FR2848033A1 - Dual voltage supplying system for vehicle e.g. tourist vehicle, has control unit that controls conversion electronic transferring energy between primary and secondary networks based on states respective electrical systems - Google Patents

Abstract

System and method for power supply at two voltages, of the vehicle type, comprising a first network 7 at high voltage able to supply a first group of consumer elements 8, a second network 10 at low voltage able to supply a second group d consumer elements 11, the first network being connected to a high voltage battery 6, the second network being connected to a voltage battery 9, and electronic conversion means 12 capable of transferring energy from the first network to the second network and from the second network to the first network.

Description

i

  System and method for power supply with two voltages for a vehicle

  The invention relates to a power supply device for a motor vehicle with a combustion engine, whether it be a passenger vehicle, an industrial vehicle or a commercial vehicle, and methods for controlling such a device.

  The electrical components of a motor vehicle are electrically powered by an accumulator of electrical energy such as a battery, whose size, mass and cot increase with the electrical intensity necessary for the operation of these organs.

  Currently, a battery responds to two uses: - powering the starter motor, which requires a strong current, several hundred amperes, for a short time, a few seconds; the supply of electric charges, the engine stopped as a rotating engine, which requires lower currents of a few tens of amperes, but for a longer period.

  With the engine stopped, these charges consuming electricity in standby mode, correspond to the electronic watch, the memory circuit of the position of the seats, the alarm, etc. With the engine running, it may happen that the alternator 25 provides insufficient current to the electrical loads, so the battery must supply power.

  It is sometimes difficult, for such a battery, to meet the two requirements mentioned above with a reasonable mass and volume for the motor vehicle.

  A known solution to this problem is to replace the current single battery by two separate batteries, one of which is called "starter battery" is dedicated to the engine starter, and the other so-called "service battery" is dedicated to the supplying the electrical charges of the vehicle, these two batteries being separated by a charge management system comprising a set of controllable switches. EP-A-0 753 925 discloses a power supply device for a vehicle, having a starter battery and a service battery of equal rated voltages.

  US-A-4,743,830 discloses a dual voltage electrical system for an internal combustion engine. Two batteries are connected in series and are connected to an alternator. Both batteries have a nominal voltage of 12 volts and some electrical charges 10 are powered by 12 volts, while others are powered by 24 volts. This type of mounting may have disadvantages in the event of a fault, for example short-circuiting, of one of the two batteries.

  The 24-volt supply can then no longer be ensured.

  The invention proposes a reliable electrical system, having a high capacity for managing degraded modes and allowing optimized operation of the vehicle.

  | The two-voltage power supply system for a vehicle, according to one aspect of the invention, comprises a first high-voltage network capable of supplying a first group of consumer elements, a second low-voltage network capable of supplying a second group of consumer elements, the first network being connected to a high voltage battery, the second network being connected to a low voltage battery, and an electronic conversion means able to transfer energy from the first network; to the second network, and from the second network to the first network. A control unit is able to control the conversion means as a function of the states of the electrical system, said states being grouped under management configurations, each management configuration corresponding to a state condition of an alternator capable of supplying energy to the electrical system, in the direction of the current in each battery and in the conversion means, according to operating parameters of a vehicle equipped with said system, according to battery charging criteria, and according to criteria state of the electrical system. This allows the vehicle to start the engine even if one of the batteries is discharged.

  Advantageously, the battery charge criteria are Boolean values equal to 1 if the voltage of the corresponding battery is greater than a predetermined threshold.

  Advantageously, the state criteria of the electrical system are Boolean values equal to 1 if the voltage of the corresponding network is within a predetermined range for a strategy to be implemented.

  Advantageously, the system comprises a control unit connected to the electronic conversion means. The control unit can also be connected to a control unit of the engine.

  The control unit may include a processor, a RAM, a read only memory and control software.

  In one embodiment of the invention, the control unit comprises at least one means for controlling a first energy transfer by the conversion means of the first network to the second network, and a second energy transfer by the means for converting the second network to the first network. Optionally, said control means is adapted to control a zero energy transfer.

  The software may include means for controlling a first energy transfer from the first network to the second network when a recharge of the low voltage battery is required. The software may include means for controlling a second energy transfer from the second network to the first network when charging of the high voltage battery is required or when high power is requested on the first network.

  The software may include means for controlling a zero energy transfer when starting a heat engine.

  In some cases, the starter battery is sufficient to start the engine without the help of the service battery.

  The software may include means for smoothing transitions between modes of operation, particularly when starting or stopping the engine.

  The software may include a means for taking into account the temperature of a battery when it is recharged.

  Advantageously, the first network is powered by an alternator and supplies a starter of the engine. The first network may be connected to an alternator-starter. The control unit is connected to the alternator and the starter.

  Advantageously, the system comprises means for smoothing the transitions between modes of operation.

  In one embodiment of the invention, the electronic conversion means is a DC / DC converter whose output voltages can be modulated.

  The invention proposes a two-voltage power supply method for a vehicle, from a first high-voltage network capable of supplying a first group of consumer elements, of a second low-voltage network capable of supplying power to a vehicle. second group of consumer elements, the first network being connected to a high voltage battery, the second network being connected to a low voltage battery, and an electronic conversion means capable of transferring energy from the first network to the second network and the second network to the first network, wherein the conversion means is controlled according to states of the electrical system, said states being grouped under management configurations, each management configuration corresponding to a condition of state of an alternator capable of supplying energy to the electrical system, in the sense of the current in each battery and in the means of co nversion, according to operating parameters of a vehicle equipped with said system, according to battery charging criteria, and according to the state of the electrical system criteria.

  In one embodiment of the invention, the low voltage battery is recharged by the high voltage battery to allow the engine to start and to avoid a reset of a control unit, if the load criterion of the low voltage battery is not satisfied, or if the condition criterion of the low voltage network is not satisfied, and if the condition criterion of the high voltage network is satisfied, and if the load criterion High voltage battery is not satisfied.

  In one embodiment of the invention, the high voltage battery is recharged by the low voltage battery to increase the voltage of the high voltage battery, if the charging criterion of the high voltage battery is not satisfied. or if the condition criterion of the high voltage network is not satisfied, and if the condition criterion of the low voltage network is satisfied, and if the charging criterion of the low voltage battery is satisfied, .

  In one embodiment of the invention, the heat engine is assisted by the alternator if the load criterion of the high voltage battery is satisfied, and if the condition criterion of the high voltage network is satisfied. .

  In one embodiment of the invention, at least one battery is recharged by recovering energy from the heat engine via the alternator-starter if a gear is engaged, in the engaged position, if the engine rotates at higher idle speed, if the alternator-starter is in alternator mode, and if the accelerator pedal is released.

  In one embodiment of the invention, the engine is shut down for a short time if the state of charge of the batteries or the condition criteria of the electrical system are judged correct, then restarted if the state of battery charge or if the condition criteria of the electrical system are unsatisfactory.

  In one embodiment of the invention, if a first start-up test of the heat engine has failed, then the voltage measurement on the networks is not significant and the electrical system status criteria are not significant. more taken into account.

  The invention also makes it possible to improve the approval on board the vehicle by decreasing or even eliminating any jolts on the engine linked to a sudden energy demand during the starting of the engine and by decreasing or even by eliminating the changes perceptible by the driver and / or passengers during a shutdown of the engine when the electrical equipment is in operation, such as vehicle lights, windshield wipers, etc. The present invention will be better understood on reading the detailed description of some embodiments taken as non-limiting examples and illustrated by the appended drawings, in which: FIG. 1 is a schematic view of the system according to one embodiment; of the invention; FIG. 2 is a thermal compensation curve of the regulation voltage; and FIGS. 3 to 13 are diagrammatic views of the system configurations denoted 1 to 11 in the following, in which the direction of the currents is represented by arrows.

  As can be seen in FIG. 1, the vehicle 1 represented diagrammatically comprises, inter alia, an electrical system 2, a heat engine 3, a control unit 4 of the heat engine 3, 15 especially dedicated to the injection calculation, and a unit control unit 5 of the electrical system 2. The control units 4 and 5 are connected so that they can exchange data.

  The electrical system 2 comprises a high voltage battery, for example 36 volts, referenced 6, a high voltage electrical network 7 connected to the battery 6 and electrical energy consuming elements 8 connected to the electrical network 7, a part, and a low-voltage battery, for example 12 volts, referenced 9, a low voltage electrical network 10, connected to the battery 9, and electrical energy consuming elements It connected to the electrical network 10, 25 of somewhere else.

  The electrical system 2 further comprises a DC / DC converter 12 connected by a terminal to the high voltage electrical network 7 and by another terminal to the low voltage electrical network 10, and an alternator-starter 10 electrically connected to the electrical network 7. at high voltage and mechanically by means of a shaft 14 to the heat engine 3. The converter 12 and the starter alternator 13 are connected by a data transmission link to the control unit 5. The terminals of the batteries 6 and 9 and energy consuming elements 8 and 11, not connected respectively to the electrical networks 7 and 10, are connected to a mass of the vehicle. The converter 12 and the alternator-starter 13 can also be connected, in a manner not shown, to a mass of the vehicle. Thus, the batteries 6 and 9 are each connected to the ground and the network, respectively 7, 10, which is associated with them. The networks 7 and 10 are interconnected via the converter 12. The batteries 6 and 9 are thus arranged in parallel.

  The voltages of 36 and 12 volts are indicated here for information only. Other pairs of voltages could be provided, for example 24 volts and 12 volts, 48 volts and 12 volts, 28 volts and 14 volts, or 42 volts and 14 volts. Torques of tension are chosen according to the standards in force, the type of the vehicle and the electrical dimensioning.

  In addition, the invention is perfectly suited to conventional vehicle architectures comprising an alternator and a starter which are distinct elements, each electrically connected to the electrical network and mechanically, if necessary intermittently, to the engine.

  In what follows, we will adopt a convention on the current which is called "the banker": any current entering an element has a positive sign. The current entering the battery 6, the current entering the consumer elements 8, Ig the current entering the battery 9, the current consumed by the consuming elements 11, 113 the current entering the alternator-starter 13, 17/12 the current entering the converter 12 from the network 7 and 11 ,,, 2 the current entering the converter 12 from the network 10. Whatever the mode of operation, we have I8 and II , l 0.

  During a start of the heat engine 3, the battery 6 imposes its voltage U6 to the alternator-starter 13, and the battery 9 30 imposes the consumer element of the network 10, so we have U9 = U, 1.

  The alternator-starter 13 receives current, so we have 1j3 positive and 16 negative. The battery 9 supplies power to the network 10, so we have 19 negative. In the case where the thermal engine is in operation and where the alternator-starter 13 and the converter 12 regulate the voltage on the networks 7 and 10, the alternator-starter 13 is generator and imposes a voltage U13 on the network 7, we therefore have U7 = U13. The converter 12 is in direct mode and imposes a voltage Ul0,12 to the network 10, so we have Ul0 = U10 / 12. I13 is negative because the alternator 5 starter 13 provides power to the network 7. I6 is positive because the battery 6 receives power, except special case. 7, 12 is positive, the converter 12 receiving current from the network 7, while Io0 / 12 is negative, the converter 12 supplying power to the network 10. 19 is positive, the battery 9 receiving power, except case 10 particular.

  In the case where the heat engine 3 is in operation and / or the battery 9 charges the battery 6 via the converter 12, the alternator-starter 13 is generator and imposes a voltage U13 to the network 7. The converter is in direct mode and imposes a voltage Ul0,12 to the network 10. I6 is positive, the battery 6 receiving power. The currents 17, 12 and 11 ,, 2 are reversed with respect to the preceding case and I 9 is negative, the battery 9 supplying current adx consumers 11 and the converter 12.

  In the case where the battery 9 comes to support the battery 6 through the converter 12 to start the heat engine 3, the alternator-starter 13 is motor, so '13 is positive, the converter 12 is in mode reverse. The battery 6 and the converter 12 supply current to the alternator-starter 13 at a voltage U6 = U7,12. Thus, we also have negative 6, and negative 7, 12, while 10/12 is positive.

  The term "capacitive effect" refers to a phenomenon of drop in the no-load voltage of a battery after a high current draw.

  The capacitive effect occurs in particular after the activation of the starter on the battery 6, and if necessary on the battery 9 in the case of a diesel engine o a strong current is taken from the battery 9 by preheating. The time required for the voltage of a battery to return to its initial value depends on several factors, such as the temperature, the lower the temperature and the longer the duration, the current drawn and the state of charge of the battery . The time to return to normal varies from a few minutes to a few hours.

  The occurrence of this phenomenon will be indicated in the control unit 5 by a flag or flag located in a volatile memory with a delay effect.

  For the implementation of a strategy of charging and discharging the batteries judiciously, different criteria are used. The criteria for charging batteries rated B6 and B9, which are Booleans, indicating whether the state of charge of the corresponding battery is acceptable. Thus B6 = 1, if the state of charge of the battery 6 is greater than a threshold, and B9 = 1, if the state of charge of the battery 9 is greater than another threshold. These criteria B6 and B9 are considered relatively robust compared to the capacitive effect. Network condition criteria R7 and R10, which are also Booleans, are also used to indicate whether the operation of the networks is acceptable at the current operating point and in response to requests for supplies that are likely to follow. R7 = 1 if the voltage U7 is greater than a threshold voltage established according to a particular phase of operation. The same goes for R10 with a suitable threshold voltage. Criteria R7 and R10 are relatively dependent on the capacitive effect. Therefore, when the flag signaling a capacitive effect RAM.EFF-CAPA is 1, the criteria R7 and R10 are not taken into account. Criteria B6 and B9, R7 and R10 are used to determine the treatment to be performed as part of battery charging strategies. The different combinations are grouped into four classes called contexts: - Context 1: B6 = 1 and R7 = 1 and B9 = 1 and R10 = 1 Networks 7 and 10 are considered correct.

  - Context 2: (B6 = O or R7 = 0) and (B9 = 1 and R10 = 1) The network 7 is considered correct but not the network 10.

  - Context 3: (B6 = 1 and R7 = 1) and (B9 = O or R10 = 0) Network 10 is considered correct but not network 7.

  - Background 4: (B6 = O or R7 = 0) and (B9 = O or R10 = 0) None of the networks are considered correct.

  Different power conditions are set depending on the position of the ignition switch key of the vehicle. The supply condition + BAT is reached, either at the cut off contact or at the first position of the key. The supply condition + ACC is reached from the second position of the key. The supply condition + APC is reached from the third position of the key. The supply condition + DEM is reached in the fourth position of the key. 5 In the + DEM feed condition, the consumer elements powered by the + ACC condition are cut off.

  Voltage classes are defined for the networks 7 and 10, with U7-dem-min at U7-dem-max and UI0Odem.min at UI0-dem-max and not at start-up phase, U7.min at U7 -max and UI0omin at U10.max.

  The term "phases" refers to the various operating states of the vehicle described in the following table. Phase Description Engine status Vehicle condition A + BAT, doors closed stopped stopped or rolling A '+ BAT, door (s) open (s) stopped stopped or rolling B + ACC stopped stopped or rolling C + APC, vehicle stopped stopped stopped C '+ APC, rolling freewheel stopped rolling D + DEM, starting with key stopped -> turning stopped or rolling E + APC, starting by start stopped - running stopped F + APC, stop of engine by stop rotating - stopped stopped G + APC, motor autoentra. born, vehicle at stop standing stopped H + APC, self-driven motor, rolling freewheel turning rolling I + APC, rolling gear engaged, no boost and no CR 'rotating rolling J + APC, rolling gear engaged, in revolving boost K + APC, rolling ratio engaged, in CR 'rotating rolling with CR = recuperative load.

  The phases correspond to states where the engine is either stopped or running, except for the transition phases that are the start of the engine, phases D and E and the stopping of the engine phase F. This classification reduces the number of phases and the number of transitions between phases. Some phases or transitions between phases require management tasks by the control unit that are common.

  For the operation of the control unit 5, it is expected that said control unit 5 is awakened by a transition between the phase A and A ', that is to say by the opening of a door of the vehicle.

  From the moment of this awakening, the control unit 5 remains awake in phases A, A 'and B for a determined duration of time delay which can be for example a few tens of seconds. The control unit 5 can be constantly awake during the other phases.

  During a transition from phase C to phase B, the control unit 5 triggers the delay before going to sleep. At the end of the delay, if the phase is A, A 'or B, the control unit 5 goes to sleep, otherwise the control unit 5 remains awake.

  The operation of the transient phase vehicle can be described by the transitions between the phases described above. Transitions in vehicle operation are shown in the table below. On the diagonal of the table, the phase is maintained and off diagonal, a transition is made between two different phases.

  The management strategies of the electrical networks are noted as follows: - Strategy for recharging a battery: r - Support strategy for starting the engine: s 20 - Smoothing strategy at the start of the engine: d - Smoothing strategy at Stopping the operation of the engine: a Non-rotating engine Starting key or Engine running start or stop} AA 'BC CI DEF GH IJKA xr xr xr A' xr xr xr B xr xr xr xr xr C xr xr xr xs x C 'xr xr xr xsxxx D xd xi xs xd E xx xd xd _ = = F xxx ad xa G x xa xxxxx H x xa xxxxx I == x xa = = XXXXXJ lx xa xxxx K x xa xxxx The states of the electrical system 2 are grouped under the term configuration. The possible management configurations are grouped in the table below.

  Config 13 6 12 9 open starter alternator I open direct reverse 19 ri - X -> 0 X <O, = 0,> O 2 = X = 0 <X0,0,> 0 3 - X <- 0 <<O = O> O 4 X> 0 X '<0 x -> 0 - - x <0 6 X <0 - X <0, = 0,> 0 7 X = 0 X> 0 8 X - -> 0 X> 0 9 X> 0 x <0, = 0,> 0 - - X> 0 X <O 11-1 X> 0 x <0 11-2 X <0, = 0 X <O0 Configuration groupings simplify the board. The regulation voltage of the network 10 with respect to the load resting voltage of the network 10 conditions the variants of the summer carried out for the converter 12 on the battery 9 and the configurations 1, 2, 3, 6 and 7. Likewise , the regulator voltage of the alternator-starter 13 on the network 7 with respect to the rest voltage of the battery 6 and the load of the network 7, conditions the variants of the configuration 11.

  The regulation voltages must be defined by the control unit when the alternator-starter is in alternator mode and when the converter 12 is in operation, whether in direct mode or in reverse mode. In configuration 5, the control voltages of the alternator-starter 13 and the converter 12 must be identical because the regulations are made on the same network 7. However, the configuration 5 is not of significant use. Corresponding configurations of the charging cases of either battery by an external charger have not been mentioned in the table.

  defined phase The operation of the network can be summarized by a table according to the configuration related to the context of the batteries above.

  Context 1: Architecture Configuration Phase 1 2 3 4 5 6 7 8 9 10 11 A x A 'x B x C x C' === = x = D xd xh2 xhl E __ xd xh2 xhl

F

  Gxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx In hi, the high voltage battery is undersized and must be supported by the low voltage battery to start the engine. In h2, the high voltage battery is to start the engine alone in normal conditions.

  Context 2 Phase = = Confi tio n architecture Remarks 1 2 3 4 5 6 7 8 9 10 A xb xb A 'xb xb B x_ xb C xb xb C' xb xb D xd E the stop authorization must not allow any result in this occurrence

F

  G xxx H xxx I xxx J _ = = = = the boost is not allowed K x cr == = = = = = = In b, the battery 9 recharges the battery 6. In b, the previous strategy is not more active. The charging strategy of the battery 6 by the battery 9 is not engaged in phase A, but in phase A ', B, C or C'. On the other hand, this strategy can be active during phase A as long as the exit conditions of said strategy are not verified.

  Context 3: Architecture Configuration Phase Remarks 1 2 3 4 5 6 7 8 9 10 11I A x A '= xb_B = _xbC xb xb C' _ xb xb D xd

E

F

  F = __ = __ = _ = __ == = __ = _ = __ = = G x x x H x x x I x x x J = = = _ _ _ _ _ the boost is not allowed K x cr Background 4

I

  Phase Architectural Coniguration Notes 1 2 3 4 5 6 7 8 9 10 11 A x A 'x B x C x C'x D xd xd t_

E F

  G x x x H x x x I x x x J Boost is not allowed K xcr A simplification of the number of phases can be envisaged, particularly with respect to the operating tables above. Phases A and B can be considered identical. They are distinguished by the supply condition (+ BAT and + ACC) of the consumer elements 11 on the network 10, therefore by the current drawn on the battery 9 and the resulting voltage drop on the battery 9 of the voltage safety thresholds network associated with each of these phases can be considered identical.

  Phases D and E correspond to two motor starting phases, respectively by actuation of the starter with the condition + DEM, and by a start. Phases D and E both require voltage smoothing.

  Phases G, H and I can also be considered identical. In these three phases, the engine rotates and neither the boost or over-acceleration, nor the recovery load are implemented. To reduce the oxidation of batteries 6 and 9, it is desirable to

  reduce the charging current of the battery according to its temperature. For this purpose, the control unit 5 comprises a thermal compensation module, generally in the form of a portion of software (possibly in the form of a circuit) adapted to control the converter 12 in this sense. The converter 12 will regulate the network 10 according to a decreasing linear law with the temperature. The thermal compensation module of the control unit 20 implements two thermal compensation laws for the network 7 as a function of the phases. A first law is of linear type decreasing with the temperature: U7 = U7-base + coefficient temperature x (T-20). T is the temperature in degrees centigrade and U7.base is the control voltage for a temperature of 200. This law is used for phases G, H and I. For phase K or the phase of recovery charge, the previous voltage to which a positive voltage AU is added. The phase control voltage K must be slightly greater than the no-load voltage of the battery 6 so as to charge it without drying it out. In particular, if the state of charge does not exceed 80%, the threshold beyond which the electrochemical reaction of the battery releases gas, then the risk of drying up in the battery becomes weaker. The control unit 5 also implements thermal compensation laws during the phases where one of the batteries charges the other battery. Similarly, the recharge voltage of a battery follows a decreasing linear law as a function of temperature.

  The purpose of the RAM-EFF-CAPA flag is to indicate whether, after a start-up phase D, the voltage level of the batteries 6 and 9 must be taken into account as an input or output condition of the charging strategies. one battery by the other. When the control unit 5 wakes up, the RAM.EFF.CAPA flag is 0 by default.

  If the motor does not start from a phase D, then RAMEFF CAPA = 1. The capacitive effect occurs and the flag indicates that network voltages must not be taken into account as a condition of entry and output of the charging strategies of one battery by the other.

  For simplicity, the RAM-EFF-CAPA flag remains at 1 as long as phase C is maintained. Following a transition from phase C to phase B, then a delay delays the shutdown of control unit 5. The RAM-EFF-CAPA flag is set to 0 only after the expiration of the delay time and if the phase is A, A 'or B | If the engine starts, which results in a flag "engine-auto.trained = 1", by the actuation of the starter, transition from phase D to G or H, or by a thrust exerted on the vehicle, transition from phase C 'to 1, J or K, then the RAM-EFF-CAPA flag is set to 0. Indeed, in the case of a key start, the capacitive effect exists only transiently during the duration charging the battery 6 and the battery 10 by the alternator25 starter 13. Under these conditions, the reset of the RAM flag.

  EFF.CAPA can take place as soon as the heat engine is self-driven.

  In the case of a diesel engine equipped with a pre-postheating means to ensure a correct start, preheating is performed on a transition from phase B to phase C or C '. If the engine start, transition from C to D, does not take place before a pre-set time has elapsed, preheating is maintained for an additional time. When starting the engine, post-heating is performed for a pre-set time.

  The strategy of recharging the battery 9 by the battery 6 is intended to allow a start of the engine with support network 10 and to avoid a reset of the control unit 5 for lack of a suitable power supply. However, such a strategy does not allow a real energy recharge of the battery 9. This strategy is operational during phases C or D, especially when using the glow plugs of a non-rotating diesel engine, powered candles by the network 10. This strategy corresponds to the configuration 6 in phases C and D. The control unit 5 comprises a battery charging module 9 by the battery 6, generally in the form of a portion of software or possibly in the form of a circuit adapted to control the converter 12 in this sense.

  The implementation of this strategy is authorized in phases C, C or D, if the state of charge of the battery 9 or the network 10 is judged to be low and if the state of charge of the battery 6 or the network 7 is considered correct (context 3).

  This strategy is stopped if it is implemented for a duration greater than a pre-established duration, if the state of charge of the battery 6 or the network 7 is judged to be incorrect, in case of transition from a phase D towards a phase G or H, that is to say a successful start of the heat engine, and in case of transition from a phase C 'to a phase I, J or K. If the first test of starting the heat engine n has not succeeded, then the capacitive effect occurs and the voltage measurement on the networks 7 and 10 is not significant. The RAM EFF CAPA flag goes to 0. The input and output conditions no longer take into account the voltages U6 and Ug.

  The application of this strategy in phase D is not simply a battery charging strategy 9, but also a network support strategy 10 which makes it possible in particular to preheat a diesel engine. A suitable flag may be provided to prohibit linking two refills of the battery 9 by the battery 6 in phase C. A phase transition B to C may be required to perform the strategy of recharging phase C. The strategy of recharging the battery 6 by the battery 9 is intended to allow a start of the engine. Such a charge makes it possible to slightly increase the no-load voltage of the battery 6 by performing a kind of wakeup of its electrochemical system of the same kind as that which can be effected by a call for headlights prior to starting. The control unit 5 comprises a module for charging the battery 6 with the battery 9, generally in the form of a portion of software or possibly in the form of a circuit capable of controlling the converter 12 for such charging. .

  This strategy is implemented in configuration 8 in phases A, A ', B, C or C', and in configuration 11-1 in phase D. The beginning of the strategy is carried out in phases A, A ', B, C , C 'or D, that is to say engine stopped. The state of charge of the battery 6 or the voltage of the network 7 will have been judged to be low, and the state of charge of the battery 9 or the voltage of the network 10 will have been judged correct. The implementation of this strategy is stopped after a predetermined time, if the state of the network 10 is no longer satisfactory, in case of transition from a phase D to a phase G or H, or a phase C 'to phase 1, J or K. If the first start-up test failed, then the capacitive effect may occur and the voltage measurement on the networks 7 and 10 is no longer significant : RAM-EFF-CAPA = 0. The entry and exit conditions of said strategy no longer take into account the voltage of the networks 7 and 10.

  The occurrence of charging the battery 6 by the battery 9 is limited to twice. The first refill can be performed as soon as the control unit 5 wakes up, for example when a door of the vehicle is opened in phase A '. This makes it possible to recharge the battery 6 by anticipating the start of the engine as soon as possible. The charging can only be carried out once in phases A ', A or B before a rotating thermal engine state. However, a passenger opening a door does not necessarily mean that the engine is started. To reduce this probability of recharging the battery 6 without starting again, a second recharge of the battery 6 can only be performed in phase C. The recharging can also be done only once in phase C before a rotating thermal engine state. These two reloads, whose occurrence can be memorized by flags, can be done in the indicated order or in reverse order.

  The application of this strategy in phase D is not a strategy for charging the battery 6, but rather a strategy for supporting the alternator-starter 13 at the start of the engine. This strategy is implemented according to particular input and output conditions in phase D and is not limited in number of occurrences.

  The strategy of smoothing the starting of the engine which is implemented by the control unit 5 which comprises a module or a circuit for this purpose is intended to avoid a torque surge on the heat engine related to the request. The voltage of the network 10 is ramped up to a final control voltage. The control unit 5 comprises a motor start smoothing module, generally in the form of a software portion or possibly in the form of a circuit capable of controlling the converter 12 for such smoothing.

  The entry conditions in the starting strategy of the heat engine correspond to all the possible transitions between a stationary engine and a running engine: from D to G, from E to G, from F to E, from C to D, from C 'to I, from C' to J, from C 'to K. The exit conditions of this strategy correspond to all possible transitions between a rotating engine and a stopped engine: from or G to C, from I, J or K to C ', from E, G, H, J, J, K to B. At a sudden demand of current from the electrical network, the alternator 13 delivers the current only gradually following a ramp that can be linear, quadratic or other.

  The progressivity of the ramp depends on several factors, in particular the speed of the engine at instant to occur the engagement of an additional charge and the value of the inrush current AI (t) related to the engagement of an additional load, relative to the current I (N) related to the speed of the engine N (t). The rise time Ai of the current ramp is even higher than the N regime is low.

  By way of example, at idle, the rise in current must be very progressive so as not to overload the thermal motor. The rise time At is also higher than the ratio Ai / i (N) is high. When the current draw is carried out at a speed N (t), between the idle speed and the cutoff regime, the duration is interpolated linearly. The battery 9 provides during the rise time of the current Ij3, the current required.

  The smoothing strategy at the cut-off of the heat engine is intended to avoid a significant drop in the benefits provided by the consumer elements 11 of the network 10 when stopping the engine. The control unit 5, which comprises a module or a circuit for this purpose, then regulates the voltage on the network 10 in a ramp until it reaches the idle voltage of the battery 9. The input conditions of this strategy correspond to all possible transitions between a rotating heat engine and a thermal engine at a standstill, namely the phase F and the transitions D or G to C, I, J or K to C 'and E, G , H, 1, J, K to B. The output conditions correspond to all possible transitions between a thermal engine at a standstill and a thermal engine running, that is to say from D or E to G, from F to E, from C 'to D, 1, J or K. Of course, the smoothing strategy at the cut-off of the heat engine requires a standby standby of the control unit 5 during the duration of the smoothing. If the engine is restarted during a shutdown phase or if it is stopped during a start-up phase, then the smoothing ramp is applied at the instant of the change. The purpose of the stop authorization strategy is to determine the conditions on the electrical networks that allow a stop. By "stop" is meant here a stop of the engine for a short duration, for example in a traffic jam or at a red light, followed by a restart. The stop is authorized if the state of charge of the batteries or the voltage of the networks is considered correct: see context 1. Otherwise, the strategy of authorization of stop is inhibited. Associated with phase F, provision is made for configuration 6 and the implementation of a smoothing strategy at the shutdown of the engine. The control unit 4 of the heat engine 3 which includes a stop control module can also emit a stop or stop flag according to the operating conditions of the heat engine. In a complementary way, the "start" request strategy aims at determining the conditions on the electrical networks that impose a "start", later at a stop. A "start" is considered here as an automatic start of the engine, out of action of the driver, following a stop. The start is implemented if the state of charge of the batteries 6 and 9 or if the voltages on the networks 7 and 10 are not satisfactory. The start command emanates from the control unit 5 and can also be requested by the control unit 4 and validated by the control unit 5 which comprises a module for this purpose. In the start phase or phase E, in the context 1, the control unit 5 applies the configuration 10 and allows a smoothing strategy at startup of the engine.

  In context 2, a start request is made. We go to configuration 11 and then 7, then we implement a smoothing strategy at the start of the engine. Then, the stop is prohibited as the voltage on the network 7 remains below a predetermined threshold. In context 3, the start request is made. We go to configuration 9 and implement a smoothing strategy at the start of the engine. Then, the stop is prohibited as the voltage on the network 10 remains below a predetermined threshold voltage. In context 4, in a configuration 10 or 11, the smoothing strategy is implemented at the start of the heat engine.

  The start is requested by the control unit 5 in contexts 2, 3 and 4. If the start did not start the heat engine, then the control unit 4 sends to the control unit 5 a exit order of the stop strategy. The starting of the heat engine 35 must then be performed with the ignition key or equivalent. During this, the converter 12 is in an open circuit waiting for a phase G. The authorization strategy of "boost" or over-acceleration implemented by a boost module of the control unit 5 which determines whether the conditions on the electrical networks that allow a boost are met, and then controls the alternator-starter 13 and the converter 12 in this sense. If the state of charge of the batteries 6 and 9 is correct or if the voltages on the networks 7 and 10 are suitable, the boost is allowed. The boost may be requested by the control unit 4 and enabled by the control unit 5, and has two steps.

  A first step is said torque shedding in which the alternator-starter 13 is in open circuit and the battery 6 provides energy to the network 10 via the converter 12, then a second step in which the alternator-starter 13 operates as a starter and the battery 6 supplies power to the grid 10 via the converter 12. More specifically, the boost may be authorized only if the voltage U6 is greater than a predetermined voltage of authorization of the boost, and the boost can be interrupted if the voltage U6 becomes lower than a minimum boost voltage. The boost takes place in phase J in configurations 1, 2 or 3.

  The converter 12 is kept active to maintain voltage regulation on the network 10.

  The control unit 5 also implements a recuperative charging strategy which aims to prevent corrosion of the battery 6 following the maintenance of a constant voltage across its terminals for a prolonged period. If the vehicle is in the following driving conditions: position + APC - gear engaged - position engaged - engine running at higher idle speed to avoid stalling the engine during the implementation of the strategy - alternator-starter 13 in alternator mode - accelerator pedal released, then the battery 6 recovers energy from the alternator-starter 13.

  The above conditions set a recovery demand flag. The recovery charge 5 is terminated if the key is in the + ACC or + BAT position, during a shift to neutral, during a disengagement, during a stall of the engine, during a stall regime. engine idle, when the vehicle is stopped, when the alternator-starter is in starter mode or in open mode, when the accelerator pedal is depressed.

  At the input of the recuperative charging phase, the control voltage of the alternator-starter 13 follows a ramp for a transient period to reach the maximum regulation voltage from the voltage U6. When the maximum regulation voltage is reached, the current entering the battery 6 is the highest, therefore the resistive torque offered to the heat engine is the strongest.

  At the output of the recuperative charging phase, the regulation voltage of the alternator-starter 13 follows a ramp for a determined transient period to reach the usual regulation voltage. The K phase of the recovery charge will take place under configuration 1.

  The electrical system, according to the invention, is equipped with batteries that can be of various types, including lead, NiMH, lithium, or super-capacity type.

  Thanks to the invention, the electrical system which passes power between the two networks of different voltages is a DC-DC converter based on electronic components whose output voltage can be modulated. The transfer of power from one network to another is therefore particularly easy and flexible. Batteries are solicited in the normal use cases and not only in degraded mode and the voltage on the networks can change depending on the current drawn, the temperature of the batteries, etc. The software implemented in the control unit 5 is simple and economical and provides interesting management in degraded mode. In the event of discharge of one of the batteries, the system can allow the vehicle to start the engine, which will allow it to both roll and supply electricity to the electrical networks by means of the electric generator. for example in the form of a starter alternator.

Claims (12)

  A two-voltage power supply system for a vehicle comprising a first high-voltage network (7) capable of supplying a first group of consumer elements (8), a second low voltage network (10) capable of supplying a second group of consumer elements (11), the first network being connected to a high voltage battery (6), the second network being connected to a low voltage battery (9), and an electronic conversion means (12). ) able to transfer energy from the first network to the second network and from the second network to the first network, characterized in that it comprises a control unit (5) able to control the conversion means as a function of states of the electrical system, said states being grouped under management configurations, each management configuration corresponding to a state condition of an alternator capable of supplying power to the electrical system that, in the sense of the current in each battery and in the conversion means, as a function of operating parameters of a vehicle equipped with said system, according to battery charging criteria, and according to the state of the electrical system criteria .   2-System according to claim 1, characterized in that the battery charge criteria are Boolean values equal to 1 if the state of charge of the corresponding battery is greater than a predetermined threshold.   3-System according to claim 1 or 2, characterized in that the condition criteria of the electrical system are Boolean values equal to 1 if the voltage of the corresponding network is within a predetermined range for a strategy to be implemented.   4-System according to any one of the preceding claims, characterized in that the control unit comprises at least one means for controlling a first energy transfer by the conversion means (12) of the first network to the second network, and a second energy transfer by the conversion means of the second network to the first network.   5-system according to claim 4, characterized in that the software comprises means for controlling a first energy transfer from the first network to the second network when a recharge of the low voltage battery is required.   6-System according to claim 4 or 5, characterized in that the software comprises means for controlling a second energy transfer from the second network to the first network when charging the high voltage battery is necessary or when a high power is requested on the first network.   7-System according to any one of claims 4 to 6, characterized in that the software comprises a means for smoothing the transitions between modes of operation.   8-System according to any one of claims 4 to 7, characterized in that the software comprises means for taking into account the temperature of a battery when recharging said battery. System according to any one of the preceding claims, characterized in that the first network is powered by an alternator and supplies a starter.   10-Method for power supply with two voltages for a vehicle, from a first high voltage network (7) able to power a first group of consumer elements (8), a second network (10) with voltage the first network being connected to a high voltage battery (6), the second network being connected to a battery (9) with a low voltage, and a second one being connected to a battery (6) with a high voltage; electronic conversion means (12) adapted to transfer energy from the first network to the second network and from the second network to the first network, wherein the conversion means is controlled according to states of the electrical system, said states being grouped under management configurations, each management configuration corresponding to a state condition of an alternator capable of supplying power to the electrical system, in the sense of the current in each battery and in the yen of conversion, according to operating parameters of a vehicle equipped with said system, according to the criteria of charging of the batteries, and according to the state of the electrical system criteria.   The method of claim 10, wherein the low voltage battery (9) is recharged by the high voltage battery (6) to allow the engine to start and to prevent a reset of a control unit, if the charge criterion of the low voltage battery is not satisfied, or if the condition criterion of the low voltage network is not satisfied, and if the condition criterion of the high voltage network is satisfied, and if the criterion of high voltage battery charge 10 is not satisfied.   12-A method according to claim 10 or 11, wherein the high voltage battery (6) is recharged by the low voltage battery (9) to increase the voltage of the high voltage battery (6), if the charging criterion the high voltage battery is not satisfied, or if the condition criterion of the high voltage network is not satisfied, and if the condition criterion of the low voltage network is satisfied, and if the criterion Low voltage battery charge is satisfied ,.   13-Process according to any one of claims 10 to 12, wherein the engine is assisted by means of the alternator if the load criterion of the high voltage battery is satisfied, and if the criterion of state of the high voltage network is satisfied.   14-Process according to any one of claims 10 to 13, wherein one recharges at least one battery by recovering energy on the engine through the alternator25 starter (13) if a gear is engaged, in the engaged position, if the engine is running at higher revs than idle, if the alternator starter is in alternator mode, and the accelerator pedal is released. 15-Process according to any one of claims 10 to 14, wherein the engine is stopped for a short time if the state of charge of the batteries or the condition criteria of the electrical system are considered correct, then it is restarts if the state of charge of the batteries or if the condition criteria of the electrical system are not satisfactory. 16- A method according to any one of claims 10 to 15, wherein if a first test start of the engine has failed, then the voltage measurement on the networks (7, 10) is not significant and the condition criteria of the electrical system are no longer taken into account.