FR3140715A1 - ELECTRIC MOTORIZATION SYSTEM FOR A MOTOR VEHICLE COMPRISING AN ELECTRICALLY ACTUATED SYSTEM EQUIPPED WITH A REDUNDANT POWER SUPPLY - Google Patents

Abstract

The present invention relates to an electrified motor vehicle comprising an electrically actuated system (12), an electrical power supply system (13) comprising a first main electrical energy storage means (131) supplying an electrical traction machine of the vehicle and a first DC/DC voltage converter (132) for powering the electrically actuated system (12). According to the invention, the power supply system (13) further comprises a redundancy power supply (136) exclusively supplying the electrically actuated system (12), the redundancy power supply (136) being powered by the storage means main (131) and comprising a second DC/DC voltage converter (134) and auxiliary energy storage means (135). The invention applies to electric and hybrid motor vehicles. Figure 2.

Description

ELECTRIC MOTOR VEHICLE DRIVE SYSTEM COMPRISING AN ELECTRICALLY ACTUATED SYSTEM EQUIPPED WITH A REDUNDANCY POWER SUPPLY

The field of the invention relates to a motor vehicle comprising an electrically actuated system of the “by-wire” type equipped with a redundancy power supply. The invention applies to the power supply of a steering system and a braking system, in particular.

In a motor vehicle equipped with an electrically actuated system of the "by-wire" type, in Anglo-Saxon terms, such as for a steering or a braking system, there is no mechanical link between the control unit and the actuators. The electrical power supply of electrified vehicle systems, i.e. with an electric motor (totally or partially), must be secured in accordance with established industry standards, in particular the ISO 26262 standard ("Road vehicles - functional safety"). With reference to this standard, the ASIL D level ("Automotive Safety Integrity Level" in English) for example corresponds to a level of integrity requirement the highest that manufacturers aim to respect for the most critical systems of a motor vehicle, in particular the steering system and the electrically actuated braking system.

The power supply for these systems is usually provided with a redundant power supply to provide the electrical needs necessary at least to bring the vehicle to a safe state in the event of a failure of the main power supply.

The state of the art is known to include patent document FR-A1-3072623, which describes a method for distributing electrical energy in a motor vehicle with a thermal engine that comprises a main accumulator, an alternator, and an electrically actuated steering system electrically powered by the alternator and by the auxiliary accumulator. The electrical distribution is controlled so that the alternator recharges the auxiliary accumulator in the event of a failure to meet the needs of the electrically actuated steering system.

Also known is patent document DE10053335B4 which describes an electrical power supply system for an electrically actuated steering system comprising a main power supply and a redundancy power supply. The main power supply system, of the 42V type, directly supplies the electric steering system and the redundant power supply is of the 14V type. The redundancy power supply is activated by controlling electrical switches.

The disadvantage of this type of power supply depending on electrical switching components is that it has little energy margin in degraded operating mode, the activation of which can sometimes be erratic. The development of switch control is often very sensitive and requires precise adjustment in order to comply with safety requirements and at the same time permanent availability of the redundancy power supply. Furthermore, the switching components are particularly sensitive to thermal constraints and electrical stresses, which make it all the more difficult to comply with the functional safety requirements of an ASIL D level.

There is therefore a need to overcome the aforementioned problems. One objective of the invention is to design a power supply system whose design makes it possible to guarantee and demonstrate more easily compliance with the functional safety requirement standards of the critical systems of a motor vehicle. Another objective is to integrate a secure power supply system having a guaranteed level of availability for the nominal mode that can be activated frequently and, for the degraded mode that will be exceptional, of the order of one or two occurrences in the life of the vehicle, and which must be sufficiently reliable when the need arises.

More specifically, the invention relates to an electric motorization system for an electrified motor vehicle comprising an electrically actuated system, an electrical power supply system comprising a first main electrical energy storage means supplying an electric traction machine of the vehicle and a first DC/DC voltage converter supplied by the main storage means and connected to a main power supply terminal of the electrically actuated system.

According to the invention, the power supply system further comprises a redundant power supply exclusively supplying the electrically actuated system, the redundant power supply being supplied by the main storage means and comprising a second DC/DC voltage converter and an auxiliary energy storage means electrically supplied by the second converter, the second converter and the auxiliary storage means both being permanently electrically connected in nominal operation to an auxiliary power supply terminal of the electrically actuated system.

The motorization system according to the invention may include the following additional characteristics, alone or in combination:

- the redundancy power supply is permanently electrically connected to the main storage means in nominal operation of said main storage means;

- the second voltage converter delivers a supply voltage of between 0.5 volts and 16 volts and is controlled by a voltage regulation setpoint for maintaining the state of charge of the auxiliary storage means at a level of between 50% and 85% of the state of charge of the total capacity of the auxiliary storage means;

- the auxiliary storage means is capable of supplying all the electrical supply power of the auxiliary power supply terminal of the electrically actuated system, and the second converter is capable, in the event of a temporary voltage drop of the auxiliary storage means, of supplying part of the power required by the electrically actuated system;

- the main storage means is a battery of electrochemical cells which delivers a voltage between 120 volts and 900 volts;

- the first voltage converter delivers a supply voltage between 8 volts and 16 volts;

- the auxiliary energy storage means delivers a voltage between 13 volts and 15 volts;

- the auxiliary energy storage means is an ultra-capacitor, for example of the double electric layer type called EDLC (“Electrochemical Double Layer Capacitor” in English);

- the auxiliary energy storage means is a Lithium-ion type battery, or any other storage technology, for example Ni-mh, Lithium-Iron-Phosphate, lead type;

The invention contemplates an electrified motor vehicle comprising a drive system according to any one of the preceding embodiments, wherein the electrically actuated system is a steering system, a braking system or a parking brake system.

The invention has the advantage of removing from the redundancy power supply architecture the switching components, of the electronically controlled MOSFET type and usually used to activate the redundancy branch and based on various electronic signals whose reliability must be guaranteed to ensure availability in nominal mode and degraded mode. The redundancy branch provides a dedicated converter and electrically connected, directly and permanently in nominal operation, to an auxiliary energy storage means, preferably an ultra-capacitor, the technology of which is advantageously chosen so that it does not include an electronically controlled switch protection means.

The invention improves availability in nominal mode, which can be frequently activated, because this ultra-capacity is directly connected to the redundant power supply terminal of the electrically actuated system to be secured.

Thanks to this, the invention improves the robustness of the redundancy power supply by breaking it down into two simple systems formed by a DC/DC converter and the auxiliary storage means making it possible to meet the reliability and availability objectives contributing to an ASIL D level.

Indeed, these two components are easily validated in ASIL QM or A for the DC/DC converter, and ASIL B or C for the auxiliary storage means, and with known damage and failure modes. These components facilitate the control of system metrics, simplify a diagnosis and improve availability while respecting functional safety objectives. With this invention, the level of requirement in terms of functional safety of the redundant branch can reach, depending on the demonstration level, an ASIL C or even D level.

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

schematically represents an electric motorization system for an electrified motor vehicle according to the invention.

schematically represents the power supply system of the electrically actuated system according to the invention.

The invention relates to electrified vehicles with an electric motor comprising an electrically actuated system and an on-board power supply system intended to provide the energy necessary for the operation of the vehicle. The invention applies to electrified vehicles, i.e. with a fully electric motor and with a partially electric hybrid motor.

In , a motorization system comprising a power supply system 13 according to the invention is shown. The power supply system 13 supplies an electric traction machine 11 and at least one electrically actuated system 12 of the “by-wire” type.

The vehicle may be fully electrically powered. The electric traction machine 11 may be connected to the steered wheels by a mechanical transmission equipped with a reducer.

The vehicle may be a hybrid with a partially electric motor and may therefore also include an internal combustion engine. The electric traction machine may be coupled to the input shaft of a gearbox in which it is integrated. This method of integrating the electric traction machine is not limiting.

In the present description, an electrically actuated system 12 may be any system whose control means delivers an instruction converted into an electrical signal which controls in response one or more actuators, for example an electric motor. No mechanical actuation link is present between the control member and an actuator. Such an electrically actuated system is generally intended to act on the wheels of the vehicle.

The electrically actuated system 12 may be an electric power steering system that controls the steered wheels of the vehicle, which may be two or four wheels in number. The steering is electrically actuated and is of the “by-wire” type, that is to say that the rotation of the steering wheel of the vehicle is converted into an electrical signal used by the steering 12 which in response controls one or more electric actuators dedicated to each steered wheel so as to pivot the axis of rotation. The energy used to orient the axes of rotation of the wheels is solely electric. The steering is exclusively electrically controlled. No mechanical link is present between the wheel control member, that is to say the steering wheel, and the steered wheels.

The electrically actuated system 12 may be a braking system. A braking command, i.e. from the brake pedal, is converted into an electrical signal used by the braking system which in response controls one or more electric actuators so as to exert a braking force on the wheels.

The electrically actuated system 12 may also be a parking brake, if desired. The control member is a gear lever or button.

The power supply system 13 is designed to supply the energy requirements of the vehicle's electrical systems, the electric traction machine 11, the electrically actuated system 12 and, in general, all the systems on board the on-board network, for example computers associated with functions such as the passenger compartment temperature control system, infotainment, lighting, signaling, passive and active occupant protection and comfort functions such as massaging seats, ambient lighting as well as the computers of the electric machine and the traction battery system, where applicable, in particular.

More specifically, the power supply system 13 comprises means for storing electrical energy, typically a traction battery system, called high voltage, and a so-called accessory battery having a voltage of between 8 volts and 16 volts. The accessory battery supplies the on-board network of the vehicle, in particular when the vehicle is in so-called “standby” or standby mode (powertrain off, occupant on board or not, vehicle with doors locked or not) for example.

According to the invention, the power supply system 13 further comprises a redundancy branch dedicated exclusively to the power supply of the electrically actuated system 12.

In , the power supply system 13 according to the invention is shown comprising the redundancy power supply branch.

The power supply system 13 comprises a main electrical energy storage means 131, which may be a traction battery, which comprises energy storage elements comprising electrochemical cells, for example of the lithium-ion, Ni-mh, lithium-iron-phosphate, lead or fuel cell type. The traction battery 131 supplies the electric traction machine of the vehicle, as well as a so-called high-voltage network comprising DC/DC voltage converters for the electrical supply of the on-board systems. Other electrical components may be supplied by the high-voltage network. The traction battery is designed to provide a voltage greater than 120 volts.

In this example, the voltage of the traction battery 131 is of the 400 volt type according to the preferred embodiment. The voltage is between 350 volts and 450 volts in nominal operation, the voltage depending in particular on the level of charge state of the battery. Alternatively, the voltage may be higher, of the 800 volt type (between 700 volts and 900 volts), or even more. The power supply system 13 further comprises an on-board charger (not shown in the ) allowing the vehicle to be connected to an external energy source via a charging interface, for example a charging socket box.

In a manner known per se, the main storage system 131 may comprise electrical protection means, such as high-voltage contactors, the function of which is to isolate the battery from the other electrical systems of the vehicle. In nominal and safe operation of the traction battery, the high-voltage contactors connecting the electrical systems of the vehicle are closed. When stationary and when the vehicle is in the “OFF” contact and the vehicle is on standby (“STAND-BY”), these contactors are generally open .

The power supply system 13 comprises a main power supply branch comprising a first DC/DC voltage converter 132 provided for supplying power to a plurality of on-board systems of the vehicle, including the vehicle's computers, the electrically actuated steering, the electrically actuated braking, or even the vehicle's thermal regulation system, or the passenger compartment systems.

In the present description, given that the invention relates more specifically to the power supply of the electric steering or braking actuation system, we have shown only an electric actuation system 12 of which a main power supply terminal B1 is electrically connected to the DC power supply voltage delivered by the converter 132, in this example at low voltage in a range of values between 8 volts and 16 volts. The power supply voltage delivered by the converter 132 depends on the electrical specifications of the electrically actuation system 12 and may be of a distinct value. In all cases, the voltage level is lower than the voltage delivered by the traction battery 131 powering the converter 132.

The power supply architecture of each electrically actuated system of the vehicle for which a redundant power supply is required to meet functional safety requirements may be identical to that of the .

The power supply system 13 further comprises a redundancy power supply branch 136 comprising a second DC/DC voltage converter 134 electrically powered by the traction battery 131. The second converter 134 is electrically and permanently connected to the traction battery 131, that is to say that the second converter 134 is permanently powered by the traction battery 131 in nominal operation of the battery 131 when the latter powers the electrical systems of the vehicle.

Throughout the description, the term permanently in the sense of the electrical connection between two components, for example between the converter 134 of the redundancy power supply and the traction battery 131, means that there are no electrical switching components, of the MOSFET type, configured to activate specifically in response to a need for reconfiguration of the electrical power supply. This improves the reliability and availability of the redundancy branch. In particular, this configuration makes it possible to meet the particularly stringent ASIL D type safety requirements for electronic switching components for which the reliability of the component and the behavior of the electronic signals for controlling the switch must be guaranteed and demonstrated.

The second converter 134 supplies a supply voltage exclusively to an auxiliary energy storage means 135 and to the actuation system 12 on a second auxiliary supply terminal B2. The supply output of the converter 134 is connected to the second terminal B2.

The second converter 134 delivers a supply voltage of between 0.5 volts and 16 volts. The main function is to ensure the charging of the auxiliary storage means 135 at all times during nominal operation of the traction battery 131.

The second converter 134 is capable of delivering a voltage during the recharging phase of the traction battery 131 and as soon as the electric traction machine of the vehicle is capable of delivering a motor torque to the wheel. A variant may be to have the main converter 132 and redundant converter 134 controlled at the time of a customer request such as for example the request to unlock the vehicle, the opening of a door or any other requested functions such as infotainment.

The supply voltage delivered by the converter 134 depends on the electrical specifications of the electric actuation system 12 and may be of a different value. The voltage level is lower than the voltage delivered by the traction battery 131 powering the converter 134.

In nominal operation, the auxiliary energy storage means 135 is permanently powered by the second converter 134 and is permanently electrically connected to the auxiliary power supply terminal B2 of the electrically actuated system 12. In the exceptional case of failure of the traction battery 131, the auxiliary storage means provides the energy needs of the actuating system 12 to make the vehicle safe without the need to activate a reconfiguration of the electrical power supply connections.

The energy storage means 135 is in this preferred embodiment an ultra-capacitor. This type of capacity having a high level of reliability and safety has the advantage that it is not mandatory to integrate an electrical protection means for overcurrent and thermal safety. The absence of such a protection means facilitates validation in demonstration with regard to safety standards, in particular ASIL D.

Alternatively, the energy storage means 135 may be a lithium-ion type battery with a voltage between 13 volts and 15 volts. The energy storage means 135 may in this example be a battery module integrating an electrical protection means against thermal runaway, of the circuit breaker and/or fuse type. This protection means is conventional for lithium-ion based modules.

In this non-limiting example, the energy storage means 135 is capable of delivering current peaks that can reach, for example, 75 amperes for a period of 0.5 seconds. The storage means 135 is capable of delivering several successive current peaks depending on the demands of the driver.

The voltage converter 134 is controlled by a voltage and/or current regulation instruction according to the laws predetermined by the vehicle supervisor making it possible to maintain the energy storage means 135 charged at a target state of charge level of, for example, between 50% and 85% of its total capacity. The low and high levels are defined by several parameters such as the ambient temperature of the storage device, its technology, the power of the power steering, or even the energy to be guaranteed in the event of a failure of the main power supply.

The converter 134 and the energy storage means 135 are arranged to both supply the auxiliary power supply terminal B2 of the electrically actuated system 12. It is provided that the energy storage means 135 provides all or part of the expected power of the redundancy branch to the electrically actuated system 12. However, in the event of a voltage drop or temporary capacity of the auxiliary storage means 135 preventing it from supplying all of the electrical needs of the system 12, the voltage converter 134 is able to temporarily supply, for up to a duration of several tens of seconds, part of the power required by the electrically actuated system 12.

The power supply system 13 includes diagnostic and information means 133 making it possible to know the state of the converter 134 at any time, in particular the available power and the regulation voltage delivered to the auxiliary energy storage means 135.

These diagnostic and information means 133 also make it possible to know at any time the level of state of charge (SOC for “State of Charge” in English) and the level of aging (SOH for “State of Health” in English), also called state of health, and the level of state of function (“state of function” in English) making it possible to determine the capacity of the storage device to respond to a predefined request, characterized for example by the age of the storage device, its temperature, its charge, its internal resistance, so as to determine the electrical power supply capacity of the redundancy branch specifically for the system 12.

In this preferred embodiment, the electrically actuated system 12 is powered by a voltage of the 12 volt type. However, it is envisaged that the system 12 requires a voltage of the 18 volt, 24 volt type, or the voltages of the 48 volt standard voltage range for example. The values of the supply voltages of the converters 132 and 134 and of the auxiliary storage means 135 are adapted according to the electrical specifications. The voltage values of the redundancy branch 136 can therefore be between 8 volts and the values of the 48 volt standard for example.

The invention is described in the foregoing by way of example. It is understood that the person skilled in the art is able to produce different variant embodiments of the invention by associating, for example, the different characteristics above taken alone or in combination, without departing from the scope of the invention.

Claims (10)

An electric motor drive system for an electrified motor vehicle comprising an electrically actuated system (12), an electrical power supply system (13) comprising a first main electrical energy storage means (131) supplying an electric traction machine (11) of the vehicle and a first DC/DC voltage converter (132) supplied by the main storage means (131) and connected to a main power supply terminal (B1) of the electrically actuated system (12), characterized in that the power supply system (13) further comprises a redundancy electrical power supply (136) supplying exclusively the electrically actuated system (12), the redundancy power supply (136) being supplied by the main storage means (131) and comprising a second DC/DC voltage converter (134) and an auxiliary energy storage means (135) electrically supplied by the second converter (134), the second converter (134) and the auxiliary storage means (135) being both electrically connected permanently in nominal operation to an auxiliary power supply terminal (B2) of the electrically actuated system (12). System according to claim 1, characterized in that the redundancy power supply (136) is permanently electrically connected to the main storage means (131) in nominal operation of said main storage means (131). System according to claim 1 or 2, characterized in that the second voltage converter (134) delivers a supply voltage of between 0.5 volts and 16 volts and is controlled by a voltage regulation setpoint for maintaining the state of charge of the auxiliary storage means (135) at a level of between 50% and 85% of the state of charge of the total capacity of the auxiliary storage means (135). System according to any one of claims 1 to 3, characterized in that the auxiliary storage means (135) is capable of supplying all the electrical supply power of the auxiliary supply terminal (B2) of the electrically actuated system (12), and in that the second converter (134) is capable, in the event of a temporary voltage drop of the auxiliary storage means (135), of supplying part of the power requested by the electrically actuated system (12). System according to any one of claims 1 to 4, characterized in that the main storage means (131) is a battery of electrochemical cells (131) which delivers a voltage between 120 volts and 900 volts. System according to any one of claims 1 to 5, characterized in that the first voltage converter (132) delivers a supply voltage between 8 volts and 16 volts. System according to any one of claims 1 to 6, characterized in that the auxiliary storage means (135) delivers a voltage of between 13 volts and 15 volts. System according to any one of claims 1 to 7, characterized in that the auxiliary energy storage means (135) is an ultra-capacitor. System according to any one of claims 1 to 7, characterized in that the auxiliary energy storage means (135) is a lithium-ion type battery. An electrified motor vehicle comprising a powertrain system according to any one of claims 1 to 9, wherein the electrically actuated system (12) is a steering system, a braking system or a parking brake system.