Brushed or brushless – RC motor dilemma

You want to fly, you need a motor. Electric, internal combustion, jet, ion, gravity. It does not matter. And since gravity engines are not invented yet, ion has no place in atmosphere and jet or internal combustion are kind of non-practical for multirotors usage, we have to stick with electric motors.

Brushed DC motors

In RC world there are two types of DC motors we can choose from: brushed and brushless. The brushed ones are wth us for decades. Cheap and proven, but with a few downsides. First of all, they have brushes and brushes wears off because of friction. After time, they stop to conduict electricity and has to be replaced. Plus, they cause sparks, lowers efficiency, make noise, are sensitive to dust and so on… This is why, we do not use brushed DC motors any more.

Brushless BLDC motors and ESC

 

Instead, we are using brushless (BLDC) DC motors. The main difference is that (what a surprise) they does not have brushes. They even does not have anything like a commutator you’ve might remember from physics lessons. They are only a set of magnets and electric coils connected into 3-phase setup. This is why BLDC motors has 3 wires instead of 2! And since they do not have a bult-in device that changes the flow of electric current, they will not spin by them own. They need a specialized drivers called ESC (Electronic Speed Controller). ESC is responsible for switching electric current flow into engine itself very, very quickly and thus make motor to spin. It actually converts DC into 3-phase AC according to given input signal.

Brushless RC motor on quadcopter frame

As you can imagine, this sounds quite complicated. And it is. Although, comparing to brushed brother, brushless motors are far less complicated and more reliable on a mechanical level, they, as a set with ESC, are way more complicated on electrical/electronics level. Actually, each ESC has it’s own microcontroller, n-FET transistors, firmware and so on. And, as a set, they are more expensive. But… But in total, they are more effective, more reliable, harder to break, easier to control and just better.

So, when thinking about motors for multirotor build, or any RC in that matter, think brushless. Maybe slightly more expensive, but on a longer run, way, way better.

Leave a Reply

Your email address will not be published.