As the stator is stationary and integral with the housing, cooling can be done primarily through conduction, and no additional forced air circulation is required to cool the motor. Typically, BLDC motors where the stator is surrounded by the rotor (outrunners) have higher torque values at low speeds. In any case, it is the permanent magnet rotor that moves with respect to the stationary winding part. In practice, star connection is the most common in the case of BLDC motors, as it is more efficient in typical applications.īrushless DC electric motors come in three varieties: the stator is surrounded by the rotor (outrunners), the rotor is surrounded by the stator (inrunners), or the rotor and stator are flat and parallel (axial). The delta connection system provides less torque at low speeds but achieves a higher maximum speed than star connection. The windings can also be star-connected, where their ends are connected at a central point while power is supplied to the remaining end of each winding. Three-phase motors can be connected in a delta configuration, where the end of each winding is connected to the beginning of the next, and power is supplied to each of the three points created in this way. If the electromagnetic fields produced by the stator windings and rotor magnets are misaligned, a torque develops that sets the rotor in motion. The switching of current through successive windings is carried out by means of semiconductor elements such as transistors. Instead, they are electronically commutated - a special controller adapted for use with BLDC motors switches current through the stator windings producing magnetic fields which smoothly rotate in space and which the permanent magnet (usually a powerful neodymium magnet) rotor follows. The biggest difference between the two types of motors is the lack of a commutator, a rotary switch that supplies power to the rotor windings, in BLDC motors. BLDC motor structureīrushless motors have a different structure compared to commutator motors. BLDC motors, thanks to their undoubted advantages, are used in an increasing number of devices, ranging from computer components such as optical drives and cooling fans, through hand-held power tools, toys, and remotely controlled vehicles, e.g., drones, household appliances, to machines and devices for transport and movement, including scooters, bicycles, and electric cars.
Electric motors, including the increasingly popular BLDC motors, also known as brushless motors or synchronous DC motors, are devices used to convert energy electricity to mechanical energy, most often in the form of rotational motion.