FR3079802A1 - CONTROL SYSTEM FOR A HYBRID VEHICLE - Google Patents

Abstract

The invention relates to a control system for a powertrain for a motor vehicle comprising a first motor, thermal, a second motor, electric, and a supply battery for the second motor, the control system orchestrating the recovery of the kinetic energy during a deceleration phase, kinetic energy which is converted into electrical energy supplied to said battery to recharge it, the control system being remarkable in that it is programmed to allow the transmission of the energy of the deceleration to the battery only when the battery charge rate is less than or equal to a first given threshold value (si), said threshold value (si) being strictly less than 100% of the battery charge rate. The invention also relates to a motor vehicle provided with such a control system.

Description

CONTROL SYSTEM FOR HYBRID VEHICLE

The invention relates to the field of electric power management in a hybrid vehicle and more particularly to the strategy of recharging a battery from the recovery of kinetic energy during a deceleration phase.

The published patent document DE 103 46 213 A1 discloses a method for regulating the state of charge of an energy accumulator on a hybrid vehicle, comprising an internal combustion engine and at least one electric motor, coupled in parallel. The charged battery should be kept there at least at a certain threshold. When the state of charge drops below this threshold, the electric motor operates as a generator, driven by the heat engine, in order to recharge the battery. This document discloses a system where the state of charge (SOC) threshold is regulated as a function of the vehicle speed in order to avoid unnecessarily maintaining the state of charge of the battery high. , when the probability of braking or decelerating is high (/.e. at high speed). This is a minimum charge threshold that is continuously monitored, so that the battery can deliver the necessary energy when needed. Regardless of the minimum threshold, it can happen that the battery is full, whatever the speed of the vehicle. In this case, the so-called amenity vehicle functions which can use a negative current are no longer available.

The object of the invention is to overcome this drawback of the above-mentioned state of the art. More particularly, the invention aims to provide a powertrain control system and a vehicle, which allow in all circumstances to deliver a negative current to the organs which requires it.

The subject of the invention is a control system for a powertrain for a motor vehicle comprising a first engine, thermal, a second engine, electric, and a supply battery for the second engine, the control system orchestrating the recovery of the kinetic energy during a deceleration phase, kinetic energy which is converted into electrical energy supplied to said battery to recharge it, the control system being remarkable in that it is programmed to allow the transmission of the energy of the battery deceleration only when the battery charge rate is less than or equal to a first given threshold value, said threshold value being strictly less than 100% of the battery charge rate.

The conversion of kinetic energy to the battery is carried out by known means, whether during a deceleration phase when the driver's foot is lifted from the accelerator or when the driver brakes.

The charge is limited to a given threshold value by appropriate means, i.e. bypass to dissipation circuits, opening of the battery supply circuit, etc.

The control system includes sensors for measuring the battery charge level at all times. The level of charge or the rate of charge is the ratio or the quantity, at a given moment, of charge of the battery compared to its total charge capacity. The charge rate is expressed as a percentage, between 0 and 100%.

According to an advantageous embodiment of the invention, a second threshold value is defined, lower than the first threshold value, and the proportion of the recovered kinetic energy which is transmitted to the battery decreases progressively between the second threshold value and the first threshold value .

Thus, the control system is programmed so that, when the charge rate is below the second threshold, all the kinetic energy which is recovered is sent to the battery; above the second threshold, the kinetic energy is not sent to the battery; and when the charge rate is between the second threshold and the first threshold, the share of kinetic energy transmitted is between 100% and 0%, the control system gradually reducing this share as it approaches the first threshold.

According to an advantageous embodiment of the invention, the first threshold value is between 80 and 99% of the maximum charge capacity of the battery, and is preferably 95%, and / or the second threshold value is between 70 and 95 % of the maximum charge capacity of the battery, and is preferably 90%.

According to an advantageous embodiment of the invention, the share of kinetic energy which is transmitted to the battery decreases mainly linearly between the second threshold value and the first threshold value and the decrease is possibly smoothed in the vicinity of the threshold values. Thus, the control system linearly controls the share of kinetic energy recharging the battery.

Alternatively, an exponential or parabolic decay can also be used.

The invention also relates to a motor vehicle comprising a first engine, heat engine and a second engine, electric, and a battery supplying the second engine, remarkable in that it comprises a control system according to one of the modes of realization exposed above.

According to an advantageous embodiment of the invention, the vehicle comprises a gearbox coupled to the electric motor and the control system is programmed so that, when changing the gearbox ratio, a negative torque is applied to the electric motor, using a portion of the available battery charge.

A negative torque is a torque in the opposite direction to a torque generated by the electric motor when it is supplied with positive current. By convention, a positive current is a current which drives the engine so that the vehicle is driven in forward. Thus, a negative torque tends to slow down the electric motor.

Applying negative torque to the electric motor improves the gear change time because the synchronization of the electric motor and the gearbox output shaft is faster.

The "available charge" is the available balance between the charge rate at a given time and 100%. By limiting the charge rate to a threshold value, the available charge (when the battery has been charged) is therefore equal to the difference between 100% and the threshold value. A portion of this available charge can be used by bodies requiring a negative current, such as the electric motor during a gear change.

According to an advantageous embodiment of the invention, the portion of the available load used to apply the negative torque to the electric motor is between 0.05% and 0.15%, and is preferably 0.1%.

In general, the choice of the first threshold value and the portion delivered during a gear change will be such that at least 1000 gear changes are possible before all the available load is consumed. This allows you to never be in a situation where all the available charge is consumed, and also possibly to use the available charge for other purposes.

According to an advantageous embodiment of the invention, the vehicle comprises mechanical members transmitting the engine torque to the drive wheels forming a traction chain and a system for damping the oscillations of the traction chain, the control system being programmed to deliver to the damping system negative torque from a portion of the available battery charge.

This can be done passively, the battery serving as a damper for the torque applied to the shaft of the electric motor, or actively, with appropriate sensors on the shafts and active damping by the application of a current. very brief negative on the electric motor.

According to an advantageous embodiment of the invention, the vehicle comprises means for selecting the driving mode, the first and / or the second threshold value of the control system depending on the driving mode selected by the driver.

Thus, the vehicle may include, but not be limited to, a "sport" mode, an "economic" mode, and a "winter" mode. For example, the "sport" mode will favor brief gear changes with a large negative current applied to the heat engine during a gear change. The "economic" mode will favor the recovery of kinetic energy. The "winter" mode will favor flexible driving with slower gear changes and maximum traction on the wheel drive.

According to an advantageous embodiment of the invention, the first motor and the second motor are placed in series and the control system controls the opening or closing of a clutch coupling the two motors.

The measures of the invention are advantageous in that a maximum charge threshold is allowed for the battery, leaving an available charge which can be useful for supplying negative current to certain parts of the vehicle, in particular for driving pleasure.

Other characteristics and advantages of the present invention will be better understood from the description and the drawings, among which:

- Figure 1 describes a vehicle according to the invention;

- Figures 2 to 4 describe the operation of a control system without limiting the battery charge;

- Figures 5 to 7 describe the operation of a control system according to the invention.

Figure 1 schematically describes a vehicle 1 according to the invention. The vehicle comprises four wheels 2, two of which are driving (the rear wheels or the front wheels), driven by drive means 3 (in particular cardan shafts). These means 3 are coupled to a gearbox 4 driven by an electric motor

5. A heat engine 6 is mounted in series with the electric motor 5 and these are coupled by a clutch 7. A control system 8 according to the invention is provided. This controls the amount of energy distributed to a battery 9 supplying the motor 5. The control system can also operate the clutch 7, and control the electric motor 5.

Figures 2 to 7 each include three equivalent graphs (Figures 2, 3, 4 on the one hand and Figures 5, 6, and 7 on the other).

Figures 2 to 4 show the situation when there is no charge limit on the battery.

Figure 2 describes the recharging power of the battery which is available according to its charge rate (SOC for “state of charge”). In this example, the maximum power, represented by curve 20, is 100 kW. The power that can arbitrarily be given to the deceleration phase, represented by curve 21, is 95 kW. The two powers are constant until the approach of 100% of battery charge because no limit is imposed on them. Once the battery is fully charged, there is no more charging power available and these curves therefore fall to zero.

FIG. 3 represents, as a function of time, a phase of recharging the battery. Curve 22 is the rate of charge of the battery which gradually increases and then stabilizes at 100%. Curves 23 and 24 correspond to curves 20 and 21 in Figure 2, except that they are here as a function of time. Once the battery reaches 100% charge, the deliverable charging power is zero.

Figure 4 illustrates a gear change phase when the battery is at its maximum charge, i.e. at 100% charge. In this example, the vehicle is in the deceleration phase. Curve 25 describes the engine speed of the electric motor. The speed decreases during deceleration. At the instant ti, the driver or the automatic gearbox changes gear from second gear to third gear. The change takes place, as represented by curve 26, during a time interval between ti and t2. In t2, the third gear is locked. Curve 27, constant and zero, illustrates the negative torque which can be applied by the battery. As the charge of the available battery is zero, no negative current can be applied.

Figure 5 describes the charging power of the battery which is available according to its charge rate. In this example, the maximum power, represented by curve 30, is 100 kW. The power which is given to the deceleration phase, represented by curve 31, is 95 kW up to the second threshold denoted S2. Beyond S2, the battery recharge is progressively limited to the value of the first threshold if. In this example, S2 = 90%, s-i = 95%, and the progression is substantially linear, with a curvature in the vicinity of the two thresholds to avoid potential jolts. Thus, the "engine brake" on the foot lift will gradually disappear with the charge of the battery.

FIG. 6 represents, as a function of time, a phase of recharging the battery. Curve 32 is the rate of charge of the battery which gradually increases then stabilizes at 95%, that is to say the first threshold value. Curves 33 and 34 correspond to curves 30 and 31 in Figure 5, except that they are here as a function of time, and since the battery charge rate does not reach 100%, curve 33 remains constant at 100 kW (unlike curve 30 in Figure 5).

Figure 7 illustrates a gear change phase when the battery is at its maximum charge, i.e. at 95% charge. In this example, the vehicle is in the deceleration phase. Curve 35 describes the engine speed of the electric motor. The speed decreases during deceleration. At the instant ti, the driver or the automatic gearbox changes gear from second gear to third gear. The change takes place, as shown by curve 36, during a time interval between ti and ts. In ts, the third gear is locked. Curve 37 illustrates the negative torque that can be applied by the battery, because it has an available charge reserve. Curve 37 is therefore negative, for example parabolic, between ti and ts. To materialize the speed of the gear change compared to Figure 4, the instant ts is also shown in the figure

Claims (10)

claims 1. Control system (8) of a powertrain for a motor vehicle (1) comprising a first engine (6), thermal, a second engine (5), electric, and a battery (9) supplying the second engine , the control system (8) orchestrating the recovery of kinetic energy during a deceleration phase, kinetic energy which is converted into electrical energy supplied to said battery (9) to recharge it, the control system (8) being characterized in that it is programmed to allow the transmission of the energy of the deceleration to the battery (9) only when the charge rate of the battery (9) is less than or equal to a first given threshold value (if ), said threshold value (si) being strictly less than 100% of the charge rate of the battery (9). 2. System according to claim 1, characterized in that a second threshold value (S2) is defined, lower than the first threshold value (si), and in that the part of the recovered kinetic energy which is transmitted to the battery (9) gradually decreases between the second threshold value (S2) and the first threshold value (if). 3. System according to one of claims 1 or 2, characterized in that the first threshold value (si) is between 80 and 99% of the maximum charge capacity of the battery, and is preferably 95%, and / or the second threshold value (S2) is between 70 and 95% of the maximum charge capacity of the battery, and is preferably 90%. 4. System according to one of claims 2 or 3, characterized in that the share of kinetic energy which is transmitted to the battery (9) decreases mainly linearly between the second threshold value (S2) and the first threshold value (if ) and the decrease is possibly smoothed in the vicinity of the threshold values (si, s ₂ ). 5. Motor vehicle (1) comprising a first engine (6), thermal and a second engine (5), electric, and a battery (9) supplying the second engine (5), characterized in that it comprises a control system (8) according to one of claims 1 to 4. 6. Vehicle according to claim 5, characterized in that the vehicle comprises a gearbox (4) coupled to the electric motor (5) and the control system (8) is programmed so that, during a gear change gearbox (4) a negative torque is applied to the electric motor (5), using a portion of the available charge of the battery (9). 7. Vehicle according to claim 6, characterized in that the portion of the available load used to apply the negative torque to the electric motor (5) is between 0.05% and 0.15%, and is preferably 0.1%. 8. Vehicle according to one of claims 5 to 7, characterized in that it comprises mechanical members transmitting the engine torque to the drive wheels forming a traction chain and a system for damping the oscillations of the traction chain, the control system (8) being programmed to deliver to the damping system a negative torque from a portion of the available charge of the battery (9). 9. Vehicle according to one of claims 5 to 8, characterized in that it comprises means for selecting the driving mode, the first and / or the second threshold value (si, S2) of the control system (8) depending on the driving mode selected by the driver. 10. Vehicle according to one of claims 5 to 9, characterized in that the first motor (6) and the second motor (5) are placed in series and the control system (8) controls the opening or closing of 'a clutch (7) coupling the two motors (5, 6).