The physical symbols of servo motors and stepper motors are SM and PM, VR, HB, respectively.
There are three types of stepper motors: permanent magnet (PM), reactive (VR) and hybrid (HB).
Servo motor (SM) refers to the engine that controls the operation of mechanical elements in the servo system, and is an indirect transmission device that supplements the motor.
The servo motor can control the speed, the position accuracy is very accurate, and the voltage signal can be converted into torque and speed to drive the control object. The rotor speed of the servo motor is controlled by the input signal, and can respond quickly, in the automatic control system, used as an executive element, and has the characteristics of small electromechanical time constant, high linearity, starting voltage, etc., which can convert the received electrical signal into angular displacement or angular velocity output on the motor shaft.
Divided into two categories: DC and AC servo motors, its main feature is that when the signal voltage is zero, there is no rotation phenomenon, and the speed decreases uniformly with the increase of torque.
Permanent magnet stepper motor is generally two-phase, torque and volume are small, the step angle is generally 7.5 degrees or 15 degrees; the reactive stepper motor is generally three-phase, which can achieve large torque output, and the stepping angle is generally 0.75 degrees. The output torque is large and the speed is relatively high. This kind of motor is used more in machine tools.
Hybrid stepper motor refers to a combination of permanent magnet and reactive advantages.
It is divided into two-phase, three-phase, four-phase and five-phase: the two-phase (four-phase) step angle is generally 1.8 degrees, the three-phase step angle is usually 1.2 degrees, and the five-phase step angle is mostly 0.72 degrees. At present, hybrid stepper motors are the most widely used.
DC servo motors can be used in spark machines, manipulators, precision machines, etc. It can be equipped with a standard encoder and tachometer with high analysis of 2500P/R at the same time, and can be equipped with a gearbox, so that the mechanical equipment brings reliable accuracy and high torque.
Good speed regulation, unit weight and volume, the output power is the highest, greater than AC motor, far more than stepper motor. The torque fluctuation of the multi-stage structure is small.