Motor brief said: synchronous and asynchronous motor, ac motor is on ac power supply and rolling. Asynchronous motor stator into alternating current (ac), is in a rotating magnetic field, and the rotor by induction magnetic field, the two magnetic field effect, makes the rotor with the stator's rotating magnetic field and rolling. The rotor is slower than the stator rotating magnetic field, there is a slip, sync so called asynchronous machine. With induction motor and synchronous motor stator, the rotor is artificial join dc constant magnetic field, so that the rotor to synchronize with the stator rotating magnetic field, called synchronous motor. Brief asynchronous motor, the cost is low. Easy to install, use and maintenance. So was used. Faults low power, low power factor of power grids. And synchronous motor power is a capacitive load, can improve the power factor of power grid. Multi-purpose mining large not ready. 1, structure: synchronous motor and induction motor stator winding is the same, the main difference is that the structure of the rotor. Dc field winding of synchronous motor rotor, so demand plus excitation source, after a slip ring is introduced into current; And asynchronous motor rotor winding is short circuit, by electromagnetic induction current. Synchronous motor, by contrast, more complex, the cost. 2, use: synchronous machine is mostly used in the occasion of large generators. While the asynchronous motor can full use in motor. Synchronous motor can be recuperated after excitation sensitive input side of the phase voltage and current, power factor namely; The power factor of asynchronous motor is adjustable, so in some large factories, application of asynchronous motor is large, can be added a synchronous motor for condenser, used to regulate the factory and the power factor of power network interface. But, because the cost of synchronous motor, maintenance work, now generally choose capacitance compensation power factor. In addition, some preliminary selection of thyristor inverter, because without the ability to shut off the device, change demand depends on the load flow, then needs to use synchronous motor. 3, effectiveness: synchronous motor power is asynchronous motor is a bit, usually want to consider whether to choose synchronous motor. Synchronous machine, however, because of the exciting winding and the slip ring, demand for operators has the level to control excitation, in addition, compared to the induction motor of free maintenance, maintenance work; So, now mostly choose the asynchronous motor. The power is small, power difference has become negligible.
