The difference between stepping motor and servo motor
Servo motors, also known as executive motors, are used as actuators in automatic control systems to convert received electrical signals to angular displacement or angular velocity output on the motor shaft. Servo motor rotor is permanent magnet drive control of the U/V/W three-phase power electromagnetic fields, the rotation of the rotor in the magnetic field, and the motor with encoder feedback signal to the drive, the drive according to the feedback value is compared with the target value, the rotating rotor angle adjustment. The servo motor precision depends on the precision of encoder (line number) is a servo motor itself with pulse function, it rotates an angle, will emit pulses corresponding to the number of such servo driver and servo motor encoder pulse forming the echo, so it is a closed loop control, stepper motor drive loop control.
Stepper motor is the electric pulse signal into angular displacement or linear displacement of the open-loop control element of stepper motor, in the case of non overloaded, the motor speed and stop position depends only on the pulse frequency and pulse number, regardless of load changes, when the stepper drive the processor receives a pulse signal, it drives stepper motor, set the direction of rotation of a fixed angle called the step angle, it is the rotation of the fixed point of the operation step by step. Number of pulses can be controlled by controlling the angular displacement, so as to achieve the purpose of accurate positioning, also can control the pulse frequency to control the motor rotation speed and acceleration, so as to achieve the purpose of speed.
The difference between stepping motor and servo motor is as follows: 1. The control accuracy is different. The more the phase number and the number of beats of the stepper motor, the higher the accuracy of the servo motor, and the more the scale of the encoder, the higher the accuracy of the encoder. 2, different control methods; one is open-loop control, and one is closed loop control. 3, the low frequency characteristics of different stepper motor; low frequency vibration phenomenon occurs easily at low speed, it adopts damping technology when the general work or subdivision technology at low speed to overcome the phenomenon of low frequency vibration, servo motor running smoothly, even in low speed does not appear when the phenomenon of vibration. AC servo system has resonance suppression function, it can cover mechanical rigidity shortage, and the system has frequency analysis function (FFT), it can detect the resonance point of the machine, and it is easy to adjust the system. 4, different frequency; the stepper motor output torque will decrease with the increase of speed, the AC servo motor for constant torque output, 5, overload capacity different; stepping motor has not overload capacity, AC motor has strong ability of overload. 6, the performance is different; step motor control for open loop control, the start frequency is too high or too much load lose steps or blocking phenomenon, off high speed is prone to overshoot, AC servo drive system for closed-loop control, the driver can be directly fed back to the motor encoder signal sampling, internal a position loop and speed loop, is generally not a stepping motor lose step or overshoot phenomenon, the control performance is more reliable. Seven
