DC compound motor commutation circuit

The excitation winding of this type of motor is composed of a parallel winding L1 and a series winding, as shown in Figure (a). If you want to change the direction of the motor by changing the excitation current, you must change the current directions of L1 and L2 at the same time, but this change is more troublesome. The commonly used method is to change the current direction of the armature winding, that is, to change the wiring at both ends of the armature. In this way, due to the different directions of the armature current, the steering direction of the motor also changes, as shown in Figure (b). It must be noted that if the DC motor housing is marked with an arrow marking the direction of rotation, it is only allowed to run in one direction. This kind of motor is generally not suitable for commutation, otherwise the brush sparks will increase and the commutator will be burned.