Brushless DC motor vs. stepper motor-What’s the difference？

With the powerful functions and decreasing costs of electronic components, the application of stepper motors and brushless DC motors is becoming more and more common. Although according to its structure and driving principle, the stepper motor is a special DC brushless motor, the stepper motor belongs to the control type motor, and there are many differences between them.

In terms of structure and construction:

1. The brushless motor can be an outer rotor or an inner rotor structure, but the stepper motor is an inner rotor structure.
2. The amount of magnets used in brushless motors is relatively large.
3. The rotor shaft of the brushless motor can be made of ordinary steel, while the rotor shaft of the stepper motor must be made of stainless steel or copper, which is a non-magnetic material.
4. In order to obtain better torque in stepper motors, the gap between rotor and stator is very small, while the gap between rotor and stator of brushless motor does not need to be so strict.
5. The brushless DC motor generally has a Hall to detect the rotor position of the motor to realize commutation (there is also a Hall without a Hall, and the rotor information is obtained by calculation), while the stepper motor operates according to one pulse, and generally does not need to detect the rotor.

Brushless DC motor

A brushless DC motor consists of a motor body and a driver and is a typical mechatronics product. Brushless motors are motors without brushes and commutators, also known as commutators motors. The brushless DC motor has the characteristics of excellent linear mechanical characteristics, a wide speed regulation range, large starting torque, a simple control method, electronic commutation instead of mechanical commutation, no wear, no spark, and greatly reduced noise.

Stepper motor

The Stepper motor can be used as a special motor for control and is widely used in various open-loop control because there is no accumulated error. Generally, the accuracy of the stepper motor is 3-5% of the step angle, and it does not accumulate. Stepper motor torque decreases as speed increases. The stepper motor can run normally at low speed, but if it is higher than a certain speed, it will not start, and it will be accompanied by a whistling sound.

Conclusion

When choosing motors such as stepper motors and brushless DC motors, you can compare the characteristics and performance of these two motors, and then decide which machine to choose according to the needs of users.