The invention belongs to the field of the control of a brushless direct-current motor, and particularly relates to a
delay control method for inhibiting
torque ripple of a brushless direct-current motor. The method comprises the steps: detecting the circulation situation of each phase of current, and determining an off-phase, a conducting phase and a non-commutation phase subsequently needing the phase changing; enabling the off-phase to be maintained on in the
delay time before the phase changing, maintaining the conducting phase off, and carrying out the
pulse width modulation for the non-commutation phase; carrying out the phase changing after the
delay is ended, turning off the off-phase, carrying out the flow-current by virtue of a
diode connected to opposing bridge arms in parallel, enabling the conducting phase and the non-commutation phase to be normally switched on, enabling the time that the current of the off-phase is decreased to 0 to be equal to the time that the current of the conducting phase is increased to a stable value, inhibiting the current fluctuation of the non-commutation phase, and inhibiting the phase-changing
torque ripple. A delay control time module is additionally arranged in an original
control system, a formula for calculating the
delay time is provided, the
adverse effect caused by the trial-error
delay time can be avoided, and the phase-changing
torque ripple can be rapidly and effectively inhibited.