METHOD FOR CONTROLLING AN ENERGY EQUIVALENCE FACTOR FOR A HYBRID MOTOR VEHICLE

Abstract

A method controls an energy equivalence factor of a motor vehicle including a heat engine and at least one electric motor powered by a storage battery. The method includes estimating a value of the energy equivalence factor proportional to a predetermined maximum value when the difference is lower than the threshold value or proportional to a predetermined minimum value when the difference is higher than the threshold value.

Claims

1-6. (canceled)

7. A method for controlling an energy equivalence factor corresponding to a weighting value applied between a supply of heat energy and a supply of electrical energy, in order to minimize on one operating point an overall energy consumption of a hybrid drive train for an automobile vehicle comprising a heat engine and at least one electric motor powered by an electrical accumulator, the method comprising: estimating a value of said energy equivalence factor as a function of a difference between an instantaneous value of an energy state of the electrical accumulator and a target value of the energy state of the electrical accumulator, wherein estimating includes: comparing said difference with at least one positive threshold value and at least one negative threshold value, and calculating the estimated value of the energy equivalence factor, said estimated value being: proportional to a predetermined maximum value when said difference is less than said negative threshold value, or proportional to a predetermined minimum value when said difference is greater than said positive threshold value, or a function of said difference, of said negative threshold value and said positive threshold value, and of the predetermined minimum and maximum values when said difference is in a range between the negative threshold value and the positive threshold value.

8. The control method as claimed in claim 7, wherein said positive threshold value and said negative threshold value are opposing.

9. The control method as claimed in claim 7, further comprising: integrating when said estimated value of the equivalence factor is in the range between the negative threshold value and said positive threshold value, said integrating defining an integrated term to be added to said estimated value.

10. The control method as claimed in claim 7, further comprising: limiting said estimated value of the energy equivalence factor during which said estimated value is limited by boundaries defined by said predetermined minimum value and by said predetermined maximum value.

11. A device for controlling an energy equivalence factor corresponding to a weighting value applied between a supply of heat energy and a supply of electrical energy, in order to minimize on one operating point an overall energy consumption of a hybrid drive train for an automobile vehicle comprising a heat engine and at least one electric motor powered by an electrical accumulator, said device comprising: means for receiving an instantaneous value of an energy state of the electrical accumulator; means for calculating a difference between said instantaneous value of the energy state of the electrical accumulator and a target value of the energy state of the electrical accumulator; means for comparing said difference with at least one positive threshold value and at least one negative threshold value; and means for calculating an estimated value of the energy equivalence factor, said estimated value being: proportional to a predetermined maximum value when said difference is less than said negative threshold value, or proportional to a predetermined minimum value when said difference is greater than said positive threshold value, or a function of said difference, of said negative threshold value and positive threshold value, and of the predetermined minimum and maximum values when said difference is in the range between the negative threshold value and the positive threshold value.

12. An automobile vehicle comprising: the device for controlling the energy equivalence factor as claimed in claim 11.

Description

[0048] With reference to the single FIGURE, the control method 1 providing a control of the energy equivalence factor of a hybrid automobile vehicle comprises a step 2 for estimating a value K.sup.calc of the energy equivalence factor K.

[0049] The estimation step 2 first of all comprises a first step 5 for calculating an error , in which the calculation is performed of the value of the difference , also commonly referred to as the error a, between the instantaneous value soe of the energy state of the electrical accumulator and the target value soe.sub.ref of the energy state of the electrical accumulator.

[0050] The calculation 5 of the error is carried out by the subtraction soesoe.sup.ref of the target value soe.sup.ref from the instantaneous value soe of the energy state.

[0051] The error may be a positive or negative value.

[0052] Generally speaking, the error is negative when the target value soe.sup.ref is small, for example between 0% and 10% of the maximum value of the energy state of the electrical accumulator. In this case, the control will aim to discharge the electrical accumulator, and hence to promote the consumption of electrical energy.

[0053] In the opposite case, the error is positive when the target value soe.sup.ref is large, for example between 90% and 100% of the maximum value of the energy state of the electrical accumulator. In this case, the control will aim to recharge the electrical accumulator.

[0054] After the error calculation step 5, a step is carried out for comparison 6 between the error and two threshold values .sub.soe, .sub.soe.

[0055] Here, the error is compared with two threshold values, a positive threshold value .sub.soe, and a negative threshold value .sub.soe.

[0056] The two threshold values are opposing. In other words, the two threshold values .sub.soe, .sub.soe are equal in absolute value.

[0057] According to one alternative, the two threshold values may have different absolute values.

[0058] Preferably, the threshold values .sub.soe, .sub.soe are close to zero in absolute value, for example in the range between 0 and 1.

[0059] The comparison step 6 differentiates three cases: [0060] Where the error is less than the negative threshold value .sub.soe, [0061] Where the error is greater than the positive threshold value .sub.soe; [0062] Where the error is in the range between the negative threshold value [0063] .sub.soe and the positive threshold value .sub.soe.

[0064] Depending on the result of the comparison step 6, a step 7 for calculation of the estimated value K.sup.calc of the energy equivalence factor K is then carried out.

[0065] If the error is less than the negative threshold value .sub.soe, the estimated value K.sup.calc is determined by the following calculation:

[00001]$\begin{array}{cc}{\stackrel{\_}{K}}^{\mathrm{calc}}=\frac{K^{\max }}{}& \left(1\right)\end{array}$

[0066] in which: [0067] K.sup.max is a maximum acceptable value of the equivalence factor, and [0068] is a predetermined value greater than 1.

[0069] The value is a pre-calibrated and constant value.

[0070] If the error is greater than the positive threshold value .sub.soe, the estimated value K.sup.calc is determined by the following calculation:

[00002]$\begin{array}{cc}{\stackrel{\_}{K}}^{\mathrm{calc}}=\frac{K^{\min }}{}& \left(2\right)\end{array}$

[0071] in which: [0072] K.sup.min is a minimum acceptable value of the equivalence factor.

[0073] The maximum acceptable value K.sup.max and minimum acceptable value K.sup.min of the energy equivalence factor are predetermined depending on the electrical accumulator. In other words, these values are operating constants of the electrical accumulator.

[0074] If the error is in the range between the negative threshold value .sub.soe and the positive threshold value .sub.soe, the estimated value K.sup.calc is determined by the following calculation:

[00003]$\begin{array}{cc}{\stackrel{\_}{K}}^{\mathrm{calc}}=\frac{\left(+{\mathrm{.Math.}}_{\mathrm{soe}}\right).Math.K^{\min }-\left(-{\mathrm{.Math.}}_{\mathrm{soe}}\right).Math.K^{\max }}{2.Math.{\mathrm{.Math.}}_{\mathrm{soe}}}& \left(3\right)\end{array}$

[0075] According to one alternative, the error could be compared with a single threshold value .sub.soe, for example a value close to zero, less than or greater than zero, or else equal to zero.

[0076] In this alternative, the comparison step 6 and calculation step 7 will be similar to those previously described for two threshold values, with the exception that the comparison 6 will only take into account the case where the error is greater or less than the single threshold value .sub.soe; and the calculation step 7 will only then consider the first two calculations (1) and (2) previously described, by simply substituting the negative and positive values with the single threshold value, the third calculation (3) only being appropriate when two threshold values are taken into account.

[0077] Thus, the estimated value K.sup.calc of the energy equivalence factor is obtained by a robust estimation step 2.

[0078] In other words, a value of the energy equivalence factor is estimated independently of the driving conditions of the automobile vehicle, or of the physical parameters of the automobile vehicle.

[0079] This estimation step 2 is consequently relatively simple to adapt to various systems and does not require any complex and costly calibration in order to function.

[0080] Furthermore, the estimation step 2 is adaptive. This is because, during this step, the error is estimated prior to evaluating the estimated value K.sup.calc. In other words, the present method studies the system prior to acting.

[0081] In this way, a value K.sup.calc of the energy equivalence factor may be estimated in a robust and adaptive manner.

[0082] After having estimated the value K.sup.calc of the energy equivalence factor K, during the estimation step 2, the method carries out an integration step 3.

[0083] During the integration step 3, an integrated term 8 is determined as a function of the error : [0084] if the error is in the range between the negative threshold value .sub.soe and the positive threshold value .sub.soe, the integrated term 8 is a function of a predefined gain k.sub.iG. In other words, the integrated term 8 corresponds, after a Laplace transform, to the function

[00004]$\frac{1}{p}.Math.k_i.Math.G.Math..Math.;$

and [0085] if the error is less than the negative threshold value .sub.soe or if the error is greater than the positive threshold value .sub.soe, the integrated term 8 is equal to zero.

[0086] After having determined the integrated term 8, it is added to the estimated value K.sup.calc during a step 9 for summing the integration step 3, as a function of the value of the error , such as described hereinabove.

[0087] The integration step 3 allows the variation of the energy equivalence factor K to be smoothed when the instantaneous value soe of the energy state of the electrical accumulator is relatively close to the target energy state soe.sup.ref. At the end of the integration step, a smoothed value K.sup.calc of the estimated value K.sup.calc is obtained.

[0088] Indeed, the positive threshold values .sub.soe and negative threshold values .sub.soe are values that are relatively close to zero, defining thresholds between which the error is considered as small. The idea is then to stabilize the variations of the energy equivalence factor K in order to optimize the overall energy consumption.

[0089] After the integration step 3, a limitation step 4 is carried out, during which it is verified that the smoothed value K.sup.calc is in the range between the maximum acceptable value K.sup.max and minimum acceptable value K.sup.min of the energy equivalence factor. If the smoothed value K.sup.calc goes outside of these limits, it is brought back to the nearest maximum or minimum value.

[0090] In other words, a saturation 4 of the smoothed values K.sup.calc is carried out in order to keep them between the maximum acceptable values K.sup.max and minimum acceptable values K.sup.min of the energy equivalence factor. This allows a correct operation of the system to be ensured at all times during operation, notably in such a manner as not to cause any risk of deterioration of the electrical accumulator.

[0091] The value obtained after the limitation step 4 corresponds to the value of the energy equivalence factor K controlled by the method.

[0092] The invention is in no way limited to the embodiment described.

[0093] In particular, the integration step 3 and limitation step 4 are optional steps, which may or may not be present, independently of one another, of the control is method 1 implemented.