ANALYSIS OF WORKING MODES OF HYBRID EXCITATION DOUBLY SALIENT MOTOR

A more accurate analysis method on working modes is proposed by considering the winding terminal voltage and the eondueting power device as state parameters. For the three-phase hybrid excitation doubly salient machine （HEDSM） motor and its three-phase full-bridge inverter, in the proposed analytical method, all possible working modes are generally listed. Then, with the H_PWM-L_ON control strategy, the working modes are detailed with eorresponding equivalent circuits. Experimental results verify the robustness of the analysis.

Hybrid Excitation Flux Switching Motor with Permanent Magnet Placed at Middle of Field Coil Slots and High Filling Factor Windings

Design and experimental studies on a hybrid excitation flux switching motor as a traction motor for hybrid electric vehicles drive are presented.A stator body of the motor consists of not only laminated silicon-iron electromagnetic steel and three-phase armature windings,but also both of field excitation coils and permanent magnets working together as a variable field magnetomotive force source.On the other hand,a rotor is composed of just laminated silicon-iron electromagnetic steel with salient poles like switched reluctance motor.To bring out the best in drive performances of the hybrid excitation flux switching motor as a variable flux motor for the application,each material adopted for the stator and rotor body should be designed properly in terms of motor efficiency,maximum torque and power densities and so forth.As some of them,in this paper,thinner silicon-iron electromagnetic steel sheet and permanent magnets with high remanent and low amount of Dysprosium used are applied for achieving higher motor efficiency.Moreover,all coils wound flatwise and edgewise using rectangular wires are introduced to realizing high filling factor for reduced copper losses.Experimental tests using a 60kW prototype of the motor demonstrates the designed motor has good motor efficiency under frequent operating points expected for the target vehicle drive.

Cooling System Design and Thermal Analysis of Modular Stator Hybrid Excitation Synchronous Motor

Hybrid excitation synchronous motor has the advantages of uniform and adjustable electromagnetic field, wide speed range and high power density. It has broad application prospects in new energy electric vehicles, wind power generation and other fields. This paper introduces the basic structure of hybrid excitation motor with modular stator, and analyzes the operation principle of hybrid excitation motor. The cooling structure of the water-cooled plate is designed, and the effects of the thickness of the water-cooled plate and the number of water channels in the water-cooled plate on the heat dissipation capacity of the water-cooled plate are analyzed by theoretical and computational fluid dynamics methods. The effects of different water cooling plate structures on water velocity, pressure drop, water pump power consumption and heat dissipation capacity were compared and analyzed. The influence of different inlet flow velocity on the maximum temperature rise of each part of the motor is analyzed, and the temperature of each part of the motor under the optimal water flow is analyzed. The influence of the traditional spiral water jacket cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of the motor components is compared and analyzed. The results show that the water-cooled plate cooling structure is more suitable for the modular stator motor studied in this paper. Based on the water-cooled plate cooling structure, the air-water composite cooling structure is designed, and the effects of the air-water composite cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of each component of the motor are compared and analyzed. The results show that the maximum temperature rise of each component of the motor is reduced under the air-water composite cooling structure.

Corticospinal excitability during motor imagery is diminished by continuous repetition-induced fatigue

Application of continuous repetition of motor imagery can improve the performance of exercise tasks.However,there is a lack of more detailed neurophysiological evidence to support the formulation of clear standards for interventions using motor imagery.Moreover,identification of motor imagery intervention time is necessary because it exhibits possible central fatigue.Therefore,the purpose of this study was to elucidate the development of fatigue during continuous repetition of motor imagery through objective and subjective evaluation.The study involved two experiments.In experiment 1,14 healthy young volunteers were required to imagine grasping and lifting a 1.5-L plastic bottle using the whole hand.Each participant performed the motor imagery task 100 times under each condition with 48 hours interval between two conditions:500 mL or 1500 mL of water in the bottle during the demonstration phase.Mental fatigue and a decrease in pinch power appeared under the 1500-mL condition.There were changes in concentration ability or corticospinal excitability,as assessed by motor evoked potentials,between each set with continuous repetition of motor imagery also under the 1500-mL condition.Therefore,in experiment 2,12 healthy volunteers were required to perform the motor imagery task 200 times under the 1500-mL condition.Both concentration ability and corticospinal excitability decreased.This is the first study to show that continuous repetition of motor imagery can decrease corticospinal excitability in addition to producing mental fatigue.This study was approved by the Institutional Ethics Committee at the Nagasaki University Graduate School of Biomedical and Health Sciences(approval No.18121302)on January 30,2019.

Enhanced motor cortex excitability after spinal cord injury

Transcranial magnetic stimulation（TMS）represents a useful non-invasive approach to studying cortical physiology,in addition to the descending motor pathways（Hallett,2000）,and may also be used to investigate the intracortical facilitatory and inhibitory mechanisms.

Repetitive transcranial magnetic stimulation for lower extremity motor function in patients with stroke:a systematic review and network meta-analysis

Transcranial magnetic stimulation,a type of noninvasive brain stimulation,has become an ancillary therapy for motor function rehabilitation.Most previous studies have focused on the effects of repetitive transcranial magnetic stimulation(rTMS)on motor function in stroke patients.There have been relatively few studies on the effects of different modalities of rTMS on lower extremity motor function and corticospinal excitability in patients with stroke.The MEDLINE,Embase,Cochrane Library,ISI Science Citation Index,Physiotherapy Evidence Database,China National Knowledge Infrastructure Library,and ClinicalTrials.gov databases were searched.Parallel or crossover randomized controlled trials that addressed the effectiveness of rTMS in patients with stroke,published from inception to November 28,2019,were included.Standard pairwise meta-analysis was conducted using R version 3.6.1 with the“meta”package.Bayesian network analysis using the Markov chain Monte Carlo algorithm was conducted to investigate the effectiveness of different rTMS protocol interventions.Network meta-analysis results of 18 randomized controlled trials regarding lower extremity motor function recovery revealed that low-frequency rTMS had better efficacy in promoting lower extremity motor function recovery than sham stimulation.Network meta-analysis results of five randomized controlled trials demonstrated that highfrequency rTMS led to higher amplitudes of motor evoked potentials than low-frequency rTMS or sham stimulation.These findings suggest that rTMS can improve motor function in patients with stroke,and that low-frequency rTMS mainly affects motor function,whereas high-frequency rTMS increases the amplitudes of motor evoked potentials.More highquality randomized controlled trials are needed to validate this conclusion.The work was registered in PROSPERO(registration No.CRD42020147055)on April 28,2020.

Plastic Changes of Synapses and Excitatory Neurotransmitter Receptors in Facial Nucleus Following Facial-facial Anastomosis

The remodeling process of synapses and neurotransmitter receptors of facial nucleus were observed. Models were set up by facial-facial anastomosis in rat. At post-surgery day （PSD） 0,7,21and 60, synaptophysin （p38）, NMDA receptor subunit 2A and AMPA receptor subunit 2 （GluR2） were observed by immunohistochemical method and semi-quantitative RT-PCR, respectively. Mean-while, the synaptic structure of the facial motorneurons was observed under a transmission electron microscope （TEM）. The intensity of p38 immunoreactivity was decreased, reaching the lowest value at PSD day 7, and then increased slightly at PSD 21. Ultrastructurally, the number of synapses in nucleus of the operational side decreased, which was consistent with the change in P38 immunoreactivity. NMDAR2A mRNA was down-regulated significantly in facial nucleus after the operation （P〈0.05）, whereas AMPAR2 mRNA levels remained unchanged （P〉0.05）. The synapses innervation and the expression of NMDAR2A and AMPAR2 mRNA in facial nucleus might be modified to suit for the new motor tasks following facial-facial anastomosis, and influenced facial nerve regeneration and recovery.

电励磁与永磁电机脉冲电源系统充放电对比分析

对基于电励磁和永磁同步电机的飞轮储能系统充放电原理进行了详细介绍,结合PID控制技术为飞轮储能系统设计了充放电控制器,分别通过控制励磁和变流器对两种飞轮储能系统进行充放电,在MATLAB/Simulink中搭建了仿真模型,仿真结果表明了控制策略的有效性,并且对两种脉冲电源充放电方式的优缺点进行了总结比较。

基于联合仿真的电励磁同步电机线性自抗扰控制

针对电励磁同步电机(EESM)在车用电机控制方向的研究,通过Maxwell设计EESM有限元模型,基于Simulink搭建电机控制系统模型。然后,根据凸极EESM的电机特性和电磁转矩分析,在控制系统中采用最大转矩电流比(MTPA)矢量控制方式在Simulink-Maxwell进行EESM控制系统的联合仿真验证。同时,控制系统电流环应用线性自抗扰控制(LADRC),基于电机已知参数在LADRC中设计模型辅助—扩张状态观测器(MA-LESO),以观测和消除系统扰动变量。仿真实验表明,采用MTPA矢量控制的电机在带载时转速波动降低,带载能力增强;在电流环中采用MA-LESO的LADRC控制器能使电机转速在稳态时波动更小,在带载时的抗干扰性能更强,电机运行过程相对稳定;电机负载转矩和定子电流在空载、负载时的波形更稳定,显著提升了电机运行性能。

多相自励磁同步电机零低速域高频电流相位优化策略

多相自励磁同步电机通过在定子侧注入高频谐波电流励磁实现零低速域无刷励磁。然而已有的研究对所注入高频电流的相位尚未充分探讨,限制了在零低速域励磁电流和转矩的进一步提升。针对上述问题,首先基于分数槽集中绕组磁动势原理推导数学公式,分析注入高频电流进行励磁的机制;其次,探讨了高频电流的相位对励磁效果的影响,并提出相位优化策略;最后,采用Maxwell建立了自励磁电机模型,并进行有限元分析对所提策略进行验证。研究结果表明:高频电流相位优化策略在100 r/min时,感应电势增强了17.5%,励磁电流上升了7.5%,转矩增大了6.6%,转矩脉动同比减少71.58%。

电针上肢穴位对运动皮层躯干脑区皮质脊髓兴奋性的影响

目的观察电针上肢穴位对健康受试者初级运动皮层(primary motor cortex,M1)躯干脑区皮质脊髓兴奋性的影响。方法纳入15名健康受试者,采用交叉设计。试验一观察电针上肢穴位对竖脊肌(erector spinae,ES)皮质脊髓兴奋性的影响,受试者随机先后进入3组试验,A组电针合谷穴,B组电针孔最穴,C组假针合谷穴。运用经颅磁刺激,检测干预前后对侧M1第一骨间背侧肌、桡侧腕屈肌及ES的运动诱发电位(motor evoked potentials,MEPs)的波幅和潜伏期,ES的MEPs波幅升高者进入试验二。试验二为抑制背侧前运动皮层(premotor cortex,PMd)后电针上肢穴位对ES的皮质脊髓兴奋性的作用研究,受试者随机先后进入两组试验,D组采用抑制PMd配合电针合谷穴干预,E组采用抑制PMd配合电针孔最穴干预。观察并比较两组对侧M1上肢脑区和躯干脑区MEPs的波幅和潜伏期。结果A组和B组干预后上肢脑区及躯干脑区MEPs总波幅均较同组干预前显著增加(P<0.001,P<0.01)。A组干预后上肢脑区及躯干脑区MEPs总波幅均明显高于C组,B组干预后仅躯干脑区MEPs总波幅明显高于C组,差异均具有统计学意义(P<0.001)。D组干预后上肢脑区最佳刺激点MEPs平均波幅及总波幅较同组干预前均显著增加(P<0.05)。D组和E组干预前后躯干脑区最佳刺激点的MEPs平均波幅及总波幅比较,差异也均无统计学意义(P>0.05)。结论生理状况下,电针合谷、孔最穴均可增强ES的皮质脊髓兴奋性,二者之间无明显差异,PMd可能参与其过程。

并列式双转子混合自励磁电机励磁源参数优化设计和磁场调节特性分析

针对永磁同步电机气隙磁场不可调以及传统电励磁电机的效率低等问题,提出了一种新型并列式双转子混合自励磁电机。首先,该电机利用谐波激励原理,通过调节谐波电压可灵活调整励磁电流,在中高速域更容易实现弱磁扩速。其次,保证功率不变的前提下,先分析两部分各占的比重,再分别对励磁源参数进行优化设计。最后,通过调节励磁电流的大小与方向且利用二维有限元模型对所提电机的性能进行验证。仿真结果证明:所提电机具有较好的调磁能力,在弱磁情况下,反电动势幅值接近于0,可以有效实现转速调节。

真空干泵用永磁-磁阻复合式同步电机设计与分析

针对真空干泵用驱动电机在真空环境中转子散热难的问题,设计了一种混合励磁永磁-磁阻复合式同步电机。该电机转子永磁体励磁结构由钕铁硼与铁氧体两种磁体组成,旨在改变永磁体的排布方式,降低电机的损耗。首先,构建电机转子的拓扑结构,并设计两种方案来研究永磁体的排列方式对电机性能的影响;其次,分析转子参数对电机空载反电动势和电磁转矩的影响,并对电机转子的尺寸进行调整;然后,对比两种方案的损耗大小,选择损耗更低的电机方案;最后,通过有限元计算对目标电机进行了温度场分析,结果表明,所设计方案的电机温度分布合理,因此通过改变永磁体的排布方式能有效提升电机效率,降低电机损耗,确保电机稳定运行。

分数极路比绕组形式对可变速抽蓄电机电磁激振力的影响

可变速抽蓄电机定子分数极路比绕组可以解决机组转速、容量、出口电压不匹配问题,但不同的绕组排布也会导致各支路的磁动势不对称,从而影响电机的电磁激振力。为了研究分数极路比绕组形式对可变速抽蓄电机电磁激振力的影响,推导了适用于不同分数极路比绕组形式的可变速抽蓄电机定子磁动势和电磁激振力的解析计算公式,以336 MW的可变速抽蓄电机为例,综合考虑磁动势不对称度、磁动势幅值、相位偏差和短距系数,获得不同分数极路比绕组形式对磁动势和电磁激振力的影响规律,进而建立了基于有限元的可变速抽蓄电机电磁激振力模型,计算了不同分数极路比绕组形式下可变速抽蓄电机电磁激振力,并进一步研究了支路环流对电磁激振力的影响。结果表明,合理的分数极路比绕组排布能有效削弱电磁激振力,且采用节距为14-15-16的不等节距分数极路比绕组方案能最小化环流的影响。研究结果可为可变速抽蓄电机的国产化研制提供技术支持。

基于离线单相周期方波脉冲的三相异步电机启动转矩测试

为了克服三相异步电机启动转矩无载测试现有方法存在的测试精度较低、电网冲击等问题,提出一种基于离线单相方波脉冲的电机启动转矩测试方法。以Y160M-4型三相异步电机为研究对象,给出用于测试启动转矩的单相方波逆变电源结构、工作原理及关键参数计算方法,并利用二维瞬态电磁场数值计算方法,以研究不同激励模式下的启动转矩为目的,获取电机启动过程的电枢电流。结合电机数学模型和坐标变换理论,研究并给出单相正弦波激励下的电机等效电路模型和启动转矩理论计算模型。在此基础上,进一步给出单相方波激励下的启动转矩数据处理方法。经验证,依据所提出的单相方波激励下的电机启动转矩计算方法并结合二维瞬态电磁场数值仿真,启动转矩测试相对误差约为0.25%。研究结果表明,利用该方法计算三相异步电机的启动转矩,测试精度获得明显提高,从而证明了所提方法的正确性和可行性。

一种惯性式路基激振装置的研发与现场标定

基于双轴惯性式振动电机,研制了一套模拟列车荷载作用的路基激振装置ISV400。考虑轨道及路基结构层自重荷载,利用偏心片数量N_(c)、配重块数量N_(a)与供电频率f_(in),调控简谐动载的峰-谷值差值应力σ_(d)、谷值应力σ_(v)和激振频率f_(out),开展ISV400系统现场标定试验,分析f_(out)与f_(in)关系,探究N_(c)、N_(a)组合下σ_(d)、σ_(v)随f_(out)变化规律,明确ISV400稳定工作频率区间,建立激振力估算方程,提出面向路基结构现场动测的设备参数配置方法。研究表明:f_(out)约为f_(in)的0.5倍,f_(out)低于5 Hz时电机转轴欠同步,将导致装置运行不稳定;σ_(d)、σ_(v)测试值分别高于、低于偏心质量旋转离心原理得到的理论值,且两者偏差与f_(out)正相关,f_(out)为15~25 Hz时易受共振影响;f_(out)为5~15 Hz且保持N_(a)恒定时,σ_(d)-f_(out)曲线族不受N_(c)影响,σ_(d)上限约为400 kPa,N_(c)对应的σ_(v)-f_(out)曲线族相互平行。

电励磁磁通切换直线磁悬浮电动机的电磁力分析

以用于轨道交通牵引系统的电励磁磁通切换直线磁悬浮同步电动机(EEFSLMSM)为研究对象。首先分析了EEFSLMSM的结构,并对该电机的运行原理及其电磁推力与悬浮力产生的原理进行了研究。其次,建立了EEFSLMSM的数学模型,推导了该电机的电压、磁链方程以及电磁推力、悬浮力的数学表达式。然后,通过Ansys Maxwell分析了EEFSLMSM的磁场分布和空载反电动势波形,并对电机的调磁能力进行了研究。最后,通过Ansys有限元计算分析,得出了电磁推力、悬浮力和电枢电流以及励磁电流之间的关系。研究结果验证了EEFSLMSM运行的可行性,为牵引及悬浮一体化的设计提供了理论参考。

混合励磁磁悬浮开关磁阻电机转矩建模与分析

针对传统磁悬浮开关磁阻电机的输出转矩小及转矩与悬浮的耦合问题,提出一种四相16/14/8极混合励磁双定子磁悬浮开关磁阻电机。介绍了该电机的拓扑结构、转矩原理与悬浮原理,并优化了转矩绕组的励磁方式,运用有限元法比较分析了该电机与同参数不加永磁体电机的电磁特性,包括电机的转矩特性以及解耦特性,仿真结果验证了该电机自解耦结构的合理性及能有效提高输出转矩。在麦克斯韦应力法基础上,根据电机工作时的磁通分布建立了等效磁路图,采用分段函数拟合铁芯磁化曲线,推导出了考虑磁饱和的转矩数学模型,有限元仿真分析验证了转矩模型与仿真结果较吻合,最小相差约1.4%,最大相差约26%。

振动激励环境下的滚动轴承动载荷测试

载荷是决定轴承使用寿命的关键参数,针对工程应用中轴承实际载荷通常较难获取的问题,基于轴承载荷与接触点位移间的线性关系设计了一种轴承动载荷测试装置。通过静载荷标定得到不同轴承载荷下的力传感器示值,0.99的相关系数表明轴承载荷与力传感器示值呈高度线性相关,采用一元线性回归方法进行拟合,得到轴承载荷与力传感器示值的转化系数,进而通过轴承动载荷测试装置有效测试了振动激励环境下的轴承动载荷。

电推进飞机定子励磁型无刷电机应用研究

基于电推进飞机的发展需求,结合航空背景,研究一种定子励磁型无刷电机应用于飞机电驱动系统的性能指标。分析了该电机的拓扑结构特点,采用参数化建模方法,在ANSYS Maxwell中建立了电机的仿真模型。运用有限元分析,以转矩特性为主要参数,对该电机进行了仿真优化,得到了适合于电推进飞机场合的电机最优模型。对优化后的电机电磁特性进一步分析,包括转矩特性、电机效率、输出功率和磁场分布等。结果表明:优化后的电机永磁体用量减少了0.18 dm^(3),输出转矩提高了7.7%,转矩脉动系数下降了8.1%,输出功率密度达4.8 kW/kg,效率达96.1%。该电机具有结构简单、功率密度高、电机效率高的优点。