电机调速控制英文翻译

郑州航空工业管理学院

毕 业 论 文（设 计）外文翻译

姓 名指导教师 王义琴 职称 讲师

二О一 六 年 三 月 十 日

The Design of the Vector Control System of Asynchronous Motor

Abstract: Among various modes of the asynchronous motor speed control, vector control has the advantages of fast response, stability, transmission of high-performance and wide speed range. For the need of the asynchronous motor speed control, the design uses 89C196 as the controller, and introduces the designs of hardware and software in details. The Design is completed effectively, with good performance simple structure and good prospects of development.

Keywords: Asynchronous motor, 89C196, Vector control

1. Introduction

AC asynchronous motor is a higher order, multi-variable, non-linear, and strong coupling object, using the concept of parameters reconstruction and state reconstruction of modern control theory to achieve decoupling between the excitation component of the AC motor stator current and the torque component, and the control process of AC motor is equivalent to the control process of DC motor, the dynamic performance of AC speed regulation system obtaining notable improvement, thus makes DC speed replacing AC speed possible finally. The current governor of the higher production process has been more use of Frequency Control devices with vector-control.

2. Vector Control

With the criterion of producing consistent rotating magneto motive force, the stator

AC currenti A , i B , i C by3S/2S conversion in the three-phase coordinate system, can be equivalent to AC current i d s ，i q s ， in two-phase static coordinate system, through

vector rotation transformation of the re-orientation of the rotor magnetic field,

e Equivalent to a synchronous rotation coordinates of the DC current i d ，i q e . When

observers at core coordinates with the rotation together, AC machine becomes DC machine. Of these, the AC induction motor rotor total flux ψr , it has become the

equivalent of the DC motor flux, windings d e equivalent to the excitation windings

e of DC motor , i d equivalent to the excitation current, windings q e equivalent to false

static windings, i q e equivalent to the armature current proportional to torque. After

the transformation above, AC asynchronous motor has been equivalent to DC motor. As a result, imitating the control method of DC motor, obtaining the control variable of DC motor, through the corresponding coordinates anti-transformation, can control the asynchronous motor. As a result of coordinate transformation of the current (on behalf of magnetic momentum) space vector, thus, this control system achieved through coordinate transformation called the vector control system, referred to VC system. According to this idea, could constitute the vector control system that can control ψr and i q e directly, as shown in Figure 1. In the figure a given and feedback

signal through the controller similar to the controller that DC speed control system

e e has used, producing given signal i qs of the excitation current and given signal i ds of

e e the armature current, after the anti-rotation transform VR -1 obtaining i qs and i ds , ****

**obtains i *

A , i B , i C by 3S/2S conversion. Adding the three signals controlled by current

and frequency signal ω1 obtained by controller to the inverter controlled by current,

can output three-phase frequency conversion current that asynchronous motor needs for speed.

3. The Content and Thought of the Design

This system uses 80C196 as controller, consists of detection unit of stator three-phase current unit of keyboard input, LCD display modules, given unit of simulation speed detection unit of stator three-phase voltage, feedback unit of speed and output unit of control signals. System block diagram shown in Figure 2, the system applies 16 bits MCU 80C196 as control core, with some hardware analog circuits composing the vector control system of asynchronous motor. On the one hand, 80C196 through the A/D module of 80C196, speed gun and the given speed feedback signals has been obtained, obtaining given torque of saturated limiting through speed regulator, to obtain the given torque current; Use a given function generator to obtain given rotor flux, through observation obtaining real flux, through flux regulation obtaining given excitation current of given stator current, then the excitation current and the torque current synthesis through the K/P transformation, obtaining amplitude and phase stator current, after amplitude of stator current compared to the testing current , control the size of stator current through current regulator.; on the other hand, the stator current frequency is calculated by the simultaneous conversion rate for the time constant of the control inverter, regularly with timer, through P1,submitting trigger word to complete the trigger of the inverter.

4. The Design of Hardware and Software

The hardware circuits of the system mainly consists of AC-DC-AC current inverter circuit, SCR trigger inverter circuit, rectifier SCR trigger circuit, the speed given with the gun feedback circuit, current central regulation circuit, protection circuit and other typical circuits. The design of software includes: speed regulator control and flux detection and regulation.

4.1 AC-DC-AC Current Converter Circuit

The main circuit uses AC-DC-AC Current Converter in the system as shown in Figure 3, and main features can be known as follows:

1) Main circuit with simple structure and fewer components. For the four-quadrant operation, when the brake of power happens, the current direction of the main circuit keeps the same, just changing the polarity of the voltage, rectifier working in the state of inverter, inverter working in the state of rectifier. The inverter can be easily entered, regenerative braking, fast dynamic response. The voltage inverter has to connect to a group of inverters in order to regenerative braking, bringing the electric energy back to power grids.

2) Since the middle using a reactor, current limit, is constant current source. Coupled with current Loop conditioning, current limit, so it can tolerate instantaneous load short-circuit, automatic protection, thereby enhancing the protection of over current and operational reliability

3) The current inverter can converter with force and the output current instantaneous value is controlled by current inverter, meeting the vector control requirements of AC

motors. Converter capacitor charging and discharging currents from the DC circuit filter by the suppression reactor, unlike a greater inrush current in voltage inverter, the capacitor’s utilization is of high level.

4) Current inverter and the load motor form a whole, and the energy storage of the motor windings is also involved in the converter, and less dependent on the voltage inverter, so it has a certain load capacity.

4.2 Inverter SCR trigger drive circuit

The Inverter SCR trigger drive circuit as shown in Figure 4. Inverter trigger signal is controlled by P1 of 80C196, slip signal outputting through P1 via PWM regulation in the SCM through the photoelectric isolation to enlarge, to control the trigger of the inverter. The system uses P1.6 as control and uses P1.0~P1.5 to control six SCR inverters separately, so the trigger circuits is composed by six circuits above.

The principles of drive circuit of SCR trigger inverter are as follows: when the PWM from P1 is high signal after and gate, photoelectric isolation is not on, composite pipe in a state of on-saturated, the left side of the transformer forming circuit, and that the power of the signal amplifies (current enlarges); when the PWM from P1 is low signal after and gate, photoelectric isolation is on, composite pipe in a state of cut-off, and the left side of the transformer can not form circuit; thus, composite pipe equivalent to a switch, and its frequency relied on the frequency of the PWM, so the left side of the transformer form AC signals, to trigger SCR inverter after transformer decompression, half-wave rectifier and filter.

4.3 Current Loop conditioning circuits

After the vector calculation, outputting given current through D/A module, testing feedback current by the current testing circuit, sending them to the simulator of the P1 regulator to regulate, can eliminate static difference and improve the speed of regulation. The output of the analog devices can be regarded as the phase-shifting control signals of the rectifier trigger. Current Loop conditioning circuits as shown in figure 5.

4.4 The control of speed regulator

Speed regulator uses dual-mode control. Setting a value T N of speed error, when the system is more than the deviation (more than 10 percent of the rated frequency), as rough location of the start, using on-off control, at this time, speed regulator is in the state of amplitude limit, equivalent to speed loop being open-loop, so the current loop is in the state of the most constant current regulation. Thus, it can play the overload ability of motor fully and make the process of regulation fastest possibly. When the system enters into a state of small deviation, the system uses PI linear control instead of on-off control. As result, absorbing the benefits of non-linear and linear, the system meets stability and accuracy. The speed regulator flowchart is as shown in figure 6.

4.5 Flux Regulation

Slip frequency vector control system can be affected by the motor parameters, so that the actual flux and the given flux appear a deviation. This system is of observation and feedback in the amplitude of the magnetic flux, regulating flux of the rotor,

actual flux with the changes of given flux.

Flux regulator is also the same as the speed regulator, using PI regulator. The discrete formula is:

i m (n ) =i m (n -1) +k m {∆e i (n ) +T S e i (n )}/t n （1）

Plus a reminder to forecast for correction:

I m =2i m (n ) -i m (n -1) （2） In the formula, k m is proportional coefficient, t n is integral coefficient, T s is sampling period, I m is the actual output value.

∆e n =e (n ) -e (n -1) （3）

e n =Φ*

2(n ) -Φ2(n ) （4）

When it is in the state of low frequency (f

Through the Approximate rotor flux observer and the formula Φ2=I m 1L m =(V 1-I T r 1) /ω0-I m 1L 1 to observe the flux amplitude, only open-loop

control of flux, that is, to calculate from a given flux, and that is I m =Φ*

2/L m .In

addition, in order to avoid disorders, or too weak and too strong magnetic, limiting the output i m in preparation for the software, making it in the ranges from 75% to

115% rated value.

5. Design Summary

This text researches the vector control variable speed control system of the asynchronous motor design. The SCM 80C196 and the external hardware complete the asynchronous motor speed vector control system design efficiently, and meet the

timing control requirements. The vector control system design thinks clearly, has a good speed performance and simple structure. It has a wide range of use and a good prospect of development from the analysis and design of the speed asynchronous motor vector control systems.

The innovations:

(1) Complete the data acquisition of the speed and voltage, output the control signal and save the devices effectively with the help of the 80C196 microcontroller owned A/D, D/A.

(2) Because the Current Source Inverter uses forced converter, the maximum operating frequency is free from the power grid frequency. And it is with wide speed range.

(3) This system uses constant flux to keep the constant flux stably. Use stator physical voltage amplitude to approximate the observed flux amplitude value. The magnetic flux overcomes the impact of the parameters changes. This way is simple

and effective.

Figure 1. Vector Control System Principle

Figure 2. Scheme of System

Figure 3. AC-DC-AC Current inverter Circuit

Figure 4. Inverter SCR trigger drive circuit

Figure 5. Current Loop conditioning circuits

Figure 6. Flux regulation flowchart

References

Li, Da, Yang, Qingdong, and Liu, Quan.(2007). The DSP permanent magnet synchronous linear motor vector control system. Micro-computer information, 09-2:195-196

Liu, Wei. (2007). The application design about vector control of current loop control. Micro-computer information, 07-1: 68-70

Zhao, Tao, Jiang, WeiDong, Chen, Quan, and Ren, Tao. (2006). The research about the permanent magnet motor drive system bases on the dual-mode control. Power electronics technology, 40 (5) :32-34

异步电动机矢量控制调速系统设计

摘 要:异步电动机的各种调速方式中，矢量控制的调速方式响应快、稳定性好、传动性能高、调速范围宽。针对异步电动机的调速需要，设计以80C196为控制器的矢量控制调速系统，并详细介绍了系统的硬件设计和软件设计。该系统有效地完成了异步电动机矢量控制调速系统设计，调速性能好、结构简单，具有很好的发展前景。

关键词：异步电动机，89C196，矢量控制

1. 引言

交流异步电动机是一个高阶、多变量、非线性、强藕合的被控对象，采用参数重构和状态重构的现代控制理论概念可以实现交流电动机定子电流的励磁分量和转矩分量之间的解藕，实现了将交流电动机的控制过程等效为直流电动机的控制过程，使交流调速系统的动态性能得到显著的改善和提高，从而使交流调速最终取代直流调速成为可能。目前对调速特性要求较高的生产工艺已较多地采用矢量控制型变频调速装置。

2. 矢量控制

以产生完全一致的旋转磁动势为准则，在三相坐标系下的定子交流电流i A , i B , i C 通过3S ／2S 变换，可以等效成两相静止坐标系下的交流电流i d s ，i q s ，再通过按

e i q 转子磁场定向的矢量旋转变换，可以等效成同步旋转坐标系下的直流电流i d ，。e

当观察者站在铁心上与坐标系一起旋转时，交流机就变成了直流机。其中，交流异步电动机的转子总磁通 r ，就变成了等效的直流电动机的磁通，d e 绕组相

e 当于直流电机的励磁绕组，i d 相当于励磁电流。q e 绕组相当于伪静止绕组，i q e 相

当于与转矩成正比的电枢电流。异步电动机经过如上的变换后就等效成了直流电动机。因而，可以模仿直流电机的控制方法，求得直流电机的控制量，再经过相应的坐标反变换，就能够控制异步电动机了。由于进行坐标变换的是电流(代表磁动势) 的空间矢量，所以，这样通过坐标变换实现的控制系统就叫作矢量控制系统，简称VC 系统。按照这种设想，可以构成直接控制ψr 和i q e 的矢量控

制系统，如图1所示。图中给定和反馈信号经过类似于直流凋速系统所用的控

e e 制器，产生励磁电流的给定信号i qs 和电枢电流的给定信号i ds ，经过反旋转变换

e e **VR -1 得到i qs 和i ds ，再经过2S ／3S 变换得到i *

A 、i B 、i C 。把这三个电流控制信号****

和由控制器得到的频率信号ω1加到电流控制的变频器上，即可输出异步电动机

调速所需的三相变频电流。

3. 设计内容及设计思想

本系统以单片机8OC196为控制器，由定子三相电流检测单元、键盘输入单元、LCD 显示单元、模拟转速给定单元、定子三相电压检测单元、转速反馈单元、控制信号输出单元等部分组成。如图2所示，系统是以16位单片机80C196为控制核心，由一些硬件模拟电路组成异步电动机的矢量控制变频凋速系统。一方面，通过8OC196的A ／D 模块获得转速给定及测速反馈的速度信号，经过速度调节器获得饱和限幅的转矩给定，从而获得给定的转矩电流；利用函数发生器获得给定转子磁通，经磁通观测获得实际转子磁通，再经磁通调节获得定子电流给定励磁分量电流，然后经过K ／P 变换将给定的励磁电流和转矩电流合成，得到定子电流的幅值和相位，定子电流的幅值与电流互感器的检测电流相比较后通过电流调节器去控制定子电流的大小；另一方面，定子电流的频率是把计

算得到的同步速度转换为控制逆变器的时间常数，用定时器定时，通过单片机上的P1口，送出触发字来完成逆变器的触发。

4. 硬件电路及软件设计

本系统硬件电路主要由交一直一交电流型变频器电路、逆变晶闸管触发电路、整流晶闸管触发电路、速度给定与测速反馈电路、电流环调节电路、保护电路等典型电路组成；软件设计主要包括：速度调节器控制和磁通检测与调节两部分。

4．1交一直一交电流型变频器电路

系统的主回路采用图3所示的交一直一交变频器，由图可知它具有以下主要特点：

1) 主回路结构简单，使用的元器件少。便于四象限运行，当再生发电制动时，主回路电流方向不变，只改变电压极性，整流器工作于逆变状态，逆变器工作于整流状态。可方便的进入逆变，进行再生制动，动态响应快。而电压型变频器必须另接一组逆变器才能进行再生制动，把电能回馈给电网。

2) 由于中间采用的是电抗器，故具有限流作用，是恒流源。再加上本系统设有电流环调节、限流，所以可耐受负载瞬时短路，自动进行保护，从而提高了过流保护和运行可靠性。

3) 此电流型逆变器带强迫换流，电流型逆变器所控制的是输出电流瞬时值，符合交流电动机矢量控制的要求。换流电容器的充放电电流由直流回路的滤波电抗器所抑制，不像电压型逆变器中有较大的浪涌电流，故换流电容器的利用率较高。

4) 电流型逆变器与负载电动机形成一个整体，电动机绕组的储能也参与换流，故其换流能力依赖于负载电流，而较少依赖于逆变器电压，因此有一定的负载能力。

4.2逆变晶闸管触发驱动电路

逆变晶闸管触发驱动电路如图4所示。逆变触发信号由单片机8OC196的P1口控制，转差信号在单片机内经PWM 调节后由P1 I：I 输出，经光电隔离器隔离放大，去控制逆变晶闸管的触发端。本系统用P1．6作为控制端，用P1．O-P1．5作为另一端分别控制6个逆变晶闸管，故逆变晶闸管触发电路由6个如图4所示的电路组成。逆变晶闸管触发驱动电路原理如下： 由P1口输出的PWM 经与门后是高电平信号时，光电隔离管不导通，复合管处于饱和导通状态，变压器左边形成回路，并且此信号经复合管功率放大(电流放大) ；当从P1口输出的PWM 经与门后为低电平时，光电隔离管导通，复合管基极电流几乎为零，复合管处于截止状态，变压器左边就不会形成回路；这样，复合管就相当于一个电子开关，这个开关的通断频率由PWM 的频率决定，从而使变压器左边形成交流信号，经变压器降压、半波整流、滤波后去触发逆变晶闸管。

4．3 电流环调节电路

由8OC196经过矢量计算，再由它的D ／A 模块输出电流给定，由电流检测电路检测到反馈电流，同时把他们送人到模拟器件的Pl 调节器中进行调节，以消除静差并能提高调节速度。模拟器件的输出作为整流触发的移相控制信号。电流环调节电路如5图所示。

4．4 速度调节器控制

速度调节器采用双模控制。设定一个速度误差值NT ，当系统大于此偏差状态下(大于1O ％ 的额定频率) ，作为开始段粗定位，采用开关式的砰一砰控制，这时，转速调节器处于限幅状态，相当于转速环开环，使电流环处于最大恒值电流调节。因而，能够充分发挥电机的过载能力，使系统调节过程尽可能最快。当系统偏差已经进入很小的范围时，使系统由开关式的砰一砰控制，转换成PI 线性控制。这样，集中了非线性和线性控制的优点，使系统即满足稳定性又满足精确性。速度调节器功能流程图如图6所示。

4．5 磁通调节

采用转差型的矢量控制系统易受电机参数变化的影响，使实际磁通与给定磁通发生偏差。故本系统中对磁通幅值进行了观测和反馈，对转子的磁通进行调节，使实际磁通跟随给定磁通变化。磁通调节器也象速度调节器一样，使用PI 调节器。它的离散化公式为：

i m (n ) =i m (n -1) +k m {∆e i (n ) +T S e i (n )}/t n (1) 外加一个外催器进行预报校正：

I m =2i m (n ) -i m (n -1)

(2)

式中为k m 比例系数，t n 为积分系数，T s 为采样周期，I m 为实际输出值。

∆e n =e (n ) -e (n -1)

(3)

e n =Φ*

2(n ) -Φ2(n )

(4)

当在低频时(f

2/L m 。另

外，为了使电机不至于失凋或过分弱磁及强磁，在软件编制中，对i m 输出进行限

幅，使之在额定值75％～115％内。

5. 设计总结

本文研究了异步电动机的矢量榨制变频调速系统的设计，采用了单片机80C196和外围硬件电路有效地完成了异步电动机矢量控制调速系统设汁，达到了适时地控制要求。从对异步电动机矢量控制凋速系统的分析和设计来看，矢量控制系统设汁思路清晰、调速性能好、结构简单，具有很广的用途和很好的发展前景。

本文作者的的创新点：

1) 利用80C196单片机本身的A ／D 、D ／A 分别完成转速和电压数据采集及对控制信号的输出，有效地节省了元器件的使用。

2) 电流型逆变器采用强迫换流，最高工作频率不受电网工频限制，调速范围宽。

3) 系统的控制思想是采用恒磁通控制。以保持磁通的恒定，设计中采用定子物理量电压幅值来近似的观测磁通幅值，以克服参数变化对磁通的影响。此方法实施简便有效。

图1 矢量控制系统原理结构图

图2 系统框图

图3 交一直一交电流型变频器电路

图4 逆变晶闸管触发驱动电路

图5 电流环调节电路

图6 磁通调节流程图

参考文献

[1]李大，杨庆东，刘泉基于DSP 交流永磁同步直线电机矢量控制系统[J]．微计算机信息，2007(09—2) ：195—196

[2]刘伟关于矢量控制电流环复合控制的应用设计[J]微计算机信息，2007(07—

1) ：68—70

[3]赵涛，姜卫东，陈权，等．基于双模控制的永磁直流电机驱动系统的研究[J].电力电子技术，2006，40(5)：32—34

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