Anyone who uses brushless motors is no stranger to position sensors. So what is the role of the position sensor? What is the principle?

The position sensor plays a role in determining the position of the rotor magnetic pole in the brushless motor, and provides the correct commutation information for the logic switch circuit, that is, the position signal of the rotor magnetic steel pole is converted into an electrical signal, and then the commutation of the stator winding is controlled. There are many types of position sensors, and each has its own characteristics. There are three types of position sensors commonly used in brushless DC motors: electromagnetic position sensors, magnetic-sensitive position proximity sensors, and photoelectric position sensors.

(1) The open transformer is the most used electromagnetic position sensor in the DC brushless motor. The split transformer used in the three-phase brushless DC motor is composed of a stator and a tracking rotor. The stator generally has six poles, with an interval of 60 degrees between them. Three poles are wound with a primary winding and connected in series with each other to be connected to a high-frequency power supply. The other three poles are respectively wound with secondary windings WA, WB, and WB. WC.

Magnetic Sensitive

(2) Magnetic-sensitive position sensor refers to a semiconductor sensitive element whose electrical parameters change with the surrounding magnetic field according to a certain rule. The basic principles are Hall effect and magnetoresistance effect. Common magnetic sensors include Hall element or Hall integrated circuit, magnetoresistor and magnetoresistive diode.

Photoelectric

(3) The photoelectric position sensor is made of photoelectric effect, and it is composed of a light shield that rotates with the motor rotor, a fixed light source, a photoelectric tube and other components.

Brushless motors are high-tech products that integrate motors, microelectronics, control, and computers. Brushless motors are widely used in high-precision control industries such as medical, industrial control, automotive electronics and consumer electronics