What are the advantages and disadvantages of synchronous motor and asynchronous motor?
Asynchronous motor application: motor, its power range from several to tens of thousands of kilowatts, is in the industries of national economy and People's Daily life, the most widely used motor power for a variety of mechanical equipment and household appliances. For example, the machine tool, small and medium rolling steel equipment, fan, pump, light industrial machinery, metallurgy and mining machinery, mostly adopt three-phase Asynchronous Motor (Asynchronous Motor). Electric fans, washing machines, refrigerators, air-conditioners and other household appliances are widely used in single-phase asynchronous motors. Asynchronous motors can also be used as generators for wind farms and small hydroelectric plants.
The stator winding of the n synchronous motor and asynchronous motor is the same, the main difference is the structure of the rotor. The rotor of synchronous motor has dc excitation winding, so it needs to be coupled with excitation power supply to introduce current through the slide ring. The rotor of the asynchronous motor is a short-circuit winding, which generates an electric current through the electromagnetic induction. In contrast, synchronous motor is more complicated and expensive. Use n synchronous motor is used mostly in large generator Settings. Asynchronous motors are used almost exclusively in motor situations. The synchronous motor can adjust the voltage and current phase of the input side by excitation, the power factor. The power factor of asynchronous motor is adjustable, generally between 0.75 to 0.85, so in some large factories, application of asynchronous motor is large, can be added a synchronous motor for condenser, used to adjust the plant and the power factor of power network interface.
Synchronous motors are typically used for generators, while asynchronous motors are generally used for motors. Asynchronous motors are suitable for situations where there is no need for large scale speed adjustment, and have self-priming capability, which is low cost. The drawback is that power factors always lag. Steady state run time is no different.
The advantages of asynchronous motors: asynchronous motor is a ac motor, which is not constant relative to the frequency of the power grid. Therefore, it has the advantages of simple structure, easy manufacturing, use and maintenance, reliable operation and low quality and low cost. Asynchronous motors have higher efficiency and better operation of the work, from no-load to full load within the scope of nearly constant speed operation, the majority of industrial and agricultural production to meet the mechanical transmission requirements. Induction motor faults: due to the speed of the asynchronous motor instead of a rotating magnetic field speed slip relationship to a certain extent, its control performance is poorer (except ac commutator motor). To request a broad and smooth speed range of transportation machinery, rolling mill, large machine tools, printing, dyeing and paper making machinery, etc., using dc motor is more economic and convenient.
However, due to the high cost of synchronous motor and large maintenance, the capacitance compensation power factor is now used. In addition, some early transducers with thyristor, because the device has no self-closing ability, need to rely on the load exchange, which requires the synchronous motor. N synchronous motor is slightly higher than asynchronous motor. When choosing type of motor in 2000KW, it is important to consider whether to use synchronous motor. Synchronous machine, however, because of the exciting winding and the slip ring, need operation workers have higher level to control excitation, in addition, compared to the induction motor of free maintenance, maintenance workload is bigger; So now the motors under 2500KW are now mostly asynchronous motors.
