A method for controlling torque of one or more electric motors of an electric powertrain of a vehicle in a closed loop

Abstract

A method for controlling torque of one or more electric motors (M1; M2; M3; M4) of an electric powertrain of a vehicle (V) in a closed loop is described. The method determines a correction to be applied to a torque value determined in an open loop, wherein the correction is distributed in accordance with a target torque distribution ratio.

Description

Technical Field

[0001] The present invention relates to a vehicle having an electric powertrain of the type comprising one or more traction motors distributed between the front axle and the rear axle. Background Technology

[0002] In vehicles with electric powertrains, it is crucial to control the power delivery from one or more batteries to one or more electric motors (and vice versa in regeneration mode) in order to respect the constraints of torque delivery and distribution envisioned for vehicle dynamics objectives, and to avoid load curves that could damage the motors and / or batteries (for both motors and batteries).

[0003] However, in the prior art, the delivery of electrical power to the motor and, in regenerative mode, the supply of power to the battery are controlled solely based on torque targets conceived by vehicle dynamics. In other words, the operating conditions are acceptable, albeit temporary, but exceed a critical power delivery or supply threshold. Furthermore, exceeding this threshold often occurs without the powertrain control strategy being aware of it, precisely because the latter is based solely on the torque target of each motor, and therefore any implementation of any type of corrective action for control (and regulation) and electrical power flow is essentially ineffective.

[0004] As part of the solution to the technical problem under discussion, a purely model-based method for controlling the torque of an electric motor can be implemented, where the control operates in an open-loop manner. An example of this method has been proposed by the applicant in Italian Industrial Invention Patent Application No. 102023000023517. While effective under a wide range of operating conditions, these methods are inherently unable to account for sudden, further influencing factors that are not conceived (or cannot be conceived) by the open-loop computational model, and therefore, it is impossible to implement corrections based on these further factors.

[0005] Purpose of the invention

[0006] The present invention aims to solve the technical problems outlined above. Specifically, the object of the present invention is to provide a method for controlling, particularly for real-time control, one or more electric motors of a vehicle's electric powertrain, while adhering to both torque distribution targets within the powertrain (which are determined based on the vehicle's dynamic requirements) and thresholds for power delivery or absorption, and also taking into account further influencing factors that suddenly arise and are not considered (and cannot be considered) by the open-loop calculation model, wherein it is therefore impossible to implement corrections based on said further factors. Summary of the Invention

[0007] The object of the present invention is achieved by means of a method having the features set forth in the following claims, which form part of the technical disclosure provided herein in relation to the present invention. Attached Figure Description

[0008] The invention will now be described with reference to the accompanying drawings, which are provided by way of non-limiting example only, and in which:

[0009] - Figure 1 This is a block diagram illustrating the method according to the present invention.

[0010] - Figure 1A A general diagram of a vehicle in which the method according to the invention can be implemented is shown, while Figure 1B A preferred embodiment is shown;

[0011] - Figure 2 The first derivation sequence of the method according to the invention is shown, and Figure 3 and Figure 4 The actual implementation is shown.

[0012] - Figure 5 A second derivation sequence according to the method of the present invention is shown, and Figure 6 and Figure 7 The actual implementation method is shown. Detailed Implementation

[0013] In various embodiments, references Figure 1 and Figure 1A The present invention includes a method for controlling the torque of one or more electric motors M1, M2, M3, and M4 of an electric powertrain for a vehicle V. The method is described with reference to a very general configuration of the powertrain, including a first electric motor M1 associated with the left wheel RL of the rear axle RA, a second electric motor M2 associated with the right wheel RR of the rear axle RA, a third electric motor M3 associated with the left wheel FL of the front axle FA, and a fourth electric motor M4 associated with the right wheel FR of the front axle FA. However, it is generally applicable to a variety of configurations with a smaller number of motors and their different arrangements and associations, such as, for example, a preferred configuration (…). Figure 1B It has motors M1 and M2 associated with wheels RL and RR respectively, and a third motor M3 associated with the two wheels FL and FR of the front axle FA.

[0014] According to the present invention, and with reference to Figure 1 The method is schematically illustrated by means of a block diagram with general reference numeral 1, and includes:

[0015] - Define a first reference limit value (Plim) for the nth power current absorbed by each of the nth motors M1, M2, M3, M4 (n=1, 2, 3, 4). ,n,prop Furthermore, for each of the nth motors M1, M2, M3, and M4, a second reference limit value P is defined for the nth power flow generated by the nth motor. lim,n,reg ,

[0016] - Define the first total reference limit value P for the absorbed power flow. lim,TOT_PROP , including the power flow P delivered in each nth limit lim,n,prop The sum of these, and define the second total reference limit value P of the resulting electric power flow. lim,TOT_REG This includes the power flow P generated by each nth limit. lim,n,reg The sum,

[0017] - The torque T delivered by each nth motor n The first extreme reference value Tn,PROP_OL is defined (block OL) as the first total limit value P of the absorbed power flow. lim,TOT_PROP And the torque T, which is one or more of the electric motors n The function defines the boundary conditions (block m, TV) and the torque T absorbed by each nth motor. n Second extreme reference value T n,REG_OL The second total limit value P is defined as the generated electrical power flow. lim,TOT_REG And the torque T, which is one or more of the electric motors n The function defines the boundary conditions (block m, TV).

[0018] - Determine (block CL) the torque T to be applied by each nth motor. n One or more first reference extreme values ​​T n,PROP_OL First torque correction T PROP_CL And calculate the torque T to be applied to each nth motor. n One or more second extreme reference values ​​T n,REG_OL Second torque correction T REG_CL ,

[0019] –Based on the target torque segmentation ratio m, the first torque correction T CL,PROP Segmentation (block m) CL The first correction fraction (T) associated with the front axle FA of the vehicle. 3,PROP_CL ;T 4,PROP_CLIt is also divided into a second correction portion T associated with the rear axle RA of the vehicle. 1,PROP_CL ;T 2,PROP_CL And according to the target torque division ratio m, the second torque correction T CL,REG The third correction section T is divided into sections associated with the front axle FA of the vehicle. 3,REG_CL ;T 4,REG_CL It is also divided into a fourth correction section T associated with the rear axle RA of the vehicle. 1,REG_CL ;T 2,REG_CL ,

[0020] -The first correction part T 3,PROP_CL ;T 4,PROP_CL A set of first extreme reference values ​​for the torque delivered to the front axle by one or more corresponding electric motors.

[0021] -The second correction part T 1,PROP_CL ;T 2,PROP_CL A set of first extreme reference values ​​for the torque delivered to the rear axle by one or more corresponding electric motors.

[0022] -The third correction part T 3,REG_CL ;T 4,REG_CL The set of second extreme reference values ​​applied to the torque absorbed from the front axle by one or more corresponding electric motors, and

[0023] -The fourth correction part T 1,REG_CL ;T 2,REG_CL A set of second extreme reference values ​​applied to the torque absorbed from the rear axle by one or more corresponding electric motors.

[0024] The methods and steps listed above will now be described in detail.

[0025] Regarding the value P lim,n,prop and P lim,n,reg The definition, in the preferred embodiment - includes Figure 1 The value shown in the figure is calculated in accordance with the manner described in the aforementioned document 102023000023517. To recall the relevant content of that document, in the presence of one or more electric motors operatively associated with the front and / or rear axles of the vehicle, or with a corresponding individual wheel on the same axle, the power flow is exchanged between each motor and (at least) the vehicle's axle or (at least) a wheel to provide traction to the latter. The phrase "power flow" refers to the power flow entering the electric motor (from the battery BT), i.e., the flow that generates driving action by the motor, where power is delivered by the motor, and the power flow exiting the electric motor (and entering the battery BT), i.e., the flow generated when the motor is subjected to a resistance load (braking or decelerating due to vehicle inertia) and absorbs power while operating as a generator.

[0026] The nth power flow P lim,n,prop and P lim,n,reg In each limit value, the indices n=1, 2, 3, 4 in the currently considered embodiment are associated with the general power flow related to the nth motor. The nth power flow P lim,n,prop and P lim,n,reg Each limit value is defined as having the expression The polynomial (and therefore the quadratic polynomial), where a n b n c n It depends on the coefficient of the speed of the corresponding nth motor, and T n This is the torque of the corresponding nth motor (which can be propulsion torque, associated with the index PROP,prop in the currently used reference numerals, or regenerative torque, REG,reg in the currently used reference numerals). In a preferred embodiment of the invention, the first total reference limit value P of the absorbed power flow is... lim,TOT_PROP_OL Including the nth limiting absorbed power flow P lim,n,PROP The sum of (in the most general instance, P) lim,TOT_PROP_OL =P lim,1,prop +P lim,2,prop +P lim,3,prop +P lim,4,prop ), with the second total reference limit value P of the generated electric power flow. lim,TOT_REG_OL Including the power flow generated by each nth limit Plim,n,reg The sum of (in the most general instance, P) lim,TOT_REG_OL =P lim,1,reg +P lim,2,reg +P lim,3,reg +P lim,4,reg In the same manner. The suffix "OL" as a subscript to the listed values ​​indicates that the reference value is determined in an open loop, i.e., based on a calculation model—as in the preferred embodiment of the invention—or the listed plan.

[0027] Once the value P lim,TOT_PROP_OL and P lim,TOT_REG_OL It is known that, according to the teachings of document 102023000023517 mentioned above (block OL), it can be used as the first total limit value P. lim,TOT_PROP_OL and the torque T as one or more in the electric motor n The function is defined by at least one boundary condition (block m, TV) to calculate the torque T delivered by each nth motor. n First extreme value reference value T n,PROP_OL And as the second total limit value P lim,TOT_REG_OL and the torque T as one or more in the electric motor nThe boundary conditions (block m, TV) are defined as a function of the function to calculate the torque T absorbed by each nth motor. n Second extreme reference value T n,REG_OL Therefore, a total value T was calculated. 1,PROP_OL T 2,PROP_OL T3,P ROP_OL T 4,PROP_OL and T 1,REG_OL T 2,REG_OL T 3,REG_OL T 4,REG_OL These values ​​are extreme values, meaning they are the (absolute) maximum values ​​in their respective operating domains (transmitted torque and absorbed torque, respectively). If these values ​​are considered as functions of their respective signs (positive for delivered torque and negative for absorbed torque), it can be observed that the value T... 1,PROP_OL T 2,PROP_OL T 3,PROP_OL T 4,PROP_OL Corresponding to the maximum torque value, and the value T 1,REG_OL T 2,REG_OL T 3,REG_OL T 4,REG_OL This corresponds to the minimum torque value.

[0028] Generally, examples of boundary conditions can include at least one of the following:

[0029] The ratio m (block m) of the torque delivered and / or absorbed by the front axle FA to the torque delivered and / or absorbed by the rear axle RA of the motor vehicle V.

[0030] The relationship between the torque delivered and / or absorbed by the right and left wheels of the axle FA or RA of a motor vehicle (block TV).

[0031] In the most general example of a vehicle V having a powertrain including electric motors for each of the wheels FL, FR, RL, RR, the value P can be expressed by the following expression. lim,n,prop :

[0032] -Motor M1:

[0033] -Motor M2:

[0034] -Motor M3:

[0035] -Motor M4:

[0036] And the value P lim,n,REG It has the following expression:

[0037] -Motor M1:

[0038] -Motor M2:

[0039] -Motor M3:

[0040] -Motor M4:

[0041] Coefficients a1, b1, c1, a2, b2, c2, a3, b3, c3, a4, b4, c4 (with index) PROP Or has an index REG The operating mode (for delivering torque) is mapped to the rotational speed of each of the motors M1, M2, M3, and M4. PROP Used to absorb torque REG The expression for the nth electric power flow varies as a function of the speed of the nth motor.

[0042] Describe the electric power flow P lim,TOT,PROP_OL or P lim,TOT,REG_OL Each equation has four variables T1, T2, T3, T4 (with indexes) PROP Or has an index REG The equations of , which can be solved if combined into a system with three further equations (corresponding to the boundary conditions mentioned above), include:

[0043] - The first difference between the second torque T2 delivered (or absorbed) by the second motor M2 to (or from) the rear right wheel RR and the first torque T1 delivered (or absorbed) by the first motor M1 to (or from) the rear left wheel RL. (2A). This difference can be used (as a criterion for calculating P). lim,TOT,PROP_OL Boundary conditions or as used to calculate P lim,TOT,REG_OL The function (with boundary conditions) has different values;

[0044] - The second difference between the fourth torque T4 delivered (or absorbed) by the fourth motor M4 to (or from) the front right wheel FR and the third torque T3 delivered (or absorbed) by the third motor M3 to (or from) the front left wheel FL. (2B). As mentioned earlier, this difference can be used as (as a tool for calculating P) lim,TOT,PROP_OL Boundary conditions or as used to calculate P lim,TOT,REG_OL The function (with boundary conditions) has different values;

[0045] In other words, these two relationships represent the situation of active asymmetric torque distribution between the wheels of the rear axle RA and the front axle FA (torque vectoring - coefficient 2 is just a convention, stemming from the fact that the quantity , This represents the torque subtracted from one wheel and transferred to the other, and therefore the global difference is... )

[0046]

[0047]

[0048] The ratio m of the sum of the fourth torque T4 and the third torque T3 delivered (or absorbed) by motors M4 and M3 to (or from) the wheels of the front axle FA to the sum of the torques T2 and T1 delivered (or absorbed) by motors M2 and M1 to (or from) the wheels of the rear axle RA, therefore

[0049]

[0050] Therefore, m represents the torque distribution ratio between the front and rear axles. As mentioned earlier, this difference can be used as (as a parameter for calculating P) lim,TOT,PROP_OL Boundary conditions or as used to calculate P lim,TOT,REG_OL The function (with boundary conditions) has different values;

[0051] Quantity P lim,TOT (with index) PROP Or has an index REG The expression for the boundary conditions describes a four-dimensional geometric trajectory (dimensions T1, T2, T3, T4), which cannot be represented graphically, but is fully defined in itself. Similarly, the expression for the boundary conditions describes the geometric trajectory in the same four-dimensional space, which is related to the geometric trajectory P. lim,TOT The common intersection of the coordinates produces a trajectory, which has coordinates (T). 1,PROP_OL T 2,PROP_OL T 3,PROP_OL T 4,PROP_OL ) or (T 1,REG_OL T 2,REG_OL T 3,REG_OL T 4,REG_OL These coordinates correspond to the maximum or minimum torque (considered in terms of their signs) that can be delivered or absorbed by motors M1, M2, M3, and M4 at a given speed and as a function of power limits conceived for instantaneous operating conditions.

[0052] In other words, the geometric locus P lim,TOT,PROP_OL and P lim,TOT,REG_OL It is an isopower trajectory (maximum and minimum power, considered while preserving the sign), and a coordinate trajectory (T). 1,PROP_OL T 2,PROP_OL T 3,PROP_OL T 4,PROP_OL ) or (T 1,REG_OL T2,REG_OL T 3,REG_OL T 4,REG_OL This should be located above it to simultaneously satisfy the conditions for torque distribution within the powertrain and the limiting conditions for the total power flow in the powertrain. Furthermore, in this way, a first overall extreme reference value for the delivered torque (also known as the first overall target or center-of-gravity torque) can be defined – which is determined in the open loop – T. TOT,PROP_OL =T 1,PROP_OL T 2,PROP_OL T 3,PROP_OL T 4,PROP_OL And the second total extreme reference value for the absorbed torque (also known as the second total target or center of gravity torque) - which is determined in the open loop, T TOT,REG_OL = T 1,REG_OL T 2,REG_OL T 3,REG_OL T 4,REG_OL .

[0053] According to the present invention, the first torque correction T CL,PROP Second torque correction T CL,REG Based on the center of gravity correction (i.e., the correction of the target value), the target torque T is thus determined in the open loop. TOT,PROP_OL T TOT,REG_OL The corrections are then applied, and these are distributed to the individual motors based on the ratio m. In this respect, an asymmetric torque distribution will be observed between the left and right sides. and No correction T involved CL,PROP and T CL,REG The determination of: This asymmetry is a value determined in the open loop (therefore determined by model-based calculations or by means of mapping; it is not altered by corrections in the open loop, nor does it appear in the expression for the center of gravity torque due to self-cancellation during summation). For and The definitions, which relate to the torque generated on the left side of the vehicle, show the opposite sign and the same absolute value as the torque generated on the right side of the vehicle. Corrections may be applied solely based on the torque distribution ratio between the front axle (FA) and the rear axle (RA).

[0054] As in Figure 1 As can be seen in the graph, torque T TOT,PROP_OL T TOT,REG_OL It's just one piece of data input into block CL. In other words, it's the correction T. PROP_CL and T REG_CL It is determined to be the following function:

[0055] -Including the torque T of each nth motor n First extreme reference value (T) 1,PROP_OL T2,PROP_OL ;T 3,PROP-OL T 4,PROP_OL The first total extreme value reference value (T) of the sum of ) TOT,PROP_OL ),

[0056] -Including the torque T of each nth motor n The second extreme reference value (T) 1,REG_OL T 2,REG_OL ;T 3,REG_OL T 4,REG_OL The second total extreme value reference value (T) of the sum of ) TOT,REG_OL ),

[0057] - The first total reference limit value of the powertrain's electric power flow (P lim,TOT_PROP The second total reference limit (P) of the powertrain's electric power flow. lim,TOT_REG ),

[0058] -Target propulsion torque (T) TGT_PROP ),

[0059] -Target regenerative torque (T) TGT_REG ),

[0060] - Total torque delivery limit T of one or more electric motors TOT,LIM_MOT_PROP (T) 1,LIM_MOT_PROP T 2,LIM_MOT_PROP T 3,LIM_MOT_PROP ;T 4,LIM_MOT_PROP sum),

[0061] - Total torque absorption limit T of one or more electric motors TOT,LIM_MOT_REG (T) 1,LIM_MOT_REG T 2,LIM_MOT_REG T 3,LIM_MOT_REG ;T 4,LIM_MOT_REG (the sum)

[0062] - The vehicle's total ultimate grip torque in propulsion mode.

[0063] - Total ultimate grip torque of the vehicle in regenerative mode.

[0064] Preferably, the grip limit used in the determination by the method according to the invention includes the use of a traction control algorithm (block T) TCS The calculated torque limits, and in particular, they include the ultimate grip torque T in propulsion mode. 1,TCS_PROP_OL T 2,TCS_PROP_OL T 3,TCS_PROP_OL T 4,TCS_PROP_OL and the ultimate grip torque T in regenerative mode 1,TCS_REG_OL T 2,TCS_REG_OL T 3,TCS_REG_OLT 4,TCS_REG_OL .

[0065] Therefore, the limiting torque T that can be delivered by electric motors M1, M2, M3, and M4 can be defined. n,MOT_PROP (T) 1,MOT_PROP ;T 2,MOT_PROP ;T 3,MOT_PROP ;T 4,MOT_PROP The domain of (maximum torque, considering its sign), and the torque T that can be absorbed by motors M1, M2, M3, and M4. n,MOT_REG (T) 1,MOT_REG ;T 2,MOT_REG ;T 3,MOT_REG ;T 4,MOT_REG The domain of (maximum torque, considering its sign): they are defined by the intersection between the operating limits of the motor and the required torque distribution, therefore:

[0066] Propulsion (delivery torque)

[0067]

[0068] Regeneration (absorbing torque)

[0069]

[0070] Once the torque T is known TGT,PROP (Center of gravity / Target propulsion torque), T TOT,PROP_OL T TCS,PROP_OL T TOT,MOT_PROP You can then base it on Figure 2 The diagram shown defines the correction T. PROP_CL By using proportional-integral (PI) control, based on the limiting torque P... lim,TOT_PROP_OL The correction TPROP_CL is determined by the difference between the total electrical power PACT,PROP absorbed by motors M1, M2, M3, and M4. The value of the correction TPROP_CL has an inferior saturation limit L,ISPROP, which is equal to the opposite value of the torque TTOT,PROP_OL (therefore, IS...). PROP =-T TOT,PROP_OL In this way, the value T can be avoided in every case through closed-loop control. PROP_CL +T TOT,ROP_OL (sign reversal), and the superior saturation limit (H, SSP) defined by subsequent choices and combinations. ROP In detail, by extracting the torque T TOT,MOT_PROP and T TCS,PROP_OL The upper saturation limit is defined by the minimum value between the values ​​(block MIN1). The purpose of operation is to avoid exceeding the vehicle's torque limit (T).TOT,MOT_PROP ) or grip limit (T TCS,PROP_OL If torque availability is below the value that results in a loss of grip, then torque availability becomes a limit to avoid excessive thermal and mechanical stress. Conversely, if there exists a situation where the torque limit that causes a loss of grip is reached before the available torque saturates, then the situation resulting in a loss of grip becomes a limit, because operating outside the grip limit is generally unacceptable.

[0071] The value MIN extracted from the arithmetic unit and the torque value T from the center of gravity. TGT Subtract the torque value T determined in the open loop from the middle. TOT,PROP_OL (Blocks D1 and D2). The lower result of the difference calculated at blocks D1 and D2 is extracted by the second minimum value operator (block MIN2) and becomes the upper saturation limit SS. PROP The difference D1 represents the center-of-gravity torque T determined in the open-loop circuit. TGT,PROP and torque T TOT,PROP_OL The difference between (maximum torque, considering the sign) and therefore represents the torque target T when the absorbed electrical power is below the limit of the motor. TGT,PROP The required torque difference. The difference D2 represents the torque T. TOT,PROP_OL With the maximum available center of gravity propulsion torque T TOT,MOT_PROP With the loss of grip T TCS,PROP_OL The difference between the lower torque and the previously permissible maximum center-of-gravity torque. Essentially, D2 represents the torque difference corresponding to the maximum possible increase, taking into account the delivery limits of the electric motor or the grip limits of the vehicle. Similar to what has been described previously, the upper saturation limit considers the most stringent conditions to avoid operation under critical conditions on either side.

[0072] Figure 3 and Figure 4 An example illustrates the closed-loop control action of an electric motor operating in propulsion mode. Figure 3 The diagram shows the electric power and the center of gravity torque correction T. PROP_CL As time goes by.

[0073] Before time A, the electrical power P absorbed by the motor ACT,PROP Below the limit value P lim,TOT_PROP No correction was applied to the closed-loop control. At time A, the electrical power P absorbed by the motor... ACT,PROP Exceeding the limit value P lim,TOT_PROP Closed-loop control application of torque correction T PROP_CL At time B, after time A, the electrical power P absorbed by the motor is... ACT,PROP Due to the correction T PROP_CL And become related to the limit value P lim,TOT_PROPSimilarities: Closed-loop control keeps the correction constant in order to maintain the achieved conditions.

[0074] refer to Figure 4 It shows the electrical power absorbed by the motor and the vehicle speed V. s Time diagram of center of gravity torque and torque correction.

[0075] Before time A, the center of gravity torque T TGT,PROP Below torque T TOT,PROP_OL And the electrical power P absorbed by the motor ACT,PROP Below the limit value P lim,TOT_PROP No corrections should be applied to closed-loop control.

[0076] At time A, due to the driver's operation, the center of gravity torque T TGT Exceeding torque T TOT,PROP_OL However, the electrical power P absorbed by the motor ACT,PROP Still below the limit value P lim,TOT_PROP The closed-loop control uses a correction T with an increase in positive sign. PROP_CL In order to satisfy the center of gravity torque T as much as possible. TGT,PROP Requirements.

[0077] At time B, the upper saturation limit SS is reached. PROP Therefore, T is corrected PROP_CL Stop increasing. The torque T generated by the control in both the open and closed loops. TOT,PROP_OL +T PROP_CL Restricted to T TCS,PROP_OL and T TOT,MOT_PROP The minimum value between [the two values]. The absorbed electrical power P ACT,PROP It increases at a lower rate relative to the time interval before time B (between A and B).

[0078] At time C, the electrical power P absorbed by the motor ACT,PROP Equal to the limit P lim,TOT_PROP Correction T PROP_CL It begins to decrease.

[0079] Regarding operation in regenerative mode, once the torque T is known... TGT,REG (Center of gravity / Target regenerative torque), T TOT,REG_OL T TCS,REG_OL T TOT,MOT_REG You can then base it on Figure 5 The diagram shown defines the correction T. REG_CL .

[0080] By using proportional-integral control (PI), based on the limiting power P lim,TOT_REG_OL and the total electrical power P generated by motors M1, M2, M3, and M4 ACT,REG The difference between them determines the correction TREG_CL Correction T REG_CL The value has an upper saturation limit (H, SS) REG It is equal to the torque T. TOT,REG_OL The opposite value of IS (therefore, IS) PROP =-T TOT,REG_OL This enables the prevention of the generated quantity T by closed-loop control under any circumstances. REG_CL +T TOT,REG_OL (sign reversal), and the undersaturation limit (L, IS) defined by subsequent choices and combinations. REG More specifically, by extracting the torque T TOT,MOT_REG and T TCS,REG_OL The maximum value between the values ​​(block MAX1) is used to define the undersaturation value. The purpose of the operation is to avoid exceeding the vehicle's regeneration (T). TOT,MOT_REG ) or grip (T) TCS,REG_OL Torque limit. The maximum value operator MAX1, instead of the minimum value operator as in propulsion mode, is used because of the fact that torque has a negative value in regeneration mode, and therefore the maximum value operator actually extracts the torque with the lowest absolute value.

[0081] If there exists a situation where the torque absorption capacity T of the electric motor... TOT,MOT_REG The torque absorption capacity T is determined by the absolute value of the value that results in a loss of grip, which is lower than - that is, taking the sign into account, and higher than - the value that results in a loss of grip. TOT,MOT_REG This becomes the limit in order to avoid loss of grip. Conversely, if there exists a situation where the limit of the absorbed torque is reached before the torque that can be absorbed by the motor is saturated, and beyond this limit, a loss of grip will occur (i.e., the second has a higher absolute value than the first, but is lower due to the sign), then the situation of loss of grip becomes the limit.

[0082] The value extracted from the arithmetic unit MAX1 and the regenerated torque value T from the center of gravity. TGT,REG Subtract the torque value T determined in the open loop from the middle. TOT,REG_OL (Blocks D3, D4). The highest result of the difference calculated at blocks D3 and D4 is extracted by the second maximum value operator (block MAX2) and becomes the lower saturation limit IS. REG The difference D3 represents the regenerative torque T at the center of gravity. TGT,REG With the torque T determined in the open loop TOT,REG_OL The difference between (minimum torque, considering the sign) and therefore it represents the value that satisfies the target regenerative torque T when the generated electrical power has an absolute value below the motor limit (i.e., a higher value, considering the sign). TGT,REG The required torque difference. The difference D4 represents the regenerative torque T. TOT,REG_OL With the maximum available center of gravity regeneration torque T TOT,MOT_REG and the loss of grip TTCS,REG_OL The difference between the higher values ​​of the previously permissible maximum center-of-gravity torques (considering the sign, therefore the lower absolute value). This torque difference corresponds to the maximum possible reduction (considering the sign) taking into account the delivery limit of the electric motor or the grip limit of the vehicle.

[0083] Similar to what has been described above, the lower saturation limit takes into account the most stringent conditions in order to avoid operating under critical conditions from any angle.

[0084] Figure 6 and Figure 7 An example illustrates the closed-loop control operation of a motor in regenerative mode. Figure 3 The diagram shows the electric power and the center of gravity torque correction T. PROP_CL As time goes by.

[0085] Before time A, the electrical power P generated by the motor ACT,REG Compared to the limit value P lim,TOT_REG Higher (considering the sign, but its absolute value is lower): No correction is applied to the closed-loop control. At time A, the electrical power P generated by the motor... ACT,REG It exceeds (in absolute value, but considering the sign, it is lower) the limit value P. lim,TOT_REG Closed-loop control application of torque correction T REG_CL At time B, after time A, due to the correction T REG_CL Therefore, the electrical power P absorbed by the motor ACT,REG Becomes with the limit value P lim,TOT_REG Similarities: Closed-loop control maintains constant correction, thus preserving the conditions for achievement.

[0086] refer to Figure 7 It shows a time graph of the electrical power generated by the motor, vehicle speed Vs, center of gravity torque, and torque correction.

[0087] Before time A, the center of gravity torque T TGT,REG Torque specific T TOT,REG_OL Higher (considering the sign, but lower in absolute value), and the electrical power P generated by the motor ACT,REG Compared to the limit value P lim,TOT_REG Higher (considering the sign, but lower absolute value): No correction should be applied to the closed-loop control.

[0088] At time A, due to the driver's operation, the center of gravity torque T TGT,REG Exceeding torque T TOT,REG_OL However, the electrical power P delivered by the electric motor ACT,REG Still greater than the limit value P lim,TOT_REG Higher (considering the sign, but lower in absolute value): Closed-loop control applies a correction T. REG_CLIts value decreases as the negative sign decreases (the absolute value increases) in order to satisfy the center of gravity torque T as much as possible. TGT,REG Requirements.

[0089] At time B, the lower saturation limit IS is reached. REG Therefore, T is corrected REG_CL The decrease stops (absolute value increases). The torque T generated by the control in both the open and closed loops. TOT,REG_OL +T REG_CL Restricted to T TCS,REG_OL and T TOT,MOT_REG The maximum value (minimum absolute value) between these two values. The generated electrical power P ACT,REG It decreases at a slower rate (increases in absolute value) relative to the time interval before time B (between A and B).

[0090] At time C, the electrical power P generated by the motor ACT,REG Equal to the limit P lim,TOT_REG Correction T REG_CL It begins to decrease (in absolute value, but taking into account the sign, it increases).

[0091] Therefore, correct T PROP_CL and T REG_CL This should be allocated to the motor while adhering to the assumed torque distribution m. As previously stated, this does not include boundary conditions related to torque asymmetry between the right and left sides, as they are not corrected for because they are neutralized in the center-of-gravity torque on which the calculation is based, and in any case, they have been guaranteed through open-loop calculations.

[0092] Therefore, the value of the motor torque correction corresponds to the solution of the following set of equations.

[0093] Advance

[0094] (First correction part and second correction part)

[0095]

[0096] Where T n,PROP_CL The correction applied to the nth motor in propulsion mode is achieved by keeping the sign while adjusting it to the value T. n,PROP_OL Summation. From and It can be inferred that in the first and second correction sections, the torque correction on the right side of the vehicle and the torque correction on the left side of the vehicle have the same value.

[0097] regeneration

[0098] (Third and Fourth Correction Sections)

[0099]

[0100] Where T n,REG_CL The correction applied to the nth motor in regenerative mode is achieved by altering its sign with the value T. n,REG_OL Summation, where T n,PROP_CL The correction applied to the nth motor in propulsion mode is achieved by keeping the sign while adjusting it to the value T. n,PROP_OL Summation. From and It can be inferred that in the third and fourth correction sections, the torque correction on the right side of the vehicle and the torque correction on the left side of the vehicle have the same value.

[0101] According to the method of the present invention, battery safety can be improved in both propulsion and regenerative modes by correcting torque in such a way as to avoid exceeding the power limit for extended periods. Furthermore, driver satisfaction is ensured while meeting predetermined torque distribution when torque is available in the system and the battery limit is not fully saturated. In regenerative mode, the electric motor can be utilized to the maximum extent to decelerate the vehicle instead of the mechanical brakes when braking torque is available and the battery limit is not fully saturated, while also meeting predetermined torque distribution.

[0102] Of course, implementation details and embodiments may differ considerably from those already described and shown without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method for controlling the torque of one or more electric motors (M1; M2; M3; M4) in an electric powertrain of a vehicle (V), The method includes: -For each nth motor (M1; M2; M3; ... M4) defines a first reference limit value (Plim,n,prop) for the nth power flow absorbed by the nth motor, and defines a second reference limit value (Plim,n,reg) for the nth power flow generated by the nth motor for each nth motor (M1; M2; M3; M4). - Define a first total reference limit (Plim, TOT_PROP) for the absorbed power flow, including the sum of the limit values ​​(Plim, n, prop) for each nth absorbed power, and define a second total reference limit (Plim, TOT_REG) for the generated power flow, including the sum of the limit values ​​(Plim, n, reg) for each nth generated power. - The first reference extreme value (Tn,PROP_OL) of the torque Tn delivered by each nth motor is defined as (OL) as the first total limit value (Plim,TOT_PROP) of the absorbed electric power flow, and a function of the boundary condition (m,TV) established as a function of the torque Tn of one or more of the motors; and the second extreme reference value (Tn,REG_OL) of the torque Tn absorbed by each nth motor is defined as the second total limit value (Plim,TOT_REG) of the generated electric power flow, and a function of the boundary condition (m,TV) established as a function of the torque Tn of one or more of the motors. - Determine (CL) the first torque correction (TPROP_CL) to be applied to one or more first extreme reference values ​​(Tn,PROP_OL) of the torque Tn delivered by each nth motor, and calculate the second torque correction (TREG_CL) to be applied to one or more second extreme reference values ​​(Tn,REG_OL) of the torque Tn absorbed by each nth motor. - Based on the first target torque division ratio (mPROP), the first torque correction (TCL,PROP) is divided (mCL) into a first correction portion (T3,PROP_CL; T4,PROP_CL) associated with the front axle (FA) of the vehicle, and a second correction portion (T1,PROP_CL; T2,PROP_CL) associated with the rear axle (RA) of the vehicle (V). Based on the second target torque division ratio (mREG), the second torque correction (TCL,REG) is divided into a third correction portion (T3,REG_CL; T4,REG_CL) associated with the front axle (FA) of the vehicle, and a fourth correction portion (T1,REG_CL; T2,REG_CL) associated with the rear axle (RA) of the vehicle. - The first correction portion (T3,PROP_CL; T4,PROP_CL) is applied to the set of first extreme reference values ​​(T3,PROP_OL, T4,PROP_OL) of the torque delivered to the front axle (FA) by one or more corresponding electric motors (M4, M3). - The second correction portion (T1,PROP_CL; T2,PROP_CL) is applied to the set of first extreme reference values ​​(T1,PROP_OL, T2,PROP_OL) of the torque delivered to the rear axle (RA) by one or more corresponding electric motors (M1, M2). - The third correction portion (T3, REG_CL; T4, REG_CL) is applied to the set of second extreme reference values ​​(T3, REG_OL, T4, REG_OL) of the torque absorbed from the front axle (FA) by one or more corresponding electric motors (M3, M4), and - The fourth correction portion (T1,REG_CL; T2,REG_CL) is applied to the set of second extreme reference values ​​(T1,REG_OL, T2,REG_OL) of the torque absorbed from the rear axle (RA) by one or more corresponding motors (M1, M2).

2. The method according to claim 1, wherein, The first torque correction (TCL,PROP) and the second torque correction (TCL,REG) are determined as the following functions: - The first total reference extreme value (TTOT,PROP_OL) is the sum of the first reference extreme values ​​(T1,PROP_OL, T2,PROP_OL; T3,PROP_OL, T4,PROP_OL) of the torque Tn of each nth motor. - A second total extreme value reference (TTOT,REG_OL) including the sum of the second extreme value references (T1,REG_OL, T2,REG_OL; T3,REG_OL, T4,REG_OL) of the torque Tn of each nth motor. - The first total reference limit (Plim,TOT_PROP) of the absorbed power flow and the second total reference limit (Plim,TOT_REG) of the generated power flow. -Target propulsion torque (TTGT_PROP). -Target regenerative torque (TTGT_REG). - The total torque delivery limits of the one or more electric motors (T1, LIM_MOT_PROP; T2, LIM_MOT_PROP; T3, LIM_MOT_PROP; T4, LIM_MOT_PROP). - The total torque absorption limit of the one or more motors (T1,LIM_MOT_REG, T2,LIM_MOT_REG, T3,LIM_MOT_REG; T4,LIM_MOT_REG). - The ultimate total vehicle grip torque during propulsion (T1,_TCS_PROP_OL, T2,_TCS_PROP_OL, T3,_TCS_PROP_OL; T4,_TCS_PROP_OL) - The ultimate total vehicle grip torque during regeneration (T1,_TCS_REG_OL, T2,_TCS_REG_OL, T3,_TCS_REG_OL; T4,_TCS_REG_OL).

3. The method according to claim 1 or claim 2, comprising: - Define the first reference limit value of the nth electric power flow as a corresponding polynomial with the expression an,PROPTn,PROP2+bn,PROPTn,PROP+cn,PROP, where an,PROP, bn,PROP, and cn,PROP are coefficients depending on the speed of the nth motor, and Tn,PROP is the torque delivered by the nth motor. - Define the second reference limit value of the nth electric power flow as a corresponding polynomial with the expression an,REGTn,REG2+bn,REGTn,REG+cn,REG, where an,REG, bn,REG, and cn,REG are coefficients depending on the speed of the nth motor, and Tn,REG is the torque absorbed by the nth motor.

4. The method of claim 3, comprising calculating the first extreme reference value of the torque Tn of each nth motor by means of the intersection between the geometric trajectory corresponding to the first total limit value (Plim,TOT_PROP) of the absorbed electrical power flow and one or more geometric trajectories representing boundary conditions established as a function of the torque Tn of one or more of the motors.

5. The method according to any one of claims 2 to 4, wherein, The first torque correction (TCL,PROP) is determined based on the difference between the first total limit value (Plim,TOT_PROP) of the absorbed electrical power flow and the electrical power flow (PACT,ROP) absorbed by the one or more motors (M1, M2, M3, M4), and includes a lower saturation limit (ISPROP) and an upper saturation limit (SSPROP), wherein: - The lower saturation limit (ISPROP) includes the opposite value of the first total extreme value reference (TTOT,PROP_OL). The upper saturation limit (SSPROP) includes the minimum value between a first difference (D1) and a second difference (D2). The first difference is the difference between the target propulsion torque (TTGT_PROP) and the first total extreme value reference (TTOT,PROP_OL). The second difference is the difference between the minimum value of the total torque absorption limit (T1,LIM_MOT_PROP, T2,LIM_MOT_PROP, T3,LIM_MOT_PROP; T4,LIM_MOT_PROP) of one or more electric motors and the minimum value of the ultimate total vehicle grip torque during propulsion (T1,_TCS_PROP_OL, T2,_TCS_PROP_OL, T3,_TCS_PROP_OL; T4,_TCS_PROP_OL) and the first total extreme value reference (TTOT,PROP_OL).

6. The method according to any one of claims 2 to 5, wherein, The second torque correction (TCL, REG) is determined based on the difference between the second total extreme value (Plim, TOT_REG) of the generated electrical power flow and the electrical power flow (PACT, REG) generated by the one or more motors (M1, M2, M3, M4), and includes a lower saturation limit (ISREG) and an upper saturation limit (SSREG), wherein: - The upper saturation limit (SSREG) includes the opposite value of the second total extremum reference value (TTOT,REG_OL). - The lower saturation limit (ISREG) includes the maximum value between the third difference (D3) and the second difference (D4), the third difference being the difference between the regenerated target torque (TTGT_REG) and the second total extreme value reference (TTOT,REG_OL), and the fourth difference being the difference between the maximum value of the total torque absorption limit (T1,LIM_MOT_REG, T2,LIM_MOT_REG, T3,LIM_MOT_REG; T4,LIM_MOT_REG) of one or more electric motors and the maximum total vehicle grip torque in regeneration (T1,_TCS_REG_OL, T2,_TCS_REG_OL, T3,_TCS_REG_OL; T4,_TCS_REG_OL) and the second total extreme value reference (TTOT,REG_OL).

7. The method according to any one of the preceding claims, wherein, In each of the first correction section, the second correction section, the third correction section, and the fourth correction section, the torque correction on the right side of the vehicle and the torque correction on the left side of the vehicle have the same value.

8. The method according to any one of the preceding claims, comprising calculating the second extreme value reference value of the torque Tn of each nth motor by means of the intersection between the geometric trajectory corresponding to the total limit value (Plim,TOT_REG) of the generated electrical power flow and one or more geometric trajectories representing boundary conditions established as a function of the torque Tn of one or more of the motors.

9. The method according to any one of the preceding claims, wherein, The one or more boundary conditions include at least one of the following: - The relationship between the torque delivered to or absorbed from the front axle (FA) by one or more of the electric motors and the torque delivered to or absorbed from the rear axle (RA) of the vehicle by one or more of the electric motors. - The relationship between the torque delivered by the first electric motor to or absorbed from the right wheel of the vehicle axle and the torque delivered by the second electric motor to or absorbed from the left wheel of the same vehicle axle.

10. The method according to claim 9, wherein, The motor vehicle includes a first electric motor (M1) operably associated with the left rear wheel (RL), a second electric motor (M2) operably associated with the right rear wheel (RR), and a third electric motor (M3) operably associated with the front axle (FA).

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