A DC brushless rotary motor is an electrical motor that runs on direct current electricity without brushes and commutator, produces rotary motion or torque and converts electrical energy into mechanical energy.
After the development of semiconductor electronics in the 1970s, the brushes and commutator in the brushed motor could be eliminated, an electronic control system replaces the mechanical commutator contacts. Brushless DC motors (BLDC motors), also known as electronically commutated motors (ECM or EC motors) and synchronous DC motors, powered by DC electricity via an inverter or switching power supply. In a typical brushless DC motor, the permanent magnets are fixed on the rotor and the wound armature (electromagnet coils) become windings of the stator. The speed of the rotor is affected by the speed of the rotating magnetic field of the stator and the number of poles.
The Hall effect sensor is used to perceive the position of permanent magnet pole, for timely switching the direction of current to ensure that the magnetic force is generated in the right direction. But on the market today, there are still many BLDC rotary motors take advantage of back electromotive force instead of using Hall effect sensors.