Uncontrolled generator operation of interior PM synchronousmachines following high-speed inverter shutdown

Interior permanent magnet (IPM) synchronous machine drives are vulnerable to a special fault mode when gating is suddenly removed from the inverter switches during high-speed operation. The resulting IPM machine operation as a generator in combination with an uncontrolled rectifier must be properly understood and accounted for in the machine design to avoid damage to either the machine or inverter. An approximate closed-form solution is derived in this paper which relates the resulting machine phase current (and torque) to the IPM machine parameters, the DC-link voltage and the rotor speed. The resulting operating characteristics are particularly interesting for IPM machines that have been designed with inductance saliency ratios greater than 2 (i.e., high-saliency machines). The validity of the approximate solution is confirmed using dynamic simulation results, and the implications of these results for the machine designer seeking to minimize or eliminate the impact of this undesired operating mode are thoroughly discussed     

Design Tradeoffs Between Stator Core Loss and Torque Ripple in IPM Machines

High stator core losses can pose a significant problem in interior permanent-magnet (IPM) machines operating over wide constant-power speed ranges. At lower speeds, the torque ripple can be undesirably large in some IPM machine designs, contributing to acoustic noise and vibration. While previous work has addressed these two problems independently, this paper shows that the conditions for reducing stator core losses during flux-weakening operation, dominated by harmonic eddy-current losses in the stator teeth, can conflict with the conditions for reducing the torque ripple of IPM machines. It is also shown that the resulting design tradeoffs depend on the details of the IPM machine topologies that are under consideration. The appropriate IPM machine topologies that offer more favorable tradeoffs are identified to achieve the best possible compromise of high-speed stator core losses and torque ripple characteristics.      

内置式永磁电机齿槽转矩的分析研究

内置式永磁电机因其高转矩及能量密度,在许多高性能装置中得到广泛应用.但永磁电机结构的特殊性,转子永磁体和定子齿槽之间相互作用产生的齿槽转矩会引起振动和噪声,同时齿槽转矩会降低速度和位置控制系统的低速时的性能.研究了一种内置式结构永磁电机的齿槽转矩,其转子磁极永磁体分段.根据分析可知,在相同的等级及尺寸条件下,永磁体分段的内置式永磁电机(SIPMM)比传统非分段内置式永磁电机(IPMM)的齿槽转矩低得多,然后利用有限元软件Maxwell 2D计算分析比较了SIPMM与IPMM的齿槽转矩.此外,还分析了两种不同转子结构的内置式永磁电机的齿槽转矩情况.     

Identification of machine parameters of a synchronous motor

This paper presents a method for estimating the machine parameters of a synchronous motor. The presented method is equally applicable for a wound field synchronous motor, synchronous reluctance motor, or permanent magnet (PM) synchronous motor, both the interior and surface-mount types. The method works particularly well for machines having a significant amount of space harmonics, such as synchronous reluctance and interior PM (IPM) machines, where the harmonics are predominantly the slot harmonics. It is also well suited for surface PM machines operating under saturation, where the harmonics are saturation-induced. The presence of these harmonics makes the parameter identification difficult. Most of the methods presented so far in the literature have failed to properly identify machine parameters in the presence of space harmonics. In this paper, the machine parameters, identified by using a proposed algorithm, are compared with the finite element and the experimental results to demonstrate the effectiveness of the presented method. Both interior PM and surface PM machines are considered.     

Control of high-performance interior permanent magnet synchronousdrives

Control strategies for an interior permanent magnet (IPM) machine suitable for field weakening are considered. Different control approaches that identify a robust and fast torque control scheme are investigated. A flux-oriented frame based on a flux observer is chosen. An allowable operating area in the state plane is selected, and the related boundaries are implemented in the control scheme. Simulated behavior is given, together with the experimental behavior obtained with a prototype drive     

考虑磁路交叉饱和的内置式永磁同步电动机调速控制

内置式永磁同步电动机由于在结构上气隙小,交直轴电感参数差异大,因此其控制性能受参数影响敏感.由于内置式永磁同步电动机的这个特点,它在其整个控制区域,即恒转矩区域和弱磁运行区域,都必须要考虑磁路交叉饱和对电机参数的影响.文章建立了考虑交叉饱和的永磁同步电动机暂态有限元模型,通过有限元模型和修正的电感计算方法对考虑交叉饱和情况下的电机d轴和q轴电感进行了分析计算.并利用有限元模型对电机最佳电流控制角、输出转矩及弱磁控制性能等进行分析.最后用求得的电感参数用于控制并与直接采用有限元方法的分析结果进行比较验证,实验结果表明两者完全吻合.     

Five-Phase Interior Permanent-Magnet Motors With Low Torque Pulsation

High torque pulsation is a major disadvantage of most interior permanent-magnet (IPM) motor configurations. Choosing the proper number of stator slots and winding distribution as well as increasing number of phases are among the possible solutions for reducing torque pulsation. In this paper, five-phase IPM motor with fractional-slot stator is studied. It is shown that despite other IPM motors, the new five-phase IPM motor with fractional slot has a very low torque pulsation. For comparison purposes, a five-phase IPM motor with common configuration is also considered. It is shown that the torque pulsation of the proposed fractional-slot five-phase IPM motor is much lower than the conventional five-phase IPM motor. Nonlinear finite-element method is used to analyze different machine configurations. A prototype four-pole five-phase IPM motor with 15 stator slots has been built and is used for experimental verification     

高密度IPM电机最大电动运行能力评估

介绍针对高密度IPM电机存在的磁路饱和问题,介绍一种基于饱和电感参数模型评估IPM牵引电机最大电动运行能力的方法,并应用该方法预测了一台IPM牵引电机样机的最大电动运行能力。有限元分析和实验测试结果证实了方法的有效性。     

Impact of saturation and inverter cost on interior PM synchronousmachine drive optimization

This paper discusses cost-optimized interior permanent-magnet (IPM) synchronous machine drive designs and the impact that magnetic saturation and inverter cost have on their performance and design optimization. Cost-optimized designs for IPM machines and combined machine-inverter systems are compared for an automotive starter/alternator application. The optimization is performed twice, once with a linear lumped parameter model, and again using a nonlinear saturating model. The saturating model produces cost-optimized IPM machines that have lower saliency ratios, larger volumes, and more magnet material than the linear nonsaturating designs, but the saturating model designs are electromagnetically realizable, unlike the linear model designs. The inclusion of inverter cost in the drive cost optimization has a significant impact on the machine design, exchanging a larger and more expensive machine for lower power electronics costs made possible by reduced inverter current     

Analysis of Rotor Core Eddy-Current Losses in Interior Permanent-Magnet Synchronous Machines

This paper presents the results of an investigation focused on the rotor core eddy-current losses of interior permanent-magnet (IPM) synchronous machines. First, analytical insight into the rotor core eddy-current losses of IPM machines is developed. Next, major design parameters that have the most significant impact on the rotor core eddy-current losses of IPM machines are identified. Finite-element analysis results are then presented to compare the predicted eddy-current losses in the machine core of IPM machines with one- and two-layer rotors coupled with concentrated- and distributed-winding stators. It is shown that the lowest total eddy-current losses in the machine core are achieved using a combination of distributed stator windings and two magnet layers per rotor pole, whereas minimizing only the rotor core eddy-current losses favors replacement of the rotor with a single-layer configuration.      

一种IPM同步电机的在线参数估计方法

介绍了一种内埋式永磁（IPM）同步电机的在线参数估计方法。该方法基于带有饱和的最大转矩／安培轨迹，提高了电机驱动的效率。同时，消除了参数的交叉耦合，使参数估计具有鲁棒性。模型与闭环观测器相结合改善了参数估计。仿真和实验结果证实了方法的可行性。     

径向和切向结构永磁同步发电机的比较研究

针对径向结构和切向结构永磁同步电机结构上的不同,分析了转子加工和装配方面的差异。利用磁路和有限元的计算方法,探讨了两种电机在发电状态下的性能差别,研究了产生这些区别的原因。指出:径向结构永磁同步发电机的电压调整率、谐波失真率小于切向结构永磁电机,外特性较切向结构电机硬;其运行的稳定性要大于切向结构电机;漏磁较小,转子装配工艺简单。     

Influence of Rotor Geometry of an IPM Motor on Sensorless Control Feasibility

The sensorless control technique based on the superimposition of a high-frequency stator voltage is commonly used to detect the rotor position of a synchronous interior-permanent-magnet (IPM) motor. This technique is effective at zero and low motor speed, where back electromotive force is null or extremely low. Then, the accuracy of the rotor-position detection depends strictly on the rotor saliency, that is, on the geometry of the IPM rotor. This paper aims to determine some IPM rotor-design criteria so as to improve the sensorless rotor-position detection. Since the design has to be effective in different operating conditions, both saturation and cross-coupling effects have to be taken into account. It is found that the effectiveness of the sensorless rotor-position detection can be improved by means of a proper design of the IPM motor geometry even under heavy operating conditions     

Application of bi-state magnetic material to automotive offset-coupled IPM starter/alternator machine

This paper investigates a new approach to designing high-speed interior permanent-magnet (IPM) synchronous machines using a bi-state soft magnetic material. The bi-state material can have its normally high magnetic permeability permanently reduced in localized regions to that of air by means of heat treatment. This new work significantly expands a previous investigation by considering offset-coupled IPM machines that make it possible to significantly increase the rotor speed while retaining all of the other specifications of the 6-kW starter/alternator application. Lumped-parameter models, Monte Carlo optimization, and both electromagnetic and structural finite-element analysis are used to develop new offset-coupled IPM machine designs with the new material at speeds of 40 000 r/min or higher. Results from this work demonstrate that the bi-state material offers a promising approach for designing high-speed IPM machines that offer weight and volume advantages compared to their lower speed counterparts at comparable system cost.     

Static and dynamic behavior of saturation-induced saliencies andtheir effect on carrier-signal-based sensorless AC drives

This paper analyzes the origin and the behavior of saturation-induced saliencies in induction machines, and their influence on carrier-signal-injection-based sensorless techniques. The modeling of saturation-induced saliencies is necessary for the estimation of flux position, while the minimization of their influence is desired for the estimation of rotor position. Specifically focusing on rotor position estimation, there are two ways to achieve this minimization, the first being the use of a machine design that reduces the magnitude of the undesired saturation-induced saliencies and the second being the compensation in the estimator of the undesired saturation-induced saliencies. The modeling of saturation-induced saliencies, not only statically, but also dynamically, i.e., when the operating point of the machine changes, is addressed by this paper     

Flux-Weakening Regime Operation of an Interior Permanent-Magnet Synchronous Motor Drive

The interior permanent magnet (IPM) synchronous motor is compatible with extended-speed-range constant-power operation by means of flux-weakening control. Flux weakening uses stator current components to counter the fixed-amplitude magnetic airgap flux generated by the rotor magnets, performing a role similar to field weakening in a separately excited dc motor. The nature of current regulator saturation caused by the finite inverter dc source voltage is described, marked by premature torque and power degradation at high speeds in the absence of flux-weakening control. This is followed by presentation of a new flux-weakening control algorithm developed as a modification of an established feedforward IPM torque control algorithm described previously in the literature. Attractive features of this new algorithm include smooth drive transitions into and out of the flux-weakening mode, fast response, as well as automatic adjustment to changes in the dc source voltage. Simulation and empirical test results from a 3-hp laboratory IPM motor drive are used to confirm the constant-power operating envelope achieved using the new flux-weakening control algorithm.     

航空高速双绕组无刷直流电机的建模仿真

为了研究航空高速双绕组无刷直流电机(DW-BLDCM)的工作特性和各种控制策略的合理性,利用Simulink和电气系统模块库相结合,采用模块化的方法,对DW-BLDCM调速系统进行了建模和仿真。该方法针对带斩波的脉宽调制(PWM)逆变器驱动高速DW-BLDCM建模分析的难点,将电机的数学模型与电路拓扑模型相结合,从而有效地解决了带电力电子装置的复杂电机控制仿真问题。仿真结果符合理论分析,并给出了相应的试验结果,结果验证了该方法的有效性和可行性,为航空高速DW-BLDCM伺服控制系统的设计、开发和调试提供了一个有效的平台。     

利用串级联接调速原理的变极起动绕线转子感应电动机

提出了一种起动时利用转子串级联接调速原理的新型变极起动无刷绕线转子感应电动机。这种新型电机依靠定子绕组切换不同的极数来进行起动和正常运行两种工作状态的转换。与常规变极起动电动机不同的是，新型电机按极数q1起动，但其同步转速对应极数为q1 q2，运行极数为p，因此只要选取p=q1 q2，起动时可以直接起动至额定工作转速，从而避免了起动完毕转换至额定工作状态时可能产生的冲击电流。又因为转子上无滑环电刷，从此新型电机可以做到运行性能好于普通绕线转子电机。文中分析了新型电机的工作原理，并进一步提出了其单绕组实用方案构成思路，给出了6极起动，8极运行的一种单绕组方案，试验测定了其在起动极和正常运行极下的转矩-转速曲线。     

基于DSP的感应电动机直接转矩控制系统设计

提出一种基于TMS320LF2407A IPM架构的交流感应电动机直接转矩控制系统数字化实现方案,主电路由整流电路、中间直流通路和逆变电路构成。逆变电路采用新型电力电子器件智能功率模块,使用PWM控制,控制器采用片上资源丰富的高速(40MIPS)数字信号处理器(DSPTMS320LF2407A),该控制系统不仅结构紧凑,体积小,而且可靠性高,缩短了研发周期和费用。给出了系统硬件结构和软件设计,并对某一具体参数的异步电动机进行了实验研究。正确的定子电流、转矩、磁链、速度响应实验波形表明,系统具有良好的动静态性能,所提方案是可行的。     

A method for dynamic simulation of air-gap eccentricity ininduction machines

In this paper, a method is proposed which enables the simulation of the air-gap eccentricity in induction machines. The method is based on the coupled magnetic circuit approach. The model is derived by means of winding functions, and no symmetry in windings layout is assumed. The parameters of the model are calculated directly from the geometry and winding layout of the machine. The effect of eccentricity is included in calculation of machine inductances. It is shown that by proper modeling of the induction motor it is possible to determine the effect of eccentricity on the machine startup, whether the machine is running off a sinusoidal supply or a converter. Theoretical foundations of the technique, as well as the detailed differential equations describing the machine performance under rotor eccentricity are presented