Low Power Loads Research Articles

Linear-rotary direct drive for multi-functional machine tools

By combining linear and rotary movement in one single drive, the overall dynamics of machine axes can be enhanced, and the installation space can be reduced. Existing concepts for linear-rotary drives either have low power density or load capacity, and the installation space of the guideways are not sufficient for applications in machine tools. Thus, this paper presents a novel linear-rotary direct drive for machine tools. The electromagnetic coupling between the linear and rotary direction is analyzed, and the control performance is evaluated. The developed drive is characterized by stiffness of up to 205 N/µm, acceleration dynamics of 3,100 mm/s2 in linear and 24,100 °/s2 in rotary direction, and fine positioning in 0.2 µm and 3.6″ steps.

High-Performance Power Converter for Charging Electric Vehicles

This paper presents the analysis, modeling, simulation and practical studies of resonant inverters with a voltage limitation on the resonant capacitor. The power circuits obtained in this way are characterized by the fact that the power consumption does not depend on the load changes, but is a function of the operating frequency, the value of the resonant capacitor and the supply voltage—these are the so-called inverters with energy dosing. Analytical dependences, simulations and experimental results were determined, which described the behavior of the studied power electronic devices. The obtained expressions for the inverter current in the different stages of the converter operation were the basis for the creation of the engineering methodology for their design and prototyping. Based on the derived basic ratios and characteristics, the capabilities of these devices for self-adaptation to the needs and changes of the load were demonstrated. A comparison of the characteristics of classical resonant inverters and those with energy dosing was made, thus demonstrating their qualities and advantages. The presented results display the properties of this class of circuits and the challenges to their effective application to find the optimal solution for the implementation of charging stations for different specific needs. On the other hand, the limitations in the use of these circuits were that no power was consumed from the power supply during the whole period, the lack of limitation of the maximum current through the transistors and the need for sufficient time to dissipate energy in the resonant inductor when working with high-resistance and low-power loads.

Numerical and experimental investigation of enhanced heat transfer radiator through air deflection used in fuel cell vehicles

Proton exchange membrane fuel cells are an ideal power source for modern energy vehicles owing to their high efficiency, fast response, and zero emission. Because of the low heat exchange temperature difference and high power load, the cooling system in internal combustion engine vehicles can no longer satisfy the heat dissipation demand of fuel cell vehicles (FCVs). Thus, the thermal management of FCVs must be improved, for which the compact radiator is a crucial component that discharges most of the waste heat outside the FCV. By inserting metal elbows into the airside of a compact radiator, we propose a novel structure aimed at promoting the thermal performance of a traditional compact radiator. The thermal and flow characteristics of the two types of radiators (traditional and optimised radiator) are compared, and the effect of the inserted windward bend structure is investigated numerically and experimentally. The Colburn j-factor and Fanning friction f-factor are calculated to evaluate the airside performance of the two radiators. The results indicate that the heat exchange is improved by 17.1%, 19.6%, 19.3%, and 22.5% accompanied with a modest increase in the pressure drop of 0.1%, 18%, 21%, and 18%, respectively, under four different operating conditions.

An improved genetic algorithm for determining the optimal operation strategy of thermal energy storage tank in combined heat and power units

The TES (thermal energy storage) tank has been widely used in CHP (combined heat and power) units to consume more renewable energy. In this paper, the hourly operation model has been established to solve the operation strategy problem of TES tank. The limitations of standard genetic algorithm used in the operation strategy of TES tank have been analyzed, then an improved genetic algorithm is proposed. At last, the improved genetic algorithm is used to optimize the operation strategy of TES tank by combining the characteristic day method. The results show that the improved genetic algorithm can enhance the local search ability and calculation speed obviously, and the calculation speed will be further improved after combining the characteristic day method. In order to obtain the maximum profit, the TES tank should store thermal energy at high minimum power load and release thermal energy at low minimum power load. In addition, the optimal capacity of TES tank in different months varies greatly during the period of thermal energy supply. The optimal capacity of TES tank should be the maximum value among all the months to ensure the thermal energy supply.

Intelligent controller based optimum load shedding for photovoltaic and wind energy integrated power systems

ABSTRACT Power generation by renewable energy sources plays a major role to meet the consumer demand. The proposed renewable energy sources, Photovoltaic (PV) and wind energy sources are integrated with power grid using Voltage Source Converter (VSC). The renewable energy sources have been simulated and evaluated under various operating conditions using MATLAB environment. The main objective of this research paper is to investigate the renewable energy system and its effectiveness in load shedding using fuzzy logic control algorithm. In this study, three type of load priority has been labelled, high priority, medium priority and low priority power load. The fuzzy controller will select the priority of the load, based on the availability of PV and wind power supply. The controller performance analysis under various operating conditions are evaluated by IEEE 1547 standards for proving the effectiveness of proposed control algorithm.

Words against injustices: A deep narrative analysis of energy cultures in poverty of Abuja, Mumbai and Rio de Janeiro

Slum rehabilitation housing (SRH) are critical transitional spaces in urban informality that has deep-rooted implications on poverty alleviation efforts. However, current literature reports systemic injustices in SRH on access to essential services, including energy injustices. This study investigated distributive injustices in the SRH across three cities, Abuja, Mumbai and Rio de Janeiro, developing ‘energy cultures’ narratives. It employed a computational social science methodology that used textual analysis, followed by a constructivist grounded theoretic approach to inform just policy design. The analysis was performed at two scales to identify and contrast injustices in the study areas. The result at an aggregated scale showed commonalities were around the poor design of the built environment, administrative lags of the utilities and high electricity bills. Case study-specific results showed that poverty penalties were linked with the energy cultures of each SRHs. In the Mumbai case, poverty penalties were associated with the aspirational purchase of household appliances due to move from slums to SRH. The Abuja case showed low power quality and load shedding frequently damaged appliances that increase the maintenance costs for the occupants. The Rio de Janeiro SRH case had injustices embedded through the adoption of inefficient appliances received as charity from higher-income households. Fuel stacking was also observed in the SRH that illustrated cultural identities associated with cooking energy. The conclusion was drawn to support just policy design by considering the socio-cultural context of the built environment, improving utility governance and promoting cleaner fuel mix at the household level.

Design and Techno-economic analysis of power generating unit from waste heat (Preheater and grate cooler) of cement factory in Ethiopia

Waste heat from industries, when are not captured, is useless and contributes to environmental pollution. There are many methods to recover the waste heat generated from local industries, but this present work was done on shell and tube type heat exchanger for waste heat recovery. Recapturing and reusing this waste heat by using waste heat recovery would simultaneously reduce energy prices and greenhouse gas emissions. This present work aims to design and techno-economic analysis of power generating unit from waste heat (preheater and grate cooler) of cement factory line 2 to avoid the problems that are caused due to the burning of fossil fuels and to ensure the environmental sustainability. This present work is design and techno-economic analysis of power generating unit consist of mixing chamber, electrostatic precipitator, shell and tube type heat exchanger, superheater, piping systems, steam turbine, surface condenser and feedwater pump as its main components. Several methods were used, including secondary data collection, system design, and system cost analysis. The factory's collected data was the temperature of waste heat from the grate cooler stack of 285℃ with the amount of 1.938 kg/kg of clinker and which leave the six cyclone preheater tower stack of 323℃ with the amount of 2.69 kg/kg of clinker. Three scenarios are intended to make use of waste heat. According to calculation results, the power was produced from each scenario, and due to those power techno-economic analyses of the power generating unit was performed. Because of its high steam upgrade, high production of power, high-cost savings, low payback period, low condenser load and high pumping power, scenario one was selected than scenario two and three.

The Evaluation of the thermal storage electric heating system Operation Management

Replacing fossil energy with the high proportion of renewable energy power in the field of enduse energy is the main way to reduce carbon emissions from energy combustion. Building heating is an important component in the field of end-use energy. The thermal storage electric heating system could use wind power during low power load periods at night for building heating. On the one hand, it helps to solve the problem of wind power accommodation, on the other hand it helps to achieve carbon emission reduction in the field of building heating. Based on the background of the thermal storage electric heating system for wind power accommodation, the influencing factors that affect the efficiency and benefits of electric heating system is analysed, and fuzzy comprehensive evaluation method based on analytic hierarchy process (AHP) is used to construct regenerative electric heating system operation management evaluation system.

Magnetostrictive iron–gallium alloy harvester with efficient two-mode AC–DC converting technology for effective vibration energy harvesting

A magnetostrictive vibration energy harvester based on an iron–gallium alloy composite cantilever beam is developed, and its capability is optimized from the aspects of bias magnetic field and the number of active layers. To solve the issue of low and irregular output voltage, it designs a converter suitable for a low-power harvester to make full use of the generated electric energy. A set of AC–DC converters with two working modes is designed by using the multiple voltage rectification method, which is able to directly drive low power load or store energy to supply power to higher power load. Through theoretical simulation and experiment, the converter’s characteristics, such as rectifier and filter characteristics, energy storage, and release process are systematically studied and tested. 1 V AC output voltage of the harvester is able to be converted into 5 V DC voltage after being processed by the converter. The proposed harvester provides an excellent vibration harvesting capacity that the AC normalized power density (power density per volume and acceleration) reaches 7.4 mW/(cm3/g). The harvesting system with the two-mode converter has achieved a high normalized DC output power vs AC input voltage of 630 µW/V. We have applied the harvester and converter for a low power electronic meter, which can work normally and display the time, temperature, and humidity in the laboratory. In addition, we have also applied the harvesting system for a higher power (1.2 W) electric fan with a universal serial bus (USB) port. After battery charging and IP5306 voltage boosting, the harvester meets the normal operation requirements of an electric fan with a USB port and it is able to operate normally.

Open-Loop Dynamic Modeling of Low-Budget Batteries with Low-Power Loads

Understanding dynamic behavior of a battery and the possibility of simulating it is necessary during design of IoT systems. This plays a critical role, especially for industrial devices with low-power demands planned for long lasting operation. While cost limitation mostly leads to use of the low-budget batteries with fast degradation, a model of these batteries supplying low-power loads is provided here. The overall model is in open-loop form because no access to the terminal measurements is available during the design phase. The identification process of the relation between the state of charge and related electromotive force as a key element of the model is discussed. Moreover, guidelines are suggested for identification of this relation. Furthermore, SoC estimation based on the Coulomb counting is modified to include a dynamic inter-cycle aging factor. This factor enables replication of the degradation within a single cycle. In spite of simplicity of this concept, it is able to reduce the model’s estimation error evaluated with two different types of loads. The overall model provides promising results with relative errors less than 0.2%.

Research on Non-Intrusive Load Monitoring Method Based on Feature Difference Enhancement

Non-intrusive load monitoring technology is the key technology to realize smart grid construction. The identification and classification of similar electrical appliances and low-power small-current electrical appliances in non-intrusive load monitoring has always been the focus of research and the difficulty of breakthrough. This paper uses current harmonic amplitude as classification data and based on the composition characteristics of harmonic amplitude data, and the current situation of fuzzy classification of similar electrical appliances, pointing out a method for enhancing the characteristic difference of harmonic amplitude data. This method can improve the current situation that the low-power electric load is difficult to identify when the low-power electric load and the high-power electric load work together. The status quo of identification has a good effect on the classification of low power and similar electrical load. In this paper, a non-intrusive load monitoring system is built, the bus current data is collected, and a feature database is built, and the network is used to classify the feature data and finally obtain the classification result. The experimental results show that the proposed method has a significant effect on the accuracy of classification and recognition of similar electrical appliances with similar eigenvalues.

Single DC Source Multilevel Inverter with Changeable Gains and Levels for Low-Power Loads

Different types of multilevel converters have been used to convert DC voltage to AC voltage for different applications. It is, however, desirable for flexible AC output voltage to be created from a single DC source at lower cost. This paper presents a new type of single DC source multilevel inverter which has the ability to create a different number of levels with low rate components. This device is also able boost the magnitude of the output voltage by means of a variable gain with one DC source. The advantages of the multilevel inverter are rapid stepping among levels, and its ability to produce different ranges of levels (seven, nine and eleven) and gains (two, four and eight). The proposed multilevel inverter includes six semiconductor switches, eight diodes, two capacitors and two inductors, making it suitable for low-power applications. A simulation in MATLAB and experimental tests on a prototype setup showed good performance for different modulations, with THD% down to 2.29%, which are meets the IEEE standard (IEEE 519).

Design of High Speed and Precision and Low-Power LVDS Driver for CMOS Image Sensor

Aiming at the requirement of high speed and precision, low-power and large-capacity load of serial data interface for aerospace super large array(15k×15k) CMOS image sensor, a design scheme low voltage differential signal (LVDS) driver by combining the split-length method with the pre-emphasis technique is proposed. Firstly, comparing with the general design schemes, the present scheme uses the split-length compensation method to increase effectively the unity-gain bandwidth while keeping the op-amp gain constant. Secondly, the pre-emphasis technique is used to compensate the LVDS driver for high-frequency components to improve the driving capability of the capacitive load and high speed signal integrity (SI). The simulation results show that the accuracy of the common-mode feedback voltage is improved by using the split-length compensation method, and also the common-mode voltage changes below 15 mV. The pre-emphasis technique is used to enhance the amplitude of the high-frequency components lost during the high-speed transmission. The quality of the signal eye diagram during high-speed transmission reduces the bit error rate, and both the transmission rate and the driving load capacity are two times more than the general design (1.2 Gb/s@12 pF), and the quiescent current consumption is only 4.6 mA@12 pF. The present LVDS driver design is implemented in a typical CMOS process of 0.18 μm.

Three-Phase Power Analyzer using Labview

An important requirement of power systems in this decade is the capability of power distribution among electrical devices and systems to improve power quality that depends on various factors, such as reactive, active, and apparent power. Virtual experiments and testing are considered important factors to achieve the best performance in this area. This research mainly aims to find low power factors and load to meet the requirements of electrical devices. Calculations are conducted on a real-time simulator LabVIEW to verify the effectiveness of linear and nonlinear values on the load to achieve the power factor.

An optimization approach to determining the power of active filters

The coal grading plants in Vietnam extensively apply asynchronous motors with frequency control. They consume reactive power and non-sinusoidal current from the supply network. The nonsinusoidal currents and voltages lead to additional energy losses in electrical equipments, reduce their service life and cause an economic damage. Because of the low load power factor the companies with such plants pay penalties to power supply utilities. These problems can be solved by the active filters. The paper suggests an optimization algorithm to calculate the power of the active filter, which provides a load power factor corresponding to the normative documents and power quality indices corresponding to the standard requirements. The algorithm is used to calculate the power of the active filter for the coal grading plant owned by the company “Kua Ong-Vinakomin”.

Research and Application of Thermoelectric Energy Conversion Device Based on Heat Dissipation of Coal Pile

In view of the spontaneous combustion of coal piles, waste of resources and environmental pollution, gravity heat pipes are inserted into coal piles, and the heat inside the coal piles will be extracted in time because of the high-efficiency thermal conductivity of the heat pipe phase change. In order to achieve energy conservation and environmental protection, a thermoelectric energy conversion device based on gravity heat pipe was designed, which can convert heat energy extracted from the coal pile into electrical energy for supply of low power loads. The results show that the gravity heat pipe can effectively suppress the temperature rise inside the coal pile; the coal body within 0.03m away from the gravity heat pipe is better in cooling effect; the thermoelectric energy conversion system is capable of converting thermal energy inside the coal pile into electric energy and supplying a low power load such as a wireless sensor.

THD minimization for Z-source-based inverters with a novel sinusoidal PWMswitching method

This paper presents a modified sinusoidal pulse width modulation (SPWM) switching method for one-phase and investigated two-phase impedance-source inverter structures. The proposed structure generates pulses for a quasi- Z-source converter and this block produces a unilateral voltage sine wave in the block's output. This signal is applied to the inverter as its input wave. For this purpose, the novel SPWM method is proposed for power switches while being switched complementarily. Two power switches are used in the structure to generate the pure sinusoidal output voltage and to minimize total harmonic distortion (THD), which is an essential parameter in inverter design. The results show that the proposed method generates the pure sinusoidal voltage and current signals for resistive and inductive loads and pure voltage and improved current waves for capacitive loads in comparison with existing techniques, since the THD of the output voltage and current signals is strongly affected by the dynamic loads. This method leads to final cost improvement and reduction of the size of the system with fewer number of components, which are essential parameters for renewable energy resource applications. A mathematical model is validated with the 2017a version of MATLAB/Simulink and 1.51% and 1.33% THD values are reported for low and high power loads, respectively, in the one-phase structure and 0.95% and 0.87% in the two-phase system. Finally, a 120 W prototype has been implemented and tested. A sine-wave with 620 Vac peak to peak amplitude and 50 Hz frequency has been gained in the inverter?s output and the quality of the voltage and current waveforms has been evaluated for different two 1.8 k$\Omega$ and 600 $\Omega$ resistive loads in the one-phase structure. Experimental results confirm all mathematical and simulation results.

Computer modeling of the vapour vortex orientation changes in the short low- temperature heat pipes

The results of computer studies of the vortex formation and orientation changes inside short heat pipes (HP’s) with profiled vapour channel in the Laval–liked nozzle form are presented. For the first time it was found that the vapour vortex of moist compressible vapour flow in the cooled part of vapour channel changes its rotational motion direction. The rotation direction of the toroidal vapour vortex is dependent on the heat power value, entering to the HP’s evaporator. With low heat power loads (a small temperature head) the rotational direction of the circular toroidal vapour vortex due to the Coanda effect and sticking moving vapour jets to the channel’s walls occurs from the periphery to the longitudinal axis of the vapour channel. While the heat power loads increasing, the direction of the toroidal vapour vortex ring rotation changes to the opposite, from the longitudinal axis to the periphery of the vapour channel. The thickness of the formed working fluid condensate film located under the toroidal vapour vortex also related to the evaporator heat power load and vapour vortex rotation direction. With weak temperature head, the vapour vortex rotates from the walls to the channel center and slow down the movement condensate film on the HP’s top cover surface to the capillary-porous insert, thereby increasing the effective film thickness. As the heat head increases, the vapour vortex rotation direction changes to the opposite one and direction of vapour flow and the liquid condensate film becomes the same, which leads to decrease in the effective film thickness. Experimental results of the condensate film thickness measurements, obtained with capacitive sensors show a sharp decrease in thickness with a temperature head increasing, what could be an indirect confirmation of the vapour vortex rotation direction changes. Numerical method for vapour turbulent flows based on Navier-Stokes (Reynolds) full equation system was used to calculate the moist vapour vortex flow in low-temperature HP’s.

Integrated Passive Devices and Switching Circuit Design for a 3D DC/DC Converter up to 60 V

This work presents the design and test of a switched-cap 3D DC/DC converter able to work up to 60[Formula: see text]V. The switches and the control circuits are integrated single-chip in a high-voltage (HV) MOS technology, and the passive devices are stacked on top of the chip. As an innovation versus the state-of-the-art, the work first presents the design of integrated passive devices, based on through silicon vias (TSV) MOS-compatible technology, which are suitable for switching converter applications up to 60[Formula: see text]V. Then, the implementation and experimental characterization of the switched-cap 3D DC/DC is proposed, with the silicon TSV capacitors stacked on top of the 0.35[Formula: see text][Formula: see text]m HV-MOS die. Compared with the state-of-the-art, the proposed 3D DC/DC converter is a compact circuit, able to directly regulate a wide input voltage range (from 6[Formula: see text]V to 60[Formula: see text]V) to a 5[Formula: see text]V, 2[Formula: see text]W output. Hence, it is suitable to supply low-power loads, such as control units and/or sensors, directly from the 48[Formula: see text]V power line available in hybrid vehicles or telecom and networking systems.

A Review of Carbon Capture and Storage Project Investment and Operational Decision-Making Based on Bibliometrics

The research on carbon capture and storage (CCS) project planning and investment and operational decision-making can provide a reference for enterprises to invest in CCS and for policy-makers to formulate policies to promote CCS development. So what are the current research hotspots in this field and the gaps that still need to be further studied in the future? This paper reviews the research in the field by a bibliometric analysis. The results show that the research in this field first focus on cost analysis, followed by project investment evaluation, project planning (cost curve and pipeline network), and project operation. In particular, fossil fuel power plants, pipeline transportation, and oil fields are the most crucial objects in the three technical links of CCS projects, respectively. Policies, carbon pricing, and uncertainty in cost and benefits are factors that are mainly discussed in this field. The methods used for CCS project planning are cost curve model and optimization model. The real option approach is suitable for the evaluation of investment decision-making. The evaluation of operational decision is mostly based on optimization model. The future research directions can be summarized as five points: (1) continuously and systematically update the calculated costs in the current research to the unified price of the latest year; (2) calculate the cost curve from the perspective of emission sources; (3) expand the planning region of pipeline network to the country, continent, and even the entire world; (4) pay more attention to the investment assessment of the CCS project that may be implemented with low cost and high return; and (5) analyze the optimal operation mode of CCS in the low-load power system.