How does a brushless DC motor work: Why do you need a drive circuit?
To rotate the motor, the direction of current flowing through the motor windings (coils) must be alternated in order to generate a rotating magnetic field. For brushed DC motors, this is achieved through the mechanical action of brushes and commutators. So, how does a brushless DC motor without these components generate a rotating magnetic field and rotate?
Instead of replacing commutators and brushes, brushless DC motors use semiconductor switches. Brushless DC motors usually have three coils, and each switch is connected to a semiconductor switch. Turning on and off the semiconductor switches in the correct sequence will alternately generate current, which will generate a rotating magnetic field, which will cause the motor to rotate. Therefore, the motor needs a drive circuit to perform the sequencing. In addition, the semiconductor switch is switched by detecting the direction of the permanent magnet rotor using a magnetic sensor (usually a Hall sensor).
Outer and inner rotor motors
Brushless DC motors can be roughly divided into outer rotor motors and inner rotor motors.
Outer rotor motor
These motors have coils inside and magnets outside, so it is the outer circumference of the motor that rotates. Although this configuration means that the moment of inertia of the rotor is high, it helps maintain stable rotation.
Inner rotor motor
These motors have a magnet as a rotor inside and a coil as a stator outside. The advantage of this internal rotor configuration is that the rotor has a small moment of inertia and can be precisely controlled.
Understand how the brushless DC motor works when in use
Brushless DC motors are motors that do not require consumable brushes and commutators. They benefit from quiet operation, long life and low maintenance costs.
Instead of brushes and commutators, a drive circuit is used to electronically drive a brushless DC motor. The drive circuit is required to turn on and off the semiconductor switches in the correct order to generate a rotating magnetic field that causes the motor to rotate.
We hope the information provided here is useful to you.