Servo motor VS stepper motor

 Performance comparison of servo motor and stepper motor

1. Different control accuracy

Two-phase hybrid stepper motors generally have step angles of 1.8 ° and 0.9 °, and five-phase hybrid stepper motors generally have step angles of 0.72 ° and 0.36 °. There is also a high-performance stepping motor with a small step angle after subdivision.

The control accuracy of the AC servo motor is guaranteed by the rotary encoder at the rear of the motor shaft. Taking Sanyo's all-digital AC servomotor as an example, for a motor with a standard 2000 line encoder, the 4x frequency technology used in the drive results in pulse equivalence of 360 ° / 8000 = 0.045 °. ..

2. Various low frequency characteristics

Stepper motors are prone to low frequency vibrations at low speeds. This low frequency vibration phenomenon, which is determined by the operating principle of the stepper motor, is very disadvantageous to the normal operation of the machine.

The AC servo motor runs very smoothly and does not vibrate even at low speeds.

3. Different moment frequency characteristics

The maximum operating speed is typically 300-600 RPM, as the output torque of a stepper motor decreases with increasing speed and drops sharply at high speeds.

The AC servo motor has a constant torque output. In other words, the rated torque can be output within the rated speed (usually 2000RPM or 3000RPM), and a constant output can be obtained when the rated speed is exceeded.

4. Four different overload capacities

Stepper motors usually do not have overload capacity.

AC servo motors have a strong overload capacity.

5. Three different operating performances

The control of the stepping motor is open loop control. If the starting frequency is too high or the load is too high, it is easy to lose steps or stall. If the speed is too fast, it will be easy to overshoot.

The AC servo drive system is closed loop control. In general, there is no step loss or overshoot of the stepper motor, and the control performance is highly reliable.

6. Three different speed response performance

It takes 200-400 milliseconds for the stepper motor to accelerate from a standstill to operating speed (usually hundreds of revolutions per minute).

The acceleration performance of the AC servo system is excellent. Taking a 400W AC servomotor as an example, it only takes a few milliseconds to accelerate from a standstill to a rated speed of 3000RPM. It can be used in control situations that require fast start and stop.

In summary, AC servo systems are superior to stepper motors in many aspects of performance. However, stepper motors are often used as executive motors in less demanding situations. Therefore, the control system design process must comprehensively consider various factors such as control requirements and costs to select the appropriate control motor.

https://buycnc.com/cnc-router/4-axis-desktop-cnc-milling-machine/

https://buycnc.com/high-precision-cnc-router-milling-machine/