The difference between brushless motor and AC speed regulating motor

Release Time：

2024-10-28

Brushless motors and AC speed regulating motors are two common types of motors, and their main differences are reflected in their working principles, structural design, performance characteristics, and application fields.

1、 Working principle

The brushless motor is powered by a DC power supply, and the current is controlled by a shaft encoder and an electric control chip, so that the permanent magnets and coils inside the brushless motor always maintain a fixed electromagnetic deflection angle. During operation, the motor can achieve steering and speed regulation by changing the polarity and magnitude of the current.

AC speed regulating motors are powered by AC power and achieve speed regulation by changing the frequency of the power supply. Usually, a frequency converter is used to change the frequency of the power supply in order to control the speed of the motor.

2、 Structural Design

The internal structure of brushless motors is relatively simple, mainly composed of permanent magnets, rotors, and drive circuits. Among them, permanent magnets are usually made of permanent magnet materials, which have high magnetic permeability and magnetic energy product. The rotor is fixed with permanent magnet material, which generates electromagnetic force through external current and drives the rotor to rotate.

3、 Performance characteristics

1. Speed regulation range: Brushless motors have a wide speed regulation range, which can achieve lower speeds while having high torque accuracy. The speed range of AC speed regulating motors is relatively narrow, generally around ± 30% of the rated speed.

2. Efficiency: The efficiency of brushless motors is relatively high, usually above 90%, while the efficiency of AC speed regulating motors is affected by power frequency and speed, generally around 80%.

3. Response speed: Brushless motors have fast response speed, short starting time, and the speed can reach over 90% of the rated speed. The response speed of AC speed regulating motors is relatively slow and the starting time is long.

4. Maintenance cost: Due to its brushless structure, brushless motors do not require regular brush replacement, resulting in lower maintenance costs. AC speed regulating motors require regular replacement of brushes, resulting in higher maintenance costs.

5. Noise: Brushless motors have low noise and minimal vibration; The AC speed regulating motor has high noise and vibration.

The internal structure of AC speed regulating motors is complex, usually consisting of a rotor, stator, and drive circuit. Among them, there is no fixed permanent magnet suspended on the rotor, but a traditional electromagnetic structure is used. There are multiple sets of coils on the stator, which generate a magnetic field through AC power supply to drive the rotor to rotate.