矿井提升机直接转矩控制系统转矩脉动最优控制

针对矿井提升机直接转矩控制系统低速段运行时存在转矩脉动过大的问题,提出了一种矿井提升机转矩脉动最优控制方法。该方法以预测模型为基础,采用零电压矢量注入方式进行最优电压矢量的占空比调整。整个占空比计算过程以转矩脉动最小为设计指标,采用在线计算的方式实时获得最优占空比。实验结果表明,该方法在低速时可有效减小电动机转矩脉动,获得优异的转矩控制性能。     

矿井提升机直接转矩控制系统转矩脉动最优控制

针对矿井提升机直接转矩控制系统低速段运行时存在转矩脉动过大的问题,提出了一种矿井提升机转矩脉动最优控制方法。该方法以预测模型为基础,采用零电压矢量注入方式进行最优电压矢量的占空比调整。整个占空比计算过程以转矩脉动最小为设计指标,采用在线计算的方式实时获得最优占空比。实验结果表明,该方法在低速时可有效减小电动机转矩脉动,获得优异的转矩控制性能。     

洁净机器人反应转矩观测与碰撞保护研究

提出一种基于反应转矩观测器的机器人碰撞保护方法;机器人的反应转矩由基于模型的干扰观测器估值得到,模型的建立包括电机系统转矩模型与机器人系统动力学模型两部分;由于洁净机器人特殊的构型及关节耦合关系,机器人的动力学建模被大大简化,同时对简化后的模型采用最小二乘法对惯性参数和摩擦参数进行辨识,提高了模型的精度;根据永磁同步电机的转矩模型与机器人动力学模型,可以得到基于电机电流的机器人关节转矩;机器人与外界环境接触时,关节转矩的增加量即为反应转矩;通过设计反应转矩观测器并采用力/位混合控制结构,实现基于电流的机器人主动柔顺控制功能,并在洁净机器人进行碰撞保护实验,实际运行结果验证了该方法的有效性。     

离散变频软起动技术的研究

三相感应电动机离散变频软起动在限制大的起动电流的同时,能够保证足够大的起动转矩,非常适用于重载起动的设备.本文提出了采用对称分量变换相量夹角最小的相量图方法快速确定最佳相位角组合的方法。在理论的基础上,利用SIMULINK建立了离散变频高转矩软起动器的仿真。结果表明,离散变频软起动器能使电机以高转矩和较小起动电流平滑起动,验证了这种离散变频高转矩软起动方法的正确性和有效性。     

永磁轮毂电机目标驱动力SVPWM柔性控制

在对永磁轮毂电机进行目标驱动力控制时,采用直接转矩控制会产生很大的转矩脉动,常规的矢量控制因控制器的高频开关信号和定子磁链圆逼近算法造成高频次的电磁转矩脉动.针对上述问题,通过分析矢量控制理论和空间矢量脉宽调制(SVPWM)算法,综合最小二乘法误差优化原理,对矢量控制系统中的SVPWM模块进行改进,设计出一种SVPWM柔性控制器.最后使用MATLAB/Simulink搭建仿真模型,在同一设定工况下,对比了直接转矩控制、常规SVPWM控制、SVPWM柔性控制的仿真效果.结果表明:SVPWM柔性控制技术优于直接转矩控制和常规SVPWM控制,降低了转矩动态变换时的脉动幅度和频次.上述方法提高了永磁轮毂电机的控制精度,具有良好的动态性能.     

桥门式起重机最优调压节能仿真研究

为了实现起重机最优调压节能运行,针对起重机的恒转矩运行和变工况负载特性,基于异步电动机Γ型等效电路,将定子铜耗和铁耗看作是仅与定子电压有关的不变损耗,将转子铜耗看作是随负载转矩变化的可变损耗,得到电气总损耗与定子电压和负载转矩的直接关系。通过求解得出电动机稳定运行条件下使电气总损耗最小的最优电压。研究和仿真结果表明:定子电压和负载转矩共同影响总损耗,按照电动机稳定运行时的近似转差率得出总损耗的精确解和近似解在低于200V时,误差较大,在高于200V时误差几乎为零,而随负载转矩变化的最优电压误差不超过7V;起重机按照负载转矩变化的适时调压运行方式的节能效果是显著的。     

基于BP神经网络的VVP水动力系数预报

将BP神经网络应用于全方位推进器周期螺距状态推力系数和转矩系数预报.针对BP神经网络在训练中存在的学习速度慢、易于陷入局部最小等缺点,采用变学习率的BP算法加以改进.对全方位推进器周期螺距状态推力系数和转矩系数进行预报,结果表明,预报值的精度明显高于由近似公式计算所得的值,采用BP神经网络对全方位推进器周期螺距状态的推...     

基于转矩电流的立井施工提升系统载荷测量方法

目前矿山提升系统载荷测量方式主要是通过在井底加装称重传感器测量载荷,但该方法无法应用于立井施工提升系统。通过分析钢丝绳张力与载荷的函数关系来测量提升载荷的方法实现了载荷的动态测量,但传感器的安装和钢丝绳自身塑变导致的测量精度问题一直难以解决,带来安全隐患。为解决上述问题,针对提升系统的电气传动系统为异步电动机交-交变频传动矢量控制的情况,根据变频器可直接输出转矩电流这一特性,提出了一种以转矩电流为测量信号的提升载荷测量方法。通过建立提升系统数学模型和动力学分析,确定了转矩电流与提升载荷的相关性;在此基础上引入粒子群优化最小二乘支持向量机,建立转矩电流与提升载荷在加速、匀速和减速3个运行阶段的关系模型;在各运行阶段给载荷施加不同的扰动,通过Matlab仿真分析提升载荷与转矩电流的关系。仿真结果表明,提升载荷与转矩电流在各运行阶段都存在对应关系,通过转矩电流可以精确地还原出提升载荷及其波动情况。     

油电混合动力汽车不同工况最小油耗控制仿真

油电混合动力汽车中燃油和电池电能量的使用是影响最小油耗的主要因素.传统控制油电混合动力汽车油耗方法存在设置的SOC门限值不合理问题,导致发动机输出转矩仿真控制效果不佳,因此提出全新的油电混合动力汽车不同工况最小油耗控制仿真.研究采用均值分类法处理基本数据,并将处理数据与汽车行驶工况进行合成;以最小油耗为目标,设置以油耗控制最优问题为核心的SOC门限值;根据发动机输出功率和APU输出功率之间的关系,设计最小油耗仿真控制模型.此次测试共设置5组不同程度的工况,根据测试结果可知:提出的最小油耗控制仿真,对于发动机输出转矩仿真控制,有更好的油耗控制效果,与两种传统方法相比,上述方法在仿真控制下,可以回收的能量比传统方法多出近30％,可见上述方法更加适合控制油电混合动力汽车在不同工况中的油耗.     

基于CPG的上肢周期性运动控制的研究

依据Ken等人所提供的曲柄转动机构中人体手臂运动的实验及其力学模型,根据互抑制神经振荡器原理和EMG信号的特点,构造了上肢屈肌和伸肌的中枢模式发生器（CPG）模型,由CPG的输出建立上肢运动的六肌模型,并得到所需要的驱动转矩.根据上肢运动的最小转矩原理,通过遗传算法优化CPG的参数.仿真结果表明：基于CPG模型基础上的上肢动力学模型所得到的计算结果与实验数据有很好的一致性.     

Development of a new spindle motor for a hard disk drive

A new spindle motor is developed with a sloped permanent magnet (PM) for a hard disk drive (HDD). In a conventional spindle motor, a pulling plate is installed at the stationary part under the rotating PM to pull down rotating bodies. This axial force is required for stable operation of the spindle motor using a hydrodynamic bearing. However, the pulling plate has considerable iron loss and a negative torque opposing the direction of rotation due to the induced eddy currents. Our proposed model has a sloped PM surface to generate the required axial force as well as torque without the pulling plate. Optimal design is carried out by a response surface methodology, and the new spindle motors are prototyped. The resulting electrical and mechanical performance of the prototyped motors is compared with that of conventional models, showing the possibility of adapting the proposed model for an HDD spindle motor.     

Adaptive steering‐based HDTC algorithm for PMSM

This paper introduces sensorless hysteresis direct torque control for permanent magnet synchronous motors to provide a reduced torque pulsation profile, which leads to a smaller mechanical vibration. The suggested algorithm utilizes the principle of vehicle steering, which continuously fixes the direction of the vehicle in the track. Moreover, the algorithm efficiently employs the output of torque and the output of flux error controllers used in basic hysteresis direct torque control to select two nonzero adjacent vectors. The initial switching time for the selected vectors is determined by a function that considers the absolute magnitude of the torque error and the magnitude of the flux error in addition to the space angle position of the stator flux. To reduce the processing time in the control signal flow, a suggested structure for switching the initial time of the selected vectors is developed. The final switching time of the vectors is adaptively adjusted according to the minimum required stator voltage to drive the load and according to the stored rotor energy that arises due to the inertia of the mechanical load connected to the motor shaft. The simulation results along with the experimental results show a fast dynamic response of torque, relatively reduced torque ripples, and reduced current harmonics compared to the basic hysteresis direct torque control.     

Piezoelectric micromotors for microrobots

The authors have begun research into piezoelectric ultrasonic motors using ferroelectric thin films. The authors have fabricated the stator components of these millimeter diameter motors on silicon wafers. Ultrasonic motors consist of two pieces: a stator and a rotor. The stator includes a piezoelectric film in which bending is induced in the form of a traveling wave. A small glass lens placed upon the stator becomes the spinning rotor. Piezoelectric micromotors overcome the problems currently associated with electrostatic micromotors such as low torque, friction, and the need for high voltage excitation. More importantly, they may offer a much simpler mechanism for coupling power out. Using thin films of lead zirconate titanate on silicon nitride membranes, various types of actuator structures can be fabricated. By combined new robot control systems with piezoelectric motors and micromechanics, the authors propose creating micromechanical systems that are small, cheap and completely autonomous     

Unbalanced magnetic force and cogging torque of PM motors due to the interaction between PM magnetization and stator eccentricity

We investigate the characteristics of cogging torque and unbalanced magnetic forces (UMF) due to the interaction between magnetization of permanent magnets (PM) and stator eccentricity in PM motors. We mathematically and numerically show that the third harmonic of PM magnetization with stator eccentricity decreases the amplitude of the pole harmonic of the cogging torque and UMF while at the same time increasing the amplitude of the least common multiple harmonic of the pole and slot numbers of cogging torque and UMF in PM motors. The effects of the third harmonic of PM magnetization in the PM motors with stator eccentricity were experimentally verified by measuring UMF and acoustic noise.     

Reduction of torque ripple and mechanical vibration of spindle motors in hard-disk drives using a sinusoidal driver

Mechanical vibration and acoustic noise are major obstacles in the development of high-density and high-spindle-speed hard disk drives. Torque ripple caused by the electrical driver is the main source of vibration and noise. This paper proposes a novel driver for spindle motors in hard disk drives based on the principle of position sensorless vector control. To reduce torque ripple, the proposed driver feeds the spindle motor in sinusoidal driving mode by which the sinusoidal current of the motor can be obtained. Experimental results of the proposed driver demonstrate the better driving performance in startup condition and fine sinusoidal current in steady state. Vibration testing shows significant improvement in the attenuation of vibration: the dominant vibration modes can be reduced to one tenth compared to that of a conventional driver. In addition, the mechanism of inducing torque ripple from time-harmonic currents is analyzed and the relationship between induced torque ripple and exhibited vibration modes is examined.     

Design of a torque controller for the adept-2 robot

The ability to command actuator torque is necessary to perform research into robot control. Commercial manipulators using direct-drive actuators offer high performance, but do not allow specification of actuator torque. We experimentally characterize the motors in an Adept-2 manipulator, and develop a linearizing and decoupling controller which allows torque specification. Torque ripple is 13%.     

Feedback linearizing and sliding mode control of a variable reluctance motor

Direct-drive connection of electric motors represents a suitable solution to friction and backlash problems introduced by mechanical reduction gears. Variable reluctance (VR) are a special type of switched reluctance motors whose construction is well suited for direct-drive connection. Although these motors are traditionally conceived as stepper motors, continuous motion can be obtained by implementing suitable closed-loop control in the drive. The authors' main aim is to design a high-performance robust controller for a VR motor intended for velocity trajectory tracking in robotics applications where continuous motion is required. A cascade controller structure (velocity-torque) is considered. In the design of the torque controller, both feedback linearizing and sliding mode techniques are considered. Feedback linearization performs slightly better in the ideal case, but under more realistic operating conditions the sliding mode controller demonstrates comparable or even better performance. A very simple but extremely robust velocity controller is designed using a dynamic sliding mode approach, ensuring robustness to large variations of load torque and inertia, typical of direct-drive robotics applications. A simulation experiment of the overall controller with the motor connected to a single link robotic arm shows very good tracking properties as well as insensitivity to large variations of load torque and inertia.     

Torque distribution using a weighted pseudoinverse in a redundantly actuated mechanism

When mobility, the number of independent variables to describe system motion exactly, is greater than the degree-of-freedom of task space, the system is called a kinematically redundant system. On the other hand, redundant actuation indicates a situation when there are more actuators than a system's mobility. Redundant actuation yields many advantages. First, actuation redundancy can increase the force, velocity and acceleration of an end-effector. Second, if some actuators are out of order, the system can still work well. This fault-tolerant capability is useful for remote control robots in space or nuclear plants. Impulsive force can decrease when modulating arbitrary stiffness without feedback control. The performance of a system can be improved by optimizing redundancy. However, there are some issues of economic efficiency and minimization of a system, because redundant actuation may involve more actuators than non-redundant actuation. In addition, there are infinite torque sets of motors for the same task. We used a weighted pseudoinverse matrix for torque distribution. To reduce the maximum torque, we suggested the use of the minimum norm torque as the weighting values. This method allows for smaller motor capacity, and can contribute to economic efficiency and minimization of a system.     

Reduction of torque ripple and mechanical vibration of spindle motors in hard-disk drives using a sinusoidal driver

Mechanical vibration and acoustic noise are major obstacles in the development of high-density and high-spindle-speed hard disk drives. Torque ripple caused by the electrical driver is the main source of vibration and noise. This paper proposes a novel driver for spindle motors in hard disk drives based on the principle of position sensorless vector control. To reduce torque ripple, the proposed driver feeds the spindle motor in sinusoidal driving mode by which the sinusoidal current of the motor can be obtained. Experimental results of the proposed driver demonstrate the better driving performance in startup condition and fine sinusoidal current in steady state. Vibration testing shows significant improvement in the attenuation of vibration: the dominant vibration modes can be reduced to one tenth compared to that of a conventional driver. In addition, the mechanism of inducing torque ripple from time-harmonic currents is analyzed and the relationship between induced torque ripple and exhibited vibration modes is examined.

     

基于终端滑模控制的电动汽车转向稳定性研究

针对电动汽车转向时的稳定性问题,以双轮毂电机电动汽车为研究对象,利用线性二自由度车辆模型得到理想参数,提出了基于横摆角速度的终端滑模横摆力矩控制。同时利用Simulink搭建了整车七自由度的车辆模型,通过低速和高速两种情况来进行算法验证。仿真结果表明,上述算法相对于垂直载荷力矩控制和传统滑模控制而言,能够有效的减少目标参数趋于稳定的时间,抗干扰能力强。力矩分配之后输出力矩作用于轮毂电机,便可以有效的保证车辆运行转向时的安全性和稳定性。