The difference between permanent magnet stepper motor permanent magnet servo motor

1, the stepper motor servo motor discussed in this paper are permanent magnet AC motors.

The main driving principle of permanent magnet AC motor is that the rotor is a permanent magnet, the stator is a changing electromagnetic field. By changing the electromagnetic field to drive the rotor rotation, that is, the motor shaft rotation. Simply put, the stator magnetic field turns 30 degrees, the rotor magnet is attracted by the magnetic field force to turn 30 degrees.

The essence of permanent magnet stepper motor permanent magnet servo motor is that through the time-size relationship of the current, the time-direction-size relationship of the electromagnetic field is acted on, the relationship of the time - direction - displacement - torque of the rotor is further affected, the rotor is realized to reach the specified position in accordance with the corresponding requirements. Stepper motor is a simple displacement positioning, servo motor is the use of current - space time integral = speed, speed - space time integral = displacement, displacement feedback judgment, three rings to obtain a good process control.

Science develops step by step. Scientists the use of fixed magnet stator + DC coil + commutator DC motor to achieve electric rotation, step by step development, can accurately control the motor to the designated position? Then he invented the stepper motor, which is given a position, he can reach that position. Later, can you still control the process of the motor to the specified position, that is, the speed? Then invented the servo motor, that is, you can control the electric, how long to reach how long displacement.

Historically, it will be found that there is a difference between the willingness of scientists to invent stepper motors servo motors. Stepper motors are basically realized positioning displacement without the need to consider the process. The servo motor is the process of achieving displacement simultaneously.

Different goals lead to different results.

1, stepping motor. The upper PLC handles the motor process, whether the motor is in place, the speed process, the driver is only responsible for sending pulses.

2, permanent magnet servo motor. The upper computer PLC only tells the driver, speed instructions displacement instructions, while the driver itself handles the motor in place the speed process.

The result is that the stepper motor draws the motor to the specified position through a target suction, which is completed, the PLC finds a way to reach the position by itself. The servo motor, the whole process drive to keep sampling, calculation adjustment, to obtain a good acceleration deceleration uniform speed process, after reaching the position, tell the PLC to, then no brake ready to the next command.

Differences in mechanical principles cause differences in use.

1, the purpose of preset positioning, is to move to the designated place, stop. This is better with a stepper motor than a servo motor. For example, the CNC feed of the grinder, the bevel Angle of the glass grinding edge, the length of the fixed size of the cutting material, so on.

2, the purpose of reciprocating motion is that the displacement is changing. This is good with a servo motor. Such as XY axis synchronous movement, robot hand so on.