In order to study the control effect of speed ratio change on fuel economy performance of vehicles under complex
working conditions, a mixed fuzzy-PI control strategy is proposed, and a dynamic simulation model is established for the
best fuel economy. Simulation and analysis are conducted using the model under different typical operating conditions.
Simulation results show that the speed ratio mixed fuzzy-PI controller has a better following characteristics and higher
accuracy compared to a conventional fuzzy controller. Even in the case of external disturbance, the target engine speed
can still be maintained at the most economic working point. According to the proposed control strategy, road test has
been done under various running situations with DEAWOOD MatizII passenger car used as an experimental sample car.
The test results verify further that the model established is correct and the control strategy proposed for the speed ratio is
valid, and the reasonable match between engine and continuously variable transmission (CVT) is achievable.