The earliest servo motor is a general DC motor. When the control accuracy is not high, a general DC motor is used as the servo motor. The current DC servo motor is structurally a low-power DC motor, and its excitation uses armature control and magnetic field control, but usually uses armature control. There is a spark between the commutator and the brush, which interferes with the operation of the driver. It cannot be used in the case of flammable gas.
There is friction between the brush and the commutator, which will result in a large dead zone structure and difficult maintenance. The above is a two-phase asynchronous motor, and there are three main control methods: amplitude control, phase control and amplitude phase control. Generally, the servo motor requires the rotation speed of the motor to be controlled by the applied voltage signal; the rotation speed can continuously change.
with the change of the applied voltage signal; the reflection of the motor is fast, the volume is small, and the control power is small. With simple structure, high reliability and low cost, stepping motors are widely used in various fields of production practice; especially in the field of CNC machine tools, because the stepping motor does not require A/D conversion, it can directly digitally pulse.
The signal is converted into an angular displacement, so it has always been considered the most ideal CNC machine tool actuator. In addition to its application on CNC machines, stepper motors can also be used on other machines, such as motors in automatic feeders, as general-purpose floppy disk drives, as well as in printers and plotters.