Structure of BLDC motor

A brushless DC motor (BLDC) is a type of synchronous motor where the magnetic fields of the stator and rotor operate in harmony at the same frequency. BLDC motors use an electronic commutator, allowing for smooth and efficient motion. They are popular due to their high output power, low electrical noise, exceptional reliability, rapid dynamic response, minimal electromagnetic interference, and excellent speed-torque performance. These characteristics make BLDC motors crucial for high-performance applications, including electric vehicles, industrial automation, and medical devices.

The high output power of BLDC motors meets the demands of heavy-duty equipment, while low electrical noise contributes to quieter operation. Their reliability supports stable, consistent performance, and their quick responsiveness allows for easy adjustment to changing conditions. Additionally, reduced electromagnetic interference lessens disruptions to surrounding electronic systems, and improved speed-torque traits enhance efficiency across varying load scenarios.

Though there are several types of brushless DC motors with diverse designs, they fundamentally consist of three main components: a rotor, a stator, and a motor control unit. The rotor typically contains permanent magnets, while the stator consists of coil windings and iron cores. The motor control unit includes phase detection and commutation elements, along with the brushless motor controller.

The rotor can be categorized into two types: outer rotor and inner rotor. It may feature multi-pole block magnets or ring magnets, while the stator houses the windings. Position detection elements, often Hall effect sensors, are installed on the stator to work with the controller, facilitating the motor's commutation. Despite the inclusion of electronic commutation, the structure of a brushless DC motor is relatively simple, making it comparable to that of an AC synchronous motor.

The figure below illustrates the inner rotor structure of a brushless DC motor. This type of motor is widely used across various fields. For instance, in devices with strict space constraints, the inner rotor brushless DC motor is particularly suited to meet design requirements. Additionally, its relatively simple structure provides certain advantages in terms of manufacturing and maintenance.