On the design of high‐efficiency linear induction motors for linear metro

Linear metro with single‐sided linear induction motor (SLIM) propulsion and wheel‐on‐rail support and guidance came into service in April 1990 in Osaka and in December 1991 in Tokyo, and is under construction or planned for Yokohama, Kobe, and Fukuoka. Since the new traffic system is used widely, it is of great importance to decrease its energy consumption. In this paper, the design of the SLIM for the linear metro is formulated as a constrained nonlinear programming problem, and optimum design is carried out to maximize efficiency. Seven parameters are chosen as independent variables: number of poles, pole pitch, stack height, secondary aluminum sheet thickness, overhang length, slot width/slot pitch ratio, and rated slip. The output KW/input KVA ratio, maximum flux density in teeth, temperature rise, primary length, stack height, overhang length, maximum thrust, and vertical force are selected as constraint functions. In the optimization procedure, the performance characteristics are formulated by space harmonic analysis taking account of the end effect, skin effect, and air gap leakage. The accuracy of the formulas is verified against experimental results. Effective ways of increasing efficiency include the addition of a copper reaction plate and minimization of the mechanical clearance. © 2001 Scripta Technica, Electr Eng Jpn, 137(2): 36–43, 2001     

Fully parameterized fixed‐order controller design for H∞ loop shaping method using frequency responses—extension to MIMO systems

Robust control is often applied to systems with uncertainties and disturbances. Above all, the H∞ loop shaping method is known to achieve good control performance and robustness. In this method, the final controller consists of weighting functions and a stabilizing controller. The stabilizing controller is derived for the shaped plant to suppress the H∞ norm of the transfer matrix consisting of a sensitivity function, a complementary sensitivity function, and so on. In addition, the stabilizing controller improves robust stability margin while keeping gain characteristic of the shaped plant if weighting functions are suitable. As a result, the closed‐loop system is well‐balanced between good tracking and robustness. However, a final controller tends to be high‐order. For this problem, reduction techniques are often applied to the final controller. In this case, performance and stability is not always adequately evaluated due to errors by the controller reduction. This paper proposes a fully parameterized fixed‐order controller design method using frequency responses of the plant. We formulate a design problem for multi‐input–multi‐output systems as an optimization problem. Therefore, we can directly design a low‐order controller from frequency responses using the iterative LMI optimization. Accordingly, we can avoid to deteriorate the evaluation of performance and stability.     

直线异步电机在线搜索法效率优化控制

直线异步电机具有较好的直接传动特性,但是由于气隙较大以及边端效应的存在,运行效率较低.本文提出了一种在线搜索效率优化方法,能够提高电机轻载运行时的效率,降低电机能耗.该方法采用黄金分割法进行全局寻优,搜索确定励磁电流分量与推力分量之间的最优比率.算法收敛速度较快,不依赖电机模型参数,而且不需要随电机负载力变化而重新启动搜索.实验结果验证了算法的正确性与电机效率优化效果.     

一种新型的直线异步电机参数测量方案

单边直线异步电机(SLIM)的T型电路参数是电机控制的基础,它在无速度传感器控制和在线参数辨识中更为重要.SLIM相对旋转异步电机(RIM)存在气隙大、边缘效应等,若采用RIM开路和短路试验方法,会给参数测量带来较大误差.本文提出一种适合SLIM参数测定的新型方案,只需测量电机输入端的总功率、相电压、相电流和频率4个量,计算出初级电阻、初级漏感、次级电阻、次级漏感、气隙电感和铁损电阻.电机的特性分析表明,该方法真实有效,具有一定的参考价值.     

On the design of a single-sided linear induction motor for urban transit

Single-sided linear induction motor (SLIM) propulsion and wheel-on-rail support and guidance for urban transit has been developed in Canada and Japan. The maximum speed for urban transit is about 70 km/h, with the trains repeatedly performing powering, coasting, and braking operations within relatively short distances between stations. In the design of SLIM's operating under such conditions, we must take into account energy consumption as well as motor weight, input KVA, and performance characteristics. In this paper, we conduct a theoretical examination of such a SLIM design, estimating its performance characteristics in using space harmonic analysis. Energy consumption is reduced by decreasing the mechanical clearance. The flux density, then, should be a low value of from 0.5 T to 0.6 T. A motor length of from 2 to 2.5 m and pole pitch of about 300 mm are advisable.     

Decentralized adaptive backstepping stabilization of interconnected systems with input time delays in dynamic interactions

In this paper, we provide a solution to the problem by considering input time delays in dynamic interactions. Each local controller, designed simply on the basis of the model of each subsystem by using filtered transformation and standard backstepping technique, only employs local information to generate control signals. The robustness of decentralized adaptive controllers is established. It is shown that the designed decentralized adaptive backstepping controllers can globally stabilize the overall interconnected system asymptotically. The L₂ and L_∞ norms of the system outputs are also established as functions of design parameters. This implies that the transient system performance can be adjusted by choosing suitable design parameters. Copyright © 2011 John Wiley & Sons, Ltd.     

Investigation of the double input power converter with N stages of voltage multiplier using PSO-based MPPT technique for the thermoelectric energy harvesting system

This research work presents a thermoelectric energy harvesting system comprises of a double input DC-DC converter with maximum power point tracking (MPPT) technique under varying temperature conditions (VTCs). The converter has two inputs with N stages of diode-capacitor to boost the output voltage. It has the advantages of higher voltage gain and flexibility of power-sharing by both the independent sources. The perturb and observe (P&O)-based MPPT algorithm is an efficient and simple method to track the maximum power. However, the power-current (P-I) characteristics of the thermoelectric modules exhibit multiple peaks at VTCs; it fails to identify the global peak point (GPP) and gets track the local peak point. To overcome the drawback of the P&O technique, a particle swarm optimization (PSO)-based MPPT technique is implemented to track the GPP. A comparison is performed between the P&O and PSO technique in terms of MPPT tracking efficiency and oscillation around the maximum power point. From the acquired results of simulation and experiment, it is recommended that the PSO-based MPPT technique has furnished better overall performance.     

EXPERIENCE WITH DIRECT AND INDIRECT SEARCH METHODS APPLIED TO CAGE INDUCTION MOTOR DESIGN OPTIMIZATION

Abstract

In the present paper low cost cage induction motor design problem is approached using direct search methods, which do not require to calculate the derivatives of the function, and indirect method-a penalty function approach. Induction motor design is considered as a nonlinear, multivariable constrained optimisation problem with ampere conductors per meter, ratios stack length to pole pitch and stator slot depth to width, stator core depth, average air-gap flux density, and stator and rotor winding current densities as variables. The constraints are imposed on the thermal ratings of the machine and on performance indices- Results for same capacity motor with different optimization techniques are tabulated and compared.     

Basic Design Method for SPMSM Based on Air‐Gap Magnetic Flux Density Distribution Focusing on Image Magnetic Pole

This paper presents a basic design method for the surface‐mounted permanent magnet synchronous motor (SPMSM) for both distributed and concentrated windings. The design is based on the air‐gap magnetic flux density distribution focusing on the image magnetic pole. The calculus equation of the air‐gap magnetic flux density distribution is analytically derived by supposing the magnetic pole is located on the magnet surface and image planes. In this study, a three‐phase and double‐layer stator winding SPMSM that has a linear demagnetizing characteristic magnet, such as a ferrite or rare‐earth magnet is considered. From the required specifications and design conditions, the design target values of the parameters that appear in the voltages equations of the d–q axis coordinate system are calculated. Then, the relational equations for the torque constant, d‐axis inductance, copper loss, and the maximum current density are presented as a function of three design parameters under i_d = 0 control. They are the stator stack length, the number of coil turns in series in a phase, and the slot bottom length. Hence, this approach reduces the SPMSM basic design to the problem with these design parameters has to be solved. The proposed method makes it possible to address the concentrated winding as a special case of the distributed winding. The FEA results confirm the validity of the proposed basic design method for both distributed and concentrated windings.     

基于绕组函数法的大功率单边直线感应电机牵引特性研究

将麦克斯韦方程和绕组函数法相结合,得到单边直线感应电机(single linear induction motor，SLIM)的初级、次级基波和边端效应波绕组函数。由绕组函数理论计算出电感、运动电势系数，建立电压和磁链方程。由初、次级能量关系得到推力方程并进一步求解相关特性量。对不同工况的暂态和稳态特性进行分析。将大功率电机全过程中相电流、推力、效率的计算值与测量值进行比较。试验结果表明，绕组函数法能较合理地描述SLIM特性，具有一定实用性。     

DESIGN OPTIMIZATION OF CURRENT SOURCE INVERTER FED SQUIRREL CAGE INDUCTION MOTOR

ABSTRACT

This paper deals with the design optimization of current source inverter (CSI) fed squirrel cage induction motor. For this a set of ten independent variables is selected and seven objective functions are considered namely, the active material cost, operating cost, a mixed objective function of the active material cost and operating cost, torque pulsations, voltage across commutating capacitor, maximum commutation time of CSI and an integrated objective function. To visualize extreme performance for a particular objective function, the design is optimized considering only one objective function at a time. Finally an integrated objective function is proposed which is formed as a combination of all other objective functions with suitable weighting factors to suit optimum design for a particular application. In the task of design optimization the desired thermal, starting and normal operating performance are optimally met by imposing twelve suitable constraints. In this investigation the Sequential Unconstrained Minimization Technique (SUMT) with interior penalty function approach is used to optimize the design. In this method, Rosenbrock's method is used to achieve unconstrained minimization. The optimized design results of a 7.5 kW, delta connected CSI fed cage motor are given and discussed in detail.     

层叠滤波器的研究进展与分析

非线性滤波器可有效地处理脉冲噪声、斑点噪声或信号独立噪声,被广泛地应用在信号和图像处理领域中。层叠滤波器是一种逐渐兴起的非线性数字滤波器,它具有阈值分解和层叠性。由于确定层叠滤波器的正布尔函数的长度随变量的增加呈指数变化,层叠滤波器的优化设计成为该研究领域的技术难题,本文对国内外层叠滤波器的基础理论进行分析,从数学优化模型、统计特性、输出分布等几个角度进行了综合归纳和分析,力图为层叠滤波器的优化设计寻找突破点,加强此领域的研究力度。     

Simplified impedance broadband matching by the image parameter method: The RC case

The image parameter theory is now considered as outdated for filter design owing to the existence of very efficient optimization procedures for the effective behaviour of filters. Nevertheless, it allows one to exhibit very simple relations between the bandwidth and the values of the components. Hence it is ideally suited for the problem of impedance broiband matching where the bandwidth and some components are specified data. It is shown that it allows to make a straightforward distinction between well- and ill-conditioned problems. In the first case the problem is reduced to a one-dimensional optimization and an image parameter design provides very easily an equalizer optimal for all practical purposes. In the second case the values of the image parameter design provides excellent initial values for an optimization process. The method is applied here to the simplest problem, the RC load. In a separate paper it will be shown that it is easily extended to more complicated loads and the double-matching problem.     

采用外加剂提高混凝土的抗渗性和抗冻性

在水工结构和寒冷地区对混凝土的抗渗性、抗冻性的配合比设计提出了更高要求,不掺用外加剂很难满足抗渗性、抗冻性的要求,因此在混凝土的拌制过程中掺入外加剂,不但能提高混凝土的抗渗性、抗冻性,还能满足设计要求,并能取得良好的经济效益。     

Effect of the Selection of Input Voltage and Maximum Operating Flux Density of Different Core Material on the Optimum Design of Switching Power Converter

The effects of using different input voltage and different core material of different saturation flux density on the switching power converter weight minimization are presented. The design- oriented sensitivity analysis by perturbing the operating point, for example, the input voltage and the maximum flux density, reveals valuable design insights into the switching power converter global design optimization. A cost-effective computer-aided nonlinear programming (NLP) design technique is utilized for the minimum weight design. The new topology Cuk switching converter is taken as a demonstration example. Detailed loss and weight breakdowns as a function of the input voltage and the operating flux density are calculated for the optimum operation. Significant differences of the overall power converter performances are observed by using different input voltages and saturation flux densities.     

OPTIMUM DESIGN OF SMALL DISTRIBUTION TRANSFORMER USING ALUMINIUM CONDUCTORS

ABSTRACT

Design Optimization of distribution transformer of small KVA rating using aluminium conductors is considered as a nonlinear multivariable constrained programming problem. For this purpose a set of five independent design variables is identified and suitable constraints are imposed to meet the thermal and other performance requirements of the transformer. The various objective functions are formed in terms of cost of active material, capitalized cost of losses as the operating cost and the overall cost as the sum of these two. This is done to select most effective and appropriate optimized design for these types of transformers. The optimization is achieved through Rosenbrock's method of direct search in conjunction with the sequential unconstrained minimization Technique (SUMT). The optimized design results for a 25 KVA distribution transformer using aluminium conductors are presented along with the design results using copper as the winding material for different objective functions.     

Computer-aided design of stable recursive digital filters from magnitude specifications

This paper presents a method of designing one- and two-dimensional recursive digital filters making use of the properties of bilinear transformation of strictly Hurwitz polynomials. The result is a stable digital filter in both one- and two-dimensional cases, which requires no further testing for stability. The well known unconstrained minimization technique of Fletcher—Powell is used, making use of a transformation of optimization parameters to satisfy the mild constraints of stability. This method is considered to be more efficient on an overall basis than the existing l_p design technique of Maria and Fahmy. Nor does it rely on Deczky's theorem to ensure a stable filter which may sometimes lead to unstable solutions in the two-dimensional case. An example is provided illustrating the method.     

Maximum loadability of power systems using hybrid particle swarm optimization

The problem of voltage stability is one of the main concerns in the operation of power systems. There are different approaches to estimate the voltage stability of the system. One of these approaches is to find the margin from the current operating point to the maximum loading point of the system. Finding this maximum loading point can be formulated as an optimization problem. This paper utilizes the newly developed evolutionary particle swarm optimization in solving this optimization problem. Details of the implementation of the proposed method to two test systems (Ward-Hale 6-bus) and (IEEE 14-bus) are presented. The results are compared to those obtained by the widely used continuation power flow technique. Good agreement has been obtained proving the validity and applicability of the proposed method.     

Novel high step-up DC–DC converter with increased voltage gain per devices and continuous input current suitable for DC microgrid applications

This paper suggests a nonisolated noncoupled inductor-based topology for direct current (DC)–DC converters for DC microgrids. The proposed configuration profits from advantages like high step-up capability, continuous input current, simple structure, reduced normalized standing voltage (NSV) on switches/diodes, large gain per devices, common ground point between source-load, and maximum power point tracking (MPPT) capability. Both the switches (T₁, T₂) are turned on/off simultaneously, which minimizes the number of operational modes and simplifies the control strategy. These properties lead to a more compact, less expensive, and lighter topology. The operational modes and steady-state analysis as well as design considerations have been presented in detail. According to comparative analysis, the voltage conversion ratio per number of devices in suggested topology is higher than that of other similar topologies addressed in literature. The simulation results extracted from PSCAD/EMTDC software and the experimental outcomes obtained from laboratory-scale prototype confirm the effectiveness and correct performance of proposed topology.     

Coordinated design of PSS and TCSC to mitigate interarea oscillations

Thyristor controlled series compensator (TCSC) as a promising series flexible AC transmission system (FACTS) device is generally used for controlling the real power flow in transmission lines. It can increase the system stability as the complementary functionality by minimizing the power oscillations. The effectiveness of TCSC in its primary and supplementary applications depends on the selection of its optimal location and defining a proper input signal. In this paper, a new method based on the active power sensitivity approach is applied to find the optimal location of TCSC. In addition, Hankel singular values (HSVs) and right half plane-zeros (RHP-zeros) analyses have been proposed to find the most appropriate stabilizing input signal for the supplementary functionality of TCSC to damp out the interarea modes of oscillation. Finally, the optimal design of power oscillation damper (POD) and simultaneous coordinated design of power system stabilizer (PSS) and POD are implemented separately in a large-scale power system. The tuning problem of POD-TCSC parameters as well as the coordinated POD-TCSC & PSS are converted to a multi-objective optimization problem and solved using particle swarm optimization (PSO) algorithm. The performance of the proposed method has been validated through eigenvalue analysis and nonlinear time domain simulation in a 16-machine 68-bus test system. The simulation results show a satisfactory robust performance with an excellent capability in damping of local and interarea power oscillations.