Torque Improvement of Spoke-type Permanent Magnet Motor with Auxiliary Stator Using Harmonic Current Control Strategy

The spoke-type permanent magnet motor with auxiliary stator exhibits high torque performance owing to the flux focus effects.To further improve its torque density,this paper proposes a control method by using harmonic current strategy.Based on the theoretical analysis,a 3-D torque look-up table by dq-axis current and electrical angle is established with the aid of the finite element method(FEM).The maximum torque per ampere curve at each rotor position is identified and summarized to adequately indicate the relationship between torque and current amplitude of the motor.Through theoretical derivation,it is concluded that the minimum torque cost curve is the contour line of?Te/?i2,which can be employed to identify the harmonic current for torque density improvement.Compared to traditional strategies,the proposed control strategy can increase torque density of forward and reverse torque by 1.22%and 1.40%,respectively.The experimental results verify the analysis and simulation results,as well as prove the effectiveness of the proposed strategy.

A Novel Pulse Density Modulation with Semi-bridgeless Active Rectifier in Inductive Power Transfer System for Rail Vehicle

In this paper,a novel pulse density modulation(PDM)with semi-bridgeless active rectifier(S-BAR)in inductive power transfer(IPT)system for rail vehicle is proposed.It is to reduce switching losses of the active rectifier in pickups.In the control method,the insulated-gate bipolar transistors(IGBTs)in the S-BAR are controlled by synchronous PDM signals,so that zero-voltage switching(ZVS)and zero-current switching(ZCS)can be achieved in the whole output power range.The output power is regulated by changing the pulse density(PD)of the S-BAR since the it is almost linear proportional with the PD in high quality factor of pickup side.The communication device between the primary side and pickup side is not necessary anymore.The detailed theoretical analyses of the PDM method are provided,and its advantages are shown in a 7.5kW IPT prototype for rail vehicle.The experimental results are presented to verify the analysis and demonstrate the performance.The overall efficiency of the system by PDM control is 74.2%which is improved by 4%compared with phase shift(PS)control at light load.

Effect of power parameter and induction coil on magnetic field in cold crucible during continuous melting and directional solidification

Bottomless electromagnetic cold crucible is a new apparatus for continuous melting and directional solidification;however,improving its power efficiency and optimizing the configuration are important for experiment and production.In this study,a 3-D finite element (FE) method based on experimental verification was applied to calculate the magnetic flux density (Bz).The effects of the power parameters and the induction coil on the magnetic field distribution in the cold crucible were investigated.The results show that higher current intensity and lower frequency are beneficial to the increase of Bz at both the segment midpoint and the slit location.The induction coil with racetrack section can induce greater Bz,and a larger gap between the induction coil and the shield ring increases Bz.The mechanism for this effect is also discussed.

航空电推进电机多层波浪形拓扑及散热设计方法

针对航空电推进电机的散热问题,提出一种基于多层波浪形散热拓扑的航空电推进电机高效散热设计方法。航空电推进电机采用多层波浪形散热拓扑,建立电机等效热网络模型,确定等效热阻、对流换热系数等重要参数,完成电机温度精确计算,并通过CFD仿真验证所建立电机等效热网络模型的准确性和有效性。以此为基础,对比分析传统散热翅和多层波浪形散热拓扑对电机功率密度的影响。基于多层波浪形散热拓扑的等效热网络模型,采用遗传学习粒子群优化(GL-PSO)算法,完成航空电推进电机高效散热优化设计。优化结果表明:相比于原始方案,优化方案的机壳质量减轻15.1%,整个电机的功率密度提升0.06 kW/kg。

无缝内衣机调密机构动力学特性研究

针对现有无缝内衣机中密度电动机输出力矩不稳定、测量困难等问题,研究无缝内衣机调密机构动力学特性。结合无缝内衣机成圈及密度调节工艺,建立调密机构三维模型,得到三角滑块推力与电动机转矩间数学关系,运用SolidWorks Motion模块对调密机构进行动力学仿真。搭建调密机构力学测试平台,将测试推力值代入推力与电动机转矩间数学关系计算。结果表明:测试结果与仿真数据相差3.81%,证明理论及建模仿真正确性,给现有无缝内衣机密度调节控制方案中电动机输出力矩控制提供参考。

新型沙漏形隔磁结构的主副齿式永磁游标电机的设计与分析

基于传统交替极双定子分裂齿式永磁游标电机的拓扑结构提出一种新型沙漏形隔磁结构的主副齿式永磁游标电机,旨在进一步提高电机转矩密度和解决永磁体极间漏磁的问题。依据磁场调制原理,首先对定子主齿和副齿的结构参数进行优化设计,主齿的调节作用使低速旋转永磁体磁场和高速旋转电枢磁场进行耦合,副齿对气隙磁场进一步调节产生其他次有效谐波增加电机的同步转矩分量。在永磁体两侧引入沙漏形隔磁结构,该结构不仅抑制极间泄漏,而且大大降低永磁体径向应力和径向形变;并探究永磁体极弧系数对转矩及功率因数的影响,确定优化设计后的模型参数。最后用有限元仿真结果验证了沙漏形隔磁结构的主副齿式永磁游标电机的优越性,相较于传统的分裂齿式永磁游标电机,该电机具有更大的转矩和更小的转矩脉动。

聚磁式交替极永磁游标电机分析与设计

为了在减少传统聚磁永磁游标电机永磁体用量时,仍能保持较大的转矩密度,提出一种新型聚磁式交替极永磁游标电机。与传统聚磁式永磁游标电机相比,新型拓扑结构电机通过交替极转子设计在减少永磁体用量时仍能保持较好的转矩输出特性。该文首先介绍了聚磁式交替极游标永磁电机的结构特点及工作原理。其次,以输出转矩最大为目标,利用有限元法对所提新结构电机关键参数进行优化分析。最后对比分析了新型聚磁式交替极永磁游标电机与传统聚磁式永磁游标电机的电磁性能,包括气隙磁密、反电势及转矩性能,结果表明在相同的体积下,所提新拓扑电机具有更高的转矩密度及更少的永磁体用量。因此,它在低速大转矩直驱应用场合具有广阔的应用前景。

双调制式轴向永磁齿轮电动机气隙磁场与转矩计算

针对轴向永磁齿轮电动机(Axial Magnetic Gear Motor,AMGM)整体尺寸偏大导致的转矩密度偏低(≤70 kN·m/m^(3))等缺陷,提出了一种双调制式轴向永磁齿轮电动机(Dual-modulation Axial Magnetic Gear Motor,DAMGM)。采用高速侧及低速侧两个调磁环对DAMGM低速转子进行调制,且两个调磁环中的非导磁部分均为永磁体,有效提高了低速转子的输出转矩;另外,与现有AMGM相比,将驱动电动机置于DAMGM高速永磁转子内部,减小了整体轴向尺寸,大幅提高了低速转子的转矩密度(150 kN·m/m^(3))。针对现有3D有限元计算时间长、计算机资源浪费严重等问题,给出一种基于圆柱坐标系的DAMGM三维分析方法。根据调磁环的3种边界条件,建立了调制后DAMGM气隙磁场及电磁转矩的数理模型,不仅计算结果准确(与3D有限元相比,平均计算误差≤5%),而且计算时间短(仅为3D有限元的1/10),便于DAMGM不同参数结构的分析、比较与优化。

聚磁式永磁轮毂电机多目标优化设计

集成二级行星减速器轮毂驱动系统对电机电磁和力学性能提出了更苛刻需求。为进一步提升永磁轮毂电机转矩密度和弱磁范围,提出一种聚磁式永磁轮毂电机拓扑结构,分析转子关键参数对转矩密度、弱磁能力和转子强度的影响规律,确定电机初始优化目标;进一步利用有限元及响应面法构建输出转矩、特征电流及转子应力的代理优化模型,并利用改进布谷鸟算法进行多目标优化设计;对比分析优化前后电机电磁和机械性能。最后,试制75 kW聚磁式永磁轮毂电机,试验结果验证所提多目标优化算法的可行性和有效性。

高温高功率密度永磁伺服电机电磁热耦合设计

介绍了一种适应高温、高功率密度永磁伺服电机热设计方法。通过国内外技术发展现状分析,结合高温环境应用,分析永磁交流伺服驱动电机在适应高温、高功率密度方面的电磁、热设计技术难点,通过提升永磁交流伺服电机电磁、热联合设计方法,提升高功率密度永磁伺服电机的高温适应性。

一种高功率密度伺服电机在重载工业机器人中的应用

研究了一种重载工业机器人用高速高功率密度伺服电机,通过短铁心设计实现了额定速度提高近一倍、功率密度提高14%,通过铁心低磁导梯度设计实现了更高的电感线性度,满足了重载机器人伺服电机的高速高电流可控性的要求。定子拼块和环氧灌封等工艺有效控制了损耗和散热,确保电机可以在高温条件下长期可靠运行。

Dynamic neighborhood genetic learning particle swarm optimization for high-power-density electric propulsion motor

To maximize the power density of the electric propulsion motor in aerospace application,this paper proposes a novel Dynamic Neighborhood Genetic Learning Particle Swarm Optimization(DNGL-PSO)for the motor design,which can deal with the insufficient population diversity and non-global optimal solution issues.The DNGL-PSO framework is composed of the dynamic neighborhood module and the particle update module.To improve the population diversity,the dynamic neighborhood strategy is first proposed,which combines the local neighborhood exemplar generation mechanism and the shuffling mechanism.The local neighborhood exemplar generation mechanism enlarges the search range of the algorithm in the solution space,thus obtaining highquality exemplars.Meanwhile,when the global optimal solution cannot update its fitness value,the shuffling mechanism module is triggered to dynamically change the local neighborhood members.The roulette wheel selection operator is introduced into the shuffling mechanism to ensure that particles with larger fitness value are selected with a higher probability and remain in the local neighborhood.Then,the global learning based particle update approach is proposed,which can achieve a good balance between the expansion of the search range in the early stage and the acceleration of local convergence in the later stage.Finally,the optimization design of the electric propulsion motor is conducted to verify the effectiveness of the proposed DNGL-PSO.The simulation results show that the proposed DNGL-PSO has excellent adaptability,optimization efficiency and global optimization capability,while the optimized electric propulsion motor has a high power density of 5.207 kW/kg with the efficiency of 96.12%.

Numerical simulation of the flow field of a flat torque converter

A flexible flat torque converter was proposed to fulfill the requirement of miniaturization and power density maximization for automobiles.Constructed by two arcs joined by lines,the torus was designed directly from design path.The influence of flatness on the performance of the torque converter was evaluated.The software CFX and standard k-ε model were adopted to simulate the internal flow fields of the torque converter under different flatness ratios.The results indicated that the performance of the torque converter got worse as the flatness declined,but the capacity of pump increased.The efficiency and the torque ratio dropped slightly as the flatness ratio decreased.So the torque converter could be squashed appropriately to get high power density without too much efficiency sacrifice.But when the flatness ratio was below 0.2,there was a significant drop in the efficiency.

表贴式轴向磁通电机梯形削极分段结构研究

采用多极少槽结构和分数槽集中绕组可有效提高轴向磁通永磁(AFPM)电机的转矩密度,但磁动势谐波含量较大、频率较高,会引起永磁体涡流损耗增大和温度升高。通过优化表贴式轴向磁通永磁电机的永磁体结构可有效降低永磁体涡流损耗并抑制转矩波动,因此提出梯形削极分段结构。首先,基于精确子域法分别建立不同永磁体结构的解析模型。其次,通过解析模型和三维有限元模型对不同永磁体结构的气隙磁密、输出转矩和涡流损耗进行分析对比。然后,通过研究永磁体分段对永磁体涡流损耗的影响,确定梯形削极分段结构的参数。最后,制造一台样机并进行实验,实验结果证明,梯形削极分段结构可有效降低永磁体涡流损耗并且改善轴向磁通永磁电机输出性能。

高速高功率密度无轴承永磁薄片电机设计与优化

传统无轴承电机在高速和高功率密度之间难以取得平衡,为此围绕高速高功率密度无轴承永磁薄片电机,对其拓扑结构、绕组形式、主要尺寸等方面进行优化设计,在保证转速和功率密度的基础上有效地提升悬浮性能。通过对运行工况的分析,得出电机拓扑结构需具备的基本特点,提出一种采用环形集成绕组的表贴式无轴承永磁薄片电机。在兼顾转矩和悬浮力输出性能、机械防护可靠性的基础上,对电机的电磁气隙长度和永磁体参数等主要尺寸进行优化设计。针对电机饱和、绕组端部伸出等不利因素,分别采取了超前角弱磁、定子略长的性能提升策略,有效地避免了悬浮力的大幅度跌落。搭建20 000 r/min的无轴承永磁薄片电机有限元仿真模型并制造实物样机。通过对电磁转矩和主、被动悬浮力的分析,证明了本文设计的无轴承永磁薄片电机兼具良好的转矩与悬浮力输出性能,单位幅值电流产生的电磁转矩、主动悬浮力分别为0.166 N·m、4.4 N,电机输出功率10 kW、功率密度5.2 kW/kg。

Mathematical modeling and analysis of gas torque in twin-rotor piston engine

The gas torque in a twin-rotor piston engine(TRPE) was modeled using adiabatic approximation with instantaneous combustion. The first prototype of TRPE was manufactured. This prototype is intended for high power density engines and can produce 36 power strokes per shaft revolution. Compared with the conventional engines, the vector sum of combustion gas forces acting on each rotor piston in TRPE is a pure torque, and the combustion gas rotates the rotors while compresses the gas in the compression chamber at the same time. Mathematical modeling of gas force transmission was built. Expression for gas torque on each rotor was derived. Different variation patterns of the volume change of working chamber were introduced. The analytical and numerical results is presented to demonstrate the main characteristics of gas torque. The results show that the value of gas torque in TRPE falls to be less than zero before the combustion phase is finished; the time for one stroke is 30° in terms of the rotating angle of the output shaft; gas torque in one complete revolution of the output shaft has a period which is equal to 60° and it is necessary to put off the moment when gas torque becomes zero in order to export the maximum energy.

微型高功率密度无刷电动机设计分析

针对微型高功率密度无刷电机,从极槽配合选择、提高仿真计算结果准确性方面对其进行分析,并设计一款产品进行加工生产及试验,验证了设计方法是合理有效的。

涵道风扇电机强迫风冷散热结构设计与实验

针对涵道风扇电机的轻量化高效散热需求,提出基于涵道风扇内部流场的强迫风冷散热方法,设计了肋片高度为3 mm、6 mm、9 mm和12 mm的四种风冷散热结构,应用工程估算和CFD方法对不同风速下散热效果进行对比分析,搭建实验平台开展地面试验验证。结果表明,在桨毂上增加散热肋片能够有效提高散热效率,壁面温升可降低至无肋片模型的74%、55%、44%、35%;对于轴向风冷,肋片能显著强化散热,但是存在温度不均的问题。工程估算和CFD方法对电机的带肋表面风冷散热分析有较好的精度,可用于涵道风扇电机的温升预示,为涵道风扇推进系统的使用提供依据。根据分析结果提出了高功率密度电机强化散热的研究方向。

空轨车辆用永磁同步牵引电动机研制

空轨车辆运行于空中轨道,其永磁同步牵引电动机存在结构紧凑、转矩密度高、损耗密度大等问题,同时还需要具体低齿槽转矩及低转矩脉动等。通过对电磁设计、热管理设计、结构设计等关键技术进行研究,开发了样机,先后通过了单电机试验、地面联调试验和装车运行考核。试验结果分析表明,该电机满足空轨车辆指标要求,验证了设计的可行性。

新能源商用车高转矩密度永磁同步电机设计

采用有限元分析方法,设计了一款额定功率60kW的新能源商用车永磁同步电机。利用参数化分析方法,研究了定子槽深和隔磁桥厚度等关键尺寸对电机转矩密度的影响。对V字型转子磁钢的夹角进行了参数化寻优,以抑制磁场谐波含量并减小电机的转矩波动。样机主要性能参数的试验结果表明,该电机的有效转矩密度达到21.5N·m/kg,最高效率96.1%,且效率大于85%的高效运行区域占比达到89.6%。文章所述有限元参数化分析方法和电机关键结构参数优化方法,对提高电机转矩密度和扩大高效运行区间具有良好的效果。