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71.
一种新颖的电磁式同步电机力矩控制方案 总被引:2,自引:1,他引:2
对同步电机直接力矩控制作了进一步的研究,从理论上分析同步电机转矩的产生,并将直接力矩控制思想延伸到电磁式同步电机,讨论了电磁式同步电机直接力矩控制的实现,仿真分析了电磁式同步电机直接力矩控制系统,并阐述了电磁式同步电机直接力矩控制方案较永磁同步电机方案具有的优点;定于磁链幅值不受转于磁链大小的限制,转矩-力矩角曲线线性度更好,转矩变化更快,动态性能更优;转子信号可测,无需复杂的运算和额外的装置辨识初转子磁极位置,仅靠转子激磁电流变化,从定子感应电势即可得到转子位置。此外,采用直接力矩控制更易于实现电机系统的无速度传感器运行。仿真结果表明了系统的可行性和的动态性能。 相似文献
72.
Detailed Design of a High Speed Switched Reluctance Starter/Generator for More/All Electric Aircraft 总被引:1,自引:0,他引:1
The basic concepts and advantages of more/all electric aircraft (M/AEA) are briefly addressed. The combined starter/generator (CS/G) system is introduced as a key technology to enable M/AEA. Some important performance requirements for CS/G system are obtained. Based on these requirements, a high speed switched reluctance machine (SRM) is designed to operate as a starter/generator. The entire design process is mainly divided into two stages: electromagnetic design and thermal design. In electromagnetic design stage, the electromagnetic structure and dimensions of the machine and the number of phase winding turns per pole are obtained; the topology and main technical details of the converter are briefly introduced as well. In thermal design stage, a liquid-cooling system is designed based on the thermal analysis of the machine. In the end, the performances of the designed SRM are basically verified by simulation. To get high performances, the exciting angles are optimized in two different operating modes respectively, and the optimized performances in the motoring mode are given as well. 相似文献
73.
The variable geometry supersonic inlet tends to decrease the throat area to reduce the Mach number upstream of the terminal shock, so as to reduce the flow loss. However, excessive Internal Contraction Ratio(ICR) exposes the inlet to a greater risk of unstart, which inevitably results in a process of increasing the throat area to aid the inlet restart. In the above throat regulation process, the inlet undergoes the start, unstart, and restart states in turn. In order to reveal the flow structure... 相似文献
74.
固体火箭发动机喷射物中的熔渣是航天器防护和空间碎片风险评估关注的对象之一。文章首先介绍国外熔渣建模试验数据及理论模型,主要有NASA熔渣模型、MASTER2005熔渣子模型(以下简称MASTER模型)和麻省理工大学林肯实验室的MIT/LL熔渣模型;再利用NASA和MASTER模型分析熔渣尺寸-数量和质量特性。MASTER模型给出的熔渣数量和质量均低于NASA模型;且MASTER模型认为约91.8%的熔渣尺寸处于25~200 mm区间;尺寸大于250 mm的熔渣质量占熔渣总质量的88%,但其数量只占熔渣总数量的6.3%。以上研究结果为进一步分析熔渣对空间碎片环境的影响奠定了基础,对我国自主开展熔渣模型研究也有一定的参考价值。 相似文献
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C-dump变换器的发电运行特性研究 总被引:1,自引:1,他引:0
介绍了一种可用于无刷起动/发电双功能系统的变换器拓扑--C-dump变换器,分析了其发电运行的基本原理。C-dump变换器发电运行时存在电机相电流利用主经低、这大的问题。为克服上述缺点,提出了一咎改进型Cdump变换器拓扑。文中对采用这种改进型变换器的发电系统的最低工程转速限制和系统发电特性进行了详细的讨论,分析了发电系统的输出电压及效率与转速的关系。研究结果表明,采用改进型C-dump变换器的发 相似文献
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78.
The hysteretic behavior and nonlinearity of the equivalent material coefficient of macro fiber composites (MFC) under staircase input conditions are investigated using the Preisach model. Based on a database of first order reversal curves, formulas are derived to predict the hysteresis of strain output and nonlinearity of the equivalent piezoelectric coefficient of MFCs. Formulae are verified by comparing the predicted strains with the measured strains of three MFC specimens, which are driven by a random sequence of staircase voltage inputs. The coefficients obtained by the formulae and experimentation coincide. Further results indicate that the equivalent piezoelectric strain coefficient depends greatly on the value of drive voltage across the entire input range, and the coefficient is asymmetric across the negative and positive input ranges. Deflection testing of an MFC composite cantilever demonstrates the importance of taking the nonlinearity of the equivalent piezoelectric coefficient into consideration in the application of actuation. 相似文献
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