Stepper Motors vs. BLDC Motors: Differences & Uses

Sinotech    December 16, 2013

When you need a motor for an application, you may not know if a brushless DC motor or stepper motor is best. In principle, both types are permanent-magnet synchronous motors. The difference is in their specific characteristics and mode of operation.

BLDC Motors

Brushless DC motors are highly reliable and efficient, and have a high power-to-volume ratio. This high-power motor can deliver large amounts of torque over a range of speeds. BLDC motors are electronically commutated constantly changing the waveforms being delivered to a wound stator.   Brushless motors with an outer rotor tend to operate at lower speeds  and have high output torque.. Those with an inner rotor  have lower rotor inertia and therefore higher output speed.

Advantages of BLDC motors include: responsiveness, quick acceleration, reliability, long life spans, high speed operation and a high power density. You can find brushless DC motors in applications like medical equipment, cooling fans, cordless power tools, turntables and automation equipment.

Stepper Motors

Stepper motors are brushless DC motors that divide a full rotation into a number of equal steps. Instead of continuously rotating, a step motor rotates in stepped angles.  Hybrid stepper motors have a magnet-bearing shaft that’s surrounded by an electromagnetic stator . When it’s energized, the stator aligns itself with the rotor and rotates the motor. The motor makes small movements, or steps, that keep it positioned accurately and synchronized with the magnetic field produced. Stepper motor varieties include:  permanent magnet stepper, variable reluctance stepper hybrid stepper, and permanent magnet stepper

Advantages of a step motor include: reliability, accuracy, quick acceleration, responsiveness, open loop control and positioning stability. You can find stepper motors in high-precision applications like CD drives, flatbed scanners, printers and plotters.

Depending on the application, you may find that a step motor or brushless motor is appropriate for the job, as is the case with servo drives. To learn which type of motor is best for your application, contact Sinotech.

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