【作者】 李春艳；

【导师】 程树康； 寇宝泉；

【作者基本信息】 哈尔滨工业大学 ， 电机与电器， 2010， 博士

【摘要】 永磁同步电机具有体积小、重量轻、效率高、功率因数高、控制特性好等优点,近年来在各个领域获得了广泛的应用。但由于永磁同步电机通常采用稀土永磁体励磁,磁场调节困难,恒功率运行范围小,限制了其应用。传统永磁同步电机通常采用增大直轴去磁电流、利用电枢反应的去磁作用实现弱磁,但这种方法会使绕组铜耗增加,导致驱动系统效率降低,并可能引起永磁体的不可逆退磁。因此,深入进行具有宽广恒功率运行速度范围的永磁同步电机本体结构与弱磁控制方法研究,是目前电机及其控制领域的重要课题。本文首先提出了基于变磁阻磁场调节机理的永磁同步电机(VMRPMSM)方案,阐述了该新型永磁同步电机的结构,建立其空载等效磁路模型,计算了磁路中各部分的磁阻,探讨了非磁性体的磁阻以及研究磁阻跟随非磁性体形状参数变化的规律;然后,根据磁路计算的气隙磁通和绘制电机弱磁过程的相量图,分析了基于变磁阻磁场调节机理的永磁同步电机的弱磁机理。永磁体在槽中的位置决定了永磁体产生磁通所经过路径的磁阻,进而决定了气隙磁密的大小,而永磁体的位置是由所受合力确定的。本文依次分析了作用在永磁体上的离心力和摩擦力;构建了永磁体受力分析模型,分析了永磁体位于槽中不同位置的受力;应用有限元方法从永磁体位于槽中位置、非磁性体的形状、电机饱和、永磁体厚度和材料性能以及气隙长度五个方面重点研究了磁场力的变化规律,探讨了非磁性体形状对磁场力的影响。在电机转速变化的过程中,永磁体的受力状态是不同的。本文在分析了永磁体向上运动(电机升速过程)和永磁体向下运动(电机降速过程)过程中运动的永磁体受力差异的基础上,探讨了永磁体在槽中的运动规律与气隙磁场调节特性。研究了空载气隙磁密和空载反电势跟随主副永磁体之间的距离s的变化规律以及在电机升速和降速两个过程中的差异,并进行了样机的空载反电势测试;应用有限元方法仿真分析了弱磁效果,通过实验测试的方法研究了电机在弱磁过程中的性能。与传统永磁同步电机不同,由于基于变磁阻磁场调节机理的永磁同步电机转子中永磁体在槽中分段并有运动的特性,因此通过分析电机的漏磁系数与电感系数的变化规律,可为VMRPMSM的设计提供理论依据。本文分析了漏磁系数的影响因素,并从气隙长度、隔磁桥长度、永磁体尺寸及材料性能、永磁体运动和非磁性体形状五个方面研究了极间漏磁系数的变化规律。从电感公式推导和不同激励下的磁力线分布出发,研究了影响基于变磁阻磁场调节机理的永磁同步电机的直交轴电感的主要因素,并应用有限元方法分别从永磁体厚度、隔磁桥尺寸、电机饱和状态、非磁性体形状以及永磁体运动五个方面研究了电机的直交轴电感参数的变化规律。在电机参数分析的基础上研究了电机参数变化对弱磁性能的影响。理论分析和实验研究表明,本文提出的基于变磁阻磁场调节机理的永磁同步电机方案,具有弱磁方法简单、转速调节容易以及系统效率高等特点,为永磁同步电机驱动系统调速性能的提高提供了一种新的行之有效的方案。更多还原

【Abstract】 Permanent magnet synchronous motor (PMSM) which takes the advantages of small capacity, light weight, high efficiency and good control characteristics gets more and more applications in each field in recent years. However, the excitation of PMSM cannot be adjusted which make PMSM take a narrow constant power operation range and limit the applications. Flux weakening for traditional PMSM is accomplished by increasing the d-axis current and utilizing the armature reaction. But this method brings more copper loss, reduces the effiency of the driving system and takes the risk of demagnizting inreversibly. So taking further research on the motor structure which has wide constant power operation range and flux weakening method is still an important topic of motor and control field at the present time.We firstly present a scheme of a variable magnetic reluctance PMSM (VMRPMSM) based on the field adjustment. We formulate the structure of the VMRPMSM and then build the no-load equivalent magnetic circuit model. We calculate magnetic reluctance of each component in the magnetic circuit and research on the magnetic reluctance of the nonmagnetic conductor and the variable rule between the magnetic reluctance and the shape of the nonmagnetic conductor; then we analze the flux weakening principle of VMRPMSM according to magnetic circuit calculation of the airgap magnetic flux and the phasor diagram of the flux weakening process for the motor.The position of the permanent magnet in the slot determines the magnetic reluctance which passed by the magnetic flux produced by the permanent magent. But the position of the permanent magnet is dicided by the resultant force on the permanent magnet. We analyze the centrifugal force and friction force in turn and emphasize on the electromagnetic force. We build the force model of the permanent magents and analize the electromagnetic force that the permanent magents are in different position of the slot. We use finite element method to research on the variable rule of the electromagnetic force from the aspects of permanent magnet position, the shape of nonmagnetic conductor, motor saturation, charge magnetism length of PM, PM material performance and airgap length, especially for the effecto of the nonmagnetic conductor to the electromagnetic force.In the process of speed vaiation, we analyze the motion law of permanent magnet in the slot and the regulating performance of the airgap magnetic field based on the difference analysis of force on permanent magnet between the raising and reducing speed of the motor. We research on the relationship between the no-load air gap magnetic density and the back electromotive force (EMF) and s which is the distance between the main and sencondary permanent magnets, and analyze the difference of in the raising and reducting speed process of the motor, and test in the prototype. We use finite element method to simulate the result of flux weakening and research on the performance in the flux weakening process.The permanent magnet of the new PMSM divides into two parts in the PM slot, which is different from the traditional PMSM, and we analyze the interpolar leakage coefficent and inductance in order to design the new PMSM better. We analyze the influencing factor of leakage flux according to the definition and research on the variation law of the interpolar leakage coefficent from the aspects of airgap length, magnetic bridge length, PM size, PM movement, the shape of nonmagnetic conductor and PM material. We research on the influencing factor of inductance according to the formular and the magnetic flux distributions in different excitations and use finite element method to research on the variation law of inductance from the aspects of thickness of PM, magnetic bridge size, current satruration, the shape of nonmagnetic conductor and PM movement. Based on the analysis of parameters we research on the effect of parameters variation of the motor to the flux weakening performance.The theoretical analysis and the experimental research indicate that the variable magnetic reluctance PMSM based on the magnetic field adjustment take the features of easy flux weakening control method, easy speed adjustment and high system efficiency which provides a new and effective programme for increasing the performance of speed regulation for the PMSM driving system.更多还原