1 DC motor DC motors are motors that operate on DC oper […]
1 DC motor
DC motors are motors that operate on DC operating voltage and are widely used in tape recorders, video recorders, video players, electric razors, hair dryers, electronic watches, and toys.
1.1 Brushless DC Motor
Brushless DC motors use semiconductor switching devices to achieve electronic commutation, that is, electronic switching devices replace traditional contact commutators and brushes. It has the advantages of high reliability, no commutation sparks, low mechanical noise, etc. It is widely used in high-grade recording seats, video recorders, electronic instruments and automation office equipment. Brushless DC motors consist of permanent magnet rotors, multipole winding stators, position sensors, etc.
Position sensing changes the current of the stator windings in a certain order according to the change of the rotor position (that is, the position of the rotor pole relative to the stator winding is detected, and the position sensing signal is generated at the determined position, and is processed by the signal conversion circuit. To control the power switch circuit, according to a certain logic relationship winding current switching).
The operating voltage of the stator winding is provided by an electronic switch circuit controlled by the position sensor output. Position sensors are magnetic, photoelectric and electromagnetic types. A brushless DC motor using a magnetically sensitive position sensor has a magnetic sensor element (such as a Hall element, a magneto-sensitive diode, a magnetically sensitive diode, a magneto-resistor, or an application-specific integrated circuit) mounted on a stator assembly. To detect changes in the magnetic field generated by permanent magnets and rotors. A brushless DC motor adopting a photoelectric position sensor has a photoelectric sensor arranged at a certain position on a stator assembly. A shading plate is mounted on the rotor, and the light source is a light emitting diode or a small light bulb. When the rotor rotates, due to the role of the shading plate, the photosensitive components on the stator will generate pulse signals intermittently at a certain frequency.
A brushless DC motor adopting an electromagnetic position sensor is equipped with an electromagnetic sensor section (such as a coupling transformer, a proximity switch, an LC resonant circuit, etc.) on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will make the electromagnetic sensor. Generates a high frequency modulated signal (its amplitude varies with rotor position).