电动车用永磁同步电机转子偏心对电磁力影响分析

针对电动车用永磁同步电机转子偏心问题,对偏心对电磁力的影响进行研究.通过解析法和有限元法建立电机偏心电磁力以及不平衡磁拉力模型,分析静动态偏心对电磁力的影响,得出静动态偏心会增加±1阶电磁力成分,并分别产生0Hz和f/p的不平衡磁拉力,且不平衡磁拉力成分随偏心率呈线性变化.这就为分析电动车用电机的振动和噪声激励源奠定了基础.     

基于多场耦合技术的永磁同步电动机散热分析

利用英特工程仿真技术公司开发的一套电动机专用的耦合分析接口软件INTESIMETFMotor,对电动汽车所用永磁同步电动机进行电磁-热-流体三场耦合分析,将电磁-热-流体三场耦合与传统解耦简化模型的分析结果进行对比,以验证热流双向耦合的有效性.结果表明,单向耦合不能够保证温度的连续性和能量守恒,达不到真正的热平衡,因而需要进行热流双向耦合.     

永磁同步电机飞轮储能系统充放电控制策略

针对飞轮储能系统(FESS)转动惯量大、采用传统矢量控制算法启动时在零速附近容易出现转速震荡的问题,提出了一种新的电机控制方法。该方法用理论计算转速替代模型参考自适应(MRAS)算法的观测转速,并用给定电流替代反馈电流对耦合项进行计算,减小电机转速振荡。在FESS放电时,需要根据负载所需功率调整电机输出功率,针对此问题,采用一种以维持直流母线电压恒定为目标的电机控制方法,同时在FESS投入工作前,用电机当前转速作为传统MRAS算法PI控制器积分项的初始值,加快了MRAS无速度算法的收敛速度。仿真和实验结果表明,与传统控制方法相比,所提出的控制算法能减小电机启动时在零速附近的转速振荡,维持FESS放电时负载的正常工作,保证FESS快速可靠地进行状态切换。     

A metal-organic framework based on Co(II) and 3-aminoisonicotinate showing specific and reversible colourimetric response to solvent exchange with variable magnet behaviour

A versatile metal-organic system consisting of Co-based compounds that show reversible transformations between a 3D metal-organic framework (MOF) of {[Co(μ-3isoani)₂]·DMF}_n (1) formula (where 3isoani = 3-aminoisonicotinato and DMF = dimethylformamide) and a 0D monomeric [Co(3isoani)₂(H₂O)₄] (2) complex is reported. These 1 ? 2 transformations, triggered by the exposure of the MOF and the monomer-based compound to H₂O and DMF, respectively, involve colour changes from purple (in MOF 1) to light brown (in monomeric complex 2), which imbues the system with colourimetric sensing capacity towards these solvents. Despite the high reactivity of the MOF in contact with water, it presents good thermal stability and permanent porosity with a remarkably high CO₂ capture capacity at room temperature (3.35 mmol/g), which is further analysed by in situ single-crystal X-ray diffraction. Experimental magnetic properties and CASSCF/NEVPT2 calculations of all compounds reveal distinct slow magnetic relaxations for 3D and 0D compounds.     

1⁃苯基⁃3⁃甲基⁃4⁃苯甲酰基⁃5⁃吡唑啉酮镝(Ⅲ)配合物的晶体结构、磁性及理论分析

采用缓慢挥发法合成了一例单核镝配合物[Dy(pmbp)3(H2O)2]·CH3CN(1),(Hpmbp=1?苯基?3?甲基?4?苯甲酰基?5?吡唑啉酮)。单晶X射线衍射数据表明镝离子与3个pmbp-配体和2个H2O分子配位,形成八配位的扭曲四方反棱柱构型。磁性测试表明配合物1在加场下可以表现出慢的磁弛豫行为,其有效能垒为42 K。通过理论计算得出了配合物1的磁易轴方向,并解释了其磁学性能。磁构关系研究分析了pmbp-配体的共轭效应对配合物1磁各向异性的影响。     

高配位3d过渡金属单离子磁体磁各向异性研究

单离子磁体(SIMs)因其磁性双稳态和慢弛豫机制而在高密度信息存储、量子计算和分子自旋电子学等方面具有潜在的应用价值。其中3d过渡金属单离子磁体(3d?SIMs)磁构关系较为简单且易于分析,因此得到了众多研究者的关注。目前文献上报道的大多数3d?SIMs通常具有较低的配位数,而对于高配位(七配位和八配位)的3d?SIMs缺少深入而系统的研究。我们结合近年来的研究成果,从磁各向异性的基本性质、实验表征和理论计算3个方面出发,对高配位3d过渡金属单离子磁体的配位环境、磁各向异性和慢磁弛豫行为进行了综述,分析了配位构型和配位原子等配位环境对高配位3d过渡金属单离子磁体磁各向异性的影响,为高配位3d过渡金属单分子磁体的设计与调控提供思路。     

A Mixed Valence CoIICoIII2 Field-Supported Single Molecule Magnet: Solvent-Dependent Structural Variation

One-pot reaction of the Schiff base N,N’-ethylene bis(salicylaldimine) (H₂L), CoCl₂.6H₂O, and [Ph₂SnCl₂] in acetone produces the mixed valence Co^IICo^III₂ compound [Co^IICo^III₂(μ-L)₂(Ph)₂(μ-Cl)₂]·(CH₃)₂CO·H₂O (1). Our recent study already revealed that the same reaction mixtures in methanol or ethanol produced a heterometallic Sn^IVCo^III (2) or monometallic Co^III complex (3), respectively. Comparison of these organometallic systems shows that the 2,1-intermetallic Ph shift occurs in any of those solvents, but their relevant structural features (mononuclear, dinuclear-heterometallic, and trinuclear mixed valence) are solvent dependent. Geometrical structural rotation is also discussed among the related organometallic Co^IICo^III₂ systems. The AC magnetic susceptibility measurements indicate that 1 is a single molecule magnet (SMM), exhibiting a field-induced slow magnetic relaxation with two modes. The relaxation time for the low-frequency channel is as slow as τ~0.6 s at T = 2.0 K and B_DC = 1.0 T.     

Slow Magnetic Relaxation in a Co2Dy Trimer and a Co2Dy2 Tetramer

The combination of Co(III) and Dy(III) with a compartmental Schiff base ligand (H₃L=3-[(2-Hydroxy-3-methoxy-benzylidene)-amino]-propane-1,2-diol), presenting three different coordinating pockets, has allowed the synthesis of two novel Co(III)−Dy(III) complexes: [Co₂Dy(HL)₄]NO₃ ⋅ 2CH₃CN ( 1 ), a rare example of trinuclear linear Co^III₂Dy^III complex (and the first with slow relaxation of magnetization in absence of a DC field) and [Co₂Dy₂(μ₃−OH)₂(HL)₂(OAc)₆] ⋅ 4.6H₂O ( 2 ), the first tetranuclear Co^III₂Dy^III₂ cluster with a rhomb-like structure where the Co(III) ions are connected along the short diagonal of the rhomb. 1 presents two different relaxation processes: a fast relaxation dominated by Quantum tunnelling (QT) and a slow relaxation with an energy barrier of 40 K. 2 shows two close relaxation processes without applied DC fields that follow QT and Orbach mechanisms whereas for H_DC=500 Oe, the QT is cancelled and a direct term appears. Here we present the synthesis, X-ray structure and magnetic characterization of these two Co(III)−Dy(III) single-ion/molecule magnets.     

Homochiral Dysprosium Phosphonate Nanowires: Morphology Control and Magnetic Dynamics

Controllable synthesis of uniformly distributed nanowires of coordination polymers with inherent physical functions is highly desirable but challenging. In particular, the combination of chirality and magnetism into nanowires has potential applications in multifunctional materials and spintronic devices. Herein, we report four pairs of enantiopure coordination polymers with formulae S-, R-Dy(cyampH)₃ ⋅ CH₃COOH ⋅ 2H₂O ( S -1 , R -1 ), S-, R-Dy(cyampH)₃ ⋅ 3H₂O ( S -2 , R -2 ), S-, R-Dy(cyampH)₂(C₂H₅COO) ⋅ 3H₂O ( S -3 , R -3 ) and S-, R-Dy(cyampH)₃ ⋅ 0.5C₂H₅COOH ⋅ 2H₂O ( S -4 , R -4 ) [cyampH₂=S-, R-(1-cyclohexylethyl)aminomethylphosphonic acids], which were obtained depending on the pH of the reaction mixtures and the specific carboxylic acid used as pH regulator. Interestingly, compounds 3 were obtained as superlong nanowires, showing 1D neutral chain structure which contains both phosphonate and propionate anion ligands. While compounds 1 , 2 and 4 appeared as block-like crystals, superhelices and nanorods, respectively, and exhibited similar neutral chain structures containing only phosphonate ligand. Slow magnetization relaxation characteristic of single-molecule magnet (SMM) behavior was observed for compounds S -1 and S -3 . Theoretical calculations were performed to rationalize the magneto-structural relationships.     

Magnetic field‐induced alignment of polybenzimidazole microstructures to enhance proton conduction

Aligned polymer microstructures in the field of biomaterials, semiconductors, and ion‐conductive membranes expand steadily. Here, an alternative aligned polybenzimidazole (WM PBI) microstructures fabrication strategy based on the utilization of a weak magnetic field (0.3 T) via the solvent casting method is demonstrated. The anisotropic alignment is induced by the interaction of the π‐electron‐rich structure with the magnetic field. A ripple‐like structure was observed in the field‐emission scanning electron microscopy image for the WM PBI membrane, which depicted the successful alignment of the PBI structure toward magnetic field direction. Electrochemical studies revealed the bulk resistance of WM PBI with only 13.71 × 10³ Ω compared to the unaligned PBI (WOM PBI) (63.01 × 10³ Ω). WM PBI marked as the highest proton conductivity of 610.66 × 10^?6 S cm^?1, and it was proven that the external magnetic field does bring the impact toward the augmentation of the proton conductivity, which is useful in various future generation applications.