Power transmission device

A power transmission device, comprising:

• a first rotor, to which power from an engine is transmitted, and provided with a rotor conductor that can generate a rotating field by application of an alternating current;
• a stator provided with a stator conductor that can generate a rotating field by application of an alternating current;
• a second rotor relatively rotatable with respect to the first rotor, wherein torque acts between the first rotor and the second rotor in accordance with the action of the rotating field generated at the rotor conductor, and torque acts between the second rotor and the stator in accordance with the action of the rotating field generated at the stator conductor;
• a first electric power converter that converts electric power between an electric power storage device and the stator conductor;
• a second electric power converter that converts electric power between the rotor conductor and at least one of the electric power storage device and the first electric power converter;
• a power transmission/interruption mechanism that either permits or cuts off the power transmission from the second rotor to a drive axle;
• and
• a control unit that controls the electric power conversion at the first electric power converter to control the torque to be applied between the stator and the second rotor using the alternating current of the stator conductor, and that controls the electric power conversion at the second electric power converter to control the torque to be applied between the first rotor and the second rotor using the alternating current of the rotor conductor, wherein in the case of starting the engine in a state where the drive axle is at a stop the control unit implements an inertial energy storage operation for rotating the second rotor by applying torque to the second rotor from the stator using the alternating current of the stator conductor in a state where the power transmission from the second rotor to the drive axle is cut off by the power transmission/interruption mechanism;
• and
• a cranking operation for cranking the engine by rotating the first rotor by applying torque to the first rotor from the second rotor using the alternating current of the rotor conductor after the inertial energy storage operation.