The working principle of a brushed DC motor. There are magnets in the fixed part of the brushed DC motor, which is called the main pole here; there are brushes in the fixed part. The rotating part has a toroidal core and a winding wound on the toroidal core.
A pair of DC-excited stationary main magnetic poles N and S are installed on the fixed part (stator) of the two-pole brushed DC motor, and an armature core is installed on the rotating part (rotor). There is an air gap between the stator and the rotor. An armature coil composed of two conductors A and X is placed on the armature core. The head and end of the coil are respectively connected to two arc-shaped copper plates, which are called commutating plates. The commutator segments are insulated from each other, and the whole composed of commutator segments is called a commutator. The commutator is fixed on the rotating shaft, and the commutator segments and the rotating shaft are insulated from each other. A pair of fixed brushes B1 and B2 are placed on the commutator. When the armature rotates, the armature coil is connected to the external circuit through the commutator and the brush.