Secure system for supplying electricity to consumers of an electric or hybrid vehicle

Abstract

Secure electrical supply system for consumers of an electric or hybrid vehicle The present invention relates to an electrical supply system for equipment of an electric or hybrid vehicle, comprising:- a traction battery (8), capable of supplying the energy necessary for the operation of an electric powertrain of the vehicle,- power switches capable of connecting the traction battery (8) to the electric powertrain of the vehicle, the electrical supply system being characterized in that it further comprises:- at least one direct current - direct current converter, connected at the input to the traction battery (8) upstream of the power switches and at the output to an on-board network of the vehicle,- a control circuit (23) for the direct current - direct current converter, and- a voltage step-down stage (21),connected at the input to the traction battery (8) and at the output to the power supply terminals of the control circuit (23). (Figure 2),

Description

Title of the invention: Secure system for supplying electricity to consumers of an electric or hybrid vehicle

[0001] The present invention relates to the fields of electricity and the automotive industry, and more specifically concerns an electrical power supply system in an electric or hybrid electric vehicle, intended to power the vehicle's equipment.

[0002] Electric or hybrid electric vehicles are very often equipped with a lithium-ion battery or equivalent technology, capable of supplying the energy necessary for an electric motor allowing the traction or propulsion of the vehicle, possibly in cooperation with a thermal engine. Such a battery is called a traction battery or high voltage battery because the maximum no-load voltage at its terminals is generally much higher than that of service batteries, usually of the order of 12V (volts). However, some service batteries deliver a voltage of the order of 48V, this value being able to also be the maximum no-load voltage of certain “high voltage” batteries.

[0003] In an electric or hybrid electric vehicle, the service battery, often lead-acid, is used to power an on-board network of the vehicle to which the vehicle's computers are connected, as well as low-voltage consumers such as windshield wiper actuators, sensors or small heating resistors. The service battery also guarantees the power supply of safety devices of the vehicle such as braking and steering systems, while the high-voltage battery, which discharges more quickly, is intended to power the vehicle's electric motor, and possibly other high-voltage equipment such as an air conditioning compressor. The electrical network to which this equipment is connected is called the vehicle's "high-voltage" network.

[0004] The service battery only needs to be changed every three to four years, and is therefore used to power at least the vehicle's consumers during long periods of non-use, i.e. when the vehicle is stationary and switched off. It is then said to be "asleep" because in reality during these periods of non-use, the vehicle's computers have modules that remain activated to monitor the vehicle's environment, such as an alarm, a communication module of a computer to receive radio signals from an ignition key, or messages from a remote server via a wireless communication network, requesting for example the sending of maintenance data or the updating of software. This consumption of vehicles during periods of non-use is also set to grow over time, particularly due to the entry of vehicles into the Internet of Things.

[0005] However, anti-pollution standards will prohibit lead batteries, which are also heavy and bulky, which will require, for example, replacing them with small lithium-ion batteries, which are very expensive and which will have to be recharged very often when the vehicle is not in use, in particular by waking it up to be able to connect a direct current - direct current converter to the high voltage battery, the converter allowing the small lithium-ion battery to be recharged. This solution is costly in terms of energy due to waking the vehicle and the procedures for checking the high voltage network before recharging the small lithium-ion battery.

[0006] The inventors have solved these drawbacks by proposing, in the French patent application with filing number FR2302259, an electrical architecture for an electric or hybrid vehicle, without a lead-acid service battery, the vehicle's on-board network being powered solely by the vehicle's high-voltage battery. For this, one or more direct current - direct current converters upstream of the switches connecting the high-voltage battery to the vehicle's high-voltage network, convert the high voltage at the battery terminals into a low voltage enabling the on-board network consumers to be powered. The direct current - direct current converters are controlled by control units, powered by the vehicle's on-board network.

[0007] The inventors have however noted that in certain cases of failure of the on-board network (for example in the event of a short circuit), the control units are likely to be stopped and not be able to restart even after the nominal voltage on the on-board network has been restored, despite the presence of a supercapacitor connected to the output of the converter(s).

[0008] The present invention aims to remedy at least in part the drawbacks of the technique by providing an electrical power supply system for equipment of an electric or hybrid vehicle, which is energy-efficient and which makes the power supply of the vehicle's equipment more reliable.

[0009] To this end, the invention proposes a system for supplying electrical power to equipment of an electric or hybrid vehicle, comprising: - a traction battery, capable of providing the energy necessary for the operation of an electric powertrain of the vehicle, - power switches capable of connecting the traction battery to the vehicle's electric powertrain, the electrical power supply system being characterized in that it further comprises: - at least one direct current - direct current converter, connected at the input to the traction battery upstream of the power switches and at the output to a network of on board the vehicle, - a control circuit for the direct current - direct current converter, and - a voltage step-down stage, connected at the input to the traction battery and at the output to power supply terminals of the control circuit.

[0010] In the invention, the traction battery is capable of operating the electric powertrain, it is therefore a battery of electric accumulators powering an inverter and an electric motor when the vehicle is running, unlike a service battery of the prior art. The battery in the invention can therefore also be understood as a propulsion battery depending on the electric motor used, this being an electric motor allowing the traction or propulsion of the vehicle, possibly in cooperation with another type of motor if the vehicle is hybrid, understood in the sense of "electric hybrid" in this application.

[0011] Furthermore, it should be noted that the terms "upstream" or "downstream" in this application refer to the relative position of electrical components or assemblies with respect to the direction of the current leaving the battery and heading towards the consumers of the vehicle. Thus, a first component is upstream of a second component if the current leaving the battery first passes through the first component then the second component before returning to the traction battery, the latter being in discharge.

[0012] In the invention, the on-board network does not need to be powered by a service battery as in the prior art. Indeed, in the invention, whether the power switches are closed or open, the on-board network is always capable of being powered by the direct current - direct current converter.

[0013] In this configuration without a service battery, in the event of a short circuit in the output stage of the direct current - direct current converter, or in the event of a short circuit in the on-board network, the voltage of the on-board network drops very low, which implies a shutdown of all the computers or control circuits powered by this network. However, thanks to the invention, in the event of such a short circuit, the control circuit of the direct current - direct current converter is not stopped because it is powered by the traction battery via the voltage step-down stage, different from the direct current - direct current converter. Once the short circuit has been removed due to a cut-off mechanism such as a fuse, a relay or a transistor, the control circuit can therefore restore the voltage of the on-board network to its nominal value.

[0014] The invention thus guarantees safe operation of the vehicle since the vehicle's safety equipment such as braking control, steering control, lighting or demisting systems are powered by the vehicle's on-board network.

[0015] It should be noted that the invention also applies in the case where the on-board network of the vehicle is powered by a service battery, in addition to the power supplied by the direct current - direct current converter. In this case, the invention makes it possible to secure the power supply to the on-board network in the event of a failure of the on-board network requiring the power supply to the on-board network to be cut off by the service battery.

[0016] The invention therefore makes it possible to maintain control and production of a nominal voltage of the on-board network via the direct current - direct current converter even in the event of a short circuit, by restoring this nominal voltage as soon as the short circuit disappears.

[0017] The direct current - direct current converter is connected as input to a first set of cells of the traction battery and the voltage step-down stage is connected as input to a second set of cells of the traction battery.

[0018] The direct current - direct current converter is connected at the input to the traction battery, that is to say it is connected to a first set of cells of the traction battery which can be all of the cells of the traction battery or only some of the cells of the traction battery. Similarly, the control circuit is connected at the input to a second set of cells of the traction battery which can be all of the cells of the traction battery or only some of the cells of the traction battery.

[0019] Preferably in the invention, the first set of cells and the second set of cells are identical and comprise all of the cells of the traction battery. By thus connecting the direct current - direct current converter and the control circuit to the terminals of the traction battery, a specific balancing device for the battery cells is dispensed with.

[0020] Furthermore, in the invention, the voltage step-down stage is preferably of the recovery converter type. Such a type of converter is also called a "flyback" converter. It has the advantage of being simple to implement. In the case of the invention, it uses components adapted to the voltage at the terminals of the traction battery. Of course, other types of voltage step-down converters can be used to implement the voltage step-down stage.

[0021] In one embodiment of the invention, the voltage step-down stage comprises at its input a branch comprising a first winding of a transformer and a switch connected in series with the first winding, the branch being connected to terminals of the second set of cells of the traction battery. This branch is called the first branch in the following.

[0022] The output of the voltage step-down stage comprises, for example, a capacitor and a resistor mounted in parallel with each other at the power supply terminals of the control circuit, the voltage step-down stage further comprising another branch comprising a second winding of the transformer and a diode mounted in series with the second winding, the other branch being connected across the capacitor. The other branch is called the second branch in the following.

[0023] Of course, as an alternative embodiment of the invention, a more elaborate recovery converter can be used.

[0024] The ratio between a number of turns of the first winding and a number of turns of the second winding, as well as a chopping frequency of the switch, are preferably determined so as to provide a nominal supply voltage to the control circuit.

[0025] In one embodiment of the invention, the direct current - direct current converter is a converter called a rest converter, intended for supplying power to the vehicle when the latter is in standby mode, the electrical power supply system further comprising at least one direct current - direct current converter called an operating converter, capable of supplying power to the on-board network of the vehicle during operating phases of the vehicle, the operating converter being connected at the input to the traction battery and at the output to the on-board network of the vehicle.

[0026] In this embodiment of the invention, without a service battery, the on-board network is powered either by the operating converter or by the rest converter, which allows energy savings.

[0027] More precisely, when the vehicle is in standby or “asleep” mode, the vehicle’s computers are powered at a minimum by the rest converter to enable them to receive, for example, activation messages only. For this purpose, the rest converter is connected upstream of the power switches, which enables it to always be powered by the first set of battery cells. It should indeed be noted that in the invention, the devices connected at the input to a set of battery cells are connected without an intermediate converter.

[0028] When a vehicle supervision device, for example the main computer of the vehicle, receives a message from an external server or a user request such as a request to unlock the vehicle, it reactivates, reactivates the other computers of the vehicle and the operating converter which in turn supplies the on-board network of the vehicle during this entire phase where the supervision device is reactivated, called the operating phase. This may correspond to a driving phase of the vehicle or a “life on board” phase during which the vehicle is stopped but where a user can use for example a multimedia environment of the vehicle.

[0029] The operating converter is connected to the battery upstream or downstream of the power switches, the latter then having to be closed during the entire operating phase in the latter case. Preferably the operating converter is connected to the battery upstream of the power switches to avoid safety constraints on maintaining the closure of the relays even when the high voltage network is not used elsewhere or is faulty.

[0030] Preferably in the invention, the rest converter is capable of providing a maximum power to the on-board network less than or equal to a maximum consumption power of the on-board network when the vehicle is in standby mode. This maximum power is determined for example by averaging the power consumed on the on-board network during the entire duration of a standby phase of the vehicle and adding a safety margin. It is significantly lower than the power required when the vehicle is in an operating phase (driving or life on board for example).Indeed, being used only in standby mode of the vehicle, the rest converter is for example sized to provide a few Watts, and at most between 10% and 30% of the nominal power of the on-board network, that is to say of the power consumed by the on-board network in nominal operation, measured for example by averaging the power consumed on the on-board network during the entire duration of an operating phase of the vehicle. This allows savings in terms of material resources (small size of the rest converter) and in energy consumption (better efficiency at low power of the rest converter).

[0031] Furthermore, preferably in this embodiment of the invention, the electrical power supply system comprises two operating converters, each connected at the input to all of the cells of the traction battery, or else connected one to a third set of cells of the traction battery and the other to a fourth set of cells of the traction battery, the third set and the fourth set forming a partition of at least part of the traction battery.

[0032] This feature makes it possible to ensure safe redundancy of the power supply to the on-board network during the operating phase, and in particular to guarantee the power supply of safety systems such as a braking system or a trajectory control system. The operating converters also operate independently, in particular they each comprise a separate control circuit, which means that in the event of a failure of one of the operating converters, this failure does not cause a malfunction of the other operating converter.

[0033] When the two operating converters are each connected to the terminals of the traction battery, a device for balancing the cells of the traction battery is not necessary.

[0034] In the case where the third set and the fourth set are distinct, preferably the third set and the fourth set each comprise half of the cells of the battery. A balancing device then makes it possible to discharge each half of the cells in a quasi-identical manner, this balancing device being able to be software and consist of activating each of the converters for an identical duration, or so that they each supply the same amount of energy to the consumers of the vehicle's on-board network. Of course, other variant embodiments of the invention are conceivable, for example with more than two operating converters, each powered by all the cells of the battery or by a subset of cells of the battery, the subsets being able to form a partition of the cells of the battery. The first, third and fourth sets of cells of the battery can in particular be entirely superimposed or two by two, or form a partition of all the cells of the battery.

[0035] Preferably in the invention, each of the operating converters is capable of supplying a nominal power to the on-board network strictly lower than a maximum consumption power of the on-board network when the vehicle is in the operating phase. Thus, when the consumers of the on-board network consume little electrical energy, only one of the operating converters, consuming little operating energy (because they are optimized in their design for small loads of the on-board network, which is the most common case in the use of a vehicle), is used to supply the on-board network. For example, the operating converters are sized to each supply half of the maximum consumption power of the on-board network, which is the electrical power supplying the on-board network necessary for the vehicle to operate in all conditions.This maximum power is measured, for example, during a driving phase when all the consumers of the on-board network are activated, and in particular the air conditioning, in extreme weather conditions. In another example, their respective nominal powers are between 50 and 90% of the maximum consumption power of the on-board network when the vehicle is in the operating phase. These are, for example, operating converters which can vary from 2kW up to 4kW (kiloWatt) of nominal power. Limiting them to 2kW instead of 4kW also saves material resources while ensuring the safety redundancy mentioned above.

[0036] The electrical power supply system according to the invention further preferably comprises an electrical energy storage member connected to the on-board network upstream of a fuse box to which consumers of the on-board network are connected. This energy storage member is for example a supercapacitor integrated in a battery pack according to the invention. It makes it possible to reduce the amplitude of current draws on the on-board network, and to smooth the current during transient phases such as in particular a switch to standby mode, in the operating phase or a change of operating converter to supply the on-board network. As a variant, this energy storage member is a small lead-free battery such as than a small lithium battery.

[0037] In the embodiment of the invention comprising one or more operating converters, the electrical power supply system according to the invention preferably further comprises a voltage step-down stage and a control circuit associated with each operating converter, each voltage step-down stage being connected at the input to the traction battery and at the output to power supply terminals of the control circuit associated with said operating converter. Of course, the voltage step-down stage is connected at the input to the terminals of the traction battery or to a subset of the cells of the traction battery.

[0038] The electrical power supply system according to the invention therefore preferably comprises a voltage step-down stage per operating converter, each operating converter having its own control circuit. This implementation is preferable because it meets robustness and safety requirements for the power supply to the on-board network, due to the independence of the converters in this implementation. Thus, the control of each of the operating converters is also robust to a short circuit on the on-board network of the vehicle. It should be noted that this implementation requires that all the operating converters be connected at the input upstream of the power switches connecting the high-voltage battery to the high-voltage network.

[0039] In an alternative embodiment, in particular when the nominal supply voltage of the control circuits of the operating converters is less than or equal to the output voltage delivered by the idle converter, the control circuits of the operating converters are supplied by the on-board network.

[0040] In another embodiment, a single voltage step-down stage supplies the control circuits of the operating converters and / or the idle converter.

[0041] In yet another embodiment variant, one of the operating converters is connected to the input downstream of the power switches, and is controlled by a control circuit powered by the on-board network itself, and not via a dedicated voltage step-down stage. In this variant, this operating converter makes it possible to precharge the input capacitors or inductances of equipment such as a charger or an inverter for controlling an electric machine, before connecting this equipment to the battery. Thus, a specific precharging system can be dispensed with, in particular if the power switches are power relays.

[0042] The invention also relates to a battery pack for an electric or hybrid vehicle, comprising a housing housing an electrical power supply system according to the invention, the battery pack comprising two high voltage connection terminals and one low voltage connection terminal. In addition to the advantages linked to the power supply system electric according to the invention, the battery pack has the advantage of securing it, by electrically isolating the high voltage components of the electrical power supply system from the vehicle chassis, and by protecting them from shocks. The operating converters and their control circuits are in particular protected in the battery pack, from the vibration and thermal stresses of the engine compartment.

[0043] Optionally, when the electrical power supply system according to the invention comprises an operating converter downstream of the power switches, the latter is arranged outside the battery pack. Finally, when the electrical power supply system according to the invention comprises two operating converters and one is dedicated to supplying the safety systems, the other being dedicated to supplying the safety and non-safety systems of the vehicle, the battery pack comprises two low-voltage connections, i.e. a low-voltage connection for supplying the safety systems and the other for supplying the safety and non-safety systems. It should be noted that the battery pack is also connected to the ground of the vehicle, to connect one of the outputs of each operating or rest converter.

[0044] The invention finally relates to a vehicle equipped with an electrical power supply system according to the invention, integrated for example in the battery pack according to the invention. The vehicle further comprises a monitoring device capable of managing the consumption of vehicle equipment during operating phases.

[0045] The battery pack according to the invention and the vehicle according to the invention have advantages similar to those of the electrical power supply system according to the invention.

[0046] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0047] [Fig.l] represents an electrical power supply system according to the invention, for equipment of an electric or hybrid vehicle, in one embodiment of the invention,

[0048] [Fig.2] represents a control unit of a direct current - current converter continuous of the power supply system of [Fig.l], powered directly by a traction battery of the power supply system, the control unit comprising a voltage step-down stage, and

[0049] [Fig.3] represents an alternative embodiment of the electrical power supply system of [Fig.l],

[0050] According to an embodiment of the invention shown [Fig.l], an electrical power supply system 1 of an electric or hybrid vehicle comprises a battery 8 of electrical accumulators connected in series, these accumulators being for example cells using Lithium-ion technology. Of course, other technologies can be used, for example that of Nickel metal hydride batteries. The battery 8 of the electrical power system 1 is a so-called traction battery, therefore "high voltage", without lead, whose power allows the operation of an electric powertrain of the vehicle. Its maximum no-load voltage is for example between 200V and 800V, in this embodiment.

[0051] The battery 8 is housed in a battery pack 3, which is a crash-resistant housing. The battery pack 3 has two high-voltage outputs 11 and 12 connected to a high-voltage network of the vehicle. In particular, the electric powertrain is connected as an input to these outputs, which are, on the one hand, a positive high-voltage connection terminal 11, connected to one end of the battery 8 via a fuse 15 and a positive power switch 14, connected in series, and, on the other hand, a negative high-voltage connection terminal 12, connected to the other end of the battery 8 via a pyroswitch 17 and a negative power switch 16, connected in series. The fuse 15 and the pyroswitch 17 are connected upstream of the power switches 14 and 16 respectively.A pre-charging system is also connected in parallel with the power switch 14, this pre-charging system comprising in series a pre-charging resistor 19 and a pre-charging switch 18. The pre-charging system makes it possible to avoid the formation of an excessively high current draw when the battery 8 is connected to a battery charger or to a charging terminal comprising input inductances or capacitances. Alternatively, in particular when the positive 14 and negative 16 power switches are produced by MOSFET transistors (for "metal-oxide-semiconductor field-effect transistor"), the electrical power supply system 1 does not comprise a pre-charging system and / or fuse devices 15, 17.

[0052] The power switches 14, 16, 18 as well as the precharging system and the fuse devices 15, 17 are elements of the electrical power supply system 1 which are integrated into the battery pack 3, which makes it possible to electrically isolate them in the engine compartment of the vehicle, and to protect them in the event of a crash.

[0053] In order to supply 14V to low voltage consumers of the vehicle, connected by electrical connections 92 to a fuse box 90, the electrical power supply system 1 comprises, in the battery block 3:

[0054] - a first direct current - direct current converter 4 or first “operating converter”, connected as an input in parallel to the battery 8 upstream of the power switches 14, 16, 18 and as an output to an on-board network 50 of the vehicle. More precisely, a first output of the first operating converter 4 is connected to a low voltage output 14V of the battery pack 3, this low voltage output 14V voltage being connected to the on-board network 50, itself connected to the fuse box 90, and a second output of the first operating converter 4 is connected to a vehicle ground.

[0055] - and a second direct current - direct current converter 6 or second "operating converter", connected as an input in parallel to the battery 8 upstream of the power switches 14, 16, 18 and as an output to the on-board network 50 of the vehicle. A first output of the second operating converter 6 is connected to the low voltage output 14V of the battery pack 3, and a second output of the second operating converter 6 is connected to the ground of the vehicle.

[0056] The first and second operating converters 4, 6 supply the on-board network 50 when the vehicle is "awake", i.e. in the operating phase. In this state, a supervision device 10 of the vehicle, for example a main computer, manages the consumption and activation of the various equipment of the vehicle, which may be low-voltage consumers such as a car radio or specific computers, as well as power devices such as an air conditioning compressor or an electric traction motor. In this embodiment of the invention, each of the first and second operating converters 4, 6 is sized to deliver 2kW in maximum operation, i.e. half of a total consumption on the on-board network 50, estimated at 4kW (these values ​​are a function of the vehicle's equipment). In other words, the efficiency of each of the operating converters 4, 6 is optimal between 0 and 2kW.

[0057] The nominal power of each operating converter 4, 6 is thus substantially equal to half the power of a standard electric vehicle converter, and provides at most 2KW in nominal operation, i.e. for example 150 amperes under 12.5V. This nominal power of a single operating converter 4, 6 is thus sufficient to power the safety systems of the vehicle and allow an emergency stop in the event of a breakdown, in particular it is greater than 1KW, and can provide at least 100A under 12.5V.

[0058] These choices make it possible to have two operating converters which, in cost, volume and weight, make it possible to save compared to two standard electric vehicle converters. Alternatively, each operating converter 4, 6 has a nominal power greater than 2kW but less than 3kW.

[0059] To supply a minimum power to the on-board network 50 when the vehicle is in standby mode, i.e. when stopped without using vehicle equipment for an extended period, the electrical power supply system 1 also comprises in the battery pack 3, a direct current - direct current converter 2 called a "rest converter", connected at the input in parallel to the battery 8 upstream of the power switches 14, 16, 18 and at the output to the on-board network 50 of the vehicle. A first output of the rest converter 2 is connected to the low voltage output 14V of the battery pack 3, and a second output of the rest converter 2 is connected to the ground of the vehicle.

[0060] The rest converter 2 allows the vehicle's computers, by the low voltage that it supplies to the on-board network 50, for example 12V, to receive requests triggering their wake-up. Being intended for the power supply in standby mode of the vehicle, it is sized to supply in nominal operation a few tens of milliamps, for example between 0.5 and 5 Watts. In other words, the efficiency of the rest converter 2 is optimized for a few Watts. Its operation is ensured by a control unit 20 shown [Fig.2].

[0061] The control unit 20 is powered directly by the traction battery 8 and is not subject to an external deactivation device, which contributes to the reliability of its power supply.

[0062] More precisely, the control unit 20 comprises a voltage step-down stage 21 capable of transforming the voltage Vbatt at the terminals of the traction battery 8 into a supply voltage Vs for a control circuit 23 of the idle converter 2, the control circuit 23 comprising, for example, a microcontroller. The supply voltage Vs of the control circuit 23 is a low voltage of, for example, between 12V and 14V. Alternatively, depending on the implementation of the control circuit 23 in particular, this voltage Vs may be lower. The voltage step-down stage 21 is a so-called "flyback" converter, i.e. with energy recovery, whose input components are sized to support the high voltage Vbatt of, for example, between 48V and 800V.

[0063] In this exemplary embodiment of the invention, the voltage step-down stage 21 comprises a galvanic isolation transformer comprising a first winding L1 of ni turns, and a second winding L2 of n2 turns.

[0064] The input of the voltage step-down stage comprises a first electrical branch on which the first winding L1 and a switch K are connected in series. More precisely, a first terminal of the first winding L1 is connected to the positive terminal of the traction battery 8, and a second terminal of the second winding L2 is connected to one of the terminals of the switch K, the other of the terminals of the switch K being connected to the negative terminal of the traction battery 8.

[0065] A second electrical branch of the voltage step-down stage comprises the second winding L2 as well as a diode D.

[0066] The second winding L2 comprises a first terminal connected to the cathode of the diode D, the anode of the diode D being connected to a first terminal of a capacitor C connected in parallel with a resistor R. A second terminal of the second winding L2 is connected to a second terminal of the capacitor C. The capacitor C and the resistor R are connected to the output of the voltage step-down stage. 21, to the power supply terminals of the control circuit 23. In particular, a negative power supply terminal of the control circuit 23 is connected to the second terminal of the capacitor C, and a positive power supply terminal of the control circuit 23 is connected to the first terminal of the capacitor C.

[0067] When the switch K closes, a current il flows in the first branch, and the transformer is charged with electrical energy. Then when the switch K opens, the current il being cancelled, the electrical energy stored in the transformer results in the appearance of a current i2 flowing in the second winding L2 and charging the capacitor C, producing the supply voltage Vs of the control circuit 23.

[0068] This voltage Vs is equal to the nominal supply voltage of the control circuit 23. It is achieved by determining an adequate ratio between the number of turns ni of the first winding L1 and the number of turns n2 of the second winding L2, as well as an appropriate chopping frequency of the switch K.

[0069] The ratio between the number of turns of the first winding L1 and the number of turns of the second winding is for example 20. The chopping frequency is for example of the order of 100KHz (Hertz).

[0070] Thanks to this power supply, the control circuit 23 of the rest converter 2 is always powered and therefore always able to operate the rest converter to maintain a voltage at the output of the rest converter 2, which is sufficient for the operation of the vehicle in standby mode.

[0071] As for the operating converters 4, 6, these are activated during a transient phase of waking up of the vehicle, by the supervision device 10 which sends an activation message to corresponding control units 40, 60. The respective operation of each operating converter 4, 6 is in fact ensured by the respective control unit 40, 60, powered by the traction battery 8, inside the battery block 3 which secures these power supplies.

[0072] The control units 40, 60 each comprise a voltage step-down stage 41, 61 respectively, connected at the input to the terminals of the traction battery 8 and at the output to a control circuit of the operating converter 4, 6 respectively. The control circuits of the control units 40, 60 comprise, for example, microcontrollers.

[0073] The battery pack 3 integrates, in addition to the control units 20, 40, 60 of the rest converters 2 and operating converters 4, 6, a battery management module 32, monitoring, via sensors, the temperature and the voltage of the battery cells. The management module 32 is in particular capable of opening the power switches 14, 16, 18 in the event of a fault in the battery 8. The management module 32 is hardware and software, and may in particular comprise temperature sensors and / or one or more electronic circuits. Pre-programmed ironics.

[0074] The battery pack 3 comprises a CAN bus (from the English “Controller Area Network”) output 70 to which the control units 20, 40, 60 and the management module 32 of the battery 8 are connected. The CAN bus output 70 is connected to a CAN bus of the vehicle, bus to which the supervision device 10 is connected, which is located outside the battery pack 3. Thus the supervision device 10 can in particular send CAN messages to the control units 40, 60 to activate them in the transient phase of waking up the vehicle, or to deactivate them in the transient phase of putting the vehicle to sleep. The CAN bus also allows the supervision device 10 to communicate with the management module 32 when a user connects the vehicle to a charging terminal.

[0075] When the control units 40, 60 are activated, each is capable of operating its respective operating converter 4, 6 so that it supplies a low voltage current at its output when the voltage of the on-board network 50 is lower than a regulation setpoint voltage of the respective control unit 40 or 60. The regulation setpoint voltage of each operating converter 4, 6 is strictly higher than the voltage delivered by the rest converter 2, so that the latter does not operate during the operating phases of the vehicle, only one or two of the operating converters operating during these operating phases depending on the power required by the consumers.

[0076] It should be noted that the control unit 20 of the rest converter 2 is always activated (except in the event of complete discharge of the traction battery 8), but only operates the rest converter 2 when the voltage of the on-board network 50 is lower than a regulation setpoint voltage of the rest converter 2, strictly lower than those of the respective control units 40, 60. The regulation setpoint voltage of the rest converter 2 is for example 12V and those of the operating converters 4, 6 for example 13 to 14V.

[0077] The voltage of the on-board network 50 is measured independently by each control unit 20, 40, 60, for example the control unit 20 uses a voltage sensor 22 at the output of the rest converter 2, the control unit 40 uses a voltage sensor 42 at the output of the first operating converter 4, and the control unit 60 uses a voltage sensor 62 at the output of the second operating converter 6.

[0078] The voltage sensor 22 is part of the control circuit of the idle converter 2 and is powered by the voltage step-down stage 21, for example via a voltage divider stage, the nominal voltage of the voltage sensor being of the order of 5V in this embodiment of the invention. Similarly, the voltage sensor 42 is part of the control circuit of the operating converter 4 and the voltage sensor 62 is part of the control circuit of the converter operating 6. These sensors are therefore powered by the respective voltage step-down stages 41, 61.

[0079] The electrical power supply system 1 also comprises, integrated in the battery pack 3, a small energy storage element, for example a supercapacitor 24 of the DLC type (from the English “Double Layer Capacitance”), connected in parallel to the outputs of the rest converters 2 and operating converters 4, 6. This supercapacitor 24 makes it possible to smooth the current draws on the on-board network 50 while always guaranteeing a stable voltage on the on-board network 50, for example in the range 10.5V to 15V. The supercapacitor 24 also makes it possible to secure certain transient phases, which are for example the waking up or the sleeping of the vehicle, or the moment between the appearance of an electrical fault in one of the converters 2, 4, 6 and the melting of a fuse device internal to these components.The integration of this into the battery pack 3 makes it possible to secure the electrical power supply system 1, but also to simplify the electrical wiring of the electrical power supply system 1 and therefore its cost.

[0080] Furthermore, when there is a short circuit at the fuse box, the fuse corresponding to the faulty consumer causing this short circuit melts thanks to the electric current of several hundred amperes supplied over a short interval (less than one second) by at least one of the operating converters 4, 6 and / or the supercapacitor 24. As a variant, a pyroswitch is arranged on one of the electrical connections 92, preferably serving several consumers, which avoids oversizing the supercapacitor 24 or the operating converters 4, 6. In yet another variant, a current sensor detects such a short circuit and acts on a switch, for example a transistor, to cut the electrical connection 92 concerned.

[0081] The rest converters 2 and operating converters 4, 6 being connected upstream of the power switches 14, 16, 18, the electrical power supply system 1 of [Fig.l] makes it unnecessary to close the power switches 14, 16 in order to be able to supply the on-board network 50 via the rest converters 2 or operating converters 4, 6.

[0082] [Fig. 3] shows an electrical power supply system 111 according to the invention, which is an alternative embodiment of the embodiment of [Fig. 1]. In this alternative, the elements common to the electrical power supply system 1 are referenced in the same way and not re-detailed. The components of the electrical power supply system 111 are integrated into a battery pack 300 similar to the battery pack 3. The battery pack 300 differs only from the battery pack 3 in that the traction battery is a battery of accumulators 80 partitioned into two blocks 81 and 82 of electrical accumulators, between which a connection terminal called a midpoint makes it possible to split the power supply of the two operating converters 4, 6 in two independent power supplies. Thus the first operating converter 4 is powered by the block 81 by being connected at the input to the midpoint and to the end of the battery 80 connected to the positive high voltage connection terminal 11 via the fuse 15 and the positive power switch 14. The second operating converter 6 is powered by the block 82 by being connected at the input to the midpoint and to the end of the battery 80 connected to the negative high voltage connection terminal 12 via the pyroswitch 17 and the negative power switch 16.

[0083] The electrical power supply system 111 thus makes it possible to secure the power supply of the on-board network 50 by a redundancy of energy sources.Thus, in the event of failure of one of the accumulator blocks 81, 82, the on-board network 50 is powered by the other of the blocks 81, 82, which allows the safety systems of the vehicle to be functional while a driver of the vehicle parks it on the verge. The first and second operating converters 4, 6 are identical in this second embodiment, to allow balancing of the battery 80. In addition, the first and second operating converters 4, 6 each provide the same amount of energy to the on-board network 50 to allow this balancing, for example by alternating operation.

[0084] In this variant embodiment of the invention, the control unit 20 of the rest converter 2 is powered by the entire battery 80, the voltage step-down stage 21 of the control unit 20 being connected as an input to the terminals of the traction battery 80.

[0085] The control unit 40 of the first operating converter 4 is itself powered directly by the accumulator block 81, the voltage step-down stage 41 of the control unit 40 being connected at the input to the terminals of the accumulator block 81.

[0086] Similarly, the control unit 60 of the second operating converter 6 is powered directly by the accumulator block 82, the voltage step-down stage 61 of the control unit 60 being connected as an input to the terminals of the accumulator block 82.

[0087] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the characteristics of the different variant embodiments of the invention envisaged in this application can be combined to achieve the invention, to the extent that these variants are not incompatible with each other.

Claims

Claims

1. Electrical power supply system (1, 111) for equipment of an electric or hybrid vehicle, comprising: - a traction battery (8, 80), capable of supplying the energy necessary for the operation of an electric powertrain of the vehicle, - power switches (14, 16, 18) capable of connecting the traction battery (8, 80) to the electric powertrain of the vehicle, the electrical power supply system (1, 111) being characterized in that it further comprises: - at least one direct current - direct current converter (2), connected at the input to the traction battery (8, 80) upstream of the power switches (14, 16, 18) and at the output to an on-board network (50) of the vehicle, - a control circuit (23) for the direct current - direct current converter (2), and - a voltage step-down stage (21), connected at the input to the traction battery (8.80) and output to power supply terminals of the control circuit (23).

2. An electrical power system (1, 111) according to claim 1, wherein the direct current - direct current converter (2) is connected as an input to a first set of cells (8, 80) of the traction battery (8, 80) and the voltage step-down stage (21) is connected as an input to a second set of cells (8, 80) of the traction battery (8, 80).

3. Power supply system (1, 111) according to claim 2, wherein the voltage step-down stage (21) is of the recovery converter type.

4. An electrical power supply system (1, 111) according to claim 3, wherein the voltage step-down stage (21) comprises at its input a branch comprising a first winding (L1) of a transformer and a switch (K) connected in series with the first winding (L1), the branch being connected to terminals of the second set (8, 80) of cells of the traction battery (8, 80).

5. A power supply system (1, 111) according to claim 4, wherein the output of the voltage step-down stage (21) comprises a capacitor (C) and a resistor (R) connected in parallel with each other across the power supply terminals of the control circuit (23), the stage voltage reducer (21) further comprising another branch comprising a second winding (L2) of the transformer and a diode (D) connected in series with the second winding (L2), the other branch being connected to the terminals of the capacitor (C).

6. A power supply system (1, 111) according to claim 5, wherein the ratio between a number of turns (ni) of the first winding (L1) and a number of turns (n2) of the second winding (L2), as well as a chopping frequency of the switch (K), are determined so as to provide a nominal supply voltage to the control circuit (23).

7. Electrical power supply system (1, 111) according to any one of claims 1 to 6, further comprising an electrical energy storage member (24) connected to the on-board network (50) upstream of a fuse box (90) to which consumers of the on-board network (50) are connected.

8. Electrical power supply system (1, 111) according to any one of the preceding claims, in which the direct current - direct current converter (2) is a converter called a rest converter, intended for supplying power to the vehicle when the latter is in standby mode, the electrical power supply system (1, 111) further comprising at least one direct current - direct current converter (4, 6) called an operating converter, capable of supplying power to the on-board network (50) of the vehicle during operating phases of the vehicle, the operating converter (4, 6) being connected at the input to the traction battery (8, 80) and at the output to the on-board network (50) of the vehicle.

9. Electrical power supply system (1, 111) according to claims 2 and 8, comprising two operating converters (4, 6), each connected at input to the set of cells of the traction battery (8, 80), or else connected one (6) to a third set (82) of cells of the traction battery (80) and the other (4) to a fourth set (81) of cells of the traction battery (80), the third set (82) and the fourth set (81) forming a partition of at least a part of the traction battery (80).

10. An electrical power supply system (1, 111) according to claim 8 or 9, further comprising a voltage step-down stage (41, 61) and a control circuit associated with each operating converter (4, 6), each voltage step-down stage (41, 61) being connected at its input to the traction battery (8, 80) and at its output to power supply terminals of the control circuit associated with said operating converter.

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