Optimal design and power management control of hybrid biofuel–electric powertrain

Abstract

This paper presents a multi-objective optimization procedure for a hybrid biofuel–electric vehicle (HBEV) powertrain design and fuzzy logic control. The vehicle concept is based on an electric drivetrain, while the battery is recharged by an onboard generator coupled to an ethanol-powered engine. The optimization procedure is done by the interactive adaptive-weight genetic algorithm method, aiming for the minimization of the fuel consumption, tailpipe emissions, powertrain size, and charging time, while the battery lifespan is improved. The powertrain parameters are defined as design variables, along with the membership functions, rules, and weights of the fuzzy logic controllers, responsible for the power split among the four in-wheel electric motors, the engine and generator operation. The optimization is done under the combination of four standard driving cycles combined in a 4 times loop, resulting in a 281.8 km path. As compared to a conventional vehicle with the same engine data, the best HBEV solution was able to save 17.78% fuel, while decreasing the emissions by 52.38% HC, 22.85% CO, and 28.57% NOx, considering a battery life expectation of 23,907 h. Moreover, this optimum HBEV was also evaluated under two combinations of real-world driving cycles, reaching fuel savings up to 30% and lower emissions as compared to the conventional vehicle in all analyzed scenarios. Finally, a cost analysis is performed to compare the proposed HBEV powertrain concept with other hybrid vehicle configurations presented in the literature.