AC induction motor is a kind of electrical energy into mechanical energy, electrical actuator. It mainly consists of a stator, a rotor air gap between them and composition. Leading to the stator winding phase AC power, the rotor generates a rotating magnetic field and cut to obtain the torque. Three-phase AC induction motor has a simple structure, reliable operation, cheap, strong overload and the use, installation, maintenance and convenient features, the most critical is that it has the following outstanding advantages:

     a) AC induction generator is simple and reliable. Because it does not need to produce a wound rotor current, and it is therefore not required nor brushes maintenance. It is self-motivation structure, the output sine wave completely. Even if only a single phase electrical equipment, we are always output three-phase AC generator.

     b) synchronous AC generator with or without a brush, but it must be a need for wound rotor excited, but there must be an overload circuit breaker to protect it. Brushless type required by the diode to produce excitation current. All these have increased the complexity of the generator and the possibility of failure.

     c) Single-phase asynchronous alternator output phase output of the 2/3, and a single-phase synchronous AC generator, the output of the three-phase output 1/3.

     d) Asynchronous alternator can drive such as heaters, incandescent resistive loads. But also for the power inverter welders and welding of polyethylene, etc. It is better than the capacitive device for synchronous AC generator, because these devices require a smooth sine wave voltage.

     e) Asynchronous alternator can withstand a short circuit will not be damaged, there is no need to spend money to install a circuit breaker or fuse to protect the welder. A short circuit will cause the generator excitation and does not lose power. Once the short is removed, the generator would not had any problems like the same back to work. On the other hand, for example, starting the motors have a large starting current of the device case, this advantage has become a disadvantage because the asynchronous alternator, this large startup currents like overload, the generator will stopping power, making it impossible to start the motor