Accurate commutation control method for position-sensing-free brushless direct current motor

The invention discloses an accurate commutation control method for a position-sensing-free brushless direct current motor. The method comprises the following steps that S1, a timing value of a timer module is used for calculating the speed of a motor rotor to complete a timing function; s2, the A/D module samples motor end voltage and phase current and then converts the motor end voltage and the phase current into corresponding line values for rotor position calculation; s3, the PWM module obtains a commutation logic signal according to the detected rotor position signal, sends out a corresponding driving signal, and controls motor commutation to realize a control function on the commutation driving signal; within a certain period of time, the counter value of the counter potential zero crossing point number is divided by the number of poles to obtain the rotating speed of the motor, and the ideal no-load rotating speed point of the motor can be flexibly adjusted. When the motor is under the load condition, t