来源：http://www.jnmcd.com 发布时间：2019-03-27 浏览：次
DC brushless motor consists of synchronous motor and driver. This is a typical mechatronics product. The stator windings of synchronous motor are mostly composed of three-phase symmetrical star connection, which is very similar to three-phase asynchronous motor. On the other hand, the rotor is jammed by a magnetized permanent magnet. In order to detect the polarity of the motor rotor, the position sensor is installed in the motor. The driver consists of power electronic devices and integrated circuits.
Its function is to receive the start, stop and brake signals of the motor to control the start, stop and brake of the motor. Position sensor signals and forward and reverse signals are used to control the on/off of each power transistor of the inverter bridge to generate continuous torque; speed commands and speed response signals are used to control and regulate speed; maintenance and display are provided.
The rotor position detector installed on the motor shaft is an important part of the brushless DC motor. It confirms when each phase winding of the armature starts to turn on. Its function is equivalent to that of brushes in ordinary DC motors. Changing the time (phase) of the signal generated by the position detector is equivalent to changing the position of the brush in the space of the DC motor, which has a great influence on the characteristics of the brushless DC motor. There are many types of position detectors, usually including a set of fixed detection elements and a position signal generator rotating with the motor rotor.
In the position detector composed of Hall element, Hall element is the detection element, and the rotor pole of the motor itself is the position signal generator. In other configurations, such as electromagnetic induction, photoelectric and press-close switch, notch discs are often used as position signal triggers. For example, in the photoelectric type, the notch is used to make the phototube illuminate to produce signals; in the electromagnetic induction type, the gap is used to change the magnetic circuit of the open-circuit transformer, thereby generating electromotive force in the detection coil, etc.
In short, by modifying the AC frequency and waveform of the current wave input to the stator coil of the brushless motor, the coil winding constitutes the magnetic field rotating around the geometric axis of the motor. The magnetic field drives the permanent magnet steel on the rotor to rotate and the brushless motor to rotate. The performance of brushless motor is related to the number of magnetic steels, magnetic flux intensity of magnetic steels and input voltage of motor. It also has a lot to do with the control performance of brushless motor. Because the input is DC current, the current needs to be converted into three-phase AC by electronic governor. It also needs to accept the control signal of remote controller acceptor to control the speed of brushless motor to meet the definition of the application demand of the model. The idle speed of brushless motor is KV multiplied by the input voltage. This also explains why. The speed of inner rotor motor is higher than that of outer rotor brushless motor.
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