基于MRAS的新型永磁同步电机的速度辨识方案

速度辨识一直是永磁同步电机无速度传感器控制系统中的一个核心问题,本文以永磁同步电机本身为参考模型,变换数学模型构造并联模型,并由转矩和转速的基本的机械运动方程和转矩方程推导出速度辨识率,结合模型参考自适应控制理论得到速度辨识方案。本方案控制过程简单,对电机参数不敏感,并将其应用在永磁同步电机矢量控制系统当中,仿真得到的结果验证了本方案的正确性和可行性,同时,与基于POPOV理论的模型参考自适应方案的仿真结果进行比较,分析本方案的优劣。     

相似绕组的电感比例关系

提出了在缓变及磁介质均匀分布于整个空间且磁导率不随磁场变化的条件下相似绕组之间的感应系数关系式。两相似绕组的电感比值与对应边长之比和线匝密度之比有确定的关系。电感比值还可变换为与绕组体积之比,线材体积之比,填充系数之比,导线截面之比和总匝数之比相关的表述。     

磁力机械研究综述

回顾了磁学理论和应用的历史发展;较系统地介绍了现代工程磁学应用的一个重要分支——磁力机械的种类、发展过程、应用现状和一些典型的机构;列出了适用于磁力机械设计的各种设计方法,分析了这些方法的优缺点和适用范围;展望了磁力机械未来的研究和应用发展前景。     

Challenges of short magnet design

The desire to improve patient comfort and acceptance of high field magnetic resonance imaging (MRI) systems results in new-approaches to magnet and other critical MRI component design. One such approach, based upon an anatomical field of view analysis, is presented in this paper. The approach is utilized to define imaging volume requirements for short, high field, solenoid magnet designs that maintain whole body imaging capability. A short magnet design with excellent magnetic field homogeneity is presented accordingly. Combined with a novel flared gradient coil the overall system achieves improvements in openness.     

采用改进遗传算法的新型阀用电磁机构的优化设计

遗传算法用于元件的设计和选型是目前研究的热门课题。采用改进的遗传算法对文献[1]中提出的新型节能电磁换向阀的电磁机构进行了优化设计 ,给出了优化设计数学模型及优化结果 ,并对采用一般遗传算法和改进遗传算法进行优化设计获得的结果进行了比较 ,比较结果表明 ,采用改进后的遗传算法对于新型阀用电磁机构的优化设计具有寻优精度高 ,寻优速度相对较快的优点。     

永磁体铸机金属液流场特征分析

利用数值模拟对不同磁场条件下的永磁铸机金属液流场特征进行了模拟分析 ;揭示了金属液流场与永磁体极数、磁极排布方式、磁场旋转速率以及永磁体螺旋式排布之间的关系 ,为永磁铸机的优化设计提供了参考依据     

Busbar arcs at large fusion magnets: Conductor to feeder tube arcing model experiments with the LONGARC device

Electric arcs moving along the power cables (the so-called busbars) of the toroidal field (TF) coils of ITER may reach and penetrate the cryostat wall. Model experiments with the new LONGARC device continue the VACARC (VACuum ARC) experiments that were initiated to investigate the propagation and destruction mechanisms of busbar arcs in small scale [1]. The experiments are intended to support the development and validation of a numerical model. LONGARC overcomes the space limitations inside VACARC and allows also for advanced 1:3 (vs. ITER full scale) model setups. The LONGARC device and first results are presented below.     

Final design of the Switching Network Units for the JT-60SA Central Solenoid

This paper describes the approved detailed design of the four Switching Network Units (SNUs) of the superconducting Central Solenoid of JT-60SA, the satellite tokamak that will be built in Naka, Japan, in the framework of the “Broader Approach” cooperation agreement between Europe and Japan.The SNUs can interrupt a current of 20 kA DC in less than 1 ms in order to produce a voltage of 5 kV. Such performance is obtained by inserting an electronic static circuit breaker in parallel to an electromechanical contactor and by matching and coordinating their operations. Any undesired transient overvoltage is limited by an advanced snubber circuit optimized for this application. The SNU resistance values can be adapted to the specific operation scenario. In particular, after successful plasma breakdown, the SNU resistance can be reduced by a making switch.The design choices of the main SNU elements are justified by showing and discussing the performed calculations and simulations. In most cases, the developed design is expected to exceed the performances required by the JT-60SA project.     

电梯曳引机型式试验问题探讨

叙述了电梯曳引机型式试验中存在噪声,永磁体失磁,制动器等方面的问题,分析了产生问题的原因,结合相关国家标准对试验方法进行了探讨,并提出了可行的解决问题的办法。     

电动伺服系统电流环设计

为了构成高性能的电动伺服系统电流环,论文介绍了永磁同步电动机矢量控制的原理和数学模型,然后根据系统动态性能的要求,设计并选择调节器的类型。仿真结果表明,所设计的电流环具有很高的电流跟踪能力,为实现高性能电动伺服系统奠定了基础。