FR3084026A1 - METHOD FOR CONTROLLING AN ELECTRICAL CONTROL CIRCUIT OF A MOTOR VEHICLE BRAKING SYSTEM - Google Patents

Abstract

The invention relates to a method for controlling an electrical control circuit of a motor vehicle braking system making it possible to secure the electrical supply of the braking system in the event of failure or unavailability of the main electrical supply. To this end, the method comprises a step of continuously regulating the state of charge level of an auxiliary electric energy accumulator (14) guaranteeing the execution of a braking force by the braking means (12). during at least a predetermined safe braking duration in the event of connection of the auxiliary accumulator (14) to the braking means (12), and, in the event of unavailability of the supply means (11) preventing the braking means ( 12) to exert a braking force, controlling the control circuit (13) to electrically connect the auxiliary accumulator (14) to the braking means (12).

Description

The field of the invention relates to a method of controlling a control circuit of the electric braking system of a motor vehicle allowing security of the electrical supply to the braking system.

Typically, a motor vehicle includes a brake installation that can apply a braking force by means of an electric actuator powered by an electric power system. In addition, to reduce fuel consumption or optimize the management of electrical energy in a motor vehicle, as illustrated by document FR2982540A1, it is common for vehicles to also be equipped with a second regenerative braking installation in which an electric machine connected to a train of wheels is connected to an electric energy accumulator.

These two types of brake installation undergo significant electrical stresses which can cause saturation of the supply means and a failure of the braking system.

To ensure the operability of a regenerative braking system of a vehicle, document DE102013205314A1 is known which describes a vehicle comprising, in addition to the main brake installation and the regenerative braking installation, a bypass circuit. electric consisting of a discharge resistor and connected to the electric machine of the regenerative braking system. The auxiliary circuit has the function in the event of regenerative braking to absorb excess electrical recovery power in the event of saturation of the energy accumulator. However, this system is not suitable for securing the main brake installation.

There is therefore a need to overcome the above problems. An objective of the invention is to ensure the operability of a main electrical braking installation of a vehicle.

More specifically, the invention relates to a method for controlling an electrical control circuit of a motor vehicle braking system for securing the electrical supply to the braking system, the braking system further comprising means electric braking device capable of exerting a braking force on the wheels of the vehicle, an electrical supply means for the braking means and a control unit capable of controlling the control circuit. According to the invention, the method comprises the following steps:

a step of continuously regulating the state of charge level of an auxiliary electric energy accumulator guaranteeing the execution of a braking force by the braking means for at least a predetermined safe braking duration in the event of connection of the auxiliary accumulator to the braking means,

- And, in case of unavailability of the supply means preventing the braking means from exerting a braking force, the control of the control circuit for electrically connecting the auxiliary accumulator to the braking means.

Alternatively, the method further comprises a step of continuously determining a braking time operable by the braking means as a function of the state of charge of the auxiliary accumulator and the regulating step consists to control the control circuit to operate an electric recharging of the auxiliary accumulator by an electric recharging means of the vehicle when the operable braking duration is less than or equal to the safe duration.

More specifically, the operable braking duration is calculated as a function of a predetermined current value and of a value of the amount of electrical energy available from the state of charge of the auxiliary accumulator to operate a force of braking by the braking means.

According to a variant, the method further comprises the following steps:

- continuous verification of the electrical energy production capacity by the recharging means,

- authorization of the recharging of the auxiliary accumulator by the recharging means according to the production capacity.

According to a variant of the method, when the capacity for producing electrical energy by the recharging means is saturated, the regulation step consists in controlling the control circuit so that the auxiliary accumulator is only authorized to supply only the braking means.

According to a variant of the method, when the recharging of the auxiliary accumulator is carried out, the regulation step consists in controlling the control circuit so that the auxiliary accumulator is only authorized to supply the means exclusively braking.

According to a variant of the method, the recharging means is an electric generator or a regenerative braking installation, and the operation of the electric recharging of the auxiliary accumulator consists in electrically connecting the auxiliary accumulator to the electric generator or to the regenerative braking system.

The invention also provides a vehicle braking system comprising an electric braking means capable of exerting a braking force on the wheels of the vehicle, a means of electrical supply of the braking means, a control circuit, a means charging station and a control unit able to control the control circuit. According to the invention, the system further comprises an auxiliary electric energy accumulator capable of being selectively connected to the braking means by means of the control circuit and the control unit comprises means for implementing the method according to any of the foregoing embodiments.

More specifically, the braking means is an installation of friction brakes.

The invention also relates to a motor vehicle comprising a braking system according to any one of the preceding embodiments.

Thanks to the invention, an electric brake installation of a vehicle is equipped with an auxiliary supply means, the charge level of which is regulated preventively so as to ensure safe braking performance in the event of unavailability. the main power supply means. The invention addresses the problems of electrical failure of the main supply circuit and improves the electrical supply security of an electrical brake installation. The safe duration is configured in such a way as to ensure a braking operation in order to put the vehicle to a halt safely or to allow at least one load shedding operation of equipment consuming the main supply means.

[017] Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description which follows, comprising embodiments of the invention given by way of non-limiting examples and illustrated by the appended drawings, in which :

Figure 1 schematically shows a motor vehicle braking system according to the invention;

FIG. 2 represents the functional control modules of a braking system according to the invention for implementing the control method according to the invention;

FIG. 3 represents an algorithm of a control method according to the invention making it possible to secure the electrical supply of an electric braking system of a motor vehicle.

The invention relates to motor vehicles and more particularly to a method for controlling a control circuit of a braking system making it possible to secure the electrical supply to the braking system so as to guarantee a braking time in the event of unavailability or failure of the main supply system of the brake system.

[019] Figure 1 schematically shows an embodiment of a braking system 1 according to the invention of a motor vehicle. The braking system 1 comprises a main electrical supply means 11, an electrical braking means 12, a control circuit 13, an auxiliary electrical accumulator 14, an electrical recharging means 15 and a control unit

16.

More specifically, the electrical supply means 11 is an electrical system intended to supply electrical energy to the braking means 12 under regular operating conditions of the braking system. The electrical supply means 11 comprises, for example, an electrical machine mechanically connected to the drive axis of a heat engine of the vehicle (for example a heat engine axis), or an electric energy accumulator, or a circuit. comprising an electric machine cooperating with an electric energy accumulator. The main electrical supply means delivers operating status information to the control unit 16, in particular concerning an electrical power deliverable to the braking means 12 and an alert in the event of failure.

The electric braking means 12 is an electric brake installation comprising electric actuators for exerting a braking force on a train of wheels, for example by means of disc brakes. The installation of electric brakes is entirely electric, said to be electrically controlled, or includes a conventional hydraulic circuit to exert the braking force. The braking means 12 comprise electrical supply terminals which can be connected in a first configuration of the control circuit to the main supply means 11 or in a second configuration of the control circuit to the auxiliary accumulator 14.

[022] It is also expected that the vehicle will be equipped with a regenerative braking installation in addition to the installation of electric brakes. This installation can be judiciously exploited to recharge the auxiliary accumulator 14 during a braking situation to reduce the consumption of electrical energy and limit the electrical stresses on the brake installation and its main electrical supply means.

The control circuit 13 has the function of distributing the electrical power between the main supply means 11 and at least the braking means 12. The control circuit 13 comprises switching means and voltage conversion means enabling the braking means 12 to be supplied from the main electrical supply means 11 or from the auxiliary electrical energy accumulator 14. For this purpose, the auxiliary accumulator is able to be selectively connected by means of braking 12 by the control unit as a function of an alert of failure of the supply means 11.

The auxiliary electric energy accumulator 14 is a conventional rechargeable battery module with electric cells for storing and delivering electrical energy at least by braking means 12. The accumulator 14 is for example a battery module with lithium-ion type electric cells. The primary function of the auxiliary accumulator is to supply the braking means 12 in the event of failure or unavailability of the main supply means 11. However, the auxiliary accumulator 14 can supply other electrical equipment of the vehicle by l 'through the control circuit 13, in particular for durability needs of the accumulator.

The electric recharging means 15 for recharging the auxiliary accumulator 14 is an electric machine which can function as an electric generator. The electrical recharging means 15 and the supply means 11 are separate pieces of equipment or, in a variant, constitute the same system for generating electrical energy.

[026] Finally, the control unit 16 is a calculation unit with integrated circuits comprising means for implementing a control method according to the invention making it possible to secure the electrical supply of the braking means 12. The unit For this purpose, the control 16 comprises memories allowing the recording of a program containing the instructions for executing the control method when it is executed by the control unit. The control unit can be integrated into the braking system or be integrated into a centralized control unit for the vehicle responsible for coordinating the electronic equipment of the powertrain.

[027] Figure 2 schematically shows a functional control module 20 of the braking system for securing the power supply. The control module 20 is implemented by the brake system control unit and comprises modules 21, 22, 23, 24. The function of the control module 20 is to continuously regulate the state of charge level of the auxiliary electrical energy accumulator so as to guarantee the execution of a braking force by the braking means for at least a predetermined safe braking duration DS in the event of the auxiliary accumulator being connected to the braking means .

[028] More specifically, the first module 21 has the function of continuously determining an amount of available energy QFR of the state of charge of the auxiliary accumulator for the electrical needs of the braking means. On the basis of a status signal SOC_ACCU representative of the state of charge of the auxiliary accumulator, the first module 21 delivers an information signal representative of the quantity of available energy QFR, depending in particular on other needs to be guaranteed if necessary. For example, the state of charge of the auxiliary accumulator for the needs of electric braking is limited between a low threshold and a high threshold to guarantee the durability of the accumulator and other electrical needs.

The function of the second module 22 is to continuously determine an operable braking duration D_FR by the braking means as a function of the state of the quantity of electrical energy available QFR of the state of charge of the accumulator auxiliary for the needs of the braking means. More specifically, the operable braking duration D_FR is calculated from a value of quantity of energy QFR and a value of a current consumed l_m by the braking means. The value of the electric current consumed l_m is a predetermined value recorded in the memory of the control unit corresponding to the maximum value of the current consumed by the electric machine to provide the braking torque necessary for emergency braking. This value is determined in vehicle design and depends in particular on the technology of the braking means and the mass of the vehicle.

For example, the value of the operable braking duration is calculated according to the following formula: D_FR = QFR / 100 * C_ACCU / I_m, in which QFR is the value of the amount of electrical energy available for braking needs expressed as a percentage of the total capacity of the accumulator (%), C_ACCU is the capacity of the auxiliary accumulator expressed in Ampere hours (Ah) and l_m is the electric current consumed expressed in Ampere (A).

[031] The third authorization module 23 has the function of determining the state of a control signal AUT_REC authorizing the activation of an electrical recharge of the auxiliary accumulator by the means for recharging the braking system or by the regenerative braking system. The control signal AUT_REC is determined as a function of a status signal ET_ALT representative of the level of production of electrical energy with respect to the maximum production capacity of the recharging means or of the regenerative braking installation.

According to one embodiment of the module 23, the status signal ET_ALT is the signal of the opening duty cycle of the excitation circuit of an alternator equipping the main supply means or the recharging means. When this status signal is less than a predetermined threshold value recorded in the memory of the control unit, for example 100% or less as a function of a production margin, then the authorization to recharge by the alternator is issued . Otherwise, recharging is prohibited. In another embodiment of the module 23, the status signal ET_ALT further includes an information signal representative of the electrical generation capacities of the regenerative braking installation.

The fourth regulation module 24 has the function of determining the state of a control signal to continuously regulate the state of charge level of the auxiliary electric energy accumulator. To this end, the module 24 emits an activation / deactivation control signal REC_EN of the electric recharge to control the braking system control circuit as a function of the operable braking duration D_FR relative to the predetermined safe braking duration. DS. The safe braking duration DS is a parameter saved in memory of the brake system control unit, the value of which is sufficient to allow the execution of a load shedding operation on consumer equipment drawing electrical energy from from the energy supplied by the supply means, or to apply a predetermined number of emergency braking phases making it possible to stop the vehicle in the event of failure of the supply means.

[034] Preferably, the fourth module 24 also has the function of transmitting a control signal MD of the supply mode of the auxiliary accumulator. The control signal MD controls the control circuit so that the auxiliary accumulator supplies the braking means exclusively, or other electrical equipment of the vehicle in addition to the braking means. The state of the control signal MD is a function of the control signal AUT_REC and of the value of the operable braking duration D_FR with respect to the safe braking duration DS.

[035] Figure 3 is a flowchart representing an algorithm of the control method according to the invention for securing the electrical supply of the braking means. The method executed by the control unit continuously regulates in advance the state of charge level of the auxiliary accumulator to guarantee the execution of a braking force by the braking means for at least the safe braking duration predetermined in case of electrical connection of the auxiliary accumulator.

More specifically, to control the regulation of the state of charge by anticipation, the method comprises a step E31 of continuous verification, by the third authorization module, of the capacity for producing electrical energy by means for recharging the auxiliary accumulator, then issues an AUT_REC authorization for recharging the auxiliary accumulator by the recharging means according to the production capacity. In the event of saturation of the production of electrical energy, the control signal AUT_REC prohibits the recharging operation and, in the event of production capacity exceeding the instantaneous electrical consumption, the control signal authorizes the recharging operation.

[037] In addition, the method comprises a step of determining E32 continuously, by the second module of the control unit, of the operable braking duration D_FR by the braking means as a function of the state of charge of the auxiliary accumulator. The operable braking duration D_FR is calculated from the value of the quantity of energy Q.FR and the value of a current consumed l_m by the braking means.

[038] Then, the method comprises a step E33 of regulating the state of charge of the auxiliary accumulator as a function of the operable braking duration D_FR with respect to the predetermined safe braking duration DS and of the control signal AUT_REC. During the regulation step 33, the fourth regulation module controls the control signals for the electric recharge REC_EN and for the power supply mode MD of the auxiliary accumulator.

[039] More precisely, in a first case, the control unit controls the control circuit to operate an electric charging step E34 of the auxiliary accumulator by the electric charging means of the vehicle, or by the braking installation. regenerative during a deceleration phase, when the operable braking duration D_FR is less than or equal to the safe duration DS. During this step, the auxiliary accumulator is not electrically connected to the supply terminals of the braking means. The electric recharging operation 34 is controlled only if the control signal AUT_REC authorizes electric recharging. In addition, to avoid reducing the operable braking time, the control circuit is preferably controlled by the control unit so that the auxiliary accumulator is only authorized to supply the braking means exclusively.

In a second case, when the operable braking duration D_FR is greater than the safe duration DS, during a step 35 the control unit does not pilot an electric recharging operation of the auxiliary accumulator by the means of recharging. In addition, in a variant, provision is made to authorize the electrical supply of other electrical equipment of the vehicle from the auxiliary accumulator as long as the operable braking duration is greater than the safe duration.

[041] In a third case, when the control signal AUT_REC prohibits an electric recharge by the recharging means or by the regenerative braking installation, during a step 36 the control unit does not authorize the command d '' an electric recharge. In addition, the control unit controls the control circuit so that the auxiliary accumulator is only authorized to supply the braking means exclusively in order to limit the electrical consumption.

[042] Finally, in the event of failure or unavailability of the main supply means, the method provides the following steps for switching the electrical supply to the braking means. More specifically, the control unit controls the control circuit to disconnect the supply terminals of the braking means from the main supply means and then electrically connect the supply terminals of the braking means to the auxiliary accumulator. In the event of saturation of the main supply means preventing the correct functioning of the braking means, the switching of the electric supply is effective during the execution of a load shedding operation of an electric consumer supplied by the supply means main.

Claims (10)

1. Method for controlling an electrical control circuit (13) of a braking system (1) of a motor vehicle for securing the electrical supply of the braking system, the braking system further comprising an electric braking means (12) capable of exerting a braking force on the wheels of the vehicle, an electrical supply means (11) of the braking means (12) and a control unit (16) capable of driving the control circuit (13), the method being characterized in that it comprises the following stages: - a continuous regulation step (E33) of the state of charge level of an auxiliary electric energy accumulator (14) guaranteeing the execution of a braking force by the braking means (12) for at least a predetermined safe braking time (DS) when the auxiliary accumulator (14) is connected to the braking means (12), - And, in the event of unavailability of the supply means (11) preventing the braking means (12) from exerting a braking force, the control of the control circuit (13) for electrically connecting the auxiliary accumulator (14 ) by braking means (12). 2. Method according to claim 1, characterized in that it further comprises a step of determining (E32) continuously an operable braking duration (D_FR) by the braking means (12) as a function of the state charging the auxiliary accumulator (14) and in that the regulating step (E33) consists in controlling the control circuit (13) to operate an electric recharging (E34) of the auxiliary accumulator (14) by a means of electric recharging (15) of the vehicle when the operable braking duration (D_FR) is less than or equal to the safe duration (DS). 3. Method according to claim 2, characterized in that the operable braking duration (D_FR) is calculated as a function of a predetermined current value (l_m) and of a quantity of electrical energy quantity (Q.FR) available from the state of charge of the auxiliary accumulator (14) to operate a braking force by the braking means (12). 4. Method according to claim 2 or 3, characterized in that it further comprises the following steps: - continuous verification (E31) of the capacity for producing electrical energy by the recharging means (15), - Authorizing the recharging of the auxiliary accumulator (14) by the recharging means (15) according to the production capacity. 5. Method according to claim 4, characterized in that, when the capacity for producing electrical energy by the recharging means (15) is saturated, the regulation step (E33) consists in controlling (E36) the circuit of control (13) so that the auxiliary accumulator (14) is only authorized to supply exclusively the braking means (12). 6. Method according to any one of claims 2 to 5, characterized in that, when the recharging of the auxiliary accumulator (14) is carried out, the regulation step (E33) consists in controlling the control circuit (13 ) so that the auxiliary accumulator (14) is only authorized to supply exclusively the braking means (12). 7. Method according to any one of claims 2 to 6, characterized in that the recharging means (15) is an electric generator or a regenerative braking installation, and in that the operation of the electric recharging (E34) of the auxiliary accumulator (14) consists in electrically connecting the auxiliary accumulator (14) to the electric generator or to the regenerative braking installation. 8. Vehicle braking system (1) comprising an electrical braking means (12) capable of exerting a braking force on the wheels of the vehicle, an electrical supply means (11) of the braking means (12), a circuit control (13), an electrical recharging means (15) and a control unit (16) able to control the control circuit (13), characterized in that it further comprises an auxiliary electric energy accumulator ( 14) capable of being selectively connected to the braking means (12) via the control circuit (13) and in that the control unit (16) includes means for implementing the method according to one any of claims 1 to 7. 9. Braking system according to claim 8, characterized in that the braking means (12) is an installation of friction brakes. 10. Motor vehicle, characterized in that it comprises a braking system according to claim 8 or 9.