1. High efficiency

　　The high efficiency mentioned here does not only mean that the efficiency at the rated power point is higher than that of ordinary three-phase asynchronous frequency modulation motors, but refers to its average efficiency in the entire speed regulation range. The excitation magnetic field of the permanent magnet synchronous motor is provided by permanent magnets, and the rotor does not need excitation current, so the motor efficiency is improved. Compared with asynchronous variable frequency speed regulation, it saves energy at any speed point, and this advantage is particularly obvious when the speed is low.

　　2. Small starting current and large starting torque

　　According to the characteristics of the frequency converter, during low-frequency starting, the main magnetic field of the asynchronous variable-frequency speed-regulating motor is low, the power factor is low, and although the starting current is large, the starting torque is very small; the main magnetic field of the rare earth permanent magnet synchronous variable-frequency speed-regulating motor is constant, the stator current is almost all active current, the starting current is small, and the starting torque is large.

　　3. Good strength index

　　The power energy index of a motor refers to the product of the motor efficiency and the power factor. When the asynchronous variable-frequency speed-regulating motor works under load, its efficiency, power factor and power energy index decrease. The efficiency and power factor of the rare earth permanent magnet variable-frequency motor are approximately a horizontal curve. Even when the motor is only loaded, the power energy index of the rare earth permanent magnet motor is still above full load, which further improves the efficiency of electric energy use and the quality factor of the power grid.

　　4. Small size, heavy basin and light weight

　　Due to the use of high-performance permanent magnet materials to provide the magnetic field, the air gap magnetic field of the permanent magnet motor is greatly enhanced compared to the induction motor, and the size and weight of the permanent magnet motor can be greatly reduced compared to the induction motor.

　　Based on the above comparative advantages, at present, permanent magnet synchronous motor is the best choice for variable frequency drive motor, which is more efficient and energy-saving than ordinary three-phase asynchronous variable frequency motor!