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What are Brushless DC motors

Ryan XieMarch 10, 2023

What is a Brushless DC Motor?

A brushless DC motor (Brushless DC motor) is a motor that uses a brushless converter to achieve synchronous rotation between the rotor magnetic field and the stator magnetic field.

BLDC motor consists of three parts: stator, rotor and electronic controller. Several coils with the same number of phases are wound on the stator, and the electronic controller outputs timing signals to the coils on the stator, so that the magnetic field between the coils changes continuously with time, thereby driving the rotor to rotate.

Structure of Brushless DC Motor

There are some differences in the structural design of brushless DC motors from traditional brushed DC motors. The structure of BLDC motor generally includes three parts: rotor, stator and electronic controller.

Rotor: The rotors of BLDC motors generally use permanent magnet materials, such as NdFeB, SmCo, etc. The number of poles of the permanent magnets on the rotor is usually equal to the number of coils of the stator to achieve synchronous rotation. In rotor design, the shape and field distribution of the permanent magnets also need to be considered to meet the specific needs of the motor.

Stator: The stator of a BLDC motor usually employs multi-phase windings to achieve high efficiency and high power density of the motor. In the stator design, factors such as the number, shape, size and layout of the coils need to be considered to achieve the best electromagnetic performance.

Electronic controller : The electronic controller of the BLDC motor usually uses a special chip or module to realize the control of the rotor. In controller design, factors such as control algorithm, power supply circuit, and drive circuit need to be considered to achieve efficient control and drive.

Diffenrences Between Brush DC Motor

Compared with brushed DC motors, the structural design of BLDC motors has the following differences:

Brushless converter: The rotor of the BLDC motor does not need carbon brushes and commutators to change the direction of rotation, but uses an electronic controller to control the timing signal to realize the alternate work of the coils on the stator, thereby realizing the synchronous rotation of the rotor .

Permanent magnet rotor: The rotor of a BLDC motor generally uses permanent magnet materials to improve the power density and efficiency of the motor.

Multi-phase windings: The stator of a BLDC motor usually employs multi-phase windings to improve the efficiency and power density of the motor.

Brushless Converter
Brushless Converter
Multi-phase Windings
Multi-phase Windings

What are the advantages of Brushless DC motors ?

The main advantages of BLDC motors over traditional brushed DC motors are:

BLDC motors do not need to use brushes and commutators, reducing mechanical friction and energy loss, so higher efficiency can be achieved.

Better speed-torque characteristics: Brushless motors no longer lose output torque due to contact friction of the brushed structure.
High dynamic response: Because the rotor of the brushless motor is composed of permanent magnets, it can have a lower moment of inertia.
Long operating life: Brushless motors do not need to consider the subsequent maintenance of the brush commutation structure
Lower electronic noise: There is no electromagnetic interference problem caused by electronic signal noise generated by the arc during brush commutation.
Higher speed range: Brushless motors do not have the limitations of brush commutation contact parts
● Improved motor characteristics: Since brushless motors use electronic commutation, circuit technology can be used to improve commutation behavior.

Applications for BLDC Motors

Brushless DC motors (BLDC motors) have the advantages of high efficiency, high reliability, low noise, and long life, so they have excellent performance in many application fields. The following are some common application areas:

Automotive– Electric Vehicles (EVs)- Hybrid Electric Vehicles (HEVs)- Electric Power Steering (EPS)- Braking Systems- Cooling Fans
Industrial Automation– Automated Machinery (robotic arms, conveyors, etc.)- CNC Machine Tools
Home Appliances– Home Cleaning Devices (cordless vacuums, robotic cleaners, etc.)- Kitchen Appliances (food processors, mixers, etc.)
Aerospace– Unmanned Aerial Vehicles (UAVs)- Satellite Positioning Systems
Medical Equipment– Portable Medical Devices (ventilators, blood circulation aids, etc.)- Medical Diagnostic Equipment (MRI machine rotors)
Consumer Electronics– Personal Care Products (electric toothbrushes, electric shavers, etc.)- Camera Stabilizers
Renewable Energy– Wind Power Generation (blade angle adjustment)- Solar Tracking Systems (angle adjustment for solar panels)
Leisure & Entertainment– Electric Toys (remote-controlled cars, model airplanes, etc.)- Fitness Equipment (treadmills, ellipticals, etc.)
Application of BLDC Motor

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