Position-free sensor brushless DC motor rotor position compensation method

The invention relates to a position-free sensor brushless DC motor rotor position compensation method. The relation between two major factors (load size and filter delay) affecting the position detection precision of a rotor and a phase delay angle is analyzed, then the relation is processed to form a linear equation in two unknowns by use of a mathematic fitting mode, and finally rotor position compensation is carried out relevantly according to the equation. According to the invention, the phase conversion precision of a motor is improved, the torque ripple is reduced, the motor efficiency is enhanced, and out-of-step faults caused by severe lagging of phases are avoided.