A motive power output device that outputs motive power to a driving shaft, comprising:
- an internal combustion engine;
- an electric generator that inputs and outputs motive power;
- a three-shaft type motive power input/output device which is connected to three shafts that are the driving shaft, an output shaft of the internal combustion engine, and a rotating shaft of the electric generator, and which inputs motive power from or outputs motive power to one of the three shafts based on the motive power input from or output to the other two shafts of the three shafts;
- an electric motor that inputs motive power from and outputs motive power to the driving shaft;
- an electric storage device capable of allowing electric power to be sent and received between the electric generator and the electric motor;
- an input/output restriction setting device that sets an input/output restriction as a maximum electric power that is allowed to be charged into or discharged from the electric storage device based on a state of the electric storage device;
- a required torque setting device that sets a required torque that is required of the driving shaft;
- and
- a control device which operates the internal combustion engine based on a predetermined constraint in a range where setting conditions, including an input/output condition that a sum of an electric generator input/output electric power input to or output from the electric generator and an electric motor input/output electric power input to or output from the electric motor be within a range between the input and output restrictions set by the input/output restriction setting device, a drive torque condition that a sum of a torque that acts on the driving shaft based on a torque output from the electric generator and a torque that acts on the driving shaft based on a torque output from the electric motor be within a range from a value 0 to the required torque set by the required torque setting device, and an electric motor torque alteration condition that a torque output from the electric motor be within a permissible torque range in which alteration from the torque that the electric motor is outputting is permitted, are satisfied, and which also controls the internal combustion engine, the electric generator, and the electric motor so that the required torque set by the required torque setting device is output to the driving shaft.