With the development of power electronics, micro electronics technology and AC motor speed control and control technology, many DC generators have been replaced by various thyristor rectifier power supply. DC motor and DC drive system in some areas, especially in the field of large motor, is running, maintenance is relatively easy to exchange speed motor and AC speed control system, the application scope is reduced.
However, the DC motor and the DC transmission system can be decoupled by long-term development, and accumulated a wealth of experience in operation and maintenance. Taking into account the AC adjustable speed motor and AC speed regulation system. In a certain capacity range and some operation modes, there are still some problems in the technical and economic rationality of the system, some operation requirements and running environment are also the direct current system. Therefore, in a certain period of time, DC motor and DC drive system and the development of space, can not be completely replaced.
In the face of reality, the current development trend of DC motor is to adopt new technology, new structure, new materials, new technology, and overcome the new problems in the commutation, insulation, noise and vibration caused by the power supply of the motor. On this basis, to meet the special requirements of different machinery, improve and develop the maintenance, testing system, and fully play the inherent characteristics of the DC motor, with the matching of the thyristor rectifier power system, design, manufacture a new series of DC motor.
To do this, the following aspects of the DC motor to do a lot of work, and achieved results:
1) to improve the design and manufacturing level of DC motor. The analysis of magnetic field, commutation, mechanical stress, vibration and ventilation cooling is carried out by using electronic computer and numerical analysis technology. The new structure, new technology and new material are used in the combination. It can improve the rated voltage level of electric motor, increase the rated voltage level of motor, increase the ratio of core length and diameter of rotor, improve the insulation performance of the motor, and improve the reliability of H, F class insulation and advanced insulation structure and vacuum pressure (VPI) technology to improve the reliability of electric contact.
2) the new structure is developed by using new materials. Active promotion of new rare earth permanent magnet materials to small and medium-sized motor; vigorously develop new structure: such as the use of polygonal stator yoke stator yoke, and the main interpole core adopts laminated structure (even the small motor stator yoke and main interpole core make one), in order to improve the utilization of space within the stator and armature meet rate the current rapidly changing requirements; small motor foot set on the front and back cover, increase the foot bearing surface, to reduce motor vibration; improvement of bearing structure, the corresponding amplification bearing and motor shaft diameter, in order to adapt to the output torque of the rotor increases; with high strength banding process as much as possible. No wedge, some large motor armature coil wire using the variable section, in order to reduce the armature high, improving commutation and heating parameters; using special commutator structure, in order to improve the work As the speed, reduce the amount of copper; development of various cooling methods, and in the small motor rotor core is also set up the radial ventilation groove, to improve the heat dissipation condition...
3) to improve and develop the maintenance inspection system. The structure is complex, the difficulty of detection and maintenance work is big, it is one of the main reasons that restrict the development of DC motor. Using advanced motor condition monitoring technology, from local monitoring to system monitoring, development of fault diagnosis and expert evaluation system, fault trend analysis, in order to simplify and reduce maintenance work, to ensure reliable operation of motor.