A Novel Open-winding Permanent Magnetic Starter-generator

针对永磁电机应用于车载起动／发电系统时存在的电压调节困难、适用转速范围窄、功率因数较低等问题，提出一种新型永磁车载起动／发电系统。通过引入绕组开路型永磁电机，绕组一端接整流桥形成输出直流侧，另一端接逆变桥形成控制端，构成具有宽转速范围和高效率的永磁电机起动／发电系统。分析该系统的起动、发电一体化工作原理，给出了通过逆变侧变换器实现发电机电压、电流控制的方案。仿真和实验结果表明，该新型车载起动／发电系统具有优良的发电调压控制性能，并且适应较宽的转速范围。

Performance analysis of 20 Pole 1.5 KW Three Phase Permanent Magnet Synchronous Generator for low Speed Vertical Axis Wind Turbine

This paper gives performance analysis of a three phase Permanent Magnet Synchronous Generator (PMSG) connected to a Vertical Axis Wind Turbine (VAWT). Low speed wind condition (less than 5 m/s) is taken in consideration and the entire simulation is carried in Matlab/Simulink environment. The rated power for the generator is fixed at 1.5 KW and number of pole at 20. It is observed under low wind speed of6 m/s, a turbine having approximately1 mof radius and2.6 mof height develops 150 Nm mechanical torque that can generate power up to 1.5 KW. The generator is designed using modeling tool and is fabricated. The fabricated generator is tested in the laboratory with the simulation result for the error analysis. The range of error is about 5%-27% for the same output power value. The limitations and possible causes for error are presented and discussed.

Rotor Strength Analysis of High-speed Permanent Magnet Synchronous Motors

为了对转子进行有效的冷却，在满足电机电磁性能的前提下，可通过减小保护套的厚度来尽可能增大定转子之间的气隙，因而必须对保护套和永磁体进行强度校核。将转子受力状况简化为平面应变问题，在此基础上推导出了两层过盈配合、三层过盈配合转子的应力场、应变场、位移场的解析公式，并利用有限元方法验证了解析公式的正确性。归纳了高速情况下热套式永磁转子强度设计准则，为转子的优化设计提供了理论依据。以一台额定转速120kr／min、10kW的高速永磁同步电机为例，给出了两种常用过盈配合高速电机转子的强度设计方法。

Analysis for Rotor Losses of High Speed Permanent Magnet Synchronous Motor

This paper presents an analysis based on analytical method for solid rotor motors for determining the rotor eddy current losses due to the current harmonics of the stator winding. The accuracy of the analytical results is verified by experiments.

Novel Rotors with Low Eddy Current Loss for High Speed Permanent Magnet Machines

Due to the large rotor eddy current loss and low thermal conductivity of carbon fiber sleeve,the high temperature usually occurs in high speed permanent magnet machines(HSPMMs)at the rated operation condition,resulting in irreversible demagnetization of the permanent magnet(PM).To obtain low rotor temperature,two novel rotor structures with low rotor eddy current loss are proposed in this paper.With the output torque and air gap flux density unchanged,the performance of HSPMMs with the two proposed rotor structures are analyzed based on finite element algorithm(FEA),including eddy current loss and temperature.Finally,the appropriate parameters of the proposed rotor structures are selected,and the electromagnetic(EM)performance,rotor stress and temperature are compared with those of the conventional rotor structure.Index Terms-Eddy current loss,finite element algorithm(FEA),electromagnetic(EM)performance,high speed permanent magnet machines(HSPMMs).

Investigation of Optimal Split Ratio of 6-Slot/2-pole High Speed Permanent Magnet Motor with Toroidal Winding

Split ratio,i.e.the ratio of stator inner diameter to outer diameter,has a closed relationship with electromagnetic performance of permanent magnet(PM)motors.In this paper,the toroidal windings with short end-winding axial length are employed in the 6-slot/2-pole(6s/2p)PM motor for high speed applications.The split ratio is optimized together with the ratio of inner slot to outer slot area,i.e.slot ratio,considering stator total loss(stator iron loss and copper loss).In addition,the influence of maximum stator iron flux density and tooth-tip on the optimal split ratio,slot ratio,and average torque is investigated.The analytical predictions show that when the slot ratio is 0.5,the maximum torque can be achieved,and the optimal split ratio increases with the decrease of slot ratio,as confirmed by the finite element(FE)analyses.Finally,some of predicted results are verified by the measured results of 6s/2p prototype motor with 0.5 slot ratio.

Thermal analysis of high speed permanent magnetic generator

High-speed permanent magnetic generators (HSPMG) are common and important power generation equipments used in distributed generation systems. A 100 kW level HSPMG is investigated in this paper, and it is fluid-thermal coupling analyzed. The transient 2D electromagnetic field while machine is under rated operating is analyzed by using the time-stepping FEM, from which the electromagnetic performances and the loss distributions are obtained. Then, an analysis model for fluid-solid temperature field analysis is established. Taking losses as the distributed heat sources, the 3D thermal field is coupling calculated. The variations of heat transfer coefficient and temperature of fluid in stator grooves along the axial direction, as well as the whole region 3D temperature distribution in HSPMG are obtained. Then, considering the variations of heat sources distributions and heat transfer conditions, 3D temperature fields of HSPMG operating under different speeds are calculated, and the influences of machine operating speed on the HSPMG thermal performance are studied, based on which, the functions of machine temperature with operating speed and stator windings resistance are proposed. The obtained conclusions may provide a useful reference for the design and research of HSPMG.

Comparative Performance of Fixed-Speed and Variable-Speed Wind Turbine Generator Systems

In the early development of the wind energy, the majority of the wind turbines have been operated at constant speed. Subsequently, the number of variable-speed wind turbines installed in wind farms has increased. In this paper, a comparative performance of fixed and variable speed wind generators with Pitch angle control has been presented. The first is based on a squirrel cage Induction Generator （IG） of 315 kW rated power, connected directly to the grid. The second incorporated a Permanent Magnet Synchronous Generator （PMSG） of 750 kW rated power. The performances of each studied wind generator are evaluated by simulation works and variable speed operation is highlighted as preferred mode of operation.

Wide Speed Range Permanent Magnet Synchronous Generator Design for a DC Power System

A wide speed range permanent magnet synchronous generator(PMSG)system is studied in this paper,including the PMSG design and comparative study on control strategies with a pulse width modulation(PWM)rectifier,the purpose of which is to regulate the DC-link voltage.It is of great importance to study the foregoing DC power system based on the PMSG and PWM rectifier,where vector control(VC)can be implemented and the corresponding field-weakening strategy can be realized by injecting a field-weakening current component without any auxiliary devices.Large machine inductance is desired in order to limit the short-circuit current and the loaded voltage drop.Different control strategies including VC,direct torque control(DTC)and direct voltage control(DVC)are studied and compared with both simulations and experiments.

Overview and Analysis of PM Starter/Generator for Aircraft Electrical Power Systems

More Electrical Aircraft(MEA)which replaces the hydraulic and pneumatic power by electrical power leads to reducing emissions and fuel consumption.The MEA concept has led to a growing use of the starter/generator(S/G)system.Permanent magnet(PM)machines have been gaining interests for aircraft S/G system application over the last few years.This is mainly due to the several advantages,including high power density,high efficiency and high speed ability.The shortcoming of the PM machines is the de-­excitation problem in case of a failure,which is a main issue for the aircraft application.However,by using a PM machine with high reactance or multiphase configuration,the fault-­tolerant ability can be improved.In terms of the aircraft S/G system,this paper is going to present a comprehensive analysis of PM machines.Firstly,the state-­of-­the-­art of PM starter/generator(PMS/G)is summarized and the basic structure of PMS/G system is analyzed.Next,key technologies of the PMS/G system are summarized and analyzed.Finally,a flux weakening fault protection strategy that is used to suppress the turn-­to-­turn short circuit(SC)current is studied,simulated and verified.With the breakthrough of key technologies based on the development of high temperature electromagnetic material and high temperature power electronics,the PMS/G will be a potential candidate for aircraft S/G system including the embedded power generation system.

1.1 MW高速内置式永磁同步电机新型转子拓扑设计与强度优化

大功率高速永磁电机中通常采用绑扎碳纤维护套的方式来降低转子应力,然而护套厚度过大会导致等效气隙增加,电机性能随之降低。针对这一问题,设计了一种具有新型转子拓扑结构的1.1 MW、18 000 r/min的内置式高速永磁同步电机。该结构采用永磁体分段设计,并增设加强筋,分担转子隔磁桥处的应力,使护套厚度得到有效降低。同时,将转子外部隔磁桥处替换为非导磁填充块,阻断漏磁路径,提升永磁体利用率。最后,有限元分析结果表明,相较于初始模型,新型结构电机在等效气隙增大1.5 mm的情况下,输出转矩达到600.44 N·m,增加了16.86 N·m,并且新型转子铁心最大应力降低了496.82 MPa,转子结构的机械强度得到显著提高,可为大功率高速永磁电机转子拓扑设计提供参考。

以谐波为导向的轮辐式磁场调制永磁轮毂电机转速波动抑制研究

结合车辆轮毂直驱应用场合需求,以“低速大转矩”能力出色的轮辐式磁场调制永磁轮毂电机为研究对象,系统性开展以谐波为导向的电机转速波动抑制研究。分析齿槽转矩这一引起电机转矩波动的重要因素,确定与之相关联的主导谐波阶次。并且,将关联谐波作为优化设计目标,有效削弱齿槽转矩,从而有助于在电机设计层面实现电机转速波动的抑制。此外,面临轮毂直驱场合复杂工况及恶劣路况的驱动需求,在电机控制层引入“扰动抑制能力出色”的自抗扰控制技术,在自抗扰控制器误差反馈控制律中针对性引入电机齿槽转矩主导谐波的抑制环节,提出谐波导向型线性状态误差反馈控制律,进一步抑制了电机的转速波动。理论分析与实验结果验证了研究的合理性。

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。

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。

低温高速永磁电机硅钢片铁心电磁性能变化机理研究

由于低温泵用高速电机工作在低温环境中,探究低温环境对构件材料性能的影响、低温条件对电机特性的作用机理以及形成统一的选材原则已经成为该类电机亟待解决的问题。采用实验法在常温(25℃)和低温(-196℃)条件下对不同系列的冷轧无取向硅钢片的电磁性能进行了研究,分析了低温环境与频率对硅钢片电磁性能的影响情况。基于实测数据并采用有限元法计算了电机定子铁耗,得到了电机采用不同系列硅钢片的定子铁耗分布以及变化情况。为了探究低温环境下采用不同系列硅钢片时电机定子铁耗变化幅度不同的原因,采用低温冲击法对硅钢片的矫顽力进行测量,验证了有限元计算所得规律的正确性。探明低温条件对硅钢片电磁性能的影响机理,提出低温高速高频电机铁心材料的选材建议,为低温工作环境下低温电机铁心材料选材提供理论借鉴与参考。

基于广义二阶积分器的高频脉振电压注入PMSM无位置传感器控制

传统高频脉振电压注入法需要使用多个滤波器滤除杂波信号,会使系统产生延时且估计误差较大,本文提出广义二阶积分器代替滤波器滤除杂波,实现对转速和转子位置估计精度的提高。针对传统高频脉振电压注入法位置观测精度和动态性能较差的问题,采用一种基于广义二阶积分器的速度环和电流环位置误差信息提取方法。采用广义二阶积分器代替位置观测闭环的带通滤波器和低通滤波器,提取电机速度和转子位置信息,简化参数整定过程,提高位置观测精度;同时用2个广义二阶积分器串联取代电流环中的低通滤波器,提取基频电流分量,增加电流环带宽,减小系统延时。仿真和实验结果表明,该方法提高了位置观测精度和系统的动态响应性能。

基于滑模观测器的高速PMSM无传感器控制

针对基于饱和函数滑模观测器方法存在调节参数多及低通滤波器带来的相位延迟问题,研究一种基于超螺旋算法的滑模观测器无传感器控制策略,通过理论推导及系统稳定性分析,设计了一种滑模系数根据转速变化在线调节的自适应滑模系数算法。通过实验验证了该方法相比于基于饱和函数滑模观测器,能在较宽速度范围内有效地抑制抖振,提高了无传感器控制系统的估计精度,简化了参数调节过程及滤波器设计环节。

兆瓦级高速永磁同步电机偏心状态下电机性能及转子振动特性分析

在电机运行过程中,气隙偏心是一种常见的故障状态,会危害到电机的安全可靠运行,而该问题在大容量高速永磁同步电机中更为严重。因此,本文以一台兆瓦级高速永磁同步电动机为例,研究了气隙偏心对电机电磁性能以及其引发的不平衡磁拉力对转子振动特性的影响。首先,推导了静、动以及混合偏心状态下的不平衡磁拉力表达式。然后,建立了各偏心状态下的电机有限元模型,定量分析了不同偏心程度所引发的不平衡磁拉力变化情况。在此基础上,计算了电机转子系统的动力响应,详细讨论了各种偏心对转子系统轴心轨迹和电磁性能的影响。结果表明,不同偏心状态下不平衡磁拉力存在明显差异,在混合偏心时动偏心会削弱静偏心对转子振动的影响,偏心将增加气隙磁密的偶次谐波且增大转矩脉动。

基于桨距角控制的永磁风电机组高电压穿越控制策略

为解决传统永磁风电机组高电压穿越控制策略存在超速脱网风险问题,提出一种基于桨距角控制的高电压穿越控制策略。高电压穿越期间,首先,按照并网要求向电网提供无功支撑;其次,考虑转子转速限制,当转子转速达到参考值时启动桨距角控制,抑制转子转速上升;最后,通过仿真试验,验证了所提控制策略的有效性。基于桨距角控制的永磁风电机组高电压穿越控制策略,既能向电网提供无功支撑,又能避免超速脱网。

A sensorless efficiency test system for a high-speed permanent magnet synchronous motor

We present a sensorless efficiency test system with energy recovery for a high-speed permanent magnet synchronous motor(PMSM). In the system, two identical high-speed PMSMs are used as the motor under test(MUT)and the load machine(LM),respectively.A new sensorless vector control(VC) method based on a hypothetical reference frame is presented to control both the MUT and the LM.Also,a regenerating unit is used to implement energy circulation to save energy.Experiments were carried out on a prototype, with a digital controller based on the TMS320 F28335, to verify the adequacy of the sensorless VC method.As a result,the efficiency test system achieves the load test at the speed of 21000 r/min without any reduction equipment. During the test, the energy regenerated by the LM could be fed back to the MUT by the regenerating unit, and 81.31% electrical power was saved.In addition, with the proposed sensorless VC method,both the MUT and the LM can work at i_d = 0 without a position sensor.