在线转矩分配函数控制开关磁阻电机策略分析

开关磁阻电机(SRM)因双凸极结构,其内部磁场非线性导致运行过程中会产生较大的噪声和转矩脉动。根据开关磁阻电机数学模型,以四相8/6极SRM作为研究对象,用Matlab/Simulink搭建基于在线TSF策略的转矩脉动控制系统模型。系统将实时转矩跟踪参考转矩,将不确定性因素进行整体逼近减小误差,实现在线TSF控制。仿真结果表明,所提系统建模方法能有效地抑制转矩脉动,并增加其稳定性,为实际电机控制系统的设计提供新的思路及参考依据。     

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。     

A current modulation scheme for direct torque control of switched reluctance motor using fuzzy logic

The paper addresses a fundamental control issue in switched reluctance motor (SRM) drives — the torque ripples. Normally, torque ripple minimization is achieved by using a look-up tables, i.e., the look-up tables uses stored magnetic characteristics to provide the reference current, on-angle, and off-angle for a given torque. A number of techniques for the generation of reference current profiles that minimize the torque ripples have also been suggested in the past. But due to highly nonlinear characteristics of the SRM, all these schemes are not fully successful. Moreover, their performance depends greatly on the accuracy of the magnetic characteristics measurements of the motor on which most of these algorithms work. Our work is primarily motivated to modulate the reference phase current pattern with the aid of fuzzy logic which is well suited to compensate for the nonlinearities of the system, so that the torque ripples are further suppressed. Performance of the proposed strategy is verified by computer simulation.     

基于A-2-SMC开关磁阻电机直接转矩控制

文中针对开关磁阻电机转矩脉动大及其控制系统难以实现快速精确调速的缺点,提出了一种自适应二阶滑模控制与直接转矩控制相结合的复合控制方案,并对该方案中的自适应二阶滑模控制器进行设计。该控制器采用超螺旋算法,同时对其增益采用自适应调节,克服了传统二阶滑模控制器增益确定依赖于扰动导数界值的缺点。仿真结果表明,文中所采用的控制方案不仅能对电机转速实现快速精确控制,而且能对电机转矩脉动进行有效抑制。     

A novel unipolar converter for switched reluctance motor

A configuration of a unipolar power converter with improved switching performance suitable for switched-reluctance motor supply is presented. The switched-reluctance motor operation principle is presented and its ideal characteristics are considered. The proposed converter is described and its operation is analyzed. The converter characteristics are studied with the aid of computer simulation. Current control of the proposed converter is considered. A prototype converter has been built to verify the analysis results and to validate the simulation. The design procedure is presented and experimental results which confirm the analysis are given and discussed     

A new torque and flux control method for switched reluctance motordrives

Switched reluctance (SR) motors have an intrinsic simplicity and low cost that make them well suited to many applications. However the motor's doubly salient structure and highly nonuniform torque and magnetization characteristics lead to the inability to excite the motor using conventional AC motor waveforms, or apply established AC motor rotating field theory to the motor. Furthermore, high torque ripple is inherent in the motor unless a torque ripple reduction strategy is employed. Thus, control of the motor is difficult and complex compared to other machines. Previous methods of control have fallen into two main categories: those which use a simplified linear model and those which account for the motor saturation. The simplified linear model schemes have the advantage of simplicity and tractability but are inaccurate in most practical SR drives, whereas the nonlinear schemes have the problem of high complexity and computational expensiveness which makes real-time implementation difficult. To overcome these problems, in this paper, a novel control method for the SR motor is derived from analysis of the nonuniform torque characteristics of the motor. The control method applies the philosophy of direct torque control (DTC). Unlike previous direct torque control schemes for the SR motor drive, the new method does not involve short flux patterns, a change of the motor winding configuration, or the use of a bipolar current drive. Thus, the scheme can be conveniently implemented on any normal type of SR motor drive. In addition, the scheme overcomes the problems associated with torque ripple control in the SR motor by regulating the torque output of the motor within a hysteresis band. Furthermore, the scheme is very simple and can be implemented in real-time with low cost microprocessor hardware     

Dual-decay converter for switched reluctance motor drives inlow-voltage applications

A modified converter topology for star-connected switched reluctance motors suitable for low-voltage applications is proposed. A dual-time-constant freewheeling circuit has been designed to improve the drive performance and efficiency over a wide range of speeds. The different modes of operation of the converter are discussed, and a comparison is made with other converter configurations     

混合外转子磁悬浮开关磁阻电机的电磁分析

为了解决飞轮储能支撑系统体积庞大以及功率损耗大的影响,提出了一种转子由8个凸极和圆盘轴向叠加而成的12/8极混合外转子结构磁悬浮开关磁阻电机(Bearingless Switched Reluctance Motor,BSRM)。该电机的特征是转子直驱飞轮,提高了装置的紧密度并且圆盘提供了悬浮力。文中详细介绍了该电机的悬浮机理和发电原理。结合ANSOFT三维有限元仿真,分析该电机的电磁特性以及转矩、悬浮力特性,结果表明:该飞轮电机具有悬浮力承载力强、易于控制、耦合小等优点。     

Control of switched reluctance drives for electric vehicleapplications

Dynamic controllers of switched reluctance drives adjust at least three variables, i.e., current amplitude, turn-on, and turn-off angles. In electric vehicle (EV) applications high efficiency of the drive over a wide speed range, wide torque bandwidth, and low torque ripple under varying DC-bus voltage conditions are important design goals. Hence, controllers of switched reluctance drives for EVs usually have a complex structure. In this paper, the demands on control accuracy of switched reluctance machine traction drives and the traction controller sampling frequency, which are necessary to take advantage of the switched reluctance machine dynamic capabilities, are discussed. To integrate the traction drive, the control commands need to be actualized with a sampling frequency of at least 100 Hz to meet the high-dynamic requirements of modern vehicle control systems, e.g., active cruise control, antislip control, and active damping of mechanical drivetrain oscillations. It is found that the switching angles have to be adjusted within one-tenth of a mechanical degree. This study shows that switched reluctance drives can fulfill all requirements needed for electric propulsion using standard microcontrollers or digital signal processors     

Highly dynamic torque control of synchronous reluctance motor

This paper presents a direct torque controller of a synchronous reluctance motor (SynRM) based on the stator current vector. The stator direct and quadrature voltages, which can generate the desired torque, are directly calculated from the machine model. A simple model without the core loss and a modified model which includes the core loss are considered in the proposed method. The results show that the fast and highly dynamic torque response can be obtained by the proposed method. The simulation and experimental results are presented to show the validity of the proposed method using the prototype SynRM     

基于转矩逆模型的SRM转矩脉动抑制研究

开关磁阻电机转矩逆模型的精度对于采用电流控制方式实现转矩控制的系统有很大的影响,文中采用经细菌群体趋药性算法优化后的最小二乘支持向量机建立开关磁阻电机的转矩逆模型,获得电流-转矩-角度特性;进而结合转矩分配函数和电流控制环构SRM转矩控制系统。通过仿真实验表明,该转矩逆模型准确地反映了电机的电流-转矩-角度特性,提高了开关磁阻电机控制系统中电流控制环的精度,并对该系统转矩脉动的抑制有重要作用。     

Indirect torque control of switched reluctance motors using iterative learning control

This paper proposes the use of iterative learning control (ILC) in designing a torque controller for switched reluctance motors (SRMs). The demanded motor torque is first distributed among the phases using a torque-sharing function. Following that, the phase torque references are converted to phase current references by a torque-to-current converter and the inner current control loop tracks the phase current references. SRM torque is a highly nonlinear and coupled function of rotor position and phase current. Hence, the phase current references for a given demanded torque can not be obtained analytically. Assumption of linear magnetization characteristics results in an invertible torque function. However, the nominal phase current references obtained using this torque function will lead to some torque error as motor enters into magnetic saturation. For a constant demanded torque, the error in the phase current references will be periodic with rotor position. Hence, we propose to use ILC to add a compensation current to the nominal phase current references so that torque error is eliminated. Similarly, current tracking for the nonlinear and time-varying system is achieved by combining a simple P-type feedback controller with an ILC controller. The proposed scheme uses ILC to augment conventional feedback techniques and hence, has better dynamic performance than a scheme using only ILC. Experimental results of the proposed scheme for an 8/6 pole, 1-hp SRM show very good average as well as instantaneous torque control.     

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。     

4相8/6开关磁阻电机建模与仿真

由于开关磁阻电机的双凸极结构特点和开关性供电特点,使其难以简单地用传统电机的分析方法解析计算。在开关磁阻电机数学模型基础上,借助离线堵转实验得到的数据,分析得到了SRM的电感模型,并对该模型进行傅里叶分析,建立基于MATLAB/SIMULINK的开关磁阻电机非线性动态模型。仿真与实验结果证实模型的正确性、控制策略的有效性和系统运行可靠,为将来开关磁阻电机调速系统的优化改进提供了参照。     

开关磁阻电机的实时仿真平台研究

文中主要介绍了开关磁阻的实时仿真平台。基于PC机直接控制开关磁阻电机的运行的目的,采用Matlab中的实时代码生成工具箱将Simulink中的程序编译成C程序,由PC机发出信号,经PCI数据采集卡被传送至驱动电路,驱动电路再提供一个12 V的驱动电压的方法控制电机运行。实验结果显示PC机控制电机运行正常,仿真波形图显示A、B、C三相脉冲间隔相等,分别在0°、30°、60°时开通,每次开通角为10°符合设定值。本仿真平台达到实时控制电机的要求。     

基于虚拟仪器的开关磁阻电机监控系统

为了提高开关磁阻电机控制系统的实用性和可靠性,利用NI虚拟仪器构建了监控系统,可以实时监测和调整电机运行时的重要参数。该方案以装有数据采集卡的PC机和DSP作为硬件基础,利用LabVIEW软件将各类传感器传送的信号进行实时处理,同时记录和显示各项数据,然后再利用相应的算法完成对数据的分析。DSP则作为PC机故障时的备用系统。实验证明,该控制系统的实用性和可靠性比之前大大提高。     

Bifurcation and chaos analysis of power converter for switched reluctance motor drive

Bifurcation and chaos characteristics of single phase power converter in switched reluctance motor (SRM) drive system are studied by establishing its corresponding discrete iterative map model in this article. The discrete iterative map model of the converter is first derived. The stability theoretical analysis shows that the system may lose stability as the variation of system parameters in periodic-1 operation. With the bifurcation diagrams and Lyapunov exponents’ analyses, the operation state regions of current-controlled single phase of SRM drive can shift among stable periodic-1 region, chaos region and multi-periodic region. To verify the theoretical analysis results, time-domain waveforms and power spectra of current-controlled single phase of SRM drive are obtained by Runge–Kutta algorithm. Moreover, theoretical analysis and simulation results are verified by experimental circuit.     

High-precision position control of a novel planar switched reluctance motor

This paper presents the position control of a novel two-dimensional (2-D) switched reluctance (SR) planar motor. The planar motor consists of a six-coil moving platform and a flat stator base made from laminated mild steel blocks. Unlike conventional x-y tables, which stack two moving slides on top of each other, the proposed 2-D planar motor has the advantages of simple mechanical construction, high reliability, and the ability to withstand harsh operating conditions. Together with the two linear encoders attached to the x-axis and y-axis, the motor can be controlled under closed-loop mode. To combat the problem of force nonlinearity, this paper proposes a cascade controller with force linearization technique to implement the drive controller. Due to the unique structure of the planar motor's magnetic circuit, there is very little coupling between the x-axis and y-axis, and no decoupling compensation is needed. Preliminary results show that the proposed SR planar motor has a positional accuracy of 5 /spl mu/m and a maximum acceleration/deceleration rate of 2 G.     

Fuzzy logic torque ripple reduction by turn-off angle compensationfor switched reluctance motors

A fuzzy-logic-based turn-off angle compensator for torque ripple reduction in a switched reluctance motor is proposed. The turn-off angle, as a complex function of motor speed and current, is automatically changed for a wide motor speed range to reduce torque ripple. Experimental results are presented that show ripple reduction when the turn-off angle compensator is used     

Novel rotor position estimation technique for switched reluctance motor (SRM)

This article presents a new and novel method which is designed to detect the rotor position at standstill and at low speeds in switched reluctance motor. Since the inductance parameter plays a significant role both in the steady state and in the dynamic characteristics of an electromagnetic device, the rotor position can be determined using inductance bridge systems to measure unknown inductance and resistance values. In this method we use motor winding in Maxwell–Wien Bridge, with the standard capacitor and the resistor in parallel with it adjusted to achieve balance in an aligned position when the maximum inductance occurs. The supply voltage, in conjunction with the drive transistor, produces short pulses for this AC bridge. The condition of the balanced bridge v ₀?=?0 leads to the relation between the impedances of the bridge branches. The phase inductance varies with the rotor position. Therefore the motor goes into an unaligned position and the Maxwell–Wien Bridge goes into an unbalanced condition thus causing variation in the state of the bridge output. It then continues to sense the rotor position with the motor running by applying the same procedure, but only to the un-energised phases winding. The simulation and experimentally obtained results demonstrate the feasibility and practicability of this method.