Driving force control method and device for hybrid vehicle

A driving force control device for a hybrid vehicle equipped with an internal combustion engine, a driving force transmission mechanism for transmitting driving force of the internal combustion engine to drive wheels, and an electric motor coupled to the internal combustion engine and capable of outputting driving force to the driving force transmission mechanism, the driving force control device comprising a processor configured to:

• estimate an average torque output by the internal combustion engine;
• estimate a torque fluctuation component of the average torque output by the internal combustion engine;
• set a countertorque for suppressing the estimated torque fluctuation component;
• and
• control the electric motor to output the set countertorque, wherein
• the processor is configured to implement setting the countertorque under a condition that the average torque output by the internal combustion engine is constant, when an engine speed of the internal combustion engine is equal to or greater than a first given value, to set a negative control gain such that, as the engine speed of the internal combustion engine becomes higher, an absolute value of the negative control gain becomes smaller, and then to set the countertorque based on a product of the estimated torque fluctuation component and the negative control gain, and
• the processor is further configured to implement setting the countertorque, under a condition that the engine speed of the internal combustion engine is constant, when the average torque output by the internal combustion engine is equal to or greater than a second given value, to set the negative control gain such that, as the average torque output by the internal combustion engine becomes larger, the absolute value of the negative control gain becomes smaller.