Knowledge of brushed motors
In a brushed motor, it contains a brush device that converts electrical energy into mechanical energy, or mechanical energy into electrical energy. The brushed motor is the foundation of all motors, and has the advantages of fast starting, timely braking, smooth speed regulation in a large range, and relatively simple control circuit.
The brushed motor is mainly composed of a stator and a rotor. There are magnetic poles (windings or permanent magnets) on the stator, and windings on the rotor. After adding electricity, a magnetic field (magnetic pole) will also be generated on the rotor. In the stator magnetic field (N and S) Under the action of the motor, the motor rotates. By changing the position of the brush, the angle of the magnetic poles of the stator and the rotor can be changed (it is assumed that the direction of the magnetic pole of the rotor toward the magnetic pole of the stator is the rotation direction of the motor), and the rotation direction of the motor can be changed.
A special point to note here is that the brushed motor is powered by direct current, so it is generally called a brushed motor and is also called a "DC motor".
Knowledge of brushless motors
The brushless motor is composed of the motor body and the driver. Since the brushless motor operates in an automatic control mode, it is not necessary to use the variable frequency speed regulation method for the heavy-load starter motor to attach a starting winding to the rotor, and it will not cause oscillation or vibration due to sudden changes in the load. out of step.
Brushless motors use semiconductor switching devices to achieve electronic commutation, that is, use electronic switching devices to replace traditional contact commutators and brushes. The brushless motor is composed of a permanent magnet rotor, a multi-pole winding stator, a position sensor, etc. The position sensor commutates the stator winding current in a certain order according to the change of the rotor position (that is, detects the position of the rotor magnetic pole relative to the stator winding, and generates position detection The power switch circuit is controlled by the signal conversion circuit, and the winding current is switched according to a certain logical relationship). The operating voltage of the stator windings is provided by an electronic switching circuit controlled by the output of the position sensor.
The brushless motor has high reliability, no commutation sparks, and low mechanical noise, and is widely used in high-end video recorders, video recorders, electronic instruments and automated office equipment. A special point to note here is that many people think that a brushless motor is a DC motor, so it is called a "brushless DC motor". In fact, a brushless motor is an AC motor, which is a three-phase AC permanent magnet motor.
