We usually use the DC motor in the control, there are mainly two ways of control, in the operation we should understand the DC motor control schematic diagram, here is the following.
There are two main control methods of DC motor: one is armature voltage control, that is, under the constant stator magnetic field, the motor speed and output torque can be controlled by controlling the voltage signals applied to both ends of the armature winding;The other is excitation field control, that is, by changing the magnitude of excitation current to change the stator magnetic field strength, so as to control the motor speed and output torque.
In the armature voltage control mode, since the stator magnetic field remains unchanged, its armature current can reach the rated value, and the corresponding output torque can also reach the rated value, so this mode is also known as the constant torque speed regulation mode.
In the case that the dc motor is controlled by an exciting magnetic field, the speed of the motor can only be changed by weakening the magnetic field because the magnetic field is nearly saturated under the rated operating conditions.As the armature current is not allowed to exceed the rated value, with the weakening of the magnetic field, the motor speed increases, but the output torque decreases, while the output power remains unchanged, so this mode is also known as the constant power speed regulation mode.
The motor is controlled by the current magnetic field, which is the principle of the motor, but dc is closed loop, the process has compensation positioning, so it is stronger than stepping