Novel Switched Flux Permanent Magnet Machine Topologies

This paper overviews various switched flux permanent magnet machines and their design and performance features,with particular emphasis on machine topologies with reduced magnet usage or without using magnet,as well as with variable flux capability.

Hybrid Excited Permanent Magnet Machines for Electric and Hybrid Electric Vehicles

This paper reviews various hybrid excited(HE)machines from the perspective of location of PM and DC excitation,series/parallel connection of PM and DC excited magnetic fields,and 2D/3D magnetic fields,respectively.The advantages as well as drawbacks of each category are analyzed.Since an additional control degree,i.e.DC excitation,is introduced in the HE machine,the flux weakening control strategies are more complex.The flux weakening performance as well as efficiency are compared with different control strategies.Then,the potential to mitigate the risk of uncontrolled overvoltage fault at high speed operation is highlighted by controlling the field excitation.Since additional DC coils are usually required for HE machines compared with pure PM excitation,the spatial confliction inevitably results in electromagnetic performance reduction.Finally,the technique to integrate the field and armature windings with open-winding drive circuit is introduced,and novel HE machines without a DC coil are summarized.

Electromagnetic Performance Analysis of Flux-Switching Permanent Magnet Tubular Machine with Hybrid Cores

The performance of traditional flux switching permanent magnet tubular machine(FSPMTM)are improved by using new material and structure in this paper.The existing silicon steel sheet making for all mover cores or part of stator cores are replaced by soft magnetic composite(SMC)cores,and the lamination direction of the silicon steel sheet in stator cores have be changed.The eddy current loss of the machine with hybrid cores will be reduced greatly as the magnetic flux will not pass through the silicon steel sheet vertically.In order to reduce the influence of end effect,the unequal stator width design method is proposed.With the new design,the symmetry of the permanent magnet flux linkage has been improved greatly and the cogging force caused by the end effect has been reduced.Both 2-D and 3-D finite element methods(FEM)are applied for the quantitative analysis.

Reduction of Cogging Torque in Permanent Magnet Flux-Switching Machines

Permanent magnet flux-switching machine (PMFSM) is a relatively new structure. Available literatures mainly focused on its general design procedure and performance analysis. In this paper, Finite Element Method (FEM) is taken to ana-lyze various design techniques to reduce the cogging torque in a prototype 12/10-pole PMFSM.

Quantitative Comparison of Electromagnetic Performance of Electrical Machines for HEVs/EVs

In this paper,various types of sinusoidal-fed electrical machines,i.e.induction machines(IMs),permanent magnet(PM)machines,synchronous reluctance machines,variable flux machines,wound field machines,are comprehensively reviewed in terms of basic features,merits and demerits,and compared for HEV/EV traction applications.Their latest developments are highlighted while their electromagnetic performance are quantitatively compared based on the same specification as the Prius 2010 interior PM(IPM)machine,including the torque/power-speed characteristics,power factor,efficiency map,and drive cycle based overall efficiency.It is found that PM-assisted synchronous reluctance machines are the most promising alternatives to IPM machines with lower cost and potentially higher overall efficiency.Although IMs are cheaper and have better overload capability,they exhibit lower efficiency and power factor.Other electrical machines,such as synchronous reluctance machines,wound field machines,as well as many other newly developed machines,are currently less attractive due to lower torque density and efficiency.

Recent Advances in Variable Flux Memory Machines for Traction Applications: A Review

This paper overviews the recent advances in variable flux memory machines(VFMMs)for traction applications with particular reference to newly emerged machine topologies and related control strategies.Due to the use of flux memorable low coercive force(LCF)magnets,the air-gap flux of VFMM can be flexibly varied via a magnetizing current pulse.Thus,the copper loss associated with the flux weakening current and high-speed iron loss can be significantly reduced,and hence high efficiency can be achieved over a wide speed and torque/power operation.These merits make VFMM potentially attractive for electric vehicle(EV)applications.Various novel VFMMs are reviewed with particular reference to their topologies,working principle,characteristics and related control techniques.In order to tackle the drawbacks in the existing VFMMs,some new designs are introduced for performance improvement.Then,the electromagnetic characteristics of an exemplified EV-scaled switched flux memory machine and various benchmark traction machine choices,such as induction machine,synchronous reluctance machines,as well as commercially available Prius 2010 interior permanent magnet(IPM)machine are compared.Finally,the key challenges and development trends of VFMM are highlighted,respectively.

Development of High Torque and High Power Density Hybrid Excitation Flux Switching Motor for Traction Drive in Hybrid Electric Vehicles

This paper presents design feasibility study and development of a new hybrid excitation flux switching motor (HEFSM) as a contender for traction drives in hybrid electric vehicles (HEVs). Initially, the motor general construction, the basic working principle and the design concept of the proposed HEFSM are outlined. Then, the initial drive performances of the proposed HEFSM are evaluated based on 2D-FEA, in which the design restrictions, specifications and target performances are similar with conventional interior permanent magnet synchronous motor (IPMSM) used in HEV. Since the initial results fail to achieve the target performances, deterministic design optimization approach is used to treat several design parameters. After several cycles of optimization, the proposed motor makes it possible to obtain the target torque and power of 333 Nm and 123 kW, respectively. In addition, due to definite advantage of robust rotor structure of HEFSM, rotor mechanical stress prediction at maximum speed of 12,400 r/min is much lower than the mechanical stress in conventional IPMSM. Finally, the maximum torque and power density of the final design HEFSM are approximately 11.41 Nm/kg and 5.55 kW/kg, respectively, which is 19.98% and 58.12% more than the torque and power density in existing IPMSM for Lexus RX400h.

磁通切换永磁电机多目标优化

以磁通切换永磁电机为研究对象,利用有限元法建立准确可靠的仿真模型,并通过仿真验证其有效性.运用灵敏度分析方法找出关键参数,引入进化算法对电机参数进行多目标优化,以提高电机的电磁性能.研究结果显示,优化后的电机平均电磁转矩提升了22.1%,转矩波动和齿槽转矩分别降低了9.09%和56.90%.

Design,analysis and control of hybrid excited doubly salient stator-permanent-magnet motor

In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the stator.In theory,the mathematical model and design method of the motor are developed.The corresponding output power equation and the relationship between the flux control capability and the extended speed range are deduced in details.By using an efficient "one-step" three-dimensional(3D) finite element method,the electromagnetic performances are analyzed,in which the leakage flux outside the stator circumference and end-effect are taken into account.Based on the operation principle of the motor,the control strategy and scheme are developed and implemented experimentally.Both experimental results and finite element analysis show that the proposed motor not only maintains the advantages of doubly salient permanent magnet motors,but also offers high energy efficiency over a wide speed range,which makes the motor an interesting candidate for electric vehicles.

Optimal Rotor Poles and Structure for Design of Consequent Pole Permanent Magnet Flux Switching Machine

Permanent magnet flux switching machines(PMFSM)have attracted significant research interest and are considered as competent candidates when higher torque density is primary requirement.However,conventional PMFSMs uses excessive rare earth PM volumes which ultimately increases machine the machine weight and PM cost.Moreover,the PMs extended at the stator yoke results in stator leakage flux which degrades the performance.To suppress the leakage flux and diminish the PM volume,the consequent pole PMFSM(CPPMFSM)with flux bridges and barriers encompassing partitioned circumferential and radial magnetized PMs is proposed,thereby ensuring an alternate magnetic path for the working harmonics which improves the modulation effect and flux distribution.Moreover,the influence of the rotor pole number on seven different rotor structures namely,curved rotor,trapezoidal rotor,wide rotor tooth tip,wide rotor base width,rectangular segmented and eccentric rotors are investigated based on the electromagnetic performance and stress distribution.Finite element analysis(FEA)reveals that the 12S-13P CPPMFSM with a wider rotor base offers comparatively better electromagnetic performance.Compare to the conventional PMFSM,the proposed CPPMFSM reduces the PM volume which minimizes the overall machine cost and weight,suppresses the torque ripples by 16.49%,diminishes total harmonic distortion(THD)by 35.24%and decreases cogging torque by 32.88%.Furthermore,the torque and power density are enhanced by 7.028%and 7.025%respectively.

Flux Adjustable Permanent Magnet Machines:A Technology Status Review

Flux adjustable permanent magnet machines(FAPMMs)are a novel type of permanent magnet(PM)machines which are able to flexibly adjust the field excitation flux linkage and offer the distinctive advantages of high power density and high efficiency.They have attracted ever-increasing interests and are promising candidate machines for electric vehicle,machine-tool and aircraft applications.In this paper,the state-of-the-art of various FAPMMs are comprehensively reviewed according to three means of flux-adjustment,i.e.electrically adjusted by either auxiliary field windings or armature winding change,mechanically adjusted magnetic reluctances of flux paths,and memory machines by magnetizing/demagnetizing PMs.The corresponding flux-adjustable principles and electromagnetic characteristics are systematically elaborated and quantitatively compared.Their merits and demerits are highlighted,together with their recent developments.

Dynamic torque response analysis of IPMSM in flux weakening region for HEV applications

An over-modulation based vector control strategy for interior permanent magnet synchronous machine（ IPMSM） is proposed and investigated. The strategy increases the reference flux weakening voltage to improve efficiency in flux weakening region of IPMSMwith the same dynamic torque response performance in standard SV Mtechnique. The relationship between dynamic torque performance and the reference flux weakening voltage is also discussed. In order to achieve fast and smooth shift process,the torque response must be less than 20 ms in the parallel hybrid electric vehicle（ HEV）,according to this,modeling and experimental studies were carried out. The results show that the proposed strategy can achieve the same dynamic and steady state torque performance with higher reference flux weakening voltage,which means higher efficiency.

集成压缩机用双定子磁通切换电机的设计及优化

针对轴流压缩机系统体积大、冷却难的问题,基于6/4双定子磁通切换永磁电机,提出一种新型集成压缩机用磁通切换永磁电机(FSPMM)。首先,推导了考虑转子斜极影响的齿槽转矩解析表达,建立了气体流量轨迹模型。其次,设计E型槽FSPMM和C型槽FSPMM结构并建立有限元仿真模型,对其磁密分布、反电动势、齿槽转矩、电磁转矩及波动等电磁特性进行了计算和对比分析,结果表明E型槽FSPMM的电磁性能明显优于C型槽FSPMM的电磁性能。最后,综合考虑电磁性能和流体影响,对E型槽FSPMM的转子结构进行了优化,优化后的6/4双E型槽FSPMM的转矩波动下降了15.25%,出口流速提高到113.27 m/s,适用于多级轴流压缩机系统。

考虑交叉耦合效应的混合励磁开关磁链电机转子位置估计

针对使用高频电压注入法估计混合励磁开关磁链永磁(HESFPM)电机转子位置时,由于直轴和交轴之间的交叉耦合效应使得转子位置估计精确度降低的问题,提出了一种对交叉耦合效应进行角度补偿的HESFPM电机励磁绕组高频电压注入位置估计方法。通过电枢绕组α、β轴高频电流响应估计转子位置,分析了交叉耦合效应对所提出的高频电压注入位置估计精确度的影响,通过离线方法测量出该效应导致的交叉饱和角,并进行无位置传感器控制在线角度补偿。最后,通过12槽10极HESFPM样机进行实验验证,实验结果表明电机运行在不同转速、负载工况下,所提方法能够有效减小位置估计直流偏置误差,具有良好动态跟随性能。

混合励磁交替极永磁电机多谐波调磁技术研究

高磁能永磁材料是电机实现高转矩/功率密度的前提条件,但其高矫顽力等特性导致电机弱磁困难,限制其在航空航天等高速场合的应用。针对此问题,该文提出一种混合励磁交替极永磁游标电机(hybrid excited consequent pole permanent magnet vernier machine,HE-CPPMVM)。该电机的转子采用CPPM结构,定子齿上同时绕有集中电枢绕组和直流励磁绕组。无励磁电流时,旋转的永磁场经定子齿的调制后与电枢反应谐波相互作用实现机电能量转换;施加励磁电流时,定子励磁绕组通电后可产生静止励磁磁场,经CPPM转子凸极铁芯调制后与电枢反应谐波相互作用可灵活调节电机磁场。该文介绍该电机的结构特征,建立交替极永磁场、励磁磁场和定转子磁导模型,阐述工作谐波特性,揭示其多谐波工作调磁原理。加工原理样机并进行测试,验证调磁原理的有效性。

模块化多单元磁通切换电机设计与特性分析

该文提出一种具有高转矩密度、低转矩脉动的新型模块化多单元磁通切换(modularelementaryfluxswitching permanentmagnet,ME-FSPM)电机结构,研究槽极配合对电磁特性的影响。基于气隙磁场调制原理,从永磁磁场调制的角度阐明ME-FSPM电机气隙磁导调制系数对永磁磁密调制谐波影响规律。由于轴向模块配合与集成环形绕组拓扑,ME-FSPM电机不同槽极配合下具有高绕组因数特征,进而针对性的定义气隙磁导调制系数是决定永磁磁链基波幅值的关键参数。依据气隙磁导调制系数模型,揭示电负荷恒定下转子极数与电磁转矩变化规律。基于气隙磁密分布规律,分析模块配合下齿槽转矩抑制原理,依据槽极配合选择实现齿槽转矩基波抵消以及输出转矩提升,提出ME-FSPM电机槽极配合选择方法。最后,在6槽ME-FSPM电机结构下,选择6槽/7极和6槽/8极结构具有良好的转矩特性,并通过仿真与实验验证理论方法的合理性与有效性。

基于改进滑模观测器的无位置传感器AFFSPM电机模型预测磁链控制

为了提高轴向磁场磁通切换永磁(axial field fluxswitching permanent magnet,AFFSPM)电机无位置传感器位置检测精度,同时抑制该电机的转矩和磁链脉动,该文提出一种基于改进滑模观测器(sliding mode observer,SMO)的无位置传感器AFFSPM电机模型预测磁链控制方法。首先,基于传统滑模观测器,设计边界层可随滑模面误差自调节的反正弦饱和函数,削弱系统抖振,改善系统稳态性能;接着,将扩展卡尔曼滤波器及幅值补偿环节代替单一低通滤波器,并通过内嵌二阶广义积分器的软件锁相环估算转子位置角和速度,消除位置角补偿,提高位置观测精确度;最后,将估算的转子位置角和速度反馈到模型预测磁链控制模块,完成无位置传感器控制。该文通过理论推导、仿真与实验研究验证所提出的控制策略可有效提高AFFSPM电机无传感器控制的稳态和动态性能。

混合永磁记忆电机全速域分段调速方法

针对钻机顶驱永磁电动机电能消耗大、退磁风险高、高效率调速范围窄等问题,提出以混合永磁记忆电机(HPM-MM)为核心的新型直驱式变频顶驱系统.根据HPM-MM不同磁化状态下永磁磁链与转速的对应关系,结合永磁体在线写极与超前角弱磁协调控制,使HPM-MM在具备永磁同步电机的优良特性外,还可以实现大范围平滑调速控制.通过计算转折速度划分运行区域,将运行区域分为恒转矩低速区和恒功率高速区.低速区使电机处于正向饱和充磁状态获得最大输出转矩.高速区包括弱磁Ⅰ区和弱磁Ⅱ区,弱磁Ⅰ区通过电机低矫顽力磁钢分段调磁实现高效调速;弱磁Ⅱ区采用超前角弱磁控制,通过重新分配定子电流进一步拓宽电机调速范围.该方法有效结合了HPM-MM本体的在线调磁与驱动协调控制能力,仿真分析验证了理论结果的有效性与可行性.

双三相PMSM混合储能系统分布式转矩控制方法

为克服传统电池/超级电容混合储能系统(hybrid energy storage system, HESS)中电气或机械耦合方式下存在的多级功率不平衡、机械零件不匹配等问题,本文基于双三相永磁同步电机(permanent magnet synchronous machine, PMSM)进行HESS设计,并结合电动汽车典型运行工况提出一种分布式转矩控制方法。文中首先建立双三相PMSM混合储能系统数学模型,推演分析了电机双绕组转矩关系,设计了适用于双三相PMSM的分布式转矩控制系统。在此基础上,考虑HESS中电池组和UCs特性差异,分析了高功率、低功率以及UCs能量调节三种HESS模式下的转矩关系,并完成了高低频转矩的分频协调控制。最后,基于5kW测试平台对所提方法进行测试与分析,结果表明该系统可在全速域加速、加减载、负载扰动等多模式下实现HESS稳态和暂态功率的高性能调节,同时,磁链解耦调节环节有效增强了HESS的暂态响应能力,有效地抑制了负载扰动下的系统低频振荡。

混合励磁电机技术综述与发展展望

混合励磁电机不仅能继承永磁电机的诸多特点,而且电机气隙磁场平滑可调,电动运行时,具有起动转矩大、调速范围广的优点;发电运行时,具有较宽的电压调节能力或宽范围变速恒压输出能力,因此,具有广泛的工业应用前景。本文系统阐述了混合励磁电机的基本特点,并引入混合励磁及其混合励磁电机的基本定义,分析了混合励磁电机磁场调节的一般原理;对几种典型的混合励磁电机结构、原理以及混合励磁电机一般控制技术进行了分析,针对混合励磁电机设计、分析与控制技术的研究现状和存在的不足,探讨了混合励磁电机技术的发展趋势和研究方向。