Generally with three winding phases, brushless DC motors are electronically commutated. A simple way to drive these motors is to power two phases at a time, using hall sensors to know the rotor position, with a simple logic to allow optimal energizing of the phases as a function of rotor position. Another way is to use sensorless electronics, working with the zero-crossing criteria to determine rotor position and commutation cycle. This electronics format is well suited for constant speed applications as they are highly insensitive to hostile environments.