DC motor

The excitation method of a DC motor refers to the problem of how to supply power to the excitation winding, generate excitation magnetic flux, and establish the main magnetic field. According to different excitation methods, DC motors can be divided into the following types. The separately excited excitation winding is not connected to the armature winding, and a DC motor powered by other DC sources is called a separately excited DC motor. The wiring is shown in Figure 1.23 (a). M in the figure represents the electric motor, and if it is a generator, it is represented by G. Permanent magnet DC motors can also be regarded as separately excited DC motors. The excitation winding of a parallel excited DC motor is parallel to the armature winding. As a parallel excitation generator, the terminal voltage generated by the motor itself supplies power to the excitation winding; As a parallel excited motor, the excitation winding and armature share the same power source, which is the same in performance as a separately excited DC motor. The excitation winding of a series excited DC motor is connected in series with the armature winding before being connected to a DC power source. The excitation current of this DC motor is the armature current. A compound excitation DC motor has two excitation windings: parallel excitation and series excitation. If the magnetic flux generated by the series excitation winding has the same direction as the magnetic flux generated by the parallel excitation winding, it is called integral compound excitation. If two magnetic flux potentials have opposite directions, it is called differential compound excitation. DC motors with different excitation methods have different characteristics. In general, the main excitation methods for DC motors are parallel excitation, series excitation, and compound excitation. The main excitation methods for DC generators are separate excitation, parallel excitation, and compound excitation.