已阅读5页,还剩27页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
1,Chapter 9,Kouhei Ohnishi, Nobuyuki Matsui, Yoichi Hori,Estimation, Identification, and Sensorless Control in AC Drives,2,AC drives became more and more economical and popular.,Since the early years of the 20th century, electric motors for variable speed drives have been widely applied in large-capacity applications the steel industry the automobile industry In the early stage, DC motors were widely used for adjustable speed control Since the late 1960s, AC motors have been replacing DC motors in a wide area of industry applications Since AC drives required more complicated controllers in the beginning, they were not so economically feasible Allied to advances both in digital control technology and power semiconductor devices, AC drives became more and more economical and popular. In almost all areas, DC drives are now replaceable with AC drives,3,However, there still exist some areas which are not suitable for AC drive applications. One of these is the area which requires precise torque control. For instance, injection machines. AC motors sometimes generate torque error or torque pulsation due to some parameter variations. To overcome such problems, more sophisticated techniques are necessary in the controller. These techniques are based on estimation or identification of motor parameters Employ the recent developments in digital control, including high-speed digital signal processors (DSPs) and parallel processing,To overcome torque problems.,4,9.2 PARAMETER ESTIMATION IN AC DRIVES,9.2.1. Parameter Identification In Brushless Motors 9.2.2. Parameter Identification In Induction Motors,5,The control scheme of brushless motors with trapezoidal flux distributions (BLDM, brushless DC motor) is relatively simple. Usually it does not need parameter identification. For brushless motors with sinusoidal flux distribution (PMSM, permanent magnet synchronous motor), generally identification of the parameters is necessary for precise control . (3 electric parameters) Armature resistance, armature inductance, and EMF coefficient.,Parameters of Brushless Motors,6,Two effective approaches are presented here: self-tuning regulator (STR) which has a tuning ability to make output-error zero inside the controller; model reference adaptive system (MRAS) which has a referred model in the controller. Direct applications of STR and MRAS to parameter identification do not always lead to successful results, because of the limitation of the processing time of the controller CPU. Since identification should be performed in parallel with current and speed control, it is essential to reduce the processing time for identification by a simple algorithm.,7,STR-Based Parameter Identifier,At steady-state, the PMSM has the simple equivalent circuit just like a DC motor. Terminal voltage, line current, and armature resistance are measured to identify the circuit parameters. Figure 9-1 shows an experimental evaluation of the influence of such parameter variations in armature current error at steady state. A current-regulated voltage source inverter supplies almost sinusoidal current. In the figure, the ordinate is the current control error due to the parameter variation,8,the parameter variation coefficient is defined as,9,10,since the estimation of the armature inductance uses division and the relatively small d-axis voltage, the error is a little larger compared to that of the EMF coefficient.,11,MRAS-Based Parameter Identifier,Figure 9-4 displays a MRAS-based identification approach, which includes a voltage-based motor model as a reference model.,The input of the identifier is a current difference between model and actual motor. The current difference is decomposed into two elements, from which the armature inductance and the EMF coefficient are identified.,12,the experimental results of identification of armature inductance and EMF coefficient for a tested motor.,13,the experimental estimation error,14,Application of Parameter Identification to Torque Control,An interesting application example for the parameter identification of the brushless motor is a “torque sensorless“ torque control. Fig(a), the conventional current-based torque control system. The torque reference is divided by a torque constant (=EMF coefficient in SI unit) to generate a current reference.,15,16,Parameters of Induction Motors,Basically induction motor in steady state is represented by the equivalent circuit in Figure 9-7. The classical no-load test, locked rotor test, and electrical quantity measurement test give identified parameters in Figure 9-7.,17,A sample of flowchart is shown in Figure 9-8 4.,18,9.3 Sensorless Drives of AC Motors,19,sensorless drives of AC motors,basically,the vector-controlled AC motors require speed or position sensors these sensors bring several disadvantages drive cost reliability machine size noise immunity it is necessary to achieve the precise control of torque and speed without using position and speed sensors(so-called sensorless drives of AC motors),20,9.3.1 Sensorless Drives of Brushless Motors,As stated, there are two kinds of brushless motors: the motor with a trapezoidal flux distribution and that with a sinusoidal flux distribution. The approaches to sensorless drive of the brushless motor vary, depending on the rotor flux distribution. the motor with a trapezoidal flux distribution The first one provides an attractive candidate, because two of the three stator windings are excited at a time. As a result, the unexcited winding can be used as a sensor 10, 11; that is, the speed EMF induced in the unexcited winding is used to determine the rotor position and speed. the motor with a sinusoidal flux distribution excites three windings at a time and the sensorless control algorithm becomes complicated.,21,Since the actual rotor position is not known without a position sensor, the aim is to make the angular difference between the fictitious and actual rotor positions converge to zero.,the motor with a sinusoidal flux distribution,the d-q axis corresponds to an actual rotor position the - axis is a fictitious rotor position,22,two approaches,Both are the estimation of the angular difference by using the detected state variables and the estimated state variables which are obtained from a motor model in the controller. The approaches differ according to the motor model, i.e. Voltage model-based drive 12 Current model-based drive 13 These two are basically the model-based control and generally require on-line identification of the motor parameters if higher performance is required. However, it is interesting to note that the second method has robust control characteristics against the motor parameter variation.,23,the voltage model-based sensorless drive,the voltage equation is,the voltage equation under the ideal condition that the fictitious and actual axes are coincident is,24,the angular difference can be made to converge to zero by the following rule if vr0 , then decreases if vr 0 , then increases (for clockwise rotation),Taking a difference between -axis voltage assuming is small,25,(whereT is a sampling period and is the motor speed of the model), then,the current model-based sensorless drive,The current model is,the current difference is,26,torque-speed characteristics under a current model-based algorithm.,The motor rating is 1.2 (kW), 6-poles, 1200 (rpm), 98 (kgf cm). The maximum speed is 1500 (rpm), the minimum speed is 60 (rpm), and a steady-state maximum speed error is within 0.4%.,27,9.3.2 Sensorless Drives of Vector Controlled Induction Motors,the basic idea is estimation of speed by using applied voltage, line current, and frequency Slip frequency control approach field orientation control approach,28,Slip frequency control approach,29,field orientation control approach,not only the speed but also the rotor flux are simultaneously estimated for the sensorless drive in a wide speed range. The stator equation is used for correction of adjustable current reference model. The speed is estimated by a kind of error of flux components which is derived from
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 玉米爆花机投资项目可行性分析报告
- 模制抗菌素瓶项目立项申请报告
- 皮带传动实验台投资项目可行性报告
- 中考复习古代文学和新时期的伦理观念
- 中考复习古代文学和当代社会现实问题
- 中考语文复习句型拓展运用
- 白酒总代理协议书
- 抖音文案查重机制
- 2023年多级飘尘采样计投资申请报告
- 原发性高血压健康教育
- 2024年保密知识竞赛考试题库400题(含答案)
- 低压电工理论复习考试题库(附答案)
- 2024年4月自考00054管理学原理试题
- 输电线路运行维护服务投标方案(技术方案)
- MOOC 计算机组成与CPU设计实验-江苏大学 中国大学慕课答案
- 2024届新疆阿克苏地区沙雅县达标名校中考历史押题试卷含解析
- 临时起搏器护理课件
- 2024年天翼云从业者认证考试题库大全(含答案)
- 小学信息科技六年级 单元作业设计 信息技术新视野
- 各种手术备皮范围
- 浙江杭州径山度假区建设管理有限公司招聘考试试题及答案
评论
0/150
提交评论