BATTERY SYSTEM COMPRISING MEANS FOR SYNCHRONIZING VOLTAGE AND CURRENT REGULATION WITH AN ELECTRICAL POWER SUPPLY NETWORK
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-01-05
- Publication Date
- 2026-08-07
AI Technical Summary
Existing battery systems for electromobility and stationary applications suffer from energy inefficiencies due to the need for AC/DC and DC/AC converter stages, which result in energy losses of 10-20% during conversion, and lack the ability to directly connect to an electrical supply network without integration of a power conversion system.
A battery system with a distributed multilevel inverter architecture that includes a control unit for synchronizing voltage waves and regulating current, allowing direct connection to an alternating voltage network, eliminating the need for common voltage converters and optimizing charging and discharging efficiency.
The solution achieves energy efficiencies greater than 96% in electromobility applications and significantly reduces energy losses, enabling cost-effective charging and discharging with minimal energy loss, while ensuring safe connection to the electrical network.
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Abstract
Description
Description Title of the invention: BATTERY SYSTEM COMPRISING VOLTAGE SYNCHRONIZATION MEANS AND CURRENT REGULATION WITH A NETWORK POWER SUPPLY
[0001] The field of the invention relates to an electro-cell battery system chemical compounds comprising elementary cell modules forming a multi-unit inverter levels distributed in the battery.
[0002] = In the stationary field, electrochemical batteries are used in high voltage electrical networks for network regulation purposes and for storage energy generated by photovoltaic and wind installations, in particular. In the automotive sector, rechargeable electrified vehicles include a battery and power electronics equipped with voltage converter allowing to adapt the current and voltage torque delivered by the battery to the different elements on-board electronics of the vehicle. For these vehicles, the power electronics generally includes a charger allowing the conversion of an alternating voltage in direct voltage for recharging the battery from a power supply network extended electrical system operating on alternating voltage.
[0003] — Bidirectional chargers allow battery charging from the network power supply, and discharge to an electrical system external to the vehicle in the cases of so-called V2X applications for “Vehicle to Everything”. We know for example document WO-A 1-2022 / 200144 and document WO-A 1-2021004639A 1 describing a vehicle electrical power supply system comprising a two-phase charger ctional capable of charging the battery from energy from the supply network and to power an external load connected to another vehicle socket provided for this purpose cffct.
[0004] — These battery discharge solutions are intended only for power supply electrical load connected to a vehicle socket and do not provide the function discharge to a power network. In addition, these bidirectional chargers re- require AC / DC and DC / AC converter stages which generally feature energy losses of the order of 10 to 20% of the power delivered during the conversion.
[0005] — We seek to improve the energy efficiency of power supply systems battery. The applicant has developed a breakthrough architecture called multi-inverter distributed levels which make it possible to do without the usual voltage converters fully integrated between an electrochemical cell battery and the network power supply operating at alternating voltage. This architecture has been the subject of several patent applications by the applicant. Examples include documents WO-A1-2017 / 153366, WO-A1-2021 / 048477 and FR-A1-3121797. They describe a cell architecture which comprises current lines formed by elementary modules each comprising an electrochemical cell, or a cluster of cells, and a switching module forming an H-bridge. These documents also describe innovative control methods for this architecture allowing the balancing of the cells in charge state and the generation of polyphase or direct electric current. More specifically, it is possible to generate a voltage and an alternating current at the battery output that can be directly injected into an electric motor or the power supply network. This architecture is particularly efficient because electrical efficiencies in recharging and discharging have been measured that are greater than 96% and because it allows for the elimination of voltage conversion stages for electromobility applications. In stationary applications, particularly for renewable energy installations, where the battery system can store energy or regulate the network by controlled discharge, it is possible to directly connect the battery system to the power supply network without integrating a power conversion system (PCS). It therefore allows for significant financial savings. The aim is to propose an electrical energy storage system that can overcome the aforementioned problems and improve the connection phase of such a system to the electrical network. One objective of the invention is to propose a battery system, for electromobility applications and stationary applications based on this integrated multi-level inverter structure allowing bidirectional operation of the battery system with the AC voltage, single-phase and polyphase electrical supply network. One objective of the invention is to propose a solution that optimizes the regulation of the charging and discharging current on the supply network. More specifically, the invention relates to an electrochemical cell battery system, intended to be recharged / discharged on an extended electrical power supply network operating at alternating voltage, the system comprising at least one current line comprising a plurality of elementary modules, each provided with a cell or a cluster of cells, forming a distributed multilevel inverter and a control unit for the elementary modules capable of generating an alternating voltage waveform chosen at the terminals of the current line as a function of a voltage reference setpoint. According to the invention, the system further comprises: - a means of determining electrical characteristics of a voltage wave of the power supply network, - a means of synchronizing the electrical characteristics of a voltage wave of the current line of the battery system with the wave of the power supply network, - a means of electrical connection of the current line to the power supply network controlled according to a state of synchronization of the voltage waves of the battery system and the network, - a means of regulating the current of the battery system by controlling the voltage reference setpoint of the current line of the battery system. The system according to the invention may include the following additional characteristics, alone or in combination: - it comprises three current lines in which the synchronization means comprises a means of transforming the measured voltages of the lines of the battery system and of the network into first vector commands, a means of determining a first voltage setpoint in vector control by a first regulator taking as inputs the first vector commands, and a first means of modulating the first voltage setpoint into a reference voltage setpoint of the battery system; - it comprises three current lines in which the current regulation means comprises a means of transforming measured currents of the lines of the battery system and a reference current setpoint into second current vector commands, a means of determining a second voltage setpoint in vector control by a second regulator taking as inputs the second vector commands and a second means of modulating the second voltage setpoint into a reference voltage setpoint of the battery system; - it further comprises an estimator of the phases of the supply network, and in which the means for transforming the first and / or second vector commands also depend on said phase estimations. - it further comprises an estimator of the voltage amplitude difference between the voltage wave of the supply network and the battery system and in which the synchronization state is dependent on the difference from a predetermined error threshold. The invention further relates to an electrified motor vehicle comprising a rechargeable battery system and an electrical interface for connecting the battery system to an extended electrical supply network for recharging and discharging on the supply network, wherein the battery system is according to any of the preceding embodiments. The invention further relates to a stationary battery system comprising a rechargeable battery system and an electrical interface for connecting the battery system to a wide area power supply network in which the system battery is according to any of the preceding embodiments. Further contemplated is a method of controlling an electrochemical cell battery system for discharging / recharging on an extended power supply network comprising the following successive steps: - determination of electrical characteristics of a voltage wave of the power supply network, - synchronization of the electrical characteristics of a voltage wave of at least one current line of the battery system with the wave of the supply network, - electrical connection of the current line to the supply network in case of detection that the synchronization state of the voltage waves of the battery system and the network is below a predetermined error threshold, - then regulation of the current of the battery system line by controlling a voltage reference setpoint adapted to the control of the current line of the battery system. Alternatively, synchronization involves the following steps: - transformation of measured line voltages of the battery system and the network into first vector commands, - the determination of a first voltage setpoint in vector control by a first regulator taking the first vector commands as inputs, - modulation of the first voltage setpoint in vector control to generate the reference voltage setpoint adapted to the control of the battery system to generate the voltage wave to be synchronized. Alternatively, the current regulation of the battery system comprises the following steps: - the transformation of the measured currents of the battery system lines and of a reference current setpoint into second current vector commands, - the determination of a second voltage setpoint in vector control by a second regulator taking the second vector commands as inputs, - modulation of the second voltage setpoint in vector control to generate the reference voltage setpoint adapted to the control of the battery system to regulate the charge / discharge current of the battery system. The invention further provides the control unit of the battery system according to the invention comprising integrated circuit means specifically configured to implement the control method for recharging and discharging on the electrical supply network. The invention further provides a computer program comprising instructions which, when the program is executed by a control unit of the battery system, cause the latter to implement any one of the embodiments of the control method for recharging and discharge into an electrical supply network. The invention has the following advantages: The current synchronization and regulation process by the control unit improves the safety of recharging or discharging by avoiding overcurrent when closing the high voltage contactors. The energy efficiency during recharging is significantly higher than known state-of-the-art solutions, with around 98.5% observed experimentally. In electromobility applications, the cost of recharging and therefore of using a vehicle is significantly reduced. Furthermore, this charging principle uses the same components whether for charging at 11 kW, 22 kW or even more in three-phase and these same components are used to ensure the vehicle's traction. In a conventional architecture, it is generally necessary to differentiate the conversion components for high-power charging, above 300 kW, and those for traction. This reduces the cost of power electronics. 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: [Fig.1] schematically represents an embodiment of the electrical architecture of the battery system according to the invention; |Fig.2] represents the synchronization and current regulation functions of the battery system according to the invention; [Fig.3] are graphs illustrating the voltage and phase synchronization phase of the current lines of the battery system in accordance with the control method according to the invention; [Fig.4] are graphs illustrating the current regulation phase of the current lines of the battery system in accordance with the control method according to the invention; [Fig.5] represents a method for controlling the battery system according to the invention allowing the recharging and discharging of the battery system on an electrical supply network and the regulation of the current; [Fig.6] schematically represents an embodiment of the battery system for an electrified vehicle. The invention relates to an energy storage system for electrified motor vehicles and stationary storage systems in electrical installations, for example for renewable energy or grid control installations. The system comprises an electrochemical battery comprising modules elementary cells interconnected so as to form a distributed multi-level inverter structure in the battery allowing the battery to be connected to an electrical system operating in direct voltage and also in alternating voltage without the intermediary of an inverter. The battery system can be connected directly to an extensive electrical supply network and to an electrical motive machine. The invention relates more specifically to the means and the method for synchronizing the battery system and for regulating the charging and discharging current on a supply network. In the present description, the term distributed multilevel inverter means that the current line or each current line of the battery, in the case of a polyphase architecture, in particular three-phase, is formed by a plurality of elementary modules and each elementary module comprises a cell or a cluster of cells, as well as a switching module forming an H-bridge, the control unit comprises a means for controlling the elementary modules of the current line according to a reference setpoint and is capable of generating a chosen alternating voltage waveform on each current line. This architecture is the subject of a more detailed description in [Fig.1]. With reference to [Fig. 1], the BAT battery system comprises elementary modules MCLK forming the distributed multi-level inverter structure in the battery and comprises three current lines LT1, LT2 and LT3 in which the elementary modules MCLk are arranged. Alternatively, the BAT battery system may comprise a single current line LT1, only two current lines, or four or more current lines. In summary, the battery system may be single-phase or polyphase. The BAT battery system comprises high-voltage switches Kres, also called high-voltage contactors, intended to electrically connect the BAT battery to the supply network RES. Each current line LTI, LT2 and LT3 is connected 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 RES power supply network operates on AC voltage of 50Hz or 60Hz for example. The BAT battery system can produce three three-phase voltages offset by 2:1 / 3. The control of each current line is similar, differing only by a 27 / 3 offset between them. In the case of an electromobility application, the battery system BAT further comprises high-voltage switches Kmel for electrically connecting the battery BAT to the driving electric machine MEL. Each current line LT1, LT2 and LT3 is connected on one 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 driving electric machine can be a asynchronous or synchronous machine, possibly a direct current machine because the battery system is capable of generating any voltage waveform, alternating or direct current. Furthermore, switches (not shown in [Fig.1]) may be provided to electrically connect the three lines LT1, LT2, LT3 in series so as to allow the connection of the BAT battery to a single-phase network. Alternatively, the BAT battery system may optionally comprise a single current line LT1. 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 LT1, LT2, LT3 line is equipped, for example, with 24 elementary cell modules 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), particularly for automotive applications, or at a maximum voltage of 1500 volts DC or even higher, particularly for stationary storage systems. The BAT battery system further comprises a BMS control unit, one of whose functions is to control the voltage waveform of the LTI line or each LT1, LT2, LT3 line as a function of a reference setpoint Vref from the MCLk elementary modules. Each MCLKk elementary module may comprise a single CLk cell, or a cluster of CLk cells which may be two, three, four, five, six or more cells, forming the elementary voltage Vclk. The MCLK elementary module further comprises a COMK switching module capable of configuring the MCLK elementary module in three different states to deliver the Vmelk voltage which is respectively said elementary voltage Vclk, a zero voltage and the inverted Velk voltage to said connection terminals of the MCLk module. The switching module COMK is for example made up of two switching parts forming an H-bridge that can be controlled 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 that can take for example the values 1, 0, -1 representing the three different states respectively controlling said elementary voltage VcIk, a zero voltage and said inverted voltage -Vclk at said connection terminals of the elementary module k addressed by the control signal uik. Each switching module COMKk comprises electronic components, such as power transistors, possibly of the MOSFET or HEMT (“High Electron Mobility Transistor” type, controlled by the control signals from the BMS control unit.Thus, the voltage Vmclk at the terminals of each elementary module MCLK among the set of a total of n modules can be controlled according to a control signal uik according to the relation . next: [Math.1] L VaokF Ver Un = { 0, Vmicik = 0 k=ln [-L von FY 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 elementary voltage Vclk according to a reference voltage setpoint Vref. The reference voltage setpoint Vref can be sinusoidal in form with a frequency of 50 Hz, any alternating form, for example square, or can be of constant voltage for example. In the context of the invention, the control unit comprises the means for synchronizing the reference voltage setpoint Vref with a network voltage and for regulating a charge and discharge current by regulating the reference setpoint Vref. The BMS control unit is capable of determining at each instant the number q of elementary modules necessary from among the plurality n to produce the voltage waveform for each voltage phase requested by the setpoint Vref and where all the elementary cells have the same elementary voltage Velk. It is recalled that an electrochemical cell is an electrical energy accumulator having two terminals, a positive electrode and a negative electrode, 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, Nickel Cadmium or Nickel-Metal-Hydride type. More precisely, a Lithium-ion cell is composed mainly of a porous positive electrode, a porous negative electrode, a separator and an electrolyte. The operating principle of a Lithium-ion cell is based on the reversible exchange of lithium ions between the two porous electrodes. The cells can for example be of the Lithium iron phosphate, Lithium polymer or solid electrolyte type. With reference to [Fig. 2], the means of the BMS control unit are described which implement the function of synchronizing the voltage waves generated by the battery system and of regulating the charging and discharging current once the battery system is electrically connected to the power supply network. This embodiment concerns the case of synchronization of three-phase voltages. The synchronization function intervenes before electrically connecting the battery system to the power supply network in order to avoid an overcurrent situation at the time of connection. This embodiment described in [Fig. 2] is not limiting, in particular variants of voltage synchronization and current regulation of the battery system which can be single-phase or polyphase, i.e. two-phase, three-phase or more, The BMS control unit is equipped with an integrated circuit calculator and electronic memories, the calculator and memories being configured for the functions involved in synchronization and current regulation. The control unit can be implemented in the form of software modules (or computer modules (or "software")), or electronic circuits (or "hardware"), or a combination of electronic circuits and software modules such as for example ASIC ("Application Specific Integrated Circuit" in English), or DSP ("Digital Signal Processor" in English) type circuits. The BMS control unit comprises means for estimating or measuring the instantaneous electrical characteristics of a voltage wave Vres of each current line of the power supply network. The measurement can be carried out when the battery system is not yet electrically connected to the network. In addition, the control unit comprises means for estimating or measuring the instantaneous electrical characteristics of the voltage Vbat and the current Ibat of each current line of the battery system. With reference to [Fig.2], these means are represented by the inputs Vres, Vbat and Ibat respectively of the BMS control unit. These means make it possible to estimate the value of the voltages Vres of the power supply network. A means 20 is also provided for estimating the phase of each current line of the supply network. It makes it possible to simultaneously estimate the frequency (around 50 Hz or 60 Hz) and the phase shift 201 of the network voltages. The BMS control unit comprises a voltage regulation module 21 whose function is to synchronize the voltage and phase of the power supply network and the battery system and a current regulation module 22 acting to control the charge and discharge current once the battery system is synchronized with the network. The function of the regulation module 21 is to regulate the voltage in amplitude and phase of the battery system voltages by taking the voltages of the supply network as a setpoint. From this regulator 21, the control unit determines a setpoint Vref which controls the control module of the battery cell clusters to generate the voltage waves on each line during the synchronization phase. The regulation module 21 can act either directly on the sinusoidal quantities, or via the control of the direct and quadrature components which are estimated, or by control techniques involving mathematical transforms, for example. In single-phase or polyphase (two-phase, three-phase or more), the regulation module 21 comprises a regulation loop implementing a corrector from estimated electrical characteristics of the battery system and the power supply network to control the voltage setpoint Vref of the line or each current line of the battery system. In the case of a three-phase application, with reference to [Fig. 2], means 210 and 211 are provided for transforming the voltage signals of the supply network Vres and of the battery system Vbat into a digital model of vector commands in the Park plane Vres1 and Vbat 1 respectively with a rotating field at 50 Hz. The resulting vector commands Vres1 and Vbat! are used in a control loop by a corrector 212 to determine a voltage setpoint of the battery system in the form of a vector control setpoint Vsync. In addition, the corrector 212 determines an instantaneous error estimate Verr of the voltage signals. The transformation means 210 and 211 are mathematical and signal processing functions performing a Park transform, known to those skilled in the art in the field of electrical engineering for controlling a three-phase electrical machine. The Park transform has the advantage of simplifying and improving the performance of current and voltage controllers. The possibility of implementing other control principles is not ruled out. The corrector 212 is a known servo-control function that those skilled in the art will be able to adapt for controlling the voltage setpoint. The corrector 212 is for example of the proportional-integral type. Other types of correctors are conceivable. Alternatively, the transformation means 210 and 211 may be estimators of the sinusoidal electrical characteristics of the measured signals or estimators of the direct and quadrature components. A control switching module 23 has the function of selecting the control either in voltage regulation operated during the synchronization phase, or in current regulation once the synchronization is effective. The module 23 uses a control switching block 231 which activates one or the other control mode depending on the estimate of the error Verr between the voltages of the network and the battery system. More specifically, a block 230 compares the error signal Verr with respect to a predetermined threshold. As long as the Verr signal is greater than the threshold, the voltage regulation remains operative. The resulting voltage setpoint Vsync from the regulation block 21 is used to control the battery and generate the waveform on each of the current lines. When the Verr signal falls below the threshold, block 230 detects that the voltage synchronization is consistent in amplitude and phase shift and that the battery system can be electrically connected to the grid. This situation activates the regulation of the battery system current. Since the voltages are synchronized, an overcurrent effect in the battery system is avoided. The block 230 is capable of controlling the Kres high voltage switches referenced in [Fig.1]. When synchronization is detected and maintained stable for a confirmation period, the switches are closed. Furthermore, the BMS control unit includes a modulation function 24 making it possible to deliver a voltage setpoint adapted to the control of the battery system from a voltage setpoint originating either from the voltage regulation module 21 or from the current regulation module 22. For voltage synchronization, the block 240 operates the modulation of the Vsync setpoint at the output of the voltage regulation control loop. Identical to transformation blocks 210 and 211, block 240 takes as input the phase shift estimate 201 of the network voltage signals so that the inverse transformation adapts to any variability in the network phases. In [Fig.3], a graph represents a simulation of the voltage synchronization operation of the battery system. The abscissa is the time axis. This graph represents in the upper frame the voltage of the battery system on a current line and the voltage of the supply network configured in this example in 400 Volts RMS on the corresponding line. The middle frame represents the synchronization error Verr between the voltages of the network and the battery system, expressed in Volts. The lower frame represents the number Qel of cell clusters activated during synchronization. In this example, the current line has 24 cell clusters connected in series in the battery current line. In this graph, we observe that from 0.2 seconds the first clusters of cells of the battery are activated and that the error decreases then stabilizes at the instant of 0.6 seconds. We observe in the upper frame the progressive rise of the battery voltage Vbat by the activation of the cells where 22 of the 24 clusters are used. In parallel, the synchronization error decreases and, after a confirmation period, the control unit controls the closing of the current line contactor and the current regulation is activated. With reference to [Fig.2], the function of the regulation module 22 is to regulate the current of the battery system by taking as input parameters a reference current setpoint Iref and the instantaneous current Ibat estimated on the battery system in Irms value. From this regulator 22, the control unit determines a setpoint Vref which controls the control module of the battery cell clusters to generate the voltage waves on each line during the synchronization phase. Current regulation is carried out by controlling the Vref setpoint of the battery system. Current regulation is carried out by a feedback loop of the measured battery current and a current setpoint. The resulting current flowing through the The battery system is dependent on a voltage amplitude deviation from the grid voltage. By regulating a voltage to a value higher than the grid voltage, a discharge current is controlled, and by regulating a voltage to a value lower than the grid voltage, a recharge current is controlled. The current regulation module 22 can act either directly on the sinusoidal quantities, or via the control of the direct and quadrature components which are estimated, or by control techniques involving mathematical transforms, for example. In single-phase or polyphase (two-phase, three-phase or more), the regulation module 22 comprises a regulation loop implementing a corrector from the measured electrical characteristics of the battery system and a current setpoint to control the voltage setpoint Vref of the line or each current line of the battery system. In the case of a three-phase application, with reference to [Fig. 2], means 220 and 221 are provided for transforming a current setpoint Iref in RMS amperes and the measured current of the battery system Ibat into vector commands in the Park plane Iref1 and Ibat1 respectively with a rotating field at 50 Hz. The resulting vector commands Iref] and Ibatl are used in a regulation loop by a corrector 222 to determine a voltage setpoint of the battery system in the form of a vector control setpoint Vregc. The transformation means 220 and 221 are mathematical and signal processing functions performing a Park transform, known to those skilled in the art in the field of electrical engineering for controlling a three-phase electrical machine. The Park transform has the advantage of simplifying and improving the performance of current and voltage controllers. The possibility of implementing other control principles is not ruled out. The corrector 222 is a known servo-control function that those skilled in the art will be able to adapt for controlling the voltage setpoint. The corrector 222 is, for example, of the proportional-integral type. Other types of correctors are conceivable. Alternatively, the transformation means 220 and 221 may be estimators of the electrical characteristics of the measured signals or estimators of the direct and quadrature components. Each of the transformation functional blocks 210 and 211 for voltage regulation and blocks 220 and 221 for current regulation takes as input the phase shift estimate 201 of the network voltage signals so that the vector controls used in the regulation loop adapt to any variability of the network phases. Indeed, the phases are likely to vary in the event of a load call or an increase in the network's energy production. This improves the accuracy of the synchronization and regulation of the fluent. The Vregc setpoint in vector commands from the current regulation 22 ensures the current control by regulating the voltage setpoint Vref of the battery system for the or each current line. The Vregc setpoint is transmitted to the modulation block 240 once it is detected that the synchronization is compliant to deliver a voltage reference setpoint adapted to the control of the battery system. The same modulation block 240 is used as for the synchronization 21 or another modulation block specific to the current regulation. In [Fig.4], a graph represents a simulation of the current regulation operation of the battery system. The abscissa is the time axis. This graph represents in the upper frame the current setpoint Iref and the resulting current in RMS value of a current line. The middle frame represents the network line current Ires and the corresponding line current of the battery system. The lower frame represents the number Qel of cell clusters activated during current regulation. In this example, the current line has 24 cell clusters connected in series in the battery current line. In this graph, we observe that from 1.15 seconds we control a current setpoint Iref at a value of 16A RMS. Very quickly, the battery current value increases until reaching the setpoint value Iref at the instant of 1.4 seconds. The current regulation dynamics during this transient phase is very fast since the impedance of the electrical circuit is very low. The current convergence is achieved in less than 200 milliseconds. We observe that the shape of the current is stabilized, the current flowing through the clusters IcI is always positive. The alternating current Ires corresponds to the current in the network. In [Fig. 5], a flowchart is shown describing the method for controlling the battery system according to the invention for synchronizing and regulating the charging and discharging current. The method is implemented by the integrated circuit computing means of the battery system control unit. A computer program may be provided by the battery system control unit comprising instructions which, when the program is executed, cause it to implement the control method for synchronizing and regulating the battery system current. The method applies to charging and discharging on a single-phase and polyphase power supply network.Current synchronization and regulation can be performed on one battery current line or several current lines, for example two battery current lines in a two-phase configuration in connection with a two-phase network, three battery current lines in a three-phase configuration in connection with a three-phase network, or four or more current lines. In a first step E1, the method comprises determining electrical characteristics of a voltage wave of the power supply network, in particular the voltage and phase of each current line of the network. The method then comprises the control of the synchronization F2 of the electrical characteristics of the voltage wave of the line or each current line of the battery system with the corresponding power supply network wave. During synchronization the Kres contactors are opened, with reference to [Fig.1]. Synchronization consists of regulating the voltage value and the phase of the battery system by taking the network voltage as a reference. The method provides in a step, during synchronization, the verification E3 of a synchronization state to determine the closing time of the high voltage contactors. The synchronization state is the voltage error between the network wave and the battery voltage wave with respect to a predetermined error threshold. As long as the error is above the threshold, voltage regulation remains active and the resulting voltage setpoint from the regulation controls the battery system. The contactors remain open. As soon as the error becomes lower than the error threshold, the method controls in a step E4 the electrical connection of the line or each current line of the battery system to the supply network. Then, the method controls, in a step ES, the regulation of the current of the or each line of the battery system by taking into account a current setpoint I in RMS value and an estimate of the RMS current of the battery. The method provides for the determination of a voltage setpoint for controlling the voltage wave of the line of the battery system. By generating a voltage amplitude difference between the synchronized voltage waves, either a charging current or a discharging current is generated on the line or each current line of the battery. The voltage and current control loops for E2 synchronization and ES current control in the process consist of a control loop with a correction. In a non-limiting example, the control loop is of the PI correction type. In the case where the battery system and the network are three-phase, the voltage and current control loops for E2 synchronization and ES current control include transformations or estimations of the setpoints and measured values of the battery system into vector controls in the Park plane in a rotating field at 50 Hz. The Park transform has the advantage of simplifying and improving the performance of current and voltage controllers. The possibility of implementing other control principles is not ruled out. Furthermore, the control method according to the invention applies to a system of single-phase or polyphase battery. In single-phase or polyphase configuration, the voltage synchronization step E2 and the current regulation step ES can act either directly on the sinusoidal quantities, or via the control of the direct and quadrature components which are estimated, or by control techniques involving mathematical transforms, for example. In [Fig. 6], an embodiment of the battery system 60 according to the invention is described for an electrified vehicle with a fully electric or hybrid motor. The vehicle comprises an electric motor 64 capable of transmitting torque to the drive wheels 62 of the vehicle via a transmission 61. The electric machine 64 may be three-phase. The vehicle comprises a battery system 60 according to the multi-level inverter architecture distributed in the battery in accordance with the description given in [Fig. 1]. The battery comprises three current lines capable of generating three-phase voltage waves. 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 at alternating voltage in accordance with the method according to the invention.The charging interface 68 is also suitable for rapid charging in direct voltage. The battery system 60 is advantageous in that its control unit 65 adapts the voltage wave into alternating form or 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 high-voltage on-board DC voltage electrical network 63 of the vehicle, for example operating at a nominal voltage of 350 Volts, and to a low-voltage on-board network 67 operating at a nominal voltage of 12 Volts, comprising a battery. The on-board DC voltage networks 63 and 67 can be powered by the battery 60 via an AC / DC converter, if necessary. Likewise, thanks to the invention, the battery 60 can be securely electrically connected to an external extended power supply network, via a charging station operating at alternating voltage after the implementation of the synchronization phase. And the regulation of the charge and discharge current is controlled by the control unit 65 of the battery by regulating the voltage of the lines of the battery system 60.
Claims
Claims
1. Electrochemical cell DC battcric (BAT) system, intended for sc recharge / discharge on an extended power supply network (RES) operating in alternating voltage, the system (BAT) comprising at least one current line (LT1) comprising a plurality of elementary modules (MCLK), each equipped with a cell or a cluster of cells, forming a distributed multilevel inverter and a control unit (BMS) of the elementary modules (MCLK) capable of generate a chosen alternating voltage waveform across the current line (LT1) as a function of a reference setpoint in voltage (Vref), the system (BAT) being characterized in that it comprises furthermore: a means for determining (20) electrical characteristics of a voltage wave of the power supply network (RES), a means of synchronizing (21) the characteristics electrical current line voltage wave (LT1) of the battery system (BAT) with the grid wave power supply (RES), a means of electrical connection (Kres) of the line of current (LT1) to the power supply network (RES) controlled by function of a synchronization state (STE) of the waves of battery system (BAT) and grid (RES) voltage, a means for regulating the current (22) of the battery system (BAT) by controlling the voltage reference setpoint (Vref) of the current line of the battery system (BAT).
2. A system according to claim 1, comprising three current lines (LT1, LT2, LT3) in which the synchronization means (21) includes a means of transforming (210, 211) the measured voltages (Vbat, Vres) of the lines (LT1, LT2, LT3) of the battery system (BAT) and network (RES) in first vector commands (Vresl, Vbatl), a means of determining (212) a first voltage setpoint in vector control (Vsync) by a first regulator taking into account inputs the first vector commands (Vresl, Vbat1), and a first means of modulating (240) the first voltage setpoint (Vsync) into a reference setpoint (Vref) in system voltage battery (BAT).
3. A system according to claim 1 or 2, comprising three lines of current (LT1, LT2, LT3) in which the current regulating means (22) includes means for transforming (220, 221) currents measured (Ibat) of the lines (LT1, LT2, LT3) of the battery system (BAT) and a reference current setpoint (Iref) in seconds current vector controls (Irefl, Ibatl), a means of de- terminate (222) a second voltage setpoint in vector control- torial (Vregc) by a second regulator taking as inputs the second vector commands (Irefl, Ibat1) and a second means to modulate (240) the second voltage setpoint (Vregc) into a voltage reference setpoint (Vref) of the battery system.
4. System according to claim 2 or 3, further comprising an es- estimator (202) of the phases (201) of the power supply network (RES), and in which the transformation means (210, 211, 220, 221) of the first {Vresl, Vbatl) and / or second vector commands (Irefl, Ibatl) also depend on said phase estimates (201).
5. System according to any one of claims 1 to 4, comprising in besides an estimator (212) of the voltage amplitude deviation (Verr) between the voltage wave of the power supply network (RES) and the system battery (BAT) and in which the synchronization state (STE) is dependent on the deviation (Verr) from a predetermined error threshold.
6. Electrified motor vehicle comprising a battery system re- chargeable (60) and an electrical interface (68) intended for connection from the battery system (60) to an extended power supply network for recharging and discharging on the power supply network, in which the battery system (60) is according to any one of claims 1 toasS.
7. A stationary battery system comprising a re- chargeable and an electrical interface for connecting the battery system to an extended power supply network in which the battery system is according to any one of the re- indications 1 to 5.
8. Method for controlling a battery system (BAT) with electric cells- trochemicals for discharge / recharge on a power supply network extended electrical (RES) comprising the following successive stages: The determination (E1) of electrical characteristics of a power supply network voltage wave (RES), The synchronization (E2) of the electrical characteristics of a voltage wave of at least one current line (LT1) of the battery system (BAT) with grid wave power supply (RES), The electrical connection (E4) of the current line to the network power supply in case of detection (E3) that the state of synchronization- nization of battery system voltage waves (BAT) and of the network (RES) is below a predetermined error threshold, Then the regulation (ES) of the line current (LT1) of the battery system (BAT) by controlling a setpoint of voltage reference (Vref) adapted to the control of the line current (LT1) of the battery system (BAT).
9. Control method according to claim 8 wherein the synchronization- nization (E2) includes the following steps: the transformation of measured line voltages (Vbat, Vres) (LTI, LT2, LT3) of the battery system (BAT) and the network (RES) in first vector commands (Vresl, Vbat1), the determination of a first voltage setpoint in vector control (Vsync) by a first regulator (212) taking as input the first vector commands (Vresl, Vbatl), the modulation of the first voltage setpoint in vector control (Vsync) to generate the setpoint of reference (Vref) in voltage to generate the voltage wave at synchronize.
10. A control method according to claim 8 or 9 wherein the re- current regulation (ES) of the battery system (BAT) includes the next steps: the transformation of the measured currents (Ibat) of the lines (LTI, LT2, LT3) of the battery system (BAT) and a setpoint of reference current (Iref) in second commands vec- current torials (Irefl, Ibatl), determining a second voltage setpoint in vector control (Vregc) by a second regulator (222) taking as inputs the second vector commands (Iref1, Ibat1), modulation of the second voltage setpoint in vector control (Vregc) to generate the reference setpoint (Vref) in voltage to regulate the charge / discharge current of the battery system (BAT).