Deciding Between Unipolar or Bipolar Stepper Motors?
If you're working on a project or product that requires precise control of rotational movements or positional accuracies, stepper motors might be exactly what you need. One of the most common questions people ask when thinking about stepper motors is whether unipolar or bipolar motors are better. In this article, we'll compare the pros and cons of unipolar and bipolar stepper motors to help you decide which type of motor you should use.
The difference between Unipolar vs Bipolar Stepper Motors
Before getting into the pros and cons, let’s first understand the difference between unipolar and bipolar stepper motors.
Unipolar Stepper Motors
Unipolar stepper motors have two sets of windings per phase, with each winding having a center tap. When current flows through the winding, it will create a magnetic field that can interact with the permanent magnet installed on the rotor, resulting in rotational motion. To change the direction of motion, the current direction on one of the coils needs to be reversed.
Bipolar Stepper Motors
In contrast, bipolar stepper motors only have one winding per phase. But this winding has a center tap, allowing for a reverse current flow through the same winding, resulting in magnetic field polarity changes that can generate rotational movements.
Pros and Cons of Unipolar vs Bipolar Stepper Motors
Now that we have a clear understanding of the difference between the two types of stepper motors, let's take a look at how they compare when it comes to different factors.
Step Resolution
Bipolar stepper motors provide higher step resolution and therefore offer better positional accuracy. Bipolar motors require twice the number of winding leads but provide double the torque in bipolar half-step drive mode.
Torque and Speed
Unipolar stepper motors are typically more accessible, simpler to control, and offer more torque at lower speeds. Bipolar stepper motors are generally faster and offer more torque at higher speeds.
Complexity and Cost
Unipolar stepper motors are less complex and, therefore, easier and less expensive to control. In contrast, bipolar stepper motors can be more complex to operate and require more precise control electronics.
Overall Versatility
Both unipolar and bipolar stepper motors have different advantages when it comes to versatility. If you're looking to achieve high levels of positional accuracy and increased torque, bipolar stepper motors are ideal. However, if you're looking for a more straightforward and cost-effective solution with adequate accuracy, unipolar stepper motors may be the better option.
Conclusion
After considering the pros and cons of each type of stepper motor, it's clear that choosing between unipolar and bipolar motors depends on the specific use case, the desired level of precision and torque, and the available budget. So, always take the time to consider all of your options to make the right decision.