Novel Sensorless Vector Control System of Induction Machine Based on Flux Observer in Field Weakening

A speed-sensorless vector control system for induction machines （IMs）is presented, According to the vector control theory of IMs, the rotor flux is estimated based on a flux observer,and the speed is estimated through the method of q-axis rotor flux converging on zero with proportional integral regulator, A 0.75 kW,50 Hz,two-pole induction machine was used in the simulation and experimental verification, The simulation model was constructed in Matlab. A series of tests were performed in the field weakening region, for both no-load and loaded operation. The estimated speed tracks the actual speed well in the based speed region and field weakening region （ 1 per unit value to 4 per unit value）. The small estimation error of residual speed is due to the existence of slip.     

The need to know and to understand in Maslow＇s basic needs hierarchy

Despite the fact that the Maslow＇s hierarchy of basic needs has been vastly applied in literatures, a majority of resources has neglected to take the need to know and to understand into account. Moreover, there is a wide disagreement in the rest of resources in situation of that need. This article attempts to show that （1） Maslow has had faith in that need as a basic need; and （2） even though Maslow has not explicitly mentioned the situation of this need in his hierarchy, it is possible to find its situation through implications of Maslow＇s writing and other researchers＇ findings.     

极低速驱动用直流电机电刷短路系数的算法

When a direct-current （DC） machine runs at extremely low speed or standstill, the reduction in the armature resistance and the armature flux linkage due to the short circuited coils by the brushes on the commutator should not be neglected. Taking this reduction effect into account, the average values of the reduction coefficients relate to the machine parameters in complicated forms. In this paper, an effective algorithm for the precise computation of the average values of these reduction coefficients is proposed. Furthermore, in the algorithm, the effect of the insulation thickness between the commutator segments and the multiplicity of the wave winding are considered for the first time. The proposed algorithm can also be accommodated into the computer-aided design （CAD） of a DC machine, which normally runs at extremely low speed or standstill.     

Learning in the workplace for garage mechanics and technicians

Employees in technical firms, like garages, need more and more formations. Due to the very fast innovation in technology, lifelong learning is a real need for these labour forces. On the other hand, there are the needed formations very specialized and expensive. Another problem employers faced in these economical sectors in Western Europe is the lack of candidates. Also in secondary education schools, the wide interest for these formations is decreasing. One of the factors causes this problem is that schools don＇t have enough money for investing in new and high-tech machines. Therefore two interreg projects were submitted and approved for financing. Interreg is an initiative of the European Union meant for the permanent development of the ＂European Space＂. The third phase of interreg means enhancing the economic and social cohesion within the European Union. In this paper, we describe two successful projects, namely Autoweb and V@K, which try to help employers, employees, schools and students to keep up with the high-tech innovations with a workplace-based e-learning program.     

Application of direct torque control to electric screw presses for speeding up torque response and reducing starting current

Fast response and stable torque output are crucial to the performance of electric screw presses. This paper describes the design of a direct torque control （DTC） system for speeding up torque response and reducing the starting current of electric screw presses and its application to the J58K series of numerical control electric screw presses with a dual-motor drive. The DTC drive system encompasses speed control, torque reference control, and switching frequency control. Comparison of the DTC dual-AC induction motor drive with corresponding AC servo motor drive showed that for the J58K-315 electric screw press, the DTC drive system attains a higher maximum speed （786 r/min） within a shorter time （1.13 s） during a 250 nun stroke and undergoes smaller rise in temperature （42.0 ℃） in the motor after running for 2 h at a 12 min-1 strike frequency than the AC servo motor drive does （751 r/min within 1.19 s, and 50.6 ℃ rise）. Moreover, the DTC AC induction motor drive, with no need for a tachometer or position encoder to feed back the speed or position of the motor shaft, enjoys increased reliability in a strong-shock work environment.     

Semi On-line Scheduling Problem for Maximizing the Minimum Machine Completion Time on mIdentical Machines

1　Introduction　In this paper, we consider a semi on line version onm identical machines M1, M2, …, Mm (m ≥3 )where the processing time of the largest job is knownin advance. A list (j1, j2, …, jn ) of jobs withprocessing times p1, p2, …, pn is given on line,which means we get the jobs one by one but both thetotal number of jobs that need to be scheduled and thesize of the jobs are not previously known. Theprocessing time of job ji becomes known only whenji-1 has…     

Tribology Performance and Adhesive Strength Evaluation of TiAlSiN Coating

Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAlSiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch test were calculated and the values are 30.84 MPa and 4.98 MPa respectively. The average friction coefficients of TiAlSiN coating against 2Cr12Ni4Mo3VNbN steel are 0.70 (sliding speed 50 m/min), 0.63 (sliding speed 100 m/min), and 0.81 (sliding speed 150 m/min). The elements diffusion was analyzed by EDS. Al and Si element of coating material diffuse to the steel disc, except Ti element. The oxidation decreases with the increase of sliding speed, but the adhesion increases with the increase of sliding speed. More Al element diffuses to the steel disc at the high sliding speed, but the diffusion of Si element keeps almost constant at different sliding speeds.     

Regulation law of turbine and generator in organic Rankine cycle power generation experimental system

In the performance experiment of organic Rankine cycle power generation experimental system, the loadresistance-regulation method is one of the most important regulation methods. However, the regulation law has not been clear enough to guide the experiment, which is unfavorable to the experimental research on organic Rankine cycle. In this paper the regulation law of turbine and generator by the load-resistance-regulation method is studied theo- retically and experimentally. The results show that when the thermal cycle parameters keep constant, the turbine speed increases with the increase of load resistance and there is a maximum value of transmission-generator efficiency with the variation of the turbine speed; when the turbine speed and generator speed keep constant, the transmissiongenerator efficiency decreases and gradually tends to zero with the increase of load resistance.     

Multi-core based parallel computing technique for content-based image retrieval

In this paper, we propose a parallel computing technique for content-based image retrieval （CBIR） system. This technique is mainly used for single node with multi-core processor, which is different from those based on cluster or network computing architecture. Due to its specific applications （such as medical image processing） and the harsh terms of hardware resource requirement, the CBIR system has been prevented from being widely used. With the increasing volume of the image database, the widespread use of multi-core processors, and the requirement of the retrieval accuracy and speed, we need to achieve a retrieval strategy which is based on multi-core processor to make the retrieval faster and more convenient than before. Experimental results demonstrate that this parallel architecture can significantly improve the performance of retrieval system. In addition, we also propose an efficient parallel technique with the combinations of the cluster and the multi-core techniques, which is supposed to gear to the new trend of the cloud computing.     

Parallel Spectral-Domain Optical Coherence Tomography for Non-Scattering Object Imaging

The parallel spectral-domain optical coherence tomography(PSDOCT) is described for high-speed optical coherence tomography(OCT) without lateral scanning. In this setup, the self-elimination of auto-correlation(AC) interference algorithm was used for eradicating the AC interference and ghost images. However, when performed in free space OCT, this algorithm still generated a weak DC component. The algorithm was improved by adding the background intensity part to compensate for the mutual interference between object and reference arms. The results demonstrate that the DC component can be eradicated. Compared with conventional OCT and complex Fourier-domain optical coherence tomography, the advantages of PSDOCT with the improved algorithm in free space are that it has no moving parts to generate consecutive phase shift, the structure of the object can be reconstructed immediately and automatically, and the speed is approximately 16 times faster than those of the other two in the same case.     

场路耦合有限元仿真在电机类课程教学中的应用研究

利用JMAG-Studio软件建立永磁电机的场路耦合的有限元模型,计算并分析永磁电机的空载和负载时瞬态特性,直观地展示电机的电流、反电动势、磁通密度、转矩等性能,并制作成基于电机转子旋转的动画,帮助学生深入理解电机的基本概念和知识,提高电气自动化类专业的电机类课程的教学效果。     

新型缝纫机用永磁直流电动机驱动电路设计

介绍一款缝纫机用永磁直流电动机驱动电路设计。该缝纫机具有良好的起动、调速和制动性能,通过脚踏板控制缝纫机即动即停。本驱动电路设计很好地解决了离合器电动机电能浪费的缺点,具有较好的应用价值。     

基于ICL7135的直流电参数测量仪设计

以Altera公司的CPLD芯片为直流电参数测量仪核心,以ICL7135芯片为直流电参数采集电路核心,所设计的监测仪能够实现对直流电压/电流的并行采样,电路结构简单、AD转换精度高、解决了分时切换方式下监测数据丢失问题。     

用Protel 99se仿真求解直流电路

Protel 99se是目前国内使用非常广泛的电路设计软件.用Protel99se仿真求解直流电路问题,可以通过设置仿真分析对话框,然后运行仿真来进行.并且相对于其他电路CAD(计算机辅助设计)软件,可以一次性得到直流电路全部解.这种方法的现实意义在于:既可以代替传统的电路分析方法来求解直流电路,又使得电路工程技术人员在调试和维修实际电路中需要获得有关电路直流数据以进行分析研究时,多了一条可行的途径.     

Study of a GaAs MESFET model with ultra-low power consumption

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Multi-physics coupling field finite element analysis on giant magnetostrictive materials smart component

This study presents a new method to solve the difficult problem of precise machining a non-cylinder pinhole of a piston using embedded giant magnetostrictive material （GMM） in the component. We propose the finite element model of GMM smart component in electric, magnetic, and mechanical fields by step computation to optimize the design of GMM smart component. The proposed model is implemented by using COMSOL multi-physics V3.2a. The effects of the smart component on the deformation and the system resonance frequencies are studied. The results calculated by the model are in excellent agreement （relative errors are below 10%） with the experimental values.     

机床电气线路电气故障排除的教学策略

在机床电气控制技术维修实训教学中,机床控制线路电气故障模块是重点,也是教学难点。结合自身实践经验和机床电气控制技术维修认识,采取了三步走的方式,就机床线路电气故障模块方面的实训教学方法加以探讨,为职业院校机床电气控制线路维修的教学提供参考和借鉴。     

电机实验中稳恒负载的实现

在电机实验中,转矩和转速的测试是非常关键的.转矩和转速的测试与负载有直接关系.在大多数电机实验中,负载是利用直流发电机接电阻或者是利用交流异步电机的能耗制动来实现的,也有使用电磁涡流制动器来实现的,这3种负载的转矩都是随转速变化的,这使转矩和转速的测试很不方便.针对这种情况,文章采用磁粉制动器作为负载,实验中发现磁粉制动器的转矩随着转速变化也有变化.为此,该文在磁粉制动器的励磁回路中设计了一闭环调节器,实现了稳恒负载.这给电机实验带来了很大的方便.     

全桥DC／DC（H桥）变换电路的设计与实现

在对桥式可逆斩波电路作出理论分析的基础上,建立基于MATLAB／Simulnk／PowerSystem工具箱的桥式可逆斩波电路的仿真模型,给出了电阻电感性负载及电动机负载时的仿真结果,并对其进行分析,同时也验证了本文所建模型的正确性．