FR2878088A1 - Electrical power supply system for e.g. dual voltage electrical system of motor vehicle, has safety system whose supply is reinforced, in case of voltage drop of one sub-system, by another sub-system using voltage converter - Google Patents

Abstract

The system (10) has sub-systems (12, 14), and a safety system (Rp) to which components sensitive to low voltages are connected. The system (Rp) is supplied by the sub-system (12) connected to the system (Rp) by a diode (D). The supply of the system (Rp) is reinforced, in case of voltage drop of the sub-system (12), by the sub-system (14) using a voltage converter (22) connected between the sub-system (14) and the system (Rp).

Description

] L

  The invention relates to multi-voltage electrical networks fitted to motor vehicles and relates, more particularly, to a system for supplying electrical energy to a vehicle. such a network. More particularly, the invention relates to bi-voltage electrical networks of motor vehicles.

  In order to meet the increasing demand for electrical power in vehicles, linked to the appearance of new high-power electrical functions, various solutions have been envisaged.

  One of the advantageous solutions is to increase the voltage available on the network by increasing the output voltage of the alternator. This solution allows, in particular, the use of new components whose nominal voltage is increased. However, the increase of the output voltage of the alternator must remain compatible with the current standards of the voltage of the on-board network, for example 12 volts, because it is not possible to replace brutally and completely conventional networks by a higher voltage network, for industrial, technical and economic reasons. It is therefore necessary to envisage a phase of coexistence of two sub-networks of power supply within the same vehicle, even if it is necessary to foresee the future evolution of certain consumer circuits of the conventional voltage sub-network towards the subnet of increased voltage.

  In the state of the art, there are known power generation systems for two-voltage networks of a motor vehicle. Such systems include, for example, a three-phase alternator whose stator phases are rectified to generate a power on a sub-network operating at a first voltage value and whose stator is wound in a star so as to present a neutral point to which is connected a second subnet operating at a second voltage value lower than the first voltage.

  In this regard, reference may be made to the European patent application EP-A-1 112 896 in the name of the applicant.

  But in this type of power system, the subnets are structurally and functionally independent.

  In view of the foregoing, the object of the invention is to enable the supply of a two-voltage electrical network of a motor vehicle and, moreover, to provide a balancing of the energies produced on each of the sub-networks.

  The subject of the invention is therefore a system for supplying electrical energy to a two-voltage on-board electrical network of a motor vehicle, comprising at least two sub-networks providing different voltage levels to electrical loads connected to the vehicle. network, the system comprising an alternator-type electric machine associated with a power converter delivering sub-networks electrical energy at said voltage levels under the control of a power management system.

  This system further comprises means for causing the supply of charges connected to at least one sub-network from the energy available on one or more other sub-networks as a function of the supply available on said at least one sub-network. -network.

  According to another characteristic of the invention, the system comprises two power subnetworks, a DC / DC voltage converter controlled by the power management system being connected between the first subnet and the second subnet.

  According to one embodiment, the electrical charges comprise first and second groups of charges supplied respectively from the first and second sub-networks, and a third group of charges selectively powered from the first sub-network or the first and second sub-networks. -Networks based on the power available on the first subnet.

  For example, the third group of loads can be connected to a network connected to the first network by a non-return diode and to the second network by said DC / DC voltage converter.

  In a particular embodiment, the first and second sub-networks are each provided with a switch controlled by the management system for the selective connection of the first and second sub-networks to the electrical machine and to the power converter.

  For example, the first subnet is a 12-volt power grid and the second subnet is a 24-volt power network.

  According to another embodiment, the system comprises two ground-to-ground sub-networks, the electrical loads comprising a first group of loads fed from a first voltage level delivered by the first sub-network, a second a group of charges supplied from a second voltage level delivered by the second sub-network, a third group of charges fed from a third voltage level delivered jointly by the first and second sub-networks, and a fourth a group of charges selectively powered from one of the first and second subnetworks.

  For example, the first voltage level is equal to 12 volts, the second voltage level is -12 volts and the third voltage level is +24 volts.

  In the various embodiments mentioned above, each subnet is provided with a power supply battery whose load is ensured by said electrical machine and the DC / DC voltage converter, under the control of the power management system. .

  For example, the electric machine is an alternator or an alternator.

  Other objects, features and advantages of the invention will become apparent on reading the following description, given solely by way of non-limiting example, and with reference to the appended drawings, in which: FIG. 1 is a block diagram of FIG. a system for supplying electrical energy to a bi-voltage electrical network for a motor vehicle according to a first embodiment; and FIG. 2 is a block diagram of a system for supplying electrical energy to a two-voltage electrical network according to another embodiment of the invention.

  Firstly, with reference to FIG. 1, a first exemplary embodiment of a supply system in accordance with the invention designated by the general reference numeral 10 will be described.

  This system is intended to supply a motor vehicle dual voltage on-board electrical network which comprises a first sub-network 12 delivering a first voltage level U1 and a second sub-network 14 delivering a second voltage level U2.

  For example, the first subnet 12 provides a voltage level of 12 volts, and the second subnet 14 delivers a voltage of 24 volts.

  The voltage available on the first and second sub-networks 12, 14 is provided by an alternator-type electrical machine 16, for example a conventional alternator or alternator-starter, and by a power converter 18 associated with the machine 16 and driven by a power management system 20 which communicates with the vehicle control system 21. Electromechanical or electronic switches R1 and R2 controlled by the management system 20 selectively connect the power converter 18 to the first sub-network 12, or the second sub-network 14 or to the first and second sub-networks 12 and 14 simultaneously.

  As can be seen in FIG. 1, each of the sub-networks is provided with a supply battery B1 and B2 each associated with means A1 and A2 for measuring the charge current of the batteries. Complementary current measuring means A3 measure the current flowing on the supply network. The current measurement values il, i2 and 1T delivered by the first, second and third current measuring means A1, A2 and A3 are supplied to the power management system 20. Similarly, the voltages U1 and U2 available to the terminals of the power supply batteries B1 and B2 are delivered to the power management system 20. Finally, the temperatures T1 and T2 of the batteries B1 and B2 are also delivered to the management system 20.

  As indicated above, the first subnet 12 provides, for example, a voltage level of 12 volts, while the second subnet 14 delivers a voltage level of 24 volts. Thus, a first group of vehicle components is powered by this first sub-network 12 while a second group of components is powered by the second sub-network 14.

  As seen in Figure 1, the power supply system 10 also provides a protected network Rp to which are connected components sensitive to brownouts. This protected network is fed from the first sub-network 12 to which it is connected via a non-return diode D. However, in the event of a voltage drop on this sub-network 12, its power supply is increased to from the second subnet via a converter or voltage regulator 22 connected between the second sub-network 14 and the protected network Rp.

  The components of the power supply system 10, in particular the switches R1 and R2, the DC / DC converter 20 and the power converter 18, are controlled by the power supply system 20.

  For example, these components are made from switches, for example transistors of the MOSFET, IGBT, bipolar or other type. Thus, the management system 20 incorporates electronic control and regulation means which, from the voltage measurement signals U1, U2, temperature T1, T2 and current il, i2, iT, and from instructions of regulation establish electronic strategies for managing the electrical energy of the network. Various management strategies, within the reach of a person skilled in the art, can be envisaged for this purpose. For example, pulse width modulation regulation of the switch control signals can be used for this purpose.

  As it is conceivable, thanks to this arrangement, it is possible to benefit from the advantages associated with increasing the edge voltage of a motor vehicle, in particular the increase in power or the use of components of the 24-volt type. , without calling into question the use of conventional devices of the 12-volt type, insofar as the system 10 provides a two-voltage network. In addition, thanks to the presence of the protected network Rp which, in case of voltage drop of the first sub-network 12, sees its enhanced power supply from the second sub-network 14, it is possible to provide a secure supply of sensitive components at brownouts.

  For example, the power supply system 10 according to the invention makes it possible to implement distinct phases of power supply. For example, in the case where a start-up system comprising a 24-volt starter-alternator is used, during a start-up phase, the management system 20 causes the switch R2 to close and the opening of the switch R1 for the power supply of the alternator-starter.

  After starting, the electric power generation phases in which a supply voltage of 12 volts or 24 volts is provided can be implemented depending on the position of the switches RI and R2.

  During this phase, based on current, voltage, and temperature information of the batteries, the power management system 20 maintains a correct state of charge of the two batteries B1 and B2, thanks to switching the switches R1 and R2 and controlling the electric machine 16 to allow the charging of the batteries either 12 volts or 24 volts, depending on their state of charge.

  Another embodiment of a supply system according to the invention will now be described with reference to FIG.

  In this figure, elements identical to those of Figure 1 bear the same reference numerals.

  As in the embodiment described above, this system 10 also comprises an electric machine 16 of the alternator or alternator-starter type associated with a power converter 18 connected to the onboard network of the vehicle.

  The power network also has several power subnets that can be used to power multiple component groups. For example, in the exemplary embodiment shown, this system 10 supplies a first group G1 of components from a supply voltage of + 12 volts, a second group of components G2 from a voltage 12 volt supply, a third group G3 of components from a supply voltage of 24 volts, and a fourth group of components G4 selectively powered via a switch 24 is from a supply voltage of + 12 volts, or from a supply voltage of 12 volts.

  Two 12 volt, preferably identical, power supply batteries B1 and B2 supply the sub-networks together with the electric machine 16 and the power converter 18.

  As seen in this FIG. 2, the power supply system 10 thus comprises, as in the embodiment described with reference to FIG. 1, two sub-networks 12 and 14 respectively incorporating the first battery B1 and the second battery. B2. The first network 12 provides, in the example shown, a voltage level of 12 volts, for the supply of the second group of components, while the second subnet 14 delivers a supply voltage of + 12 volts for the supply of the first group of components. As regards the third group of components, these components are connected between the two sub-networks 12 and 14 so as to be supplied with a voltage of 24 volts. The fourth component group G4 is supplied with either the first subnet 12 or the second subnet 14.

  Indeed, the two sub-networks 12 and 14 have a node common to the ground constituted respectively by the positive terminal of the first battery B1 and the negative terminal of the second battery B2, the negative terminal of the first battery B1 delivering the voltage supply 12 volts and the positive terminal of the second battery B2 providing the supply voltage of + 12 volts. The first group of components is powered from the positive terminal of the second battery B2, the second group of components is powered from the negative terminal of the first battery B1, the third group of components is connected between the positive terminal of the second battery. the second battery B2 and the negative terminal of the first battery B1, and the fourth group of components is selectively connected, by means of the switch 24, to the positive terminal of the second battery B2, or to the negative terminal of the first battery B1.

  As in the architecture of FIG. 1, a DC / DC voltage converter 26 ensures, in the event of a voltage drop on one of the sub-networks, a transfer of energy towards this network from the other sub-network. -network.

  Finally, a power management system 20 drives the power converter 18, a DC / DC converter 26 interposed between the two sub-networks of +12 volts and -12 volts and the switch 24 to manage the level of the voltages available on them. two sub-networks 12 and 14, in particular by contributing to the supply of the sub-network the most requested from the least loaded sub-network, and manages the state of charge of the two batteries by driving the electric machine 16 to maintain a correct charge level of the batteries and by controlling the switch 24 to connect the fourth group of components G4 to either the first subnet 12 or the second subnet 14.

  Finally, it will be noted that the invention generally applies to a multi-voltage on-board network in which several sub-networks provide respective voltage levels and in which, in the event of power loss on one or more sub-networks. , the energy available on one or more other sub-networks is used to reinforce the supply of the deficient sub-network (s).

Claims (10)

  A system for supplying electrical power to an on-board electrical network of a motor vehicle, comprising at least two sub-networks (12, 14) providing different voltage levels to electrical loads connected to the network, the system comprising an alternator-type electrical machine (16) associated with a power converter (18) supplying the sub-networks (12,14), under the control of a power management system (20), electrical energy at said levels voltage device, characterized in that it comprises means (D, 22, Rp, 26) for causing the supply of charges connected to at least one sub-network from the energy available on one or more other sub-networks. networks according to the power supply available on said at least one subnet (12).   2. System according to claim 1, characterized in that it comprises two supply sub-networks (12, 14), and in that a DC / DC voltage converter (22; 26) driven by the control system. power management (20) is connected between the first subnet (12) and the second subnet (14).   3. System according to claim 2, characterized in that the electrical charges comprise first and second groups of charges respectively fed from the first and second sub-networks (12, 14) and a third group of charges selectively powered from the first subnet or first and second subnets depending on the power available on the first subnet.   4. System according to claim 3, characterized in that the third group of loads is connected to a network connected to the first network by a non-return diode (D) and to the second network by said DC / DC voltage converter (22). .   5. System according to any one of claims 1 to 4, characterized in that the first and second sub-networks are each provided with a switch (R1, R2) controlled by the management system (20) for the selective connection first and second sub-networks to the electric machine (16) and the power converter (18).   6. System according to any one of claims 1 to 5, characterized in that the first sub-network is a 12-volt supply network and the second sub-network is a 24-volt supply network.   7. System according to one of claims 1 and 2, characterized in that it comprises two midpoint sub-networks to ground, and in that the electrical charges comprise a first group (G1) of charges fed from of a first voltage level delivered by the first sub-network (12), a second group (G2) of charges fed from a second voltage level delivered by the second sub-network (14), a third group of charges (G3) fed from a third voltage level delivered jointly by the first and second sub-networks (12,14), and a fourth charge group (G4) selectively powered from one of the first and second subnets.   8. System according to claim 7, characterized in that the first voltage level is equal to + 12 volts, the second voltage level is equal to -12 volts and the third voltage level is equal to 24 volts.   9. System according to any one of claims 1 to 8, characterized in that each sub-network is provided with a supply battery whose load is provided by said electrical machine and the voltage switch DC! DC under the control of the power management system (20).   10. System according to any one of claims 1 to 9, characterized in that the electric machine is an alternator or an alternator-starter.