Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
  • H01M10/482—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte for several batteries or cells simultaneously or sequentially
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/543—Terminals
  • H01M50/564—Terminals characterised by their manufacturing process
  • H01M50/567—Terminals characterised by their manufacturing process by fixing means, e.g. screws, rivets or bolts
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/572—Means for preventing undesired use or discharge
  • H01M50/574—Devices or arrangements for the interruption of current
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/572—Means for preventing undesired use or discharge
  • H01M50/574—Devices or arrangements for the interruption of current
  • H01M50/583—Devices or arrangements for the interruption of current in response to current, e.g. fuses
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/502—Interconnectors for connecting terminals of adjacent batteries; Interconnectors for connecting cells outside a battery casing
  • H01M50/509—Interconnectors for connecting terminals of adjacent batteries; Interconnectors for connecting cells outside a battery casing characterised by the type of connection, e.g. mixed connections
  • H01M50/51—Connection only in series
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/50—Current conducting connections for cells or batteries
  • H01M50/502—Interconnectors for connecting terminals of adjacent batteries; Interconnectors for connecting cells outside a battery casing
  • H01M50/514—Methods for interconnecting adjacent batteries or cells
  • H01M50/517—Methods for interconnecting adjacent batteries or cells by fixing means, e.g. screws, rivets or bolts

Definitions

• TITLE METHOD FOR PROTECTING A BATTERY CIRCUIT WITH DETECTION OF A SCREWED ELECTRICAL CONNECTION
• the present invention relates to a method for protecting a battery circuit after detection of a defective or loose screwed electrical connection.
• a battery circuit advantageously comprises a traction battery for an electric motor of a hybrid or electric motor vehicle.
• a battery also called a battery pack, comprising a series of battery modules.
• the modules are electrically connected to each other by connection bars which are screwed by electrical connections to each terminal of the modules.
• a battery in the form of a battery block comprises at least two battery modules connected in series, advantageously six modules, each module comprising an electrochemical cell.
• the set of modules connected in series which forms the battery pack is associated with a circuit having a positive connection terminal and a negative connection terminal for the power supply of a member, advantageously but not only an electric motor.
• an electrochemical cell is a cell generating current by chemical reaction, for example of the lithium-ion (or Li-ion) type, of the Ni-Mh or Ni-Cd type or even lead. Screwed electrical connections, with a connection arranged on each longitudinal side of a connection bar, secure each bar of the connection bar system while ensuring electrical contact between a terminal of a module and its associated connection bar .
• the aim is to be able to detect partial or total loosening of an electrical connection screwed between a connection bar and a battery module before there are serious consequences such as overheating of the battery and at worst a risk fire of the module concerned.
• connection bar making electrical contact between either a battery module and or another element such as a relay, a fuse or a switch or between two other elements.
• a first solution involves dedicated temperature measurements, on the connection bars or in the battery modules.
• the document FR-A-3 051 558 measures the temperature at the level of a contact resistance, thus giving an indication as to the value of the contact resistance.
• a second solution provides for taking dedicated voltage measurements at the terminals of the screwed electrical connections or at the terminals of an assembly consisting of a connection bar comprising an electrical connection screwed to each of its two longitudinal edges.
• a third solution is based on a comparison between, on the one hand, the sum of the voltage measurements of the modules and, on the other hand, the overall voltage measured at the terminals of the battery block.
• the first solution provides inefficient and random detection by lacking precision in the determination of the contact resistance by also requiring means for measuring the temperature.
• the second solution implemented in isolation did not give complete satisfaction due to its low reliability and needs to be reinforced by another detection.
• the third solution does not make it possible to differentiate a drop in voltage due to a module from a drop in voltage due to a loosening of a screwed electrical connection.
• the problem underlying the invention is for a battery pack with several modules connected in series by a screwed electrical connection/connecting bar/screwed electrical connection assembly to detect accurately and as quickly as possible that at least one electrical connection is defective or incorrectly tightened.
• the present invention relates to a method for protecting a circuit comprising a switch and a battery following detection of a defective or loose screwed electrical connection, the battery comprising a group of modules connected by a system of connection, each connection bar connecting two adjacent modules by being fixed at each of its longitudinal ends to one of the two adjacent modules by a respective screwed electrical connection, an overall voltage at the terminals of the circuit being measured and a voltage for each connection bar being measured between two electrical screw connections associated with the bar, characterized in that, if the overall voltage at the terminals of the circuit reduced by a sum of the voltages of the connection bars taken between their two electrical screw connections associated is greater than a first value of predetermined voltage, it is concluded that at least one of the screwed electrical connections of the busbar system connection is defective or loose and the circuit breaker is at least temporarily placed in the open position or a first alert requesting the opening of the circuit breaker is issued.
• the present invention provides for comparing the overall voltage measured at the terminals of the battery circuit with the sum of the measurements of the voltages at the terminals of the connection bars and their screwed electrical connections, thus avoiding taking into account a possible module voltage drift that can falsify detection.
• the present invention is particularly well suited to the detection of a defective screwed electrical connection by considering the sum of the voltages of the connection bars taken between their two associated electrical screwed connections, therefore without interference with the possible variations of the modules of the battery and by subtracting this sum from the overall voltage across the circuit. If the difference is too high, it means that the resistance of at least one connection bar has increased abnormally, probably due to a faulty screwed electrical connection.
• the first predetermined voltage value is set between 5 and 10 volts.
• the detection is also applied for screwed electrical connections of auxiliary connection bars connecting a battery module with an element other than a module or two elements other than a battery module.
• the other element or the other elements are individually or in combination the switch, an electrical relay or a fuse.
• the circuit switch when the overall voltage at the terminals of the circuit reduced by a sum of the voltages of the connection bars taken between their two associated screwed electrical connections is greater than the first predetermined voltage value, resistance measurements are taken in force for all the circuit assemblies each consisting of a connection bar and its two screwed electrical connections both between two battery modules and between a battery module and another element or between two other elements, and if the total resistance to terminals of the circuit reduced by a sum of the resistances of all the sets is ten times greater than an average predetermined resistance for a set taken in isolation, it is concluded that the circuit has at least one of its sets which is defective or with at least at least one loose electrical connection, the circuit switch being kept placed in the open position or an order of severity of the alert to request and of the opening of the switch of the circuit being increased, whereas, if the total resistance at the terminals of the circuit minus a sum of the resistances of all the sets is not ten times greater than an average predetermined resistance for a set taken in isolation, the circuit switch is returned to the closed
• the predetermined resistance is equal to 0.05 milliohms.
• the resistance measurement of at least one assembly is ten times greater than the predetermined resistance
• a search for a series electric arc is carried out.
• the series electric arc is representative of a serious fault concerning one or more screwed electrical connections and such research makes it possible to further improve the accuracy of detection.
• the series electric arc is recognizable by a precise voltage drop within a narrow gauge, including a derivative.
• a series electric arc is detected if the overall voltage at the terminals of the circuit reduced by a sum of the voltages of the connection bars taken between their two associated screwed electrical connections is between 25 Volts and 20 Volts and, in the event of a detection of a series electric arc, the circuit switch is placed in the open position with the emission of a fire risk alert.
• the invention also relates to an assembly of a battery circuit and its electronic control unit, characterized in that the control unit comprises means for acquisition, processing by software instructions stored in a memory as well as means control required for the implementation of such a method.
• the electronic control unit is advantageously the battery management unit or BMS already systematically present for monitoring a traction battery of a hybrid or electric motor vehicle.
• the BMS can look for a precise voltage drop within a narrow gauge, for example a derivative as a function of time, which allows the identification of an electric arc.
• the prevention method according to the present invention it is possible to detect small increases in resistance, which however can cause damage when crossed by a strong current, this current possibly being of the order of 400 Amps or more, which makes it possible to prevent a more serious breakdown which would have significant repair costs.
• FIG. 1 is a view of an electrical circuit comprising a battery with several modules connected in series by connection bars fixed to the modules by screwed electrical connections, the method of protecting an electrical circuit according to the present invention that can be applied to such a circuit.
• FIG 1 there is shown a circuit comprising a battery pack comprising N battery modules. Only the first and last modules are referenced respectively 1 and N. In Figure 1, six modules are shown, which is not limiting.
• Each module 1, N comprises at least one electrochemical cell.
• Two adjacent modules are connected by a connection bar 4 carrying an electrical connection 3 screwed to each of its longitudinal ends.
• connection bar 4 carrying an electrical connection 3 screwed to each of its longitudinal ends.
• connection bar 4 carrying an electrical connection 3 screwed to each of its longitudinal ends.
• only one connection bar is referenced 4 and only three screwed electrical connections are referenced 3 but what is stated for these referenced elements is valid for all elements of the same type.
• the circuit comprises two connection terminals with a potential difference or voltage Vp between the terminals, a current intensity traversing the circuit being designated by Ip.
• connection bar 4 For each connection bar 4 connecting two adjacent modules, a voltage V1, V2, V3, VN-2 and VN-1 is measured between the two screwed electrical connections arranged respectively at a longitudinal end of the connection bar 4.
• the present invention relates to a method for protecting such a circuit comprising a switch 6 and a battery following detection of a defective or loose screwed electrical connection 3.
• This protection method therefore comprises a step of detecting one or more defective or loose screwed electrical connections 3.
• the battery comprises a group of modules 1, N connected by a system of connection bars 4.
• Each connection bar 4 connects two adjacent modules by being fixed at each of its longitudinal ends to one of the two adjacent modules by a screwed electrical connection 3 respectively.
• the switch 6 of the circuit is at least temporarily placed in the open position or a first alert requesting the opening of the switch 6 of the circuit is emitted .
• the battery circuit can no longer perform its function of supplying a component such as a motor. It follows that the detection must be reliable because in the case of an electric motor vehicle, the vehicle is stopped or in the case of a hybrid motor vehicle, the electric motor is stopped and it is the heat engine which ensures propulsion.
• the first predetermined voltage value can be fixed between 5 and 10 Volts.
• Vp be the voltage at the terminals of the circuit comprising the battery comprising N modules 1, N and Vk the voltage between two electrical connections of the same connection bar 4 between the module k and the module k+1, the first predetermined voltage value which can be fixed at 10 Volts, if the following inequality is verified, it is detected that at least one of the screwed electrical connections 3 of the connection bar system 4 is defective or unscrewed:
• Vp - ⁇ (Vk) 10
• the overall voltage at the terminals of the circuit reduced by a sum of the voltages of the connection bars 4 taken between their two associated electrical screw connections 3 has previously been determined to be greater than the first predetermined voltage value, it can be carried out resistance measurements in force for the assemblies each consisting of a connection bar 4 and its two screwed electrical connections 3. Each resistance measurement in force can then be compared with a predetermined resistance for such an assembly, this predetermined resistance being known by experience.
• a resistance measurement of at least one set is at least ten times higher than the predetermined resistance, which is a strong sign of abnormality, it can be concluded that said at least one set is defective or that at least one of its two screwed electrical connections 3 is unscrewed.
• the switch 6 of the circuit can be maintained in the open position if such was the case previously after the overall voltage Vp at the terminals of the circuit has been reduced by a sum of the voltages V1 to VN-1 of the connection bars 4 taken between their two associated electrical screw connections 3 has been determined to be greater than the first predetermined voltage value.
• the switch 6 of the circuit can be placed back in the closed position or the order of severity of the warning of opening request can be decreased. Indeed, in this case, the previously detected voltage difference is then probably due to a slight drift of several screwed electrical connections 3 and not to a voltage difference attributable to a single screwed electrical connection 3, which is more severe.
• connection bar 4 For a predetermined resistance of a set of connection bar 4 and its two screwed connection elements of 0.05 itiW or milliohms, bar 4 being between module k and module k+1, if the voltage ratio across the terminals of the assembly Vk to a current flowing in the circuit Ip is greater than 10 times the predetermined resistance, i.e. 0.05 itiW, i.e. if the following inequality is verified, it is detected that the specific connection bar assembly 4 and its two screwed electrical connections 3 is defective with probably at least one of the two electrical screwed connections 3 of the assembly defective or unscrewed:
• auxiliary connection bars 4a, 4b connecting a battery module with an element 5, 6 other than a module or two other elements 5, 6 that a battery module between them.
• the circuit of the battery pack may comprise as an element 5, 6 other than a module 1, N a fuse 5, a switch 6 and/or a relay or any other type of auxiliary element which may be present. in the battery circuit.
• the fuse 5 is electrically connected to the first module 1 by an auxiliary connection bar 4b with screwed electrical connections 3 respectively on the module 1 and the fuse 5.
• the fuse 5 is also electrically connected to the switch 6 by another auxiliary connection bar 4a with screwed electrical connections 3 respectively on the fuse 5 and the switch 6.
• the auxiliary connection bars 4a and 4b can be different from the connection bars 4 between modules 1, N in which case their electrical resistance can be different.
• the screwed electrical connections 3 of the auxiliary connection bars 4a and 4b can be equivalent to the screwed electrical connections 3 of the connection bars 4 between battery modules 1, N.
• auxiliary connection bars 4a, 4b when the overall voltage Vp at the terminals of the circuit reduced by a sum of the voltages V1 to VN-1 of the connection bars 4 taken between their two associated screwed electrical connections 3 is greater than the first predetermined voltage value, resistance measurements can be taken for all the circuit assemblies, each consisting of a connection bar 4 and its two screwed electrical connections 3.
• connection bar 4 between modules 1, N and between a battery module and another element 5, 6 or between two other elements 5, 6, in both cases for assemblies with an auxiliary connection bar.
• the circuit has at least one of its sets which is defective or with at least one loose electrical connection.
• circuit breaker 6 can be held open or a severity order of the circuit breaker 6 open request alert can be increased.
• Vp be the voltage at the terminals of the circuit comprising the battery comprising N modules 1, N, Ip the current intensity in the circuit and Vk the voltage between two electrical connections of the same connection bar 4 between the module k and the module k+1, Vaux the voltage between two electrical connections of the same auxiliary connection bar 4a, 4b, the auxiliary connection bars 4a, 4b being A in number, if we take as average predetermined resistance O,OditiW, a positive detection is illustrated by the following inequality:
• the switch 6 of the circuit is returned to the closed position or the order of severity of the alert is reduced.
• the resistance measurement of at least one set is ten times greater than the predetermined resistance, it can be searched for a series electric arc in the circuit comprising the battery, this to refine the detection and to see if a major fire source problem is present.
• a series electric arc can be detected if the overall voltage at the terminals of the circuit reduced by a sum of the voltages of the connection bars 4 taken between their two associated screwed electrical connections 3 is between 25 Volts and 20 Volts.
• Vp being the voltage at the terminals of the circuit comprising the battery comprising N modules 1
• Vk being the voltage between two electrical connections of the same connection bar 4 between the module k and the module k+1:
• the switch 6 of the circuit can be maintained or placed in the open position with emission of a fire risk alert, therefore of a high order of severity, given that this is the most dangerous situation for the circuit comprising the battery and the organs that the circuit incorporates, in particular one or more battery modules 1, N.
• the invention also relates to an assembly of a battery circuit and its electronic control unit comprising the means of acquisition, of processing by software instructions stored in a memory as well as the control means required for an implementation of a method as previously described.
• the invention is in no way limited to the embodiments described and illustrated which have been given by way of examples only.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Secondary Cells (AREA)

Applications Claiming Priority (2)

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• 2021
  • 2021-06-15 FR FR2106321A patent/FR3123990A1/fr active Pending
• 2022
  • 2022-04-19 CN CN202280042798.9A patent/CN117597813A/zh active Pending
  • 2022-04-19 EP EP22722859.0A patent/EP4356470A1/de active Pending
  • 2022-04-19 WO PCT/FR2022/050728 patent/WO2022263732A1/fr not_active Ceased

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