Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/50—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries acting upon multiple batteries simultaneously or sequentially
  • H02J7/52—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries acting upon multiple batteries simultaneously or sequentially for charge balancing, e.g. equalisation of charge between batteries
  • H02J7/56—Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L50/00—Electric propulsion with power supplied within the vehicle
  • B60L50/40—Electric propulsion with power supplied within the vehicle using propulsion power supplied by capacitors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/34—Parallel operation in networks using both storage and other DC sources, e.g. providing buffering
  • H02J7/342—The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
  • H02J7/50—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries acting upon multiple batteries simultaneously or sequentially
  • H02J7/52—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries acting upon multiple batteries simultaneously or sequentially for charge balancing, e.g. equalisation of charge between batteries
  • H02J7/54—Passive balancing, e.g. using resistors or parallel MOSFETs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L2210/00—Converter types
  • B60L2210/10—DC to DC converters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L2240/00—Control parameters of input or output; Target parameters
  • B60L2240/40—Drive Train control parameters
  • B60L2240/54—Drive Train control parameters related to batteries
  • B60L2240/545—Temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L2240/00—Control parameters of input or output; Target parameters
  • B60L2240/40—Drive Train control parameters
  • B60L2240/54—Drive Train control parameters related to batteries
  • B60L2240/547—Voltage
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L2240/00—Control parameters of input or output; Target parameters
  • B60L2240/40—Drive Train control parameters
  • B60L2240/54—Drive Train control parameters related to batteries
  • B60L2240/549—Current
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L2240/00—Control parameters of input or output; Target parameters
  • B60L2240/80—Time limits
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/72—Electric energy management in electromobility

Definitions

• the invention relates to a load balancing system for electrochemical accumulator power batteries and a corresponding load balancing method.
• Such a battery can be used in particular in the field of electric transport, hybrid and embedded systems.
• the invention particularly relates to lithium-ion (Li-ion) type batteries suitable for such applications, because of their ability to store high energy with a low mass.
• the invention is also applicable to super-capacitors.
• An electrochemical accumulator has a nominal voltage of the order of a few volts, and more precisely 3.3 V for Li-ion batteries based on iron phosphate and 4.2 V for a Li-ion technology based on cobalt oxide. If this voltage is too low compared to the requirements of the system to be powered, several accumulators are placed in series. It is also possible to have in parallel each accumulator associated in series, one or more accumulators in order to increase the available capacity and thus to provide a higher current and power. The accumulators associated in parallel thus form a stage. A stage consists of at least one accumulator. The stages are put in series to reach the desired voltage level. The combination of accumulators is called a storage battery.
• the charging or discharging of an accumulator results respectively in a growth or a decrease in the voltage at its terminals.
• a charged or discharged accumulator is considered when it has reached a voltage level defined by the electrochemical process.
• the current flowing through the stages is the same.
• the level of charge or discharge of the stages therefore depends on the intrinsic characteristics of the accumulators, namely the intrinsic capacitance and the parallel and parallel parasitic internal resistances of the electrolyte or contact between the electrodes and the electrolyte. Voltage differences between the stages are therefore possible due to the manufacturing and aging disparities of the accumulators.
• a voltage too high or too low, called threshold voltage can damage or destroy it.
• the overloading of a Li-ion battery based on Cobalt Oxide can cause its thermal runaway and a fire start.
• overcharging results in decomposition of the electrolyte which decreases its life or can damage the battery.
• the purpose of the monitoring device is to monitor the state of charge and discharge of each accumulator stage and to transmit the information to a control circuit in order to stop charging or discharging the battery when a stage has reaches its threshold voltage.
• the monitoring device is generally associated with a balancing system.
• the balancing system has the function of optimizing the charge of the battery and thus its autonomy by bringing the accumulator stages placed in series to an identical state of charge and / or discharge.
• balancing systems There are two categories of balancing systems, the balancing systems said energy dissipation, or so-called energy transfer.
• the voltage across the stages is standardized by diverting the load current from one or more stages that have reached the threshold voltage and dissipating the energy in a resistor.
• the voltage across the stages is standardized by discharging one or more stages having reached the threshold voltage.
• Energy transfer balancing systems for their part exchange energy between the accumulator battery or an auxiliary energy network and the accumulator stages.
• Energy transfer can be either unidirectional, from the battery to the floors or floors to the battery, or bidirectionally, from the battery to the floors and floors to the battery or from adjacent floor to floor .
• CN1905259 discloses a device for transferring energy from the stages to the battery and which uses an accumulator inductance as a storage element.
• this device does not opt for optimized energy transfer for balancing batteries in transport and embedded applications. Indeed, the end of charge of a battery is determined by the last stage which reaches the threshold voltage. To end the charge of a battery, the energy is taken from one or more stages and it is restored to all stages.
• balancing therefore requires taking energy from all stages at the end of charging to avoid charging at too high a voltage. Balancing is therefore high losses because of the number of large converters in operation.
• the accumulators already at the end of the load are crossed by non-useful AC or DC current components.
• the invention therefore aims to provide an improved balancing system does not have these disadvantages of the state of the art.
• the subject of the invention is a load balancing system for a power battery comprising at least two accumulator stages (s) placed in series, each accumulator stage (s) comprising at least one accumulator, characterized in that said balancing system comprises at least one flyback converter comprising:
• At least one primary winding configured to be connected to the terminals of an accumulator stage (s) of said power battery
• a secondary winding configured to be connected to an auxiliary battery whose voltage is lower than the voltage of said power battery
• a device for controlling said flyback converter comprising at least one processing means for:
• the balancing system may further include one or more of the following features, alone or in combination:
• said system comprises a predefined number of flyback converters respectively associated with a predefined number of modules in series of said power battery, said modules comprising accumulator stages (s) placed in series,
• said system comprises a common flyback converter connected to a predefined number of modules in series of said power battery, said modules comprising accumulator stages connected in series,
• said system comprises, for each accumulator stage (s), a blocking diode connected by its anode to the primary winding of the transformer, and connected by its cathode to the associated switch,
• the blocking diode is a Schottky diode
• said system comprises for each accumulator stage (s) a diode and a transistor in parallel, such that the diode is connected by its anode to the primary winding of the transformer and connected by its cathode to the associated switch of the stage d 'Accumulators),
• the switches of the at least one flyback converter are controlled from common way by said control device so as to be closed at the same time when at least one accumulator stage (s) has a voltage greater than the respective voltages of the other accumulator stages (s), the switches of said at least one flyback converter are individually controlled by said control device so as to control the closing of the switch associated with an accumulator stage (s) whose voltage is greater than the respective voltages of the other accumulator stages (s), said device control device comprises at least one processing means for
• said at least one flyback converter is sized for power transfer from the power battery to the auxiliary battery so as to supply the auxiliary battery
• said system is configured for load balancing the accumulator stages (s) of a lithium-ion power battery
• said system is configured for load balancing accumulator stages (s) of a power battery powering the engine of an electric and / or hybrid motor vehicle.
• Said balancing system may also further comprise one or more of the following characteristics, alone or in combination:
• said balancing system comprises at the terminals of each accumulator stage (s)
• An associated flyback converter comprising a transformer with: a primary winding configured to be connected to the terminals of said associated accumulator stage, and a secondary winding configured to be connected to an auxiliary network whose voltage is less than the voltage of said power battery, and for each accumulator stage (s), a an associated switch connected to a primary winding of said transformer and to the negative terminal of the accumulator stage (s), and said system further comprises:
• a device for controlling said flyback converters respectively comprising at least one processing means for: receiving the voltage information of said monitoring device, and when at least one stage has a voltage greater than the voltage of the other accumulator stages; ), controlling the closing of at least one switch of a flyback converter associated with an accumulator stage (s) and the transfer of energy from said stage to the auxiliary network, so as to balance the charge of the accumulator stages ;
• said transformer is a planar technology transformer
• said system comprises a plurality of diodes respectively connected in series with said transformers, said diodes being respectively connected by their anode to the secondary winding of a transformer and by their cathode to said auxiliary network;
• control device is configured to control said converters so as to transfer the balancing energy of said stages to said auxiliary network, and said flyback converters have a galvanic isolation,
• control device is configured to control said converters so as to transfer the balancing energy of said stages to an auxiliary battery whose voltage is lower than the voltage of said power battery,
• control device is configured to control the closing of the switch associated with an accumulator stage (s) whose voltage is greater than the respective voltages of the other accumulator stages (s), said control device comprises at least one processing means for calculating, for each accumulator stage, a closing time of the associated switch, and controlling the closing of the switches respectively during the associated closing times,
• control device is configured to control said converters so as to supply said auxiliary network with the balancing energy of said power battery
• control device comprises at least one processing means for determining the power to be delivered respectively by said stages.
• the invention also relates to a load balancing method for a power battery comprising at least two accumulator stages connected in series, each accumulator stage comprising at least one accumulator, characterized in that said method comprises the following steps:
• the closure of at least one switch of a flyback converter whose transformer has at least one primary winding connected to the terminals of an accumulator stage is controlled of said power battery and connected to said switch, and a secondary winding connected to an auxiliary battery whose voltage is lower than the voltage of said power battery, for a transfer of energy of said stage associated with said at least one switch whose closure is controlled to said auxiliary battery, so as to balance the charge of the accumulator stages.
• such a method is a combined load balancing method for a power battery and an auxiliary battery whose voltage is lower than the voltage of said power battery.
• said method comprises the following steps: for each accumulator stage (s), a closing time of the associated switch of a flyback converter whose transformer has a primary winding connected to the terminals of the accumulator stage (s) and connected to said switch, and a secondary winding connected to the auxiliary battery, and
• the said load balancing method may include the following preliminary steps:
• the measured voltages are compared with a predefined threshold voltage
• said load balancing method may include the following preliminary steps:
• the measured voltages are compared with each other, and
• the most charged accumulator stages are determined so as to calculate longer closing times for the more charged accumulator stages.
• the voltages at the terminals of the accumulator stages are measured at a predefined instant, such as the end of the charging of said power battery.
• FIG. 1 schematically represents a first embodiment of a balancing system for a power battery
• FIGS. 2a and 2b show in greater detail the balancing system of FIG. 1,
• FIG. 3 represents a variant of the balancing system for a power battery comprising several battery stage modules in series
• FIG. 4 represents a variant of the balancing system with a synchronous rectification
• FIG. 5 schematically illustrates various steps of a method of balancing the load of a power battery according to the first embodiment
• FIG. 6 schematically shows a second embodiment of the balancing system for a power battery for supplying an auxiliary battery
• FIG. 7 represents in more detail the balancing system of FIG. 6,
• FIG. 8 schematically illustrates various steps of a combined method of balancing the load of the power battery and the power supply of the auxiliary battery
• FIG. 9 represents in more detail the power battery, an auxiliary battery and the balancing system according to a third embodiment
• FIG. 10 represents a monitoring device and a control device at the terminals of the power battery of FIG. 9,
• FIG. 11 diagrammatically shows a fourth embodiment of the balancing system for a power battery for supplying the auxiliary battery
• FIG. 12 schematically illustrates different steps of a load balancing method of a power battery according to the third embodiment.
• FIG. 1 shows schematically:
• a battery 1 with a high voltage for example between 48V and 750V, for example for powering the engine of a hybrid or electric vehicle, and isolated from the chassis of the vehicle,
• a DC / DC converter 7 between the two batteries 1 and 5 to allow the power supply of the auxiliary battery 5 by the power battery 1 and made with a galvanic isolation to ensure the safety of auxiliaries Al to An.
• the power battery 1 is an accumulator battery (s) 9 (see Figures 2a, 2b).
• This battery 1 may include several accumulators 9 placed in series.
• This battery 1 may also include one or more additional accumulators placed in parallel accumulators 9 in series so as to form accumulator stages (s) 11.
• Each stage 11 may therefore comprise an accumulator 9 or more accumulators in parallel.
• the battery 1 may comprise several modules 13 placed in series, each module 13 comprising a predefined number of accumulator stages 11.
• the battery 1 has two modules 13 each having four stages 11 of accumulator (s). With such a series association of modules 13, it is easy to replace a defective module 13.
• modules comprising, for example, eight, ten or even twelve stages 11 in series, and each stage 11 comprising two, four or even ten accumulators in parallel as required.
• each module 13 can be connected in parallel with another module 13.
• the balancing system 3 comprises:
• control device 19 for controlling the flyback converter 15 so as to balance the load of the stages 11.
• the balancing system 3 may comprise a single flyback converter 15 for the entire battery 1 or more flyback converters 15 respectively associated with a module 13 as shown in FIG. 3. You can easily replace a faulty flyback converter.
• a balancing between the cells of the same module can be achieved by dissipation in resistors or any other system to limit the cost.
• the flyback converter or converters 15 respectively comprise a transformer 21 surrounded by a dotted line, with:
• a flyback converter 15 further comprises on the side of each primary winding 23, a switch 27 made for example by a power transistor for example MOSFET and a protective antiparallel diode. This switch 27 is connected to the negative terminal (-) of the associated stage 11.
• the flyback converter 15 also has on the side of the secondary winding 25 a diode 29 and a capacitor 31 in series.
• a blocking diode 33 such as a Schottky diode, may allow to avoid a transfer of energy between the stages 11 of accumulator (s).
• a Schottky diode makes it possible to limit the voltage drop at the passage of the diode and also makes it possible to have a lower voltage threshold compared with conventional diodes, for example of the order of 0, 3V.
• the voltage differences are very small during charging: the voltages are generally around 3.2V. At the end of the charge, these differences increase to reach 0.5V at the maximum, the maximum charge voltage being 3.7V.
• the protection diode of the transistor in the switch 27, has a voltage threshold of 0.7V, the difference being 0.5V it prevents any discharge of a more charged stage to a less charged stage. It is then not necessary to put a Schottky diode or to use a synchronous rectification to ensure that a battery stage (s) does not discharge into a less charged accumulator stage (s) and that the energy is well transferred to the auxiliary battery.
• the accumulator voltage monitoring device 17 With regard to the accumulator voltage monitoring device 17, it comprises measuring means 17 'across each stage 11. These measuring means 17' are configured to transmit their measurement results to the control device 19.
• the control device 19 comprises meanwhile at least one processing means for:
• the higher voltage stage 11 then imposes its voltage on the primary windings 23.
• the other stages 11 do not discharge due to the presence of the Schottky diode 33.
• the energy of this stage 11 is therefore transferred via the transformer 21 to the auxiliary battery 5.
• the switches 27 may be individually controlled. Thus, the switch 27 associated with the most heavily loaded stage 11 is controlled to be closed.
• each stage 11 has a respective voltage V1, V2, V3, V4.
• the threshold voltage being for example 3.6V.
• the measuring means 17 'across the terminals of the first stage 11 therefore measures a voltage V1 of 3.5V, while the other measurement means 17' respectively measure a voltage V2, V3, V4 of 3.2V.
• the control device 19 compares the measured voltages in step E2.
• the voltage V 1 across the first stage 11 is greater than the voltages V 2 to
• the control device 19 controls the closing of the switches 27 in the step E3. These switches 27 are controlled in a common way and are thus closed at the same time according to a predefined closing time.
• the voltage VI of 3.5V is imposed on the primary windings 23. This voltage
• the Schottky diodes for the respective voltage stages V2, V3, V4 are blocked, which prevents the discharge of these stages 11.
• the primary windings 23 are therefore connected to the most charged stage 11 and this results in an increase in the magnetic flux in the transformer 21.
• only the switch 27 associated with the most voltage-loaded stage 11 is closed. This also results in an increase in the magnetic flux in the transformer 21, the primary winding 23 is connected to this stage 11 more loaded.
• the voltage across the secondary is negative thereby blocking the diode 29.
• the diode 29 becomes conductive and also allows the recovery of the voltage which is then filtered by the capacitor 31.
• the charge of the accumulators 9 is then balanced by transferring the energy of the most charged stage 11 to the auxiliary battery 5.
• This balancing can be done at any time of operation of the vehicle when a consumption is observed on the auxiliary battery 5 or it is possible to charge the auxiliary battery 5.
• a second embodiment is illustrated schematically in FIG. 6. This second embodiment differs from the first embodiment in that the balancing system 3 completely replaces the DC / DC converter 7 of the first embodiment allowing to supply the auxiliary battery 5 and providing galvanic isolation for the safety of auxiliaries.
• the balancing system may be larger and the balancing more powerful.
• the sizing of the components of the balancing system 3 is adapted for such a transfer of energy from the power battery 1 to the auxiliary battery 5.
• control device 19 comprises at least one processing means for:
• each stage 11 has a respective voltage V1, V2, V3, V4. This measurement of tension can be done at a predefined moment such as the end of charge or at a moment of rest.
• the voltage of the accumulator reflects its state of charge. This is not always the case but it makes it easier to illustrate the subject.
• the state of charge differences can only be estimated from the voltage at the end of charging and / or discharging. Otherwise, the voltage differences between accumulators are often too small to be measured at a reasonable cost.
• the threshold voltage being for example 3.6V.
• the measuring means 17 'across the terminals of the first stage 11 thus measures a voltage V1 of 3.3V, while the second and third measurement means 17' respectively measure a voltage V2, V3 of 3.2V, and the fourth means of measurement 17 'measures a voltage V4 of 3.5V.
• the control device 19 compares, at step E200, each voltage measured at the threshold voltage of 3.6V so as to determine the charge rate t x of each stage 11. It is therefore determined for the first stage 11 of voltage VI of 3.3V, a charge rate of 91%, for the second and third stages 11 of respective voltages V2, V3 of 3.2V a charge rate of 88%, and for the last stage 11 of voltage V4 of 3.5V a charge rate of 97%>.
• step E300 a closing time t f of the switches 27 is then calculated. associated with these load rates t x stages 11.
• the closing time t f switches 27 associated with the second and third stages 11 of voltage V2 and V3 will therefore be less than the closing time of the switch 27 associated with the first stage 11 voltage VI, itself less than the closing time of the switch 27 associated with the last voltage stage V4.
• step E200 instead of comparing the measured voltages to a threshold voltage in step E200, they are compared with each other so as to identify the most loaded stages.
• the voltage stage V4 is more charged than the voltage stage VI which is more charged than the voltage stages V2 and V3.
• step E300 then calculates a closing time of the associated switches based on these comparison results so as to more unload the most loaded stages 11.
• the closing time t f of the switches 27 associated with the second and third voltage stages V 2 and V 3 will therefore be less than the closing time of the switch 27 associated with the first voltage stage VI, itself less than the closing time. of the switch 27 associated with the last stage 11 of voltage V4.
• step E400 the switches 27 are closed intermittently according to the closing times calculated so as to discharge the most charged accumulator stages 11 until they reach substantially the same level of charge as the stage 11 of accumulator (s) the least loaded.
• the stages 11 of respective voltages V4 and V1 are discharged more so that they reach substantially the same charge level of the stages 11 less loaded with voltages V2 and V3.
• auxiliary battery 5 is thus powered while balancing the charge of the accumulator stages (s) 9 by transferring the energy of the most charged stage 11 to the auxiliary battery 5.
• the battery 1 comprises several modules 13
• the powers provided by the balancing systems associated with these modules 13 add up to supply the auxiliary battery 5.
• the energy transferred from the power battery 1 to the auxiliary battery 5 is used to balance the charge level of the accumulator stages 11 of the power battery 1.
• a single electronics can realize the two charge balancing functions of the accumulators 9 of the power battery 1 and the power supply of the auxiliary battery 5.
• the balancing system 3 comprises, for each accumulator stage (s) 11, a flyback converter 15 framed in dashed line, and a control device 19 for controlling the flyback converters 15 so as to balance the load of stages 11.
• This third embodiment therefore differs from the first embodiment, in that the balancing system 3 has a flyback converter 15 for each accumulator stage (s) 11 and not a converter 15 for a module 13 or for the Thus, the balancing system 3 comprises a plurality of converters 15 connected in parallel between the two batteries 1 and 5.
• a flyback converter 15 comprises a transformer 21, with a primary winding 23 associated with a stage 11 of accumulator (s), and a secondary winding 25 connected to the auxiliary battery 5.
• transformer 21 with a primary winding 23 and a secondary winding 25 per stage 11 rather than a transformer 21 for several stages 11 makes it possible to choose lower power transformers 21.
• transformers 21 may be provided according to the planar technology on a printed circuit.
• a planar-type transformer comprises a thin magnetic circuit generally machined ferrite, fixed on the printed circuit in which the turns are made.
• a flyback converter 15 further comprises on the side of the primary winding 23, a switch 27 made for example by a power transistor for example MOSFET. This switch 27 is connected to the negative terminal (-) of the associated stage 11.
• the flyback converter 15 also has on the side of the secondary winding 25 a diode 29 in series.
• Each flyback converter 15 associated with a stage 11 is therefore independent of the other flyback converters 15; which allows simultaneous operation of the converters 15 without interaction of a stage 11 on another stage 11.
• the balancing system 3 completely replaces the DC / DC converter 7 of the first variant of the second embodiment making it possible to supply the auxiliary battery 5 and ensuring the Galvanic isolation for the safety of auxiliaries Al to An.
• the power delivered by the balancing system 3 is sufficient to supply the auxiliary network called 12V network, or low voltage network, in the embodiment described.
• the redundancy of the plurality of flyback converters 15 also makes it possible to dispense with the auxiliary battery 5 to power the 12V network.
• the balancing system may be larger and the balancing more powerful.
• the sizing of the components of the balancing system 3 is adapted for such a transfer of energy from the power battery 1 to the auxiliary battery 5.
• the balancing system of the third or fourth embodiment may also include a device 17 for monitoring the voltage across the stages 11 of accumulator (s) 9.
• This accumulator voltage monitoring device 17 (FIG. 10) comprises, for example, measurement means at the terminals of each stage 11, configured to transmit their measurement results to the control device 19.
• the control device 19 can control the switches 27 individually, so that the switch 27 associated with the most loaded stage 11 is controlled to be closed.
• the control device 19 may further comprise at least one processing means for receiving the voltage measurements of the monitoring device 17, analyzing the measured voltages, and controlling the closing of one or more switches 27 according to the analysis results. measured voltages.
• control device 19 may comprise a means for comparing the voltages measured between them and a means for determining the most loaded stages from the comparison results.
• control device 19 may comprise means for calculating a product P for each stage 11 according to the following formula (1):
• the capacity corresponds to the electric charge that can provide the battery and is usually expressed in Ah or mAh. This is an intrinsic characteristic for each accumulator. This value can evolve slowly depending on the temperature, aging, and decreases as the life of the battery. The information on the capacity of each stage 11 may be the result of learning during the different cycles.
• the reference capacity is usually given by the manufacturer, for example 60Ah.
• the control device 19 may further comprise means for determining the stage (s) 11 to be discharged so as to equalize the products P or F for each stage 11.
• the control device 19 may comprise according to yet another variant:
• control device 19 may further comprise at least one processing means for determining the power to be delivered by each stage 11 so as to supply the network 12V. II.3 Operation
• FIGS. 9 and 10 an example of operation of the balancing system 3 of the third embodiment, in the case of the charging of a power battery 1, is described so as to bring all the stages 11 at a nominal voltage level.
• This balancing can be done at the same time as the charge of the battery 1.
• This balancing can be done at any time of operation of the vehicle when a consumption is observed on the auxiliary battery 5 or it is possible to charge the auxiliary battery 5.
• the voltage of the accumulator reflects its state of charge. This is not always the case but it makes it easier to illustrate the subject.
• the state of charge differences can only be estimated from the voltage at the end of charging and / or discharging. Otherwise, the voltage differences between accumulators are often too small to be measured at a reasonable cost.
• each stage 11 has a respective voltage V1, V2, V3, V4.
• the threshold voltage being for example 3.6V.
• the measurement means at the terminals of the first stage 11 thus measures a voltage V1 of 3.3V
• the second and third measurement means respectively a voltage V2, V3 of 3.2V
• the fourth measurement means a voltage V4 of 3, 5V.
• This measurement can be done at any time of operation of the vehicle, at regular intervals, or at a predefined time such as the end of charge or a rest period of the vehicle.
• the control device 19 can compare in step E202 the measured voltages.
• the voltage V4 across the fourth stage 11 is greater than the voltage V1 across the first stage, itself higher than the respective voltages V2 and V3 of the second and third stages 11.
• the control device 19 can determine from this information, by comparing the voltages measured between them, the 11 most loaded stages.
• the voltage stage V4 is more charged than the voltage stage VI which is more charged than the voltage stages V2 and V3.
• the control device 19 therefore determines from this information that the most heavily loaded stages 11 are the fourth and the first stage 11, and then controls in step E203 the closing of the associated switches 27.
• the voltage across the secondary 25 is negative thereby blocking the diode 29.
• the energy of the associated stage 11 is therefore transferred via the transformer 21 the auxiliary battery 5.
• the charge of the accumulators 9 is then balanced by transferring the energy of the most charged stage 11 to the 12V network.
• each stage 11 discharges as a function of the state of charge of the stage 11, for example so as to equalize the products P for each stage 11 according to the following formula (1):
• the product P increases inversely with the state of charge; more a stage 11 is loaded plus the product P is small. Thus, priority is given to the stages 11 whose products P are the weakest.
• step E203 It is possible to calculate in step E203 a closing time of the switches 27 as a function of these products P. The smaller the product P, the more the stage is loaded, and the longer the closure time is, so as to discharge in priority the 11 most loaded stages.
• a charge rate can be determined for each stage and a suitable closing time can be deduced according to the determined charge rate.
• the charge rate can be determined with respect to a threshold voltage, for example 3.6V. According to the example given, we thus determine:
• Step E203 then calculates a closing time of the switches 27 as a function of these charge rates.
• the closing time of the switches 27 associated with the second and third stages 11 of voltage V2 and V3 will therefore be less than the closing time of the switch 27 associated with the first voltage stage VI, itself lower than the closing time of the switch 27 associated with the last stage 11 of voltage V4.
• stages 11 of respective voltages V4 and V1 are discharged so that they reach substantially the same level of charge of the stages
• Balancing can be done at the same time as the discharge of the battery 1.
• the 11 most loaded stages are used primarily to supply the low voltage network 12V.
• control device 19 can for example compare the products F for each stage 11 according to the following formula (2):
• the product F increases with the state of charge of each stage 11.
• the stages 11 whose products F are highest are firstly discharged.
• the most loaded stages 11 are determined by comparing the voltage levels measured similarly to the first variant of the charging phase.
• the stages 11 charged are determined by calculating a charge rate by comparison with a threshold voltage, similarly to the third variant of the charging phase.
• the control device 19 can further control the power delivered by each stage 11 to power the 12V network.
• these stages 11 will deliver a maximum power Pm, for example 20W.
• the energy transferred from the power battery 1 to the auxiliary battery 5 serves to balance the charge level of the battery stages 11 of the power battery 1.
• a single electronic can perform the two functions of load balancing accumulators 9 of the power battery 1 and auxiliary battery power 5.
• this redundancy of the converters 15 facilitates the removal of the auxiliary battery 3 because of the redundancy.
• the balancing system 3 can furthermore provide a function of supplying the 12 volts accessory to the vehicle when the converters 15 pass sufficient power.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)
• Secondary Cells (AREA)
• Dc-Dc Converters (AREA)

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• 2010
  • 2010-05-05 FR FR1053516A patent/FR2959885B1/fr not_active Expired - Fee Related
• 2011
  • 2011-03-09 FR FR1151924A patent/FR2959887B1/fr active Active
  • 2011-05-04 EP EP11718362A patent/EP2567443A2/de not_active Withdrawn
  • 2011-05-04 US US13/696,210 patent/US20130076310A1/en not_active Abandoned
  • 2011-05-04 WO PCT/EP2011/057165 patent/WO2011138381A2/fr not_active Ceased
  • 2011-05-04 CN CN2011800329085A patent/CN103069682A/zh active Pending
  • 2011-05-04 KR KR1020127031808A patent/KR20130073915A/ko not_active Withdrawn
  • 2011-05-04 JP JP2013508494A patent/JP2013530665A/ja active Pending

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