Method of determining the energy consumption of an electric vehicle, corresponding system, vehicle and computer program product
By accounting for all energy transfers and consumption types, the method improves the accuracy of energy consumption and residual range calculations in electric vehicles, addressing the limitations of existing technologies and reducing driver anxiety.
Patent Information
- Application Number
- PCT/IB2024/060964
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-11-16
- Filing Date
- 2024-11-06
- Publication Date
- 2025-05-22
AI Technical Summary
Existing methods for determining the energy consumption of electric vehicles provide only approximate estimates, leading to inaccurate residual range calculations and increased driver anxiety due to fluctuations in range predictions.
A method that calculates the energy consumption of an electric vehicle by considering all energy transfers between the battery and the vehicle, including kinetic and potential energy, and non-propulsive consumption, using sensors to measure dynamic and electrical quantities.
This method provides a more accurate and stable estimate of energy consumption, resulting in a more precise residual range calculation that aligns with the vehicle's energy storage and current driving style, reducing driver anxiety.
Smart Images
Figure IB2024060964_22052025_PF_FP_ABST
Abstract
Description
[0001] “Method of determining the energy consumption of an electric vehicle, corresponding system, vehicle and computer program product”
[0002] * * * *
[0003] TEXT OF THE DESCRIPTION
[0004] Field of the invention
[0005] The present invention relates to a method and a system for determining the energy consumption of an electric-drive vehicle (Battery Electric Vehicle, BEV), a corresponding electric vehicle and a corresponding computer program product. The estimate of the energy consumption (expressed in unit of distance per unit of energy, e.g. km / kJ, similar to what is done for vehicles with a combustion engine, for which the consumption is usually expressed in km / l, that is, kilometers traveled per liter of fuel) can be used to determine the residual range of the vehicle (expressed in units of distance, e.g. km) that is displayed in the instrument cluster.
[0006] Prior art
[0007] A known method for estimating the energy consumption C (in km / kJ) of an electric vehicle (BEV) involves measuring the net amount of energy Ed that has been drawn from the battery (here meaning the high-voltage traction battery, and not the 12 V auxiliary battery) during a stretch of road having a certain predetermined length d, and simply dividing the distance d by the net energy Ed, according to the following equation:
[0008] For example, the distance d may be equal to 5 km. The net energy Ed can therefore be measured or computed at a determined time by integrating, in the time domain, the net electric power supplied by the battery during the last 5 km traveled by the vehicle. Here we speak of “net energy” drawn from the battery and “net electric power” supplied by the battery because, in modem electric vehicles, there are regenerative systems that recover energy (e.g., during braking of the vehicle) to recharge the battery. Therefore, the net energy Ed is computed as the sum of the energy drawn to provide traction to the vehicle and the energy drawn to power the vehicle’s auxiliary systems (e.g., the air conditioning system of the vehicle cabin, the heating / cooling system of the battery, and all other electrical systems powered by the high-voltage battery), minus the energy recovered during braking by the regenerative energy recovery systems.
[0009] Once the energy consumption C (in km / kJ) has been computed according to the previous equation, filtering algorithms can be applied to “smoothen” the oscillations of the consumption value C and produce a consumption value Csmooth (also expressed in km / kJ). After this filtering operation, the residual range R (in km) can be computed by multiplying the residual energy stored in the high-voltage battery by the consumption Csmooth-
[0010] The computation of the consumption values C and Csmooth, and consequently of the range R, can be repeated at regular intervals to update the value of the residual range displayed in the instrument cluster. For example, if the predetermined distance d is equal to 5 km, the computation can be updated every 20 km, every 10 km, every 5 km or even at shorter intervals.
[0011] This known solution, however, only provides an approximate estimate of the average energy consumption of the vehicle during a stretch of road with a predetermined length d. Therefore, the computation of the residual range R is also approximate, and in many cases it is not consistent with the driver’s driving style and can become unrealistic, except in the case of trips made in particularly stable conditions (e.g., motorway trips at a substantially constant speed and on a predominantly flat road). As a result, the residual range value R displayed in the instrument cluster may be subject to even significant fluctuations, which do not allow the driver to fully exploit the actual range of the vehicle by planning charging stops as best as possible, and generate the so-called “range anxiety” in the driver.
[0012] Therefore, there is a need to develop an improved method for determining the energy consumption of an electric vehicle, which is more accurate than known methods and consequently allows the residual range to be determined with greater precision and fewer fluctuations.
[0013] Object of the invention
[0014] The object of the present invention is to provide such an improved method for determining the energy consumption of an electric vehicle, as well as a corresponding system, a corresponding electric vehicle and a corresponding computer program product. At least part of the method can be implemented by an electronic processor. The method according to the invention allows to determine the residual range of the vehicle with greater precision, so that this is consistent with the energy stored in the vehicle and with the current (or in any case more recent) driving style of the driver.
[0015] Summary of the invention
[0016] According to an aspect of the present disclosure, the invention relates to a method for determining the energy consumption of an electric vehicle. The electric vehicle comprises a high-voltage traction battery, an electric motor and one or more auxiliary electric loads (i.e., non-propulsive, service electric loads). The method comprises the following steps: i) sensing the longitudinal speed (in particular, the instantaneous forward speed) of the vehicle, the (instantaneous) longitudinal acceleration of the vehicle, the mass of the vehicle, the power delivered by the electric motor of the vehicle for the propulsion of the vehicle, the power regenerated by the electric motor of the vehicle and transferred to the traction battery of the vehicle, the total power consumed for supplying the auxiliary electric loads, and the power regenerated by the electric motor of the vehicle and transferred to the auxiliary electric loads of the vehicle; ii) determining a first value of net power dissipated for the propulsion of the vehicle at a determined time, by subtracting the power regenerated by the electric motor of the vehicle and transferred to the traction battery of the vehicle and the product of the mass, longitudinal speed and longitudinal acceleration of the vehicle from the power delivered by the electric motor of the vehicle for the propulsion of the vehicle; iii) determining a second value of net power consumed for supplying the auxiliary electric loads of the vehicle at a determined time, by subtracting the power regenerated by the electric motor of the vehicle and transferred to the auxiliary electric loads of the vehicle from the total power consumed for supplying the auxiliary electric loads; and iv) determining the energy consumption of the vehicle by computing the ratio between the longitudinal speed of the vehicle and the sum of the first value of net power and the second value of net power.
[0017] As will be explained in greater detail in the description that follows, the main idea underlying the present invention is to compute the estimate of the energy consumption of the vehicle by considering all energy transfers between the battery and the vehicle itself (which stores kinetic energy and / or potential energy), and by considering all non-propulsive consumption (aerodynamic losses, friction, dissipation of the braking system, and consumption related to the electrical systems of the passenger cabin and of the vehicle in general), starting from the measurement of dynamic quantities of the vehicle (speed, acceleration) and electrical quantities (voltages, currents).
[0018] According to a further aspect of the present disclosure, the invention relates to a system for determining the energy consumption of an electric vehicle. The electric vehicle comprises a high-voltage traction battery, an electric motor and one or more auxiliary electric loads. The system comprises at least one speed sensor configured to sense the longitudinal speed of the vehicle, and a plurality of current and voltage sensors configured to sense the current and voltage sunk by the electric motor during traction of the vehicle, the current and voltage provided by the electric motor to the traction battery during regenerative braking of the vehicle, the currents and voltages sunk by the auxiliary electric loads, and the current and voltage provided by the electric motor to the auxiliary electric loads during regenerative braking of the vehicle. The system further comprises an electronic processing unit configured to receive data from the speed sensor and the plurality of current and voltage sensors, and further configured to carry out the method according to one or more embodiments.
[0019] According to a further aspect of the present disclosure, the invention relates to an electric vehicle comprising a high-voltage traction battery, at least one electric motor, and one or more auxiliary electric loads. The traction battery is configured to provide power to the auxiliary electric loads and to provide power to the electric motor during traction of the electric vehicle. During regenerative braking, the electric motor is configured to provide power to the traction battery and / or provide power to the auxiliary electric loads. The vehicle also comprises a system according to one or more embodiments. According to a further aspect of the present disclosure, the invention relates to a computer program product loadable in the memory of an electronic processing unit and comprising instructions that, when the program is executed by the electronic processing unit, cause the electronic processing unit to carry out the method according to one or more embodiments.
[0020] Detailed description of the invention
[0021] Further features and advantages of the invention will be apparent from the following description with reference to the attached drawings, provided purely by way of non-limiting example, in which:
[0022] - Figure 1 is a block diagram illustrating the energy transfers between different components of an electric vehicle; and
[0023] - Figure 2 is a diagram illustrating the trend over time of some signals and physical quantities during a determined time period of use of an electric vehicle, in particular: the use of the accelerator, the use of the braking system, the speed of the vehicle, the power delivered (if positive) or received (if negative) by the battery, and the sum of the propulsive and non- propulsive consumption.
[0024] In the figures attached hereto, corresponding parts are indicated with the same reference numbers.
[0025] As previously mentioned, one or more embodiments relate to an improved method for determining the energy consumption of an electric vehicle. The inventors have observed that the known algorithms for computing the energy consumption of an electric vehicle focus only on the net energy drawn from the high-voltage battery in a determined time period (or rather, over a determined distance travelled), without considering the physics of the vehicle as a whole. In particular, the known algorithms do not take into account the fact that the energy drawn from the battery is not necessarily consumed, but is transformed into kinetic energy and / or potential energy that is stored by the vehicle. The method according to the present invention therefore provides for computing an estimate of the instantaneous energy consumption (not averaged over time) of the vehicle that takes into account the energy transfers between the high-voltage battery (which stores chemical energy) and the vehicle itself (which stores kinetic energy and / or potential energy), and that takes into account all non- propulsive consumption such as aerodynamic losses, friction, dissipation of the braking system, and consumption related to the electrical systems of the passenger cabin and of the vehicle in general. Therefore, the method is based on the measurement, by means of appropriate sensors provided in the vehicle, of the current and / or voltage supplied by the battery, as well as the speed and longitudinal acceleration of the vehicle. In some cases, the mass of the vehicle can also be measured by means of appropriate sensors provided on the shock absorbers of the vehicle; otherwise, the mass can be estimated according to other algorithms (e.g., as a function of the acceleration of the vehicle), or it can be provided as a calibratable parameter.
[0026] By way of introduction to the description of the method according to the present invention, the energy transfers between the different components of an electric vehicle V are schematized in Figure 1. In particular, the electric vehicle V comprises a high-voltage battery B that stores a determined amount of chemical energy EBat, a set of auxiliary electrical loads L (e.g., service electrical loads) that sink power and dissipate energy for their operation (as better detailed below), and at least one electric motor M. The battery B can supply a determined power PBat2Load to the electrical loads L (battery output power). Similarly, the battery B can supply a determined power PBat2Trc to the electric motor M during traction (battery output power). During regenerative braking, the engine M works as a generator and can therefore supply a determined power PRgn2Bat to the battery B (battery input power) and / or a determined power PRgn2Load to the electrical loads L. The distribution between the power PRgn2Bat and the power PRgn2Load during regenerative braking is determined by the current charging conditions of the battery B, the power required by the loads L, and the power delivered during the regeneration by the engine M. Overall, the electrical loads L dissipate a power Pi_oad which is equal to the sum of PBat2Load and PRgn2Load (the “clouds” illustrated in Figure 1 represent the dissipative, i.e. non-recoverable, consumption). Still referring to Figure 1 , during traction of vehicle V the electric motor M delivers a power P-j-rc, which is transformed into kinetic energy EKin accumulated by vehicle V, while on the contrary during the regenerative braking the electric motor M transforms a part of the kinetic energy EKin accumulated by vehicle V into a power Ppgn, which can then be delivered to the battery B or to the loads L as seen previously, Ppgnbeing equal to the sum of PRgn2Bat and PRgn2Load. Still referring to Figure 1 , the kinetic energy E^n of vehicle V is partially dissipated during the mechanical braking of vehicle V (as indicated by the dissipated power PHBrk) and is also partially dissipated during the so-called “coast down”, i.e., the simple slowing down of the vehicle due to friction, even in the absence of braking action (as indicated by the dissipated power PcstDwn). Still referring to Figure 1 , the kinetic energy Enn of the vehicle V can be transformed into potential energy Epot when the vehicle V travels on an uphill road (positive slope angle a - see the power PKin2Pot in Figure 1 ), or on the contrary the potential energy Epot of the vehicle V can be transformed into kinetic energy EKin when the vehicle V travels on a downhill road (negative slope angle a - see the power Ppot2Kin in Figure 1 ).
[0027] The method for computing the residual range of the vehicle V is therefore based on the computation of two variables, namely the total energy available in the vehicle as a whole (given by the sum of the chemical energy EBat stored in the high-voltage battery B and the kinetic energy E^n and potential energy Epot of the vehicle itself) and the instantaneous consumption of the vehicle.
[0028] The method which is the subject of the present invention focuses in particular on the computation of the instantaneous energy consumption of the vehicle. In particular, K is defined as the instantaneous energy consumption expressed in unit of distance per unit of energy (e.g., km / kJ). The consumption K can be computed according to the following equation (1 ): where v(t) is the instantaneous speed of the vehicle, conspmp(t) is the instantaneous net power consumed for the propulsion of the vehicle, and consNoPmp(t) is the instantaneous net power consumed by other electrical systems of the vehicle. In particular, the power conspmp(t) is a contribution related to the driving style and considers the energy losses necessary for the movement of the vehicle, while the power consNoProp® is a contribution related to the energy losses due to the electrical systems of the passenger cabin and of the vehicle in general (e.g., lights, infotainment system, and the like). The power consNoPmp(t) is therefore consumed even when the vehicle is on but not moving. Since v(t), conspmp(t) and consNoPmp(t) are instantaneous quantities, the consumption K is also an instantaneous quantity and indicates the consumption at a determined time t.
[0029] Other useful definitions for better understanding the method which is the object of the present invention are those of the power sunk by the electric motor during traction, here indicated with P-prc, and the power delivered by the electric motor during regeneration, here indicated with PRgn. In particular, the power P-p-c is defined as the maximum value between zero and the electric motor power PeMot, and the power PRgnis defined as the opposite of the minimum value between zero and the electric motor power PeMot, as indicated by the following equations (2) and (3):
[0030] In this way, when the electric motor power PeMot is positive (traction) then PTI-C = PeMot and PRgn= 0, while when the electric motor power PeMot is negative (regenerative braking) then PTK = 0 and Ppgn= -PeMot (i.e., Ppgnremains positive).
[0031] In addition, the net power delivered by the high-voltage battery is here indicated with PBat. By “net power” it is meant that the power PBat is positive if it is supplied by the battery to the vehicle loads, while it is negative if it is supplied by the vehicle to the battery (during regenerative braking).
[0032] The formula for computing the propulsive consumption conspmp(t) is obtained starting from the equation of the longitudinal motion of the vehicle V, represented below as equation (4):
[0033] In equation (4), m is the mass of the vehicle V, a is the longitudinal acceleration, v is the longitudinal speed, PMrrc and PMpgnare respectively the mechanical traction and regeneration powers supplied by the propulsion system, PHBrk is the power dissipated by the mechanical / hydraulic braking system and PcstDwn is the power dissipated due to friction and aerodynamic resistance. It will be noted that in equation (4), as in the other equations that follow, the indication of the time variable t has been omitted only for simplicity, and it is understood that all the quantities indicated in these equations are instantaneous. Given the electrical architecture of the high-voltage system of the vehicle V - already illustrated with reference to Figure 1 - in which the battery B, the electric motor M and the electric loads L are coupled to each other, the power Ppgnproduced by the motor M during the regenerative braking flows firstly to the electric loads L to supply them, and secondly to the battery B to recharge it, so that - as discussed above - the total regenerative power Ppgncan be written according to the following equation (5):
[0034] PRgn ~ PRgn2Bat T PRgn2Load (5)
[0035] Furthermore, the power PRgn2Bat flowing from the electric motor M to the battery B can be defined as the opposite of the minimum value between zero and the net power delivered by the battery PBat, as indicated in the following equation (6):
[0036] In this way, when the power PBat delivered by the battery is positive then PRgn2Bat = 0 (i.e., if the battery provides output energy, there can be no energy flow from the engine to the battery at the same time), while when the power PBat delivered by the battery is negative then PRgn2Bat = -PBat (i.e., all the energy recovered by the electric motor during regeneration is transferred to the battery).
[0037] The power conspmp(t) dissipated for propulsion consists by definition of the sum of the losses due to aerodynamic resistance and friction PcstDwn, the losses due to the conversion between electrical energy and mechanical energy PE2M (in other words, the internal losses of the electric motor M), the losses due to mechanical / hydraulic braking of the vehicle PnBrk, and the losses due to powering the electric loads L via regeneration, which by definition represent an energy consumption PRgn2Load. Therefore, the power conspmp(t) dissipated for propulsion can be written according to the following equation (7), where again the time variable t has been omitted only for brevity:
[0038] COTLSprOp = PcstDwn T PttBrk T PE2M T ^RgnlLoad (7)
[0039] The conversion losses between electrical energy and mechanical energy PE2M can be written according to the following equation (8):
[0040] Using equations (5), (7) and (8), equation (4) can be rewritten as the following, as equation (9): m a V — Pfrc ~ PRgn2Bat ~ COTIS prOp (9)
[0041] Equation (9), together with equations (2) and (6), allows to measure the power conspmp(t) dissipated for propulsion by using measurements of physical quantities detectable by sensors installed on the vehicle V. In particular, the estimate of the power conspmP(t) dissipated for propulsion requires measuring the mass, acceleration and speed of the vehicle V, the power delivered by the electric motor M and the power consumed by the battery B. The mass m of the vehicle can be measured by accelerometers positioned on elements subject to vertical dynamic displacements, for example on the shock absorbers. Alternatively, if such sensors are not available on the vehicle, the mass m can be introduced into the algorithm as a calibratable parameter, or it can be estimated starting from other physical quantities by means of estimate algorithms known in themselves. The longitudinal acceleration a and the longitudinal speed v of the vehicle can be measured respectively by accelerometers and tachometers (speed sensors) mounted on the vehicle V; acceleration a, moreover, can be computed starting from the speed data v in the case in which the vehicle is not equipped with accelerometers. Finally, the power delivered by the electric motor M and the power consumed by the battery B can be measured by means of appropriate current and voltage sensors mounted on the electric motor and on the battery.
[0042] The power conspmp(t) dissipated for propulsion can therefore be computed according to the following equation (10):
[0043] COTLSprOp — Pprc— TH. 0, V — Pggn2Bat (10)
[0044] The main advantage that derives from the use of equation (10) instead of equation (7) is that by using equation (10) the power conspmp(t) dissipated for propulsion can be computed starting from physical quantities measured directly on the vehicle V, without the need to use any physical model of the vehicle V to estimate the quantities of interest, nor to calibrate such a model (which would instead be necessary in the case of equation (7) if one thinks, for example, of the need to model the dissipations PcstDwn due to friction and aerodynamic resistance, the dissipations PHBFK due to mechanical / hydraulic braking, and the dissipations PE2M due to the conversion between electrical and mechanical energies). It will be noted that equation (10) also takes into account the possible slope angle a (positive or negative, i.e. , uphill or downhill) of the stretch of road traveled by the vehicle and therefore takes into account the fact that, all other conditions remaining the same, consumption increases if the road is uphill and decreases if the road is downhill. This derives from the fact that the measurement of the acceleration a carried out by the accelerometer on board the vehicle is conditioned by the gravitational acceleration g in the manner indicated by the following equation (11 ): a =aa=o — g ' sin a (11 ) that is, the measured acceleration a is equal to the sum of the acceleration that would be experienced on a flat road (aa=o) plus the projection of the gravitational acceleration g in the direction of travel of the vehicle.
[0045] Therefore, as regards the power conspmp(t) dissipated for propulsion, it has been described how the method according to the invention allows it to be computed starting from data measured on the vehicle, without the need for modelling and / or calibration.
[0046] Turning now to deal with the power consNoProp(t) dissipated for reasons other than propulsion, it has already been anticipated that this corresponds to the power used to supply the auxiliary electrical loads, i.e., those that keep the high-voltage system active, those relating to the cooling and / or heating system of the passenger cabin, those relating to the cooling and / or heating of the high-voltage battery and the electric motor, those relating to the lighting devices (internal and external), those relating to infotainment, those relating to secondary electric drives, and in general all non-propulsive electrical loads, i.e., other than the traction motor M. The auxiliary loads are powered by the high-voltage battery B, and by the motor M only during regenerative braking. Having indicated with Pi_oad the power dissipated by all non-propulsive electrical loads (e.g., DC / DC converter, EAC air compressor, ECH coolant heating system, and the like), this can be related to the power consNoProP(t) according to the following equation (12): since the power consNoProp® actually dissipated for reasons other than propulsion is the one that powers the non-propulsive loads, minus the input PRgn2Load deriving from regenerative braking.
[0047] Since the power Pi_oad and the power PRgn2Load can be measured by current and voltage sensors of the electric / electronic components of the vehicle V, also the power consNoProp can be computed starting from physical quantities measured directly on the vehicle V, without the need to use any physical model of the vehicle V to estimate the quantities of interest, nor to calibrate such a model.
[0048] The method for determining the energy consumption of the electric vehicle V, therefore, involves measuring the physical quantities of interest (i.e.: mass, acceleration, speed, battery voltage and current, motor voltage and current, voltages and currents of non-propulsive loads) by means of the appropriate sensors discussed above, and computing the powers consprOp and consNoProp using equations (10) and (12), respectively. The total dissipated power is given by the sum of the two. Once the powers consprOp and consNoProp have been computed, it is possible to determine the instantaneous energy consumption K using equation (1 ), and from this possibly determine the residual range R by multiplying the consumption K by the total energy stored by the vehicle, i.e. , the sum of the residual energy stored in the battery B (which is known from the state of charge of the battery - SOC), the kinetic energy EKin (which can be computed as a function of the mass and current speed of the vehicle) and the potential energy Epot (which can be computed as a function of the mass and vertical displacement of the vehicle, the latter being determinable, for example, by integrating the data received from a vehicle inclination sensor).
[0049] The possibility of computing the powers conspmp(t) and consNoProp® separately using equations (10) and (12) also allows, in some preferred embodiments, to apply further processing to these quantities, even separately from each other. For example, filter functions can be applied to the power conspmpft) and / or to the power consNoProp(t), with the possibility of applying two different filter functions, which take into account the different nature of these two inputs. For example, the energy consumption / (’ can be computed using the following equation (13): where the functions fpmp(x, s) and fi\ioProP(x, t) indicate two filters. The first filter fproP(x, s) processes the variable x as a function of the space s, which is more appropriate for the power dissipated for the vehicle propulsion. The second filter fi\ioPmp(x, t) instead processes the variable x as a function of time t, which is more appropriate for the power dissipated for the non- propulsive aspects of the vehicle (which, as previously mentioned, are independent of whether the vehicle is moving or not).
[0050] By applying these filter functions, the energy consumption K’ is even more stable and less subject to fluctuations than the instantaneous energy consumption K, and the indication of residual range provided to the driver of the vehicle is even more stable.
[0051] Using the method described here, therefore, it is possible to precisely measure the loss of energy from the high-voltage battery and from the vehicle itself (i.e. , the loss of kinetic and / or potential energy). This allows to effectively mitigate the fluctuations of the consumption value (and therefore of residual range) that occur, instead, using a classic algorithm, in which the consumption is computed taking into account only the power supplied by the battery in a determined time period. In this regard, reference can be made to Figure 2, which illustrates the trend over time of some signals and physical quantities during a determined time period of use of an electric vehicle, in particular: a signal GP indicative of the use of the accelerator (solid line), a signal HB indicative of the use of the braking system (dashed line), the speed v of the vehicle (solid line), the power PBat delivered (if positive) or received (if negative) by the high-voltage battery B (solid line), and the sum constot of the powers consprOp and consNoProp (dashed line).
[0052] As discussed above, a classical algorithm is imprecise and affected by significant fluctuations because it is essentially based only on the observation of the quantity PBat (which varies sharply, as can be seen in Figure 2). As a result, a classical algorithm during accelerations is not able to distinguish whether the energy drawn from the battery is dissipated or converted into kinetic or potential energy, during decelerations it is not able to determine whether and how the braking system dissipates energy, and in general it is not able to determine the energy transfers between the vehicle components. On the contrary, the method illustrated here mitigates the fluctuations because it takes into account the conversion of energy from one form to another and the related energy transfers within the vehicle V.
[0053] For example, referring to Figure 2:
[0054] - between to and t1 the accelerator pedal GP is kept partially pressed at a constant level, the vehicle travels at a constant speed v, the total dissipated power constat is constant and essentially corresponds to the power delivered by the battery PBat,
[0055] - between t1 and t2 the driver presses the accelerator pedal fully (“tip-in”), the vehicle speed v increases, the power PBat supplied by the battery increases considerably, but the total dissipated power constot increases to a lesser extent, since a good part of the power PBat is transformed into kinetic energy that is not wasted, and only a minor part of the power PBat is dissipated more than in the previous interval, for example to counteract greater aerodynamic resistance due to the greater speed of the vehicle;
[0056] - between t2 and t3 the driver releases the accelerator pedal, the vehicle speed v decreases due to friction and aerodynamic resistance, the power PBat becomes negative since the electric motor is in regeneration, and the total dissipated power constot tends to decrease;
[0057] - between t3 and t4 the driver presses the brake pedal HB and activates the mechanical / hydraulic braking, the vehicle speed v decreases more sharply, the power PBat is zeroed as we are in a completely dissipative braking, and the total dissipated power constot increases sharply as what in the previous interval (between t2 and t3) was reconverted from kinetic energy to chemical energy is now completely dissipated by the mechanical brakes;
[0058] - between t4 and t5 the driver releases the brake pedal and we return to a “coasting” situation similar to that of the interval between t2 and t3; and
[0059] - after t5 the driver presses the accelerator pedal GP again to stabilize the vehicle speed v at the current value, and we return to a condition similar to that of the interval between to and t1 .
[0060] In general, it can be observed that during a braking, the kinetic energy of the vehicle can be transformed into chemical energy and stored in the high-voltage battery using the electric motor as a generator, as an extension of what already happens during the “coast down”. If braking is performed only by the hydraulic brake, the kinetic energy is completely dissipated. If braking is performed only by the motor M in generator mode, the kinetic energy is transformed into electrical energy and used to power the auxiliary loads L (power PRgn2Load) and, if the generated power PRgn exceeds the power demand of the loads L, the remaining part is used to recharge the battery B (power PRgn2Bat). During driving, the battery B can only be recharged by regeneration by the motor M; therefore, the power resulting from regeneration that is transferred to the battery is equal to PRgn2Bat. During the regeneration, if the battery is recharged (i.e. if PRgn2Bat > 0), then the power required by the non-propulsive loads is completely provided by the electric motor in generator mode, and there is no transfer of energy from the battery B to the loads L (i.e., PBat2Load = 0). Instead, still during the regeneration, if the battery is not recharged (i.e. if PRgn2Bat = 0), then the power required by the non-propulsive loads is greater than that provided by the electric motor in generator mode PRgn2Load, and battery B supplies the loads L with the necessary residual power (i.e., PBat2Load>0).
[0061] Of course, notwithstanding the principle of the invention, the construction details and the embodiments may vary widely with respect to what is described and illustrated purely by way of example, without thereby departing from the scope of the present invention, as defined in the attached claims.
Claims
CLAIMS1. A method of determining the energy consumption (K) of an electric vehicle (V) comprising a high-voltage traction battery (B), an electric motor (M) and one or more auxiliary electric loads (L), the method comprising: i) sensing the longitudinal speed (y(t)) of the vehicle, the longitudinal acceleration (a(t)) of the vehicle, the mass (m) of the vehicle, the power delivered (Pirc) by the electric motor (M) of the vehicle for the propulsion of the vehicle, the power regenerated (Ppgn2Bat) by the electric motor (M) of the vehicle and transferred to the traction battery (B) of the vehicle, the total power (Ptoad) consumed for supplying the auxiliary electric loads (L), and the power regenerated (Ppgn2Load) by the electric motor (M) of the vehicle and transferred to the auxiliary electric loads (L) of the vehicle; ii) determining a first value of net power (conspmp) dissipated for the propulsion of the vehicle at a determined time, by subtracting the power regenerated (Ppgn2Bat) by the electric motor (M) of the vehicle and transferred to the traction battery (B) of the vehicle and the product of mass, longitudinal speed and longitudinal acceleration of the vehicle (V) from said power delivered (Prrc) by the electric motor (M) of the vehicle for the propulsion of the vehicle; iii) determining a second value of net power (consNoProp) consumed for supplying the auxiliary electrical loads (L) of the vehicle at said determined time, by subtracting the power regenerated (Ppgn2Load) by the electric motor (M) of the vehicle and transferred to the auxiliary electrical loads (L) of the vehicle from said total power (Ptoad) consumed for supplying the auxiliary electrical loads (L); and iv) determining the energy consumption (K) of the vehicle (V) by computing the ratio between said longitudinal speed (y(t)) of the vehicle (V) and the sum of said first value of net power (consprOp) and said second value of net power (consNoProp).
2. The method of claim 1 , comprising:- before step (iv), applying a first filtering processing to said first value of net power (conspmp), wherein said first filtering processing takes into account the trend of the first value of net power (conspmp) as a functionof the distance travelled by the vehicle (V), thereby determining a first filtered value of net power (consprop)',- before step (iv), applying a second filtering processing to said second value of net power (consNoProp), wherein said second filtering processing takes into account the trend of the second value of net power (consNoProp) as a function of time, thereby determining a second filtered value of net power (consNoProp)', and- determining the energy consumption (K) of the vehicle (V) by computing the ratio between said longitudinal speed (v(t)) of the vehicle and the sum of said first filtered value of net power (consprop) and said second filtered value of net power (consNoProp).
3. The method of any of the previous claims, comprising:- sensing the amount of energy (EBat) stored in the traction battery (B);- determining the amount of kinetic energy (EKin) stored by the vehicle as a function of the longitudinal speed (v(t)) of the vehicle and the mass (m) of the vehicle;- determining the amount of potential energy (Epot) stored by the vehicle as a function of the mass (m) of the vehicle and the vertical displacement of the vehicle; and- determining the residual range (R) of the vehicle (V) by multiplying said energy consumption (K) of the vehicle (V) by the sum of said energy (EBat) stored in the traction battery (B), said kinetic energy (Enn) and said potential energy (Epot).
4. The method of any of the previous claims, wherein:- the longitudinal speed (v(t)) of the vehicle (V) is sensed by at least one speed sensor provided in the vehicle (V);- the longitudinal acceleration (a(t)) of the vehicle (V) is sensed by at least one longitudinal accelerometer provided in the vehicle (V), and / or it is determined as a function of said sensed longitudinal speed (v(t)); and- the mass (m) of the vehicle (V) is sensed by at least one vertical accelerometer provided on an element of the vehicle (V) subject to vertical displacement dynamics, and / or it is determined as a function of said longitudinal acceleration (a(t)) of the vehicle (V), and / or is provided as an input parameter of the method.
5. The method of any of the previous claims, wherein:- the power delivered (Prrc) by the electric motor (M) of the vehicle for the propulsion of the vehicle is determined by sensing the current and voltage sunk by the electric motor (M) during traction of the vehicle (V) by means of respective current and voltage sensors;- the power regenerated (PRgn2Bat) by the electric motor (M) of the vehicle and transferred to the traction battery (B) of the vehicle is determined by sensing the current and voltage provided by the electric motor (M) to the traction battery (B) during regenerative braking of the vehicle (V) by means of respective current and voltage sensors;- the total power (Ptoad) consumed for supplying the auxiliary electrical loads (L) is determined by sensing the currents and voltages sunk by the auxiliary electrical loads (L) by means of respective current and voltage sensors; and- the power regenerated (PRgn2Load) by the electric motor (M) of the vehicle and transferred to the auxiliary electric loads (L) of the vehicle is determined by sensing the current and voltage provided by the electric motor (M) to the auxiliary electric loads (L) during regenerative braking of the vehicle (V) by means of respective current and voltage sensors.
6. A system for determining the energy consumption of an electric vehicle (V) comprising a high-voltage traction battery (B), an electric motor (M) and one or more auxiliary electric loads (L), the system comprising:- at least one speed sensor configured to sense the longitudinal speed (y(t)) of the vehicle (V);- a plurality of current and voltage sensors configured to sense the current and voltage sunk by the electric motor (M) during traction of the vehicle (V), the current and voltage provided by the electric motor (M) to the traction battery (B) during regenerative braking of the vehicle (V), the currents and voltages sunk by the auxiliary electrical loads (L), and the current and voltage provided by the electric motor (M) to the auxiliary electrical loads (L) during regenerative braking of the vehicle (V);- an electronic processing unit configured to receive data from said at least one speed sensor and from said plurality of current and voltage sensors, and further configured to carry out the method of any of theprevious claims.
7. The system of claim 6, wherein:- said system comprises at least one longitudinal accelerometer configured to sense the longitudinal acceleration (a(t)) of the vehicle (V), and / or- said electronic processing unit is further configured to determine the longitudinal acceleration (a(t)) of the vehicle (V) as a function of the sensed longitudinal speed (y(t)) of the vehicle (V).
8. The system of claim 6 or claim 7, wherein:- said system comprises at least one vertical accelerometer configured to be mounted on an element of the vehicle (V) subject to vertical displacement dynamics and configured to sense the mass (m) of the vehicle (V), and / or- said electronic processing unit is further configured to determine the mass (m) of the vehicle (V) as a function of the longitudinal acceleration (a(t)) of the vehicle (V), and / or- said electronic processing unit is further configured to receive the value of the mass (m) of the vehicle (V) as a parameter from a memory.
9. An electric vehicle (V) comprising a high-voltage traction battery (B), at least one electric motor (M), and one or more auxiliary electric loads (L), wherein:- the traction battery (B) is configured to provide power (PBat2Load) to said auxiliary electric loads (L) and to provide power (PBat2Trc) to said electric motor (M) during traction of the electric vehicle (V); and- during regenerative braking, said electric motor (M) is configured to provide power (PRgn2Bat) to said traction battery (B) and / or provide power (PRgn2Load) to said auxiliary electric loads (L); and wherein the vehicle further comprises a system according to any of claims 6 to 8.
10. A computer program product loadable in the memory of an electronic processing unit and comprising instructions that, when the program is executed by the electronic processing unit, cause the electronic processing unit to carry out the method of any of claims 1 to 5.
Citation Information
Patent Citations
Systems and methods of battery management and control for a vehicle
US20230347779A1