A brief description of the advantages and uses of BLDC motors and the difference between them and DC motors

A BLDC motor (brushless DC motor) is a rotating motor with permanent magnets in the rotor and windings as part of the stator. The BLDC motor replaces the mechanical commutator on a brushed DC motor with an electric commutator, powered by a DC power supply through an integrated inverter/switching power supply, which generates an AC signal to drive the motor. BLDC motors have high efficiency as well as good operability and are widely used in various transmission industries and expect the low power consumption it brings.

DC Motor (Brushed Motor)

A coil is placed in a magnetic field, and by flowing current, the coil is repelled by the magnetic pole on one side while being attracted by the magnetic pole on the other side, and rotates continuously under this action. The current flowing backwards into the coil during rotation keeps it rotating. The commutator part of the motor is powered by the brushes, which are positioned above the commutator and move continuously with rotation. By changing the position of the brushes, the current direction can be changed. The commutator and brushes are indispensable structures for the rotation of DC motors.

BLDC motor

BrushLess" in BLDC motors means "brushless", which means that the brushes in DC motors (brushed motors) are not present. The role of brushes in DC motors is to energize the coils in the rotor through the commutator, but BLDC motors use permanent magnets for the rotor, and there are no coils in the rotor.

The DC motor (brushed motor) has a magnetic field created by a fixed permanent magnet that does not move, and rotates by controlling the magnetic field generated by the coil (rotor), and changes the number of rotations by changing the voltage; the rotor of the BLDC motor is a permanent magnet, and rotates by changing the direction of the magnetic field generated by the surrounding coil, and controls the rotation of the rotor by controlling the direction and magnitude of the current flowing to the coil.

Advantages of BLDC motors

BLDC motors have more than three coils on the stator, with two wires per coil, for a total of at least six lead wires in the motor. In fact, because it is internally wired, usually only three wires are needed, but still one more than the previously described DC motor (brushed motor), which does not move by connecting the positive and negative terminals of the battery. High efficiency, you can control the gyratory force (torque) always maintain the maximum, DC motor (brush motor) rotation during the maximum torque can only be maintained for a moment, can not always maintain the maximum. If DC motor (brushed motor) wants to get as much torque as BLDC motor, it can only increase its magnet, that's why even small BLDC motor can give out great power. Good control, BLDC motor can get the torque and rotation number you want without any difference, BLDC motor can feedback the target rotation number and torque precisely, and the heat and power consumption of the motor can be suppressed by precise control. If it is battery driven, it can prolong the driving time by well-controlled. Durable and low electrical noise. DC motor (brushed motor) will have loss due to the contact between brushes and commutator for a long time, and the contacted part will also generate sparks, especially when the gap of commutator touches the brushes, there will be huge sparks and noise. If you do not want to make noise during use, you will consider using BLDC motor.

Uses of BLDC motors

What is the general use of BLDC motor with high efficiency, various control and long life? They are often used in products that can make use of their high efficiency and long life, and are used continuously. For example, BLDC motors have recently been used in electric appliances and electric fans, and have succeeded in significantly reducing power consumption because of high efficiency. By changing the control system, a significant increase in the number of rotations has been achieved. The vacuum cleaner demonstrates the good control of BLDC motor. The hard disk, which is an important storage medium, also uses a BLDC motor for its rotating part. Since it is a motor that needs to run for a long time, durability is important. It also has the use of extremely suppressed power consumption, and high efficiency is also related to low power consumption.

Conclusion

Brushless motor has many advantages over brushed DC motor, including high torque to weight ratio, higher torque (higher efficiency), higher reliability, lower noise, longer life (brushless and commutator corrosion), elimination of ionizing sparks generated by commutator, and overall reduction of electromagnetic interference. Since the windings are supported by the housing, they can be cooled by conduction, eliminating the need for airflow inside the motor for cooling, which in turn means that the interior of the motor can be completely enclosed to prevent dust or other foreign objects from entering. BLDC motors will be more appropriate for small robots, in terms of force control. If stepper motors are used, a structure such as a robot wrist to be fixed in a certain position requires BLDC motors are also suitable for use in drones, especially those with multi-axis racks, as it is possible to control the flight attitude by changing the number of rotations of the propeller, so BLDC motors that can precisely control the rotation are advantageous.