Patent ID: 8716983

Claim:
A vehicle-use electric rotating machine comprising: an armature winding including two or more phase windings; a switching section having a bridge circuit for rectifying a voltage induced in the armature winding, the bridge circuit including, for each of the phase windings, an upper arm and a lower arm each constituted of a switching element parallel-connected with a diode; a rotational speed calculating section for calculating a rotational speed of the electric rotating machine; an on timing setting section for setting an on timing of the switching element; a target electrical angle setting section configured to set a value of a target electric angle, the target electrical angle representing in electrical angle a margin period between a time at which the switching element is turned off and a time at which a conduction period ends, the conduction period representing a period from when a phase voltage of one of the phase windings reaches a first threshold voltage to when the phase voltage reaches a second threshold voltage different from the first threshold voltage, an off timing setting section configured to set an off timing of the switching element such that the margin period is equivalent to the set value of the target electrical angle; and a switching element driving section configured to drive each of the switching elements such that the switching element is turned on at the timing set by the on timing setting section and turned off at the off timing set by the off timing setting section, wherein when a time difference represents a first electrical angle minus the target electrical angle, the first electrical angle representing a period in electrical angle from the previous off timing of the switching element to when the phase voltage has reached the second threshold voltage, the off timing setting section corrects, for each of the switching elements, the off timing of the switching element by a correction amount depending on the time difference, the off timing setting section being configured to set the correction amount to a larger value when the time difference is detected to be outside a normal range than when the time difference is detected to be within the normal range.