To restrain sudden change of driving force to a driving shaft based on torque limitation in a lock range of a power generator in a power output device including a 3-axis power input/output device such as a planetary gear mechanism in which three rotational elements are connected to the driving shaft, an output shaft of an internal combustion engine and a rotary shaft of the power generator.

In the lock range in which the absolute value of a motor rotational frequency Nm1 is under a value N1, torque based on an inverter cooling water temperature Tinv is coded to set torque limitation, in an ordinary range in which the absolute value of the motor rotational frequency Nm1 is equal to or more than a value N2, rated maximum torque Tmax is coded to set torque limitation, and in a transition range in which the absolute value of the motor rotational frequency Nm1 is equal to or more than N1 and under the value N2, torque smoothly connecting the torque of the lock range and the rated maximum torque Tmax to a change in the motor rotational frequency Nm1 is set as torque limitation. Thus, even if the motor rotational frequency Nm1 suddenly changes extending between the value N1 and the value N2, a sudden change in torque to the driving shaft can be restrained.

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