Until recently, there were two types of compact fans, those in AC alternating current and those in DC direct current. Then, the EC electronically commutated fans appeared. Let’s start by distinguishing the different types of fans through the type of power supply used.
AC alternating current fans
The AC fans work with the alternating voltage and have an operating range linked to the standard mains voltages such as 230 Vac or 115 Vac and allow a 10% variation of supply voltage.
DC direct current fans
DC fans use direct voltage instead: the direct current is widely used at low voltage in electronics. The most common voltage values in the electrical panels are 12 Vdc and 24 Vdc, in some particular applications are also used the voltages of 48 Vdc and 5 Vdc. Generally, these fans, comparing same sizing, have better performance than those in AC and similar to those EC.
EC electronically commutated fans
EC fans use AC voltage too, but they can have a wider voltage range. They are available in the classic versions of 115 Vac and 230 Vac, but also in the “multivoltage” versions that accept a supply voltage from 90 to 266 Vac, while maintaining the same performance throughout the arc of supplied voltages.
Comparison between AC, DC and EC fans
At a functional level, the AC fans use asynchronous motors (induction motor) while the DC and EC fans use synchronous motors (brushless). The difference between the two types is given by the rotor: in the synchronous motor DC + EC the rotor consists of permanent magnets, while in the AC asynchronous motor the magnetization takes place at the expense of the electric power supplied to the motor, with a higher consumption of energy.
This is one of the reasons why EC fans, with the same performance, consume less power than an AC fan of the same size, and are more silent.
Therefore, it’s correct to imagine the EC fan as a hybrid between an AC and a DC fan: from the first one it takes the characteristic of being able to be supplied with an alternating voltage, a feature extended by the possibilities provided by the multivoltage, from the second it takes the same internal technology, being equipped with a synchronous motor, and therefore the relative advantages as better performance and less absorption of electrical energy.