What is the difference between ac servo motor and three-phase ac asynchronous motor?
Stepper motor is the electrical pulse signal into angular displacement or line displacement of the stepper motor open-loop control yuan, in the case of the overload, motor speed, stop position depends only on the pulse signal frequency and pulse number, and not affected by load change, when the stepper driver receives a pulse signal, it is driving a stepper motor, set the direction of a fixed Angle, known as the "step Angle", its rotation is based on the Angle of the fixed step by step.
Generally speaking: Servo motor is able to accurately realize position, speed, torque control Ac asynchronous motor is used for general power output.
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. Such as cross company produces a kind of stepping motor for wire walking machine, where the step Angle is 0.09 °. BERGER LAHR company in Germany (BERGER LAHR) production of three-phase hybrid stepping motor where the step Angle can dial the code switch is set to 1.8 ° and 0.9 ° and 0.72 ° and 0.36 ° and 0.18 ° and 0.09 ° and 0.072 ° and 0.036 °, combine the two and five phase hybrid stepper motor step Angle. 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.
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.
