Understanding the Principles of BLDC Motors and Controllers

BLDC motor controllers regulate the speed and torque of the motor, and they can also start, stop, and change the direction of rotation. To grasp the principles of how these controllers work, let’s begin with the construction of a brushless DC motor. Its primary components include:

  1. Rotor: Made of permanent magnets, often neodymium, and,
  2. Stator: Equipped with windings that generate a magnetic field when powered.

The magnets on the rotor and the windings on the stator facilitate the motor’s rotation. They attract each other with opposite poles and repel each other with the same poles. A similar process occurs in a brushed DC motor. The significant difference lies in how the current supplied to the wire windings is switched.

In a brushed DC motor, this is a mechanical process initiated by the commutator with brushes. In a BLDC motor, it occurs electronically through transistor switches. BLDC motor controller determine the rotor’s position either with sensors (such as Hall sensors) or sensorless methods. The sensors measure the rotor’s position and send this data to the controller. The controller receives the information and enables transistors to switch the current and supply power to the necessary stator winding at the right moment.

Types of BLDC Motors and Controllers

BLDC motors can be of two types based on the rotor’s arrangement:

  1. Inrunner: The rotor is inside, while the stator is outside the motor.
  2. Outrunner: The rotor is external, so the permanent magnets rotate around the stator along with the motor casing.

Inrunners have a lighter construction and better rotational speed due to their smaller rotating diameter. Conversely, outrunners have higher torque due to a longer arm and greater electromotive force applied to the rotor.

Three-phase brushless DC motors can have two different types of winding connections:

  1. Star Connection (Y): Windings meet at the center, forming a star.
  2. Delta Connection (Δ): Windings are connected in series, forming a triangle.

In the star configuration, the neutral wire is connected to ground. This can protect the motor from overvoltage and overload. The delta connection lacks a neutral, making it better suited for motors with balanced loads. However, each of these types can demonstrate effective performance depending on your requirements.

Understanding the principles behind BLDC motors and controllers is essential for optimizing their performance and integrating them into various applications efficiently. Whether it’s for industrial automation, robotics, or automotive systems, BLDC technology offers versatility, reliability, and precision in motion control.

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