Brushless DC motor (BLDC)

A brushless DC motor is a DC motor that has thrown away its mechanical brushes and replaced them with electronics. In a brushed motor, a sliding commutator switches the current to keep the rotor pushed in the right direction; a BLDC instead puts permanent magnets on the rotor and electromagnet coils on the stator, and a controller electronically switches those coils on and off in sequence — energising whichever coil will pull the magnet around next. The magnetic 'whirlpool' is steered by transistors, not carbon contacts.

Removing the brushes removes their wear, sparking, and noise, so a BLDC runs cleaner, cooler, longer, and more efficiently — which is why they power drones, computer fans, electric bikes, and many EV traction motors. The catch is that the controller must know exactly where the rotor is at every instant, sensed by Hall-effect sensors or inferred from the back-EMF; get the timing wrong and the motor stutters or stalls. A BLDC is, in truth, a small permanent-magnet synchronous machine driven by its own electronics.