Relative Efficiencies of Optimal Designs in Four Dimensions Constructed Using Balanced Incomplete Block Designs

Experimentally, the best design gives estimates of the desired effects and contrasts with maximum precision. Efficiency as a discriminating factor enables comparison of designs. The goal of Response Surface Methodology (RSM) is the determination of the best settings of the in-put variables for a maximum (or a minimum) response within a region of interest, R. This calls for fitting a model that adequately represents the mean response since such a model, is then used to locate the optimum. D-, A-, E- and T-Optimal designs of a rotatable design of degree two in four dimensions constructed using balanced incomplete block designs (BIBD) when the number of replications is less than three times the number of pairs of treatments occur together in the design and their relative efficiencies to general designs are presented. D-optimal design had 88 runs after replicating the factorial part twice and the axial part thrice with an optimal variance of 0.6965612 giving an efficiency of 97.7% while for A- and T-optimal designs they are formed with 112 runs each obtained by replicating the factorial part two times and axial part six times. Their optimal variances are 0.05798174 and 1.29828 respectively, with efficiency of 71.8% for A-optimal and 87.5% for T-optimal design. E-optimal design was found to be the most efficient design with an only 32 runs comprising only of the factorial part and with an optimal variance of 0.4182000, attaining an efficiency of approximately 1%. This study proposes the adoption of the E-optimal design in estimating the parameters of a rotatable second-order degree model constructed using BIBD for less costs and time saving.

OPTIMAL DESIGN OF DUAL STATOR-WINDING INDUCTION GENERATOR WITH PWM CONVERTER

To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load are proposed. The optimization method of excited capacitors to minimize the reactive power of the control winding at a variable speed is given. The calculation capacity of the machine with a diode bridge rectifier load is proposed. To achieve global searching, the integrated method with the improved real-coded genetic algorithm and the twodimensional finite element method （FEM） is introduced. Design results of the sample show that reactive power can be reduced by the method, and the converter capacity can be decreased to 1/3 of output rated power at the speed ratio of 1 ： 3, thus reducing the volume and the mass of the inverter.

Design Analysis of DC-DC Converters Connected to a Photovoltaic Generator and Controlled by MPPT for Optimal Energy Transfer throughout a Clear Day

The DC-DC converters are widely used in photovoltaic generating systems as an interface between PV module and the load. These converters must be chosen to be able to match the maximum power point (MPP) of PV module when climatic conditions change with different resistive load values. So DC-DC converters must be used with MPPT controller in order to reduce losses in the global PV system. This article focuses on the effect of climatic conditions on design of two components (inductance, capacitance) for three topologies of DC-DC converters commonly used in PV systems. When climatic conditions change, the boundary of inductance and capacitance parameters of DC-DC converter will change. These two parameters must be properly sized to achieve optimal efficiency for each converter. The design optimization is based on two principles: 1) for a steady-state operation in a continuous conduction mode, the inductance value for all choppers must be greater than the maximum value of boundary inductance, and 2) in order to limit the output voltage ripple of DC-DC converter below a desired value, the filter capacitance must be larger than the maximum value of boundary capacitance.

Weight and Efficiency Optimized DC/DC Converter Based on Multiple Interleaved Channels

Today, energy saving is one of the main objectives for engineers. In the case of mobile applications, energy can be saved by two different ways： decreasing the total masse of the system and increasing the efficiency of the overall system. This paper presents two optimization strategies to design a predefined multichannel structure of a boost converter which is dedicated to a solar airplane and used to interface PV panels and the battery system. The first strategy is a multi-criterion method that is able to trace the dependency between the converter＇s efficiency and its power density through the intermediary of the Pareto front. The second method, a mono-criterion approach, maximizes efficiency while respecting the constraint imposed on power density. The mono-criterion method that is applied to maximizing the European efficiency criterion showed that an increase in the number of channels enhanced the quantity of energy collected over a day by increasing the power density of the converter. At the end of the paper, the optimal design calculated was built to give an example of the result obtained by this design methodology. The results of the efficiency measurements made on a realized prototype are presented in this paper.

Design of High Efficiency DC-DC Converter for Photovoltaic Solar Home Applications

The solar energy conversion system is very interesting alternative on supplement the electric system generation, due to the persistent cost reduction of the overall system and cleaner power generation. To obtain a stable voltage from an input supply （PV cells） that is higher and lower than the output, a high efficiency and minimum ripple DC-DC converter required in the system for residential power production. Buck-boost converters make it possible to efficiently convert a DC voltage to either a lower or higher voltages. Buck-boost converters are especially useful for PV maximum power tracking purposes, where the objective is to draw maximum possible power from solar panels at all times, regardless of the load. This paper analyzes and describes step by step the process of designing, and simulation of high efficiency low ripple voltage buck-boost DC-DC converter for the photovoltaic solar conversion system applicable to a （typical） single family home based on battery-based systems. The input voltage can typically change from （20 V） initially, down to （5 V）, and provide a regulated voltage within the range of the battery （12 V）. PLECS simulation results provide strong evidences about the high efficiency, minimum ripple voltage, high accuracy, and the usefulness of the system of the proposed converter when applied to either residential or solar home applications.

Review of Design and Control Optimization of Axial Flux PMSM in Renewable-energy Applications

Axial flux permanent magnet synchronous motors(AFPMSMs)have been widely used in wind-power generation,electric vehicles,aircraft,and other renewable-energy applications owing to their high power density,operating efficiency,and integrability.To facilitate comprehensive research on AFPMSM,this article reviews the developments in the research on the design and control optimization of AFPMSMs.First,the basic topologies of AFPMSMs are introduced and classified.Second,the key points of the design optimization of core and coreless AFPMSMs are summarized from the aspects of parameter design,structure design,and material optimization.Third,because efficiency improvement is an issue that needs to be addressed when AFPMSMs are applied to electric or other vehicles,the development status of efficiency-optimization control strategies is reviewed.Moreover,control strategies proposed to suppress torque ripple caused by the small inductance of disc coreless permanent magnet synchronous motors(DCPMSMs)are summarized.An overview of the rotor-synchronization control strategies for disc contra-rotating permanent magnet synchronous motors(CRPMSMs)is presented.Finally,the current difficulties and development trends revealed in this review are discussed.

Recent developments in optimal experimental designs for functional magnetic resonance imaging

Functional magnetic resonance imaging(fMRI)is one of the leading brain mapping technologies for studying brain activity in response to mental stimuli.For neuroimaging studies utilizing this pioneering technology,there is a great demand of high-quality experimental designs that help to collect informative data to make precise and valid inference about brain functions.This paper provides a survey on recent developments in experimental designs for fMRI studies.We briefly introduce some analytical and computational tools for obtaining good designs based on a specified design selection criterion.Research results about some commonly considered designs such as blocked designs,and m-sequences are also discussed.Moreover,we present a recently proposed new type of fMRI designs that can be constructed using a certain type of Hadamard matrices.Under certain assumptions,these designs can be shown to be statistically optimal.Some future research directions in design of fMRI experiments are also discussed.

Evaluating the optimal porosity of fences for reducing wind erosion

Porosity is the most important parameter determining the shelter efficiency of fences. Wind measurements were made around fence models with different porosities in a wind tunnel. The optimal fence porosity is evaluated by means of Gandemer＇s method that combines the effects of wind reduction and turbulence fields on the shelter efficiency for abating wind erosion. Defining the optimal porosity must take into account of its own purposes, required shelter degree and area to be sheltered. Turbulence has profound impacts on the shelter efficiency of high degree. Two concepts： absolute optimal porosity and practical optimal porosity concerning optimal porosity are proposed. Choosing the practical optimal porosity means reducing cost without significant expense of shelter efficiency. According to the evaluation in present study, the absolute optimal porosity for providing high degree of shelter to abate wind erosion is 0.20 while the practical optimal porosity is around 0.40. Ifa less shelter degree but over wider area is required, the absolute optimal porosity ranges from 0.05 to 0.10 and the practical optimal porosity is 0.10. For any degree of shelter for abating wind erosion effectively, the fence porosity must be less than or equal 0.40.

A novel parameterization method for the topology optimization of metallic antenna design

In this paper, based on a tangential interpolation function and an adaptively increasing penalty-factor strategy(TIPS), a novel parameterization method with a self-penalization scheme aimed for the topology optimization of metallic antenna design is proposed. The topology description is based on the material distribution approach.The proposed tangential interpolation function aims to associate the material resistance with design variables, in which the material resistance is expressed in the arctangent scale and the arctangent resistance is interpolated with the design variables using the rational approximation of material properties. During the optimization process, a strategy with an adaptively increasing penalty factor is used to eliminate the remaining gray scale elements, as illustrated in examples,in the topology optimization based on the proposed tangential interpolation function. Design results of typical examples express the effectiveness of the proposed TIPS parameterization.

Optimization study and design of scintillating fiber detector for DT neutron measurements on EAST with Geant4

Real-time monitoring of the 14-MeV D-T fusion neutron yield is urgently required for the triton burnup study on the Experimental Advanced Superconducting Tokamak (EAST). In this study, we developed an optimal design of a fast-neutron detector based on the scintillating fiber (Sci-Fi) to provide D-T neutron yield through Geant4simulation. The effect on the detection performance is concerned when changing the number of the Sci-Fis embedded in the probe head, minimum distance between the fibers, length of the fibers, or substrate material of the probe head. The maximum number of scintillation photons generated by the n/γ source particles and output by the light guide within an event (event:the entire simulation process for one source particle) was used to quantify the n/γ resolution of the detector as the main basis. And the intrinsic detection efficiency was used as another evaluation criterion. The results demonstrate that the optimal design scheme is to use a 5 cm probe head whose substrate material is pure aluminum, in which 463 Sci-Fis with the same length of 5 cm are embedded, and the minimum distance between the centers of the two fibers is 2 mm. The optimized detector exhibits clear directionality in the simulation, which is in line with the expectation and experimental data provided in the literature. This study presents the variation trends of the performance of the SciFi detector when its main parameters change, which is beneficial for the targeted design and optimization of the Sci-Fi detector used in a specific radiation environment.

Paralleled DC-DC Power Converters Sliding Mode Control with Dual Stages Design

This paper proposes the new cascaded series parallel design for improved dynamic performance of DC-DC buck boost converters by a new Sliding Mode Control (SMC) method. The converter is controlled using Sliding Mode Control method that utilizes the converter’s duty ratio to determine the skidding surface. System modeling and simulation results are presented. The results also showed an improved overall performance over typical PID controller, and there was no overshoot or settling time, tracking the desired output nicely. Improved converter performance and robustness were expected.

Optimized Simulation Design of Double Glass Curtain Wall Shading System in Hot Summer and Cold Winter Zone

The glass curtain wall is widely favored by the owners for its good appearance modeling efthct. In using process, however, excessive energy consumption, low level indoor eomtort and other problems of glass curtain wall are often exposed. Aiming at office buildings in hot Summer and cold Winter zone, taking the optimization of thermal comfort of double glass curtain wall in the summer and the reduetion of building energy consumption throughout the year as the breakthrough point, using the method of energy simulation analysis, through changing the size of internal shading component in the simulated room, this paper analyzes and summarizes the variation law of its energy consumption value, to explore the relatively reasonable design plan of shading systems of the building with glass curtain wall.

Optimization of the Impeller Geometry for an Automotive Torque Converter Using Response Surface Methodology and Desirability Function

Response surface methodology (RSM) based on desirability function approach (DFA) is applied to obtain an optimal design of the impeller geometry for an automotive torque converter. The relative importance of six design parameters including impeller blade number, blade thickness, bias angle, scroll angle, inlet angle and exit angle is investigated using orthogonal design approach. The impeller inlet angle, exit angle and bias angle are found to exert the greatest influence on the overall performance of a torque converter, with two flow area factors being considered, namely 17% and 20%. Then, RSM together with central composite design (CCD) method is used to in-depth evaluate the interaction effect of the three key parameters on converter performance. The results demonstrate that impeller exit angle has the strongest impact on peak efficiency, with larger angles yielding the most favorable results. The stall torque ratio maximization is attainable with the increase of impeller bias angle and inlet angle together with smaller exit angle. In the end, an optimized design for the impeller geometry is obtained with stall torque ratio and peak efficiency increased by 1.62% and 1.1%, respectively. The new optimization method can be used as a reference for performance enhancement in the design process of impeller geometry for an automotive torque converter.

IE3 Efficiency Induction Motors with Aluminum and Copper Rotor Cage： Technical and Economic Comparison

The aim of this study was to design three-phase induction motors with aluminum and copper cage, in the range 0.75 ÷22 kW, to fulfill the 1E3 efficiency level according to typical performance and standard constraints. The proposed study has concerned TEFC （ totally Enclosed Fan-Cooled ）, 400 V, 50 Hz, SI duty three phase squirrel-cage induction motors only. The motors＇ designs, with AI and Cu cage, have been optimized in order to reach the minimum efficiency level IE3 at lowest active material costs and satisfy the physical and performance constraints of the designs, which are the motor specifications. A suitable optimization procedure has been used which allowed to find the ＂best design＂ by chancing the geometric dimensions of the stator, rotor shape, the stator winding and the stack length. In order to guarantee the goodness and feasibility of the optimized designs, several constrains have been imposed.

Some Construction Methods of A-Optimum Chemical Balance Weighing Designs

Some new construction methods of the optimum chemical balance weighing designs and pairwise efficiency and variance balanced designs are proposed, which are based on the incidence matrices of the known symmetric balanced incomplete block designs. Also the conditions under which the constructed chemical balance weighing designs become A-optimal are also been given.

基于遗传算法的风电齿轮传动系统参数优化设计

齿轮箱是风力发电系统的重要部件,其体积大、重量高等问题制约了风电清洁能源的发展.以1.5 WM风力发电机组为研究对象,建立齿轮传动系统轻量化数学模型,并采用遗传算法进行优化求解.结果表明,采用遗传算法是可行的,优化后齿轮传动系统体积减少了4.59%,这将进一步减小齿轮传动系统箱体体积和总质量.通过计算行星轮系的传动效率,验证了优化结果的可行性,该研究将为风电齿轮传动系统轻量化设计提供新方法.

基于移相控制统一模型的双有源桥DC-DC变换器基波环流优化控制策略

为充分利用双有源桥DC-DC变换器的容量,减小无功功率,提升工作效率,提出一种基于变换器移相控制统一模型的基波环流优化控制策略。通过引入基波移相比对变换器的所有移相控制方式进行统一描述,并采用傅里叶分解法建立全桥交流电压及电感电流的统一模型。该统一模型降低了多控制变量下变换器多模态分析的复杂性,适用于不同移相控制的所有工作模式,具有普适性。基于频域分析法和功率因数角,构建变换器传输功率及无功功率的统一数学模型。在此基础上,提出考虑无功基波分量的环流优化控制策略,并对传导损耗进行建模与分析。该策略简单有效,能够很好地减小变换器无功功率和改善系统效率,更有利于工程实际的应用。搭建了实验平台,对比了所提基波环流优化控制策略与传统移相控制方式下变换器的功率因数及变换效率,仿真和实验结果验证了理论分析的正确性和所提控制策略的可行性。

基于“仿真—半实物仿真—实物”三阶段开发流程的DAB变换器实验探索与研究

该文以双有源桥DC-DC变换器为对象,详细分析了变换器在三重移相调制下的两种数学模型,又基于这两种数学模型提出了对应的电感电流优化控制策略,搭建了包含MATLAB/Simulink仿真平台、StarSim半实物仿真平台和实物平台的三阶段实验平台,在平台中通过实验验证了优化控制策略的可行性和有效性。所设计的三阶段开发流程能够加深学生对电力电子领域相关知识的理解,逐步提升学生的理论分析能力、仿真验证能力和实践操作能力。

三相CLLC谐振变换器磁集成平面变压器设计与优化

三相CLLC谐振变换器凭借其高效率、大容量、低器件应力等优势而受到广泛关注。然而,多相结构的磁性元件数量多、体积大,是制约功率变换器尺寸的主要因素。随着宽禁带(WBG)半导体器件的出现,功率变换器的开关频率显著提高,这也为印制电路板(PCB)绕组的使用提供了有利条件。与传统绕线式绕组相比,PCB绕组的扁平特性更适用于平面磁性元件。此外,由于高频带来的低电感需求也使得基于PCB绕组的平面磁性元件更有利于实现集成。该文提出一种新型的基于PCB绕组的电感和变压器的集成结构,详细分析磁心结构的磁路模型,并给出集成磁件的优化设计方法,最后通过搭建一台基于SiC器件的800 V/10 kW的实验样机进行验证。实验结果表明,该集成方案可有效减小变换器的体积和损耗,具有高功率密度和高效率。

旋风分离器内置导流叶片结构参数优化研究

为研究旋风分离器内置导流叶片各个结构参数之间的相互作用,基于CFD数值模拟方法和BBD试验设计,采用二阶多项式基函数建立了Stairmand旋风分离器的叶片轴向位置、叶片长度及叶片偏转角度与分离效率及压降间的数学模型。拟合结果表明:响应目标的决定系数均在0.99以上,表明相关性和回归模型效果较好。使用Design Expert软件处理数据后选择了最佳推荐点,对分离器结构进行了优化。优化后的模型与原结构对比结果如下:优化模型的压降略有上升;颗粒直径在1~20μm范围内时,优化前后分离器的分离效率变化明显,尤其在1~15μm范围内时,优化前分离效率为6.8%~31.0%,优化后则达到了17.0%~54.0%,提升约20个百分点;而当粒径在15~40μm区间时,优化前后的分离效率变化不明显,尤其是在粒径20~40μm时,优化前的分离效率为71.0%~98.0%,而优化后的分离效率只有77%~99%,提升约10个百分点;优化后的模型性能符合“高效低阻”的设计目标。所得结论可为旋风分离器内置叶片的改进提供设计指导。