High Quality Content by WIKIPEDIA articles! Brushless DC electric motor (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 ).