Compared with traditional electric excitation motors, permanent magnet motors, especially rare earth permanent magnet motors, have the advantages of simple structure, reliable operation, small size, lightweight, small loss and high efficiency, and flexible and diverse shape and size of the motor. The application is extremely wide, covering almost all areas of aerospace, national defense, industrial and agricultural production, and daily life.
The permanent magnet synchronous motor has the following characteristics:
1. Rated efficiency is 2% to 5% higher than normal asynchronous motors;
2. The efficiency rises rapidly with the increase of the load. When the load changes within the range of 25% to 120%, it maintains high efficiency. The high-efficiency operating range is much higher than that of ordinary asynchronous motors. Light-load, variable-load, and full-load all have significant energy-saving effects;
3. Power factors up to 0.95 and above, no reactive compensation required;
4. The power factor is greatly improved. Compared with asynchronous motors, the running current is reduced by more than 10%. Due to the decrease in operating current and system losses, energy-saving effects of about 1% can be achieved.
5. Low-temperature rise, high power density: 20K lower than three-phase asynchronous motor temperature rise, design temperature rise is the same can be made into a smaller volume, saving more effective materials;
6. High starting torque and high overload capacity: according to requirements, it can be designed with high starting torque (3-5 times) and high overload capacity;
7. The variable frequency speed control system is used, which is better in dynamic response and better than that of asynchronous motors.
8. The installation dimensions are the same as the asynchronous motors currently widely used, and the design and selection are very convenient.
9. Due to the increase in power factor, the visual power of the power supply system transformer is greatly reduced, which improves the power supply capacity of the transformer, and can also greatly reduce the cost of the system cable (new project);
10. When the new project is built, all the drive systems use permanent magnet synchronous motors, the project investment is basically the same as the use of asynchronous motors, and the project can continue to obtain energy-saving benefits after the project is put into operation;
In the general industrial sector, the replacement of a low-voltage(380/660/1140V) high-efficiency asynchronous motor, system saves 5% to 30% energy, and replacing the high-voltage(6kV/10kV) high-efficiency asynchronous motor, the system saves 2% to 10%.
