environment construction. In order to achieve long operation of EBFC, it is necessary to be assured that enzyme will not be denatured due to external potent factor such as shear stress, especially if EBFC is employed as micro-power supply of implanted devices in human in which the blood velocity will depend on the diameter of blood vessel as implantation site. One of the modest methods to protect immobilized enzyme from the shear stress is by using polymer such as Nafion to form physical entrapment layer. However, there is high possibility that Nafion as polymer will be degraded under shear stress leading to leaching of enzyme during long operation. Previous studies showed that encapsulated protein in porous materials, or immobilized inside layer by layer material showed more stability due to less exposure of the external stress. The use of mesoporous material such as sol-gels and entrapment in mesoporous silica have proven to increase the enzyme stability, however this materials are lack of conductivity which is not suitable for bioelectronics application. Due to the necessity of electrical communication, another study was employing conducting material such as Si wafer with micro culverts as enzyme protection platform which enhance the electron transfer between enzyme-electrodes material . The success of enzyme immobilization also depends on its carrier used for particular application. The platform for enzyme immobilization should have high capacity as enzyme anchoring sites, chemically stable, and having the structural ability to prolong enzyme stability. The combination of nanostructures with enzyme immobilization will be a promising direction since it is possible to engineer enzyme environment to limit the effect of external forces as called enzyme-in-cage. Carbon as the most popular and widely studied as electrode materials due to its physical and electrochemical stability properties as inert material, low cost and easy to be functionalized and decorated. Carbon can be used for miniaturized electrode fabricated through nanolithography by pyrolizing photoresist, decompose co-composite, leaving only carbon in microstructured pattern. The use of photoresist to form carbon after pyrolysis step has the advantage due to its ability to be patterned by photolithography techniques which is reproducible. The properties of pyrolized electrodes are comparable than glassy carbon electrode (GCE) which has similar electrochemical properties such as low background current as the effect of low capacitance Further advancement for this system is the integration of CNT which has high surface area, excellent conductivity due to its sp2carbon hybridization along its wall. In order to prevent any proximity effect of CNT-pyrolyzed carbon electrode, CNT was grown directly in carbon post in which the catalyst of CNT growth was deposited through electrostatic spray deposition (ESD). Grown CNT on pyrolyzed carbon is expected to keep high structural stability. In this study we elaborated the fabrication and application of CNT doped carbon microstructures (CNT-CME) as platform for enzyme confinement and immobilization. Thus eventually this method then applied to immobilize the FAD-dependent glucose dehydrogenase (FADGDH) α-subunit with menadione as mediator (FADGDH/menadione) system which has proven to have better performance as anode for biofuel cell application as its native character of low Km value. The parameter such as K mof free and immobilized enzyme, current and power densities of the EBFC were also tested. Figure 1

Flexible all-solid-state supercapacitors based on polyaniline orderly nanotubes array

Flexible all-solid-state supercapacitors are crucial to meet the growing needs for portable electronic devices such as foldable phones and wearable electronics. As promising candidates for pseudocapacitor electrode materials, polyaniline (PANI) orderly nanotube arrays are prepared via a simple template electrodeposition method. The structures of the final product were characterized using various characterization techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The obtained PANI nanotube film could be directly used as a flexible all-solid-state supercapacitor electrode. Electrochemical results show that the areal capacitance of a PANI nanotube-based supercapacitor with the deposition cycle number of 100 can achieve a maximum areal capacitance of 237.5 mF cm-2 at a scan rate of 10 mV s-1 and maximum energy density of 24.31 mW h cm-2 at a power density of 2.74 mW cm-2. In addition, the prepared supercapacitor exhibits excellent flexibility under different bending conditions. It retains 95.2% of its initial capacitance value after 2000 cycles at a current density of 1.0 mA cm-1, which displays its superior cycling stability. Moreover, the prepared flexible all-solid-state supercapacitor can power a light-emitting-diode (LED), which meets the practical applications of micropower supplies.

Research on Efficiency of Solar Cell Integrated with Energy Management Circuitry on Chip

In photoelectric micro-power supply integrated on chip, the conversion efficiency of solar cell was lower compared with canonical solar cell. In order to improve the conversion efficiency of the solar cell, three technologies (fabricating back surface field, fabricating surfaces texture and reflector) were adopted in integrated process of photoelectric micro-power supply on chip. The relevant theory of the three technologies was introduced. The optimum schedule of the photoelectric micro-power supply integrated on SOI wafer was proposed. The conversion efficiency of solar cells was analyzed by simulation tools (PC1D). The results prove the conversion efficiency of solar cells was improved from 9. 34% to 13.3%.

A High Efficiency Solar PV Micro-Power Supply Integrated with Wireless Sensor Nodes

In the wireless sensor nodes integrated with the solar PV micro-power supply, the solar energy conversion efficiency and utilization efficiency directly determine working life and stability of the wireless sensor nodes. Thus, a novel solar PV micro-power supply is designed which four solar cell arrays with same open voltage are designed and they are placed in top and three sides of the wireless sensor nodes. Simultaneous, the optimal voltage control technology is used to control work voltage of four solar cell arrays in the design. In addition, the prototype of wireless sensor node integrated with the solar PV micro-power supply is done. Moreover, the working characteristics of the prototype are tested in natural condition. The working voltages of four solar cell arrays are controlled in range of optimal voltage, and the solar cell arrays have high conversion efficiency. The output energy of system is increased about 50% by adding side solar cell arrays.

The impact of monochromatic blue and red LED light upon performance of photo microbial fuel cells (PMFCs) using Chlamydomonas reinhardtii transformation F5 as biocatalyst

Photosynthetic microbial fuel cells (PMFCs) are devices that convert chemical energy into the form of electricity through the catalytic activity of photosynthetic microorganisms. Power densities produced by the photosynthetic microalgae are greatly dependant on light sources and light intensities because these two factors can affect the chlorophyll formation, photosynthesis processes and stomata opening in the microalgae cells. In the present study, Chlamydomonas reinhardtii transformation F5 was used as biocatalyst in photo microbial fuel cells (PMFCs) and were illuminated with monochromatic blue and red LED lights at various light intensities (100, 300, 600 and 900lx), respectively. The kinetic analysis was successfully employed to describe the intracellular and extracellular electron transfer mechanism of the cells. The results demonstrate that the performance of PMFCs increased in terms of maximum power density and exchange current density (io) with the tendency of decreasing in internal resistance (Rint) and over potential (η) values as increasing monochromatic blue and red LED light intensities. However the PMFCs performed better under red LED light as compared to operating under blue LED light. The maximum power density can reach 12.947mWm−2, which could be a potential micro-power supply.

Research of Solar Photoelectric Micro-Power Supply on Chip

In order to reduce volume of MEMS wireless sensor with solar photoelectric micro-power supply, the integration scheme of solar photoelectric micro-power supply on chip is proposed in the paper. The scheme is consisted of seven main process steps, and has higher process compatibility. The characteristics of the integrated devices of the solar photoelectric micro-power supply are analyzed by using the semiconductor theory. The results show the device characteristics meet the requirement of the solar photoelectric micro-power supply. Moreover, the technology improving conversion efficiency of solar cells on chip is proposed by use of the back surfaces field (BSF). The conversion efficiency of solar cells reached 13.4%

Design of solar photovoltaic micro-power supply for application of wireless sensor nodes in complex illumination environments

The advantages of the wireless sensor nodes, integrated with the solar photovoltaic (PV) micro-power supply, have been proved, and some design technologies of the solar PV micro-power supply have been proposed in the previous report. However, using the wireless sensor nodes integrated with the solar PV micro-power supply is limited in complex illumination conditions because of the low energy conversion efficiency of the solar PV micro-power supply. To enlarge application environment of the wireless sensor nodes integrated with the solar PV micro-power supply, it is crucial to enhance the energy conversion efficiency of the solar PV micro-power supply in complex illumination conditions. In the study, a novel solar PV micro-power supply using the optimal voltage control technique and the solar cells array in series–parallel has been designed. Moreover, the wireless sensor node integrated with the solar PV micro-power supply has been achieved. In different illumination environments, the performances of the solar PV micro-power supply have been tested. According to test results, the solar PV micro-power supply can keep high output conversion efficiency and the output stability in complex illumination conditions.

Modeling of Photoelectric Micro-Power Supply for Wireless Sensor Nodes

For the wireless sensor node integrated with photoelectric micro-power supply, the photoelectric micro-power supply (PMPS) determines their life time, stability and adaptability to the local environment. The design of PMPS involves the study related to incident light power, photoelectric conversion efficiency of solar cells, characterization of storage devices, energy management and operation state control of sensor nodes, etc. The design process of PMPS is complicated. In this study, in order to simplify the design process of the PMPS and optimize it, we analyze all of the power parameters for the PMPS for sensor nodes. According to the energy transmission modes of PMPS for sensor nodes, the design model of PMPS is established. The rationality of PMPS is verified by experiments and simulations based on wireless sensor node (Ginze3).

Study on structure optimization of a piezoelectric cantilever with a proof mass for vibration-powered energy harvesting system

The study of micropower supply has become a key issue in the development of wireless sensor networks using microelectromechanical system technology. Vibration-powered energy harvesting system is considered as a good source for generating micropower. A general layout of a vibration energy harvesting system based on a sandwiched (PZT–Si–PZT) rectangle cantilever with a nickel proof mass was proposed. For the optimization of the system, formula of the voltage and power output based upon an equivalent circuit of piezoelectric layer and ac-dc converter was deduced. For the vibration harvesting structure, lower resonance frequencies are usually preferred. In order to find the relationship of the cantilever length and proof mass on the resonance frequencies of the energy harvesting structure, computations using Microsoft Excel software were conducted. The results show that it would be advisable not to increase the cantilever length only in order to get lower resonance frequency. However, the resonance frequency of the structure can be reduced dramatically by the accession of a proof mass with reasonable weight, so that the whole structure can be optimized to fit its application in natural environment. This study provides some basic considerations for the design of piezoelectric-based vibration energy harvesting system for converting ambient vibrational energy into electricity.

마이크로 압전변압기 제작 및 전기-기계적 특성 분석

For the applications which need a micro-power supply such as thin and flat displays, micro-robot, and micro-system, it is especially necessary to integrate the passive components because they typically need more than 2/3 of the space of the conventional circuit. Therefore, we have designed and fabricated a novel piezoelectric micro transformer using the PZT thin film and MEMS technologies for application to the energy supply device of the micro-systems. The dimensions of the micro-transformer is 1000 ㎛ × 400 ㎛ × 4.8 ㎛ (length × width × thickness). The dynamic displacement of around 9.2 ± 0.064 ㎛ was observed at 10 V. The dynamic displacement varied almost linearly with applied voltage. The average voltage gain (step-up ratio) was approximately 2.13 at the resonant frequency (Fr=8.006 ㎑) and load resistance (R<SUB>L</SUB>) of 1 MΩ.

Prototype silicon micropower supply for sensors

Miniature, remote, autonomous sensors generally have a relatively large power supply compared to the size of the sensor and sensor conditioning electronic circuitry. An integrated micropower supply made in a silicon wafer offers the prospect of shrinking the power supply size down to the size of the sensor and conditioning circuitry. In this paper, we describe a prototype silicon micropower supply comprising a nickel-zinc microbattery integrated in a silicon wafer interfaced to a miniature silicon solar array via an adaptable charge controller that can optimally supply charging current from the miniature solar array to the microbattery. Details of each of the subsystems are described together with test results on a multichip, hybrid implementation of an all-silicon, miniature power supply.