What is the characteristic of step motor? Compared with dc motors, what advantages does it have?
The cost is low, the drive simple: because it is open loop control, saves the feedback device such as coder, so simplify the system composition, can reduce the cost effectively again. However, the rotation of the step motor is a fast and repetitive "start-stop-start-stop" process, so the rotational smoothness is not as good as the dc motor. The step motor also has a resonant frequency, and when the motor is working at a certain speed interval, the driven pulse may be tuned to cause the motor to shake. In addition, in the event of a pulse to drive motor (commonly known as "step", may appear because of the interference signal, etc), the open loop system and compensation cannot be detected. The problem can be solved by adding coders, but it will lead to higher costs and more complex drivers.
Small volume, long service life, the life of the stepper motor usually depends on the bearing life, can reach tens of thousands to tens of thousands of hours, compared with the equivalent size of the dc motor, stepper motor output torque is bigger.
No coder and other feedback devices can be used to control the speed and Angle (i.e. open loop control), which is the most characteristic of stepping motor. The frequency of the pulse determines the speed of the motor, and the number of pulses determines the Angle of the motor. The dc servo system is the following advantages: 1, the locking position, motor power consumption: no longer stepping motor characteristic of the "static torque" (also called "holding torque", "localization" torque, etc.), when the motor stopped in a certain position, locking torque. The dc motor can also lock the position through the drive, but the motor still consumes power when locked.
