What is an ac driver? And the principle! Thank you very much!
Speed response performance is different It takes between 200 and 400 milliseconds for a step motor to accelerate from rest to a working speed (usually a few hundred revolutions per minute). Better acceleration performance of the ac servo system, a panasonic MSMA 400 w ac servo motor as an example, from static accelerated to the rated speed 3000 RPM it takes only a few milliseconds, can be used for quick start-stop control occasions. To sum up, the ac servo system is superior to stepping motor in many performance aspects. But you can also use stepping motors to do the motor on a less demanding occasion. Therefore, in the design of the control system, the factors such as controlling requirements and cost, etc., should be taken into consideration.
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. Three, the moment frequency characteristic is 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.
Overload capability 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. Running performance is different Stepper motor control for the open loop control, start frequency is too high or too much load step easy appear lost or blocked, stops frequently occur high speed overshoot phenomenon, so as to ensure the control accuracy, should handle the ascending and descending speed problem. Ac servo drive system for closed-loop control, the actuator can be directly to the motor encoder feedback signal sampling, internal position loop and speed loop, general won't appear step motor lose step or overshoot phenomenon, more reliable control performance.
Motor servo ac motor drive is also called the implementation, in the automatic control system, is used as actuators, converts the received electrical signal into angular displacement or velocity of motor shaft output. Divided into two major categories of dc and ac servo motor, its main characteristic is, when the signal voltage is zero no rotation, speed decreases with the increase of torque and uniform, Servo actuator is the control part of servo motor.
