2020-09-27
| The brushed DC motor uses mechanical commutation, the magnetic poles are not used, and the coil rotates. When the micro DC motor is working, the coil will drive the commutator to rotate. The current direction change on the coil is caused by the friction between the brush and the commutator. Finished, the brush and commutator will generate friction and cause loss. Generally, the service life is only a few hundred hours, which is not enough for products that require continuous operation. Large-scale brushed DC motors need to replace the carbon brushes regularly. The brushless DC motor solves this difficulty by adopting electronic commutation. The coil of the micro DC motor is not moving, and the magnetic poles rotate. Electronic commutation is to sense the position of the magnetic poles of the permanent magnet through the Hall sensor, and to ensure that the direction of the magnetic force generated is correct by sensing the direction of the current in the coil in real time, thereby driving the micro DC motor. The speed control method of brushed DC motor and brushless DC motor is different. Brushed DC motor speed control is very simple, while brushless DC motor is more complicated. The principle of speed regulation is to control the voltage, but the brushless micro DC motor uses electronic commutation, so digital control is required, so it is more complicated. During the speed regulation process, the power supply voltage of the micro DC motor is constant. Change the control signal of the ESC, and then change the speed of the MOS tube through the microprocessor to change the speed. This is called variable frequency speed regulation. The brushed micro DC motor is commutated by the brush, and can be controlled by the analog circuit of the thyristor drive. It is very simple. Just adjust the power supply voltage of the micro DC motor to adjust the speed. The voltage and current pass through the commutator. Brush conversion changes the strength of the electrode's magnetic field, thereby changing the speed, which is called variable voltage speed regulation. |
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