基于转矩分配函数在线修正的开关磁阻电机转矩脉动抑制策略

针对开关磁阻电机在换相阶段由于转矩特性、电压限制、转速升高等因素而引起的转矩脉动问题,研究一种基于转矩分配函数在线修正的直接瞬时转矩控制方案。在换相的开始阶段,对前一相绕组的转矩分配函数进行在线正补偿,对后一相绕组的转矩分配函数不做处理;在换相的结束阶段,对后一相绕组的转矩分配函数实现在线负补偿,对前一相绕组转矩分配函数不做处理,从而实现电机在换相阶段总转矩脉动的抑制。为了验证该策略的可行性和有效性,以一台750 W、三相12/8极开关磁阻电机为控制对象进行仿真和实验,结果证实了提出的方案可以有效地抑制转矩脉动。     

Some considerations on torque ripple suppression in reluctance motors

Although the reluctance motors are attractive from the standpoints of simple construction and drive electronics, the relatively high torque ripple and acoustic noise are major drawbacks. These drawbacks limit motor applications. In this paper, the torque ripple suppression of the reluctance motor under the sinusoidal current drive is examined. The analysis shows that the torque ripple is caused by the spatial harmonics of inductance. One approach is based on the compensation current generated with the spatial harmonics of inductance. Another is based on the modification of rotor tooth configuration to eliminate the spatial harmonics. According to the proposed strategies, torque ripple suppression characteristics can be evaluated at the design stage of the motor. Both approaches have been verified by experiments. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 118–128, 2000     

Unified theory of torque production in switched reluctance andsynchronous reluctance motors

A method is described for calculating the average and instantaneous torque of the synchronous reluctance motor from a knowledge of the trajectory of the phase flux-linkage versus phase current [i-ψ] waveform, i.e., the same method as used with the switched reluctance motor. This allows a direct comparison between torque production in the two motors to be made. Analytical and finite-element analysis both show that the [i-ψ] loci of the synchronous reluctance motor are ellipsoidal in shape and are not limited to the first and third quadrants as in the switched reluctance motor. The [i-ψ] loci of the synchronous reluctance motor are not bounded by the magnetization curves in the same sense as in the switched reluctance motor and rely upon mutual coupling between phases for correct operation     

直接转矩控制在开关磁阻电机中的应用与研究

阐述了开关磁阻电机(SRM)直接转矩控(制DTC)策略的原理,指出直接转矩控制的核心在于电压矢量的选择及开关表的建立,给出了DTC在SRM中应用的具体实现方法。对基于直接转矩控制策略的SRM电机转矩控制进行了仿真及实验研究,仿真结果表明,这种策略能够较好地抑制转矩脉动,系统动静态特性良好,实现方法简单。     

Phase current modulation of switched reluctance motor to minimize torque ripple

This paper presents a simple technique to minimize torque ripple of a switched reluctance motor (SRM). The technique is based on the control of the sum of the square of the phase currents by using only two current sensors and analog multipliers. The control characteristics of the SRM drives are analyzed for operation of the motor in the linear region of its magnetic characteristics. The simulation and experimental results of the proposed method are given. The advantages and limitations of the proposed circuit are explained.     

Runtime data‐based characterization and torque estimation of switched reluctance motors

High‐performance control of a switched reluctance (SR) motor strictly requires an accurate nonlinear motor model as well as an appropriate control strategy. Since recent modeling methods are either complex or not accurate enough, this paper focuses on overcoming such drawdacks. An experimental method is proposed to collect useful data for modeling a 6/4 SR motor at running condition. Nonlinear modeling is done by an algorithm, which also enables simple static torque computation. The algorithm presents not only the static torque data but also an estimator model for instantaneous torque estimation during real‐time operation, which is very important for most torque control strategies. The nonlinear model is experimantally tested, and its accuracy verified. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Aspects of design optimization for multiple tooth per stator pole switched reluctance motors

Two developed computer packages are applied to the design of switched reluctance motors. Design possibilities are illustrated by focussing on two prototype multiple tooth per stator pole devices. These packages correctly allow for all the major practical effects, including magnetic saturation and core losses. Results from a typical series of runs of these packages are given, leading to general design recommendations. These cover tooth width to slot pitch ratio, split ratios and back-of-core dimensions, and are of particular utility for initial design of switched reluctance motors.     

Studies of torque ripple in a switched reluctance motor under a controlled average torque value in a low-velocity mode

In the case of adjusting the average torque value of switched reluctance motors, torque ripple is most pronounced in a low-velocity mode. In this mode, the motor phase-currents are usually forcibly limited; therefore, owing to the available voltage margin, by properly selecting the positions of phase switching, one can influence the shape of the phase-currents within certain limits and, thereby, achieve a decrease in the torque ripple. This paper considers the possibilities of reducing torque ripple using very common methods for restricting the phase-current, such as voltage control and current control. Using simulation modeling in the Matlab–Simulink environment, the best combinations of control actions are found, with which torque ripple is minimal. It is shown that, by using the first method of phase-current restriction, the reduction in torque ripple under certain conditions is achieved via a forced pulling of the range of phase-current increase due to a later switching on of the phase with a simultaneous increase in the voltage across this phase. In a number of cases, the desired effect can be achieved only owing to a certain delay in the command for switching the phase off with respect to the position corresponding to a single-switching mode. For the second method of phasecurrent restriction, the best switching conditions are found for fixed levels of current restriction determined from the desired values of the average motor torque, and independent adjusting of the switch-on and switchoff positions of its phases.     

Impact of stator windings and end-bells on resonant frequencies and mode shapes of switched reluctance motors

One of the main drawbacks of switched reluctance motors (SRMs) is vibration and acoustic noise, which limits their application. An accurate predication of the modal vibration frequencies of the SRM stator is essential in order to design a low-vibration motor and operate it quietly. Electronic techniques for noise reduction also depend on knowledge of the resonant frequencies, which depend on the mechanical structure surrounding the laminations. This paper examines the effects of the stator windings and end-bells on stator modal vibration frequencies. The error in the calculation of the resonant frequencies can be up to 20% if the influence of end-bells is neglected. The numerical computations of the stator mode shapes and resonant frequencies are validated with experimental results.     

An investigation into vibration in switched reluctance motors

Two disadvantages of the switched reluctance motor (SRM) are its torque ripple and acoustic noise. Previous work on vibration modes and resonant frequencies of the laminations of an 8-6 SRM is extended here to include the effects of the frame. Both a smooth frame and a ribbed frame are examined, and the presence of numerous additional vibratory modes in the ribbed frame demonstrated. Accelerometer tests behind a pole verify some of the theoretical predictions     

New modulation encoding techniques for indirect rotor positionsensing in switched reluctance motors

Rotor position information is essential in switched reluctance machines (SRMs) in order to generate the phase excitation pulses for optimum control of the motor. In this paper, two new methods of indirect rotor position sensing are presented. These methods are based on the modulation techniques which are commonly used in communication systems. The instantaneous phase inductance of a nonconducting phase is extracted in an encoded form using a modulator consisting of electronic circuitry. The signal is then decoded to obtain the instantaneous inductance from which the shaft position is determined. An analysis of these modulation techniques along with the implementation scheme using a microcontroller is presented in this paper     

Rotor-position sensors in the control of switched reluctance motors

The requirements on the rotor-position sensors of switched reluctance motors are analyzed. The types of sensors employed will depend on the motor speed and the control algorithm.     

Torque-ripple minimization in switched reluctance motors usingadaptive fuzzy control

An adaptive fuzzy control scheme for the torque-ripple minimization of switched reluctance machines is presented. The fuzzy parameters are initially chosen randomly and then adjusted to optimize the control. The controller produces smooth torque up to the motor base speed. The torque is generated over the maximum positive torque-producing region of a phase. This increases the torque density and avoids high current peaks. The controller is robust toward errors in the rotor position information, which means inexpensive crude position sensors can be used. Detailed simulation and experimental results are presented. The controller shows good response in both cases     

开关磁阻变档电机及其绕组切换控制策略

针对电动汽车低速大转矩以及高速恒功率运行需求,本文提出变档电机概念,以满足复杂运行工况.采用绕组在线切换的方法,获得等效普通电机与变速器集成后的输出特性,低速时电机绕组串联,每相匝数增加,实现低转速下的大转矩输出;高速时电机绕组并联,每相匝数减少,电机反电势下降,从而拓宽电机调速范围.本文以一台150 W三相12/8极...     

Winding short circuits in the switched reluctance drive

The switched reluctance drive is known to be fault tolerant, but it is not fault free. This paper takes an in-depth look at winding short circuits in this particular machine. Modeling and testing complement a theoretical analysis. Two cases need to be distinguished, one where a complete pole is shorted, and one where a few turns are shorted. Pole short circuits lead to torque reduction that can be easily compensated for with increased current. With few turns shorted, the impact on overall torque may actually be negligible, however, significant currents may circulate through the shorted turns, the worst case being with a single turn shorted with a zero resistance. These results are discussed with a view toward possible remediation schemes aside from simply turning off the faulted phase.     

非线性模型的开关磁阻电动机转矩脉动抑制

针对开关磁阻电动机SRM(Switched Reluctance Motor)转矩脉动大的问题,基于SRM的磁化特性,分析了SRM的非线性模型.采用Matlab/Simulink仿真软件,对SRM、功率变换器及其控制系统建立了动态仿真模型,并用模糊控制器对SRM的关断角进行实时补偿,实现SRM关断角自动调节,达到减小转矩脉动的目的.仿真实验中,转矩脉动系数从补偿前的0.673 0降低到补偿后的0.257 4,证明了该方法的可行性和有效性,为实际SRM控制系统的设计和调试提供了有效的手段和工具.     

单绕组磁悬浮开关磁阻电机的原理与解耦控制

针对瞬时悬浮力与瞬时转矩非线性、强耦合的特点,研究了一种新型单绕组磁悬浮开关磁阻电机的运行机理,提出瞬时悬浮力与平均转矩分相产生的双相导通解耦控制策略。构建单绕组磁悬浮开关磁阻电机相周期内悬浮力与转矩的全角度数学模型,基于悬浮力有效产生区间内平均转矩为零的特点,提出双相导通运行策略,并以提高悬浮力响应速度及电机动态运行性能为目标,给出了电流斩波幅值和关断角的优化控制方法。针对12/8极实验样机,开展相关的仿真与实验研究,结果表明了双相导通解耦控制策略的有效性与优越性,闭环系统具有良好的动静态性能。     

开关磁阻电动机最小电感的计算和分析

对开关磁阻电动机最小电感的近似解析算法进行了分析。建立多种模型，综合采用解析法和二维、三维有限元数值方法计算最小电感值，并对解析计算法中的一些计算公式提出了合理、较精确的改进。结果表明，该改进算法是一种考虑端部效应较准确的计算最小电感的解析算法。     

New converter configurations for switched reluctance motors wherein some windings operate on recovered energy

Two new converter configurations for switched reluctance motors are proposed in which some motor windings are energized using recovered energy from remaining windings. The working principle and various operating modes are discussed in detail. Block diagrams explaining flow of energy are given. Simplified analysis is given and expressions for recovered power are derived. Techniques for designing the drive using a minimum number of components are discussed. Use of bleeder or charger circuits (if necessary) to get balanced output from all the phases is explained. Lastly, experimental results are also included. The proposed converters have been found to be more efficient, less complex, and cost effective.