Patent ID: 7268441

Claim:
A control device for motor generator characterized by comprising a motor generator having a stator with an armature winding wound thereon and a rotor of claw-pole shape with a field winding wound thereon, an inverter unit that sends and receives electric power to and from the armature winding, a field circuit that controls a field current flowing through the field winding, and a control circuit that controls the inverter unit an the field circuit, wherein an engine is started and power generation is performed while a vehicle is running, wherein a field current limit value Ifm in electric driving to start the engine is larger than a field current limit value Ifg in power generation, in the power generation, an inverter mode in a low rotation speed zone for boosting and an alternator mode in a high rotation speed zone for rectifying and outputting a generated voltage without boosting are provided, a field current limit value Ifgi in the inverter-mode power generation and a field current limit value Ifga in the alternator-mode power generation are set differently from each other, and the larger value is set as the value Ifg.