ENERGY STORAGE DEVICE FOR A DISTRIBUTED INVERTER BATTERY COMPRISING A SECONDARY BYPASS CIRCUIT

Abstract

The present invention relates to an energy storage device (MCLk) comprising an energy storage element (CLk) providing a voltage (Vclk) and a main switching circuit (COMk) forming an H-bridge whose states are selectively controllable, the energy storage element (CLk) being capable of delivering to said connection terminals, in a first state the voltage (Vclk), in a second state the inverted voltage and in a third state a zero voltage configuring the storage device (MCLk) in a bypass state of the storage element (CLk), and further comprising a secondary bypass circuit (CCk) of the main switching circuit (COMk) electrically connected to the first and second connection terminals (S1, S2) capable of configuring a fourth redundancy bypass state of the main switching circuit (COMk). Figure 1.

Description

Title of the invention: ENERGY STORAGE DEVICE FOR A DISTRIBUTED INVERTER BATTERY COMPRISING A SECONDARY BYPASS CIRCUIT

[0001] The field of the invention relates to an energy storage device comprising a secondary bypass circuit for an electrical system.

[0002] The applicant has developed a battery architecture known as a distributed multi-level inverter which makes it possible to dispense with the voltage converters usually integrated between a battery with electrochemical cells and the power supply network operating at alternating voltage. This architecture has been the subject of several patent applications. Examples include documents WO-A1-2017 / 153366 and WO-A1-2021 / 048477. They describe a cell architecture which comprises current lines formed by storage devices each comprising an electrochemical cell, or a cluster of cells, and a switching circuit forming an H-bridge. The storage devices are connected in series via the switching circuit so as to form the multi-level inverter structure integrated in the battery.More specifically, in this architecture, for each storage device, the energy storage element is connected to two connection terminals via the switching circuit and is capable of delivering to said connection terminals, either in a first state the voltage of the storage element, or in a second state the inverted voltage and or in a third state a zero voltage configuring the storage device in a short-circuit state of the storage element.

[0003] Such an architecture makes it possible to directly power an electric machine of an electrified vehicle for any type of electromobility application (for example, motor vehicle, bicycle, train, truck, scooter, or even off-road, such as an aircraft, or a ship), or in another case of stationary use to be linked to a three-phase network, for example for network compensation or to equip a renewable energy network.

[0004] This type of distributed architecture is likely to be affected by a failure of a cell or an electronic component of the switching circuit. Document FR-A1-2962608 is known from the prior art, describing a redundancy structure for a static converter comprising a main static conversion arm. More specifically, the redundancy structure comprises a backup conversion arm and an electronic switching circuit configured so as to implement the backup arm after the isolation of the main arm. It is therefore a classic solution for redundancy of an electronic circuit. This type of solution has the disadvantage of high cost and in the particular case of the proposed battery architecture, would consist of doubling each storage module or each H-bridge switching circuit with a current line intervening only in the event of failure of one of the two components.

[0005] To avoid an additional cost of cell redundancy, the alternative protection strategy which is therefore provided is that, in the event of failure of a cluster of cells, for example if a cell is at the end of its life or if a problem is detected in measuring the voltage or the temperature of the cluster, a protection controls the switching circuit of the faulty cluster in a bypass state in order to isolate it from the current line while maintaining the latter functional by the other storage devices. The current passes directly through the storage device via the bypass of the switching circuit of the H-bridge. Thus, this architecture has a first level of fault tolerance. However, this tolerance is limited because when the failure occurs on one of the components of the switching circuit of the H-bridge, the bypass state is potentially no longer activatable.

[0006] There is therefore a need to improve the protection of the electrical system in the event of failure of the H-bridge switching circuit. One objective of the invention is to overcome the aforementioned problems. Another objective of the invention is to improve electrical safety for handling the electrical system or a storage module of the electrical system. One objective is to guarantee the continuity of service of the electrical system.

[0007] More specifically, the invention relates to an energy storage device comprising a first and a second connection terminal, an energy storage element supplying a voltage and a main switching circuit forming an H-bridge whose states are selectively controllable, the energy storage element being connected to the two connection terminals via the main switching circuit and being capable of delivering to said connection terminals, in a first state the voltage, in a second state the inverted voltage and in a third state a zero voltage configuring the storage device in a bypass state of the storage element. According to the invention, the storage device further comprises a secondary bypass circuit of the main switching circuit electrically connected to the first and second connection terminals capable of configuring a fourth redundancy bypass state of the main switching circuit.

[0008] The method according to the invention may include the following additional characteristics, alone or in combination:

[0009] - The secondary bypass circuit comprises two controllable transistors mounted in head to tail in common source between the first and second connection terminal.

[0010] - The secondary bypass circuit is capable of being controlled by default in the fourth redundancy bypass state and further comprises a first control circuit comprising a first control means, powered by a first power supply, capable of activating the fourth redundancy bypass state, the first control circuit further comprising a second control means powered by a second power supply capable of activating the fourth redundancy bypass state when the first control means is not operational.

[0011] - The first power supply is provided by an energy source external to the device storage and the second power supply is provided by the energy storage element.

[0012] - The secondary bypass circuit comprises a single bidirectional transistor, which is a transistor in the idle state to activate the fourth redundancy bypass state, and further comprises a second control circuit capable of deactivating the fourth redundancy bypass state.

[0013] - The second control circuit is powered by the energy storage element.

[0014] Further envisaged is an electrical system comprising a power battery with electrochemical cells, the battery comprising at least one current line comprising a plurality of energy storage devices according to any one of the preceding embodiments, said storage devices being connected in series in the current line so as to form a distributed multi-level inverter in the battery capable of generating a voltage waveform chosen at the terminals of the current line as a function of voltage reference setpoints specific to the current line, the system further comprising a control unit capable of controlling each storage device in a bypass state among the plurality of storage devices of the current line, either by activating the main H-bridge switching circuit of said storage device, or by activating the secondary bypass circuit of said storage device.

[0015] The invention further provides an electrified vehicle comprising such an electrical system according to the invention and a stationary energy system comprising such an electrical system according to the invention.

[0016] The invention further provides a method for controlling such an electrical system comprising the following steps:

[0017] - the piloting in an open state of the secondary bypass circuit of each storage device that is detected in nominal operating condition,

[0018] - the control of the secondary bypass circuit of each storage device in a bypass state when a failure is detected on the storage device so as to keep the remaining storage devices on the current line in service.

[0019] According to a variant, the method further comprises a system initialization phase comprising the following successive sub-steps:

[0020] - a first control sub-step during which each secondary circuit of Bypass among a plurality of storage devices of a current line is controlled by default in a bypass state.

[0021] - a second sub-step of determining the operating state of each storage device to determine a nominal operating state or a failure state of each storage device,

[0022] - a third control sub-step until the end time of the phase initialization comprising driving in a bypass state the main switching circuit of each storage device which is detected in a nominal operating state and driving in a bypass state the secondary bypass circuit of each storage device which is detected in a fault state.

[0023] According to a variant of the method, a redundancy bypass state of a secondary bypass circuit is controlled by default by the first control circuit and consists of the configuration of a first control means powered by a first power supply so as to activate the bypass state and in the configuration of a second control means powered by a second power supply so as to activate the bypass state when the first control means is not operational.

[0024] According to a variant of the method, a redundancy bypass state of a secondary bypass circuit is controlled by default by a bidirectional transistor having an on state at rest.

[0025] The invention further provides a control unit for an electrical system comprising means specifically configured to implement the control method according to the invention.

[0026] The invention provides a computer program comprising instructions which, when the program is executed by a control unit, cause the latter to implement any one of the embodiments of the method for controlling the electrical system according to the invention.

[0027] Further provided is a computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to implement the control method according to the invention.

[0028] The invention has the advantage of improving the continuity of service of an electrical system comprising a battery with a multi-level inverter distributed in the battery. The control circuit is further configured to activate the redundancy bypass state by default when the vehicle is stopped or undergoing maintenance. This limits electrical risks during operator intervention on the cells or during transport of the cell modules.

[0029] Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description which follows, comprising embodiments of the invention given as non-limiting examples and illustrated by the appended drawings, in which:

[0030] [Fig-1] represents an embodiment of an electrical system comprising a battery equipped with a distributed multi-level inverter comprising energy storage devices according to the invention.

[0031] [Fig.2] represents a first embodiment of the secondary bypass circuit according to the invention.

[0032] [Fig.3] represents an embodiment of the control circuit of the first mode of realization of the secondary bypass circuit.

[0033] [Fig.4] represents a second embodiment of the secondary bypass circuit according to the invention.

[0034] [Fig.5] schematically represents a method of controlling a system electric according to the invention.

[0035] [Fig.6] schematically represents an electrified vehicle comprising a system according to the invention.

[0036] The invention relates to an electrical system for energy storage for electrified vehicles and stationary storage systems, for example for renewable energy or network regulation installations. The invention applies to any type of electrified vehicle, i.e. comprising an electric motor machine and power electronics, 100% electric or hybrid, preferably motor vehicles, but not only such as aircraft, ships, tractors, bicycles or even scooters or autonomous systems. The system comprises an electrochemical battery comprising cell energy storage devices interconnected so as to form a multi-level inverter structure distributed in the battery making it possible to connect the battery to an electrical system operating in direct voltage and alternating voltage without the intermediary of an inverter.The battery system can be connected directly to a wide-area power supply network and to an electrical driving machine. The invention provides a storage device for ensuring continuity of service of the electrical system in the event of failure of one of the storage devices.

[0037] In the present description, the term distributed multilevel inverter means that the current line or each current line of the battery is formed by a plurality of storage devices connected in series and each storage device comprises a cell or a cluster of cells, as well as a main switching circuit forming an H-bridge, the control unit comprises a means for controlling the storage devices of the current line according to a reference setpoint and is capable of generating a chosen voltage waveform, AC and DC, on each current line. This architecture is described in more detail in [Fig.l]. Furthermore, the bypass state of a storage device means that a bypass configuration of the power circuit between the connection terminals is controlled. This configuration has the effect of disconnecting the storage element in a current line of the battery and isolating it from the other storage elements while maintaining the continuity of service of the system.

[0038] With reference to [Fig.l], the power battery BAT comprises a plurality n of storage devices MCLk forming the multi-level inverter structure distributed in the battery and comprises three current lines LT1, LT2 and LT3 connected to phase branches BPI, BP2 and BP3 and in which the storage devices MCLk are arranged. The storage devices MCLk are connected in series in each current line. The phase branches BPI, BP2 and BP3 make it possible to connect the battery to different systems intended to use an alternating or direct voltage. In this three-phase configuration, each current line comprises n / 3 storage devices. In a variant, the battery comprises a single current line connected to a current line.

[0039] The BAT battery system has a voltage of several hundred volts at its terminals, for example 350 volts or 1000 volts. At 350 volts, each line LT1, LT2, LT3 is equipped, for example, with 24 cell storage devices or cell clusters connected in series. However, depending on the electrical requirements, the BAT battery system has a nominal voltage of only several tens of volts (24V, 36V, 48V for example), in particular for motor vehicle applications, or at a maximum voltage of 1500 volts DC or even higher, in particular for stationary storage systems.

[0040] In a first set of branch connections of the phase branches BPI, BP2 and BP3, the battery system BAT comprises high-voltage switches Kres, also called high-voltage contactors, intended to electrically connect the battery BAT to an extended electrical supply network RES. Each current line LT1, LT2 and LT3 is connected, via these branch connections, on one side to a network connection switch, KR1, KR2 and KR3 respectively, and on the other side to a neutral terminal N of the battery. The extended supply network RES operates at 50Hz or 60Hz alternating voltage and comprises a three-phase line provided with three voltage lines PI, P2 and P3. The battery system BAT is adapted to generate three three-phase voltage waves offset by 2ir / 3. The control of each current line is similar, differing only by a 2ir / 3 offset between them. The power supply network can provide a single-phase voltage line.The battery system is capable of connecting the three current lines in series.

[0041] It should be noted that, thanks to this architecture of multi-level inverter distributed in the battery, the electrical system does not include an AC / DC voltage converter between the current lines LT1, LT2 and LT3 and the phase branches BPI, BP2 and BP3 operating in alternating current.

[0042] Furthermore, in the case of an embodiment for an electrified vehicle, the battery system BAT is the traction battery of the vehicle and further comprises high voltage switches Kmel intended to electrically connect the battery BAT to an electric motor machine MEL. Each current line LT1, LT2 and LT3 is connected, via a second set of derivations of the phase branches BPI, BP2 and BP3, on a first side to a connection switch of the electric machine, KM1, KM2 and KM3 respectively, and on the other side to a neutral terminal N of the battery. The electric motor machine can be an asynchronous or synchronous machine, possibly a direct current machine because the battery system is capable of generating any voltage waveform, alternating or direct.

[0043] Alternatively, for an embodiment of a renewable energy installation, the second phase branch branch assembly may be connected to a photovoltaic installation or a wind turbine installation. Alternatively, the battery is connected to the power supply network for network regulation purposes.

[0044] Furthermore, another set of branches is provided for connecting the battery to a direct voltage bus.

[0045] The battery system BAT further comprises a control unit BMS, one of the functions of which is to control the voltage waveform of each line LT1, LT2, LT3 as a function of a reference setpoint Vref from the storage devices MCLk. Each storage device MCLk may comprise a single cell CLk, or a cluster of cells CLk which may be two, three, four, five, six or more cells, forming the voltage Vclk. The storage device MCLk further comprises a main switching circuit COMk capable of configuring the storage device MCLk in three different states to deliver the voltage Vmclk which is respectively in a first state said voltage Vclk, in a second state the voltage Vclk inverted at the connection terminals of the device MCLk and in a third bypass state a zero voltage. The zero voltage makes it possible to disconnect the cells from the current line.This third state is used during nominal operation of the battery and is also useful in the event of a malfunction of part of the cell cluster, for example a cell at the end of its life, a faulty cell or an anomaly concerning a voltage or temperature sensor. In the event of a failure, the main switching circuit makes it possible to isolate the cell cluster while maintaining continuity of service of the current line, the current passing directly through the storage device via the H bridge which is then . configured in bypass in this third state. Each MCLk storage device has a first terminal S1 and a second terminal S2 for connection. The cells are connected in series, in parallel, or in series and in parallel in a cell cluster.

[0046] The main switching circuit COMk is for example made up of two switching parts forming an H-bridge controllable in the three different states by a control signal from the BMS control unit of the battery BAT specifically addressing the module MCLk. The states are represented by a control variable uik which can take for example the values ​​1, 0, -1 representing the three different states respectively controlling said voltage Vclk, said inverted voltage -Vclk and a zero voltage configuring a bypass state at said connection terminals of the storage device k addressed by the control signal uik. Each main switching circuit COMk comprises electronic components, such as power transistors, possibly of the MOSFET or HEMT type (High Electron Mobility Transistor), controlled by the control signals from the BMS control unit.Thus, the voltage Vmclk across each storage device MCLk among the set of a total of n modules can be controlled according to a control signal uik according to the following relationship: .

[0047] M siV„fi(t)>nk-VM = ' -1 if V^M < -nt- Vai ■ 0 otherwise

[0048] Thus, the BMS control unit can control on each voltage line LT1, LT2 and LT3, any voltage waveform formed by steps of amplitude equal to the voltage Vclk as a function of a reference voltage setpoint Vref by connecting the cells in series via the main switching circuits COMk. The reference voltage setpoint Vref can be of sinusoidal form with a frequency of 50 Hz, any alternating form, for example square, or can be of constant voltage for example.

[0049] Furthermore, according to the invention, each storage device MCLk comprises a secondary bypass circuit CCk of the main switching circuit COMk electrically connected to the first SI and the second terminal S2 for connecting the voltage of the storage device MCLk. The secondary circuit CCk is capable of configuring a fourth redundancy bypass state of the main switching circuit COMk. The bypass state of the main switching circuit COMk can thus be configured in redundancy to guarantee the continuity of service of the electrical system in the event of failure of a component of the storage device, i.e. the storage element, the main circuit or a control circuit of the storage device. Secondary circuit CCk can be controlled in a closed bypass state and in an open state. Preferably, the secondary circuit CCK is controlled in a default redundancy bypass state, i.e. when the electrical system is in standby or shutdown situation, and in an open state by activation of a specific command by the system supervision.

[0050] It is recalled that an electrochemical cell is an electrical energy accumulator having two terminals and presenting a voltage of a few volts, most often between 2.3V and 4.2V, approximately. The cells can be of the Lithium-ion type (a lithium Nickel Manganese Cobalt oxide NMC or a lithium iron phosphate LFP can be cited as examples of positive electrode active materials), Nickel Cadmium (Ni-cd), Nickel-Metal-Hydride (Ni-MH) for example. More precisely, a Lithium-ion cell is composed mainly of a porous positive electrode, a porous negative electrode, a separator and an electrolyte (which can be liquid, polymeric or solid). The operating principle of a Lithium-ion cell is based on the reversible exchange of lithium ions between the two porous electrodes.

[0051] In [Fig.2], a first embodiment of a storage device MCLk is shown schematically. The redundant bypass function is performed by the secondary circuit CCK which comprises two power MOSFET transistors CCkl and CCk2 (“Metal Oxide Semiconductor Field Effect Transistor” in English) mounted head-to-tail in common source electrically connected to the two connection terminals SI and S2 of the storage device in order to ensure the opening of the secondary bypass circuit CCK regardless of the sign of the voltage at its terminals. The H-bridge of the main switching circuit COMk is made up of switches, produced by transistors HS1 and HS2 electrically connected to the positive polarity V+ of the storage element and transistors LSI and LS2 electrically connected to the negative polarity V- of the storage element CLk.The transistors HS1, HS2, LSI and LS2 are, for example, MOSFET power transistors sized similarly to the transistors CCkl and CCk2. The storage element CLk comprises, for example, a group of six electrochemical cells connected in series. The storage device further preferably comprises a snubber circuit SNBk connected in parallel across the terminals of the storage element CLk, designated by the English term "snubber" and consisting of resistors and capacitors.

[0052] In [Fig. 3], a first control circuit CMD1 of the first embodiment of the secondary bypass circuit is shown schematically. This control circuit CMD1 is configured so as to provide control of the transistors CCk1 and CCk2 of the secondary bypass circuit in a state in the default closed position, i.e. when the battery system is stopped when the supervision of the storage device is switched off, or when the battery system is in maintenance disconnected of an electrical network supplying supervision. This control strategy has the advantage of preventing the risk of electrocution when handling the storage element. It is therefore not necessary to use personal protective equipment to handle one of the storage devices in the battery system, nor to integrate a protection mechanism such as a fuse or disconnector to protect against short circuits.

[0053] The activation of the secondary bypass circuit is executed when a first control means 32, powered by a first DC voltage supply VI, is operational to provide a gate control voltage to the transistors CCk1 and CCk2. The first control means 32 is a charge pump comprising a controlled transistor 31, a capacitor 33, a diode 34, the first supply VI and a resistor 35. The charge pump 32 applies, when the transistor 31 receives a command S31, of the square signal type, a voltage provided by the supply VI to the point PL. The voltage V1 is for example a voltage of approximately 12 volts. The voltage V1 may be, for a motor vehicle electrical system application, the voltage of the vehicle's on-board network, for example.

[0054] When transistor 38 is open, the voltage supplied by the second power supply V2, applied to point PI, will, via transistor 39, be applied to the gate control electrodes of transistors CCkl and CCk2 of the secondary bypass circuit CCk which will be controlled closed regardless of the voltage level at the drains of transistors CCkl and CCk2. The transistors are closed and the secondary bypass circuit is conducting. The second power supply V2 is the voltage of the group of cells of the storage device, the voltage of a group of cells of an adjacent storage device in the current line of the battery or of a more distant device, or may be a power supply supplied by a dedicated source.

[0055] It will be noted that the first power supply V1 and the second power supply V2 are separate electrical sources. The second power supply V2 makes it possible to maintain the bypass state by default even when the battery system is undergoing maintenance or disconnected from the on-board network battery in the case of an electrified vehicle application.

[0056] When the charge pump 32 is not operational, in standby, that is to say not powered by the voltage VI or faulty, a second control means 36 of the first circuit CMD1 comprising the diode 41 makes it possible to power the gates of the MOSFET transistors CCkl and CCk2 at the voltage V2 while a discharge resistor 40 pulls the source of the transistors CCkl and CCk2 towards 0 in order to keep the transistors closed in this non-operational state. This activation by default, by the voltage V2 of the cells of the storage device for example, improves the electrical protection.

[0057] In nominal operation, the closing of transistor 38, by activation of a signal S38, sets the potential of the gate electrodes of transistors CCk1 and CCk2 to the potential 0 volts to open said transistors. The secondary bypass circuit is configured in an open state. The opening of a secondary bypass circuit of a storage device is controlled in nominal operation of the battery system when no fault is detected on said storage device. Electronic means, a driver, are provided, capable of detecting a failure of the main H-bridge switching circuit, for example a transistor blocking in the open state, so as to control the secondary bypass circuit in the on state.

[0058] In [Fig.4], a second embodiment of a storage device according to the invention is shown schematically in the form of an isolated electrical circuit, in which the secondary bypass circuit comprises a single bidirectional transistor 42, which in this example may be a power transistor made of GaN (Gallium Nitride) semiconductor material configured in the on state at rest. This has the advantage of simplifying the control circuit of this secondary bypass circuit 42.

[0059] More precisely, in this second embodiment, the main H-bridge switching circuit COMk is formed of power transistors 46, 47, 48 and 49. A second control circuit CMD2 comprises control means comprising a charging capacitor 44, a third power supply V3 and a transistor 43 controlled by a signal S43 making it possible to activate the secondary bypass circuit in the open state. V3 can be a voltage supplied by electrochemical cells of the storage device. When no signal is controlled on the signal S43 of the transistor 43, the voltage across the control terminals of the transistor 42, of the type passing in the rest state, is zero and this transistor 42 is closed. When the signal S43 is activated by a square signal, the capacitor 44 is charged by the third voltage V3, thus the transistor 42 opens.

[0060] It will be noted that the transistors of the main H-bridge switching circuit COMk and of the secondary bypass circuit can be made by any type of power transistors suitable for current conversion applications for an electrified vehicle traction battery and for stationary power battery applications. The switches of the main H-bridge switching circuit and of the secondary bypass circuit can be of identical or different technologies. MOSFET and HEMT transistor technologies are cited as non-limiting examples, other technologies are conceivable such as IGBT transistors (Insulated Gate Bipolar Transistor).

[0061] Furthermore, it is provided according to the invention that the BMS control unit of the electrical system comprising the battery, with reference to [Fig.l], is capable of controlling each storage device, among the plurality of storage devices of the current line, in a bypass state, either by activating the main H-bridge switching circuit of said storage device, or by activating the secondary bypass circuit of said storage device. A control method is further provided specifically for controlling the bypass circuits in the electrical system to improve the continuity of service of the electrical system. The BMS control unit is provided with an integrated circuit computer and electronic memories, the computer and the memories being configured to execute the control method according to the invention. But this is not obligatory. Indeed, the computer could be external to the BMS control unit, while being coupled to the latter BMS. In the latter case, it can itself be arranged in the form of a dedicated computer comprising a possible dedicated program, for example.Consequently, the control unit, according to the invention, can be produced in the form of software modules (or computer modules (or even "software")), or electronic circuits (or "hardware"), or even a combination of electronic circuits and software modules.

[0062] In [Fig.5], a method for controlling the electrical system comprising a battery with a distributed multi-level inverter in the battery is schematically represented in the form of a functional block diagram. In nominal operation, the method for controlling the electrical system according to the invention comprises the following steps of controlling E51 in an open state of the secondary bypass circuit of each storage device which is detected in nominal operating state or operational state and controlling E52 the secondary bypass circuit of each storage device in a redundancy bypass state when a failure is detected on the storage device, either the storage element, or the main switching circuit, or a control circuit, so as to maintain the continuity of service of the remaining storage devices of the current line.

[0063] Furthermore, when starting the electrical system, the method according to the invention comprises an initialization phase E50 of the system comprising successive sub-steps making it possible to improve the electrical protection when stopping the system and when starting once the system is detected in an operational state.

[0064] The method comprises a first sub-step E510 of the initialization phase during which each secondary bypass circuit among the plurality of storage devices of a current line is controlled by default in the redundancy bypass state. The bypass state of the secondary circuit is configured either by a first control circuit whose power supply is provided by the electrochemical cells of the storage device or an external power supply specific for this purpose, or alternatively by a secondary bypass circuit comprising a transistor passing to the resting state. This last variant avoids the use of a power supply to control this state.

[0065] The method comprises a second sub-step E520 for determining the operating state of each storage device to determine a nominal operating state or a failure state of each storage device. This is the startup check making it possible to activate or not the main H-bridge switching circuits in their nominal operation. A failure state can be detected from a means for detecting a blocking state of one of the switches of the main switching circuit.

[0066] Then, the method comprises a third sub-step E530 until the end time of the initialization phase comprising the control in a bypass state of the main H-bridge switching circuit of each storage device which is detected in nominal operating state and the control of the secondary bypass circuit in a redundancy bypass state of each storage device which is detected in fault state. Thus, from the start-up, the faulty devices are isolated from the other devices by the secondary bypass circuit. The operational storage devices are maintained in a bypass state by the main H-bridge switching circuit, as a protective measure, until the start-up of the electrical system is triggered.

[0067] In [Fig.6], an embodiment of the electrical system is shown for an electrified vehicle with a fully electric motor or hybrid motor. The vehicle comprises at least one electrical drive machine 64 capable of transmitting torque to the drive wheels 62 of the vehicle through a transmission 61. The electrical machine 64 may be three-phase. The vehicle comprises an electrical system comprising the battery 60 according to the architecture with a multi-level inverter distributed in the battery in accordance with the description given in [Fig.l]. The battery comprises at least one current line, preferably three current lines.

[0068] The vehicle further comprises an interface for recharging the battery 68 from a power supply network operating at alternating voltage. The recharging interface 68 is a recharging box electrically connecting the terminals of the battery 60 to the terminal for recharging. The recharging interface 68 is also suitable for rapid recharging at direct voltage. The battery system 60 is advantageous in that its control unit 65 adapts the voltage wave to alternating form or to direct wave form without using a voltage converter. The vehicle further comprises a supervision system 66 cooperating with the control unit 65 of the battery system 60. The battery system 60 can be directly electrically connected to the electric motor 64, thus improving its energy efficiency in traction. The battery can also be connected to a voltage bus continuous 63, high voltage, for example operating at a nominal voltage of between 350 and 800 volts, for example 450 volts, and to a low voltage on-board network 67 operating at a nominal voltage of type 12 volts. In addition, the power electronics 69 comprises a DC / DC converter connecting the voltage bus to the on-board network 67 (450 volts / 12 volts) including a service battery. Some or all of the vehicle functions are controlled by the supervision system 66.

[0069] A stationary electrical system is also envisaged, for example for network regulation or for a photovoltaic or wind renewable energy system. This electrical system is a system conforming to that of [Fig.l].

[0070] Whether for an electrified vehicle or for a stationary system, the battery 60 comprises at least one current line comprising a plurality of energy storage devices each comprising a secondary bypass circuit of the main switching circuit configured according to the invention. The storage devices are connected in series in the or each current line so as to form a distributed multilevel inverter in the battery capable of generating a voltage waveform chosen at the terminals of the current line as a function of voltage reference setpoints specific to the current line.The system further comprises a control unit capable of controlling each storage device in a bypass state among the plurality of storage devices of the current line, either by activating the main H-bridge switching circuit of said storage device, or by activating the secondary bypass circuit of said storage device.

[0071] By default, when stopped or during maintenance, for example when the battery system is disconnected from the on-board network in the case of an electric vehicle, the electrochemical cells are isolated by default thanks to the secondary bypass circuit. The invention improves safety during maintenance.

[0072] The invention is described in the above by way of example. It is understood that the person skilled in the art is able to produce different variant embodiments of the invention by associating, for example, the different characteristics above taken alone or in combination, without departing from the scope of the invention.

Claims

Claims

1. Energy storage device (MCLk) comprising a first and a second connection terminal (SI, S2), an energy storage element (CLk) supplying a voltage (Vclk) and a main switching circuit (COMk) forming an H-bridge whose states are selectively controllable, the energy storage element (CLk) being connected to the two connection terminals (SI, S2) via the main switching circuit (COMk) and being capable of delivering to said connection terminals, in a first state the voltage (Vclk), in a second state the inverted voltage and in a third state a zero voltage configuring the storage device (MCLk) in a bypass state of the storage element (CLk), characterized in that it further comprises a secondary bypass circuit (CCk) of the main switching circuit (COMk) electrically connected to the first and the second connection terminals (SI, S2)S2) capable of configuring a fourth redundancy bypass state of the main switching circuit (COMk).,

2. Device according to claim 1 in which the secondary bypass circuit (CCk) comprises two controllable transistors (CCkl, CCk2) mounted head to tail as a common source between the first and second connection terminals (SI, S2).

3. Device according to claim 1 or 2 wherein the secondary bypass circuit (CCk) is capable of being controlled by default in the fourth redundancy bypass state and further comprises a first control circuit (CMD1) comprising a first control means (32), powered by a first power supply (VI), capable of activating the fourth redundancy bypass state, the first control circuit further comprising a second control means (36) powered by a second power supply (V2) capable of activating the fourth redundancy bypass state when the first control means (32) is not operational.

4. Device according to claim 3 wherein the first power supply (VI) is provided by an energy source external to the storage device (MCLk) and the second power supply (V2) is provided by the energy storage element (CLk).

5. A device according to claim 1 wherein the secondary bypass circuit comprises a single bidirectional transistor (42), which being a transistor in the idle state to activate the fourth redundancy bypass state, and further comprises a second control circuit (CMD2) capable of deactivating the fourth redundancy bypass state.

6. Device according to claim 5, in which the second control circuit (CMD2) is powered by the energy storage element (CLk).

7. Electrical system comprising a power battery (BAT) with electrochemical cells (CLk), the battery (BAT) comprising at least one current line (LT1) comprising a plurality of energy storage devices (MCLk) according to any one of claims 1 to 6, said storage devices (MCLk) being connected in series in the current line (LT1) so as to form a multi-level inverter distributed in the battery (BAT) capable of generating a voltage waveform chosen at the terminals of the current line (LT1) as a function of voltage reference setpoints (Vrefl) specific to the current line, the system further comprising a control unit (BMS) capable of controlling each storage device (MCLk) in a bypass state among the plurality of storage devices of the current line (LT1), either by activating the main H-bridge switching circuit (COMk) of said storage device,either by activating the secondary bypass circuit (CCk) of said storage device.,

8. An electrified vehicle comprising an electrical system according to claim 7.

9. A stationary energy system comprising an electrical system according to claim 7.

10. Method for controlling an electrical system according to claim 7, characterized in that it comprises the following steps: - the control (E51) in an open state of the secondary bypass circuit (CCk) of each storage device (MCLk) which is detected in nominal operating state, - the control (E52) of the secondary bypass circuit (CCk) of each storage device (MCLk) in a bypass state when a fault is detected on the storage device so as to keep the remaining storage devices of the current line in service.

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