Comparison of the application of induction motors, permanent magnet motors and servo motors in different fields

Induction motor

Working principle: Induction motor works on the principle of electromagnetic induction. The stator winding is fed with alternating current to generate a rotating magnetic field, and the rotor conductor cuts the magnetic lines of force to generate an induced current, which in turn generates an electromagnetic force to drive the rotor to rotate.

Advantages: Simple structure, high reliability, low cost, no excitation required, and easy maintenance.

Disadvantages: Small starting torque, difficult to adjust the speed, and relatively low efficiency.

Application: Widely used in fans, water pumps, compressors and other equipment.

Permanent magnet motor

Working principle: Permanent magnet motor uses permanent magnets to generate a magnetic field. The stator winding is fed with alternating current to generate a rotating magnetic field, which interacts with the magnetic field of the rotor permanent magnet to generate torque and drive the rotor to rotate.

Advantages: High efficiency, high power density, large torque, fast response speed, and high control accuracy.

Disadvantages: Permanent magnet materials are expensive and sensitive to temperature.

Application: Widely used in servo systems, electric vehicles, new energy power generation and other fields.

Servo motor

Working principle: The servo motor is a closed-loop controlled motor that precisely controls the motor through position, speed or torque feedback signals.

Features: Fast response speed, high precision, and precise position and speed control.

Classification: According to the rotor structure, it can be divided into AC servo motor and DC servo motor. Among them, the most common AC servo motor is the permanent magnet synchronous servo motor.

Application: Widely used in CNC machine tools, robots, automated production lines and other occasions that require high-precision control.

Detailed explanation of performance indicators

Efficiency: The efficiency of permanent magnet motors and servo motors is generally higher than that of induction motors. This is because permanent magnet motors use permanent magnets to generate magnetic fields, reducing excitation losses, while servo motors use closed-loop control to optimize the working state of the motor.

Power density: The power density of permanent magnet motors and servo motors is higher, which means that they can output more power at the same volume.

Torque: The starting torque of permanent magnet motors and servo motors is large, while the starting torque of induction motors is relatively small. Servo motors can also achieve high-precision torque output through precise control.

Speed ​​regulation: Induction motors require a frequency converter to achieve a wide range of speed regulation, while permanent magnet motors and servo motors have a wide speed regulation range.

Control accuracy: Servo motors use closed-loop control to achieve very high control accuracy, while induction motors and permanent magnet motors have relatively low control accuracy.

Cost: Induction motors have the lowest cost, while permanent magnet motors have a higher cost because of the high cost of permanent magnet materials. Servo motors are also relatively expensive due to their complex control systems.

Reliability: All three motors have high reliability.

Maintenance: Induction motors have the simplest maintenance, while permanent magnet motors and servo motors have relatively complex maintenance because of their more complex internal structures.

Which motor to choose depends mainly on your application requirements.

If you are sensitive to cost and do not have high performance requirements, you can choose an induction motor.

If you need high efficiency, high power density and a wide speed regulation range, you can choose a permanent magnet motor.

If you need high-precision position and speed control, you can choose a servo motor.