2. Development status
The development of permanent magnet synchronous motors is closely related to the development of permanent magnet materials. The emergence of new permanent magnet materials has greatly promoted the development of permanent magnet synchronous motors. In the 1980s, NdFeB rare earth permanent magnet materials were introduced. Due to the abundant resources of strontium, the expensive cobalt was replaced by cheap iron, and the price was relatively low. The magnetic properties of NdFeB rare earth permanent magnet materials have greatly promoted the development of permanent magnet synchronous motors.
2.1 Development results
China attaches great importance to the research and development of NdFeB permanent magnet motor and has included the national "863" research plan. After years of research and development, we have achieved fruitful results and developed five types of high-performance permanent magnet synchronous motor prototypes with 22 typical specifications.
1) Three kinds of high-efficiency, high-starting torque permanent magnet synchronous motor prototypes with typical specifications successfully solved the four contradictions of high mutual starting torque, good energy saving effect, high temperature without demagnetization and reasonable cost. Table 1 shows the performance comparison of a 37kW rare earth permanent magnet synchronous motor and an induction motor developed in China for oil field pumping units. Table 2 shows the performance comparison between the newly developed rare earth permanent magnet synchronous motor with 1120kW and the induction motor and electric excitation synchronous motor for fan and pump operation.
2) High-efficiency and high-induction synchronous NdFeB permanent magnet synchronous motor for chemical fiber machinery (6 specifications). Compared with the existing motor, the power factor, efficiency and maximum torque multiple of the developed motor have different degrees of improvement. The out-of-step torque is 3.59 times of the original and the traction torque is increased by 3 times.
3) The machine tool spindle uses 7.5kW high constant power speed regulation ratio NdFeB permanent magnet synchronous motor and drive system. The speed range of the developed permanent magnet synchronous motor speed control system is 0.4r/rain~9000r/min (the speed range of the spindle induction motor of the same specification in China is only 8r/min~8000r/re_in), constant power speed ratio Reached 1:6.
4) Permanent magnet synchronous motor and drive system for electric vehicles. The permanent magnet synchronous motor system for the 7.5kW light electric bus developed has a motor weight of 45kg, a magnet usage of 0.92kg, a rated speed of 3000r/min, and a maximum speed of 5500r/min. The overall rated efficiency of the prototype system is 89.1%, the continuous torque density of 1h is 0.74N•m/kg (air-cooled), and the continuous torque density of 15min is 1.123N•m/kg (Japan AISIMAW prototype, 1h continuous torque density is 0.78 N•m/kg) (oil-cooled) with a continuous torque density of 1.178 N•m/kg for 15 min.
5) High starting capacity NdFeB permanent magnet starter motor (4 specifications prototype). The developed motor replaced a part of the original permanent magnet pole with an inexpensive soft iron auxiliary magnetic pole, saving about 30% of the NdFeB permanent magnet material.
