Power output device and control method of the power output device and hybrid vehicle driven by the power output device

A control method for a power output device having an internal combustion engine with an output shaft, an electric motor for generating and receiving electric power and for rotating a rotation shaft, a drive shaft mechanically connected to the output shaft of said internal combustion engine and the rotation shaft of said electric motor for rotating at the same rotation speed as or a different rotation speed from the output shaft, and a battery for supplying electric power to said electric motor and for storing electric power from said electric motor, comprising:

• determining output torque of said internal combustion engine and relating the output torque to a requested power;
• feedback-controlling said electric motor so that the output power from said drive shaft is equal to the requested power;
• and
• controlling said electric motor so that the output torque of said electric motor is substantially zero when the output torque of said internal combustion engine is substantially zero.

A hybrid vehicle with a wheel shaft driven by a power output device comprising:

• an internal combustion engine having an output shaft;
• an electric motor for generating and receiving electric power and for rotating a rotation shaft;
• a drive shaft connected to said wheel shaft and mechanically connected to the output shaft of said internal combustion engine and the rotation shaft of said electric motor for rotating at the same rotation speed as or a different rotation speed from the output shaft;
• a battery for supplying electric power to said electric motor and storing electric power from said electric motor;
• a torque determinater for determining output torque of said internal combustion engine and for relating the output torque to a requested power;
• an electric motor controller that feedback-controls said electric motor so that the output power from said drive shaft is equal to the requested power;
• a lock determinater that determines whether said wheel shaft is locked or not;
• and
• a second electric motor controller that controls said electric motor so that the output torque of said electric motor is substantially zero when the output torque of said internal combustion engine is substantially zero.