电机是使机械能与电能相互转换的机械，直流电机把直流电能变为机械能。作为机电执行元部件，直流电机内部有一个闭合的主磁路。主磁通在主磁路中流动，同时与两个电路交联，其中一个电路是用以产生磁通的，称为激磁电路，另外一个是用来传递功率，称为功率回路或者电枢回路。-Motor is to convert between mechanical energy and power of machinery, the DC to DC motor into mechanical energy. Executive Yuan as the mechanical and electrical components, DC motor inside the main magnetic circuit has a closed. The main magnetic flux flowing in the main magnetic circuit, while cross-linked with the two circuits, one circuit is used to generate magnetic flux, called the exciting circuit, another one is used to transfer power, known as the power circuit or the armature circuit .