Brushed DC Motor vs. Brushless DC Motor
DC motors are mainly divided into brushless DC motors and brushed DC motors.
Brushed DC motor
DC motor is famous for its good start-up performance and speed performance, in which brushed DC motors use mechanical commutator to make driving simple, see the model diagram shown in Figure 1.
The motor is mainly composed of a stator made of permanent magnetic material, a rotor (armature) wound with a coil winding, a commutator and a brush. As long as the brush A and B at both ends of a certain direct current, the motor commutator will automatically change the direction of the motor rotor magnetic field, so that DC motor rotor will continue to run.
It can be seen that commutators and brushes play an important role in the DC motor. Although it can simplify the structure of the motor controller, it has some shortcomings in itself:
- The structure is relatively complicated, increasing the manufacturing cost.
- Easily affected by the environment (such as dust, etc.), reducing the reliability of the work.
- Produce sparks when commutating, limiting the scope of use.
- Easy to damage, increasing the maintenance costs.
Brushless DC motor
Brushless DC (BLDC) motor model as shown in Figure 2 is transformed from Figure 1 model. It consists mainly of a rotor made of permanent magnet material, a stator with coil windings and a position sensor. Can be seen, it has much in common with the DC motor, the stator and rotor structure is almost (the original stator into a rotor, the rotor becomes a stator), the winding connection is basically the same. However, they have a clear structural difference: brushless DC motors do not have commutators and brushes in DC motors, but instead are position sensors. In this way, the motor structure is relatively simple, reducing the motor manufacturing and maintenance costs, but the brushless DC motor can not be automatically commutated (phase), the expense of the cost of the motor controller to improve (such as the same three-phase DC motor, there The driving axle of brushed DC motor needs 4 power tubes, and the drive axle of brushless DC motor needs 6 power tubes).
Figure 2 shows one of the low-power three-phase, star-connected, single-pair magnetic pole brushless DC motor, its stator, the rotor outside, the structure and the DC motor shown in Figure 1 is very similar. Another brushless DC motor structure and this just the opposite, its stator, the rotor, including the stator is composed of coil winding machine base, and the rotor is made of permanent magnetic materials.
ATO brushless DC motor has the following characteristics:
- The brushless DC motor has good external characteristics and can output large torque at a low speed, so that it can provide a large starting torque.
- Brushless DC motor has wide speed range, any speed can be operated under full power.
- Brushless DC motor has high efficiency, strong overload capacity, making an excellent performance in the drag system.
- Brushless DC motor has good regenerative braking effect because its rotor is a permanent magnet material, the brake motor can enter the generator state.
- Brushless DC motor has small size and high power density.
- Brushless DC motor does not have mechanical commutator, and is applied with fully enclosed structure that prevents dust from entering the motor, and is highly reliable.
- Brushless DC motor is simpler to operate than the asynchronous motor drive control.