A method for controlling the electrical power delivery from a battery to one or more electric motors of an electric powertrain of a vehicle

Abstract

There is described a method for controlling the electrical power delivery from a battery to one or more electric motors of an electric powertrain of a vehicle, the method comprising: -detecting the occurrence of a deceleration manoeuvre (BRK) of the vehicle, in particular a braking manoeuvre, -detecting the occurrence of an acceleration manoeuvre (PRF) of the vehicle, subsequent to said deceleration manoeuvre (BRK), -enabling, during a first time interval (tPRF), a first ceiling (PPRF) of electrical power delivery (PW) upon detecting the occurrence of said acceleration manoeuvre (PRF) of the vehicle, enabling, during the first time interval, a request command for maintaining the first ceiling (PPRF) of electric power delivery (PW) for an extended time interval (t_PRF _ XT) with an end (tXT) following an end (t2) of said first time interval (tPRF), -maintaining the first ceiling ( PREF) of electric power delivery (PW) until the end (tXT) of said extended time interval (t_PRF_XT) if said command (CMD) is given (tcMD) during said first time interval (tPRF), - enabling a second ceiling (PIDL) of electric power delivery (PW), lower than said first ceiling (PPRF), at the end (t2) of said first time interval (tPRF) and for a second time interval (tIDL) if said command is not given during said first time interval (tPRF).

Description

[0001] "A method for controlling the electrical power delivery from a battery to one or more electric motors of an electric powertrain of a vehicle"

[0002] ★★★★

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The present invention refers to the control of the electrical power delivery in electric powertrains for vehicles, specifically for BEV vehicles. More specifically, the present invention has been developed with reference to the electrical power management in driving styles typically adopted in sports competitions.

[0006] Known Art

[0007] For the vehicles with an electric powertrain (BEVs), the maximum performance of the powertrain is strongly limited by the thermal constraints of the high- voltage battery and of the electric motors. The factor between the two (battery and electric motor(s)) which may be more limiting generally depends on the architecture of the high voltage electric plant, but in high-performance vehicles it is generally observed that the more limiting factor is the battery.

[0008] In given driving conditions, e.g. a timed lap on a very long track or an endurance competition, the thermal constraints of the battery - even employing the maximum cooling power - may not enable completing the lap (and, on a larger scale, the competition) without power limitations, in order to prevent an overheating of the components. This downgrading of the power delivery has a significant impact on the lap times. If precautions are not adopted, the limitations of the power delivery due to downgrading appear before the end of the timed lap, and are applied until a sharp deceleration or a complete stop of the vehicle take place, both being conditions incompatible with the goal of the timed lap or the endurance competition.

[0009] Typically, an overheating of the high-voltage battery and of the electric motors is controlled by using regulation maps as a function of the temperature, which limit, with a large safety margin, the maximum power which may be delivered by the battery of the electric motors, i.e. the maximum mechanical power available to the wheels. This approach is useful for a daily use of a vehicle, but it is probably the worst approach in a timed lap or in a competition (whether endurance or not). For competitions, strategies are known for controlling the power within a single lap, but such strategies are based on the use of a GPS on board the vehicle and of a transponder at the finish line, in such a way as to know at each instant the exact position of the vehicle along the track. This is clearly unfeasible for vehicles approved for normal road use, irrespective of their occasional use (with the enablement of corresponding driving modes) for competitive events, including endurance events. Moreover, it is necessary to bear in mind that for a vehicle approved for road use it is anyway of paramount importance to make the interventions as little perceivable by the driver as possible.

[0010] Object of the Invention

[0011] The invention aims at solving the technical problems mentioned in the foregoing. Specifically, the object of the invention is to provide a method for controlling the electrical power delivery in an electric powertrain of a vehicle which simultaneously enables both limiting the power, in order to safeguard the power train, and to have a zero or negligible impact on the vehicle performances, particularly during competitions.

[0012] Summary of the Invention

[0013] The object of the invention is achieved by means of a method having the features set forth in the claims that follow, which form an integral part of the technical disclosure provided herein in relation to the invention.

[0014] Brief Description of the Figures

[0015] The invention will now be described with reference to the annexed Figures, which are provided by way of non-limiting example only and wherein:

[0016] - Figure 1 shows a flow diagram representative of a method according to the invention,

[0017] - Figure 2 shows a time graph representative of an evolution of the power delivery along a road section, specifically a straight section of a circuit, after a braking step, according to the method of the invention,

[0018] - Figure 3 shows a graph similar to Figure 2, but referring to a condition of further power request by the driver, according to the method of the invention.

[0019] Detailed Description

[0020] Referring to Figure 1, it represents a graph showing a method for controlling the electrical power delivery from a battery to one or more electric motors of an electric powertrain of a vehicle according to the invention. The reference 1 generally denotes the graph and, implicitly, the method according to the invention.

[0021] In various embodiments of the invention, with further reference to Figures 2 and 3, the method schematically shown in Figure 1 comprises: detecting the occurrence of a deceleration manoeuvre BRK of the vehicle, in particular a braking manoeuvre, detecting the occurrence of an acceleration manoeuvre PRF of the vehicle subsequent to said deceleration manoeuvre BRK,

[0022] - enabling, during a first time interval tpRF, a first ceiling PPRF of electrical power delivery PW upon detecting the occurrence of the acceleration manoeuvre PRF of the vehicle, - enabling, during the first time interval tpRF, an availability of a request command CMD for maintaining the first ceiling PPRF of electrical power delivery PW for an extended time interval t_pRF_xT with an end txT following an end tp of the first time interval tpRF,

[0023] - maintaining the first ceiling PREF of electric power delivery PW until the end txT of the extended time interval t_pRF_xT if the command CMD is given during the first time interval tpRF,

[0024] - enabling a second ceiling PIDL of electrical power delivery PW, lower than the first ceiling PPRF, at the end tp of the first time interval tpRF and for a second time interval tiDL, if the command CMD is not given during the first time interval tpRF.

[0025] Figures 2 and 3, each corresponding to a time diagram of the electrical power delivered by the battery to one or more electric motors of the powertrain, represent the evolution in time shown by the states of the graph in Figure 1, and will now be described in detail.

[0026] The sequence of events on which the graph of Figure 1 is based and which is shown in Figures 2 and 3 takes place between two deceleration manoeuvres BRK, in particular braking manoeuvres BRK, and therefore may correspond to the travel along a section of road or circuit which starts when leaving a first curve, develops along a straight section or generally a section, between two subsequent curves, which is travelled along without significant braking events, and ends with the braking which precedes a second curve.

[0027] The operating assumption at the basis of the invention is simple: if, for any reason, it is necessary to limit the power employed during a timed lap, and thus it is necessary to limit the power investment during the lap, it is better to invest power at the end of a curve than along a straight section. This, however, does not apply to specific needs, such as: circuits or routes wherein the performance improves if, also along the straight section, a power is invested having a ceiling corresponding to the ceiling envisaged for the end of the curve; the overtaking of another vehicle along the straight section.

[0028] That being said, and with reference to the Figures 2 and 3, certain time intervals are defined which are associated with the following references:

[0029] - the time instants to and ti - the instant ti following the instant to - define a time interval tBRK during which the deceleration manoeuvre BRK detected at block 2 takes place. Preferably, detecting the occurrence of the deceleration manoeuvre as per block 2 comprises, alternatively, either detecting an actuation of an accelerator pedal GP which is less than a first actuation threshold THRRLS, or detecting an actuation of a brake pedal BP which is greater than a second actuation threshold THRBR. Both thresholds are marked in Figure 2 and in Figure 3;

[0030] - the time instants ti and t2 - the instant t2 following the instant ti - define the time interval tpRF described in the foregoing, during which the ceiling PREF of electrical power PW applies. The instant ti substantially marks the boundary between the deceleration manoeuvre BRK and the acceleration manoeuvre PRF detected at block 4. Preferably, detecting the occurrence of the acceleration manoeuvre PRF of the vehicle comprises detecting an actuation of the accelerator pedal GP greater than a third actuation threshold THRGP, wherein the third actuation threshold THRGP is greater than the first actuation threshold THRRLS; the time instants t2 and ts the instant ts following the instant t2 - define the time interval tiDL during which the second ceiling PIDL of electrical power PW applies, which ceiling is lower than the ceiling PPRF;

[0031] - the time instants ts and t4 - the instant t4 following the instant ts - define a new time interval tsRK associated with a new deceleration manoeuvre BRK, which is detected in the same manner as per block 2;

[0032] - the time instants txT and ti - the instant txT following the instant ti and following the instant t2, which marks the end of the interval tpRF - define the extended time interval tpRF_xT. It will be observed, therefore, that the interval tpRF_xT has a longer duration than the time interval tpRF. In preferred embodiments, the time instant txT coincides with the instant ts, and therefore the time interval tpRF_xT has a duration which equals the sum of the durations of the intervals tpRF and tiDL• This means that enabling the power delivery of the electric power train at the first power level PPRF beyond the end t2 of the first time interval tpRF comprises maintaining the first ceiling PPRF of electrical power PW until the detection of a new deceleration manoeuvre BRK.

[0033] Generally speaking, however, the duration of the extended time interval tpRF_xT may be shorter, with an end preceding the end ts (albeit remaining greater than the duration of the interval tpRF), if, for example, the temperature conditions of the battery do not allow enabling the ceiling PPRF for a duration which equals the sum of the durations of the intervals tpRF and tiDL. In other words, in some conditions it may not be possible to maintain the enablement of the delivery of the power PPRF until the detection of a new braking manoeuvre. Moreover, the duration of the interval tpRF_xT may be shorter than the sum of the durations of the intervals tpRF and tiDL and may be equal to a predetermined value, which if needed may be retrieved from a map as a function of the operating conditions of the powertrain.

[0034] There will now be described a manoeuvre which covers the time interval of the graphs of Figures 2 and 3, both in the case that the command CMD is not given (Figure 2) and in the case that the command CMD is given (Figure 3).

[0035] At the instant to the vehicle approaches a curve, with a consequent deceleration manoeuvre BRK (detected at block 2), which corresponds to a release of the accelerator pedal GP (GP < THRRLS) and / or to a pressure of the brake pedal BP (BP > THRBP). The references GP and BP are associated with the respective curves of the evolution in time in Figure 2 and in Figure 3. At the instant ti the vehicle starts the manoeuvre for leaving the curve, with an actuation of the accelerator pedal GP (GP > THRGP), which causes the detection of the acceleration manoeuvre PRF at block 4. The ceiling of the power PW (see the curve in solid lines on the diagram of Figure 2) transitions from a minimum level PBRK which may be delivered in the deceleration step to the level PPRF. This, however, is not a strictly necessary condition, since the ceiling of the deliverable power PW may be set to the level PPRF also during the manoeuvre BRK (which presumably will not involve any power request).

[0036] At instant ti a timer starts which stops when reaching the instant tp, which corresponds to an instant of depletion of the availability window of the command CMD. The timer is used for recording a possible event of giving a command CMD, and in particular to determine whether the command CMD is given at an instant tcMD within the interval tpRF, or whether the instant is a general time instant t away from the instant ti of an interval greater than tpRF, in other words whether the instant tp has been exceeded, beyond which the command CMD is no longer available.

[0037] In the case of Figure 2, no command CMD is given during the first interval tpRF. As a consequence, referring to the graph of Figure 1, from a node N_PRF of the graph, a transition takes place to the block 8, during which the ceiling of electrical power PW available for the delivery is reduced to the second level PIDL.

[0038] The evolution in time of the delivered electrical power PW is visible on the respective solid-line curve, which has the same reference PW in Figure 2, whereas the dashed line associated with the reference PWMAX indicates the course in time of the ceiling enabled for the power PW.

[0039] As can be seen in Figure 2, the ceiling goes back to the first level PPRF as soon as the new deceleration manoeuvre BRK is detected at the instant ts (transition to the node N_BRK and return to block 2).

[0040] As stated in the foregoing, this is not strictly necessary, but it represents a preferred option since it results in better performances, as it implies that the first level of power PPRF is already available as soon as the new deceleration manoeuvre stops, without having to wait for the end thereof for a new enablement.

[0041] The command CMD may be given by means of a control element which may be actuated by the vehicle driver, specifically a paddle control SP+ installed at a steering wheel of the vehicle.

[0042] By way of example, the paddle control SP+ is normally used to regulate the level of the vehicle motor brake, and thus to select the levels of resistance torque of the electric powertrain of the vehicle during a deceleration, which is a function associated with the reference A in the Figures 2, 3, whereas during the interval tpRF it becomes associated with the function of giving the command CMD, reference B in the Figures 2, 3. It will be observed that, if the command CMD is not given before the instant t2, the paddle control SP+ is again associated with the function of selecting the levels of resistance torque of the electric powertrain of the vehicle (reference A).

[0043] In the case of Figure 3, the command CMD is given at the instant tcMD within the first interval tpRF. As a consequence, referring to the graph of Figure 1, a transition takes place from the graph node N_PRF to a node N_XT_IN and to block 6, so that the ceiling of electrical power PW available for delivery is maintained at the level PPRF throughout the interval tpRF_xi.

[0044] The evolution in time of the delivered electrical power PW is visible on the respective solid-line curve, which has the same reference PW as in Figure 3, whereas the curve in dashed lines associated with the reference PWMAX indicates the course in time of the ceiling enabled for the power PW.

[0045] The reference PIDL in brackets is only used to underline the different values of the power ceilings PPRF and PIDL (PPRF being still active), whereas, as in Figure 2, the dashed line PWMAX indicates the course in time of the ceiling enabled for the power PW.

[0046] The command CMD is given by means of the paddle control SP+, which however is again exclusively associated with the function of regulating the motor brake level as soon as the command CMD is given. Substantially, the control element SP+ is associated with a first function of giving the command CMD until the event, among the following events, which occurs first:

[0047] - the giving of the command CMD,

[0048] - the end tp of the first time interval tpRF, and wherein the control element is associated with a second function (for example regulating the level of the motor brake) which is different from the first function, after the event which takes place first.

[0049] In the conditions of Figure 3, the vehicle may therefore be provided with a constant ceiling of deliverable power, which is equal to the first level PPRF from leaving the curve to the end of the straight section, thereby enabling both a further reduction of the lap time during a timed lap, and the complete execution of a possible overtaking. In a preferred embodiment, the first level PPRF has the value which is lowest among the following: the maximum electrical power which may be allocated to the vehicle propulsion (such value may possibly depend on the selected driving mode), and

[0050] - a difference between a short-term power limit (which generally corresponds to a time interval of 3 seconds) which may be delivered by the battery, and a power absorbed by the user devices on board the vehicle which have higher priority.

[0051] This means that the value of the ceiling PPRF, as well as the value of the ceiling PIDL, may vary in time as a function of the evolution of the performance profiles of the battery.

[0052] As can be seen in Figure 3, when the command CMD is given, the ceiling PWMAX of the power PW is maintained at the first level PPRF throughout the time interval from to to t4, but it might anyway be reduced to PIDL during the manoeuvre BRK, albeit this is not a preferred solution.

[0053] The person skilled in the art will appreciate that, thanks to the method according to the invention, the vehicle driver will have availability of a higher power for a longer time than normally envisaged in the state of the art, without jeopardizing the integrity and the functionality of the powertrain. In this regard, particular importance is given to the choice of the instant t2 as the threshold for giving the command CMD: the instant t2 is an instant in time which is advanced enough to enable giving the command in the widest possible time window for the envisaged practical purposes, but which is far enough from instant ts to prevent the request for maintaining the ceiling at the first level PPRF from occurring in a moment when the vehicle has already travelled a substantial part of the straight section, with a thermal evolution of the batteries which makes further thermal overloads unfeasible.

[0054] Of course, the implementation details and the embodiments may amply vary with respect to what has been described and illustrated herein, without departing from the extent of the present invention as defined in the annexed claims.

Claims

CLAIMS1. A method for controlling the electrical power delivery from a battery to one or more electric motors of an electric powertrain of a vehicle, the method comprising : detecting the occurrence of a deceleration manoeuvre (BRK) of the vehicle, in particular a braking manoeuvre, detecting the occurrence of an acceleration manoeuvre (PRF) of the vehicle subsequent to said deceleration manoeuvre (BRK),- enabling, during a first time interval (tpRF), a first ceiling (PPRF) of electrical power delivery (PW) upon detecting the occurrence of said acceleration manoeuvre (PRF) of the vehicle, enabling, during the first time interval, a request command for maintaining the first ceiling (PPRF) of electrical power delivery (PW) for an extended time interval (tpRF_xT) with an end (tx?) following an end (tp) of said first time interval (tpRF),- maintaining the first ceiling (PREF) of electric power delivery (PW) until the end (tx?) of said extended time interval (t_pRF_xT) if said command (CMD) is given (tcMp) during said first time interval (tpRF),- enabling a second ceiling (PIDL) of electric power delivery (PW), lower than said first ceiling (PPRF), at the end (to) of said first time interval (tpRF) and for a second time interval (tiDL) if said command is not given during said first time interval (tpRF).

2. The method of claim 1, wherein said maintaining the first ceiling (PREF) of power delivery (PW) until the end (txT) of said extended time interval (tpRF_xT) comprises maintaining the enablement of the first ceiling (PREF) of power delivery (PW) until the detection of a new deceleration manoeuvre (BRK).

3. The method of claim 2, wherein the end (tx?) of said extended time interval (tpRF_xT) coincides with the end (ts) of the second time interval (tier).

4. The method of claim 1, wherein said extended time interval (tpRF_xT) has a predetermined duration with and end (tx?) preceding the end (ts) of said second time interval (tior).

5. The method of any one of the preceding claims, wherein said enabling said second ceiling (PIDL) of electrical power delivery (PW) comprises disabling said first ceiling (PPRF).

6. The method of any one of the preceding claims, comprising disabling an availability of said command (CMD) after said command (CMD) has been given.

7. The method of any one of the preceding claims, comprising disabling an availability of said command (CMD) if said command (CMD) is not given by the end (to) of the first time interval (tpRF).

8. The method of any one of the preceding claims, wherein said command (CMD) is given by means of a control element operable by a driver of the vehicle, particularly a paddle control (SP+) installed at a steering wheel of the vehicle.

9. The method of claim 8, wherein said control element (SP+) is associated with a first function of giving said command (CMD) until the event, chosen from the following events, which occurs first:- the giving of said command (CMD),- the end (tp) of said first time interval (tpRF), and wherein a second function, different from the first function, is associated with said control element (SP+) after the event occurring first.

10. The method of any one of the preceding claims, wherein said detecting the occurrence of a deceleration manoeuvre (BRK) of the vehicle comprises, alternativelyor in combination:- detecting an actuation of an accelerator pedal (GP) of less than a first actuation threshold (THRRLS),- detecting an actuation of a brake pedal (BP) greater than a second actuation threshold (THRBP), and wherein said detecting the occurrence of a vehicle acceleration manoeuvre (PRF) includes detecting an actuation of an accelerator pedal (GP) greater than a third actuation threshold (THRGP), wherein the third actuation threshold (THRGP) is greater than the first actuation threshold (THRRLS).

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