Method for optimizing the energy consumption of a motor vehicle

A method, implemented in a computer (4) on board a motor vehicle (2), for optimization of the energy consumption of the vehicle (2), the vehicle (2) comprising a tank for fuel or hydrogen, an electric battery and/or super-capacitors (30) which can supply electrical energy, a thermal engine (M) which is supplied by the fuel tank or a fuel cell (P) supplied by the hydrogen tank, at least one electrical machine (ME) supplied with electrical energy provided by the battery and/or the super-capacitors (30), at least one device (10, 20) relating to the thermal engine (M) or to the fuel cell (P), at least one device (30) relating to the electrical machine (ME), and at least one device relating to the electric battery or the super capacitors (30), the itinerary of the vehicle (2) over a predetermined distance as well as the traffic conditions being predefined or predicted within the computer (4), the computer (4) being configured to control the traction chain of the motor vehicle (2) over a predetermined distance, said predetermined distance which the vehicle (2) must travel being segmented by the computer (4) into N successive segments of distances, N being a predefined whole number, said N−1 segments of distance corresponding to the N−1 first segments of the predetermined distance which the vehicle (2) must travel, said remaining segment of distance corresponding to the final segment of said predetermined distance, the computer (4) being able to control the thermal engine (M) or the fuel cell (P), the electrical machine (ME) and/or the devices (10, 20, 30) by the emission of a series of set-points, the thermal engine (M) or the fuel cell (P), the electrical machine (ME) and the devices (10, 20, 30) each being characterized by at least one variable of state, each variable of state making it possible to describe the operating state of the device which it characterizes, the assembly of the thermal engine (M) or the fuel cell (P), the electrical machine (ME) and the devices (10, 20, 30) being represented by a system of equations of state modelling the dynamics of the vehicle (2), said equations of state depending on at least instantaneous set-point values and variables of state, a series of associated states being associated with the equations of state and representing the conditions of the dynamic behavior of the vehicle (2), the energy consumption to be optimized being defined in an equation of criterion as being the sum of firstly the cumulative instantaneous consumption of fuel or of hydrogen of the thermal engine (M) or of the fuel cell (P), and secondly a corrective terminal term representing electrical energy extracted from, or stored in, the electric battery or the super-capacitors (30), the corrective terminal term depending on the difference of state of charge between firstly the state of charge of the electric battery or the super-capacitors (30) at the end of the predetermined distance, and secondly the state of charge of the electric battery or the super-capacitors (30) at the start of the predetermined distance, said corrective term being a linear function defined by a factor of proportionality, said method being implemented during a period divided into constant sampling instants, the method comprising, at each sampling instant, the steps of:

• calculation (28), for each set-point, of all the possible values of a Hamiltonian function of said set-point, using at least the equation of criterion;
• and
• determination (31) of the value of each set-point for which said Hamiltonian function is the weakest,
• characterized in that the computer (4) is configured to define one or more target value(s) for the associated states on N−1 segments of distance, and to define one or more target value(s) for the final states of the variables of state on the remaining segment of distance, according to conditions of traffic which are predefined or predicted within the computer (4), the common variables of state being selected by the computer (4) as initial states, and in that the method also comprises a phase (32) of updating of the equation of criterion, said phase (32) comprising the steps of:
• selection (36) of a first initial value for the associated states;
• calculation (38), according to said initial states and to the first initial value selected for the associated states, as well as to an internal model pre-implanted in the computer (4), of a first simulation of the internal model for said conditions of traffic predefined or predicted within the computer (4), a first pair of values formed by energy consumption of the vehicle (2), and a difference of state of charge of the electric battery or of the super-capacitors (30) being obtained upon completion of the step (38) of calculation of the first simulation;
• if, upon completion of the step (38) of calculation of the first simulation, the target values for the final states of the variables of state or of the associated states are not obtained:
• selection (40) of a second initial value for the associated states, distinct from the first initial value;
• calculation (42), according to said initial states and to the second initial value selected for the associated states, as well as to the internal model, of a second simulation of the internal model for said conditions of traffic predefined or predicted within the computer (4), a second pair of values formed by energy consumption of the vehicle (2), and a difference of state of charge of the electric battery or of the super-capacitors (30) being obtained upon completion of the step (42) of calculation of the second simulation;
• if, upon completion of the step (42) of calculation of the second simulation, the target values for the final states of the variables of state or of the associated states are not obtained:
• calculation (44), according to the first and second pairs of values of energy consumption of the vehicle (2) and to difference of state of charge of the electric battery or of the super-capacitors (30), of a first estimation of the proportionality factor, using a method of predefined estimation of gradient, the first estimation of the proportionality factor being used to update the equation of criterion of the energy consumption to be optimized;
• and
• loopback of the preceding steps (36, 38, 40, 42, 44), until the target values for the final states of the variables of state or of the associated states are obtained, the computer (4) being configured to impose on the associated states, on said N−1 segments of distance, convergence towards a target value, the value of which corresponds to said proportionality factor.