飞行控制用无刷直流电动机的电磁设计

 飞行控制中机电作动系统的发展是全电飞机的重要技术之一,而无刷直流电动机是其中的关键部件.采用钐钴永磁材料可以明显地减轻电机的质量和提高效率,该电机能在低惯量下输出高转矩,具有良好的快速响应能力.但电机体积主要受定子损耗引起的发热和温升的限制,与永磁材料的磁能积无关.另外,脉宽调制逆变器电源将使电机的铁损耗大大增加.根据逆变器电源的特点,结合电机的技术指标和对功率/质量、峰值转矩/转子惯量等要求,提出了该电机设计时应考虑的主要电磁因素.     

稳定悬浮状态下无轴承开关磁阻电机电感特性

针对二维有限元和磁链法计算无轴承开关磁阻电机(Bearingless switched reluctance motor,BSRM)电感特性的局限性,建立了BSRM稳定悬浮时的三维有限元模型,采用双标量磁位法计算得到其磁场分布,应用一种仅需计算非线性系统能量增量即可计算电感的增强型能量增量法,计算其绕组电感.以-7.5 kW,12/8结构的BSRM为例,简单比较了双标量磁位法与二维有限元法、矢量磁位法和棱边有限元法分别求解BSRM磁场时的计算规模和平均计算时间,说明了双标量磁位法在大规模计算场合的优越性;研究了电感与转子径向位移的关系;计算获得了样机处于稳定悬浮状态下的主、悬浮绕组电感;研究了端部效应对电机磁场分布和绕组电感的影响.通过实验验证了电感计算的准确性,为优化设计和精确控制该类电机奠定了基础.     

附加场强度对低工况AF-MPDT性能的影响

附加磁场强度与位形是大功率磁等离子体动力推力器(Applied Field Magnetoplasmadynamic Thruster, AF-MPDT)重要工作参数之一。为验证附加磁场强度对低工况下AF-MPDT性能的影响,采用北京控制工程研究所联合北京航空航天大学研制的100 kW级AF-MPDT原理样机,利用推力靶测量系统进行高温震动环境下的推力测量,针对不同附加磁场强度(30～230 mT)下的推力器开展中低功率性能研究实验。实验结果表明,在一定范围内,增加磁场强度可提升低工况下推力器推力、比冲、放电电压及效率等性能指标,并且放电电流越大,性能提升效果越明显。分析表明,低工况下AF-MPDT推力、比冲与磁场强度的平方根呈线性关系;推力器放电电压与磁场强度呈线性关系;推力器效率随磁场强度增强而增加,最终达到相应工况下的极限。     

太阳10.7 cm射电流量中期预报模型研究

太阳活动指数中期预报一直是空间环境业务预报的难点之一. 本文在自回归方法模型的基础上, 利用太阳活动区面积、位置等参数与10.7cm辐射流量之间的定量关系, 根据活动区面积衰减规律, 建立了一个基于活动区参数及演化规律的改进型太阳活动指数中期预报模型. 通过对预报测试实例分析发现, 在日面出现较大活动区导致F10.7迅速增长并超过历史数据峰值的情况, 在日面活动区消亡导致指数突然出现平静期的情况, 新模型的预报准确性相比自回归模型有很大提高, 预报的平均相对误差下降约5%~9%. 由此可见, 新模型在某些特定条件下提高了原有模型的精度. 该研究为提高业务型太阳10.7 cm射电流量中期预报模型的预报精度奠定了基础.     

六相永磁容错轮毂电机多物理场综合设计方法

针对电动装甲车用轮毂电机工况复杂多变,发热严重的问题,通过对电机所涉及各物理场之间关系的分析,提出了一种永磁容错轮毂电机多物理场设计方法。利用该方法对一台电动装甲车用额定功率50 kW,最高转速6 000 r/min六相永磁容错轮毂电机进行了综合设计。在电机结构初步设计基础上,通过电磁-应力耦合分析,在兼顾电磁性能和转子强度的情况下对转子隔磁磁桥进行优化设计;通过电磁-温度耦合分析计算了电机内各区域温度分布,并对永磁体在极限温度下的退磁进行了校核;通过应力-温度耦合设计完成了转子与护套的最大应力计算,校核了护套厚度及过盈量。仿真结果表明,基于多物理场综合设计方法得到的电机能同时满足电磁性能、温度限制以及机械强度的要求,电机可靠性得到了提高。      

Comparison of GPS-TEC measurements with NeQuick2 and IRI model predictions in the low latitude East African region during varying solar activity period (1998 and 2008–2015)

This paper examines the performances of NeQuick2, the latest available IRI-2016, IRI-2012 and IRI-2007 models in describing the monthly and seasonal mean total electron content (TEC) over the East African region. This is to gain insight into the success of the various model types and versions at characterizing the ionosphere within the equatorial ionization anomaly. TEC derived from five Global Positioning System (GPS) receivers installed at Addis Ababa (ADD, 5.33°N, 111.99°E Geog.), Asab (ASAB, 8.67°N, 116.44°E Geog.), Ambo (ABOO, 5.43°N, 111.05°E Geog.), Nairobi (RCMN, ?4.48°N, 108.46°E Geog.) and Nazret (NAZR, 4.78°N, 112.43°E Geog.), are compared with the corresponding values computed using those models during varying solar activity period (1998 and 2008–2015). We found that different models describe the equatorial and anomaly region ionosphere best depending on solar cycle, season and geomagnetic activity levels. Our results show that IRI-2016 is the best model (compared to others in terms of discrepancy range) in estimating the monthly mean GPS-TEC at NAZR, ADD and RCMN stations except at ADD during 2008 and 2012. It is also found that IRI-2012 is the best model in estimating the monthly mean TEC at ABOO station in 2014. IRI show better agreement with observations during June solstice for all the years studied at ADD except in 2012 where NeQuick2 better performs. At NAZR, NeQuick2 better performs in estimating seasonal mean GPS-TEC during 2011, while IRI models are best during 2008–2009. Both NeQuick2 and IRI models underestimate measured TEC for all the seasons at ADD in 2010 but overestimate at NAZR in 2009 and RCMN in 2008. The periodic variations of experimental and modeled TEC have been compared with solar and geomagnetic indices at ABOO and ASAB in 2014 and results indicate that the F10.7 and sunspot number as indices of solar activity seriously affects the TEC variations with periods of 16–32?days followed by the geomagnetic activity on shorter timescales (roughly periods of less than 16?days). In this case, NeQuick2 derived TEC shows better agreement with a long term period variations of GPS-TEC, while IRI-2016 and IRI-2007 show better agreement with observations during short term periodic variations. This indicates that the dependence of NeQuick2 derived TEC on F10.7 is seasonal. Hence, we suggest that representation of geomagnetic activity indices is required for better performance over the low latitude region.     

December 2006 solar extreme events and their influence on the near-Earth space environment: “Universitetskiy-Tatiana” satellite observations

The Russian microsatellite “Universitetskiy-Tatiana” was launched on Jan. 20, 2005 and was both a scientific and educational mission. Its two main aims were declared as: (1) monitoring of the energetic particles dynamics in the near-Earth space environment after solar events and during quiet times, (2) educational activities based on experimental data obtained from the spacecraft. In this paper observations acquired during Dec. 5–16, 2006, known as “Solar Extreme Events 2006”, were analyzed. The “Universitetskiy-Tatiana” microsatellite orbit permits one to measure both solar energetic particle dynamics, variations of the boundary of solar particle penetration, as well as relativistic and sub-relativistic electrons of the Earth’s outer radiation belt during and after magnetic storms. Both relativistic electrons of the Earth’s outer radiation and solar energetic particles are an important source of radiation damage in near-Earth space. Therefore, the presented experimental results demonstrate the successful application of a small educational spacecraft both for scientific and educational programs.     

一种基于太阳自转轴观测角的新型天文导航方法

针对太阳探测器,提出一种基于太阳自转轴观测角的新型天文导航方法,通过光谱仪测量太阳圆盘面边缘上两组连线互相垂直点的速度差值,建立速度差值与太阳自转轴观测角的数学模型,并以该观测角作为量测量来提供探测器的位置信息。仿真结果表明:相较于传统以太阳视方向作为量测量的导航方法,以太阳自转轴观测角作为量测量的新型天文导航方法的导航精度提高了17.4%。此外,还分析了测速敏感器精度、滤波周期和轨道倾角对导航性能的影响,为深空探测自主导航提供了新的理论与方法。     

小天体探测器电源系统方案设计及仿真

研究了小天体探测器在深空特殊环境下电源系统所面对的问题,提出了全调节母线能量直接传递的电源系统方案。根据探测器的轨道特性,分析了探测器在飞行过程中环境条件和不同负载等对电源系统的影响,考虑光照条件和峰值功率之间的关系,基于能量平衡的原理,对探测器的电源系统进行分析、设计。最后,通过数学仿真验证了方案设计的合理性。     

产生匀强磁场的圆柱形线圈组设计方法

在精密测量和航空航天领域,原子陀螺仪、原子磁强计等对线圈产生磁场的均匀度有很高的要求,而传统的亥姆霍兹线圈磁场均匀度较差,难以满足应用需求。为了设计产生高均匀度磁场的线圈组,基于线圈轴向磁场的泰勒展开式,提出了任意线圈数的圆柱形线圈组参数的计算方法,并给出了9线圈以内的线圈参数,分析了磁场均匀度、线圈尺寸、线圈最大安匝比随线圈个数的变化趋势。结果表明随着线圈个数的增加,均匀区面积几乎线性增大,9线圈组磁场均匀度优于0.01%的区域面积约为亥姆霍兹线圈的30倍。在要求各个线圈由整数匝线圈组成且各匝线圈电流相同的情况下,提出了一种线圈安匝比取整的方法,并给出2~9线圈组的安匝比取整结果,计算结果表明相同线圈个数下设计的线圈组产生磁场的均匀度优于已有文献。以5线圈组为例,对实际线圈组制作工艺产生的误差进行了仿真分析,仿真结果表明,考虑误差的情况下,设计的尺寸和磁场也满足原子陀螺仪、原子磁强计等的实际要求。