Patent ID: 8564255

Claim:
A vehicle-use electric rotating machine comprising: a switching section including a plurality of upper and lower arms each constituted of a switching element parallel-connected with a diode and connected to a corresponding one of a plurality of phase windings of an armature winding of the electric rotating machine so as to form a bridge circuit to rectify an AC voltage induced in each of the phase windings; an on-timing setting section for setting an on timing of each of the switching elements; a rotational speed calculating section for calculating a rotational speed of the electric rotating machine; a target electrical angle setting section configured to set a value of a target electrical angle in accordance with the rotational speed calculated by the rotational speed calculating section for each of the upper and lower arms, the target electrical angle representing a time period in electrical angle from when the switching element is turned off to when a conduction period ends, the conduction period representing a time period from when a phase voltage of the phase winding reaches a first threshold value to when the phase voltage reaches a second threshold value different from the first threshold value; an off-timing setting section for setting an off timing of each of the switching elements such that the time period in electrical angle from when the switching element is turned off to when the conduction period ends is equal to the value of the target electrical angle; and a switching element driver section for driving each of the switching elements in accordance with the on timing set by the on-timing setting section and the off timing set by the off-timing setting section.