Power supply system

Abstract

The invention relates to a power supply system for electrical equipment, which comprises: A DC power bus, A first battery (BATT1) and a second battery (BATT2) connected in parallel and each capable of supplying a first DC voltage on said DC power bus, An auxiliary battery (B_AUX) configured to supply a second DC voltage (U_AUX), A control unit (CU) configured to: Select at least one battery from the first battery and the second battery to fix said voltage on the DC power bus by connecting it to the DC power bus, Control a connection to the DC power bus of the unselected battery, and a charge of said auxiliary battery (B_AUX) by placing it in series with the unselected battery and switching the cells of said unselected battery to drive a charging current (I_aux) of said auxiliary battery.Figure to be published with the abbreviation: Figure 1.

Description

Title of the invention: Electrical power supply system Technical field of the invention

[0001] The present invention relates to an improved electrical power supply system, which can in particular be used in an electric or hybrid vehicle. State of the art

[0002] The traction of an electric or hybrid vehicle is made possible by the use of several electrical energy storage batteries, gathered in a battery pack.

[0003] In a known manner, a battery pack provides a direct voltage that a DC / AC converter is responsible for converting to provide control voltages to the electric motor of the vehicle on its two or three phases (depending on the configuration of the motor). The battery pack may comprise several batteries, each battery itself comprising several modules and each module generally comprising several electrochemical cells. The system may be reversible and mechanical braking of the motor may also allow the batteries of the battery pack to be recharged, in energy regeneration mode.

[0004] Furthermore, it is known that to power the vehicle's on-board network, i.e. for example the headlights, windows, ABS braking, steering assistance, but also much more basic functions such as centralized opening / closing by remote control, a standard 12V (or 24V) lead battery is often used. The presence of this additional lead battery is justified by the need to have a voltage of 12V even when the vehicle is not switched on and by the need to have an independent 12V source that does not discharge the traction battery. This auxiliary battery is charged by the vehicle's battery pack in the case of an electric or hybrid vehicle, through a DC / DC converter, or by an alternator in the case of a thermal vehicle.

[0005] In non-automotive applications, an additional battery may also be required for system startup.

[0006] For reasons of weight saving, size and cost, it is desirable to avoid the use of this DC / DC converter (or the alternator in the case of a thermal vehicle). In this situation, it is still necessary to have a simple solution for charging the auxiliary battery, whatever the architecture of the system and its operating mode, i.e. normal power supply mode, braking mode (with regeneration) or charge or discharge mode on the AC network.

[0007] The installation of the auxiliary battery must in particular be able to adapt to an architecture capable of permanently supplying a constant direct voltage, for example example of 48V DC or 400V DC in an electric vehicle, through a continuous power bus.

[0008] The aim of the invention is therefore to propose an electrical power supply system which:

[0009] - Is capable of supplying a continuous voltage at a substantially constant level permanently (within 5V), when the vehicle is in operation; - Integrates an auxiliary battery into its architecture and allows it to be recharged without the use of a converter; - May be able to recharge on an external AC network while maintaining the supply of DC voltage (low or high voltage); - May be able to supply AC voltage while maintaining the supply of DC voltage; - Avoids the use of electrical converters as much as possible;

[0010] This system will be particularly suitable for use in an electric or hybrid vehicle to contribute to the vehicle's traction but also to power various pieces of vehicle equipment. Statement of the invention

[0011] This aim is achieved by a system for supplying electricity to electrical equipment, which comprises:

[0012] - A continuous power supply bus, - A first battery capable of providing a first direct voltage on said direct power supply bus, said first battery comprising first switchable cells, An auxiliary battery configured to provide a second direct voltage, separate from the first direct voltage, A control unit, A second battery capable of supplying said first DC voltage on said DC power supply bus, said second battery being connected in parallel with said first battery, said second battery comprising second switchable cells, First switching means arranged to connect or disconnect the first battery from the DC power bus, Second switching means arranged to connect or disconnect the second battery from the DC power bus, Third switching means configured to connect or disconnect the auxiliary battery in series with the first battery and / or in series with the second battery, - Said control unit being configured to: • Select at least one battery from the first battery and the second battery to fix said voltage on the DC power bus by connecting it to the DC power bus, • Control a connection to the DC power bus of the unselected battery, and a charge of said auxiliary battery by placing it in series with the unselected battery and switching the cells of said unselected battery to control a charging current of said auxiliary battery.

[0013] According to a particular feature, the first switching means are arranged to connect or disconnect the first battery to a charging / discharging unit intended to be connected to an alternating network.

[0014] According to another feature, the second switching means are arranged to connect or disconnect the second battery to said charging / discharging unit.

[0015] According to another feature, the control unit is configured to control a charge of the non-selected battery by a connection on said charge / discharge unit.

[0016] According to another feature, the control unit is configured to control the supply of a variable voltage to said charging / discharging unit by connecting the first battery or the second battery to said charging / discharging unit.

[0017] According to another feature, the control unit is configured to control a connection of the auxiliary battery in series with both the first battery and the second battery to charge the auxiliary battery using a current present on the DC power bus.

[0018] According to another feature, the control unit comprises means for monitoring the following quantities:

[0019] • The voltage across the terminals of the first battery, • The voltage at the terminals of the second battery, • The voltage at the terminals of the auxiliary battery, • The current which flows in a first branch carrying the first battery, • The current flowing in the second branch carrying the second battery, • The charging current of the auxiliary battery. • The DC power supply bus voltage;

[0020] According to another feature, the control unit comprises means for determining and monitoring the state of charge of the first battery, the state of charge of the second battery and the state of charge of the auxiliary battery, from the values ​​of the monitored quantities.

[0021] According to another feature, the control unit comprises control means of the charging current of the auxiliary battery by applying connection phases and disconnection phases of the auxiliary battery to said non-selected battery.

[0022] According to another feature, the first battery and the second battery each comprise several cells connected in series and parallel, each cell comprising at least one capacitor and switching means.

[0023] The invention also relates to a control method implemented in the control unit of an electrical power supply system as defined above, said method comprising the following steps:

[0024] - Selecting at least one battery from the first battery or the second battery to supply said voltage on the DC power bus by connecting it to the DC power bus, - Control a connection to the DC power bus of the unselected battery, and a charge of said auxiliary battery by placing it in series with the unselected battery and switching the cells of said unselected battery to control a charging current of said auxiliary battery.

[0025] According to a particular feature, the control unit is configured to control a charge of the non-selected battery by a connection on said charge / discharge unit.

[0026] According to another feature, the control unit is configured to control a connection of the auxiliary battery in series with both the first battery and the second battery to charge the auxiliary battery using a current (I_R) present on the DC power supply bus.

[0027] According to another feature, the control unit is configured to control the supply of a variable voltage to said charging / discharging unit by connecting the first battery or the second battery to said charging / discharging unit.

[0028] The invention finally relates to a use of the system as defined above in an electric or hybrid vehicle to power one or more electrical devices of said vehicle. Brief description of the figures

[0029] Other characteristics and advantages will appear in the detailed description which follows, made in conjunction with the figures appended and listed below:

[0030] - Figure 1 schematically represents the electrical architecture of the system; - Figure 2 schematically represents the control architecture of the system; - Figure 3A, Figure 3B and Figure 3C represent the electrical architecture of the figure 1, ordered to apply the three operating modes of the system; - Figure 4 illustrates the principle of charging the auxiliary battery when charging on the network; - Figure 5 illustrates the principle of permutation between the two batteries of the system, allowing the supply of DC voltage to be maintained; - Figure 6 shows an exemplary embodiment of the transformer which can be used in the system of the invention; - Figure 7 represents an example of the embodiment of a switched cell battery;

[0031] Detailed description of at least one embodiment

[0032] In the remainder of the description, the term DC means "Direct Current" for direct current, the term AC means "Alternating Current" for alternating current. We will also speak of AC voltage to express a variable voltage and of DC voltage to express a direct voltage.

[0033] The invention relates to a system for supplying electrical power to electrical equipment. The system is particularly well-suited to being installed in an electric or hybrid vehicle. It is then installed on board the vehicle and can contribute to the vehicle's traction or to the power supply of various pieces of equipment in the vehicle.

[0034] The system comprises a DC power supply bus comprising two power supply lines L1, L2 between which a first DC voltage U_DC can be applied. This voltage can be generated directly by a battery pack of suitable capacity. For a battery pack used in an electric or hybrid vehicle, this first voltage can be, for example, 48V DC or 400V DC. Furthermore, in the event of braking of the electric vehicle or during recharging via the thermal engine of a hybrid vehicle, a recharging current can appear on the bus.

[0035] The electrical power supply system thus comprises at least one battery pack.

[0036] In the context of the invention, the battery pack comprises at least a first battery BATT1 and a second battery BATT2.

[0037] Each battery may comprise several modules, each module comprising several electrical energy storage cells.

[0038] By cell is meant an elementary cell or a group of elementary cells placed in series and / or in parallel. By elementary cell, it can be a storage element (battery cell, electrical capacitor, micro-battery, etc.), a generator (fuel cell, Zinc-air cell, photovoltaic cell), or a combination of the two (generator associated with a buffer storage element).

[0039] A battery pack is intended to provide a first direct voltage U_DC as output. (e.g. 48V DC or 400V DC) available on the DC power bus.

[0040] According to a feature of the invention illustrated by [fig.7], each battery (BATT in [fig.7]) of the pack is produced according to a so-called switched cell architecture. This solution makes it possible to replace the converter (DC / DC or DC / AC) at the output of the battery pack. In this architecture, each cell Cell_x can be controlled individually. Several cells connected in series and / or parallel can form a module M_y. Each cell of the battery pack can in fact be switched between an active state and an inactive state thanks to switching means S_xl, S_x2 adapted connected in series and parallel of its capacity C_x (battery, capacitor or super-capacitor type). A control system is then responsible for controlling the switching means to vary the voltage supplied by each battery in its entirety.This type of architecture is well known and notably described in patent applications No. WO2013 / 007810A1, WO2012 / 117111A1, WO2012 / 117110A2, WO2012 / 117 / 109A1 or US9493090B2.

[0041] With reference to [fig.l], the two batteries BATT1, BATT2 of the system are mounted in parallel between the two power supply lines L1, L2 of the DC power supply bus and form two separate branches, called the first branch carrying the first battery BATT1 and the second branch carrying the second battery BATT2. The two batteries can thus work redundantly to supply the DC voltage on the DC power supply bus. When one of the two batteries supplies the voltage U_DC of the DC power supply bus, the other battery can be charging on the AC network or ensure the supply of an AC voltage for components external to the system.

[0042] In this way, the system may be able to permanently maintain the voltage U_DC on the bus, by selectively connecting one or the other of the two branches.

[0043] The first branch and the second branch each comprise two connection terminals, a first terminal (B1 for the first branch and B3 for the second branch) intended to be connected to the first supply line L1 of the bus and a second terminal (B2 for the first branch and B4 for the second branch) intended to be connected (directly or indirectly) to the second supply line L2 of the bus. We will see below that switching means are arranged to manage the selective connection of each branch to the continuous supply bus.

[0044] Furthermore, the system includes a third battery, called the auxiliary battery B_AUX. For example, it may be a lead-acid battery, or an iron-phosphate battery, capable of supplying a voltage of 12V or 24V. It can, for example, power the vehicle's on-board network, i.e., for example, the headlights, windows, ABS braking, steering assistance, but also much more basic functions such as centralized opening / closing by remote control. The battery auxiliary B_AUX has two terminals B5, B6 to integrate into the system.

[0045] The system may further have a transformer TR, forming a charge / discharge unit and comprising two so-called input terminals B7, B8 and two so-called output terminals B9, B10. Its two output terminals may be connected to the AC network to recharge the system. Furthermore, it is also possible to provide an AC voltage at the output of the transformer, between its two output terminals B9, B10, from a rectified voltage U_AC_r (for example 48V rectified AC) supplied by one or other of the two batteries between the two input terminals B7, B8 of the transformer. To recharge on the network, the cells of the battery (BATT1 or BATT2) under charge are switched in a suitable manner to synchronize with the AC network. To achieve this, the switched architecture battery, which must be recharged on the AC network, is controlled by the control system so that the AC current of the battery is perfectly in phase with the network voltage.An algorithm, having as input data the AC network voltage or its rectified image as well as the exchange current between the network and the battery, regulates the exchanged current with respect to a setpoint current, which is itself substantially in phase with the network voltage. In a particular embodiment, the potential difference at the input (between terminals B7-B8) is, via the operation of the transformer TR, a reproduction of the potential difference present between the output terminals (B9-B10) attenuated and rectified. The current setpoint is then an image of the rectified network voltage, or a rectified sinusoidal signal substantially in phase with the rectified network voltage.

[0046] The transformer can be of any type and formed from an assembly of several components, allowing the batteries to be recharged on the AC network and an AC voltage to be supplied. An example of an embodiment is shown in [fig.7] and will be described below.

[0047] According to a particular aspect of the invention, the complete system can operate according to the following different modes:

[0048] - First operating mode (M0D1) called normal: Supply of a constant DC voltage (for example 48V DC or 400V DC) on the DC power bus, without the presence of the network. A single battery or both batteries can be connected to the bus to fix the DC voltage. One of the two batteries can also be configured to control a charging current for the auxiliary battery. - Second operating mode (M0D2) charging on the bus (in regeneration mode or charging via the thermal engine): The system uses the current generated on the DC power bus to charge. One of the two batteries or both batteries BATT1, BATT2 can be charged simultaneously using the current present on the bus. It is also possible to control one of the two batteries to drive a charging current for the auxiliary battery B_AUX, the other battery then absorbing the current difference between the current flowing on the bus and the current absorbed by the battery that manages the charging of the auxiliary battery B_AUX. Alternatively, it is also possible for the two batteries to contribute in parallel to the charging of the auxiliary battery B_AUX, while maintaining a constant DC voltage on the BUS. - Third operating mode (M0D3) charging on the AC network: The system synchronizes one of the two batteries (BATT1 or BATT2) to the AC voltage of the network to charge via the transformer TR. Only one of the two batteries is thus charged on the network, the second battery having to maintain the DC voltage of the BUS (e.g. 48V DC or 400V DC). When charging the battery on the network, the system can also connect the auxiliary battery B_AUX in series and control a charging current of the auxiliary battery B_AUX. The same principle applies when supplying a voltage U_AC outside the system (whether to supply power to an electrical network or to supply an external load). In the latter case, one of the two batteries is dedicated to supplying the voltage U_AC while the other maintains the supply of a constant DC voltage on the bus.Advantageously, the control of the battery supplying the U_AC voltage can be adapted to the type of device connected to the output (network or load). In particular, if it is the electrical network that is connected to the output (use of the "vehicle to grid" type, better known under the English name "vehicle to grid"), the control of the battery advantageously makes it possible to control the phase and the amplitude of the output current in relation to the network voltage.

[0049] To select the different operating modes and allow charging of the auxiliary battery, the system includes different switching means. Generally speaking, these switching means must allow:

[0050] - Connect each battery BATT1, BATT2 separately to the two bus lines or to the two transformer terminals; - Connect the auxiliary battery B_AUX in series with the first battery and / or in series with the second battery; - Bypass the auxiliary battery B_AUX;

[0051] In other words, it is a question of allowing the choice of connecting between the two lines of the continuous power supply bus or between the two terminals of the transformer:

[0052] - The first battery alone or the second battery alone, or - Both batteries simultaneously, in parallel, or - A first battery + auxiliary battery set in series, or - A second battery + auxiliary battery set in series, or - A set of first battery + second battery + auxiliary battery.

[0053] To achieve these objectives, the system may comprise different switching means. With reference to the appended figures, in a non-limiting manner, the system may thus comprise:

[0054] - First switching means Cl arranged in series with the first battery BATT1 and intended to connect the first battery to the first power supply line of the bus or to the first terminal of the transformer; - Second switching means C2 arranged in series with the second battery BATT2 and intended to connect the second battery to the first bus supply line or to the first terminal of the transformer - Third switching means C3 arranged to connect the first branch between the two bus supply lines, directly or through the auxiliary battery B_AUX; The auxiliary battery is then put in series with the first battery; - Fourth switching means C4 arranged to connect the second branch between the two bus supply lines, directly or via the auxiliary battery B_AUX; The auxiliary battery is then put in series with the second battery;

[0055] By way of example, the first switching means C1 may comprise a first switch S1 arranged between the first terminal of the first branch and the first supply line and a second switch S2 arranged between the first terminal of the first branch and the first terminal of the transformer.

[0056] By way of example, the second switching means C2 may comprise a first switch S3 arranged between the first terminal of the second branch and the first supply line and a second switch S4 arranged between the first terminal of the second branch and the first terminal of the transformer.

[0057] By way of example, the third switching means C3 may comprise a first switch S5 arranged between the second terminal of the first branch and the second supply line and a second switch S6 arranged between the second terminal of the first branch and the first terminal of the auxiliary battery, the second terminal of the auxiliary battery being connected directly to the second supply line.

[0058] By way of example, the fourth switching means C4 may comprise a first switch S8 arranged between the second terminal of the second branch and the second supply line and a second switch S7 arranged between the second terminal of the second branch and the first terminal of the auxiliary battery, the second terminal of the auxiliary battery being connected directly to the second supply line.

[0059] Furthermore, with reference to [fig.2], to manage the operating modes M0D1, M0D2, M0D3, the system comprises:

[0060] - Means for measuring the voltage U_battl at the terminals of the first battery; - Means for measuring the current I_battl flowing through the first branch; - Means for measuring the voltage U_batt2 at the terminals of the second battery; - Means for measuring the current I_batt2 flowing through the second branch; - Means for measuring the voltage U_AC_r between the input terminals of the transformer; - Means for measuring the voltage U_AC between the output terminals of the transformer; - Means of communicating control orders to the various switching means; - Means of measuring the temperature of the cells of each battery in the system;

[0061] The system comprises a control and processing unit UC responsible for managing the different operating modes and controlling the switching means and the cells of each battery to implement the selected operating mode. The control unit thus comprises:

[0062] - Means 10 for monitoring the following quantities: • The voltage U_battl at the terminals of the first battery, • The voltage U_batt2 at the terminals of the second battery, • The voltage U_aux at the terminals of the auxiliary battery, • The current I_battl which flows in the first branch, • The current I_batt2 which flows in the second branch, • The charging current I_aux of the auxiliary battery B_AUX. • The U_DC voltage of the DC power supply bus; • The voltage U_AC present on the output terminals of the transformer • The voltage U_AC_r present on the transformer input terminals; - Means 20 for determining and monitoring the state of charge SOC_battl of the first battery, the state of charge S0C_batt2 of the second battery and the state of charge SOC_aux of the auxiliary battery, from the values ​​of the monitored quantities; Means 30 for determining the operating mode (MOD1, MOD2 or MOD3) to be applied, taking into account different constraints): • Maintaining the U_DC voltage on the bus at a substantially constant level; • Maintaining the state of charge of the first battery and the second battery above a determined threshold or at substantially identical levels (e.g. voltage balancing, or state of charge balancing possibly weighted by temperature, aging, power availability, etc.); • Maintaining the charge state of the auxiliary battery above a determined threshold; Means 40 for determining the charging current I_aux_c to be applied to the auxiliary battery B_AUX; This may involve, depending on the state of charge of the auxiliary battery, modulating the intensity of the charging current I_aux_c to optimize the quality of the recharge. At a low state of charge SOC_aux of the auxiliary battery, a high charging current can be supplied and at the end of charging a reduction in its intensity will allow a deeper recharge. In all cases, a maximum charging current must not be exceeded. This maximum charging current can be determined a priori by the manufacturer, for example depending on the temperature and provided that the authorized voltage range is not exceeded. In an optimized manner, this maximum charging current can depend on the state of charge of the auxiliary battery B_AUX, its state of health and its internal impedance, so as to extend its service life without excessively penalizing its recharge time.Then, in the application, one of the objectives is to keep this auxiliary battery B_AUX charged as much as possible so that it remains fully available. This involves taking advantage of all the phases where the current is negative on the DC bus and / or in the presence of AC charging power from the network to keep it charged. It should be noted that the worst case operation can be the so-called "normal" mode M0D1 explained above, in which the auxiliary battery B_AUX is not necessarily recharged. In this case, the auxiliary battery is not recharged until its state of charge SOC_aux is critical and below a threshold. If the current requested on the DC bus is not too high, one of the two batteries BATT1 or BATT2 can switch to current regulation mode to recharge the auxiliary battery B_AUX. The sizing of the relative capacities (in Ah) between the auxiliary battery and the two batteries. BATT1, BATT2 is such that most of the time both batteries BATT1, BATT2 need to be recharged before the auxiliary battery is too discharged, so this charging method remains relatively rare. It can satisfy extreme cases, such as the vehicle at a standstill or at slow speed (low power drawn from BATT1 and BATT2) while accessories such as power steering draw a large current from the auxiliary battery. - Means 50 for generating commands to the switching means to place the system in the selected operating mode and to the switched cells Cell_Battl, Cell_Batt2 of one or other of the batteries to adjust the charging current of the auxiliary battery B_AUX;

[0063] In each of the three operating modes set out above, it is possible to provide a connection of the auxiliary battery B_AUX to charge it, as detailed below:

[0064] First operating mode - [fig.3A]: One of the two batteries, for example the second battery BATT2, is connected to the DC power bus to provide the voltage U_DC on the bus and the auxiliary battery B_AUX can be connected in series with the other battery, respectively the first battery BATT1. A current I_batt2 can be generated by the second battery BATT2. The first battery BATT1 is thus connected to the bus to draw a charging current I_battl and is controlled by the control unit to provide the charging current I_aux adapted to the charging of the auxiliary battery B_AUX. Of course, it is possible to reverse the operation between the first battery and the second battery.

[0065] [Fig.3A] illustrates the system architecture for implementing this first operating mode. In this [Fig.3A], we can see that:

[0066] - The second branch is connected to the DC power bus, by closing switch S3 and switch S8. - The first branch is connected to the DC power bus via the auxiliary battery, by closing switch SI and switch S6.

[0067] A variant of this operating mode consists of connecting the two batteries BATT1 and BATT2 to the DC power bus to provide the voltage U_DC on the bus, and disconnecting the battery B_AUX from the batteries BATT1 and BATT2 by opening the switches S6 and S7. This operating mode may be of interest if high power is required on the bus.

[0068] Second operating mode - [fig.3B]: A current I_R is generated on the DC power supply bus (in regenerative mode during braking or generated by the vehicle's thermal engine). This current I_R can be used to charge the auxiliary battery. The auxiliary battery B_AUX is thus connected in series with at least one of the two batteries, for example the first battery BATT1 and the latter is connected to the bus and controlled by the control unit UC to generate the charging current I_aux suitable for charging the auxiliary battery B_AUX. The second battery BATT2 can also be connected to the bus to charge with the current I_R available on the bus.

[0069] [Fig.3B] illustrates the system architecture for implementing the second operating mode. In this [Fig.3B], we can see that:

[0070] - The second branch is connected to the DC power bus, by closing switch S3 and switch S8. - The first branch is connected to the DC power bus via the auxiliary battery, by closing switch SI and switch S6.

[0071] Depending on the desired charging current for the auxiliary battery B_AUX, the second battery BATT2 can also be connected in series with the auxiliary battery B_AUX by closing the switches S3 and S7 and opening the switch S8. The auxiliary battery B_AUX then sees the entire charging current I_R.

[0072] It should be noted that when the auxiliary battery B_AUX is connected in series with the two batteries BATT1, BATT2 at the same time, the charging current I_aux of the auxiliary battery may not be regulated and then corresponds directly to the charging current I_R.

[0073] Third operating mode - [fig.3C]: One or the other of the two batteries (BATT1) is charged on the AC network via the transformer TR. If necessary, the other battery, which is not charging, can continue to supply the DC voltage. The recharging of the auxiliary battery B_AUX can be carried out through the charging branch connected to the AC network. Its charging is controlled according to the network voltage level, the current passing through the cells of the battery BATT1 and according to its state of charge. As soon as the network voltage is higher than 12V, it is possible to connect the auxiliary battery B_AUX. The connection time of the auxiliary battery B_AUX depends on its state of charge.

[0074] [Fig.3C] illustrates the system architecture for implementing the third operating mode. In this figure, we can see that:

[0075] - The second branch is connected to the DC power bus, by closing switch S3 and switch S8. - The first branch is connected to the transformer via the auxiliary battery, by closing switch S2 and switch S6. In this configuration, it should be noted that it may be necessary to open switch S6 and close switch S5 when the potential difference between the transformer input terminals B7 and B8 falls below the voltage U_aux present at the auxiliary battery terminals.

[0076] [Fig.4] illustrates the operating principle of the third operating mode. This figure represents a time diagram schematically illustrating the principle of connection and disconnection of the auxiliary battery B_AUX during its charging. In this diagram, it can be seen that when the voltage U_AC exceeds 12V, the auxiliary battery B_AUX is connected for a duration Tl. In this configuration, as the auxiliary battery B_AUX sees all the charging current of the battery to which it is connected, to adjust the power delivered to the auxiliary battery, it is disconnected for a period T2. This disconnection period T2 can be of any width between 0 and the time distance which separates the beginning of the period Tl to the end of the period T3. Similarly, its temporal position can be any, from the moment when the period T2 falls between the beginning of the period Tl and the end of the period T3.Alternatively, between the start of period T1 and the end of period T3, period T2 can be distributed in the form of several disconnection zones.

[0077] The diagram shown in [fig.5] shows how to swap the two batteries BATT1, BATT2 without changing the principle of recharging the auxiliary battery when recharging on the AC network.

[0078] To invert the functions performed by each branch of the pack and thus maintain the voltage U_DC, the control unit UC must follow the following steps:

[0079] - Initially, one of the two batteries (BATT1) provides voltage U_DC and the other battery (BATT2) is connected to the transformer to provide a useful AC voltage outside the system or to charge on the AC network; - A tl: Control the switching of the cells of the second battery BATT2 to stop charging (at zero voltage for example). - At t2: Control the second switching means C2 to disconnect the battery BATT2 from the network. - At t3: Control the switching of the cells of the second battery BATT2 to generate the voltage V_DC (for example 48V DC or 400V DC). - At t4: Control the first switching means Cl and the second switching means C2 to connect the first battery BATT1 and the second battery BATT2 to the DC power bus. The two batteries are then in parallel to provide the voltage U_DC. - At t5: Control the switching of the cells of the first battery to stop its supply of the U_DC voltage. - At t6: Control the first switching means Cl to disconnect the first battery BATT1 from the DC power supply bus. - At t7: Control the switching of the cells of the first battery BATT1 to follow the network voltage U_AC.

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] - At t8: Control the first switching means to connect the first battery BATT1 to the network (or to provide a useful voltage outside the system). The principle of connecting the auxiliary battery, as explained above in connection with [fig.4], remains valid when switching between the two main batteries. With reference to this [fig.6], even if it is not part of the core of the invention, it should be noted that the transformer TR can be a simple 50 / 60Hz transformer associated with an active rectifier bridge. The 50 / 60Hz transformer allows the AC network voltage to be lowered before being rectified to generate a voltage compatible with the voltages that the first battery BATT1 and the second battery BATT2 can manage. • When recharging on the network, its rectifier bridge can thus be in passive mode, the equivalent of a diode bridge, or active to reduce losses in the switches. • When generating an AC voltage, for example 110V or 230V AC, its rectifier bridge must be controlled so as to produce positive and negative alternations, the two batteries BATT1 and BATT2 being able to generate only positive arcs. The transformer then sees an alternating voltage, which is essential for its operation. Alternatively, it is also possible to use a so-called "High Frequency" HF transformer, which is less bulky. This involves alternating the polarity of the input voltage at high frequency (typically >10kHz) before passing it through the HF transformer. At the output of this transformer, the HF voltage is rectified and it may be necessary to invert one "low frequency" half-wave in two if negative polarity is to be restored. In [fig.6], below the diagram, we see the actions of each stage on the signal. The operation is bidirectional in power from the moment when suitable commands are sent to the switches. It therefore allows both charging from the network, and the supply of an AC voltage, similar to that of the network, from the batteries. From the above, it is clear that the solution has many advantages, including: - It allows a permanent supply of a constant voltage on the DC power bus, by making the two batteries redundant; - It keeps the auxiliary battery charged in all operating modes; - It allows the supply of the different voltages necessary to achieve the operating modes without special DC / DC or DC / AC converters specific; It provides AC voltage for components external to the system.

Claims

1. Claims Electrical power supply system for electrical equipment, which includes: - A continuous power supply bus, - A first battery (BATT1) capable of supplying a first direct voltage on said direct power supply bus, said first battery comprising first switchable cells, - An auxiliary battery (B_AUX) configured to provide a second direct voltage (U_AUX), separate from the first direct voltage, - A control unit (CU), - Characterized in that it includes: - A second battery (BATT2) capable of supplying said first direct voltage on said direct power supply bus, said second battery being connected in parallel with said first battery, said second battery comprising second switchable cells, - First switching means (Cl) arranged to connect or disconnect the first battery from the continuous power supply bus, - Second switching means (C2) arranged to connect or disconnect the second battery from the DC power supply bus, - Third switching means (C3, C4) configured to connect or disconnect the auxiliary battery in series with the first battery and / or in series with the second battery, - Said control unit (CU) being configured to: • Select at least one battery from the first battery and the second battery to fix said voltage on the DC power bus by connecting it to the DC power bus, • Order a connection to the DC power bus of the unselected battery, and a charge of said auxiliary battery (B_AUX) by placing it in series with the unselected battery and switching the cells of said non-selected battery to control a charging current (I_aux) of said auxiliary battery.

2. System according to one of claims 1, characterized in that the first switching means (Cl) are arranged to connect or disconnect the first battery to a charge / discharge unit intended to be connected to an alternating network.

3. System according to claim 2, characterized in that the second switching means (C2) are arranged to connect or disconnect the second battery to said charging / discharging unit.

4. System according to claim 2 or 3, characterized in that the control unit (UC) is configured to control a charge of the battery not selected by a connection on said charge / discharge unit.

5. System according to one of claims 2 to 4, characterized in that the control unit (UC) is configured to control the supply of a variable voltage to said charge / discharge unit by connecting the first battery or the second battery to said charge / discharge unit.

6. System according to one of claims 1 to 5, characterized in that the control unit (UC) is configured to control a connection of the auxiliary battery (B_AUX) in series with both the first battery (BATT1) and the second battery (BATT2) to charge the auxiliary battery using a current (I_R) present on the DC power supply bus.

7. System according to one of claims 1 to 6, characterized in that the control unit comprises means (10) for monitoring the following quantities: • The voltage (U_battl) at the terminals of the first battery, • The voltage (U_batt2) at the terminals of the second battery, • The voltage (U_aux) at the terminals of the auxiliary battery, • The current (I_battl) which flows in a first branch carrying the first battery, • The current (I_batt2) which flows in the second branch carrying the second battery, • The charging current (I_aux) of the auxiliary battery (B_AUX). • The voltage (U_DC) of the DC power supply bus;

8. System according to claim 7, characterized in that the control unit (UC) comprises means (20) for determining and monitoring the state of charge (SOC_battl) of the first battery, the state of charge (S0C_batt2) of the second battery and the state of charge (SOC_aux) of the auxiliary battery, from the values ​​of the monitored quantities.

9. System according to one of claims 1 to 8, characterized in that the control unit comprises means for controlling the charging current (I_aux) of the auxiliary battery (B_AUX) by applying connection phases and disconnection phases of the auxiliary battery to said non-selected battery.

10. System according to one of claims 1 to 9, characterized in that the first battery and the second battery each comprise several cells connected in series and parallel, each cell comprising at least one capacitor and switching means.

11. Control method implemented in the control unit (UC) of an electrical power supply system as defined in one of the preceding claims, characterized in that it comprises the following steps: - Selecting at least one battery from the first battery or the second battery to supply said voltage on the DC power supply bus by connecting it to the DC power supply bus, - Controlling a connection to the DC power supply bus of the non-selected battery, and a charge of said auxiliary battery (B_AUX) by placing it in series with the non-selected battery and by switching the cells of said non-selected battery to control a charge current (I_aux) of said auxiliary battery.

12. Method according to claim 11, characterized in that the control unit is configured to control a charge of the battery not selected by a connection to a charge / discharge unit.

13. Method according to claim 11 or 12, characterized in that the control unit is configured to control a connection of the auxiliary battery in series with both the first battery (BATT1) and the second battery (BATT2) to charge the auxiliary battery (B_AUX) using a current (I_R) present on the DC power supply bus.

14. Method according to claim 12, characterized in that the control unit (UC) is configured to control the supply of a variable voltage to said charge / discharge unit by connecting the first battery or the second battery to said charge / discharge unit.

15. Use of the system as defined in one of claims 1 to 10 in an electric or hybrid vehicle to power one or more electrical devices of said vehicle.

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