Advantages and disadvantages of DC servo motors, AC servo motors and stepper motors
In order to adapt to the development trend of digital control, stepping motor, DC motor or all-digital AC servo motor is mostly used as the execution motor in the motion control system. Although the three are similar in control, there are differences in performance and application. Now Dalan Motor Xiaobian compares the advantages of the three.
AC servo motor
advantage:
(1) There are no brushes and commutators, so the work is reliable and the maintenance and maintenance requirements are low.
(2) The stator winding heat dissipation is convenient.
(3) The inertia is small, which is easy to improve the rapidity of the system.
(4) Adapted to high speed and large torque working conditions.
DC servo motor
advantage:
DC servo motor refers to DC brushed servo motor - high motor cost, complex structure, large starting torque, wide speed range, easy control, maintenance, but inconvenient maintenance (replacement of carbon brushes), electromagnetic interference will occur. The environment is required. It can therefore be used in cost-sensitive general industrial and residential applications.
DC servo motor does not include DC brushless servo motor - the motor is small in size, light in weight, large in output, fast in response, high in speed, small in inertia, smooth in rotation, stable in torque, and limited in motor power. It is easy to realize intelligence, and its electronic commutation mode is flexible, and it can be commutated by square wave or sine wave. Motor maintenance-free, there is no carbon brush loss, high efficiency, low operating temperature, low noise, small electromagnetic radiation, long life, and can be used in various environments.
use:
(1) Actuator drive in various digital control systems.
(2) Power drive that requires precise control of constant speed or precise control of the speed change curve.
According to the motor inertia size can be divided into:
(1) Small inertia DC motor - automatic drilling machine for printed circuit boards
(2) Medium inertia DC motor (wide speed DC motor) - feed system of CNC machine tools
(3) Large inertia DC motor - spindle motor of CNC machine tools
(4) Special form of low inertia DC motor
Stepper motor
advantage:
(1) The angle of rotation of the motor is proportional to the number of pulses;
(2) The maximum torque is available when the motor is stopped (when the winding is energized);
(3) Since the accuracy of each step is between 3% and 5%, and the error of one step is not accumulated to the next step, there is better positional accuracy and repeatability of motion;
(4) Excellent start and stop and reverse response;
(5) Since there is no brush, the reliability is high, so the life of the motor depends only on the life of the bearing;
(6) The response of the motor is determined only by the digital input pulse, so open loop control can be used, which makes the structure of the motor relatively simple and controls the cost;
(7) It is also possible to directly rotate the load directly to the rotating shaft of the motor at a very low speed;
(8) Since the speed is proportional to the pulse frequency, there is a relatively wide range of speeds.
defect:
(1) If the control is improper, it is easy to generate resonance;
(2) It is difficult to run to a higher speed;
(3) It is difficult to obtain a large torque;
(4) There is no advantage in terms of volume and weight, and energy utilization is low;
(5) When the load is exceeded, the synchronization is destroyed, and vibration and noise are generated at high speed.
In summary, the AC servo system is superior to the stepper motor in many performance aspects. However, in some occasions where the requirements are not high, stepper motors are often used to perform the motor. Therefore, in the design process of the control system, it is necessary to comprehensively consider the control requirements, cost and other factors, and select the appropriate control motor.
