Method for distributing the electrical energy of a battery

Abstract

A method (1) for distributing the electrical energy of a battery in an electric vehicle comprising a front axle and a rear axle, each axle being composed of an assembly including an electric machine and an inverter, said vehicle further comprising control means; said method (1) comprising the steps of: Determining (10a, 10b) the maximum torque supported by each inverter and electric machine assembly, by the overall front axle and the overall rear axle; Converting (11) said maximum torques into electrical power; Distributing (12) the electrical power of the battery between the three electric machines; Converting (13) the maximum power of each assembly and each axle; Limiting the driver's input (14) by the maximum available torque; Limiting the torque distribution amplitude (15) by the maximum potential torques of each electric machine. [Fig. 3]

Description

Title of the invention: Method for distributing the electrical energy of a battery

[0001] The present invention relates to the battery of a four-wheel drive electric vehicle composed of several electric machines.

[0002] The invention relates more particularly to a method of distributing the electrical energy from the battery between the electrical machines of an electric vehicle.

[0003] A four-wheel drive electric vehicle generally consists of two electric Powertrains (PWs), the first on the front axle and the second on the rear axle, and a traction battery placed centrally under the passenger compartment floor.

[0004] Electric sports vehicles consist of one electric powertrain on the front axle and two electric powertrains on the rear axle, one for each wheel. This architecture enables active torque vectoring control of the vehicle and significantly improves the vehicle's agility in corners.

[0005] However, the sum of the electrical consumption capacities of the three powertrains composing said electric sports vehicle most often exceeds the capacity of the traction battery to deliver energy, which leads to an undervoltage of said battery.

[0006] The same problem is observed, this time causing an overvoltage of the battery during battery charging operation.

[0007] These overvoltage and undervoltage phenomena are to be avoided because they prematurely degrade the traction battery.

[0008] It is therefore necessary to ensure that the cumulative electrical consumption of the various powertrains composing the electric vehicle never exceeds the electrical energy production capacity of the battery and that the cumulative electrical energy production of the powertrains never exceeds the electrical energy regeneration capacity of the battery.

[0009] In the control of chassis systems, electrical regulation and control laws, called Chassis Control laws, are then defined.

[0010] Generally, chassis control laws are implemented so that they begin by distributing the torque between the front axle and the rear axle and then distribute the rear axle torque between the right rear wheel and the left rear wheel.

[0011] However, the more freedom there is in the application of Chassis Control when distributing torque between the different electric powertrains of the vehicle, the more the agility of the motor vehicle can be improved.

[0012] For this, it is necessary to provide the Chassis Control laws with the maximum torque capacity achievable by the overall rear axle, by synthesizing the maximum torque capacities achievable by each rear electric powertrain in addition to the maximum torque capacity achievable by each electric powertrain.

[0013] Notably known is the US7325640B2 document describing a power transmission system for a four-wheel drive vehicle comprising, among other things, power transmission control means enabling the power transmission mechanism to be controlled to regulate the power output from the power transmission mechanism.

[0014] However, this document does not disclose a method for distributing the power between the different electrical machines and the two trains of the vehicle.

[0015] There is therefore a need for a control method to ensure an optimized distribution of electrical energy between the three electric machines of an electric vehicle composed of four drive wheels.

[0016] To this end, a method for distributing the electrical energy of a battery of electric accumulators of a four-wheel drive electric motor vehicle is proposed, said vehicle comprising a front axle and a rear axle, each axle being composed of at least one assembly comprising an electric machine and an inverter, said electric machines being adapted to operate in charging and discharging said battery, said vehicle further comprising control means expressing the driver's intent, said method comprising:

[0017] - A step of determining the maximum torque supported by each assembly inverter and electrical machine and by the overall front axle and the overall rear axle;

[0018] - A step of converting said maximum torques into electrical power;

[0019] - A step of distributing the electrical power of the battery between the three electrical machines;

[0020] - A step for converting the maximum powers of each set and of each train so as to obtain the maximum available torque and the maximum potential torques of each electric machine;

[0021] - A step of limiting the driver's will by the maximum torque available ;

[0022] - A step of limiting the amplitude of torque distribution by the torques po maximum potentials of each electrical machine.

[0023] Thus, the present invention does not entail any material cost and only requires the material resources already present in the vehicle.

[0024] Advantageously, said distribution step is a function of distribution criteria, said criteria being dependent on the operating mode of said battery.

[0025] Advantageously, said distribution step includes the calculation of the battery power available for the vehicle's propulsion.

[0026] Thus, the present invention makes it possible to optimize the power allocated to the three GMPs of the vehicle so as to provide driving comfort to the driver while ensuring that the battery of said vehicle is not stressed beyond its capacity.

[0027] Advantageously, the step of limiting the amplitude of torque distribution is adjusted according to the dynamics of the moving vehicle.

[0028] Thus, the method according to the invention adapts to the movements of said vehicle in order to offer an optimized torque distribution.

[0029] The invention also relates to a device for distributing the electrical energy of a battery of electric accumulators of a four-wheel drive electric motor vehicle, said vehicle comprising a front axle and a rear axle, each axle being composed of at least one assembly comprising an electric machine and an inverter, said electric machines being adapted to operate in charging and discharging said battery, said vehicle further comprising control means expressing the driver's intent, said device comprising:

[0030] - Means of determining the maximum torque supported by each assembly inverter and electrical machine and by the overall front axle and the overall rear axle;

[0031] - Means of converting said maximum torques into electrical power;

[0032] - Means of distributing the electrical power of the battery between the three electrical machines;

[0033] - Conversion means to obtain the maximum available torque and the maximum potential torques of each electrical machine;

[0034] - Means of limiting the driver's will by the maximum torque available ;

[0035] - Means of limiting the amplitude of torque distribution by the torques maximum potentials of each electric machine as a function of vehicle dynamics.

[0036] The invention also relates to a motor vehicle comprising a device as described above.

[0037] [Fig. 1] is the schematic representation of an electric vehicle comprising three GMPs according to the prior art.

[0038] [Fig.2] is a representation of the distribution of the battery's electrical power between the front axle and the rear axle.

[0039] [Fig.3] is a schematic representation of the process according to the invention.

[0040] [Fig.4] represents the time diagram of the implementation of the process according to a generator operating mode of the electrical machines.

[0041] [Fig.5] represents the time diagram of the implementation of the process according to a operating mode of electric machine motors.

[0042] The invention can be applied to any vehicle equipped with a battery and several inverter assemblies - electrical machines enabling the vehicle to be moved.

[0043] The description of the method according to the invention below relates to an embodiment of the invention in which said method is implemented within an electric vehicle as represented [Fig.1], comprising an electric battery 2 and three motor assemblies 3a, 3b, 3c, each consisting of an inverter 32a, 32b, 32c and an electric machine 31a, 31b, 31c, one on the front axle 3c and two on the rear axle 3a, 3b; i.e. three GMPs in total.

[0044] The electric vehicle is equipped with an electronic architecture comprising electronic control units, abbreviated ECUs. The electric vehicle according to the principal embodiment of the invention comprises a main electrical control unit 4a, and electronic control units for the rear left inverter 4b, rear right inverter 4d, and front inverter 4c, as well as a high-voltage battery management control unit 4e. These electronic control units enable the operation of the electrical machines, the powertrains, and the battery 2 via a CAN multiplexing bus according to the vehicle parameters.

[0045] These parameters are measured via sensors and enable, in particular, the movement of the electric vehicle.

[0046] Electrical machines can operate in two modes: motor (electrical machines receive electrical energy) and generator (electrical machines return electrical energy).

[0047] The ECU controls the transmission of electrical energy from the battery to the wheels via a motor torque, thus enabling the electric machines to operate in motor mode. The ECU also controls the transmission of braking torque from the wheels to the electric machines, allowing for the recovery of electrical energy at the battery level, also known as regenerative braking. In this case, the electric machines operate in generator mode.

[0048] The term "driver's intent" refers to the user's intentions regarding the movement of the electric vehicle, for example, an intention to accelerate. This driver's intent is expressed at least through the accelerator and brake pedals and results in acceleration or deceleration of the vehicle by means of the ECU and its "torque structure" software.

[0049] The "torque structure" unit interprets the driver's intent and calculates the total torque required at the wheels to satisfy the driver's intent.

[0050] The vehicle stability control unit then distributes the total torque calculated by the torque structure between the three electric machines, enabling the vehicle's traction.

[0051] The vehicle stability control system is responsible for torque distribution, enabling the control and optimization of vehicle acceleration along two dimensions corresponding to the dynamics of the moving vehicle:

[0052] - longitudinal acceleration: the distribution of the total torque is between the front axle and the rear axle, i.e. between the front electric machine and the rear electric machines;

[0053] - Lateral acceleration: the distribution of the total torque is between the two machines of the rear axle to optimize vehicle performance in corners. The two rear electric motors are independent; they are not physically connected by a shaft. This allows for independent control of their torque and speed. This control is called "active torque vectoring." Its principle is to decouple the torque of the right and left wheels in order to apply more torque to the outside wheel when cornering, thus increasing the vehicle's agility and turning ability.

[0054] Stability control must be as responsive as possible, chassis dynamic phenomena being on the order of a few milliseconds.

[0055] The driver's will is limited by the vehicle's capabilities and therefore by the maximum torque or power available within the vehicle's electric drive system. The total electrical power is distributed among the three electric machines. It is therefore necessary to establish maximum electrical power thresholds that each of the electric machines can use.

[0056] The thresholds of each electrical machine must take into account the following limitations:

[0057] - the available battery electrical power must remain greater than or equal to the sum of the maximum electrical power that each of the machines can use;

[0058] - the thermal, electrical and mechanical limitations of the inverter assembly and electrical machines including the de-rating corresponding to the determination step 10a of the maximum torque supported by each inverter and electrical machine assembly;

[0059] - the mechanical limitations of each train corresponding to the determination step 10b of the maximum torque supported by each train.

[0060] Derating refers to limiting the operation of electronic and electrical components below their maximum power, thereby extending their lifespan. This limitation primarily concerns the increase in the component's temperature, whose heat dissipation capacity remains difficult to improve, and mainly impacts currents and voltages. transients.

[0061] A conversion step 11 of the maximum torques obtained by the limitations of each train and each inverter / electric machine assembly takes place.

[0062] Power limitation, and consequently current limitation, causes a reduction in the generator and motor torques that electrical machines can provide. This limitation is not necessarily symmetrical for the electrical machine in generator mode or in motor mode.

[0063] Two modes of battery operation are distinguished during the movement of an electric vehicle:

[0064] - a discharge operating mode where electrical energy is transmitted from the battery to electric machines. According to this operating mode, the electric machines operate in motor mode, the motor torque is positive and the electric vehicle accelerates.

[0065] - a load-operating mode where electrical energy is transmitted from Electric motors are fed into the battery; the battery absorbs the electricity generated from the vehicle's inertia. The electric motors operate in generator mode, with a negative generator torque. During this phase, as the vehicle decelerates, it generates currents in the electric motors. This is called regenerative braking.

[0066] The maximum battery power is calculated according to these two operating modes by means of a calculation module 120 of the battery power available for the vehicle's propulsion.

[0067] The criterion for distributing the battery's electrical power between the machines depends on the battery's operating mode.

[0068] A step 12 is implemented to distribute the electrical power of the battery between the three electrical machines according to the following criteria: a. The battery operates in discharge mode:

[0069] The rear axle's electric motors are preferred; indeed, in terms of vehicle dynamics, it is more stable to accelerate with the rear axle. The maximum power allocated to the rear axle corresponds to the minimum between the maximum electrical power during battery discharge, the maximum electrical power of the entire inverter and rear electric motor assembly, and the maximum power supported by the rear axle.

[0070] The remaining discharged electrical power is allocated to the front electric motor. Thus, the maximum power allocated to the front axle corresponds to the minimum of the maximum discharged electrical power of the battery minus the maximum power allocated to the rear electric motors, the maximum electrical power of the inverter and front electric motor assembly, and the maximum power supported by the front axle. a. The battery is operating in charging mode:

[0071] The front axle electric motor is preferred; indeed, in terms of vehicle dynamics, it is more stable to brake with the front axle. The maximum power allocated to the front electric motor corresponds to the minimum between the maximum electrical power under load of the battery, the maximum electrical power of the inverter and front electric motor assembly, and the maximum power supported by the front axle.

[0072] The remaining electrical charging power of the battery is allocated to the rear electric machines. The maximum power allocated to the rear electric machines corresponds to the minimum between the maximum electrical charging power of the battery less the maximum power allocated to the front electric machine, the maximum electrical power of the inverter and rear electric machine assembly and the maximum power supported by the rear axle.

[0073] We now detail the method for calculating the maximum electrical power of the inverter and rear electrical machine assemblies.

[0074] The rear axle is equipped with two inverter and electric machine assemblies independent of each other.

[0075] This independence implies that the parameters primarily affecting the maximum electrical power of each assembly (mainly the rotational speed and temperature) may be different. Consequently, the maximum electrical power of each assembly may be different.

[0076] However, in most cases of vehicle use (excluding sporty use or strong steering), the torque distribution between the right rear GMP and the left rear GMP is close to 50 / 50 in order to reproduce the physical behavior of a mechanical differential.

[0077] If the maximum electrical power of the right rear inverter and electric machine assembly "X" is greater than the maximum electrical power of the left rear inverter and electric machine assembly "Y", i.e.: X = Y + x (1)

[0078] with x > 0

[0079] and if the maximum electrical power of the assembly of inverters and rear electrical machines is the sum X+ Y, then the maximum electrical power required from the assembly of inverters and rear right electrical machine is not achievable because the sum X + Y multiplied by 50% is greater than Y.

[0080] Indeed: (2)-

[0081] By substituting (1) into (2), or by replacing X with its expression dependent on Y in the second equation, we obtain the value of the maximum power that each The inverter and rear electric machine assembly must ensure a 50 / 50 distribution.

[0082] Z±£ = -X-^

[0083] However, the result obtained is greater than the maximum electrical power of the inverter and rear left electric machine assembly Y:

[0084] Y = Xx <X-%

[0085] To solve this problem, the minimum of the maximum electrical power of the right rear inverter and electric machine assembly X and the maximum electrical power of the left rear inverter and electric machine assembly Y (X — Y + _r) with x > 0 should be selected and then multiplied by two. In this case, no exceeding of the maximum electrical power is possible as a result of the 50 / 50 distribution.

[0086] X^Y + x^MIN[X, F] =MIN[(Y + x), F] = F

[0087] Multiplication by two and then multiplication by 50% cancel each other out, so the maximum power value of each inverter and rear electrical machine assembly must ensure during a 50 / 50 distribution will be equal to Y. This power value is well less than or equal to the respective maximum electrical powers of the right and left rear inverter and electrical machine assemblies.

[0088] Right: X = Y+x>Y

[0089] Left: Y = Y

[0090] The same reasoning applies to the calculation of the maximum power supported by the rear axle.

[0091] The lower of the maximum electrical power supported by the right rear axle and the maximum electrical power supported by the left rear axle should be selected and then multiplied by two. In this case, no exceeding of the maximum electrical power supported by each axle is possible following the 50 / 50 distribution.

[0092] This gives the maximum powers of the front and rear axles after allocation of the battery as well as the maximum powers allocated to each electric machine according to their two modes of operation (motor or generator).

[0093] Once the maximum electrical power of the battery has been distributed, it is necessary to transform the four powers calculated previously into mechanical torque in order to transfer this information to the level of the "torque structure" since this is the standard quantity in which the limitations of the "torque structure" are expressed.

[0094] Thus a conversion step 13 of maximum powers into maximum torques is implemented.

[0095] It is necessary to know the electrical / mechanical conversion efficiency of the inverter and electric machine assembly for each of the vehicle's machines, in generator mode and in motor mode. It is also necessary to know the no-load losses of each electric machine in order to estimate the maximum mechanical torque of each electric machine at zero speed.

[0096] Once the maximum torques between the front and rear train-electric machine-inverter assemblies have been calculated, the "torque structure" must take them into account in order to ensure that the overall vehicle torque setpoint never exceeds the sum of these maximum torques.

[0097] A step limiting the driver's input 14 by the maximum available torque is thus implemented. The limitation of the driver's input 14 is a function of the signal transmitted by the accelerator pedal, this limitation being a function of the maximum torques obtained during the conversion step 13.

[0098] Once the overall vehicle torque setpoint is established, the rear / front and rear left / rear right torque distributions can be readjusted according to vehicle dynamics (for example, according to the vehicle's lateral acceleration). It is then necessary to define an operating zone, here a range of variation of the maximum potential mechanical torque per electric machine in motor mode and generator mode, so that the vehicle stability control system can distribute the total mechanical wheel torque between the three electric machines.

[0099] This step corresponds to a step of limiting the amplitude of torque distribution 15 by the maximum potential torques of each electrical machine.

[0100] To do this, it is necessary to ensure that the following 5 criteria are always met:

[0101] - The sum of the redistributed torque setpoints front, rear right inverter and rear left must always be less than or equal to the consolidated overall vehicle torque setpoint;

[0102] - The forward inverter torque setpoint must always be less than or equal to the maximum potential front torque;

[0103] - The right rear inverter torque setpoint must always be less than or equal to to the maximum potential rear right torque;

[0104] - The left rear inverter torque setpoint must always be less than or equal to to the maximum potential rear left torque;

[0105] - The sum of the rear right and rear left inverter torque setpoints must always be less than or equal to the maximum potential torque of the entire inverter and rear electrical machine assembly.

[0106] Thus, the maximum potential electrical power of each electrical machine can be determined according to its mode of operation.

[0107] In motor mode the maximum potential electrical power of each machine electric is the minimum between:

[0108] - The maximum electrical power during battery discharge

[0109] - The maximum electrical power in motor mode of the inverter-machine assembly electrical in question

[0110] - The maximum electrical power supported by the train in question

[0111] This minimum is the equivalent of allocating all the electrical power of the battery in discharge on the electrical machine in question.

[0112] In generator mode, the maximum potential electrical power of each electrical machine is the minimum of:

[0113] - The maximum electrical power when charging the battery

[0114] - The maximum electrical power in generator mode of the inverter assembly- electric machine in question

[0115] - The maximum electrical power supported by the train in question

[0116] This minimum is the equivalent of allocating all the electrical power of the battery being charged to the electrical machine in question.

[0117] In the same way as before, all of these potential maximum electrical powers must be converted into potential maximum torque before this information is transmitted to the technological structure responsible for the final torque distribution between the three electric machines of the vehicle.

[0118] The technological structure responsible for the final torque distribution between the three electric machines must constantly take into account two limitations: - The limitation of overall available torque (at the level of the vehicle as a whole or only of the rear axle) - Potential torque limitations (at the level of each train or each inverter and rear electric machine assembly)

[0119] [Fig. 2] graphically represents the constraints applied for a distribution between the front and rear axles, as described above. The same representation can be used for the right rear wheel and left rear wheel distribution.

[0120] This [Fig.2] represents on the x-axis the electrical power of a front GMP and on the y-axis the electrical power of a rear GMP (right and left wheel), and allows visualization of the operating area 25, represented as a hatched area.

[0121] First, in [Fig.2] an operating zone 25, also called the "playing field", is defined, corresponding to the hatched area, defined by the following limits:

[0122] - In ordinate by the maximum potential rear power 24;

[0123] - On the x-axis by the maximum power before potential 33; and

[0124] - by a decay zone 27 corresponding to the maximum battery power.

[0125] Method 1 is adapted so that no power distribution takes place outside limits of this operating zone 25.

[0126] Fig. 2 also represents, by way of example, the maximum electrical power of the rear inverter 35 and the maximum electrical power of the front inverter 34, which correspond respectively on this graph to the maximum potential rear power 24 and the maximum potential front power 33.

[0127] Once this operating zone 25 is defined, the distribution assumptions stated above are then projected, as an example, onto a graph:

[0128] - In motor mode, the dotted lines 26 illustrate the operation of the process according to the invention which favours the rear axle. Thus, the maximum power available at the rear 29 is equal to the maximum potential rear power 24 and the remaining available battery power is allocated to the front 36, determined by the intersection of this maximum available rear power 29 with the maximum electrical power of the battery 27.

[0129] - In generator mode, the dotted lines 28 illustrate the operation according to which the method of the invention which favours the front axle. Thus the maximum power available at the front 37 is equal to the maximum potential power at the front 33 and the remaining battery power is allocated to the rear 30, determined by the intersection of this maximum power available at the front 37 with the maximum electrical power of the battery 27.

[0130] This illustrates specific cases for each operating mode that the system takes into account while leaving an infinite number of possible distributions to the chassis control as long as the point of intersection between the power allocated to the front axle and that allocated to the rear axle remains in the operating zone 25.

[0131] In other words, once the operating zone 25 is defined, the assumption of distribution by operating mode is chosen, while letting the chassis control choose for the distribution step 12, a distribution of powers within this zone 25.

[0132] All the aforementioned criteria are implemented by a process whose principle is represented [Fig.3].

[0133] This method thus allows the control of the electrical distribution between the three electric machines of a four-wheel drive electric vehicle.

[0134] The time diagrams shown [Fig.4] and [Fig.5] allow clarification of the operation of the process according to the invention illustrated [Fig.3] and are given by way of non-limiting example.

[0135] Fig. 4 represents a plurality of time diagrams according to a generator operating mode of electrical machines.

[0136] This [Fig.4] thus compares several electrical parameters for the same time abscissa:

[0137] Diagram 40: Maximum battery discharge power for traction;

[0138] Diagram 41: The maximum driving power of the entire electrical machine and inverter assembly before;

[0139] Diagram 42: the maximum driving power of the entire electric machine and right rear inverter;

[0140] Diagram 43: the maximum driving power of the entire electric machine and rear left inverter;

[0141] Diagram 44: the maximum mechanical power of the front axle motor;

[0142] Diagram 45: the maximum mechanical power of the right rear axle motor;

[0143] Diagram 46: Maximum mechanical power of the left rear axle motor

[0144] Diagram 47: the maximum engine power allocated to the front axle;

[0145] Diagram 48: the maximum engine power allocated to the virtual rear axle; and

[0146] Diagram 49: the maximum battery discharge power for traction that is actually allocated.

[0147] At=10: - The entire electrical machine assembly – rear right inverter 42 – is limited to 50 kW - The entire electrical machine assembly - rear left inverter 43 is limited to 50 kW - The entire electrical machine-inverter assembly (front 41) is limited to 70 kW - The right rear axle 45 is mechanically limited to 150 kW - The left rear axle 46 is mechanically limited to 150 kW - The front axle 44 is mechanically limited to 200 kW - The maximum electrical discharge power of the battery is 100 kW

[0148] 70 kW are allocated to the entire electrical machine - inverter assembly before it is priority over the virtual rear axle and that it is the minimum between the maximum electrical power under battery charge (100 kW), the maximum electrical power of the entire electric machine - front inverter (50 kW) and the electrical power equivalent to the maximum mechanical limitation supported by the front axle (200 kW).

[0149] 30 kW are allocated to the virtual rear axle which is the combination of the set electric machine - right rear inverter and electric machine - left rear inverter, that is, the minimum between maximum electrical power when charging the battery (100 kW) minus the maximum power allocated to the entire electric machine - front inverter (70 kW), the maximum electrical power of the most limiting electric machine - rear inverter multiplied by two ( 50 x 2 = 100 kW) and the electrical power equivalent to the mechanical limitation maximum of the most limiting rear half-axle multiplied by two (150x2 = 300 kW).

[0150] Thus, the sum of the powers allocated to the entire electric machine - front inverter (70kW) and to the virtual rear axle (30kW) is equal to the maximum charging power of the battery (100kW).

[0151] At=30: - The maximum electrical charging power of the battery is 50 kW.

[0152] 50 kW are allocated to the entire electrical machine - inverter assembly before it is priority over the virtual rear axle and it is the minimum between the maximum electrical power under battery charge (50 kW), the maximum electrical power of the entire electric machine - front inverter (70 kW) and the electrical power equivalent to the maximum mechanical limitation supported by the front axle (200 kW).

[0153] 0 kW are allocated to the virtual rear axle which is the combination of the set electric machine - right rear inverter and electric machine - left rear inverter, that is, the minimum between maximum electrical power in battery charge (50 kW) minus the maximum power allocated to the electric machine - front inverter assembly (50 kW), the maximum electrical power of the most limiting rear electric machine - inverter assembly multiplied by two (50 x 2 = 100 kW) and the equivalent electrical power to the maximum mechanical limitation of the most limiting rear half-axle multiplied by two (150 x 2 = 300 kW).

[0154] Thus, the sum of the powers allocated between the electric machine assembly - front inverter (50 kW) and the virtual rear axle (0 kW) is equal to the maximum charging power of the battery (50 kW).

[0155] At t=70: - The entire electrical machine - right rear inverter assembly is limited to 25 kW - The entire electrical machine - rear left inverter assembly is limited to 20 kW - The entire electrical machine - front inverter assembly is limited to 40 kW - The maximum electrical charging power of the battery is 100 kW.

[0156] 40 kW are allocated to the entire electrical machine - inverter assembly before it is priority over the virtual rear axle and it is the minimum between the maximum electrical charging power of the battery (80 kW), the maximum electrical power of the entire electric machine - front inverter (40 kW) and the electrical power equivalent to the maximum mechanical limitation supported by the front axle (200 kW).

[0157] 40 kW are allocated to the virtual rear axle which is the combination of the set Electric machine - right rear inverter and electric machine - left rear inverter, that is, the minimum between maximum electrical power under load of the battery (100 kW) less the maximum power allocated to the front electric machine - inverter assembly (40 kW), the maximum electrical power of the most limiting rear electric machine - inverter assembly (front left axle in this case, 20 kW) multiplied by two (20 x 2 = 40 kW) and the equivalent electrical power to the maximum mechanical limitation of the most limiting rear half axle multiplied by two (150 x 2 = 300 kW).

[0158] Thus, the sum of the powers allocated between the front electric machine-inverter assembly (40 kW) and the virtual rear axle (40 kW) is less than the maximum charging power of the battery (100 kW) because the two electric machine-inverter assemblies cannot support all the power of the battery.

[0159] Fig. 5 represents a plurality of time diagrams according to a motor operating mode of electrical machines.

[0160] This [Fig.5] thus compares several electrical parameters for the same time abscissa:

[0161] Diagram 50: Maximum battery discharge power for traction;

[0162] Diagram 51: The maximum driving power of the entire electrical machine and inverter assembly before;

[0163] Diagram 52: the maximum driving power of the entire electric machine and right rear inverter;

[0164] Diagram 53: the maximum driving power of the entire electric machine and rear left inverter;

[0165] Diagram 54: the maximum mechanical power of the front axle motor;

[0166] Diagram 55: the maximum mechanical power of the right rear axle motor;

[0167] Diagram 56: Maximum mechanical power of the left rear axle motor

[0168] Diagram 57: the maximum engine power allocated to the front axle;

[0169] Diagram 58: the maximum engine power allocated to the virtual rear axle; and

[0170] Diagram 59: the maximum battery discharge power for traction that is actually allocated.

[0171] We note, for example, that at A t=10: - The entire electric machine assembly – rear right inverter 52 – is limited to 50 kW in motor mode - The entire electric machine assembly – rear left inverter 53 – is limited to 50 kW in motor mode - The entire electric machine-inverter assembly (front 51) is limited to 70 kW in motor mode - The right rear axle 55 is mechanically limited to 150 kW - The left rear axle 56 is mechanically limited to 150 kW - The front axle 54 is mechanically limited to 200 kW - The maximum electrical discharge power of the battery is 100 kW.

[0172] 100 kW are allocated to the virtual rear axle which is the combination of the set electric machine - right rear inverter and the electric machine - left rear inverter assembly. The rear axle has priority over the electric machine - front inverter assembly. 100 kW is the minimum between the maximum electrical power during battery discharge (100 kW), twice the maximum electrical power of the most limiting rear electric machine - inverter assembly (50 x 2 = 100 kW) and the electrical power equivalent to the maximum mechanical limitation of the most limiting half of the rear axle multiplied by two (150 x 2 = 300 kW).

[0173] 0 kW are allocated to the entire electrical machine - forward inverter assembly, i.e., the minimum between maximum electrical power during battery discharge (100 kW) minus the maximum power allocated to the virtual rear axle (100 kW), the maximum electrical power of the entire electric machine - front inverter assembly (70 kW) and the electrical power equivalent to the maximum mechanical limitation supported by the front axle (200 kW).

[0174] This means that the sum of the powers allocated between the electric machine assembly - front inverter (0 kW) and the virtual rear axle (100 kW) is equal to the maximum discharge power of the battery (100kW).

[0175] At t=30: - The entire electric machine-rear right inverter assembly is limited to 55 kW in motor mode - The entire electric machine - rear left inverter assembly is limited to 50 kW in motor mode - The entire electric machine-front inverter assembly is limited to 70 kW in motor mode - The right rear axle is mechanically limited to 150 kW - The left-right train is mechanically limited to 150 kW - The front axle is mechanically limited to 200 kW - The maximum electrical discharge power of the battery is 50 kW.

[0176] 50 kW are allocated to the virtual rear axle, which is the combination of the assembly The electric motor - right rear inverter and the electric motor - left rear inverter assembly. The rear axle has priority over the electric motor - front inverter assembly. 50 kW is the minimum between the maximum electrical power during battery discharge (50 kW), twice the power maximum electrical power of the entire electrical machine - most limiting rear inverter (50 x 2 = 100 kW), in this case the limiting inverter is the rear left) and the equivalent electrical power of the maximum mechanical limitation of the most limiting rear half-axle multiplied by two (150 x 2 = 300 kW).

[0177] 0 kW are allocated to the entire electrical machine - forward inverter assembly, i.e., the minimum between maximum electrical power during battery discharge (50 kW) minus the maximum power allocated to the virtual rear axle (50 kW), the maximum electrical power of the entire electric machine - front inverter assembly (70 kW) and the electrical power equivalent to the maximum mechanical limitation supported by the front axle (200 kW).

[0178] Thus, the sum of the powers allocated between the front electric machine-inverter assembly (0 kW) and the virtual rear axle (50 kW) is equal to the maximum discharge power of the battery (50 kW).

[0179] At t=70: - The entire electric machine - right rear inverter assembly is limited to 20 kW in motor mode - The entire electric machine - rear left inverter assembly is limited to 40 kW in motor mode - The entire electric machine-front inverter assembly is limited to 40 kW in motor mode - The right rear axle is mechanically limited to 150 kW - The left-right train is mechanically limited to 150 kW - The front axle is mechanically limited to 200 kW - The maximum electrical discharge power of the battery is 100 kW.

[0180] 40 kW are allocated to the virtual rear axle, which is the combination of the assembly electric machine - right rear inverter and the electric machine - left rear inverter assembly. The rear axle has priority over the electric machine - front inverter assembly. 40 kW is the minimum between the maximum electrical power during battery discharge (100 kW), twice the maximum electrical power of the most limiting rear electric machine - inverter assembly (20 x 2 = 40 kW; in this case, the limiting inverter is the right rear one, which has a high derating), and the electrical power equivalent to the maximum mechanical limitation of the most limiting half of the rear axle multiplied by two (150 x 2 = 300 / AV).

[0181] 40 kW are allocated to the entire electrical machine - forward inverter assembly, i.e., the minimum between maximum electrical power during battery discharge (100 kW) minus the maximum power allocated to the virtual rear axle (40 kW), the maximum electrical power of the entire electric machine - front inverter assembly (40 kW) and the electrical power equivalent to the maximum mechanical limitation supported by the front axle (200 kW).

[0182] Thus, the sum of the powers allocated between the front electric machine-inverter assembly (40 kW) and the virtual rear axle (40 kW) is less than the maximum discharge power of the battery (100 kW) because the two electric machine-inverter assemblies cannot support all the power of the battery.

Claims

Demands

1. A method (1) for distributing the electrical energy of a battery of electric storage devices in a four-wheel drive electric motor vehicle, said vehicle comprising a front axle and a rear axle, each axle being composed of at least one assembly comprising an electric machine and an inverter, said electric machines being adapted to operate in charging and discharging said battery, said vehicle further comprising control means expressing the driver's intent, said method (1) comprising: - A determination step (10a, 10b) of the maximum torque supported by each inverter and electrical machine assembly taking into account the thermal, electrical and mechanical limitations of each inverter and electrical machine assembly, and by the overall front axle and the overall rear axle taking into account the mechanical limitations of each axle; - A conversion step (11) of said maximum torques into electrical power; - A distribution step (12) of the electrical power of the battery between the electrical machines during which maximum powers of each inverter and electrical machine assembly and of each train are determined as a function of said converted electrical powers, said distribution step (12) being a function of distribution criteria dependent on the operating mode of said battery,; - A conversion step (13) of the maximum powers of each assembly and each train so as to obtain the maximum available torque and the maximum potential torques of each electric machine; - A step of limiting the driver's will (14) by the maximum available torque; - A step of limiting the amplitude of torque distribution (15) by the maximum potential torques of each electrical machine.

2. Method (1) according to claim 1, characterized in that said step distribution (12) includes the calculation of the battery power available for the vehicle's propulsion.

3. Method (1) according to claim 1, characterized in that the step of limiting the amplitude of torque distribution (15) is adjusted according to the dynamics of the moving vehicle corresponding to the lateral acceleration and the longitudinal acceleration.

4. Device for distributing the electrical energy of a battery of electric accumulators of a four-wheel drive electric motor vehicle, said vehicle comprising a front axle and a rear axle, each axle being composed of at least one assembly comprising an electric machine and an inverter, said electric machines being adapted to operate in charging and discharging said battery, said vehicle further comprising control means expressing the driver's will, said device comprising: - Means of determining the maximum torque supported by each inverter and electric machine assembly taking into account the thermal, electrical and mechanical limitations of each inverter and electric machine assembly, and by the overall front axle and the overall rear axle taking into account the mechanical limitations of each axle;- Means of converting said maximum torques into electrical power; - Means of distributing the electrical power of the battery between the electrical machines configured to determine the maximum powers of each inverter and electrical machine assembly and of each train, and configured to implement the distribution according to distribution criteria dependent on the operating mode of said battery; - Means of converting the maximum powers of each assembly and each train so as to obtain the maximum available torque and the maximum potential torques of each electrical machine; - Means of limiting the driver's will by the maximum available torque; - Means of limiting the distribution amplitude of; torque by the maximum potential torques of each electric machine as a function of the vehicle dynamics.

5. Motor vehicle comprising a device according to claim 4.

Images