Optimization of the energy performance of a hybrid vehicle

Abstract

Parallel hybrid car is composed of an internal combustion engine, a reversible electric machine and a battery. The heat engine is powered by chemical energy stored in the fuel. For vehicle traction, the two machines can operate at the same time or separately. The battery can be charged at the same time with the vehicle's traction or while it is stopped, we speak of hybrid mode with battery charging. One can also take advantage of energy recovery by enumerative braking along a road downhill or / and during a deceleration of the speed of the car. In the event that the vehicle is only towed with the electric machine, this is referred to as pure electric mode. The case where the two machines intervene at the same time to the traction of the vehicle corresponds to the assistance mode. Like the conventional car, the hybrid car can operate in pure thermal mode. In actual operation of the vehicle, the route is unknown in advance. To minimize fuel consumption, the powertrain system must operate instantly at its best fuel efficiency. This work deals with the case where the vehicle route and driving conditions are unknown in advance (real case). In this condition, we propose an optimal control strategy based on instant criterion that we have developed. These allow the maximization of the overall and instantaneous efficiency of the powertrain system of a parallel hybrid vehicle in each mode of operation.