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The difference between AC motors and brushless DC motors

DC motors and AC motors are two major categories of motors. Discussions about these two motors have been ongoing. Today we will discuss these two motors.

I often see friends asking online whether brushless DC motors or AC motors are better to use. In fact, there are many differences between the two. Which one is better? Let's first take a look at the differences between the two!

The structure of the motor is different

In AC motors, there is a coil with a relatively small resistance, typically around 100 ohms. Taking a split-phase motor as an example, it is divided into a starting winding and a running winding.

The internal structure of a brushless DC motor mainly consists of a stator and a rotor. In the past, most motors used brushed motors, which are still used by some people today, but they require slightly more maintenance. Due to the development and design of brushless DC motors, they have a smaller size compared to AC motors and brushed DC motors. Therefore, much industrial equipment has now switched to DC brushless motors.

Different working principles

The power supply voltage of the AC motor is alternating current, and the motor can be controlled on and off using AC switch components. For a brushless DC motor, its power supply voltage is DC input, which can be controlled through PWM technology. A PWM is a signal with an adjustable duty cycle that can input different signals. DC can achieve stepless speed regulation, adjust the speed level to a high level, and add feedback signals, closed-loop speed regulation, and braking functions. In other words, it can quickly stop within a certain time range and have better output stability.

Different output power

Generally, the power of brushless DC motors is lower than that of AC motors, especially brushless DC motors. Brushless DC motors overcome many of the disadvantages of brushed motors. Therefore, in the current motor market, brushless DC motors are more popular than brushed DC motors.


From the above, it can be seen that whether a brushless DC motor or an AC motor is better depends mainly on one's own needs. It is important to first understand their respective characteristics and choose the appropriate motor in order to bring more convenience to one's production and life.

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