The speed difference between DC and AC fans

Generally speaking, the speed of DC fans and AC fans is different because of their different design and control methods.
DC fans are usually driven by motors and have flexible speed control. The speed of the DC fan can be changed by adjusting the voltage or current, or different speeds can be achieved using PWM (Pulse Width Modulation) controllers. However, some advanced AC fans can use special controllers to achieve variable speed functions, but these AC fans are usually more expensive. The speed of a DC fan can also be influenced by factors such as its power supply voltage, motor load, number and length of blades, and blade shape.
In contrast, AC fans typically use AC power, and their speed is usually determined by the design and manufacturing of their motors. The frequency and voltage provided by the AC power supply will directly affect the speed of the AC fan. Generally, it is not possible to directly control the speed of the AC fan by changing the voltage or frequency of the power supply. If you want to adjust the speed of the AC fan, you need to use a specialized speed control device, such as a frequency converter or a speed control motor.
The frequency converter can adjust the speed of the AC fan by changing the frequency of the AC power supply. This is achieved by converting AC power into DC power, and then using an AC motor frequency converter to convert the current into a specific frequency of AC power. This method requires the use of additional speed control devices and circuits, and the cost is relatively high.
Another method of adjusting the speed of an AC fan is to use a variable speed motor. This type of motor uses electronic circuits to control the speed of the motor, so the speed of the AC fan can be adjusted. However, variable speed motors are more expensive than traditional AC motors, so not all AC fans can use variable speed motors.
Summary: Although the speed of AC fans is different from that of DC fans, they can be used for many similar applications, such as ventilation, heat dissipation, and air conditioning systems. But their working principles and control methods are different. Generally speaking, the speed of an AC fan is difficult to adjust as easily as a DC fan.