Closed-Loop Stepper Control System
Closed-Loop stepper motor and drive High-Speed, High-Precision, High-Reliability Application Solution
Closed-loop stepper (stepper servo/stepping servo) system as an innovation of the traditional open loop stepping drive system provides a cost-effective choice for applications with higher safety, reliability or product quality requirements. A position feedback device is installed behind the stepping motor or a closed loop like the servo system is formed by detecting the position with some indirect parameters, so as to compare or control the out-of-step, detect the motor stall, and ensure that the motor is at a higher speed. , accuracy and greater effective torque output.
Closed-loop stepper (stepper servo/stepping servo) system has the following advantages:
1. Greatly increase the effective torque and speed of stepper motor, and further widen the application range of stepper motor
Under the same voltage and current control conditions, compared with the traditional open-loop stepping system, the speed range of the closed-loop stepping servo system can be smoothly run at 0.1-3000 RPM, and the effective torque is raised to more than 60% of the holding torque. Reduces noise at the same time.
2. To achieve high speed and miniaturization of equipment
a. High acceleration and deceleration response, high-speed precision positioning
In the case of a 90-degree short stroke of a stepping motor(stepper motor) the T-type acceleration and deceleration can reach 10000 rad/s/s, the speed can reach 800 rpm, the positioning time can be less than 80ms, and the 1-minute round-trip frequency can reach 700 times. Ensure accurate positioning of the target position
b. System miniaturization
Since the stepper motor/stepping motor has a large torque at a low speed, a larger continuous torque can be used in a low speed rotation area than a conventional servo motor, so that the system size can be reduced.
3. Completely stopped at Zero speed
Because the stepper motor/stepping motor has a holding torque characteristic when it is stopped, unlike the servo system, there are micro-vibrations when it is stopped, so that the motor can be completely stopped to improve the repeatability of the positioning system
4. High resolution
500,1000,2000,4000,5000,20000P/R encoder resolution selectable, up to 80,000 pulses per revolution position command resolution
5 Reduce motor heat and achieve high efficiency
Because closed-loop sine wave vector control is adopted, like the servo, the motor current is controlled according to the size of the load, thus reducing the motor heating, reducing the motor operating temperature, and achieving high efficiency.
Although the Closed-loop stepper (stepper servo/stepping servo) has obtained many benefits, it brings a little extra cost. However, compared with other closed-loop motion control technologies, even if the cost of a little feedback device is increased, the closed-loop stepping servo system is still a low-cost solution. To ensure the accuracy of the results, it is worthwhile to pay this extra cost. In an important application, the cost loss caused by an error will be much higher than the cost of the feedback component. The role of the encoder or resolver is similar to that of an advance insurance, which allows us to make sure that the stepper motor is working in the correct position.
Improvements in the accuracy and quality of parts originate from closed-loop control by comparing the actual measurement position with the ideal position in a machine or motion system. If there is an inconsistency between the two, the motor will move to compensate for any out-of-step. Whether the costs and benefits of feedback devices and closed-loop methods are reasonable will depend on the specific application. The additional cost to be paid depends on the required machine performance, productivity, positional accuracy, and desired part quality.
The value of materials in the process of being charged also affects the balance of costs. Stepper motors are often used to process very expensive materials. From electronics to DNA samples, it is worth adding a little extra motor feedback to prevent failures.
It is generally believed that the stepper servo /closed loop stepper system is between traditional open-loop stepping motor and AC servo motor in terms of cost and performance, and has little market value. However, we believe that the stepper servo system's cost-effectiveness, small size, and high dynamic response are of irreplaceable superiority in short-stroke, high-speed forward-reverse applications. The achieved performance requirements, compared with the AC servo system with the advantages of miniaturization, low cost, especially suitable for application in the semiconductor, textile, medical, numerical control industry, some special requirements of automation equipment, so it has a broad market application prospects.