A conventional DC motor is a brushed DC motor, abbreviated as a flow motor. The DC gear motors
is the earliest electric motor. Among all the executive motors, the DC motor has the best working characteristics. Compared with other types of motors, DC motors are small in size, high in efficiency, high in output, large in starting torque, strong in overload capacity, good in dynamic characteristics, easy to control, flexible and convenient, so they are widely used in high-demand speed regulation and motors. In the position control system, it has dominated this field for nearly a hundred years.
With the advancement of science and technology, the DC motor itself has also developed rapidly, and there have been many varieties used in different fields, becoming the fastest-growing and most-changing motor. Has the following characteristics.
Using permanent magnets to replace the excitation windings For a long time, the excitation of DC motors was realized by the electric excitation of the excitation windings. However, in the 1960s, especially since the 1980s, the development of permanent magnet materials has been very rapid, the performance has been greatly improved, and the price has been reduced. Permanent magnet excitation is widely used in small and medium-sized executive DC motors. After the permanent magnet replaces the electric excitation winding, in addition to the good characteristics of the electric excitation type DC motor, it also has the advantages of power saving, copper saving, no excitation loss, high efficiency, small size and simple structure.
New structures and new types of DC motors In order to meet the technical requirements in different fields, new types of DC motors are constantly being developed, with a wide variety and different characteristics. Such as fast response printed winding armature motor, wire wound armature motor, slotless armature motor, cup armature motor, disc motor, high inertia DC motor suitable for servo drive, suitable for direct drive and removal of reduction gears The torque motor, as well as the DC motor that produces linear motion, etc. All of these types of motors perform unique roles in different applications.
Due to its excellent performance, brushless DC motors have been widely used in various fields. In the field of electric traction, they have obtained an indisputable dominant position in the application of power conversion or execution of motion commands. The main reason why the DC motor has excellent working performance is that it has a commutator composed of brushes and commutators, which realizes the smooth transformation and regulation between the internal and external currents of the motor brushes, that is, the direct current of the external circuit is commutated through the commutation. The inverter converts and inverts it into alternating current on the armature winding, thereby completing the conversion process from electrical energy to mechanical energy. It is precisely because of the high-speed sliding contact between the brushes and the commutator that the electrical conduction is conducted, which leads to a series of fatal shortcomings of the yu motor. Including: unreliable contact, many failures, short life, need to be maintained by the party, sparks during commutation will also cause interference to adjacent radio equipment, etc. However, the good performance of the DC motor makes it irreplaceable. People try to maintain the excellent performance of the DC motor, but also remove a series of shortcomings caused by the brush and the commutator, so the DC brushless motor has been developed. It is precisely because of the breakthrough of control theory and the development of power electronic devices and electronic technology that the brushless DC motor can be realized.