用于简易变频器设计的新型扁平输入整流器

在制造横向磁场永磁电机（TFPM）电机之前，应确定最大转矩的波形。通过调整TEPM电机的各项几何参数，可以使电机达到其最大转矩。一种基于人工智能的最优化方法可以使得每个极间隔都获得理想的转矩波形。本文给出了一种用于优化TEPM几何参数的遗传算法，该算法同样适用于其它结构的电机。     

一种利用过渡过程响应波形进行电机参数辨识的方法

在异步电动机变频调速中，矢量控制作为一种优秀的控制方法引起广泛的研究，而矢量控制中对于电机参数的准确性要求非常高。本文介绍的一种利用电视空载时候过渡过程响应波形对异步电动机电机参数进行系统辨识的方法可以很好的解决这个问题。     

圆筒型双Ω定子横向磁通永磁电机建模分析

双Ω型定子横向磁通永磁直线电机在同一个电枢上通过整合两组定子铁心的方式使得其结构更加紧凑,其空间利用率高、效率高、功率密度大。在分析新型双Ω定子横向磁通永磁直线电机的基础上设计了两类圆筒型的双Ω定子横向磁通永磁电机,采用有限元分析方法(FEA)分别对两类电机的气隙磁密波形、反电势、磁链及电磁转矩参数进行比较分析。结果表明:三相结构更加紧凑,适用于对电机体积限制严格、转矩高的场合;单相结构的磁通密度分布、反电势、磁链参数波形更为理想,在电机精度要求较高的场合可选择该结构。     

基于转速估计的永磁同步电机MTPA控制

由于永磁同步电机的参数易受温度、磁饱和等因素的影响而发生变化,进而影响控制系统的精度。根据电机模型提出了一种基于转速估计的最大转矩电流比控制(MTPA)算法。仿真结果表明,提出的MTPA控制策略使电机具有较好动态响应性的同时,有效地改善了电机自身参数时变性对控制系统的影响。     

基于模糊控制的电机效率优化策略

本文分析了三类电机效率优化疗式，提出了一种基于模糊控制的效率优化器，一仿真结果显示此方案能在保证电机转速、转矩基本不变的前提下，提高电机轻载时的运行效率，且不依赖于电机参数，具有良好的鲁棒性。     

单绕组磁悬浮开关磁阻电机结构优化设计

针对单绕组磁悬浮开关磁阻电机结构参数的优化问题,提出了基于相关向量机与混合粒子群优化的方法。通过有限元分析计算了电机悬浮力和转矩与结构参数的关系,构建基于相关向量机非参数模型。以电机平均悬浮力和平均转矩最大输出为优化目标,采用混合粒子群优化算法获取最优结构参数,通过对比仿真实验说明了该算法的准确性与优越性,电机性能得到明显提升。     

新型建模及优化方法在BSRM中的应用

针对电机参数优化设计问题,引入多支持向量机与混沌优化算法,优化设计磁悬浮开关磁阻电机的结构参数。采用有限元仿真建立样本空间,采用多支持向量机构建磁悬浮开关磁阻电机的非参数模型,基于该模型,以满足额定电磁转矩为条件,优化电机参数,优化目标为最大的悬浮力、最小的转矩脉动、最小的绕组间互感,最优的电机结构参数通过混沌优化算法得到。仿真结果表明,BSRM利用多支持向量机所建立的非参数模型高效且准确,采用此优化方法设计的BSRM转矩脉动小、悬浮力大、绕组间互感小。     

气隙大小对混合式步进电机转矩的影响

考察了一台两相混合式步进电机(57 BYG060)的转矩,并讨论了其与气隙长度的关系,指出随着气隙的增长,转矩的波形会恶化,高次谐波的含量开始占主要地位。可见在转矩的计算中考虑加工和成本将给混合步进电机的设计提供一个有意义的判断依据。     

改进永磁同步电机转矩控制精度的措旋

各种各样的实际因素会导致永磁同步电机在求取转矩时很难绝对精确。比如转子温升会导致磁场强度降低并使得输出转矩减小。导致转矩减小的另一种情况是在过载时铁心出现饱和。针对这样的情况，现在比较行之有效的设计思路是使用一个快速叠加速度控制环或者使用转矩传感器。但是，像绞车和注塑成型机一类的设备需要很高的转矩精度，而使用转矩传感器有诸多缺陷。本文将介绍三种不吲的改进静态转矩精度的策略。第一种策略是基于对转矩常数和磁阻转矩常数的离线辨识。这一思想在第二种策略中得以扩展．即通过转矩与转距电流之间的关系来识别电机特性。这种策略通过采用多项式方程进行计算来补偿味开环控制的不足。第三种策略是一种在线自适应转矩常数控制技术，它基于对电机电参数的观测和对转速的洲量。试验结果证实了三种策略理论的有效性。     

使用直流无刷电机的伺服系统的设计

在实际生产运用中,一般需要使用伺服系统来控制电机,以达到需要的动力。这时,使用精确的闭环控制方式,可以使电机的转矩、转速、位置等参数达到更高的精确度,能更加精确地实现系统对电机的控制。本文介绍一种使用闭环控制的直流无刷电机的伺服系统。     

Minimum torque ripple, maximum efficiency excitation of brushlesspermanent magnet motors

Permanent magnet motors are usually driven in one of two ways. Sinusoidal currents are applied when the motor has a sinusoidal back EMF, and rectangular currents are applied when the back EMF has a trapezoidal shape. If implemented perfectly, each of these drive schemes is capable of producing ripple-free torque, which is desirable in many applications. However, in reality, permanent magnet motors never exhibit perfectly sinusoidal or trapezoidal back EMFs. Moreover, the power electronics used to drive the motor often has limitations that keep it from producing the required current waveform, especially as speed or load torque increases. In addition to these limitations, a permanent magnet motor often exhibits parasitic cogging torque that directly contributes to torque ripple. This work explores the relationships between motor current and back EMF, and identifies minimum torque ripple, maximum efficiency current excitations that can be implemented with finite bandwidth power electronics (current controlled VSI)     

A novel technique for estimation and control of stator flux of a salient-pole PMSM in DTC method based on MTPF

A permanent-magnet synchronous machine (PMSM) can be controlled using the direct torque control (DTC) technique in three different ways, i.e., by controlling flux, reactive torque and rotor d-axis current. Frequently, the DTC technique controls the speed of the motor by controlling stator flux with the aim of obtaining an optimal torque. A varying flux, proportional to the torque, may be used instead of a fixed flux, resulting in a maximum torque per ampere or maximum torque per flux (MTPF). In this paper, a reference-flux-generating method is followed to achieve the MTPF. An approximate equation is then derived using numerical techniques in order to obtain the reference flux from the torque. This equation is then applied to the DTC control system in order to obtain the reference flux. The control scheme has been verified by simulation and tests on a salient-pole permanent-magnet synchronous motor.     

Dynamic response of a hydraulic servo-valve torque motor with magnetic fluids

As magnetic fluids (MF) show higher saturation magnetization and larger viscosity when exposed to a magnetic field, large damping forces or resistance will be exerted on the armature of a hydraulic servo-valve torque motor by magnetic fluids if they are filled into the working gaps of the motor. This paper focuses on the application of magnetic fluids in a hydraulic servo-valve torque motor, especially the influence of magnetic fluids on the dynamic response of the motor. After introducing the working principle of the torque motor with magnetic fluids, the dynamic mathematical models of the torque motor and magnetic fluids are presented. The torque working on the armature introduced by magnetic fluids is analyzed. In order to study the influence of magnetic fluids, dynamic response of the torque motor is simulated and tested when magnetic fluids are applied or not in the motor. Simulation and experimental results show an obvious influence of magnetic fluids on the dynamic response of the hydraulic servo-valve torque motor.     

Five-phase induction motor drives with DSP-based control system

This paper introduces two kinds of control schemes: vector control and direct torque control (DTC). These control schemes can be extensively applied to the operation of a five-phase induction motor using a fully digital implementation. Vector control of the five-phase induction motor not only achieves high drive performance, but also generates the desired nearly rectangular current waveforms and flux profile in the air-gap resulting in an improvement in air gap flux density and an increase of 10% in output torque. The DTC method has additional advantages when applied to multiphase, in this case a five-phase, induction motor. The five-phase inverter provides 32 space voltage vectors in comparison to 8 space voltage vectors provided by the three-phase inverter. Therefore, a more elaborate flux and torque control algorithm for the five-phase induction motor can be employed. Direct torque control of the five-phase induction motor reduces the amplitude of the ripples of both the stator flux and the torque, resulting in a more precise flux and torque control. A 32-b floating-point TMS320C32 digital signal processor (DSP) enables these two sophisticated control techniques to be conveniently implemented with high control precision. Experimental results show that an ideal control capability is obtained for both control methods when applied to the five-phase induction motor and further validates theoretical analysis     

Torque capability and control of a saturated induction motor over awide range of flux weakening

The first part of this paper covers an investigation of the maximum torque which an induction motor with saturated air gap inductance can generate over its permitted speed range, when voltage as well as current are limited. From the investigation, three regions of operating speed are identified, based on limiting quantities which determine the maximum obtainable torque. In each of these regions a different control strategy must be applied. When maximum torque is not required, efficiency can be optimized but this strategy should not be applied at low torque levels when good dynamic performance is required. The second part illustrates how a modified rotor flux oriented control strategy is applied to achieve full utilization of the torque capability over the whole speed range. Several measures for improving dynamic and transient behavior of the drive in the flux weakening region are suggested. Performance of the new control strategy is verified by experiments     

Improvement of low-speed operation performance of DTC forthree-level inverter-fed induction motors

A direct torque control algorithm for three-level inverter-fed induction motors is presented. Basic voltage selection methods similar to a two-level inverter provoke some problems such as stator-flux drooping phenomenon and undesirable torque control deterioration appeared, especially at low-speed operation. To overcome these problems, an algorithm with the basic switching sectors subdivided and intermediate voltage vectors applied is proposed in this paper. This algorithm basically considers applications in which direct torque-controlled induction motors are fed by three-level inverters with maximum switching frequency lowered around 1 kHz. An adaptive observer is also employed to bring better responses at the low-speed operation, by estimating some state variables and motor parameters which take a deep effect on the performance of the low-speed operation. Simulation and experiment results verify effectiveness of the proposed algorithm     

8／6极开关磁阻电机两相励磁电磁转矩分析

为了准确掌握SR电机两相励磁状态下的电磁转矩情况,针对四相8／6极SR电机,采用准线性模型,从单相励磁运行时电磁转矩入手,将单相励磁转矩计算结果扩展至两相励磁运行状态。根据四相8／6极SR电机结构特点,在一个极矩下电磁转矩的变化过程中增加了两个过渡阶段,从而推导出两相励磁运行时电磁转矩的计算公式,绘制了单相与两相励磁转矩波形图,分析了两相励磁运行特点。最终从电磁转矩计算公式和转矩波形图上验证了两相励磁是SR电机提高转矩平稳性重要方法这一结论。     

Quick response and low-distortion current control for multipleinverter-fed induction motor drives

This paper describes a PWM control method to balance two unit inverter currents and to reduce the distortion of motor currents in a multiple GTO inverter for large capacity AC variable-speed drive systems. For an 11 kW induction motor driven by a 15 kVA multiple inverter, the imbalance current can be reduced to less than 5% of the rated motor current, and the motor current waveform can be made very close to sinusoidal. The GTO switching frequency in the multiple inverter can be lowered to one-quarter of that in the single inverter. In a 2750 kVA GTO inverter drive system which was developed based on the 15 kVA multiple inverter, excellent performance is obtained including unity power factor operation at an AC power source, smooth 4-quadrant operation, and quick speed response of 85 rad/s. The quick response is realized by field-oriented control with decoupling control between torque and exciting currents, and direct control of three-phase AC currents. In the future, the multiple GTO inverter is expected to be applied to rolling mill drives instead of cycloconverters     

Control and dynamics of constant-power-loss-based operation ofpermanent-magnet synchronous motor drive system

The operational envelope of electrical machines is limited by the maximum permissible power loss of the machine at any given speed. The control and dynamics of the permanent-magnet synchronous motor (PMSM) drive operating with a maximum power loss versus speed profile is proposed in this paper. The proposed operational strategy is modeled and analyzed. Its comparison to the conventional strategy of limiting current and power to rated values demonstrates the superiority of the proposed scheme. The implementation of the proposed strategy is developed. It is achieved with an outer power loss feedback control loop. This has the advantage of retrofitting the present PMSM drives with the least amount of software/hardware effort. The PMSM drives in this case then can use the existing controllers to implement any torque control criteria, such as constant torque angle, unity power factor, constant air-gap flux linkages, maximum torque per unit current, or maximum-efficiency operation. Experimental verification of the new operational strategy is provided. The concepts presented in this paper can be applied to all other types of motor drives