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1、序言：一个多世纪以来，电动机作为机电能量转换装置，其应用范围已遍及国民经济的各个领域以及人们的日常生活中。其主要类型有同步电动机、异步电动机和直流电动机三种。由于传统的直流电动机均采用电刷以机械方法进行换向，因而存在相对的机械摩擦，由此带来了噪声、火化、无线电干扰以及寿命短等弱点，再加上制造成本高及维修困难等缺点，从而大大限制了它的应用范围，致使目前工农业生产上大多数均采用三相异步电动机。 针对上述传统直流电动机的弊病，早在上世纪30年代就有人开始研制以电子换向代替电刷机械换向的直流无刷电动机。经过了几十年的努力，直至上世纪60年代初终于实现了这一愿望。上世纪70年代以来，随着电力电子工业的飞
2、速发展，许多高性能半导体功率器件，如GTR、MOSFET、IGBT、IPM等相继出现，以及高性能永磁材料的问世，均为直流无刷电动机的广泛应用奠定了坚实的基础。 由于直流无刷电动机既具有交流电动机的结构简单、运行可靠、维护方便等一系列优点，又具备直流电动机的运行效率高、无励磁损耗以及调速性能好等诸多优点，故在当今国民经济各领域应用日益普及。三相直流无刷电动机的基本组成：直流无刷永磁电动机主要由电动机本体、位置传感器和电子开关线路三部分组成。其定子绕组一般制成多相（三相、四相、五相不等），转子由永久磁钢按一定极对数（2p=2,4,）组成。图1所示为三相两极直流无刷电机结构，图1 三相两极直流无刷电
3、机组成三相定子绕组分别与电子开关线路中相应的功率开关器件联结，A、B、C相绕组分别与功率开关管V1、V2、V3相接。位置传感器的跟踪转子与电动机转轴相联结。 当定子绕组的某一相通电时，该电流与转子永久磁钢的磁极所产生的磁场相互作用而产生转矩，驱动转子旋转，再由位置传感器将转子磁钢位置变换成电信号，去控制电子开关线路，从而使定子各项绕组按一定次序导通，定子相电流随转子位置的变化而按一定的次序换相。由于电子开关线路的导通次序是与转子转角同步的，因而起到了机械换向器的换向作用。图2为三相直流无刷电动机半控桥电路原理图。此处采用光电器件作为位置传感器，以三只功率晶体管V1、V2和V3构成功率逻辑单元。
4、 图2 三相直流无刷电动机三只光电器件VP1、VP2和VP3的安装位置各相差120度，均匀分布在电动机一端。借助安装在电动机轴上的旋转遮光板的作用，使从光源射来的光线一次照射在各个光电器件上，并依照某一光电器件是否被照射到光线来判断转子磁极的位置。图3开关顺序及定子磁场旋转示意图 图2所示的转子位置和图3 a）所示的位置相对应。由于此时广电器件VP1被光照射，从而使功率晶体V1呈导通状态，电流流入绕组A-A，该绕组电流同转子磁极作用后所产生的转矩使转子的磁极按图3中箭头方向转动。当转子磁极转到图3 b）所示的位置时，直接装在转子轴上的旋转遮光板亦跟着同步转动，并遮住VP1而使VP2受光照射，从
5、而使晶体管V1截至，晶体管V2导通，电流从绕组A-A断开而流入绕组B-B，使得转子磁极继续朝箭头方向转动。当转子磁极转到图3 c）所示的位置时，此时旋转遮光板已经遮住VP2，使VP3被光照射，导致晶体管V2截至、晶体管V3导通，因而电流流入绕组C-C，于是驱动转子磁极继续朝顺时针方向旋转并回到图3 a）的位置。PreambleMore than a century, electric motors as an electronic and mechanical energy conversion device, its applications cover all areas of the n
6、ational economy and peoples daily life. The main types of synchronous motor, asynchronous motor and three kinds of DC motor. Because of the traditional DC motor using brush by mechanical methods to change, so there is a relatively mechanical friction, the resulting noise, cremation, radio interferen
7、ce, as well as a shorter life-span, such as weakness, coupled with high manufacturing costs and maintenance difficulties disadvantage, thereby greatly limiting its scope of application, with the result that the majority of current industrial and agricultural production are three-phase asynchronous m
8、otor. To address the above drawbacks of the traditional DC motor, as early as the 30s in the last century, some started to develop an electronic exchange to replace the mechanical brush commutation of brushless DC motor. After decades of effort, until the last century, the early 60s finally realize
9、this desire. Since the 70s of last century, with the power electronics industry, the rapid development of many high-performance power semiconductor devices, such as GTR, MOSFET, IGBT, IPM, etc. as well as the advent of high-performance permanent magnet materials are brushless DC motor widely used to
10、 lay a solid foundation. Because of brushless DC motor Motor communicate both simple structure, reliable operation, easy maintenance, such as a series of advantages, but also the operation of DC motor with high efficiency, non-excited, as well as speed performance and wear and tear, and many other a
11、dvantages, it is in todays national economy applications become increasingly popular.Three-phase brushless DC motor of the fundamental componentFigure 1 Three-phase bipolar brushless DC motor componentBrushless DC permanent magnet motor main body by the motor, position sensors and electronic switchi
12、ng circuit is composed of three parts. Its stator windings generally made of multi-phase (three-phase, four-phase, five-phase range), by the permanent magnet rotor according to a certain number of pole pairs (2p = 2,4, .) components. Shown in Figure 1 for three-phase bipolar brushless DC motor struc
13、ture,Three-phase stator windings, respectively, with the electronic switch circuit corresponding link power switching devices, A, B, C phase windings, respectively, with the power switch V1, V2, V3 phase. Rotor position sensor tracking linked with the motor shaft. When the stator windings of a phase
14、 electricity, the current and the rotor permanent magnet poles of the magnetic field generated by the interaction torque generated to drive the rotor rotation position sensor by the rotor magnet position will be converted into electrical signals, to control electronic switch circuit, so that the sta
15、tor windings according to a certain order of conduction, stator phase current with rotor position changes in the order according to a certain phase. Because of the electronic switch the order of conduction lines are synchronized with the rotor angle, which has played a mechanical commutator to the r
16、ole exchange.Figure 2 for the three-phase brushless DC motor-controlled half bridge circuit schematic. Optoelectronic devices used here as a position sensor to three power transistors V1, V2 and V3 constitute a logical unit power.Figure 2 Three-phase brushless DC motor3 optoelectronic devices VP1, VP2 and VP3 of the installation location of the difference between the 120 degr
