Unipolar Stepper Motor

Unipolar Stepper v/s Bipolar Stepper

Unipolar Stepper Motors utilise tapped coils, of which each side can be independently magnetized. Because the current running through each coil will be running in a different direction dependent on which side of the coil is magnetised, the polarity of each phase can be reversed without reversing the current of the entire circuit.

Both uni-polar and Bipolar steppers are used widely in projects. However, they have their own advantages and disadvantages from the application point of view. The advantage of a uni-polar motor is that we do not have to use a complex H bridge circuitry to control the stepper motor. Only a simple driver like ULN2003A will do the task satisfactorily. But, there is one disadvantage of uni-polar motors. The torque generated by them is quite less. This is because the current is flowing only through the half the winding. Hence they are used in low torque applications.