Comparison between closed-loop control and open-loop control of stepping motor
Comparison between closed-loop control and open-loop control of stepping motors one of the main advantages of stepping motors is that they are suitable for open-loop control.
In the open loop control, the stepping motor is controlled by a pulse sequence with a predetermined time interval, and no feedback sensor and corresponding electronic circuit are required in the control system.
This kind of circuit has the characteristics of simplicity and low cost, which makes the open loop control system of stepping motor widely used.
42 closed-loop stepping motor, however, the open-loop control of stepping motor cannot avoid the inherent shortcomings of stepping motor itself, namely resonance, oscillation, out-of-step and difficulty in realizing high speed.
On the other hand, it is very difficult for the precision of open-loop control stepping motor system to be higher than grading, and its positioning accuracy is relatively low.
Therefore, in systems with high precision and stability standards, a closed-loop control system must be used.
Shenzhen ruite electromechanical Technology Co. , Ltd. is located in Shenzhen, Guangdong province, it is a stepping motor manufacturer integrating research and development, production and sales of stepping motor drivers, servo drivers, stepping motors, servo motors and spindle servo motors.
The closed-loop control of stepping motor adopts position feedback and (OR)
Speed feedback to determine the phase conversion suitable for rotor position can greatly improve the performance of stepping motor.
In a closed-loop controlled stepping motor system, the working speed range can be expanded when tracking and feedback are provided with a given accuracy, or the tracking and positioning accuracy can be improved at a given speed, or the limit speed index and limit accuracy index can be obtained.
Compared with the open-loop control performance, the closed-loop control performance of stepping motor has the following advantages: a.
With the increase of output torque, the speed of both decreases in nonlinear form, but closed-loop control improves the moment-frequency characteristics. B.
After closed-loop control, the output power/torque curve can be improved. The reason is that under closed-loop control, the motor excitation conversion is based on rotor position information, and the current value is determined by the motor load. Therefore, even in the low speed range, the current can be fully converted into torque. c. Closed-loop control improves efficiency-torque curve. d.
Closed-loop control can obtain higher running speed, more stable and smoother rotating speed than open-loop control. e.
Using closed-loop control, the stepping motor can be accelerated and decelerated automatically and effectively. f.
The quantitative evaluation of the improvement of the speed of closed-loop control over open-loop control can be obtained by comparing the time between a certain path in Step IV: n-Stepping Motor conversion beat number (N>n)g. With closed-loop drive, the efficiency can be increased to 7. 5%. 8 times, the output power can be increased to 3. 3 times, the speed can be increased to 3. 6 times.
The performance of closed-loop driven stepping motor is better than that of open-loop driven stepping motor in all aspects.
Closed-loop drive of stepping motor has the advantages of open-loop drive of stepping motor and DC brushless servo motor.
Therefore, closed-loop controlled stepping motors will be widely used in position control systems with high reliability requirements.
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