In recent years, the permanent magnet motor has attracted the most attention in the motor industry, and the degree of popularity has shown an increasing trend. The reason why permanent magnet motors have attracted much attention is inseparable from the strong support of relevant Chinese policies. High-efficiency and ultra-high-efficiency motor products represented by high-efficiency permanent magnet motors can be quickly popularized, helping energy conservation and emission reduction, and retaining green mountains and green waters. Energy saving and environmental protection must be the future development trend, especially in the motor industry. The energy saving characteristics of permanent magnet motors show its advantages. Its energy saving rate can be higher than 20%. The advantages of energy saving of rare earth permanent magnet motors are as follows:
1. Compared with ordinary motors, permanent magnet motors can save energy by 20-40%, and the specific equipment working conditions vary in power saving rate.
2. The permanent magnet synchronous motor reaches the first-level energy efficiency, and the energy efficiency is above 95%; the ordinary three-phase asynchronous motor has the third-level energy efficiency, and the energy efficiency is only about 90%.
3. The rotor of the permanent magnet synchronous motor has rare earth permanent magnet steel, which does not need the stator to provide induction electricity, and the loss is smaller than that of ordinary motors;
4. The stator leads of permanent magnet synchronous motors are star-shaped (Y) connected, which can keep the power constant and the current small; most ordinary motors use △ connection;
5. During the operation of the permanent magnet synchronous motor, the energy efficiency value can remain unchanged when the load changes. The energy efficiency value of the ordinary asynchronous motor will change when the load changes. The value remains the same, when the load is less than 70%, its energy efficiency value will drop linearly.
6. The no-load current of the permanent magnet synchronous motor is small, only reaching one-tenth of the rated current, while the current of the ordinary asynchronous motor reaches one-third of the no-load.
7. The rare earth permanent magnet motor adopts high-performance permanent magnets, which saves the current excitation of the stator or rotor part of the motor, so the copper loss (heating loss of the winding) of this part is saved;
8. The mechanical loss of the brushless structure and the carbon brushless structure is adopted, but the brushless motor realizes the commutation through the electronic commutation structure. Here, there is a loss of some electronic components, which is compared with the saved mechanical loss. The value is small, so the loss of the commutation part is smaller than that of the brushed motor;
9. Using high-performance rare earth permanent magnets, under the same rated power and rated speed, the volume of the motor can be made smaller, which saves the silicon steel sheet of the motor and reduces a part of the iron loss. Rare earth permanent magnet motors for low-power motors can achieve an efficiency close to 90%, and General Motors are only about 75%.