What are the methods to control the speed of DC motor? What is the most commonly used? why

The speed regulation of DC motor, that is, speed control, refers to artificially or automatically changing the speed of the motor in the DC transmission system to meet the requirements of working machinery for different speeds. From the point of view of mechanical characteristics, it is to change the mechanical characteristics of the motor by changing the parameters of the motor or the applied voltage, so as to change the intersection with the working mechanical characteristics and change the stable running speed of the motor.

Speed regulation method of DC motor;

1, change the armature circuit resistance for speed regulation.

2, change the armature voltage speed regulation.

3. Change the flux speed adjustment.