A permanent Magnet Synchronous AC motor is a new type of motor with the advantage of high efficiency and energy-saving.

It can be divided into two categories, VFD (variable frequency drive) synchronous ac motor and asynchronous start synchronous ac motor. The common feature is the rotor magnet steel structure; the difference is that there is no aluminum ring on VFD synchronous ac motor to help it start automatically, only can start with the help of VFD and the motor speed can be adjusted by VFD. But there is an aluminum ring on the rotor of the asynchronous start synchronous ac motor, so this kind of motor can start automatically without an inverter. The character is the rotor rotating together with a magnetic field at a constant speed. Under the power of 50Hz, the rotation speed of the 2-pole motor is 3000rpm; the 4-pole is 1500rpm. Its speed will not be changed according to the load or voltage like an asynchronous motor and the speed will be a little lower than the rotational speed of magnetic field.