Power output apparatus and method of controlling the same

Abstract

In a hybrid vehicle, there is a shock in a transient period when a driving condition of an internal combustion engine is shifted from a loaded driving state for power generation, in which a load is applied to the internal combustion engine by a motor generator, to a non-loaded driving state for idling or motoring, in which no load is applied to the internal combustion engine. A hybrid power output apparatus of the present invention, in which the motor generator is mechanically linked with the internal combustion engine, prevents an abrupt change in output torque from the motor generator in the transient period from the loaded driving state to the non-loaded driving state. One procedure to attain this object sets the minimum revolving speed of the internal combustion engine in the loaded driving state to be greater than the revolving speed in the non-loaded driving state by approximately 200 rpm. This setting enables the revolving speed of the internal combustion engine to gradually vary in the transient period from the loaded driving state to the non-loaded driving state, and prevents an abrupt change of the torque output from the motor generator, which is under the PI control based on the revolving speed of the internal combustion engine. This accordingly reduces a shock due to the abrupt change of the torque.