What is the difference between step motor control and servo motor control?

Answer:

The torque characteristics are different The output torque of the stepping motor decreases with the speed of the revolution, and falls sharply at high speed, so the maximum working speed is 300 ~ 600RPM. Ac servo motor for constant torque output, that is, at its rated speed (2000 RPM and 3000 RPM) of less than, can be rated output torque and constant power output above the rated speed for. Four, overload ability is different The step motor is generally not overloaded. Ac servo motor has the capability of overload. With the example of the panasonic ac servo system, it has the capability of speed overload and torque overload. The maximum torque is three times the rated torque, which can be used to overcome the moment of inertia of the inertia load. Stepper motor because there is no this kind of overload capacity, in order to overcome the inertia moment when selection, often need to select a larger torque of the motor, and the machine during the normal work and don't need that big torque, there is a moment of waste phenomenon.

Low frequency characteristics In low speed, the step motor is prone to low frequency vibration. The vibration frequency is related to the load condition and drive performance, and the frequency of vibration is generally considered to be half the frequency of the motor. The low-frequency vibrations, determined by the principle of stepping motor, are very bad for the normal operation of the machine. When the stepper motor work in low speed, general damping technology should be adopted to overcome the low frequency vibration phenomenon, such as add damper on motor, or drive the segmentation technology, etc. Ac servo motors are very stable, even at low speeds. Ac servo system has a resonance suppression function, can cover the mechanical rigidity, and internal system has the function of frequency resolution (FFT), can detect the mechanical resonance point, is advantageous for the system adjustment.

Different control accuracy Two-phase hybrid stepper motor step Angle is 3.6 ° and 1.8 °, 5 phase hybrid stepping motors interval Angle is 0.72 ° and 0.36 ° in general. There are also some high performance steps in the step of the motor. The control accuracy of ac servo motor is guaranteed by rotating encoder on the back end of the motor shaft. Panasonic digital ac servo motor, for example, in line with standard 2500 encoder of the motor, drive due to the internal used four frequency multiplication technology, the pulse equivalent to 360 ° / 10000 = 0.036 °. For with 17 encoder of the motor, drive each receive 217 = 131072 pulse motor turns a circle, namely the pulse equivalent to 360 ° / 131072 = 9.89 seconds. Interval Angle is 1.8 ° is 1/655 of the pulse equivalent of stepper motor.

Stepping motor is an actuator that converts electrical impulses into angular displacement. Popular point: when the stepper driver receives a pulse signal, it is driving a stepper motor according to set the direction of a fixed Angle (and the step Angle). You can control the amount of angular displacement by controlling the number of pulses, so that the target is accurate. At the same time, you can control the speed and acceleration of the motor by controlling the pulse frequency. , servo motor, also called executive motor in the automatic control system, is used as actuators, converts the received electrical signal into angular displacement or velocity of motor shaft output.