无刷直流电动机转速控制研究与实现.docx

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1、渤海大学本科毕业论文（设计） 无刷直流电动机转速控制研究与实现Research and Implementation on Speed Control of Brushless DC Motors 学院（系）： 工学院 专 业： 电气工程及其自动化 学 号： WS1603004 学生姓名： RAFIULLAH 入学年度： 2016.03 指导教师 : 巫庆辉 完成日期： 2019年11月20日渤海大学Bohai Universit无刷直流电动机转速控制研究与实现摘 要与其他电机相比，无刷直流电机具有更多的优势。所需的硬件项目是利用闭环控制技术实现无刷直流电机速度控制而设计的。BLDC 电机正被

2、广泛应用于各种应用，例如电动自行车、纺纱、车床和钻孔等。该系统可实现精确有效的速度控制。该系统是用户友好的，用户可以进入的速度和电机将运行在确切的速度。设计控制器的目的是跟踪速度参考的变化，并在负载变化期间稳定输出速度。通过开发仿真模型验证了所建系统的有效性。 本课题将简要讨论控制BLDC电机速度的开环、闭环和微控制器方法。第 1 章介绍了 BLDC 电机及其应用。第 2 章将介绍我们将用来控制速度的组件。霍尔位置传感器、无刷直流电机、微控制器等均被用作主要部件。第三章讨论了开环和闭环方法。第4章讨论了微控制器方法。 该系统的目的是讨论无刷直流电机及其工作。在本项目中，我们将介绍如何通过开环和

3、闭环法控制无刷直流电机的速度，无刷直流电机中的永磁体如何作为转子工作，如何使用一个或多个霍尔效应装置来感知转子的位置，如何逐相激活线圈。将代表一种简单而宏伟的无刷直流电机电流控制调制技术。这种调制技术基于准方波电流的生成。下面给出了此技术的优点。1. 非常简单的控制技术方案2. 相位电流保持平衡。3. 电流仅通过一个直流组件控制。关键词：Hall position sensor, Brushless DC motor, Microcontroller- I -Research and implementation on speed control of BLDC motorsAbstract

4、Brushless DC motor has some more advantages as compare to other motors. The desired hardware project is designed for the purpose of implementation on speed control of brushless DC motor by using closed loop control technique. BLDC motor is being used in various applications for example electronic bi

5、kes, spinning, lathes and drilling etc. A precise and effective speed control can be achieved by this designed system. This system is user friendly, user can enter the speed and motor will run at that exact speed. The purpose of designing controller is to track the variations of speed references and

6、 stabilizes the output speed during load variations. The effectiveness of the proposed system is verified by develop simulation model. Open loop, closed loop and microcontroller method to control the speed of BLDC motors will be discussed briefly in this proposed project. Chapter1 is covering the in

7、troduction of BLDC motors and its applications. Chapter2 will cover the components those we will use to control the speed. Hall position sensor, brushless DC motor, microcontroller are being used as a main components. In chapter3 both the open loop and closed loop methods are discussed. In chapter4

8、microcontroller method is discussed. The purpose of this system is to discuss brushless DC motors and its working. In this project we will cover that how to control the speed of brushless DC motor through open and closed loop method, how a permanent magnet in brushless DC motor works as a rotor, how

9、 to sense the position of rotor by using one or more Hall effect devices, how to activate coils phase by phase. A simple and magnificent current controlled modulation technique of brushless DC motors will be represented. This modulation technique is based on the generation of Quasi-square wave curre

10、nt. Advantages of this technique are given below.1. Very simple control technique scheme2. Phase current are kept balanced.3. The current is only controlled through one DC component.Keywords: Hall position sensor, Brushless DC motor, Microcontroller目录中文摘要IAbstractII目录IIIContentsIV1 BLDC电机的介绍11.1结构和驱

11、动电路11.2起源11.3驱动电路41.4应用82用于控制 BLDC 电机速度的元件142.1目的142.2动机142.3 BLDC 的 MATLAB 模型142.4三相桥逆变器152.5三相逆变器162.6选择 power 开关元件182.7三相桥式逆变器的MATLAB型号192.8输出波形203 BLDC速度控制分析223.1 BLDC电机驱动器的开环控制223.2 BLDC电机的开环控制233.3 BLDC电机的闭环控制254使用微控制器控制 BLDC 的速度274.1介绍274.2 BLDC电机的控制技术274.3施工和运营原则284.4 BLDC 电机速度控制304.5 BLDC电机

12、的逻辑操作314.6各种 PWM 脉冲的仿真结果334.7硬件设置354.8操作过程355结论及未来工作365.1结论365.2今后的工作36引用37Contents中文摘要IAbstractII目录IIIContentsIV1 Introduction of BLDC motors11.1 BLDC motors11.2 Structure and drive circuits11.3 Drive circuits41.4 Applications82 Components to control the speed of BLDC motors142.1 Objective142.2 Mot

13、ivation142.3 MATLAB model for BLDC142.4 Three-phase bridge Inverter152.5 Three-phase Inverter162.6 Selection of power switching element182.7 MATLAB model for three-phase bridge inverter192.8 Output waveform203 Speed Control Analysis223.1 Open loop control of BLDC motor drive223.2 Open loop control o

14、f BLDC motors233.3 Closed loop control of BLDC motors254 Speed Control of BLDC using Microcontroller274.1 Introduction274.2 Control Techniques of BLDC motors274.3 Construction and operating principle274.4 BLDC motors speed control284.5 Logical operation of BLDC motors304.6 Simulation results for var

15、ious PWM pulses314.7 Hardware Setup334.8 Operation procedure355 Conclusion and future work355.1 Conclusion365.2 Future work36References37- IV -1 Introduction of BLDC Motors1.1 BLDC MotorsConventionally DC motors are extremely and fully efficient and due to having special characteristics these DC mot

16、ors are used as servomotors. But they have only drawback that is they need a commutator and brushes. These commutators and brushes are required for maintenance. With the help of solid-state switches when functions of brushes and commutators implement then maintenance free for motor were realized. Th

17、ese motors are being known brushless DC motors.In this chapter we will have look at basic structure, drive circuits, fundamental principles, steady state characteristics, and applications of brushless DC motors.1.2 Structures and drive circuits(1) Basic StructureIf you will analyze then you will fin

18、d that the construction of modern brushless motors is quite similar to the AC motors. These motors are also known as the permanent synchronous motors. Structure of a typical three-phase brushless DC motors has been explained in the given picture below, see figure 1.1. The windings of stator is simil

19、ar to the windings of polyphase AC motors. Permanent magnet are being used to compos rotor. Brushless DC motors are synchronous motors are quite different. The former incorporates is used to detect the position of rotor (or magnetic poles) for the purpose of producing signals to control the electron

20、ic switches as shown in picture below, see figure 1.2. Hall element is the most ordinary position/pole sensor, but optical sensors are being used in some motors.Figure 1.1 Disassembled view of a brushless dc motorFigure 1.2 Brushless dc motor = Permanent magnet ac motorThree-phase motors are most ef

21、ficient and orthodox. For the purpose of driving circuit and simple construction two-phase brushless DC motors are also being used commonly. The picture is given below is showing the cross-section of a two-phase motor having auxiliary salient poles, see figure 1.3.Figure 1.3 Two-phase motor(2) Compa

22、rison of BLDC and conventional Motors According to their static characteristics brushless DC motors and conventional DC motors are quite similar, but in some aspects actually they have remarkable difference. In terms of present-day technology when we compare both motors then a discussion of their di

23、fferences will be more helpful to understand their specific application as compare to their similarities. Table1 is showing the comparison of two types of motors. When we discuss the functionalities of electrical motors then we should not skip the significance of commutation and windings. A process

24、takes place due to commutation which converts the input direct current to alternating current and distributes it in each winding of armature properly. Commutation is undertaken due to brushes and commutator in conventional DC motors. It is done with the help of using semiconductor such as transistor

25、s in brushless DC motors.Table 1. Comparison of conventional motors and BLDC motors Conventional motorsBrushless DC motorsMechanical structureDistinctive featuresWinding connectionsCommutation methodDetecting method of rotors positionReversing methodField magnet on the statorQuick response and excel

26、lent controllability.Ring connection The simplest: Delta connection.Mechanical contact between brushes and commutatorAutomatically detected by brushesBy a reverse of terminal voltageField magnets on the rotor to AC synchronous motor long-lasting.Easy maintenance (usually no required maintenance).The

27、 highest grade: Delta or Y-connected three-phase connection The simplest: Two-phase connectionElectronic switching using transistor.Hall element, optical encoder etc.Rearranging logic sequencer.1.3Drive circuits(1) Unipolar drive Illustration of a simple three-phase unipolar-operated motor that uses

28、 optical sensor (photo transistor) as a position detector is shown in fig below, see figure 1.4. There is a 120 degree interval between all three phototransistor PT1, PT2 and PT3 and they light up in a sequence through a revolving shutter coupled to the motor shaft.The north pole of the rotor and sa

29、lient pole P2 of the stator are facing each other. The photo transistor PT1 will detect the light and turn on transistor TR1. In this condition, the South Pole that is produced at the salient pole P1 due to the electrical which flows through the winding W1 and attracts the north pole of the rotor fo

30、r the purpose of moving it in the arrow direction. When North Pole comes to the state to face the salient pole P1, then PT1 will be shaded, and PT2 will turn on the light and current will flow through transistor TR2. When current passes through winding W2, a salient pole P2 will be created on South

31、Pole, then North Pole in the rotor will start revolving in the direction of arrow and face the salient pole P2. At this instant, the shutter shades PT2 and phototransistor PT3 will exposed to the light. The current will steer from W2 to W3 due to these actions. Thus the salient pole P2 will be DE en

32、ergized, while the salient pole P3 will be energized and the South Pole will be created. So the North Pole on the rotor will travel from P2 to P3 without any disturbance. When this switching action will be repeated in sequence then the permanent magnet rotor will revolve continuously. Figure 1.4 Thr

33、ee-phase unipolar-driven brushless dc motorFigure 1.5 Switching sequence and rotation of stators magnetic field(2)Bipolar DriveWhen a three-phase (brushless) motor will be driven by a three-phase bridge circuit then the efficiency which is the ratio of the mechanical output power to the electrical i

34、nput power will be the highest. So an alternating current in this drive through each winding as an AC motor. Sometimes this drive is referred to as bipolar drive. Here, the meaning of bipolar is an alternatively energized winding in the north and south poles. Picture below is showing the principal s

35、urvey of three-phase bridge circuit, see figure 1.6. Here also we will use the optical method for the purpose of detecting the rotor position. Six phototransistor will be placed at the end of plate with equal intervals. A shutter will be coupled to the shaft. All these elements will be exposed in se

36、quence to the light emitting by a lamp which is placed in the left of the figure. Now we will face a problem which is the relation between ON/OFF state of the transistor and the phototransistor for the light detecting. The simplest relation will be set up when a logic sequencer will be arranged in a

37、 way when a phototransistor marked with a certain number to lighting up. The transistor those have same number will be turn ON. See figure 1.6, shows that electrical current is flowing through Tr1, Tr4 and Tr5, and terminal W and U have the battery voltage, but V terminal containing zero potential.

38、In this position, current will flow from U to V, and a current from W to V is explained in picture, see figure 1.6. Direction of magnetic field in this figure can be assumed that the solid arrows which is being generated by the current in each phase. The resultant magnetic field in the stator is bei

39、ng shown by fat arrow.Figure 1.6 Three phase bipolar-driven brushless motorDue to rotor the placed position of the rotor the field flux will have 90 degree angle according to the stators magnetic field as shown in picture, see figure 1.7. Figure 1.7 Stators magnetic field in the shutter state In thi

40、s state on the rotor a clockwise torque will be produced. When it will revolve about 30 degree then PT5 will be turned OFF and PT6 will be turned ON that will make the stators magnetic pole revolve about 60 degree clockwise. For creating a continuous clockwise rotation the stators South Pole goes aw

41、ay when the rotors South Pole gets near. The sequence of ON-OFF and rotation of the transistor are shown in picture, see figure 1.8.Figure 1.8 Clockwise revolutions of the stators magnetic field and rotor When a photo detector will be marked up with a certain to lighting up, when a logic sequencer w

42、hich set up in a way then the rotational direction may be reversed by arranging this logic sequencer. The transistor of the same number will be turned OFF. But on the other hand when a phototransistor will not light up then the transistor of the same number will be turned on. It is clearly shown in

43、picture, see figure 1.9, that Tr2, 3 and 6 are ON, the battery voltage E appears at voltage V1, while V and U are having zero potential. As shown in figure 1.9 (a) the direction of magnetic field of the stator is reversed, and the rotors torque is counter-clockwise. When motor will revolve around 30

44、 degree, Tr2 turns OFF and Tr1 ON. At this position the field has been revolved about 60 degree, see figure 1.9 (b). when the rotor will produce another counter clock-wise torque, then the counter clockwise motion remains continue and the state of field is shown in picture, see figure 1.9 (c). this

45、action will be replaced in sequence of (a), (b), (c), (d). To produce a continuous counter-clockwise motion.Figure 1.9 Counter-clockwise revolutions of the stators magnetic field and rotorThe motor which we discussed above has delta connection windings. It also can have Y-connection windings. Figure

46、 1.9 (a) is showing the practical circuit which is being used in a laser-beam printer or a hard-disk drive. For detecting magnetic poles, three Hall elements are placed at intervals of 60 degrees. The reason is this motor consists of four magnetic poles, a mechanical angle of 60 degree will correspo

47、nd to an electrical angle of 120 degree.1.4Application Brushless DC motors are being used widely in various kinds of applications. Here we will discuss two application as an example.(1) Laser-printerIn a laser beam printer, a polygon mirror is directly connected to the motor shaft and its speed can

48、be easily controlled accurately within the range 5000 and 40,000 rpm. When a laser beam which is intensity-modulated strikes the revolving polygon mirror, the reflected beam travels in different directions and it depends on the position of the rotor at that moment. So thats why this reflected beam can be used for scanning as