Delay control method for inhibiting torque ripple of brushless direct-current motor

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.