Stepper motors are widely used in various applications that require precise control of motion. They are available in two main types: unipolar and bipolar stepper motors. These motors differ in their construction and operation, and it is important to be able to identify which type of motor you are working with in order to select the appropriate driver circuit and to properly control the motor. In this article, we will discuss how to identify unipolar and bipolar stepper motors.

Construction of Unipolar and Bipolar Stepper Motors

Unipolar stepper motors have two sets of coils, one set of which is connected to the positive supply voltage and the other set is connected to the negative supply voltage. The coils are arranged in such a way that there is a common center tap between them. This center tap is connected to the motor's common ground.

Bipolar stepper motors also have two sets of coils, but each coil is connected to its own set of wires. In other words, there is no center tap, and the motor does not have a common ground.

Identifying Unipolar Stepper Motors

To identify a unipolar stepper motor, you can look for the center tap or the common ground connection between the coils. Unipolar stepper motors typically have six wires, with two wires for each coil and a common ground wire. The common ground wire is usually connected to a metal plate on the motor or a separate wire that is connected to the motor's housing.

Another way to identify a unipolar stepper motor is to use a multimeter to test the resistance between the wires. If the resistance between the wires is roughly equal, then the motor is likely a unipolar stepper motor.

Identifying Bipolar Stepper Motors

To identify a bipolar stepper motor, you can look for the absence of a center tap or a common ground connection between the coils. Bipolar stepper motors typically have four wires, with one wire for each coil. The wires are usually labeled A, A', B, and B', with A and A' connected to one coil and B and B' connected to the other coil.

Another way to identify a bipolar stepper motor is to use a multimeter to test the resistance between the wires. If the resistance between the wires shows two sets of roughly equal resistance, then the motor is likely a bipolar stepper motor.

Conclusion

In conclusion, identifying unipolar and bipolar stepper motors is important in order to select the appropriate driver circuit and to properly control the motor. Unipolar stepper motors have a center tap or a common ground connection between the coils and typically have six wires, while bipolar stepper motors do not have a center tap or a common ground connection and typically have four wires. By understanding the construction and operation of these two types of stepper motors, you can properly identify and control them for optimal performance.