DC shunt motor commutation circuit

The field coil and armature of the DC shunt motor are connected in parallel, as shown in Figure (a). If the positive and negative poles are reversed at the same time, it is impossible to change the direction of rotation of the motor. Therefore, like a separately excited motor, the direction of rotation can be changed by simply changing the wiring of the armature or excitation coil. Figure (b) is a circuit diagram of changing the excitation coil wiring to achieve motor commutation.