Brushless DC Electric Motor

Brushless DC Electric Motor

Brushless DC motors (BLDC motors, BL motors) also known as electronically commutated motors (ECMs, EC motors) are synchronous motors which are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor (AC with a caveat – alternating current often implies a sinusoidal waveform; a better term would be bi-directional current with no restriction on waveform); additional sensors and electronics control the inverter output amplitude and waveform( and therefor percent of DC bus usage/efficiency) and frequency ( ie rotor speed ).

The motor part of a brushless motor is often a permanent magnet synchronous motor, but can also be a switched reluctance motor, or induction motor.

Brushless motors may be described as stepper motors; however, the term stepper motor tends to be used for motors that are designed specifically to be operated in a mode where they are frequently stopped with the rotor in a defined angular position. This page describes more general brushless motor principles, though there is overlap.

Two key performance parameters of brushless DC motors are the Motor constants Kv and Km ( which are numerically equal in SI units)