Method for managing torque distribution in a hybrid vehicle
A computer for managing the drive train of a hybrid vehicle including an internal combustion engine, an electric machine and a battery. The drive train being capable of operating in a plurality of charging or discharging modes of the battery, the computer determines a set of probabilities of activation of the mode, determines the value of the speed of the electric motor for each mode, determines a set of electrical powers of the electric machine, calculates an energy consumption reduction indicator, determines the torque requested by the driver, the value of the speed of the internal combustion engine and the speed of the vehicle, determines a torque to be applied to the electric machine, and sends a command to the electric machine on the basis of the torque to be applied to the electric machine determined.
1. A computer for managing the drive train of a hybrid vehicle comprising at least one internal combustion engineer, at least one electric machine and at least one battery, said drive train being capable of operating in a plurality of modes, each mode being either a battery charging mode or a battery discharging mode, said computer being configured to:
a. determine a set of probabilities of activation of said mode (p ch {i}, p dch {i}) as a function of:
i. a predetermined set of probabilities of occurrence (p occ {i}) of a set of triplets ({i}) of values comprising the torque requested by the driver (TQ req ), the speed (N th ) of the internal combustion engine ( 20 ) and the speed (V s ) of the vehicle,
ii. a predetermined table of cost values (T C {i}), said cost (T C ) representing the quantity of fuel consumed for a unit of electrical energy stored by the battery in the case of the charging of the battery or the quantity of fuel saved for a unit of electrical energy consumed by the battery in the case of the discharging of the battery,
iii. and a pair of thresholds comprising a charging cost threshold and a discharging cost threshold,
b. determine the set of values of the speed (N elec {i}) of the electric machine ( 40 ), each speed value (N elec {i}) corresponding to a triplet ({i}),
c. for each mode, determine a set of electrical powers (P elec CH {i}, p elec DCH {i}) of the electric machine ( 40 ) as a function of the set of activation probabilities (p ch {i}, p dch {i}) determined, a predetermined table of torque values (TQ{i}) to be applied to the electric machine ( 40 ), and the speed (N elec {i}) of the electric machine ( 40 ) determined,
d. calculate an energy consumption reduction indicator (B) on the basis of the set of electrical powers (P elec CH {i}, p elec DCH {i}) determined and the table of cost values (T C {i}),
e. determine a pair of thresholds (S ch , S dch ) comprising a charging cost threshold (S ch ) and a discharging cost threshold (S dch ) maximizing the energy consumption reduction indicator calculated,
f. determine the torque requested by the driver (TQ req ), the value of the speed (N th ) of the internal combustion engine and the speed (V s ) of the vehicle,
g. determine a torque to be applied to the electric machine on the basis of the torque requested by the driver (TQ req ) determined, the value of the speed (N th ) of the internal combustion engine determined, the speed (V s ) of the vehicle determined, the threshold pair (S ch , Sach) determined, the predetermined table of torque values (TQ{i}) and the predetermined table of cost values (T C {i}), and
h. send a command to the electric machine on the basis of the torque to be applied to the electric machine determined.
2. The computer as claimed in claim 1 , being configured to determine the set of probabilities of occurrence (p occ {i}); to this end, the computer is configured to:
a. define an initial set of probabilities of occurrence (p occ {i}) of triplets ({i}) of values,
b. reduce each probability of occurrence (p occ {i}) of the triplets ({i}) so that it is zero after a maximum of N iterations, the triplet ({i}) of values not having been encountered/measured during these N iterations, N being a natural number,
c. determine the sum (S p ) of the set of probabilities of occurrence (p occ {i}) of all of the triplets ({i}),
d. adjust the probability of occurrence (p occ {i}) of the triplet ({i}) the values of which are closest to the current values of the torque requested by the driver (TQ req ), the speed (N th ) of the internal combustion engine and the speed (V s ) of the vehicle, so that the sum (S p ) of the set of probabilities of occurrence (p occ {i}) is equal to 1.
3. A hybrid vehicle comprising at least one internal combustion engine, at least one electric machine, at least one battery and a computer as claimed in claim 1 .
4. A method for managing the drive train of a hybrid vehicle comprising at least one internal combustion engine, at least one electric machine and at least one battery, said drive train being capable of operating in a plurality of modes, each mode being either a battery charging mode or a battery discharging mode, said method being implemented by a computer as claimed in claim 1 , said method comprising:
a. an iterative phase comprising the steps of:
i. for each mode, determining a set of probabilities of activation of said mode (p ch {i}, p dch {i}) as a function of:
1. A predetermined set of probabilities of occurrence (p occ {i}) of a set of triplets of values comprising the torque requested by the driver (TQ req ), the speed (N th ) of the internal combustion engine ( 20 ) of the vehicle and the speed (V s ) of the vehicle,
2. A predetermined table of cost values (T C {i}), said cost (T C ) representing the quantity of fuel consumed for a unit of electrical energy stored by the battery in the case of the charging of the battery or the quantity of fuel saved for a unit of electrical energy consumed by the battery in the case of the discharging of the battery,
3. And a pair of thresholds (S ch , S dch ) comprising a charging cost threshold (S ch ) and a discharging cost threshold (S dch ),
ii. determining the set of values of the speed (N elec {i}) of the electric machine, each speed value (N elec {i}) corresponding to a triplet ({i}),
iii. for each mode, determining a set of electrical powers (P elec CH {i}, p elec DCH {i}) of the electric machine ( 40 ) as a function of the set of activation probabilities (p ch {i}, p dch {i}) determined, a predetermined table of torque values (TQ{i}) to be applied to the electric machine, and the speed (N elec ) of the electric machine determined,
iv. calculating an energy consumption reduction indicator on the basis of the set of electrical powers (P elec CH {i}, p elec DCH {i}) determined and the table of cost values (T C {i}),
b. a phase of determining a pair of thresholds (S ch , S dch ) comprising a charging cost threshold (S ch ) and a discharging cost threshold (S dch ) maximizing the energy consumption reduction indicator calculated,
c. a command phase comprising the steps of:
i. determining the torque requested by the driver (TQ req ), the value of the speed (N th ) of the internal combustion engine ( 20 ) and the speed (V s ) of the vehicle,
ii. determining a torque to be applied to the electric machine on the basis of the torque requested by the driver (TQ req ) determined, the value of the speed (N th ) of the internal combustion engine determined, the speed (V s ) of the vehicle determined, the threshold pair (S ch , S dch ) determined, the predetermined table of torque values (TQ{i}) and the predetermined table of cost values (T C {i}),
iii. sending a command to the electric machine on the basis of the torque to be applied to the electric machine determined.
5. The method as claimed in claim 4 , in which, during the step of determining the set of probabilities of activation of a charging mode (p ch {i}), said charging mode is detected if the cost value (T c {i}), for a given triplet ({i}), is below the charging threshold (S ch ).
6. The method as claimed in claim 4 , in which, during the step of determining the set of probabilities of activation of a discharging mode (p dch {i}), said discharging mode is detected if the cost value (T c {i}), for a given triplet ({i}), is above the discharging threshold (S dch ).
7. The method as claimed in claim 4 , comprising a preliminary phase (PH 1 ), making it possible to determine the set of probabilities of occurrence (p occ {i}), comprising:
a. an initialization step, in which an initial set of probabilities of occurrence (p occ {i}) of triplets ({i}) of values is defined,
b. a reduction step, in which each probability of occurrence (p occ {i}) of the triplets ({i}) is reduced so that it is zero after a maximum of N iterations, the triplet ({i}) of values not having been encountered/measured during these N iterations, N being a natural number,
c. a step (E 03 ) of determining the sum (S p ) of the set of probabilities of occurrence (p occ {i}) of all of the triplets ({i}),
d. an adjustment step, in which the probability of occurrence (p occ {i}) of the triplet ({i}) the values of which are closest to the current values of the torque requested by the driver (TQ req ), the speed (N th ) of the internal combustion engine and the speed (V s ) of the vehicle, is adjusted so that the sum (S p ) of the set of probabilities of occurrence (p occ {i}) is equal to 1.
8. The method as claimed in claim 4 , in which the energy consumption reduction indicator (B) is defined according to the following formula:
B
=
(
(
∑
i
,
m
o
d
e
P
elec
m
o
d
e
{
i
}
+
P
1
2
V
_
)
>
0
)
*
∑
i
,
m
o
d
e
(
-
P
e
1
e
c
m
o
d
e
{
i
}
*
T
c
{
i
}
)
where mode=CH, DCH, and represents the charging or discharging operating mode of the battery ( 30 ), P elec mode {i} represents the electrical power consumed or generated by the electric machine ( 40 ), for the operating mode in question and for the triplet ({i}),
P 12V
represents the average electrical power from the storage battery, consumed at 12 V by the auxiliary equipment of the vehicle, such as the power supply for the computers, the windscreen wiper motor, window lifts, etc.,
(
∑
i
,
m
o
d
e
P
elec
m
o
d
e
{
i
}
+
P
1
2
V
_
)
represents the electrical power used by the storage battery, and
(
(
∑
i
,
m
o
d
e
P
elec
m
o
d
e
{
i
}
+
P
1
2
V
_
)
>
0
)
is a condition which, when it is not met, makes it possible to reject operating modes resulting in the discharging of the battery,
∑
i
,
m
o
d
e
(
-
P
e
1
e
c
m
o
d
e
{
i
}
*
T
c
{
i
}
)
represents the expected variation in fuel consumption resulting from the selection of the mode(s) to be activated.
9. The method as claimed in claim 7 , in which the preliminary phase, the iterative phase and the determination phase are performed every second.
10. The method as claimed in claim 4 , in which the command phase is repeated every 10 milliseconds.