1. Synchronous motors are mostly used in large generators, while asynchronous motors are almost entirely used in electric airports. Synchronous motor can flexibly adjust the voltage and current phase of input side, that is, power factor, and the power factor of asynchronous motor can not be adjusted, which is generally between 0.75 and 0.85, so in some large factories, when asynchronous motor is widely used, a synchronous motor can be added as adjusting camera to adjust the power factor at the interface between factory and power grid. However, due to the high cost of synchronous motor and heavy maintenance workload, capacitance compensation power factor is generally used.

2. The efficiency of synchronous motor is slightly higher than that of asynchronous motor. When the motor above 2000KW is selected, it is generally necessary to consider whether to choose synchronous motor or not. However, because the synchronous machine has excitation winding and sliding ring, it is necessary for the operator to control the excitation at a higher level. In addition, compared with the maintenance-free maintenance of asynchronous motor, the maintenance workload is larger. Therefore, most of the motors below 2500KW choose asynchronous motor. When the power is small, the difference in efficiency has become insignificant.