Power output apparatus and a control method thereof

A power output apparatus 20 of the present invention implements a smooth switching between the connection of a rotor-rotating shaft 38 of an assist motor 40 with a crankshaft 56 of an engine 50 and the connection of the rotor-rotating shaft 38 of the assist motor 40 with a drive shaft 22, and enables the power output from the engine 50 to be output to the drive shaft 22 with a high efficiency. The power output from the engine 50 is converted to a desired power by a clutch motor 30 having rotors 31 and 33 respectively linked with the crankshaft 56 and the drive shaft 22 and by the assist motor 40 connected to either the crankshaft 56 or the drive shaft 22 via a first clutch 45 and a second clutch 46, and is output to the drive shaft 22. The connection of the assist motor 40 is switched in the state where both the clutches 45 and 46 are set in ON position, when the revolving speed of the engine 50 is made coincident with the revolving speed of the drive shaft 22. This effectively reduces a variation in torque output to the drive shaft 22 in the course of the switching operation and enables the power to be output to the drive shaft 22 even in the course of the switching operation.