Analysis of Torque Ripple of Permanent Magnet Brushless DC Motor

Torque tripple has significant effect on performance of permanent magnet brushless DC motor. This paper presents a mathematical model built for such a motor, the analysis of torque tripple for a brushless DC motor with sinusoidal flux distribution, which is verified by torque tripple experiments run with a test motor, and equations developed for torque tripple resulting from different sator current errors.

Temperature Research of Permanent Magnet Brushless DC Motor for Electric Balanced Vehicle

A power system structure composed of a brushless DC motor and a cycloidal reducer for electric balanced vehicle has been proposed, and the temperature of important components in this structure would be discussed. The loss generated by the cycloid reducer is negligible, it’s only need to analyze the thermal field of motor. Since the temperature change will affect the material properties of the target motor, the electromagnetic and temperature fields, involved in the motor, are selected for coupling calculation to determine whether the final temperature distribution can meet the requirements of vehicle for use.

Simplified EKF Based Sensorless Direct Torque Control of Permanent Magnet Brushless AC Drives

A simplified extended Kalman filter (EKF) based sensorless direct torque control technique for a permanent magnet brushless AC drive is proposed. Its performance is compared with that obtained with other sensorless methods for estimating the rotor speed and position from a stator flux-linkage. Since the EKF has an inherently adaptive filtering capability and does not introduce phase delay, the technique provides better speed estimates. In addition, the technique is easy to implement and requires minimal computation.

Study on three dimensional electromagnetic model for permanent magnet linear synchronous motor

In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D electromagnetic field model of PMLSM is established. Special attention is paid to its structure and the influence of longitudinal and transverse end effect. The distribution of electromagnetic field of PMLSM can be obtained directly and promptly by using FFT algorithm. It can also be used for the analysis of other LSM.

Design optimization of a slotless PM brushless motor with helical edge wound laminations for rim driven thrusters

This paper discusses the analysis and design of a very thin slotless permanent magnet （PM） brushless motor whose stator laminations are manufactured from a single strip of steel that is edge wound into a spiral （like a ＂Slinky＂） and then fitted over the windings that are preformed on the outside surface of a non-conducting former. Analytical and finite element analysis （FEA） are used to determine the con- strained optimum dimensions of a motor used to drive a rim driven thruster in which the motor rotor is fit- ted onto the rim of the propeller and the stator is encapsulated in the thin Kort nozzle of the thruster. The paper describes the fabrication of a demonstrator motor and presents experimental results to validate the theoretical calculations. Experimental motor performance results are also reported and compared with those of a slotted motor that fits within the same active radial dimensions as the slotless motor. The slotless motor, which has longer active length and endwindings, and thicker magnets than the slotted motor, was found to be less efficient and more expensive （prototype cost） than the slotted machine.

Six-step Voltage Control of PM Brushless AC Motors under High Speed Flux-weakening Operation for EV/HEV Applications

The torque-speed characteristics of brushless motor having an interior permanent magnet rotor and a sinusoidal back-emf waveform are compared experimentally when it is operated in brushless AC(BLAC) mode and brushless DC (BLDC) modes with both 2-phase,120° conduction(BLDC-120) and 3-phase,180° conduction(BLDC-180).Particular emphasis is on high-speed,six-step voltage controlled,flux-weakening operation.It is shown that for EV/HEV applications,even for interior PM brushless motors which have sinusoidal back-emf waveforms,in order to achieve maximum torque per ampere capability over wide operation speed range,it is advantageous to employ a hybrid operation mode-BLAC operation in the constant torque region and six-step voltage control(BLDC-180 operation,together with current phase control) in the flux-weakening region.

一种轴流式磁悬浮心脏血泵驱动电机优化设计

为提高人工心脏泵的工作性能和稳定性,以一种轴流式磁悬浮人工心脏泵作为研究对象,设计优化了一种适用于心脏泵的永磁无刷直流电机。采用有限元仿真软件验证了该电机的性能符合设计要求,并通过对比分析的方法对其齿槽转矩和起动特性进行了研究。仿真结果表明:该心脏泵驱动电机对比传统驱动电机齿槽转矩减小了约11.7%,并且电机具有良好的起动特性,有效提高了心脏泵的工作性能和稳定性,为轴流式磁悬浮人工心脏泵驱动电机的研制提供一定的指导作用。

Improved Sensorless Operation of Interior PM BLAC Motor Drives with Reduced-Order EKF

It is a challenge to realise an EKF-based sensorless controller for an Interior Permanent Magnet （IPM） brushless ac motor drive due to the influence of nomlinearities and rotor saliency. An improved reduced-order EKF method is presented, reducing the rotor position estimation error of an IPM motor, as evident in [1] due to the neglect of saliency. The effectiveness of the proposed method is verified experimentally.

基于径向气隙磁密和定子电流的永磁同步电机均匀退磁故障诊断研究

该文提出一种基于径向气隙磁密和定子电流的永磁同步电机均匀退磁故障诊断方法。首先,建立电机的d轴等效磁路模型,分析均匀退磁故障后径向气隙磁密的变化规律;然后,获取电机的径向气隙磁密和定子电流信号,对各极下径向气隙磁密幅值进行归一化处理,并绘制雷达图,根据雷达图和比较相同定子电流幅值下健康电机和故障电机的各极下径向气隙磁密幅值的平均值,来诊断均匀退磁故障;利用空载各极下径向气隙磁密幅值的平均值计算故障程度。最后,仿真和实验结果均验证所提均匀退磁故障诊断方法的有效性。

双层复合护套高速永磁电机转子涡流损耗解析模型

在表贴式高速永磁电机中,双层复合护套可以有效抑制转子涡流损耗。目前,针对双层复合护套转子涡流损耗的研究主要采用有限元法,但该方法存在耗时、对薄护套网格剖分较困难等问题,因此该文基于精确子域法提出了一种考虑定子开槽、涡流反作用的双层复合护套高速永磁电机转子涡流损耗通用解析模型。该模型同时考虑了永磁磁场励磁和电枢磁场励磁,可以计算负载磁场作用下的双层复合护套转子涡流损耗。此外,该模型还可进一步拓展至多层复合护套转子涡流损耗计算。通过该解析模型研究了双层复合护套不同护套厚度配比、不同护套材料对转子涡流损耗的影响。最后,将解析计算结果与有限元及C型铁心实验结果进行对比,验证了该解析模型的有效性。

双层永磁体结构高速永磁电机转子涡流损耗解析模型

对于采用低电导率护套高电导率永磁体的表贴式高速永磁电机,在永磁体和保护套之间增加一层低电导率的永磁体,可有效降低永磁体上的涡流损耗。目前,对于双层永磁体转子结构的电机在使用有限元软件进行转子涡流损耗计算时,因为需要寻求两种永磁体不同厚度配比下的最优方案,所以要进行大量参数化,导致计算时间长、效率低。针对这一问题,该文基于精确子域法,建立了一个考虑定子开槽以及涡流反作用影响的双层永磁体结构转子涡流损耗解析模型,可同时对电枢磁场和负载磁场下双层永磁体结构转子涡流损耗进行求解,并且该模型可扩展至多层永磁体复合结构的转子涡流损耗计算。在此基础上分析了双层永磁体结构下外层永磁体不同厚度和不同材料对转子涡流损耗和内层永磁体消耗量的影响。最后通过有限元仿真和C型铁心实验验证了该解析模型的有效性。

车用永磁无刷直流电机弱磁控制仿真研究

永磁无刷直流电动机的转矩与转速会对电机的控制精度造成影响,导致电机弱磁控制效果差。为了提升整体控制性能,提出车用永磁无刷直流电机弱磁控制仿真方法。分析车用永磁无刷直流电机弱磁转矩特性,获取电机电磁转矩关系。根据获取结果建立永磁无刷直流电机弱磁控制系统,利用该系统控制电机弱磁的电磁转矩与运行效率,以此实现整体控制。实验结果表明,通过对所提方法开展电机运行效率测试、电机运行稳定性测试,验证了上述方法的有效性。

基于参数扰动估计的双三相永磁同步电机鲁棒模型预测控制

双三相永磁同步电机因其损耗小、效率高、容错能力强等特点,广泛应用于航空航天技术、电动汽车等领域。为优化双三相永磁同步电机控制性能,采用双d-q坐标变换对双三相永磁同步电机进行数学建模,为减小电流纹波,在传统模型预测电流控制策略基础上,增加延时补偿;考虑电机参数扰动的影响,提出一种能够对参数进行在线估计的滑模观测器,以提高控制系统鲁棒性,最后在MATLAB/Simulink中进行系统抗负载扰动与鲁棒性能仿真分析。仿真结果表明,改进后的控制策略提高了电机的响应速度,超调减小,系统对电机参数扰动的敏感性减弱,系统抗负载能力和鲁棒性增强。

微型永磁无刷直流电机的设计与优化

对一款航空用微型永磁无刷直流电机进行了设计,永磁体选用钐钴进行Halbach阵列充磁,并对电机的部分参数进行了优化,与原方案相比,优化了电机的输出转矩。制作了一款实物样机,通过对样机的测试,验证了优化的可行性。

车用永磁同步电机矢量控制策略研究

为提升混合动力汽车内置式永磁电机磁阻转矩利用效率,以相同的功率输出时能降低电机所需电流,并提高控制系统效率,开发了一种最大转矩电流比(MTPA)控制与弱磁控制相结合的策略。以基速为衡量标准,在基速之下时采用MTPA矢量控制策略,满足低转速工况的高扭矩需求并提升混合动力汽车续航里程;在基速之上时采用弱磁控制策略,基于直流侧电压利用率判断是否采用弱磁控制,并且通过引入反馈解耦,降低耦合项在转速较高时引发的不利影响。仿真与实验结果表明,该控制策略控制精度高、动态响应快,适用于混合动力汽车永磁电机控制系统。

热限制下铁芯饱和对永磁无刷直流电机过载转矩的影响

合理的铁芯饱和点可提升高过载永磁无刷直流电机的转矩,转矩提升优化的热限制条件会对最佳铁芯饱和点产生影响。有必要探究热限制下铁芯饱和程度对转矩的影响规律,为提升转矩提供理论参考。为此构建了一种考虑铁芯饱和及电枢反应的等效磁路模型,基于该磁路模型,推导了转矩、损耗和热限制条件的表达式,建立了转矩与尺寸及热限制条件之间的解析关系,分析了不同热限制条件下铁芯饱和程度对转矩的影响,探讨了同时限制电流密度及铜耗密度条件下最大转矩与铁芯饱和程度的关系,对比了不同材料对转矩提升的效果。研究表明,在热限制下存在一个使转矩最大的磁密点,不同热限制条件将影响最优磁密点的大小。分别使用有限元仿真与实验测试对解析结果进行了验证,与解析值相比,仿真结果和实验结果的误差分别小于2%和小于10%。仿真和实验结果表明,所搭建考虑饱和的电磁模型以及分析计算过程均具有较高准确性。

永磁无刷直流电机定子齿部辅助槽对转矩特性的影响分析

推导了齿槽转矩表达式并分析了电机槽极配合对齿槽转矩和转矩波动的影响。基于一款6槽8极的永磁无刷直流电机,研究定子齿顶开槽对齿槽转矩的抑制作用。有限元仿真分析表明,电机齿槽转矩和转矩特性与辅助槽数量和槽口尺寸有较大关系,当定子齿顶开2个辅助槽、槽深0.6 mm槽宽2.0 mm时,齿槽转矩下降了69.1%。样机实测数据验证了有限元分析的结果。

电动汽车轮毂永磁无刷直流电机控制系统的速度控制

轮毂电机驱动是电动汽车采取的一种新型驱动方式。针对电动汽车轮毂永磁无刷直流电机的多变量、高度非线性以及强耦合的特点,将电机控制系统的转速控制器设计为模糊神经网络PID调节器,通过鸡群算法和改进BP算法分别对模糊神经网络进行优化和训练,实现模糊神经网络PID调节器的最优参数输出。系统仿真和实验分析验证表明,基于模糊神经网络PID转速调节器的电机控制系统具有很强的转速跟踪、抑制超调、抗干扰、鲁棒性等动态性能。

永磁无刷直流电机空载气隙磁场和绕组反电势的解析计算

该文利用许-克变换构造了考虑齿槽效应的气隙相对比磁导函数,该气隙相对比磁导函数反映了齿槽效应对气隙磁场分布的影响,且这种影响的程度随气隙中的径向位置而变化。在忽略铁心饱和的情况下,结合偏微分方程的解析算法,提出了一种考虑齿槽效应的永磁无刷直流电机空载气隙磁场分布和相绕组反电动势的解析计算方法。计算结果与二维有限元计算结果对比,其计算波形和大小吻合很好。证明此方法是正确的、可靠的,为永磁无刷直流电机优化设计和性能分析提供了基本分析手段。

永磁无刷直流电机磁阻转矩的解析计算方法

该文利用许-可变换,构造了考虑齿槽效应的等效气隙磁导函数,结合偏微分方程的解析算法,计算出等效气隙内任意半径上的气隙磁通密度分布,由此提出了一种永磁无刷直流电机磁阻转矩的解析计算方法,其计算结果与有限元计算结果对比,转矩波形基本吻合,证明此方法是正确的、可靠的;同时该方法可应用于磁极分段移位、齿面加辅助凹槽、移动相邻磁极等结构的磁阻转矩的计算,为永磁无刷直流电机设计和优化提供了基本分析手段。