FR3003827A1 - ELECTRICAL POWER SUPPLY SYSTEM OF A HYBRID MOTOR VEHICLE ON-BOARD NETWORK - Google Patents

Abstract

The onboard network (8) comprising a starter (85) and at least one vehicle equipment (80-84), the power system comprises a power battery (1) having N modules in series (1 0a-1 0f ), able to supply the on-board network (8) via N respective voltage converters (2a-2f). The N converters (2a-2f) are distributed in a first (2a, 2b) and a second group (2c-2f), each group comprising between 1 and N-1 converters. The first group is connected to a first power output (4), intended to power said equipment (80-84), and the second group is connected to a second power supply (5), electrically separated from the first ( 4) for supplying the starter (85).

Description

FIELD OF THE INVENTION The invention relates to a system for supplying a hybrid motor vehicle onboard network. With a hybrid vehicle, comprising a heat engine and an electric motor, it may be necessary to start the engine while driving, during a purely electric propulsion phase. For this purpose, the on-board vehicle network may comprise an alternator-starter. During the start-up phase of the starter-alternator, the voltage of the vehicle's on-board network, generally a low voltage of 14V, falls due to a large current draw by the alternator-starter. Such a voltage drop is likely to cause a stop followed by a restart of network equipment. Some of these devices provide safe functions such as brake assist. It is essential, for safety reasons, to avoid even a temporary shutdown of these equipment during a driving phase. The present invention improves the situation. To this end, the invention relates to a power supply system for a hybrid motor vehicle network, said network comprising a starter and at least one vehicle equipment, comprising a power battery comprising N modules in series, capable of supplying the on-board network via N respective voltage converters, characterized in that the N converters are distributed in a first and a second group, each group comprising between 1 and N-1 converters, the first group is connected to a first power supply, intended to power said equipment, and the second group is connected to a second power output, electrically separated from the first, for supplying the starter. Such a power system provides two separate power supplies to the onboard network. Thanks to this, the voltage drop caused by the starting of the electric starter will have an impact only on the elements of the on-board network connected to the second power output, to which the starter is connected. Advantageously, the first power output is intended to power a secure equipment.

The first power output is preferably dedicated to network security equipment, that is to say, equipment whose even temporary shutdown while driving represents a risk in terms of security. Thus, these safety devices are not likely to be impacted by starting the starter.

Advantageously, it comprises at least one auxiliary supply battery connected to one of the power outputs. In a variant, it comprises two auxiliary supply batteries connected to the two respective supply outlets. The auxiliary battery (s) are intended to be charged by the battery modules, in order to feed the on-board network in real time or later. In a particular embodiment, the first group comprises two converters and the second group comprises the N-2 other converters. Two of the N battery modules and associated converters are thus used to supply the equipment or the equipment of the on-board network via the first output. This is enough to power this equipment or these and provides a safe redundancy, in case of failure of one of the two battery modules. Advantageously, it comprises active balancing means integrating said converters, adapted to control a transfer of electrical energy from at least one module to the associated power output so as to balance the respective load levels of the different modules. Active balancing allows energy to be transferred to the power outputs from the more charged battery module (s) to power the onboard network. Advantageously, each converter, associated with a module, is connected to the corresponding power output via a diode capable of interrupting the link between said associated module and said corresponding power output in the event of failure of said module . Thanks to this, in the event of failure of one of the battery modules, in particular in the event of a short circuit, this module is disconnected from the associated power output 5 by blocking the protection diode. The invention also relates to a hybrid motor vehicle onboard network comprising a starter, at least one equipment and a power supply system according to one of the preceding claims, the equipment being connected to the first power supply and the starter being connected to the second 113 power output. Advantageously: - said equipment connected to the first output is a secure equipment; the on-board network comprises at least one unsafe equipment connected to the second power output; the on-board network comprises several security equipment and in that all the security equipment is connected to the first power output; the on-board network comprises several unsafe equipment connected to the second power output; the starter is an alternator-starter; The invention also relates to a motor vehicle incorporating a feed system as defined above or an edge network as defined above. The invention will be better understood with the aid of the following description of various embodiments of the power supply system and the hybrid vehicle edge network according to the invention, with reference to the appended drawings in which: FIG. 1 schematically shows the power system 30 of the on-board network, according to a first embodiment; FIG. 2 diagrammatically represents the on-board network powered by the power supply system of FIG. 1, and FIG. 3 represents a flowchart of the steps of a method of supplying the on-board power system with the aid of the system. In Figure 1, there is shown a power system of an onboard network of a hybrid motor vehicle comprising a heat engine and an electric motor. The onboard network 8, shown in FIG. 2, is a low-voltage network, in this case 14 V. It comprises comfort equipment, such as a radio 80, an air-conditioning system 81, window motors 82, etc., and driving equipment, such as a brake assist computer 83 and a wheel lock anti-lock computer 84, etc.). Some equipment, known as "safe", provide safety functions while driving (brake assist 83, anti-lock wheel 84). Other equipment, called "unsafe", provide functions having little or no impact on safety during driving (air conditioning 81, radio 80, closing / opening windows 15, etc.). The onboard network 8 further comprises a starter 85 adapted to provide a starting function of the engine. In the embodiment described here, the starter 85 is an alternator-starter, able to start the engine, especially during a purely electric driving or propulsion phase, that is to say while the vehicle is already driving. using the electric motor. The power system comprises a traction battery 1, or power, high voltage, for example 400V. The traction battery 1 is here an electrochemical accumulator battery. It comprises a plurality N 25 of accumulator modules placed in series. In the particular example described here, the battery comprises six accumulator modules (in other words N = 6), denoted 10a to 10f. Each accumulator module 10a-10f incorporates one or more accumulator stages, these stages being put in series. Each accumulator stage (s) may comprise one or more accumulators 30 in parallel. The N battery modules 10a-10f are respectively connected to N voltage converters 2a to 2f. Each converter 2a-2f has two input terminals connected to the terminals of the corresponding battery module 10a-10f. The supply system comprises two separate supply outlets, denoted 4 and 5. The first supply output 4 is intended to supply certain equipment, here comprising at least the safe equipment of the on-board network 8, namely the computers 83 and 84. The second power output 5 is intended to power at least the starter 85. The unsecured equipment (80, 81, 82) of the onboard network 8 are here connected to the second output 5. However, it would be possible to consider connecting one or more unsecured equipment to the first power output 4. Preferably, all the security equipment of the on-board network are connected to the first output 4. In the particular example described here, two converters 2a and 2b are connected at the output to the first power output 4, and the other four converters 2c-2f are connected at the output to the second power output 5. The utilization n at least two battery modules and two associated converters for each power output 4 (5) provides safe redundancy especially in case of failure of one of the two battery modules. In addition, for the power supply of the computers 83, 84, the use of two battery modules is sufficient. Each converter 2a-2f provides galvanic isolation between the battery module 10a-10f and the power output 4 or 5, to which it is connected. A protection diode 3a-3f is interposed between each converter 2a-2f and the corresponding power supply output 4 or 5. This diode 3a-3f is adapted to switch from an on state to a off state in the event of a failure. battery module to which it is connected, especially in case of short circuit. When a diode 3a-3f is blocked, the corresponding module 10a-10f is no longer connected to the corresponding power output. The power system also includes two auxiliary batteries 6 and 7 respectively connected between the power outputs 4 and 5 and the ground. These two auxiliary batteries 6, 7 are intended to be charged by the battery 1, as will be described later, and supply the edge network 8. However, these auxiliary batteries 6, 7 are optional. One or both of them could be deleted. The edge network 8 is thus divided into two parts, supplied separately: a first portion 8A comprising the security equipment 83, 84; a second part 8B comprising the starter 85 and here the unsafe equipment 80-82. These two parts 8A and 8B are fed by two power inputs electrically separated from each other. Thanks to this, a voltage drop caused by a starting alternator-starter 85 will only impact the second part 8B of the onboard network 8 and have no impact on the security equipment of the first part 8A of the onboard network. 8. The converters 2a-2f belong to an active balancing system intended to feed the on-board network by balancing the charges of the modules 10a-10f of the battery 1. In the particular example described here, the active balancing system operates in a similar way to the principle of active balancing zo described in the document FR2959885, with the difference that the balancing serves to balance the load levels between the different modules, as explained below. Active balancing consists of transferring energy from the most charged battery module (s) to the on-board network 8 via the converters 2a-2f, until all the modules 10a-10f of the battery 1 reach an average load threshold, and so as to supply the on-board network 8. The balancing system comprises - converters 2a to 2f, for example flyback converters, - 9a-9f monitoring devices able to monitor the respective load states of the battery modules la-1f and a control device 11 adapted to control the converters 2a to 2f so as to balance the load of the modules 1a-1f.

The state of charge of a module la-1f can be monitored by a measurement of the voltage at the terminals of this module, this voltage being indicative of the state of charge of the module. In this case, the state of charge of each battery module 10a (10b-10f) is monitored by a tensiometer 9a (9b-9f) connected to the terminals of the module. An example of operation of the on-board power supply system 8 will now be described with reference to FIG. 3. In a first step E1, the voltage at the terminals of each battery module 10a-10f is measured at means of the corresponding monitoring apparatus 10a-9f. During a step E2, the control device 11 compares the measured voltages across the various modules 10a-10f during a step E3. If at least one of the modules is more loaded than the other modules, in a step E4 (branch Y in FIG. 3), under the control of the control device 11, the respective loads of the modules are balanced by transferring the energy of the most heavily loaded module (or the most charged modules in the case where several modules are more loaded than the others), to the corresponding auxiliary battery (ie to the battery 6 for the modules 10a and 10b and to the Battery 7 for the modules 10c-10f), via the corresponding converters, similarly to the balancing method described in the document FR2959885. When the charges of the different modules are balanced, the process returns to step E1. If the charge states of the different modules are equal (branch N in FIG. 3), the process returns to step E1. In all cases the method (steps E1 and following) is reiterated at regular time intervals in order to regularly monitor the respective charge states of the modules. As a variant, the control device 11 could compare the measured voltages of the various modules 1a-1f with a threshold voltage, deduce a relative load ratio and control, for each module, a possible transfer of energy in FIG. function of this relative load ratio, as described in document FR2959885. For more details on the different variants of realization of the active balancing, the reader is invited to refer to the document FR2959885. In any case, the balancing is carried out by first discharging the most charged modules via their associated converter to supply the part of the corresponding edge network 8 (8A or 8B). Energy transfer by active balancing can be done at any time of the operation of the vehicle.

The transferred energies are used to charge the auxiliary batteries 6 and / or 7. In the absence of an auxiliary battery, these energies provided by balancing would serve to feed directly and in real time the associated network portion 8A or 8B. When the starter-alternator 85 is put into operation in starter mode, in particular during a purely electric propulsion phase, a voltage drop occurs in the part 8B of the on-board network 8. On the other hand, no voltage drop occurs in part 8A of the on-board network 8. The safety equipment of the on-board electrical system, located in the part 8A of the on-board system, therefore do not risk being impacted by the voltage drop.

In the foregoing description, the active balancing means incorporating the converters are adapted to control a transfer of electrical energy from one or more battery modules to the corresponding power output (i.e. ie that associated with the module considered) so as to balance the respective load levels of the different modules.

Alternatively, one could consider active balancing means incorporating converters, adapted to control a transfer of electrical energy from one or more stage (s) of accumulators to the corresponding power output so as to balance the levels charge levels of the accumulator stages of the same module.

Claims (10)

REVENDICATIONS1. Hybrid motor vehicle network (8) power supply system, said network (8) comprising a starter (85) and at least one vehicle equipment (80-84), comprising a power battery (1) ) comprising N series modules (10a-10f), able to supply the on-board network (8) via N respective voltage converters (2a-2f), characterized in that the N converters (2a-2f) are distributed in a first (2a, 2b) and a second group (2c-2f), each group comprising between 1 and N-1 converters, the first group is connected to a first power output (4), intended to supply said equipment (80-84), and the second group is connected to a second power output (5), electrically separated from the first (4), for supplying the starter (85). 2. System according to claim 1, characterized in that the first supply outlet (4) is intended to supply a secure equipment (83, 84). 3. System according to the preceding claim, characterized in that it comprises at least one auxiliary supply battery (6, 7) connected to one of the power supply outputs (4, 5). 4. System according to claim 2, characterized in that it comprises two auxiliary supply batteries (6, 7) connected to the two respective supply outlets (4, 5). 5. System according to any one of the preceding claims, characterized in that the first group comprises two converters (2a, 2b) and the second group comprises the N-2 other converters (2c-2f). 6. System according to any one of claims 1 to 5, characterized in that it comprises active balancing means incorporating said converters (2a-2f), adapted to control a transfer of electrical energy from at least one module (10a-10f) to the associated power output (4, 5) so as to balance the respective load levels of the different modules (10a-10f). 7. System according to one of the preceding claims, characterized in that each converter (2a-2f), associated with a module (10a-10f), is connected to the corresponding power output (4, 5) by the intermediate of a diode adapted to interrupt the connection between said associated module (10a-10f) and said corresponding supply output (4, 5) in the event of failure of said module (10a-10f). 8. Dashboard (8) of a hybrid motor vehicle comprising a starter (85), at least one equipment (80-84) and a power supply system according to one of the preceding claims, the equipment (80-84) being connected to the first power output (4) and the starter (85) being connected to the second power output (5). 9. Dashboard according to claim 8, characterized in that said equipment connected to the first output (4) is a safety equipment (83, 84). 10. Dashboard according to claim 8 or 9, characterized in that it comprises at least one unsafe equipment (80-82) connected to the second power output (5).