What The Tech: How does an elec­tron­i­cally commu­tated EC motor work?

What are the differ­ences between an elec­tric motor with an alter­nating current (AC motor) and an elec­tron­i­cally commu­tated EC motor and what are the advan­tages?

Until now, hand-oper­ated elec­tric tools were mainly oper­ated with so-called AC series motors. These motors have good load behavior, but they do have prob­lems, too: they can easily over­heat and due to the wear of the carbon brushes need a lot of main­te­nance work. This is different for EC motors, as alter­nating voltage is recti­fied in the commu­ta­tion elec­tronics.

But what does that mean? The stator, that is the stationary part of the motor, contains the wind­ings. The moving rotor contains perma­nent magnets with alter­nating poles. When the wind­ings are ener­gized according to the desired speed and direc­tion of rota­tion, the rotor starts to rotate. The under­lying commu­ta­tion works as follows: Phase 1 is ener­gized in such a way that the same polarity is produced as on the applied rotor magnet. Phase 2, on the other hand, is ener­gized to the nega­tive pole. The repul­sion of iden­tical and attrac­tion of different poles starts the rota­tion. The nega­tive pole is now trans­ferred from phase 2 to phase 3. The motor then continues to operate in this way.

As a result, an EC motor has a very high level of effi­ciency. This means that hardly any power is lost in the form of heat. In general, the motor hardly develops any heat, saves energy and is less expen­sive due to the elim­i­na­tion of main­te­nance work over its service life. It is also 25 percent lighter than AC motors with the same power. And it also runs very quietly. But best of all, it works as a plug & play solu­tion and does not require a trans­former control unit, a vari­able frequency drive, or a motor protec­tion switch, for example. Never­the­less, it can operate in a broad and easily control­lable speed range. Doesn’t that sound convincing?

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