What exactly does brushless mean?

[michaeld]

I'm a noob to the r/c scene and I have seen brushless a lot. What is it and why is it good?

[Adanmtxt1]

In a conventional brushed motor, there is a shaft passing through the motor can onto which there are lobes. On each lobe there are strands of wire wrapped about. If it is a 10-turn double, a strand of wire is wrapped around each lobe ten times, twice. Then there are magnets inside the can that interact with the wire when it has a current running through it. The timing of the current is determined by when the motor BRUSHES come into contact with the segmented commutator, which is that ring of shiny metal with which the brushes rub against. The more current running through the motor, the faster it turns and more torque is exerted. Horsepower is determined by RPM and torque.

In a brushless motor, there are no brushes contacting a commutator; instead the speed controller is sent information from a sensor telling it where the armature is (its position). Then the speed controller compares that to where the user 'wants' it to be, i.e. how fast we want it to go. So, if we want zero throttle, it doesn't send any pulses of current. If we want some throttle, it sends pulses based on armature position and which segment of the armature needs to be energized. Essentially, it just continually monitors position and sends a jolt of current to the next logical segment of the armature.

[Adanmtxt1]

Oh, and it is good because there is no physical contact between parts except bushings or bearings, which leads in part to its efficiency. Also, this leads to less maintenance (sp?), greater run time, more power, and the ability to set different profiles. You can ask for unlimited rpm, or say only 35000, different power profiles, etc because it is all electronically controlled via ESC. In general it is more powerful, I think, than comparable brushed motors.

[eVaDeR85]

When it comes to the power curve given by each type, a brushless exerts all of its potential at any rpm whereas brushed motors usually have a sweet spot that they produce the most power. Brushless motors I have found exert the same amount of power it seems like at any throttle however they also have what I like to call the efficiency sweet spot because at a certain rpm and load brushless runs cooler and looses less energy in the form of heat but power is the same throughout the rpm range.

[Duster_360]

There's also a big maintenance diff between the two. Brushed motors need a lot of maintenace to run at peak performance. Sometimes, brushed motors need work just to get them to their peak, and more work to keep them there.

Brushless is nearly maintenance free compared to brushed.

I run electric only in 18th scale and here's the diff - my Vendetta, running a hotrod brushed motor (VR3), would give me peak speed for 4, maybe 5 minthen it would slow a little, but noticeably. The charge would last 12, maybe 15min tops. Now running brushless, its much faster and stays that way throughout almost all the batt charge. The same batts now give me 18-20min run time. Put a lipo batt in there and I have gotten 27-30min run times. Out of the 4 18th scales I have only one is still brushed and I have just got a brushless (tekin mini-rage 6800) set up for it.

[Neon_Dave]

What exactly does brushless mean?

Exactly what the name implies :D Brush*Less* - no brushes :D

This is a key difference - in brushed motor, the wire is winded around the stacks on the armature, and the magnets are in the can. The brushes contacting the commutator and current being fed through them in pulses generates the electromagnetism to turn the armature. In a brushless motor, it's the exact opposite. The the current is still fed to the windings in the motor to make that electromagnetism, but the difference is that these windings are located on the can, not the armature. The main magnets are located on the armature. Thus being able to turn the armature (and in turn power the car) without any physical contact (with the exception of the bearings/bushings, as Adam pointed out)

Generally brushless motors are more efficient, usually more powerful than their equivelant brushed counterparts, and run considerably cooler. They require next to no maintenance too :D They are also capable of keeping the same preformance for much longer periods of time than a brushed motor would. (For example, an equivelant high-powered, low turn (less windings), brushed vs. brushless motor, before the brushless motor collects a spec of dust the brushed motor requires a comm cut to restore it to that "peak" preformance, which will still not be as high of a "peak" as when you started.

So, you can see the advantages brushless motors offer due to that simple "opposite" design, and the advantages that the less friction/contact points offer as well.

Hope that clears up a few things :)
-Dave