Control principles and purposes of nema stepper motor

The operation of the nema stepper motor is an electronic device driver, is the angular displacement that the stepper motor control system transforms from pulse signal to stepper motor, or the angle that the stepper motor control system sends a pulse signal and rotates the step stepper motor by driving.

The stepper motor can perform one step at a time, and each step possesses the same size. Each pulse will make the motor rotate with an accurate angle (usually is 1.8°). Thus it can control the position of the motor without any feedback system.

Control principles of the stepper motor

The usual way of controlling the stepper motor is divided into the fluctuation pattern, all-step model, half-step model, and microstep driver. In ideal conditions, the nema motor will appear vibration when using an all-step model, which is not qualified for some applications. On the other hand, the all-step model motor can reach higher torque.

The all-step and half-step modes are the common methods in stepper motor control. These control ways are pretty simple and liable to realize through any control unit. However, it will appear problems in the area of the resonance region, and the motor may go out of step. One solution is to divide the motor stepper into micro-steps, which can better be located and restrict rotors' angular velocity pulsation in the area of low stepper frequency.

When receiving the pulse signal, the stepper motor will rotate the fixed angle (that's the step angle) according to the direction set for the stepper motor. The angular displacement can be controlled by controlling the pulse count to attain an accurate location. Meanwhile, the rotate and accelerated speed of the motor can be controlled by controlling the pulse frequency to attain speed control.

Why should we use the stepper motor?

The stepper motor can be divided into two stages, including unipolar and bipolar. The unipolar stepper motor includes public power supplies connected with all coils, but the bipolar stepper motor possesses the separated coils. The stepper motor is a brushless direct current motor with many internal teeth. These teeth are magnetically locked with the surrounded copper coils in a suitable position. Powering on the stepper motor will not make it rotate but lock it at a designated location by the given import and rotate a small step clockwise or counterclockwise.

Although it makes the stepper motor driving more complicated, compared to the brushless direct current motor, it possesses a main strength that it can pretty accurately ensure the angular position. For example, we would like to rotate the motor with an accurate angle of 270°. Then, the ordinary direct current brushless motor (without some formal feedback) almost can not do this, and the stepper motor can easily realize.

The stepper motor requires many stepper pulses to reach the desired position. And frequent powering on the stepper motor coil increases the holding torque greatly, but forced rotation is pretty hard. These strengths are illustrated why the stepper motor is used in many applications, including the CNC machine, semi-conductor, FPD, the manufacturing equipment of solar battery plate, and other motors.

Conclusion

The nema stepper motor only performs one step at a time, and each step is the same size. Each pulse will make the motor rotate at an accurate angle. Therefore, there is no need for any feedback mechanism to control the motor's position.

 

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