同步发电机转子的励磁 Excitation of synchronous generator rotor

发电机的形式很多，但其工作原理都基于电磁感应定律和电磁力定律。因此，其构造的一般原则是：用适当的导磁和导电材料构成互相进行电磁感应的磁路和电路，以产生电磁功率，达到能量转换的目的。

发电机的分类：

直流发电机、交流发电机、同步发电机、异步发电机(很少采用)；交流发电机还可分为单相发电机与三相发电机。

  所谓励磁即是向同步发电机转子提供直流电使其产生直流电磁场的过程。同步发电机转子凹槽内的线圈就是由称做励磁机的一个专门的设备为其供以直流电形成直流磁场的。早期的发电机是采用单独的励磁机给转子线卷提供直流电的系统庞大而复杂。随着技术的进步现代同步发电机都是将发电机与励磁机组装在一起构成一个完整的发电机。

  励磁机其实就是个小发电机它的工作原理与同步发电机一样。所不同的是它的定子线圈和转子线圈所起的作用与同步发电机--主发电机正好相反;固定在主发电机定子旁的励磁机的定子线圈迫以直流电形成直流磁场，而安装在主发电机转子轴上的励磁机的转子线圈成为输出电动势的电枢。励磁机的转子与定子内壁之间也是保持着小而均匀的间隙。这也称为旋转电枢式结构的无刷同步发电机。安装在主发电机定子旁的励磁机定子线圈的直流电是由主发电机定子线圈即电枢的部分输出电压经整流后而得到的。与主发电机转子同轴安装的励磁机转子线圈在其定子线圈产生的磁场内旋转、切割磁力线所产生的感应电动势,经同轴安装在它旁边的整流器也就是旋转整流器变成直流电流输到主发电机的转子线圈使其产生直流转子磁场。从而达到了对主发电机转子线圈励磁的要求。

There are many forms of generators, but their working principles are based on the laws of electromagnetic induction and electromagnetic force. Therefore, the general principle of its construction is to use appropriate magnetic and conductive materials to form magnetic circuits and circuits that induce each other electromagnetically, in order to generate electromagnetic power and achieve energy conversion.

Classification of generators:

DC generator, AC generator, synchronous generator, asynchronous generator (rarely used); AC generators can also be divided into single-phase generators and three-phase generators.

The so-called excitation refers to the process of providing direct current to the rotor of a synchronous generator to generate a direct current electromagnetic field. The coil inside the rotor groove of a synchronous generator is supplied with direct current by a specialized device called an exciter to form a direct current magnetic field. Early generators were large and complex systems that used a separate exciter to provide direct current to the rotor coils. With the advancement of technology, modern synchronous generators assemble the generator and exciter together to form a complete generator.

The exciter is actually a small generator, and its working principle is the same as that of a synchronous generator. The difference is that its stator coils and rotor coils play the opposite role as a synchronous generator - the main generator; The stator coil of the exciter fixed next to the stator of the main generator is forced to form a DC magnetic field with DC electricity, while the rotor coil of the exciter installed on the rotor shaft of the main generator becomes the armature for outputting electromotive force. There is also a small and uniform gap between the rotor and stator inner wall of the exciter. This is also known as a brushless synchronous generator with a rotating armature structure. The direct current of the excitation machine stator coil installed next to the main generator stator is obtained by rectifying the output voltage of the armature of the main generator stator coil. The excitation machine rotor coil installed coaxially with the main generator rotor rotates within the magnetic field generated by its stator coil, and the induced electromotive force generated by cutting magnetic field lines is converted into direct current through the rectifier installed coaxially next to it, that is, the rotating rectifier, and transmitted to the rotor coil of the main generator to generate a direct current rotor magnetic field. Thus achieving the requirement for excitation of the main generator rotor coil.