Friends who use brushless motors are familiar with position sensors. So what is the role of the position sensor? They don't necessarily know. In the brushless motor, it measures the rotor pole position and provides the correct commutation information for the logic switch circuit, that is, the conversion position information, also referred to as the inductive brushless motor. The rotor poles are bitten into electrical signals, and then the stator windings are controlled to commutate. There are many types of position sensors, each with its own characteristics. There are three types of position sensors commonly used in brushless motor manufacturers: electromagnetic position sensors, magnetic position proximity sensors and photoelectric position sensors.
(1) In brushless DC motors, split transformers are widely used in electromagnetic position sensors. The open-circuit transformer of a three-phase brushless motor consists of a stator and a tracking rotor. The stator usually has six magnetic poles, and the interval between them is 60 degrees. Three poles are wound around the primary winding, connected in series, and connected to a high-frequency power supply. The remaining three poles are respectively wound with secondary windings wa, wb, and wc.
(2) Magneto-sensitive position sensor is a semiconductor sensor whose electrical parameters change with the surrounding magnetic field according to a certain rule. The basic principles are the Hall effect and the magnetoresistance effect. Commonly used magnetic sensors include Hall elements or Hall integrated circuits, magnetoresistive and magnetoresistive diodes.
(3) The photoelectric position sensor is a photoelectric device sensitive to the position of the light spot on the incident photosensitive surface, and its output signal is related to the position of the light spot on the photosensitive surface. It is a photoelectric position sensitive detector based on the lateral photoelectric effect. In addition to the positioning performance of the photodiode array and ccd, it also has the characteristics of high sensitivity, high resolution, fast response speed and simple circuit configuration.
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