PM-assisted reluctance synchronous motor/generator (PM-RSM) for mild hybrid vehicles: electromagnetic design

This paper introduces the conceptual design and finite-element method analysis of a permanent-magnet-assisted reluctance synchronous motor/generator for mild hybrid vehicles where a large constant power speed range (6:1) is required and machine volume, converter peak kVA, and battery size are the main constraints. Careful flux-barrier and permanent-magnet sizing, high magnetic saturation, and current density are the main requirements for maximum torque production with constraint volume. A specific tangential force density of 4.33 N/cm/sup 2/ is obtained. Rated (continuous) power-battery limited is 2.5 kW at 42 V dc, from 1000 to 6000 r/min. The peak torque of 140 N/spl middot/m is obtained at 202 A (rms/phase) and can be secured up to 500 r/min. Peak power is still 7.85 kW at 6000 r/min at 42 V dc with an efficiency of 90%. Preliminary results on a prototype are also available.     

Sensorless-control of the synchronous reluctance motor

In this paper a sensorless closed-loop speed control for the synchronous reluctance motor is presented. The sensorless control is based on the torque vector control algorithm. It has been implemented using a high-speed digital processor DSP96002. Experimental results for a 120 W axially-laminated synchronous reluctance motor are presented and compared with operation with a speed sensor and simulations. A base speed range of 400-1500 RPM has been achieved. The top speed was extended to 2750 RPM using flux-weakening. The drive can be applied a full-load step-change within this speed range without losing synchronism     

Performance analysis of a reluctance synchronous motor under abnormal operating conditions

In recent years, the application of reluctance synchronous motors to ac drives has been gaining importance. In this paper, the performance of such motors under abnormal operating conditions (such as voltage unbalance) is analyzed and compared to their performance under normal conditions by means of motor current signature analysis. In order to permit an objective comparison of the simulation and experimental results, the influence of the supply time harmonics and constructional asymmetries of the machine is also considered. Detailed mathematical proofs are provided to support the results. Such analysis will be helpful for understanding and identifying stator inter-turn faults unambiguously. To the best knowledge of the authors, such an analysis has not been carried out previously.     

Position-controlled synchronous reluctance motor without rotationaltransducer

This paper presents a position sensorless control scheme of a synchronous reluctance motor (SynRM) combining a high-frequency current injection method in the low-speed region and the flux estimation method based on the stator voltages in the high-speed region. The rotor has inherent saliency, and its angle can be estimated from d-axis stator current injection and the appropriate signal demodulation in a low-speed region. In the high-speed region, the rotor can be estimated by the stator flux from the voltage information. The scheme gives a robust and dynamic estimation of the rotor angle, independent of the operating conditions, including speed and load conditions. Experimental results of closed-loop speed and position control with a 3.75 kW axially laminated SynRM are given to verify the proposed scheme     

Identification of linear synchronous reluctance motor parameters

This paper deals with experimental methods for the identification of linear synchronous reluctance motor (LSRM) parameters. A magnetically nonlinear two-axis dynamic LSRM model is derived. This model accounts for the effects of slotting, saturation, cross-saturation, and the end effects. The parameters of the obtained model are not constant. They are given by the characteristics of the flux linkages, thrust, and friction force depending on the mover position and the direct (d) and quadrature (q) axis currents. These characteristics are determined experimentally by a controlled voltage-source inverter employing closed-loop current control in the d-q reference frame. The proposed model, experimental methods, and determined characteristics are confirmed through a comparison between the measured and calculated results. Two tests are performed: a test at the locked mover, and kinematic control at low speed. The effects of cross saturation under dynamic operating conditions and the effects of slotting can be clearly seen in the measured and calculated results.     

Design of a synchronous reluctance motor drive

A segmental-rotor synchronous reluctance motor is used in a variable-speed drive with current-regulated pulse-width-modulated (PWM) control. The low-speed torque capability is compared with that of an induction motor, a switched reluctance motor, and a brushless DC PM motor of identical size and copper weight. A particular point of interest is the comparison of motors of different types, all with essentially the same frame size and tested under identical conditions. The results suggest that many of the desirable properties of the switched reluctance motor can be realized with the synchronous reluctance motor but with using standard AC motor and control components. The torque capability is lower, but so is the noise level     

On-line efficiency optimization of a synchronous reluctance motor

This paper deals with an on-line optimum-efficiency control of a synchronous reluctance motor drive. The input power minimization control is implemented with a search controller using Fibonacci search algorithm. It searches the optimal reference value of the d-axis stator current for which the input power is minimum. The input power is calculated from the measured dc-bus current and dc-bus voltage of the inverter. A rotor-oriented vector control of the synchronous reluctance machine with the optimization efficiency controller is achieved with a DSP board (TMS302C31). Experimental results are presented to validate the proposed control methods. It is shown that stability problems can appear during the search process.     

A synchronous reluctance motor with a laminated rotor

Optimal tooth factors and polar overlap are obtained using numerical calculations of an in-plane magnetic field in the active volume of a synchronous reluctance motor (SRM) with a laminated rotor using FEMM 4.01 (Finite Element Method Magnetics, Version 4.01) software. Recommendations for improving the technical and economic indices of an SRM with laminated rotors at the expense of cutouts in ferromagnetic rotor packs and placing compensatory permanent magnets on the way of transverse magnetic flux closure are given.     

Sensorless vector controller for a synchronous reluctance motor

A new high-performance sensorless speed vector controller that implements the maximum torque per ampere control strategy for the inverter-driven synchronous reluctance machine is presented in this paper. It is based on a parameter-dependent technique for online estimation of rotor position and angular velocity at the control rate. The current ripple principle is used to estimate position. The estimates are fed to a conventional closed-loop observer to predict the new position and angular velocity. The very high accuracy of the sensorless control algorithm at both low and high speeds is confirmed by experimental results     

PWM逆变器——磁阻同步电动机驱动系统运行稳定性的分析

研究了由PWM逆变器供电的磁阻同步电动机的运行稳定性,导出了dq0坐标系中PWM 逆变器-磁阻电动机的小信号模型,以稳定度λ作为稳定性能的指标,应用Rout-Hurwitz判据判定系统的稳定性,并分析了电机和系统参数对运行稳定性的影响,所得结论对变频磁阻电动机的设计具有参考价值。     

Variable reluctance motor structures for low-speed operation

The static torque capability of three competing variable reluctance motors is compared in order to identify which structure is best suited for low-speed operation. Linear analysis is the basis of the comparison between a conventional switched reluctance motor, a variable reluctance motor with mutually coupled windings, and a variable reluctance motor with anisotropic rotor. End turn and multipole effects are considered. The impact of saturation is considered by comparing static torque computed with finite element models. This analysis provides the rationale for choosing one configuration over another under fixed voltage and current limit constraints. The alternative constructions are shown to have potential for significant improvement in static torque under certain conditions     

A permanent magnet‐assisted synchronous reluctance motor

Permanent magnet motors have attracted a lot of attention recently for their potential for saving energy. However, they are only used for certain applications because the magnets are expensive. This paper discusses the optimum design of the low‐cost, highly efficient magnet‐ assisted reluctance motors with a minimum amount of magnets. The motor considered in this study is a multi‐flux barrier reluctance motor. The configuration by which permanent magnets are embedded to the innermost side of the rotor to obtain maximum output with the minimum amount of magnets was evaluated through simulation and experiments with a prototype motor. As a result, we established a method for designing motors capable of realizing the same efficiency as permanent magnet motors with only one‐fourth the amount of magnets. In our experiments, we achieved a high efficiency of 94.5% with a 750‐W motor. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 142(4): 66–74, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10123     

Vector control of a synchronous reluctance motor includingsaturation and iron loss

The application of vector control to a conventional synchronous reluctance motor (VCSynRM) is presented with emphasis on the effects of saturation and iron losses. It is shown experimentally that these parasitic effects can significantly influence the performance of a VCSynRM. A synchronous reference frame steady state model of SynRM including saturation and iron losses is developed. The behavior of a vector-controlled SynRM is analyzed based on the model. It is observed that saturation and iron losses can have a significant effect on the performance of a VCSynRM. To verify the validity of the model for vector control, a digital signal processor (DSP) based vector controller was built for a 7.5 hp SynRM to experimentally evaluate performance. Experimental results concerning optimal torque/ampere and optimal efficiency operation are shown to be in general agreement with the predictions of the model     

基于Ansoft的永磁同步磁阻电机建模与仿真

采用Ansoft公司的maxwell 2D模型建立永磁同步磁阻电机模型,构建一个完整的仿真系统.通过对PMa_SynRM模型的有限元分析,得出反电势曲线,以及转子位置变化对应的转矩与磁场的分布情况,并得到最大转矩下弱磁控制角度,仿真结果为PMa_SynRM的优化设计及进一步研究提供了理论依据.     

永磁辅助磁阻同步电机性能分析

为了准确分析永磁辅助磁阻同步电机的动态特性,针对永磁辅助磁阻同步电机本体,给出一种基于有限元建模分析方法.通过有限元建模分析得出其D-Q轴磁链、自感和互感等数据,利用这些有限元分析数据推导出永磁辅助磁阻同步电机的数学模型.在此基础上为了进一步提高永磁辅助磁阻同步电机的动态转矩响应,特别设计了具有电流反馈补偿的负载转矩观测器,并对其进行了研究和建模仿真.仿真结果表明,永磁辅助磁阻同步电机具有很好的动态性能.     

车用永磁同步磁阻电机转子的优化设计

永磁同步磁阻电机充分利用磁阻转矩,有效提高了电机功率密度和降低电机成本。本文首先对永磁电机的磁阻转矩影响因素进行分析,建立了3种不同结构转子模型,利用二维有限元法对电机的重要参数进行了计算和对比分析。综合比较后,对其中一种转子结构进行了优化,通过调整直轴和交轴磁路,提高了电机磁阻转矩的比例及弱磁性能。     

Steady-state performance of a line-start synchronous reluctance motor with capacitive assistance

This paper sets forth the steady-state performance analysis of a connection scheme that improves the power factor and torque with a lower magnetizing current for a line-start synchronous reluctance motor. The machine stator winding is split into two equal halves, one connected to the mains and the other connected to a balanced capacitor. Performance of the machine is improved if the capacitor value is such that the winding to which it connected operate at or very close to resonance in the d-axis. Current in both windings contributes positively to torque production and external control circuitry is not required. Steady-state equations arising from the d–q model gives a direct insight on the operating limits and how this capacitance aids the machines torque and power factor by boosting its direct axis reactance while the quadrature axis reactance remains fairly constant. An equivalent circuit is also deduced from the steady-state equations from which an explicit expression for input impedance of the new machine can be derived. Conditions for unity-power factor at varying load conditions are also examined. A comparison with conventional single-winding synchronous reluctance motor is given. Such comparison is fair because both machines have the same amount of copper and iron. Experimental results are provided to validate the analytical results.     

同步磁阻电机混沌系统的自适应滑模控制

针对同步磁阻电机系统在特定条件下出现的混沌现象,提出一种自适应滑模控制方法,构建了同步磁阻电动机混沌系统模型.在此基础上,设计了同步磁阻电机混沌系统的自适应滑模控制器,并运用MATLAB仿真对该控制方法进行了验证.结果表明,该控制方法具有良好的稳定性、准确性与快速性.     

开关磁阻电机低速运行无位置传感器检测方法

针对开关磁阻电机低速运行方法中的传统脉冲注入法只利用非导通相电流信息,存在导通区间受限和续流影响估计精度的问题。本文对低速控制策略与无位置检测原理进行研究,提出了一种双电流斩波限PWM滞环控制的三相电流斜率差值无位置传感器检测方案。所提方案在导通区采用双斩波限PWM滞环控制,使导通区电流斩波次数增加,能够改善低速运行时的性能,并提高电流斜率差值的计算精度。与传统非导通相电流比较方法只利用非导通相信息相比,该方案增加了导通相电流计算。在计算导通相电流斜率差值后,与两非导通相形成三相电流斜率差值,从而估计电机的实时位置信息。以三相12/8结构的电机进行了相关仿真和实验验证,实验结果表明,该方案能够有效解决传统方法存在的导通区间固定和实时角度计算受续流影响的问题。     

Mover design and performance analysis of linear synchronous reluctance motor with multiflux barrier

A synchronous reluctance motor has many advantages because it has no permanent magnet, such as low back emf in high‐speed operation, maintaining performance in a high‐temperature environment, and so on. Therefore, many rotor constructions have been studied and developed. The rotor with multiflux barrier structure has the merit of easy construction and high performance. The linear synchronous reluctance motor has been developed. It is necessary to improve the performance of the mover design for industrial use, because of its low power factor. In this paper, we propose a novel configuration of mover for the linear synchronous reluctance motor, and examine the static characteristics of the motor with reluctance equalization design by means of the finite element method. From analytical results, it is demonstrated that the static characteristics of the linear synchronous reluctance motor are greatly improved by the reluctance equalization design at the iron layer in the mover. © 2002 Scripta Technica, Electr Eng Jpn, 138(4): 61–69, 2002; DOI 10.1002/eej.1139