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Closed-loop stepping servo system

Abstract: Closed Loop Stepping servo system as a traditional open-loop stepper systems innovation for higher safety, reliability or quality requirements of the application provides a cost-effective choice. Stepper motors installed in the back of a position feedback device or by way of some form of indirect parameter detection position as the same closed-loop servo system, with more experience or control out of step, detecting motor stall, and to ensure that the motor at a higher speed accuracy and more effective torque output.



Into the servo system has the following advantages:

1. greatly enhance the effective torque and speed stepper motor, stepper motor to further expand the scope of application

At the same voltage and current controlled conditions, as opposed to the traditional open-loop stepper systems, closed loop speed range stepping servo system runs smoothly 0.1-3000RPM, effective torque increase to more than 60% holding torque, temperature and noise while lowering.


2. To achieve device miniaturization and high-speed

a. high acceleration and deceleration response, high-speed precision positioning

In the case of the stepping motor 90 short-stroke reversible, T-type deceleration up 10000rad / s / s, speeds up to 800rpm, positioning time <80ms, 1 min roundtrip frequencies up to 700 times, still ensure that the target position accurately.


b. The system miniaturization

As the stepper motor at low speeds when the torque is greater, compared with the conventional servo motor, it can be used in low-speed rotation area larger continuous torque, and therefore the size of the system can achieve miniaturization.


3. Zero speed completely stopped

Due to the holding torque stops the stepping motor characteristics, unlike the servo system to stop when there is micro vibration motor can be achieved and therefore completely stopped, in order to improve the repeatability of positioning accuracy motion systems.


4. High-resolution

500,1000,2000,4000,5000,20000P / R encoder resolution options, up to the position command 80 000 pulses per revolution resolution


5. reduce motor heating, high efficiency

As a result of the closed-loop sinusoidal vector control, as with the servo motor current is controlled according to the size of the load, thereby reducing motor heating and lower motor operating temperature, high efficiency


Increased costs are worth the money?

Closed-loop stepper systems while access to many benefits, but it will bring a little extra cost. But compared with other closed-loop motion control technology, the increase in the cost of a little feedback device, the closed-loop servo system is still stepping cost-effective solution. To ensure the accuracy of the results, pay this extra cost is worth it. The cost of the loss of important applications brought by an error will be far higher than the cost of the feedback element. An encoder or resolver like an advance insurance, make us confident that the stepping motor in the correct position.

Improve the accuracy and quality of the parts from the closed-loop control, the method is to compare the actual measurement position and the ideal location of the machine or motion system. If there is an inconsistency between the two, the motor will motion to compensate for any loss of step. Costs and benefits of a closed-loop feedback system and method is reasonable will depend on the specific application. How much to pay the extra cost of machine performance depends on the desired productivity, the desired positional accuracy and part quality.

Material during the alleged value will affect the balance of the cost. Stepper motors are often used to handle very expensive materials, from electronic components to DNA samples, in order to prevent failure occurs and add a little extra cost is worth the motor feedback.

Market outlook:

Generally believe that stepping servo system in between traditional open-loop stepper and servo in cost, performance, without much market value at all. However, we believe that the high cost stepping servo system, small size, high dynamic response characteristics has irreplaceable advantages in short stroke, high speed reversing applications, both open-loop stepper unable to meet achieve performance requirements, compared to AC servo system with a small, low-cost advantages, especially for applications in the semiconductor, textile, medical, automation equipment, numerical control industry some special requirements, and therefore has a broad market prospect.