What are “brushless” tools and why are they (seemingly) better?


What are “brushless” tools and why are they (seemingly) better?

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Brushless tools have no brushes on the motor, so less moving parts and it’s a failure point. Less moving parts, less failure. “Seemingly better”

There are a couple of different kinds of motors, but let’s focus on brushed and brushless motors.

On a brushed motor, you’ll have carbon “brushes” that connect to the motor to provide electricity to the electronic magnet coils in the center of the motor (the windings) to push against permanent magnets attached to the outside of the motor (the can). The amount of torque and power are limited by how much energy can be transferred through the brushes before they start arcing and burn up the brushes or the surface they ride on (the com). The amount of turns the windings have determine how much power you can get (less winding, more power), but the more power you have, the quicker you burn up your brushes and com (Due to arcing). Some motors are serviceable, like hobby grade RC car motors, and low turn motors would be serviced as often as the race rules would allow. High turn motors would be used on non race applications so you could get a season or two before it needs to be serviced. The advantage to brushed motors is that you can run them without a controller, simply by adding power via a switch or variable resistor. The motor switches the magnetic poles based on rotor position and what side of the com the brushes are on.

Brushless motors are built a little different and require a controller. The most common are three and four pole motors. The center of the motor is a permanent motor. They can will house three or more electromagnets. The controller will flip the magnetic fields as required to control motor speed. The entire process removes the brushes for a contactless way to power the motor. You gain another point or two of magnetic power while freeing up power loss cause now you don’t have springs and brushes pushing against the com. You can add sensors so the controller can know where the rotor is for smoother start up and better low speed performance. This allowed hobby grade cars to hit triple digit speeds with motors that could last until the bearings go out, and those are serviceable in some applications. Less resistance also means longer run times and cooler batteries (under the same rpm and load).

So the advantages are more power capacity, no sparks, and a much longer service life and efficiency.