Asynchronous, Brushless DC, Stepper Motors and Permanent Magnet Synchronous Speed ​​(Servo) Motors Compare Other Motors Permanent Magnet Synchronous Speed ​​(Servo) Motors
different
step
Electricity
Machine Power Factor Low Power Factor High
Excitation current component is required to establish main flux Without current excitation, the permanent magnet establishes the main flux
Low efficiency, no energy saving, high efficiency, energy saving
Low torque coefficient, large current torque, low current
There is a slip, the relationship between speed and frequency is not fixed No slip, the relationship between speed and frequency is relatively fixed
Rotor is squirrel-cage type or wound type Rotor with built-in magnet or surface-bonded magnet
The price is slightly higher
The biggest problem of the synchronous motor is that it cannot be started directly. In the speed control system, due to the application of the frequency converter, the synchronous motor starting problem is naturally solved, and its superiority is fully reflected.
Brushless DC Back-EMF is square wave or trapezoidal wave Back-EMF is sine wave
High harmonic amplitude, high power pollution, high sub-harmonic amplitude, and almost no pollution to the power supply
Torque ripple Large torque ripple
Low-speed operation is not smooth Low-speed operation is stable
Stepper motor rotates in steps, large torque ripple, continuous rotation, small torque ripple
Low-speed operation is not smooth, low-speed operation is stable
Speed ​​increase torque drop 0~ n N is constant torque, n N ~1.5 n N is constant power
Low control accuracy, poor overload capacity, slow response speed, high control accuracy, high overload capacity, fast response
Open loop operation, no feedback Select closed loop or open loop as needed
The structure is simpler, the drive system is simple, and the price is low. The structure and drive system are more complex than the stepper motor and the price is slightly higher.