Online detection method for open-circuit faults of power tubes of induction-motor vector control system

The invention discloses an online detection method for open-circuit faults of power tubes of an induction-motor vector control. The online detection method includes steps of respectively measuring three-phase current and revolving speed by a current sensor and a speed sensor existing in the vector control driving system; calculating d-axis current and q-axis current of a directed synchronous revolving coordinate system of a rotor flux link through coordinate transformation; reconstituting a-phase current phase angle by replacing an initial angle during fault by an initial angle during normal operating, and dividing the reconstituted current phase angle into six stages; comparing the detected d-axis current and the d-axis current with the given d-axis current and q-axis current to obtain current bias Eid and Eiq; subjecting the bias Eid to continuous accumulation summation and detecting whether the open-circuit faults exist or not; subjecting the bias Eiq to continuous accumulation summation to obtain hopping