Patent ID: 8292778

Claim:
An idle-stop restart control system comprising: a sensorless synchronous motor-generator including an armature winding and a rotor including a field winding, the sensorless synchronous motor-generator operating as a generator after start of an engine and operating as a starting motor when the engine is restarted after idle stop; an induced-signal detecting circuit for detecting an induced signal output from the armature winding; a field drive circuit for controlling energization of the field winding; and a restart control circuit being configured to: output, to the field drive circuit, a drive signal for controlling the energization of the field winding to amplify the induced signal while calculating a number of revolutions and an angular position of the rotor based on the induced signal detected by the induced-signal detecting circuit when an engine stop command is input and a level of the induced signal detected by the induced-signal detecting circuit is equal to or less than a predetermined value; and output the drive signal for controlling the energization of the armature winding to restart the engine based on the calculated number of revolutions and angular position of the rotor when a restart command is input.