A nonlinear speed observer for permanent-magnet synchronous motors

The application of vector control techniques in AC motor drives demands accurate position and velocity feedback information for the current control and servo control loops. The authors describe a speed observer system suitable for use with permanent magnet synchronous motors as a software transducer. The observer is developed from the dq model of the machine. Design considerations for the observer are discussed. The nonlinearities in the machine model present a problem to the observer design, so a state detection technique is used to achieve global stability and consistent convergence of the observer system. The simulations show that the performance of the observer is robust against noise and parameter uncertainties     

Novel switching techniques for reducing the speed ripple of AC drives with direct torque control

The main theme of this paper is to present novel switching techniques, which insert zero-voltage vectors and/or more nonzero-voltage vectors to the conventional switching table, for AC drives with direct torque control. For the same sampling frequency of a drive controller, the proposed techniques are quite effective in reducing the torque pulsation and the speed ripples of the motors, as demonstrated in several experimental results. Moreover, the experimental confirmations have been made not only on an induction machine but also on a permanent-magnet synchronous machine.     

High efficiency control of synchronous reluctance motors using extended Kalman filter

High-efficiency control of synchronous reluctance motors (SynRMs) is very important in the sense of energy saving and conservation of the natural environment because the efficiency of the SynRM is generally lower than that of other types of AC motors. This paper presents a high-efficiency control strategy for the SynRMs. In this strategy, the d- and q-axes currents are controlled instantaneously. Since the control performance mainly depends on the accuracy of the machine parameters, online parameter estimation using the extended Kalman filter is incorporated into the control strategy. This control strategy improved the drive efficiency and robust performance against machine parameter variations. The validity of the proposed scheme is demonstrated through experimental results.     

汇川技术HD93高压变频器大功率同步电机的应用

在冶金行业中,烧结主抽风机往往采用大功率同步电机来驱动。同步机启动方式为工频异步降压软起动,通过挡板来调节流量,但这种启动和调节方式存在诸多问题,例如启动电流大、重载下容易产生失步、电能浪费严重等,因此对高压大功率同步电机进行变频改造势在必行。汇川此次针对河北某钢铁主抽风机的现场情况,采用先进的磁链闭环矢量控制技术,对同步电机进行了变频节能改造。改造后,彻底解决了启动电流大、重载失步、维护费用高等问题.每年实现节电费用达320万以上。此次对同步机的成功改造标志着汇川在同步电机应用中的突破。     

Commutation of SR motors

Commutation schemes for most common types of switched reluctance (SR) motors are presented. Commutation can be achieved using two- or three-positions sensors and a simple commutation logic in a similar fashion to brushless electronically commutated motors. The commutation logic can be easily housed on a programmable logic array (PLA) or similar device. Two-quadrant operation, usually with two position sensors with variable phase shift and dwell angles, can be tuned up to achieve optimum efficiency at low cost. Four-quadrant operation with multimode commutation schemes, such as normal, boost, longdwell, and brake, which cover most of the SR drive applications, can be easily implemented with simple logic control and feedback from low-resolution position sensors. The speed range can be increased beyond the limit reachable with pulse-width modulation (PWM). A 100% increase in the speed range can be easily obtained by switching modes     

Unified sensorless vector control of synchronous and induction motors

In this paper, a unified theory for sensorless flux estimation and vector control of induction motors and nonsalient permanent-magnet synchronous motors (PMSMs) is developed. It is shown that an estimator and vector controller for one of the motor types can also be applied to the other, with only minor modifications necessary. Two candidate estimators are considered: a variant of the well-known "voltage model" (VM) and a phase-locked-loop-type speed and position estimator. These are applied to both motor types, and evaluated experimentally. For the nonsalient PMSM, an important result is that synchronization can be guaranteed from any initial rotor position.     

Optimization of a synchronous reluctance machine for a sensorless drive with a wide field-weakening range

For more than one century, electrical machines have been utilized for electrical drives. Nowadays, in most applications the electrical machine is fed by an inverter. Three types of machines are available for such purposes: the asynchronous induction machine, the permanent magnet excited synchronous machine and the synchronous reluctance machine. Reluctance machines represent an alternative to the other types when utilized in high-performance drives with a wide speed range. Due to the rotor saliency, these machines have an inherent suitability for a position-sensorless control. The parameters of a 5 kW machine with a maximum speed of 8000 rpm are evaluated by means of nonlinear finite element analyses. With regard to an application in a high-performance drive with a wide field-weakening range and a position-sensorless control scheme, the characteristics are calculated for the conventional reluctance machine as well as the reluctance machine with additional permanent magnets in the rotor. The comparison of the characteristics of the conventional reluctance machine and the permanent magnet assisted reluctance machine clearly shows the improved performance in terms of electromagnetic torque and power factor due to the interior permanent magnets. Thereby, the suitability for the application in position-sensorless drives due to the high effective saliency is preserved.     

Synchronization at startup and stable rotation reversal of sensorless nonsalient PMSM drives

In this paper, a variant of the well-known "voltage model" is applied to rotor position estimation for sensorless control of nonsalient permanent-magnet synchronous motors (PMSMs). Particular focus is on a low-speed operation. It is shown that a guaranteed synchronization from any initial rotor position and stable reversal of rotation can be accomplished, in both cases under load. Stable rotation reversal is accomplished by making the estimator insensitive to the stator resistance. It is also shown that the closed-loop speed dynamics are similar to those of a sensored drive for speeds above approximately 0.1 per unit, provided that the model stator inductance is underestimated. Experimental results support the theory.     

基于FOC的PMSM速度控制系统的研究

根据磁场定向控制理论以及永磁同步电动机调速控制系统的控制方案建立仿真模型,并对永磁同步电动机的调速过程进行仿真.仿真结果较好地反映了永磁同步电动机的调速运行过程,对进一步开发永磁同步电动机速度控制系统具有重要意义.     

基于神经网络的多电机同步控制

文章通过对多电机同步控制的原理及其特点分析,将神经网络与PID控制相结合,设计一种神经网络PID控制器并用于多电机同步控制中,有效的缓解负载带来的同步误差,实验结果表明,在相同扰动情况下,该方法能更好的使多电机以一定速度同步运行。     

大型同步电机交交变频调速系统对电网的谐波影响分析

针对热连轧机组中同步电动机主传动的交-交变频调速系统,定量分析了同步电机负载经由交交变频器对变压器供电网侧产生的谐波影响.分别对不同的负载参数、变压器原副边电感量和变流装置的进线电抗器参数的情况进行了仿真分析.同时,对大型多组交交变频器移相组合式供电进行了数据移位方式仿真.并且对交-交变频器和交-直-交变频器所产生的谐波干扰进行了对比分析.仿真结果表明调节变压器原副边电感量再结合移相组合式供电的方法可以有效地降低大型同步机负载对供电网侧的谐波干扰,并使得总谐波率在各相中分布趋向均衡.     

Stator-flux-oriented vector control of synchronous reluctance Machines with maximized efficiency

This paper presents a position-sensorless vector torque controller designed to achieve maximum efficiency over a range of power and rotational speed for a synchronous reluctance machine. A model of the synchronous reluctance machine is presented which incorporates both winding and core losses. It is then shown that a stator-flux-oriented control scheme can achieve synchronous operation of the machine without a position sensor at medium and high electrical frequencies. For a given speed and torque, power losses in the machine are shown to be a function of only the stator flux magnitude. As the power losses are a convex function of the stator flux level, the optimal flux value can be found using a one-dimensional optimization algorithm, such as the Method of Sequential Quadratic Interpolations. Optimal flux values for a synchronous reluctance machine are determined using an experimental setup that accurately determines losses in the motor/drive system. Experimental results obtained from the test setup confirm the validity of the controller and the optimization algorithm.     

A self-tuning controller for switched reluctance motors

A self-tuning controller for switched reluctance motors is presented, A torque ripple minimizing controller is implemented with online system identification and adaptation technique. The controller uses a nonlinear model of the machine that is updated online using a recursive identification algorithm. The real-time approach improves the overall robustness of the system. Experimental results are presented to validate the self-tuning algorithm     

台达PLC及变频器在悬挂输送链电机同步控制中的应用

本文介绍了三台电机同步控制的几种方案,重点分析了PLc及变频器在悬挂输送链电机同步控制中的应用。由于使用了位置与速度双闭环控制及触摸屏显示,系统具有安全可靠、功能完善、操作简便等优点,取得了良好的经济效益。     

Torque-ripple minimization with indirect position and speed sensingfor switched reluctance motors

A torque-ripple-minimization controller is realized along with indirect position and speed sensing for switched reluctance motors (SRMs). The position and speed estimations are derived from a sliding-mode observer that requires terminal measurements of only phase voltages and currents. The research shows that position- and speed-sensorless observers can be reliably used for control of an SRM. Experimental results using a four-phase, 8/6 SRM and the TMS320C30 digital signal processor are presented. The results demonstrate position- and speed-sensorless closed-loop operation of a torque-ripple-minimized SRM drive     

基于DSP和光电编码器的永磁同步电机速度检测系统

为获取永磁同步电机转子速度,设计了一种基于DSP控制器正交编码电路和光电编码盘的检测系统。DSP识别光电编码盘上光敏管所产生的两路正交编码脉冲,对捕获的脉冲信号进行加减计数,通过对DSP编写的用户程序读取当前计数值,计算电机转子转速。阐述了TMS320F243芯片正交编码和增量式光电编码盘的工作原理,建立了由永磁同步电机、DSP板、逆变功放板和PC机组成的实验测量装置。实验结果表明,在给定的转速设定值下,能够实现快速和较高精度的速度检测,能够满足一般工程系统对交流调速和伺服控制的性能要求。     

General Atomics Linear Motor Applications: Moving Towards Deployment

This paper discusses a number of unique potential applications of linear synchronous and linear induction motors that have resulted from General Atomics' work on the Navy EMALS project for electromagnetically launching planes, and the Urban Maglev project, which uses a long-stator permanent magnet linear synchronous motor. The paper provides an overview of the linear motor technologies being used in these projects, including some of the technical challenges. Potential applications include the use of maglev technology to move cargo in and out of the ports, all-electric trucks which use the energy provided by the linear motor to charge onboard power, and retrofitting linear motors on existing rails to relieve pollution involved in moving cargo in urban settings.      

Sensorlose Drehzahl- und Lageregelung von Permanentmagnet-Synchronmaschinen auf Basis des INFORM-Verfahrens

This paper deals with the operation of permanent magnet synchronous motors without speed- and position sensors in speed- and position-controlled drive applications. Starting from classical field-oriented control methods, a speed-sensorless drive is presented. The basic idea is to estimate the actual speed and position of the drive by means of the INFORM method (low speed and standstill) and EMF-based models (high speed). Measurements on a position-controlled industrial system verify the high quality of the sensorless system which reduces the hardware costs of the drive and increases the reliability by eliminating mechanical components.     

A nonlinear reduced order observer for permanent magnet synchronousmotors

This paper introduces a nonlinear reduced order observer for speed and rotor position estimation in permanent magnet synchronous motors (PMSMs). The observer is based on a model of the motor represented by stationary two-axes coordinates. The theoretical principles of the proposed observer are discussed. Sufficient conditions for convergence as well as convergence speed are established. The observer is designed and tested by simulation. The results show that the observer gives a good estimation of speed and rotor position. In addition, it has low sensitivity to torque disturbances and perturbations of the mechanical parameters     

Ultrasonic motors

Ultrasonic motors represent an alternative to the conventional electromagnetic motor principle. They comprise a stationary resonator, which is excited to produce mechanical oscillations in the ultrasonic frequency range, and a passive rotor. The oscillating end of the resonator drives the rotor via a friction contact. Two newly-developed operating principles for ultrasonic motors based on rod-shaped resonators will be discussed. A single-mode drive utilizes the longitudinal oscillation of a tapered rod-shaped resonator, resulting in an ultrasonic motor with a single direction of rotation. The bimodal motor uses superimposed longitudinal and flexural oscillations and can easily be electronically driven in both directions. Ultrasonic motors are distinguished by high torques at low speed, a large holding torque when switched off and the absence of a magnetic field.