Scope of application
The position sensor is one of the three major parts of the brushless DC motor system, and it is also the main symbol that distinguishes it from the brush DC motor. Its function is to detect the position of the main rotor during the movement, convert the position signal of the magnetic steel pole of the rotor into an electrical signal, and provide the correct commutation information for the logic switch circuit to control their conduction and cut-off, and make the motor armature The current in the winding changes in order with the rotor position to form a stepped rotating magnetic field in the air gap, which drives the permanent magnet rotor to continuously rotate.
The brushless DC motor needs a position sensor to measure the position of the rotor. The motor controller receives the signal from the position sensor to allow the inverter to commutate and synchronize with the rotor to drive the motor to run continuously. Although the brushless DC motor can also detect the position of the rotor through the anti-induced electromotive force generated by the stator winding, without the position sensor, when the motor starts, the speed is too small, and the anti-induced electromotive force signal is too small to be detected.
Hall sensor chips that can be used as position sensors for brushless DC motors are divided into two types: switch type and lock type. For electric bicycle motors, both Hall sensor chips can be used to accurately measure the position of the rotor magnet. There is no difference in the performance of the brushless DC motor made with these two Hall sensor chips, including the output power, efficiency and torque of the motor, and it can be compatible with the same motor controller.
The application of the position sensor reduces the noise of the motor operation, improves the life and performance of the motor, and achieves the effect of reducing energy consumption at the same time. The application of position sensors undoubtedly provides a strong impetus to the development of the motor market.
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