Parameter Identification Process Research Articles

Universal Virtual Synchronous Generator Based on Extended Virtual Inertia to Enhance Power and Frequency Response

Virtual synchronous generators (VSG) are considered a new generation of grid-friendly inverters with the same inertial support characteristics as synchronous generators (SG). However, the inertia support comes with the side effects of power and frequency response deterioration. The existing VSG power oscillation suppression methods have limitations such as complex controller parameter tuning, altering the frequency support characteristics, and power quality degradation. To address these issues, this paper proposes a universal VSG control strategy based on extended virtual inertia (VSG-EVI). Herein, the virtual inertia is no longer a constant or varying number; it is endowed with frequency domain characteristics to improve the VSG transient responses. Moreover, a detailed parameter design process is given in detail. Compared with the conventional VSG (CVSG), VSG-EVI significantly suppress the power and frequency oscillations. Compared with the existing VSG oscillation suppression methods, VSG-EVI addresses the issues of the reduction of frequency support capability, whereas the controller parametric design process is simplified with the proposed intuitive extended virtual inertia. Finally, the proposed VSG-EVI method is thoroughly validated by experiments under both grid-connected and stand-alone modes.

An active equalization method for series-parallel battery pack based on an inductor

The equalization topologies based on inductive energy storage have high equalization accuracy and perfect functionality, but often have more complex structure and control method. To overcome this problem, an active equalization method based on an inductor is proposed for the series-parallel battery pack. The energy storage device responsible for energy transfer requires only one inductor and the topology is simple and low cost. Combining diodes and MOSFETs to form a switching array reduces the cost of the equalization topology while increasing the fault tolerance of the control signal and making equalization control simpler. First, the working principle and parameter design process of the topology are described, and the control strategy adapted to it is proposed on this basis. Second, based on the simulation models, the variation law of the efficiency and speed of the proposed equalization method influenced by inductance and switching frequency is analyzed, and by comparing the new equalization method with similar methods, it is verified that the new equalization method is simple in structure, low in cost, and convenient in control. Final, by building an experimental platform for “four-series and two-parallel” battery pack, the effectiveness of the new equalization method is verified.

Multi-Objective Parametric Optimization Design for Mirrors Combined with Non-Dominated Sorting Genetic Algorithm

The process of intelligent multi-objective parametric optimization design for mirrors is discussed in detail in this paper, with the error of the mirror surface shape and the total mass being examined as the optimization objectives. The establishment of complex objective functions for solving the optimization problem of the mirror surface shape error was realized, and manual modification of the model was avoided. Moreover, combining this with a non-dominated sorting genetic algorithm (NSGA) helped the Pareto front move towards an ideal optimal set of solutions. To verify the effectiveness of the proposed method, an aluminum alloy mirror with an aperture of 140 mm was taken as an example. The Pareto optimal solution set of the mass and surface shape error under 1 g gravity was obtained for finding the required solution and satisfying the optimization goal. In addition, this method is applicable to other complex structural design problems.

An Active Equalization Method Based on an Inductor and a Capacitor for Series Battery Pack

Combining the characteristics of the high precision of inductive energy storage equalization and the fast speed of capacitive energy storage equalization, an active equalization method is proposed for a series battery pack based on an inductor and capacitor. The energy storage devices responsible for energy transfer have only one inductor and one capacitor. First, we propose the topology, analyze the working principle, and elaborate on its parameter design process. Second, an adaptive equalization control strategy matching the topology is designed. Third, based on the simulation models, the speed and efficiency characteristics of the new equalization method are verified, and the significant cost and volume advantages and the simple control characteristics are analyzed in detail. Finally, an experimental platform was built for a four-cell series battery pack to verify the effectiveness of the new equalization method for the battery pack charging and discharging process. The voltage difference is less than 80 mV.

DFMA-oriented modular and parametric design and secondary splitting of vertical PC components

The design and production of assembled buildings are difficult to standardise, which limits their extensive application. In this paper, the design for manufacture and assembly (DFMA) concept is applied to the design of vertical precast concrete (PC) components for assembled buildings. Taking vertical PC components as an example, the rapid modelling and whole life-cycle application of DFMA-oriented PC components for assembled buildings are investigated. Firstly, the modular design method is introduced. By combining parametric design and building information modelling (BIM), we propose a modular, parametric design method and process of PC components based on DFMA. Secondly, the design of standard modules after secondary splitting is introduced for a better DFMA-oriented parametric design of PC components. We explored the secondary development process of DFMA and BIM and the module creation process of the parametric standard based on family templates and DFMA. Thirdly, based on the parametric standard module, the application of the optimised whole life cycle of design, manufacture and assembly of PC components is introduced. Finally, the feasibility of this method is verified by practical cases. The design process for PC components is fast, accurate and standardised. The integrated application of BIM is accelerated, and digital collaboration in assembly construction is strengthened. The study results are conducive to establishing a standardised design and production system for PC components, reducing design costs, improving design efficiency and the comprehensive benefits of assembled buildings.

Feasibility study of AZ31B deposition made by novel powder bed friction stir process with optimal process parameters and tool features selection

The current work focused on the feasibility study of an in-house developed process at a laboratory scale named Powder Bed Friction Stir (PBFS) for AZ31B powder deposition. It employs friction stirring as a heating source instead of a laser or electron beam, as in powder bed fusion which can potentially mitigate the issues arising from liquid-solid phase transformation. A suitable process parameter and tool design was chosen through experimentation. Two sets of process parameters were selected for rotational and translational motion as 1200 rpm & 900 rpm and 360 mm/min & 200 mm/min, respectively. The material deposition is affected by tool design, so five different tools were explored. The overall height of the successful deposition was 7 mm with process parameters 1200 rpm & 360 mm/min, and (Circular Protruded Feature) CPFII tool in total 35 passes keeping layer thickness (0.2 mm). Microstructure and phase analysis were carried out using (Scanning Electron Microscopy) SEM and (X-ray Diffraction) XRD, respectively, to study the grain refinement, presence of (Inter Metallic Compounds) IMCs, and participation of the slip system in the deformation process. The resulting grain refinement was 78%, with increased basal plane intensity in the deposit. The current study offered an extension of solid-state additive manufacturing as PBFS for Mg alloys.

Parameter Design of Half-Bridge Converter Series Y-Connection Microgrid Grid-Connected Filter Based on Improved PSO-LSSVM

The half-bridge converter series Y-connection microgrid (HCSY-MG) is a new type of series microgrid. In order to reduce the harmonic content in HCSY-MG grid-connected current and at the same time simplify the parameter design process of the LCL filter, this study proposed an LCL filter parameter design method based on an improved particle swarm optimization-least squares support vector machine (PSO-LSSVM) by analyzing the harmonic characteristics of the HCSY-MG grid-connected current. In addition, to enhance the convergence speed of PSO-LSSVM, the inertia factor during its parameters’ update is made to adjust adaptively according to the direction of two consecutive parameter changes to constitute an improved PSO-LSSVM. Through simulation and comparative analysis, it is demonstrated that the improved PSO-LSSVM can enhance the convergence speed; the proposed filter parameter design method can effectively reduce the harmonic content in the HCSY-MG grid-connected current and is simpler and more comprehensive than the existing design method.

Property-Graded Stainless Steel 316L by Selective Laser Melting: Characterization & Design

Abstract The purpose of this research work is to characterize and inform the design of (mechanical) property-graded bulk structures made from a single metallic alloy via a laser powder bed fusion (LPBF) process, with an end goal of creating repeatable/reproducible functionally-graded additively manufactured (FGAM) parts. This paper specifically investigates the manufacture of stainless steel (SS) 316L structures via a pulsed selective laser melting (SLM) process, and the underlying causes of property variations (within a functionally-acceptable range) through various material characterization techniques. For this, a design of experiments spanning the volumetric energy density (VED) based process parameter design space was utilized to investigate the range of functionally-acceptable physical/mechanical properties achievable in SS 316L. Five sample conditions (made via different process parameter combinations) were down-selected for in-depth microstructure analysis and mechanical/physical property characterization; these were suitably selected to impart a wide and controllable property range (209–318 HV hardness, 90–99.9% relative density, and 154–211 GPa modulus). It was observed that property variations resulted from combinations of porosity types/amounts, martensitic phase fractions, and grain sizes. Based on these findings, property-graded standard test specimens were designed and manufactured for further investigation—tensile specimens having a monotonic hardness change along its gauge length, four-point bending specimens with varying elastic moduli as a function of the distance from the neutral axis, and Moore’s rotating beam fatigue specimens with moduli variations based on the distance from the center. Altogether, this work lays the foundation for understanding and designing the local and global mechanical performance of FGAM bulk structures.

A comparative study of fractional-order models for lithium-ion batteries using Runge Kutta optimizer and electrochemical impedance spectroscopy

With the popularity of new energy vehicles and various electronic products, lithium-ion batteries are widely used in daily life. For lithium-ion batteries, an accurate model is the basis of battery management. In the process of continuous pursuit for model accuracy, it often leads to an increase in model complexity. Fractional-order models can effectively balance model accuracy and complexity between electrochemical models and equivalent circuit models, thus having good application prospects. In this paper, four typical fractional-order models for lithium-ion batteries are compared, and the Runge Kutta optimizer (RUN) algorithm, which has fast convergence speed and high precision, is employed to identify the model parameters. The accuracy for predicting terminal voltage and the time required for parameter identification process are compared respectively under different dynamic conditions for each model. Finally, the model impedance spectrum fitted results and model parameter values are discussed through electrochemical impedance spectroscopy test. This paper provides guidance on the modeling and parameter identification for lithium-ion batteries through analyzing different fractional-order models and introducing impedance spectroscopy to help explore the battery characteristics.

A Multirelay Wireless Power Transfer System With Double-Sided LCC Compensation Network for Online Monitoring Equipment

A multirelay wireless power transfer (WPT) system with the double-sided inductor-capacitor-capacitor (LCC) compensation network for the online monitoring equipment on the high-voltage transmission line is proposed. Constant-voltage (CV) or constant-current (CC) output characteristics is achieved. The proposed topology does not use ferrite materials, and the LCC compensation networks are only utilized at the transmitter and the receiver. Each relay coil is only connected in series with one compensation capacitor. Three working modes are proposed according to the resonance conditions of Tx compensation network, Rx compensation network, and compensating capacitances of relay coils. CC and CV output characteristics in each mode are analyzed and compared by simulation in terms of system output attenuation with load changes and frequency sensitivity. The parameter design process is given. A six-coil experimental prototype is built to validate the correctness and feasibility of the theoretical analysis.

Reconfigurable Rectifier-Based Detuned Series-Series Compensated IPT System for Anti-Misalignment and Efficiency Improvement

For an inductive power transfer (IPT) system, mobility is one of the most attractive features, but coupling variations can dramatically affect the system's output. In this article, a reconfigurable rectifier-based detuned series-series (SS) compensated IPT system is proposed to tolerate an extensive coupling range and improve the system efficiency simultaneously. The reconfigurable rectifier, which can operate in a full-bridge rectifier mode or a half-bridge rectifier mode, is used to alter the equivalent ac load from one value to the other so the expected coupling range of the detuned SS topology can be extended. At the same time, the system efficiency is also partly improved because the ac load is changed to get closer to the optimal load of the IPT system. First, a detuned SS IPT system with the reconfigurable rectifier is presented and followed by the analysis of the working modes. Then, a detailed parameter design process and switching control of the reconfigurable rectifier are introduced. Finally, a 400-W prototype was constructed to verify the validity of the proposed method. The experimental results demonstrate that the output power fluctuation of the proposed IPT system is less than 17.5% and the lowest efficiency can be improved from 68.6% to 87.5% with the coupling coefficient varying from 0.1 to 0.4. The proposed method can implement significant antimisalignment and efficiency improvement simultaneously, and it is regarded as a potential solution for low-power IPT applications with high spatial mobility.

A High Efficiency and Wide Voltage Gain sLC_LCC DC–DC Converter With SiC Devices

A novel s <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> _ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> resonant dc–dc converter is proposed in this article. With the combination of a notch filter and a new s <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> excitation structure of the transformer, wide and fast gain characteristics are obtained. With the frequency modulation, the notch filter structure helps the converter realize a wide output voltage range adjustable from zero theoretically. Besides, the fast voltage gain regulation capacity is achieved in a narrow frequency range with the s <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> excitation structure. In the text, topology structure, operation principle, and characteristics analysis are illustrated in detail. For numerous passive components, an effective design method is necessary to guide parameter determination. And a detailed parameter design process is discussed. With the selected parameters, the soft-switching feature is realized. Finally, a 500 W experimental prototype is fabricated to verify the feasibility and effectiveness of theoretical analysis. The converter achieves 59.3–16.3 V output voltage regulation ability in a narrow frequency range (86 kHz, 189 kHz) under the condition of power 500 W and input voltage 375 V. High efficiency is maintained in the full load range, and the maximal efficiency of the converter reaches 97.7% at 99.5 kHz.

Identification of Differential Drive Robot Dynamic Model Parameters.

The paper presents the identification process of the mathematical model parameters of a differential-drive two-wheeled mobile robot. The values of the unknown parameters of the dynamics model were determined by carrying out their identification offline with the Levenberg-Marguardt method and identification online with the Recursive least-squares method. The authors compared the parameters identified by offline and online methods and proposed to support the recursive least squares method with the results obtained by offline identification. The correctness of the identification process of the robot dynamics model parameters, and the operation of the control system was verified by comparing the desired trajectories and those obtained through simulation studies and laboratory tests. Then an analysis of errors defined as the difference between the values of reference position, orientation and velocity, and those obtained from simulations and laboratory tests was carried out. On itd basis, the quality of regulation in the proposed algorithm was determined.

Prototyping of digitally manufactured thin glass composite façade panels

The use of thin glass promises to enable a variety of construction industry pursuits. In addition to the ecological benefits of more efficient use of resources, architects can anticipate new design freedoms with thin glass. Based on the sandwich theory, the flexible thin glass can be combined with a 3D-printed open-cell polymer core to form a very rigid yet lightweight composite element. This paper presents an exploratory attempt on the digital manufacturing of thin glass composite façade panels with an industrial robot. It explains the idea of a digital “file-to-factory”-workflow which includes Computer-Aided Design (CAD), Engineering (CAE) and Manufacturing (CAM). The research shows a parametric design process to enable the seamless integration of digital analytic tools. Furthermore, this process shows the potentials and challenges of the digital manufacturing of a thin glass composite panel. Here, partial production steps executed by an industrial robot arm, such as large-format additive manufacturing, mechanical surface preparation, bonding and assembly process are explained. Finally, a first insight into mechanical properties of the composite panel are experimentally and numerically investigated and evaluated under surface load. The general concept of the digital design and manufacturing workflow as well as the results of the experimental study provide the background for the integration of further form-finding and analysis methods as well as the implementation of extensive mechanical investigations in future research.

Imaging of Liposomes by Negative Staining Transmission Electron Microscopy and Cryogenic Transmission Electron Microscopy.

Morphological characteristics of liposomes, such as size and lamellarity directly impact their quality and biological performance of encapsulated drug. Gaining insights into these parameters mayalso help ensure identification and utilization ofmost efficient processparameters for liposomesmanufacturing. Direct imaging of such self-assembling colloidal structures, although challenging, is feasible through transmission electron microscopy (TEM) which uses nanometer scale wavelength of electronsfor illumination, enabling an accurate assessment of the morphological characteristics of liposomes. This chapter willprovide background information on the working principle and general sample preparation procedure for the two most commonly used TEM techniques for imagingliposomes, viz. negative staining transmission electron microscopy and cryogenic transmission electron microscopy.

A conceptual framework for layerwise energy prediction in laser-based powder bed fusion process using machine learning

Additive Manufacturing (AM) is the process of successively joining materials layer by layer to produce a component from a digital 3D model. One of the widely adopted AM processes for producing metal components is laser-based powder bed fusion of metals (PBF-LB/M), in which lasers are used to selectively melt and fuse metallic powder in successive steps. An essential step towards economic industrial application is to minimize the energy consumption of the technology. Therefore, it is important to understand the relation between the process parameters (e.g., scanning speed, layer thickness, build time, laser power), part design, working environment, and the energy required to manufacture a component. In this work, we propose a conceptual framework of multimodal regression (MMR) for layerwise energy and quality prediction in AM process. The MMR model can be implemented using neural networks and used to analyze 2D images and process information of a layer to predict the layer quality and energy required to manufacture the layer. This model can further be used to optimize the part geometry, process design, and machine level parameters to utilize less energy without compromising on quality. Additionally, a PBF-LB/M use case is provided to discuss the feasibility of the proposed framework.

Comparison of Data-Driven Modeling and Identification Approaches for a Self-Balancing Vehicle

This paper gives a systematic comparison of different state–of–the–art modeling approaches and the corresponding parameter identification processes for a self–balancing vehicle. In detail, a nonlinear grey box model, its extension to consider friction effects, a parametric black box model based on regression neural networks, and a hybrid approach are presented. The parameters of the models are identified by solving a nonlinear least squares problem. The training, validation, and test datasets are collected in full–scale experiments using a self–balancing vehicle. The performance of the different models used for ego–motion prediction are compared in full–scale scenarios, as well. The investigated model architectures can be used to improve both, simulation environments and model–based controller design. This paper shows the upsides and downsides arising from using the different modeling approaches. Videos showing the self–balancing vehicle in action are available at: https://tinyurl.com/mvn8j7vf

Testing of uncovered solar thermal collectors under dynamic conditions and identification of performance parameters - for nocturnal radiative cooling applications

This paper presents the first part of a research-work conducted at the University of Applied Sciences (HFT-Stuttgart). The aim of the research was to investigate the potential of low-cost renewable energy systems to reduce the energy demand of the building sector in hot and dry areas. Radiative cooling to the night sky represents a low-cost renewable energy source. The dry desert climate conditions promote radiative cooling applications. The system technology adopted in this work is based on uncovered solar thermal collectors integrated into the building's hydronic system. By implementing different control strategies, the same system could be used for cooling as well as for heating applications. This paper focuses on identifying the collector parameters which are required as the coefficients to configure such an unglazed collector for calibrating its mathematical model within the simulation environment. The parameter identification process implies testing the collector for its thermal performance. This paper attempts to provide an insight into the dynamic testing of uncovered solar thermal collectors (absorbers), taking into account their prospective operation at nighttime for radiative cooling applications. In this study, the main parameters characterizing the performance of the absorbers for radiative cooling applications are identified and obtained from standardized testing protocol. For this aim, a number of plastic solar absorbers of different designs were tested on the outdoor test-stand facility at HFT-Stuttgart for the characterization of their thermal performance. The testing process was based on the quasi-dynamic test method of the international standard for solar thermal collectors EN ISO 9806. The test database was then used within a mathematical optimization tool (GenOpt) to determine the optimal parameter settings of each absorber under testing. Those performance parameters were significant to compare the thermal performance of the tested absorbers. The coefficients (identified parameters) were used then to plot the thermal efficiency curves of all absorbers, for both the heating and cooling modes of operation. Based on the intended main scope of the system utilization (heating or cooling), the tested absorbers could be benchmarked. Hence, one of those absorbers was selected to be used in the following simulation phase as was planned in the research-project.

A novel nonlinear decreasing step-bacterial foraging optimization algorithm and simulated annealing-back propagation model for long-term battery state of health estimation

With the rapid development of electric energy storage, more and more attention has been paid to the accurate construction of energy storage lithium-ion battery (LIB) model and the efficient monitoring of battery states. Based on this requirement, a simulated annealing-back propagation (SA-BP) model is proposed, and the long-term state of health (SOH) of LIBs can be estimated online by combining with the battery single particle (SP) model. Among them, simulated annealing (SA) algorithm is used to optimize the initial parameters of back propagation (BP) network. In order to improve the identification efficiency and avoid the local optimization, the nonlinear decreasing step-bacterial foraging optimization (NDS-BFO) algorithm is introduced into the parameter identification process. On the basis of adopting the SOH sequence as the output of the SA-BP model, two electrochemical parameter sequences are used as the input of the model for training and testing. In addition, in this paper, the contributions in terms of the SOH estimation task mainly include two aspects. Firstly, the SOH estimation results can provide suggestions for the timely replacement of batteries in actual energy storage power stations. Secondly, the electrochemical parameters identified before SOH estimation are strongly related to the quality of the LIB. Therefore, they can provide references for the economy of LIBs. At 25 °C, the accuracy of the SP model is verified under three different working conditions. Degradation experiments are carried out under a constant current condition and a self-designed energy storage condition. The experimental results show that, under the 0.5 rate constant current condition, the root mean square error (RMSE), mean absolute error (MAE) and mean absolute percentage error (MAPE) of the long-term SOH estimation result are 0.42 %, 0.34 % and 0.38, respectively. And under the self-designed energy storage condition, the RMSE, MAE and MAPE of the result are 0.33 %, 0.26 % and 0.29, respectively. Under the same working condition, the SOH estimation results have a significant improvement in various performance evaluation indicators. The improved algorithm provides theoretical and experimental basis for the reliability of energy storage battery monitoring.

Trajectory Tracking Control of a Mobile Robot with the ROS System

This article provides a simulation and laboratory study of a control system for a two-wheeled differential-drive mobile robot with ROS system. The authors propose an approach to designing a control system based on a parametric model of the robot’s dynamics. The values of unknown parameters of the dynamic model have been determined by means of a Levenberg-Marguardt identification method. By comparing the desired trajectories with those obtained from simulation and laboratory tests, and based on errors analysis, the correctness of the model parameter identification process and the control system operation was then determined.