A servo motor refers to an electric motor that controls the operation of mechanical components in a servo system. It can be divided into two types: DC servo motors and AC servo motors. The differences between these two types of servo motors are mainly reflected in the following aspects:
1. Different structures
The structure of an AC servo motor is similar to that of an AC asynchronous motor. There are two excitation windings and a control winding on the stator with a phase space displacement of 90 ° electrical angle. They are connected to a constant AC voltage and use the changes in AC voltage or phase applied to the windings to control the operation of the motor.
The structure of a DC servo motor is similar to that of a DC motor, including a stator, rotor iron core, motor shaft, servo motor winding commutator, servo motor winding, speed motor winding, and speed motor commutator. The rotor iron core is composed of silicon steel laminations laminated and fixed on the motor shaft.
2. The principle is different
The stator three-phase coil of the AC servo motor is powered by a servo coding control circuit, and the rotor is permanent magnet. The direction, speed, and angle of the motor are determined by the coding controller.
The rotor of a DC servo motor is also made of permanent magnets, while the stator winding is powered by a servo encoded pulse circuit.
3. Different classifications
DC servo motors are divided into two types based on the presence or absence of carbon brushes: brushed DC servo motors and brushless DC servo motors; AC servo motors belong to brushless motors, which are divided into synchronous and asynchronous motors.
4. Different control methods
There are three control methods for AC servo motors: amplitude control, phase control, and amplitude phase control; There are two main control methods for DC servo motors: armature voltage control and excitation field control.
5. Different maintenance costs
Convenient maintenance of communication servo motors; DC servo motors are easy to achieve speed regulation and high control accuracy, but they have high maintenance costs and are difficult to operate.
6. Different mechanical characteristics
The characteristic of AC servo motors is relatively soft. When the rated torque is reached, if the load torque increases, it is easy to cause sudden stall. However, DC motors have fast response, large starting torque, and the ability to provide rated torque from zero speed to rated speed. Although AC motors do not have carbon brushes and rectifiers, they are maintenance free, sturdy, and widely used. However, to achieve performance equivalent to DC motors in terms of characteristics, complex control technology is required.
