电动汽车多车位WPT下沉式磁屏蔽系统研究

在电动汽车无线电能传输系统中,实现高效传输的同时减少磁泄漏一直是一个技术挑战。针对这一问题,本文提出了一种应用于多无线电能传输系统的下沉式屏蔽线圈结构,该结构在减小目标面漏磁的同时不会影响系统的传输效率。首先,提出了一种基于矢量磁位的矩形线圈磁场计算方法,通过此方法对系统目标面漏磁进行分析,为后续的磁泄漏优化提供了理论依据;其次,介绍了一种漏磁优化的方法,运用该方法得到满足要求的各线圈参数,为实现高效的无线电能传输提供了关键支持;最后,根据得到的线圈参数,研制了一套带磁屏蔽结构的双车位电动汽车无线充电系统,通过仿真和实验,让提出的屏蔽结构和方法的有效性得到了充分证实。结果显示,当系统输出功率恒定在4 kW时,所提出的屏蔽结构不仅使目标区域最大泄漏磁场降低了25%,且传输效率高达95%。

无线电能传输系统高效率低漏磁的全向环绕型有源磁屏蔽结构

在电动汽车无线电能传输系统(WPT)中,如何通过电磁屏蔽技术来降低WPT系统中的漏磁,同时维持较高的传输效率是一个难题。为此本文提出了一种全向环绕型有源磁屏蔽线圈结构来减少WPT系统中的漏磁。首先,分析了该结构的磁屏蔽工作原理以及设计思路,推导了该结构的数学模型;其次,根据本文线圈结构高效率低漏磁的特点,提出了一种线圈优化方法,得到了满足设计要求的线圈参数;最后,根据得到的线圈参数,搭建了一套基于所提线圈结构的WPT系统,并通过仿真和实验验证了该结构和方法的合理性。结果显示,在传输功率为4 kW时,本文提出的线圈结构在偏移0 cm时,目标面的最大漏磁为3.76μT,相比无屏蔽线圈结构降低了43.63%的漏磁,并且传输效率高达95.58%;在偏移10 cm时目标面的最大漏磁为6.03μT,仍符合漏磁安全标准,并且传输效率为92.92%,高于同尺寸无源屏蔽线圈结构和传统有源屏蔽线圈结构的传输效率。

无线充电系统电磁屏蔽与效率优化技术研究

在电动汽车无线电能传输系统中,磁屏蔽效果往往以牺牲传输效率为代价,如何减少磁泄漏的同时提高传输效率是一个难题。为此本文提出了一种新型强耦合磁屏蔽结构来减少系统磁泄漏。首先,提出了一种强耦合磁屏蔽线圈结构,基于提出的屏蔽线圈结构,分析了屏蔽线圈阻抗特性对系统漏磁与传输效率的影响;其次,给出了一种漏磁优化流程,运用提出的优化流程,得到了满足设计要求的各线圈参数;最后,根据得到的线圈参数研制了一套基于电动汽车带磁屏蔽结构的无线充电系统,通过仿真和实验验证了所提结构与方法的有效性。结果显示,提出的新型强耦合磁屏蔽线圈不仅使系统的磁泄漏有效降低了28%,且传输效率提升了近4%。

Structure and Oxidation Behavior of a Plasma Sprayed Yttrium Silicates Coated SiC-C/C with a Glass Outer Sealant from 1573K to 1873K

Different compositions of yttrium silicates coatings were deposited on SiC-C/C by plasma spraying and an outer borosilicate glass was applied on the yttrium silicates coatings surfaces. The structure of the multi-layer coatings was characterized by XRD and SEM analyses. High temperature oxidation behavior of the multi-layer coatings coated C/C composites was investigated. Results show that SiC/2SiO2 Y2O3/1.5SiO2 Y203/ SiO2 Y2O3/glass multi-layer coating has better high temperature oxidation resistance, protecting carbon/ carbon composites from oxidation at 1 773 K in air for 164 h with the weight loss of 1.65%. The oxidation weight loss of the coated C/C with time accorded with parabolic rule in the temperature range 1 573 K-1 873 K; and the corresponding oxidation activation energy of the coated carbon/carbon composites is 132.2 kJ/mol.

Thermal Fatigue Behavior of SiC/MBAS Glass Coated Carbon/Carbon Composites

The thermal fatigue behavior of C/C composites coated with the SiC/MBAS glass (MoSi2 particle-containing boron aluminosilicate glass) coating, prepared by the two-step process of the pack cementation and procoating-sintering, was investigated in present paper. The experimental results indicated that the SiC/MBAS glass coating had an excellent thermal shock resistance in air at temperature up to 1873 K. During quick thermal cycle between 1873K and room temperature in air, the decrease of mass and mechanical property of the coated C/C composites was all slight. After thermal cycle for 50 times, the mass loss of the SiC/MBAS glass coated sample was only 0.22%; additionally, the remaining ratio of strength and modulus was no less than 95.2% and 99.4%, respectively. The decrease of the mechanical property during the thermal cycle was primarily due to the damnification of the fiber/matrix interfaces and the oxidation of the coated samples with oxygen.

基于温度梯度缓冲的寒地地铁候乘空间温度区间研究

以沈阳理工大学地铁站候乘空间为例,依据气候缓冲梯度对严寒地区地铁候乘空间设计温度区间进行研究,提出修正建议温度值与温度区间,为提升寒地地铁候乘空间热舒适性提供参考依据。以沈阳理工大学地铁站为研究对象,采用现场实测和问卷调查的研究方法,研究冬季沈阳地铁候乘空间的热舒适情况,并将地铁站候乘空间分为出入口、站厅和站台3个空间进行研究,根据实测数据和设计规范调整温度上限和下限,求出建议温度值,分别得出3个修正后的中值温度和温度区间。在使用HDR指标证明沈阳冬季地铁候乘空间的热舒适时,利用3个空间的修正建议温度值和温度区间设计可行。

水热电沉积法生长Co_9S_8薄膜电极

采用水热电沉积法在泡沫镍基体上原位沉积Co_9S_8薄膜,并对其形貌、组成、结构和电化学性能进行表征和测试。结果表明,镍基Co_9S_8薄膜呈花瓣片状,并具有优异的电化学性能,其在电流密度为10mA/cm^2时,比电容可高达2538.7 F/g。即使电流密度扩大至50 mA/cm^2时,比电容依然可达1930.7 F/g。经过1000次循环(电流密度为20 mA/cm2),比电容仍可达为1825.2 F/g,电容保有率72.8%,经过1500次循环后,电容保有率61.4%。

Synthesis of LiFePO_4 in situ vapor-grown carbon fiber (VGCF) composite cathode material via microwave pyrolysis chemical vapor deposition

One of the most important factors that limits the use of LiFePO 4 as cathode material for lithium ion batteries is its low electronic conductivity.In order to solve this problem,LiFePO 4 in situ vapor-grown carbon fiber (VGCF) composite cathode material has been prepared in a single step through microwave pyrolysis chemical vapor deposition.The phase,microstructure,and electrochemical performance of the composites were investigated.Compared with the cathodes without in situ VGCF,the initial discharge capacity of the composite electrode increases from 109 to 144 mA h g-1 at a 0.5-C rate,and the total electric resistance decreases from 538 to 66.The possible reasons for these effects are proposed.