Patent ID: 8541988

Claim:
A rotary electric machine with a rotatable rotor, the rotary electric machine comprising: at least two-phase stator windings; a rectifying unit including, for each of the at least two-phase stator windings, a pair of a high-side rectifying element and a low-side rectifying element, at least the low-side rectifying element including a switching element with a diode connected in parallel thereto, the rectifying unit being configured to rectify an alternating current voltage induced across each of the at least two-phase stator windings; a turn-on unit configured to monitor an output voltage of the rectifying unit, and turn on the switching element as the low-side rectifying element for at least one of the at least two-phase stator windings when the output voltage exceeds a first threshold voltage due to a load dump; and a turnoff unit configured to: monitor the output voltage of the rectifying unit; after the output voltage, which exceeded the first threshold voltage once, falls below a second threshold voltage, wait for turnoff of the switching element as the low-side rectifying element for the at least one of the at least two-phase stator windings until a turnoff time suited for preventing occurrence of a surge across the at least one of the at least two-phase stator windings appears, the second threshold voltage being set to be lower than the first threshold voltage; and turn off, at the appearance of the turnoff time, the switching element as the low-side rectifying element for the at least one of the at least two-phase stator windings.