A method for allocating electric power to a set of users characterized by respective priority levels

Abstract

A method for allocating an available power B avl suppliable from a source (S) to a plurality of M users of a vehicle (V). The method comprises defining a priority order of the M users, which identifies, for each N-th user in the plurality of M users, a first set comprising the 1st to the (N-1)-th users having a higher priority than the N-th user, and a second set of users comprising the (N+1)-th to the M-th users having a lower priority than the N-th user. The method moreover comprises defining, for each N-th user, a maximum value (Formula (I)) for the absolute value of the power absorbed by that user as a function of the available power B avl , a power absorbed (Formula (II)) by each of the users of the second set, a power reserve (Formula (III)) of each of the users of the second set, a power absorbed (Formula (IV)) by the users of the first set, a power reserve for the N-th user (Formula (V)), and a minimum threshold value. Subsequently, the available power B avl suppliable by the source (S) is allocated while imposing that, for each N-th user, the absolute value of the power absorbed (Formula (VI)) by the N-th user must be less than or equal to the maximum value (Formula (VII)) defined for that user (Formula (VIII)).

Description

[0001] "A method for allocating electric power to a set of users characterized by respective priority levels"

[0002] ★★★★

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The present invention refers to at least partly electric traction propulsion systems, including both vehicles with purely electric traction (BEV) and vehicles equipped with a hybrid powertrain, in the various configurations thereof (PHEV, MHEV, HEV, etc.).

[0006] Known Art

[0007] In electric traction vehicles the challenge is encountered of efficiently managing the electric power supplied by a source (such as a battery or a battery pack mounted on board the vehicle, for example) to the various components of the vehicle which are powered thereby .

[0008] Nowadays, the algorithms for determining how to allocate the power supplied by a source only ensure that the total supplied power, which is the sum of the powers supplied to the individual components of the motor vehicle, does not exceed a maximum value specific for the source.

[0009] Figure 1 schematically shows a power source S configured to supply a plurality of M users of a vehicle. An electronic control unit E may be installed on board the vehicle in order to manage (i.e. allocate, distribute) the power flow which can be supplied by the source S to the M users requesting it.

[0010] The power source S shown in Figure 1 may be e.g. a battery (or battery pack) installed on board a vehicle with (at least partly) electric traction, and configured to supply (e.g. high-voltage) electric power in order to power the M users of the vehicle.

[0011] The users of the vehicle may comprise, for example: the motors of the vehicle, the heating / cooling of the battery, the heating / cooling of the cabin, and low-voltage auxiliary users (automotive lamps and / or lights installed in the cabin of the vehicle, for example).

[0012] The power supplied by the battery S is allocated to the users in such a way that the total power supplied by the source S does not exceed a given threshold value. Such a threshold value may be due to operational limits of the battery S, and the request to supply a power greater than said threshold value may damage the battery and / or cause the interruption of the supply (opening of the contacts) in order to protect the battery.

[0013] According to a conventional approach, the total power suppliable by the source S may be allocated by determining, for each user, a maximum amount of absorbed power, expressed as a fraction of the total power suppliable by the source S.

[0014] For example, the case may be considered wherein the total power suppliable by a battery S (for example, 500 kW) is allocated to two users, for example the motors of the vehicle and the conditioning (heating or cooling) of the cabin of the vehicle.

[0015] The total power is therefore distributed by allocating a maximum to the power which can be absorbed by the motors (for example, 480 kW) and a maximum to the power which can be absorbed by the conditioning of the cabin (20 kW).

[0016] Such a "static" power allocation, although it (at least notionally) eliminates the risk of overloads of the source S, may reveal itself as disadvantageous or inefficient. Considering the example in the foregoing, if the conditioning of the cabin requires less power than the maximum allocated thereto (for example 10 kW out of 20 kW), the residual power is anyway inaccessible by the other users (in the present example, by the motors).

[0017] Object of the Invention

[0018] The object of the invention is to solve the technical problems outlined in the foregoing. Specifically, the invention aims at managing the allocation of the power suppliable by a source in an effective way.

[0019] Summary of the Invention

[0020] The object of the invention is achieved by a method having the features set forth in the claims that follow, which are an integral part of the technical teaching provided herein in relation to the invention.

[0021] In solutions such as described herein, the users are ordered according to a priority order, which is preferably variable in time. Such a priority order reflects the fact that, in given driving conditions (or, generally, in given usage conditions of the vehicle), or due to a choice by the vehicle driver, it is desirable to determine the maximum of the power absorbable by each user according to a priority order, thus satisfying (when it is possible) the power requests of the users having higher priority by limiting, if possible, the power supplied to the users having lower priority.

[0022] In solutions as described herein, the total power suppliable (or absorbable) by a source is allocated to the various users by defining maxima of power that can be absorbed (or supplied) by each user.

[0023] In solutions as described herein, such maxima are calculated at every time instant based on the priority order of the users and as a function of the power absorbed (or supplied) by each user.

[0024] Brief Description of the Figures

[0025] The invention will now be described with reference to the annexed Figures, which are provided by way of non-limiting example only and wherein:

[0026] - Figure 1, already described in the foregoing, schematically shows a source powering a plurality of users of a vehicle,

[0027] - Figures 2A and 2B show possible applications of solutions according to embodiments of the present description, and

[0028] Figures 3A to 3D and 4A to 4D are diagrams exemplifying possible applications of a method according to embodiments of the present description for allocating the power suppliable by a source to users of a vehicle.

[0029] Detailed Description

[0030] In the following there will be described a method for allocating the total power suppliable by a source to a plurality of M users of a vehicle. A merely exemplary list of users has already been provided in the foregoing.

[0031] It will be noted that, although two or more users may be managed by one and the same component, it is convenient to consider the power requests relating to each user as separate and distinct. For example, a single hardware component (an "e-coolant heater", ECH) may be configured for both heating the cabin and heating the battery; in this case, the requests of power for heating the battery and for heating the cabin of the vehicle may be treated as distinct power requests (and therefore as distinct users). Similarly, one and the same component (a compressor such as an "e-air compressor", EAC, for example) may be used for cooling the cabin of the vehicle and for cooling the battery; also in this case, the power requests from one and the same component may be treated as power requests from distinct users.

[0032] On the contrary, low-voltage auxiliary users (for example the car lamps and / or the lights provided in the cabin) may be treated on the whole as a single user, since they are powered by the battery S only via a (DC- DC) converter; the power requests from the low-voltage users are "seen" by the electronic control unit E, as a whole, as a (single total) power request from the converter.

[0033] Figures 2A and 2B schematically show possible applications of solutions according to embodiments of the present description.

[0034] Figure 2A shows, as in the example discussed above, a battery installed on a vehicle V, which is used as a power source S configured to power a set of users 1, 2, 3 of the motor vehicle V.

[0035] Figure 2B shows another possible application, wherein a vehicle V is not moving and is connected to a charging station. In such a situation, the charging station may be considered as the power source S, configured to supply power which may be used to recharge the battery of the vehicle V (which in this case is therefore considered as a user) and to supply the further users of the vehicle V.

[0036] Considering the possible applications described in the foregoing, in the following we will deal, more generally, with a source S (battery, charging station) configured to power a set of M users, each having a respective power request RN. The power requests RNmay vary in time; for example, the electric motor (s) may require a power which varies as a function of the acceleration desired by the driver of the vehicle. As a further example, we may consider the power request by the battery conditioning system, which may vary as a function of the temperature of the same batteries.

[0037] As already mentioned in the foregoing, according to an aspect of the invention the M users may be ordered according to a priority order.

[0038] The priority order of the M users may depend, for example, on the particular driving mode selected by the driver of the vehicle. In a competitive driving mode, for example, the priority order of the users would assign a higher priority to the motors.

[0039] It is also possible to consider the exemplary case wherein the vehicle is driving in a cold environment; in this case, a higher priority will be given to the users configured to heat the cabin (and / or to defrost the windshield) and / or to heat the battery.

[0040] As a further example, it is possible to consider a vehicle stationed at a charging station (as exemplified in Figure 2B) in the case a fast charge mode has been selected: in such an instance, the battery (considered as a user) will be assigned the highest priority.

[0041] The cases discussed in the foregoing are merely (non-limiting) exemplary of possible usage modes of the vehicle, which may correspond to different orderings of the M users based on the priority thereof.

[0042] As will be further discussed in the following, each usage mode of the vehicle will correspond not only to a given priority order of the M users, but also to a set of parameters corresponding to the usage mode of the vehicle.

[0043] Once a desired priority order has been defined, it is possible to identify, for each N-th user: a first set of users, comprising the 1stto the (N- l)-th users having higher priority than the N-th user, and a second set of users, comprising the (N+l)-th to the M-th users having a lower priority than the N-th user.

[0044] Such sets are defined at every time instant, based on the priority order of the users, which in turn depends on time.

[0045] Subsequently there is defined, for each N-th user in the plurality of the M users, a maximum value of the power absorbable by the N-th user. M maximum values are thus obtained, defined as a function of: : the total power suppliable by the source S at the time instant t; the powers absorbed by the users at the time instant t; : power reserves of the users at the time instant t; and . power reserve parameters of the users, which parametrize the power reserves ()

[0046] The reserve parameters are positive or zero, and they may depend on the driving or usage mode of the vehicle. Each driving / usage mode of the vehicle corresponds to a set of parameters

[0047] In the following, the dependence on time of the various values will not be explicitly indicated, in order not to overburden the notation used.

[0048] Moreover, as it is obvious to a person skilled in the art, the instant values listed in the foregoing and described in the following part of the description are to be construed as values measured / sampled at proper time intervals.

[0049] An object of the invention is thus a method for allocating the available power suppliable by a source S to a plurality of M users of a vehicle V.

[0050] The method comprises defining a priority order of the M users that identifies, for each N-th user in the plurality of M users, a first set comprising the 1stto the (N-l)-th users having a higher priority than the N- th user, and a second set of users comprising the (N+l)- th to the M-th users having a lower priority than the N- th user.

[0051] Subsequently, the method comprises defining, for each N-th user, a maximum value for the power absorbable by the same user as a function of the available power , a power absorbed by each of the users of the second set, a power reserve for each of the users of the second set, a power absorbed by the users of the first set, a power reserve for the N-th user wherein said power reserve for the N-th user is in turn defined as a function of said available power said power absorbed by each user of the second set, said power reserve B^esfor each of the users of the second set, a power reserve parameter predetermined for each of the users of the first set and a power reserve parameter predetermined for the N-th user.

[0052] The available power suppliable by the source (S) is allocated by imposing that, for each N-th user, the power absorbed by the N-th user must be less than or equal to the maximum value defined for that user

[0053] As will be described in the following, a method as described herein may advantageously be applied also in such cases wherein the power suppliable by the source and the power absorbed by the users are negative or zero values, i.e.

[0054] Generally speaking, therefore, the method comprises defining, for each N-th user, a maximum (positive) value of the absolute value of the power absorbable by the user; it is therefore imposed that, for each N-th user, the absolute value of the power absorbed by the N-th user must be less than or equal to the maximum value defined for the same user

[0055] In one or more embodiments, the maxima may advantageously be defined by means of an analytic expression.

[0056] In one or more embodiments, the power suppliable by the source and the power absorbed by each N-th user are positive values, i.e. and In this case, the maxima may be expressed by means of the expressions:

[0057] Wherein the second equation defines the power reserve . The maximum function contained in the definition of (expression (2)) leads to be defined as positive for each (positive) value of the parameters if B is the function and B+is its positive part, i.e.

[0058] B+= max{B,0} the expression (2) may be rewritten as

[0059] The person skilled in the art will appreciate that, for the purpose of calculating the maximum values it is equivalent to define the power reserves by means of the function B or by means of the positive part B+thereof as stated in the foregoing, the definition of given in the expression (2) is advantageous, since the power reserve thus defined is positive for any value of the reserve parameters

[0060] As will be apparent from the examples described in the following, the equations (1) and (2) define two operation modes, the former being an optimal operation mode and the latter being a reserve operation mode, wherein the maximum value is obtained from the expressions (1) and (2), respectively.

[0061] It will be noted that the maxima are properly defined by the equations (1) and (2). In order to highlight this aspect, it is to be considered that it is possible to calculate the maxima starting from the expression of the value of the power reserve for the user M having the lowest priority (expression 2)). Indeed, for such user M the expression (2) simply implies the evaluation of the minimum value between the reserve parameter of the user and the value obtained by subtracting, from the total suppliable power the sum of the reserve parameters performed on the set of the user having a higher priority j=1,...,M-1. It is then possible to evaluate for which it is necessary to evaluate the minimum between the power absorbed by the user M and the maximum reserve value which is evaluated as described in the foregoing. Similarly, it is possible to evaluate the maximum reserve values for the remaining users, thereby obtaining the M values for the power reserves which are involved in the equation (1) for calculating the maxima

[0062] It is easy to verify (for example, starting from the expression (1)), that the maxima as defined above are non-negative

[0063] Moreover, it is possible to appreciate, for example from the expression (1), that the set of users having higher priority and with lower priority with respect to a given N-th user are considered in a different fashion for the definition of the maximum value In fact, in the expression (1) the users having higher priority are involved by means of the values of the absorbed power while in the expression (2) of the maximum reserve value they are involved by means of the reserve parameters

[0064] On the other hand, the users having lower priority are involved in the expressions (1) and (2) through the summation, performed on the users having lower priority, of the minimum between the value of the power absorbed by the user and the maximum reserve value of the same user.

[0065] It will be understood that it is the minimum function present in the expressions (1) and (2) which makes accessible, to the users having higher priority, the power which is not employed by the users having lower priority. In order to highlight this aspect, it may be considered the extreme case wherein no user requires or absorbs power, i.e. for any N from 1 to M. It is easy to verify, starting from the expressions (1) and (2), that in this extreme case any user is enabled to access the whole available power, i.e.

[0066] A further advantageous feature of the maxima defined by the expressions (1) and (2) resides in the fact that, if all the powers absorbed by the users equal the respective maximum defined by the expressions (1) and (2), then the sum of the maximum powers of the M users equals the total power suppliable by the source S, i.e., expressed in formulae:

[0067] Said property may be verified in the simple case of two users N=l,2 for which holds true.

[0068] From this assumption, therefore, and the expressions (1) and (2) take on the form

[0069]

[0070] From the first two equation there follows, for the first user N=1 (the user having the highest priority)

[0071] Wherein the last equality derives from the fact that, for any value the following holds

[0072] By inserting the relation into the expression for it is possible to obtain

[0073] Similarly, it is possible to verify the property set forth in the general case of M users thanks to the considerations that follow.

[0074] A further advantageous property of the maxima defined by means of the expressions (1) and (2) (or the expressions (3) and (4) described in the following) resides in the fact that, if the power absorbed by the N-th user, with N being different from M, equals the first term in the maximum function of the expression (1) of the corresponding maximum power, then the following three conditions are equivalent:

[0075] (a) the sum of the powers absorbed by the M users equals the total power suppliable by the source S;

[0076] (b) the powers absorbed by the i>N users are less than or equal to the respective power reserves defined by the expression (2);

[0077] (c) the power reserves, which are defined by the expression (2) for each user of the i>N users (i.e., the users having a lower priority than the N-th user) equal the respective maximum powers defined by the expressions (1)-(2).

[0078] Expressed as formulae: if for the user N the following holds true, then

[0079] In order to highlight the implication (a)=>(b) it may be noted that, in the assumptions made, it is possible to write, for the total power suppliable by the source S Whence the property (b) follows, since the values are defined as positive.

[0080] The opposite implication, i.e. (b)=>(a), derives from the fact that, assuming that (b) is starting from the expression assumed for the following holds true:

[0081] In order to highlight the implication (b)=>(c), let us consider the power absorbed by each of the users having a lower priority than the user N, i.e. let us consider the value for each k = 1,...M — N,

[0082] The first term of the maximum function in the expression set forth above may be rewritten, by taking into account the assumption made for and the condition (b), as follows:

[0083]

[0084] It is then possible to rewrite the expression (1) for the maximum power defined for the user N + k, for any k = — N, i.e., the property (c). It is to be noted that the last equation derives from condition (b).

[0085] Finally, assuming the property (c) as true, the following is derived: starting from the expression assumed for , the property (a) follows directly, and therefore the implication (c)=>(a) holds true.

[0086] Similarly, it is possible to demonstrate a sort of reversed result, i.e., more precisely, it is possible to demonstrate that, if the condition (a) holds true, i.e. the sum of the powers absorbed by the M users equals the total power suppliable by the source S, and one of the conditions (b) and (c) on the reserved powers defined by the expression (2) for the users i> N, then the power absorbed by the user N is equal to the first term in the maximum function of the expression (1) of the corresponding maximum power.

[0087] It will be appreciated that such results hold true irrespective of the total power suppliable by the source S. Another advantageous property resides in the fact that, if the total power suppliable by the source S is greater than the sum of the power reserve parameters of the M users, the power reserve defined for an N-th user equals the corresponding power reserve parameter no matter which N it is.

[0088] As a formula, if

[0089] Then

[0090] Indeed, starting from the first term of the minimum function of the expression (2) for the N-th user, it follows that since for i> N + 1, because by definition.

[0091] Under the assumptions of the previous result, it is moreover possible to demonstrate that, if the condition (a) holds true, i.e. if the sum of the powers absorbed by the M users equals the total power suppliable by the source S, and one of the conditions (b) and (c) on the reserved powers defined by the expression (2) for the users i> N , then there is a user k ≤ N the absorbed power whereof equals the maximum power, and such maximum power is greater than the reserve parameter of the corresponding reserved power.

[0092] Expressed in formulae, if and

[0093] (or, in an equivalent way,

[0094] Then, there is a user k ≤ N for which the following holds true:

[0095] Considering the first term of the maximum function of the expression (1) for the N-th user, and simplifying it according to the condition (b) (or, in an equivalent way, according to the condition (c)), it follows that

[0096] Wherein the last equality derives from the condition (a). If in the hypothesis that , then the N-th user joins the users from the N + 1th to M, and this result can be demonstrated for the user k = N — 1, and so on. Since we are in the condition while proceeding towards k ≤ Nth users having higher priority, a user will necessarily be met for which this result is verified. Indeed, noting that and if holds true, due to the condition (b), then necessarily

[0097] If the previous result is applied to the user N = 1 (i.e. the user having the highest priority), then the equality may be demonstrated analytically as follows. Indeed, if the condition (b) (or, in an equivalent way, the condition (c)) holds true, then and the expressions (1) and (2) simply become

[0098] Whence it is possible to obtain the value for the user N = 1 (i.e., the user having the highest priority)

[0099] Wherein the latter relationship holds true thanks to the condition

[0100] In the specific case wherein the powers absorbed by the users i> N equal the reserve parameters of the respective absorbed powers, then the behaviour becomes clear of the priority mechanism highlighted in the Figures 3A-3D and discussed in the following. A further advantageous property of the maxima defined as described in the foregoing resides in the fact that, if the total power suppliable by the source S is lower than the sum of the power reserve parameters of the users j≤ N , then the reserved powers defined by the expression (2) of the users i>N are zero.

[0101] Expressed as formulae, if

[0102] Then

[0103] In order to demonstrate this result, it is sufficient to notice that with k >≥1, the values being defined as positive values. Considering the expression (2) for the user set forth below it is possible to notice that the first term of the maximum function is less than or equal to zero, since is defined as positive.

[0104] Under the assumptions of the previous result, it is possible to demonstrate that, if the condition (a) holds true, i.e. if the sum of the powers absorbed by the M users equals the total power suppliable by the source S, and one of the conditions (b) and (c) on the reserved powers defined by the expression (2) for the users i> N, then the power absorbed by the N-th user is less than the respective power reserve parameter, decreased by the difference between the sum of the power reserve parameters of the users i< N and the sum of the respective absorbed powers.

[0105] Expressed as formulae, if and

[0106] Or, in an equivalent way, then,

[0107] If the conditions (a) and (b) (or, in an equivalent way, c)) hold true, then it is possible to demonstrate that

[0108] Given the hypotheses, the thesis is demonstrated by showing that the following inequality holds true: In the particular instance wherein the powers absorbed by the users i< N are less than or equal to the respective reserved powers, the behaviour of the priority mechanism, as highlighted in the Figures 3A-3D, becomes clear.

[0109] In one or more embodiments, it is possible to allocate (limit) the power absorbable by the users by limiting the current supplied thereto. In this case, it is therefore convenient to express all the power values described in the foregoing with a corresponding current value indicative of the corresponding power value. For example, it may be convenient to determine - according to expressions very similar to (1) and (2) - a maximum current which can be absorbed by the battery of the motor vehicle when the latter is stationary and connected to a charging station.

[0110] Expressing the values of power with corresponding values of current may be advantageous, for example, in the situation shown in Figure 2B, wherein the power source S is a charging station which can supply a direct current.

[0111] In such cases, therefore, it may be advantageous to express the values of power with corresponding values of current, i.e.: expressing the available power Bavlwith a corresponding value of available current (for example, the total current suppliable by the charging station), expressing, for each N-th user, the power absorbed by the N-th user with a corresponding value of current absorbed by the N-th user, expressing, for each N-th user, the power reserve of the N-th user with a corresponding value of current reserve of the N-th user, expressing, for each N-th user, the power reserve parameter of the N-th user with a corresponding current reserve parameter of the N-th user.

[0112] It is then possible to define the maximum values of the current which can be absorbed by each user by means of the expressions (1) and (2), for example, wherein the powers are all expressed with corresponding current values.

[0113] In other words, for each N-th user the maximum value of power absorbable by the N-th user is expressed with a corresponding value of maximum current absorbable by the N-th user.

[0114] As mentioned in the foregoing, it may be useful to consider the case wherein the power Bavlsuppliable by the source S and the power absorbed by the M users are values less than or equal to zero.

[0115] Considering negative values for the power Bavlsuppliable by the source S and the power absorbed by the users may be useful, for example, when the electric motors of a vehicle V are configured to operate in the so-called regeneration mode, i.e. when the electric motors of the vehicle are configured to convert the mechanical power (if the vehicle V is braking or if the vehicle V is travelling downhill) into electric power, which may be employed for recharging the battery and / or for powering the vehicle components (EAC, ECH, DC-DC converter, for example).

[0116] The power generated by the electric motors in the regeneration mode may be summed with power contributions which may be obtained from the conversion into electric energy of the rotational energy of an axle of the vehicle, after decoupling the latter. Although the conversion of mechanical energy into electric energy is actually performed by the same component (i.e. by the electric motors), it may be convenient to consider the two contributions as two distinct users, which generate an electric power which may be absorbed by a source (i.e., the battery and the other components of the vehicle) .

[0117] The maximum electric power which can be absorbed by the battery and by the vehicle components is the sum of the powers absorbed by the components and of the maximum power which can be absorbed by the battery (the latter being a value which may depend on the battery specifications) .

[0118] In this case, it is possible to identify the contributions of power generated by the motors with users which absorb a negative power (i.e., which supply power) and to identify the battery and the vehicle components as a source having a negative suppliable power Bavl(i.e. the power absorbable by the battery and by the components) .

[0119] Whatever the specific application (whereof the instance described in the foregoing represents a possible example), it is therefore advantageous to be able to apply a method as described in the foregoing also in the case wherein the power Bavlsuppliable by the source S and the powers absorbed by the users are values which are defined as negative, i.e. 0.

[0120] It is possible to generalize the expressions (1) and (2) of the maxima in such a way as to admit negative values for B

[0121] It is therefore possible to define maximum values by means of the expressions:

[0122] wherein are predetermined non-negative parameters .

[0123] It should be noted that the values and defined by the expressions (3) and (4) are greater than or equal to zero by definition.

[0124] Once the maxima have been defined, it will be possible to limit the power (if possible, defined as negative) absorbed by each N-th user, by imposing

[0125] It will be appreciated that the expressions (3) and (4) are completely equivalent to the expressions (1) and (2) if (i.e., the source supplies power) and 0 (i.e. the users absorb power).

[0126] The person skilled in the art may moreover appreciate that the properties outlined in the foregoing, considering the expressions (1) and (2) of the maximum values , hold true even when considering the expressions (3) and (4) for the maximum values

[0127] To sum up what has been set forth in the foregoing, in one or more embodiments the maximum values of power may be defined by an analytical expression. Defining the maxima therefore comprises selecting, for each N-th user, the maximum value among:

[0128] - a value obtained by subtracting, from the absolute value of the available power the absolute value of the power absorbed by the users of the first set, and further subtracting, for each i-th user of the second set, the minimum between the absolute value of the power absorbed thereby and the reserve power of the same; or

[0129] - the power reserve of the N-th user; or

[0130] - zero.

[0131] Similarly, it is possible to define analytically also the power reserve B as the minimum between: the positive part of a value obtained by subtracting, from the absolute value of the available power , the predetermined power reserve parameter each of the users of the first set, and further subtracting, for each i-th user of the second set, the minimum between the absolute value of the power absorbed thereby and the reserve power of the same; and

[0132] - the predetermined power reserve parameter for the N-th user.

[0133] In order to illustrate a possible application of a method as described herein, it is possible to consider the exemplary case of a vehicle V having a battery, an electric motor and a further component (for example, an EAC for the cabin conditioning) installed on board.

[0134] If is the power absorbed by the motor, it may be assumed by convention that is positive when the electric motor absorbs power (in the propulsion mode) and that is negative when the electric motor generates power (in the regeneration mode).

[0135] Similarly, it is possible to define the power supplied by the battery which is conventionally defined as positive when the battery supplies power, and as negative when the battery absorbs power. The power which can be supplied or absorbed by the battery may depend on the state of charge and / or on the battery specifications. Generally, for wherein is the maximum power which can be absorbed by the battery, and is the maximum power which can be supplied by the battery.

[0136] Finally, the power absorbed by the component may be defined as Pcom> 0.

[0137] In the propulsion mode, the available power which can be supplied by the source is represented by the total power which the battery can supply

[0138] The power absorbed by the users of the vehicle in the traction mode comprises by the power absorbed by the motor and the power absorbed by the further component, therefore

[0139] Wherein is the positive part of

[0140] The traction mode will be characterized, moreover, by respective reserve (non-negative) parameters which are predetermined (for example in the calibration step).

[0141] By means of the expressions (3) and (4) it is possible to determine the maximum values for the traction mode and to limit the power absorbed by the user by imposing, for example via a control unit configured to the purpose, that

[0142] In the regeneration mode, the available power suppliable by the source is represented by the maximum power which can be absorbed by the battery and by the users, i.e.

[0143] The users in the regeneration mode only comprise the motor used in the regeneration mode, for which the absorbable power is less than or equal to zero, and it is possible to write

[0144] Wherein is the negative part of conventionally defined as

[0145] The regeneration mode will be characterized, moreover, by the (non-negative) reserve parameter which is predetermined (for example in the calibration step).

[0146] By means of the expressions (3) and (4) it is possible to determine the maximum values for the regeneration mode and to limit the power absorbed by the users, by imposing that

[0147] It should be noticed that, in the simple case described herein, wherein only one user can generate power, the last condition is equivalent to

[0148] The Figures 3A to 3D are diagrams showing possible applications of a method for determining the maximum power which can be absorbed by each user in a set of three users 1, 2, 3. For simplicity, it is assumed the case wherein the power suppliable by the source and the power absorbed by the three users are positive, i.e. . As a consequence, in the following reference will be made to the expressions (1) and (2) for the definition of the maximum powers.

[0149] The diagram of power vs. time in Figure 3A shows: three curves describing the absorbed power as a function of time by the three users (N=l,2,3), the total power absorbed by the users, defined as the sum of the absorbed powers, i.e. and the total power suppliable by the source S, B

[0150] The decreasing trend of the curve shown in Figure 3A may be an example, for instance, of a battery S of an electric traction vehicle which supplies a maximum power which decreases as the state of charge of the battery diminishes.

[0151] The Figures 3B, 3C and 3D show, for the users 1, 2 and 3 respectively: the power RNrequested by the user N; the maximum reserve power calculated by means of the expression (2); the maximum power calculated by means of the expression (1); and the absorbed power

[0152] In the example shown, the three users have a power request which is constant in time. Moreover, the three users are ordered according to a priority order 1, 2, 3, wherein the user 1 is the user having the highest priority and the user 3 is the user having the lowest priority.

[0153] As shown, the total suppliable power is more than the total power absorbed by the three users in the time interval T<T1; in this time interval, the maxima are (strictly) greater than the requests which can therefore be satisfied simultaneously

[0154] It should be noticed that in this time interval the maximum reserve values of the users coincide with their respective reserve parameters

[0155] At the time instant t1the total suppliable power equals the total absorbed power As a consequence, the power used by the various users will be limited (for example by means of an electronic control unit E), in order to avoid damaging the source (for example by causing an overload): specifically, as shown in Figure 3D, the maximum power of the user 3 (i.e. the user having the lowest priority) equals the power requested by the user at the instant t1, i.e. B for t=t1, and it is lower in the following time interval, i.e. for t1<t<t2. The power absorbed by the user 3 is therefore limited by imposing it to be smaller than the maximum calculated by means of the equation (1). It will be appreciated that, in the time interval from t1to t2, only the request having the lowest priority R3is limited, while the requests R1R2having a higher priority are met (i.e., , R=1,2).

[0156] The maximum power of user 3 is reduced until it reaches a value equalling the reserve parameter of the user 3, at the time instant t=t2. As discussed in the foregoing, the user 3 enters the reserve mode from the equation (1)), and the maximum power which can be absorbed thereby will not be limited further until the users 1 and 2 having higher priority in turn enter the reserve mode.

[0157] Thereafter, the power absorbed by the other users will be limited following an order of decreasing priority.

[0158] Specifically: the maximum power of the user 2 (and therefore the absorbed power is reduced from the requested value R2to the value of the reserve parameter in the time interval between t2and t3, and the maximum power of the user 1 (and therefore the absorbed power is reduced from the requested value R1to the value of the reserve parameter in the time interval between t3and t4.

[0159] At the instant t4 the three users are in the reserve mode . The further reduction of the total available power therefore leads to the reduction of the maximum power of the user having the lowest priority and, therefore, of the power absorbed by the same user

[0160] Once the minimum value (for t=t3) for the maximum power of user 3, i.e. is reached, the other users are further limited in an order of increasing priority, until the zero values are reached, for t=t6and for t=t7.

[0161] The instance exemplified in the Figures 3A to 3D shows that the value of the maximum power for each user initially decreases to a reserve level (parametrized by the reserve parameter for the users having lower priority. Starting from the instant when all the users are in the reserve mode, the maximum values further decrease, always in the order of increasing priority, until they reach the minimum value, i.e. zero.

[0162] The Figures 4A to 4D show diagrams similar to those of Figures 3A to 3D, representing another example wherein embodiments of the present description are applied in order to allocate the power supplied by a source to three users 1, 2, 3. The values shown in the diagrams, as well as the notation used to refer to the same, are completely similar to what has been described in relation to the Figures 3A to 3D, and will not be discussed again herein.

[0163] In the example shown in the Figures 4A to 4D, the priority order is modified at a given instant t=t2. Specifically, the priority order shifts from {1,2,3} for t<t2to {3,1,2} for t>t2. Such a modification of the priority order of the users may be exemplary, for instance, of the occurrence of an acceleration manoeuvre for which it is desirable to assign a higher priority to the electric motors. In this exemplary case, the users 1, 2 and 3 may respectively represent the auxiliary loads (user 1), the cooling of the battery (user 2) and the electric motors (user 3). At the beginning of the acceleration manoeuvre (for t=t2), the motors shift from low priority (priority order {1,2,3}) to high priority (priority order {3,1,2}).

[0164] In brief, in the example shown in the Figures 4A to 4D: - (t<t1) The maximum values calculated for each user are greater than the requests, and therefore

[0165] - (t=t1) The request of the user 3 having the lowest priority equals the maximum calculated value,

[0166] - (t1<t<t2) The power absorbed by the user 3 decreases due to the reduction of the maximum power.

[0167] - (t=t2) The priority order is modified, from {1,2,3} to {3,1,2}, and thus the user 3 becomes the user having the highest priority; the maximum values are then recalculated as a function of the new priority order (as can be seen in the Figures 4B, 4C and 4D, wherein the curves which describe the maxima have a vertical section for t=t2).

[0168] - (t2<t<t3) The power absorbed by the user 2, i.e. the user 2, decreases due to the reduction of the maximum power, until it reaches its reserve level

[0169] The evolution of the curves for the times t>t3is completely similar to what has been described in the previous example, which makes it unnecessary to provide a more detailed description herein.

[0170] In one or more embodiments, it is possible to envisage further parameters for defining an upper limit of the maximum power of each user. Introducing such upper limits may be advantageous in such instances when the driver of the vehicle wants to impose a limit to the power supplied by the battery of the vehicle to a given user. For example, the driver may choose among different driving settings or modes, such as e.g. a driving mode which focuses more on the performances than on the maximum possible travelling distance (or vice versa), each mode corresponding to respective limits imposed to the power which may be absorbed by the motors. In another example, the driver may choose among various recharging options (e.g. rapid or normal charging) when the vehicle is connected to a battery charging station; such options may be implemented by imposing further upper limits to the power (or, in an equivalent way, to the current) which can be absorbed by the battery.

[0171] Moreover, upper limits for the power which can be absorbed by a user may be connected to the specifications of the (hardware) component dedicated to that user, which operates, e.g., below a given power value.

[0172] To this end, it is possible to introduce further (positive or zero) parameters for each N-th user, wherein: is an external upper limit for the N-th user (which may be set by the driver, for example), and is the hardware upper limit for the N-th user.

[0173] In one or more embodiments, it is possible to calculate the maximum values also as a function of the external and hardware upper limits, by means of the equations: wherein B is defined by the expression (4), which is reproduced here again for convenience.

[0174] It will be appreciated that: the maxima calculated by means of the equations (4), (7) and (8) reduce to the maxima calculated by means of the equations (3) and (4) in the limit of sufficiently high values of and , and the advantageous properties discussed for the maxima calculated by means of the expressions (3) and (4) keep on being valid also for the maxima calculated by means of the expressions (4), (7) and (8).

[0175] To sum up, in one or more embodiments the method comprises defining, for each N-th user, a maximum value of absolute value of the absorbable power which is also function of an external threshold power parameter which is predetermined for the N-th user, and of a hardware threshold power parameter which is predetermined for the N-th user.

[0176] In this case, defining for each N-th user said maximum value of the absolute value of the absorbable power comprises: a) evaluating the minimum value between:

[0177] - a value obtained by subtracting, from the absolute value of the available power the absolute power of the power absorbed by the users of the first set, and by further subtracting, for each i-th user of the second set, the minimum between the absolute value of the power absorbed thereby and the reserve power of the same, and

[0178] - the external threshold power parameter of the N-th user; b) evaluating the maximum value between:

[0179] - the minimum evaluated in step a), and

[0180] - the power reserve of the N-th user; c) evaluating the minimum between:

[0181] - the maximum value evaluated in step b), and

[0182] - the hardware threshold power parameter of the N-th user; d) defining the maximum value of the absolute value of the power absorbable by the N-th user as the maximum between:

[0183] - the minimum evaluated in step c), and

[0184] - zero.

[0185] If the powers are expressed through corresponding current values, in order to apply the expressions (4), (7) and (8) it will be necessary to: express, for each N-th user, the external threshold power parameter of the N-th user with a corresponding external threshold current parameter of the N-th user, and express, for each N-th user, the hardware threshold power parameter of the N-th user with a corresponding hardware threshold current parameter of the N-th user.

[0186] A method as described herein may be implemented, in a way per se known by the person skilled in the art, by means of a single electronic control unit E installed on board the vehicle V and configured to execute a method as described herein.

[0187] Once the electronic control unit E has detected a usage mode of the vehicle (a driving mode selected by the driver of the vehicle, for example), it is possible to define the priority order of the users and the parameters corresponding to the usage mode which has been detected / selected. For example, such parameters may be stored in a memory of the electronic control unit E.

[0188] The electronic control unit E may therefore be configured to calculate (at every instant) the maximum values defined by the equations (4), (7) and (8) (or by the expressions (3) and (4)), and to limit the absolute value of the power absorbed by each N-th user, so that holds true.

[0189] Without prejudice to the underlying principles, the details and the embodiments may vary, even significantly, with respect to what has been described by way of example only, without departing from the extent of the embodiments. The scope of protection is set forth in the annexed claims.

Claims

CLAIMS1. Method for allocating an available powersuppliable from a source (S) to a plurality of M users of a vehicle (V), comprising:- defining a priority order of the M users that identifies for each Nth user in the plurality of M users a first set comprising the 1st to the (N-l)-th users having higher priority than the N-th user and a second set of users comprising the (N+l)-th to the M-th users having a lower priority than the N-th user,- defining for each N-th user a maximum valuefor the absolute value of the power absorbable by the N- th user as a function of the available power a powerabsorbed by each user of the second set, a power reserve B of each user of the second set, a power absorbed by the users in the first set, a powerreserve of the N-th user , wherein said power reserveof the Nth user is defined as a function of said available power said power absorbed by by eachuser of the second set, said power reserveof each user of the second set, a power reserve parameterpredetermined for each user of the first set and a power reserve parameter predetermined for the Nth user,and- allocating the available powersuppliable by the source (S) by imposing that, for each N-th user in the plurality of M users, the absolute value of the power absorbed by the N-th user to be less than or equalto the maximum value defined for the N-th user2. The method according to claim 1, wherein said power reserveof the N-th user is defined by selecting the minimum between:the positive part of a value obtained by subtracting from the absolute value of the available powerthe power reserve parameterof each of the users of the first set, and further subtracting for each i-th user of the second set the minimum between the absolute value of the power absorbedby i-th user and the power reserve of the i-th user; and- the power reserve parameter predeterminedfor the N-th user.

3. The method according to claim 1 or claim 2, wherein said defining for each N-th user a maximum value for absolute value of the power absorbable bythe N-th user comprises selecting for each N-th user the maximum valuebetween:- a value obtained by subtracting from the absolute value of the available power the absolute value ofthe power absorbedby the users of the first set, and further subtracting for each i-th user of the second set the minimum between the absolute value of the power absorbed by the i-th user and the power reserveof the i-th user; or- the power reserve of the N-th user; or- zero.

4. The method according to claim 1 or claim 2, comprising defining for each N-th user a maximum value of the absolute value of the power absorbable bythe N-th user also as a function of an external threshold parameter predetermined for the N-th user and of ahardware threshold parameter predetermined for theN-th user, wherein said defining for each N-th user said maximum value of the absolute value of the powerabsorbable comprises:(a) evaluating the minimum between:- a value obtained by subtracting from the absolute value of the available powerthe absolute value of the power absorbed by the users of the first set,and further subtracting for each i-th user of the second set the minimum between the absolute value of the power absorbed by the i-th user and the reserve powerof the i-th user, and- the external threshold parameter of the N-thuser;(b) evaluating the maximum between:- the minimum evaluated in step (a), and- the power reserve of the N-th user;(c) evaluating the minimum between:- the maximum evaluated in step (b), and- the hardware threshold parameter of the N-thuser;(d) defining the maximum value of the absolutevalue of the power absorbable by the N-th user as the maximum between:- the minimum evaluated in step (c), and- zero.

5. Method according to any of the previous claims, comprising: expressing the available powerwith a corresponding value of available current, expressing for each N-th user the power absorbed by the N-th user with a corresponding value ofcurrent absorbed by the N-th user, expressing for each N-th user the power reserveof the N-th user with a corresponding value of current reserve of the N-th user, expressing for each N-th user the power reserve parameter of the N-th user with a correspondingvalue of current reserve parameter, expressing for each N-th user the external threshold parameterof the N-th user with a corresponding value of the external threshold current parameter of the N-th user,expressing for each N-th user the hardware threshold parameter of the N-th user with acorresponding value of hardware threshold current parameter of the N-th user, and expressing for each N-th user the maximum valueof the absolute value of the power absorbable by the Nth user with a corresponding maximum value of the absolute value of the current absorbable by the N-th user.

6. Method according to any of the previous claims, wherein: the available powersuppliable by the source (S) is greater than or equal to zero, andthe power absorbed by each N-th user in theplurality of M users is greater than or equal to zero,7. Method according to claim 6, wherein said plurality of M users of the vehicle comprises: one or more users configured for heating and / or cooling a battery installed in the vehicle, and / or one or more users configured for heating and / or cooling the cabin of the vehicle, and / or one or more low voltage auxiliary users.

8. Method according to claim 6 or claim 7, wherein said source (S) comprises a battery installed in the vehicle configured to power said plurality of M users of the vehicle, said plurality of M users of the vehicle comprising one or more electric motors, wherein saidbattery installed in the vehicle is configured to power said one or more electric motors.

9. Method according to claim 6 or claim 7, wherein said source (S) comprises a charging station external to the vehicle configured to power said plurality of M users of the vehicle, said plurality of M users of the vehicle comprising a battery installed in the vehicle, wherein said charging station is configured for supplying power to said battery installed in the vehicle.

10. Method according to any of claims 1 to 5, wherein: the available power suppliable by the source(S) is less than or equal to zero,and the power absorbedby each N-th user in the plurality of M users is less than or equal to zero, 0.

11. Method according to claim 10, wherein said source (S) comprises a battery and one or more components installed in the vehicle configured for absorbing power generated by the plurality of M users of the vehicle, said plurality of M users of the vehicle comprising one or more electric motors configured to operate in regeneration mode by absorbing mechanical power and generating electrical power, said one or more electric motors being installed in the vehicle and being configured for supplying power to said battery and said one or more components installed in the vehicle.

12. Vehicle (V), comprising: a plurality of M users, and an electronic control unit (E), wherein said electronic control unit (E) isconfigured for executing a method according to any of the claims 1 to 11 for allocating an available powersuppliable by a source (S) to said plurality of M users of the vehicle (V).

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