In daily life, all kinds of small household appliances and electronic products need to be powered by micro-motor DC motors. Careful people will find that in addition to AC motors, the others are micro-DC motors, and most products use DC motors. Brushless micro DC motors, such as coffee machines, razors, facial cleansers, beauty devices, etc., are rarely used in brushless micro motors. Why?
We know that the brushless motor has high speed, low noise and long service life, while the brushless motor is slightly inferior to it. But the brushed micro DC motor can run as long as it is connected to DC power, and the control is very simple. It can be controlled only by increasing or decreasing the voltage. The brushless micro-DC motor needs additional circuits to operate, and the torque is small when running at low speeds. If the torque is required, a reducer needs to be added, which requires relatively high product design mechanisms and cost.
Brushless micro DC motors generally need three Hall sensors to operate, because the three windings of the micro motor are 120°. In order to measure the three positions of the corresponding rotor, three Hall sensors are needed. They are also mutual Distributed at 120°, in the wiring, a reverse Hall needs to be set in the middle of the two Halls, which can shorten the lead wire. You must know that the brushless DC motor does not have a brush device. The brush and commutator are replaced by Hall sensors. Therefore, it will have high efficiency, low noise, high reliability, frequency conversion speed regulation and long service life. Features of ultra-high speed.
Simply put, in order for a DC motor to operate, there must always be a certain angle between the magnetic field of the stator coil and the magnetic field of the permanent magnet of the rotor. The rotation process of the rotor (that is, the process of changing the direction of the magnetic field) is to make the two magnetic fields have an angle. After a certain degree, the direction of the magnetic field of the stator coil must be changed, and the three Halls can be used to know the direction of changing the stator magnetic field. In other words, the three Halls are the task of telling the controller when to change the current.
Therefore, most electronic products use brushed micro DC motors more. The start control method of brushless DC motors is too complicated. Unless it is a product with high parameter requirements, and brushed micro motors cannot be realized, it will be used. Brushless DC motor.
Post time: Jul-15-2021