What kind of sensors are used in a brushless DC motor?

There are a few different types of sensors that can be used in a brushless DC  motor, depending on the specific application and control requirements. Some of the most common sensors used in BLDC motors include:

Hall effect sensors: These are used to detect the position of the rotor and provide feedback to the electronic controller. Hall effect sensors can detect the magnetic field of the rotor and determine its position and speed.

Encoders: These are high-resolution sensors that provide precise feedback on the position and speed of the rotor. They can be used in applications that require very high precision and accuracy, such as robotics or CNC machines.

Resolver: This is a type of electromagnetic sensor that provides feedback on the position and speed of the rotor. It can operate in harsh environments and is often used in industrial applications.

Current sensors: These sensors measure the current flowing through the motor's windings and provide feedback on the torque produced by the motor. They can be used to monitor and control the motor's performance.

Overall, the choice of sensor will depend on the specific requirements of the application and the level of control and precision needed for optimal performance.