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
• • 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
  • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
  • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
  • B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
  • B60L58/22—Balancing the charge of battery modules
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
  • H02J7/0014—Circuits for equalisation of charge between batteries
  • H02J7/0016—Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
  • H02J7/00302—Overcharge protection
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
  • H02J7/00309—Overheat or overtemperature protection
• • 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
  • B60L2250/00—Driver interactions
  • B60L2250/10—Driver interactions by alarm
• • 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
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using 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
  • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

• the present invention relates to a method and a device for dynamic monitoring and balancing of a pack of accumulator batteries.
• a battery is often called a pack, a term that actually covers a set of batteries.
• the "traction battery” contains a few dozen batteries. These batteries all have dispersions of characteristics which very significantly affect the value of their maximum capacity, their charge, discharge and aging dynamics.
• the after-sales service of the battery manufacturer must dynamically test the voltage variation of each battery for a given consumption.
• the voltage across an open circuit battery is in no way characteristic of its state. This operation practically results in the disconnection of each battery from the traction pack, which is long, expensive, painful and puts a brake on the development of electric vehicles.
• the subject of the present invention is a method for monitoring the state of all the individual batteries of a pack comprising several such batteries, which makes it possible not only to detect at any time in charge mode and in discharge mode batteries whose capacity is significantly different from that of the average pack, but also to correct the effects of this dispersion of characteristics without having to systematically replace the batteries of lower capacity (dynamic balancing), this process having to identify the batteries of more capacity low, and to warn the user when the battery capacity drops below a determined threshold.
• the present invention also relates to a device for implementing this method, a device which is inexpensive, simple to use and reliable.
• the process according to the invention is characterized by the fact that the voltage at the terminals of each battery and its temperature are monitored, that at charging mode of the battery pack at least part of the charging current is derived from each of the batteries to dissipate it outside the battery when the voltage at its terminals and / or its temperature indicates a state or risk of overcharging, and that under charging and discharging conditions the voltage evolution is monitored at terminals of each battery and its temperature, to detect any imbalance between the different batteries in the pack, record it and / or trigger an alarm.
• the monitoring and balancing device comprises, at the terminals of each individual battery, a sensor current in series with an energy dissipating ballast, the sensor being connected to a comparator receiving a set value, the output of the comparator controlling the ballast.
• FIG. 1 is a block diagram of a monitoring and balancing device according to the invention.
• FIG. 2 is a block diagram of one of the dynamic balancing modules of the device of Figure 1;
• FIG. 3 is a block diagram of one of the monitoring and balancing modules of the device in FIG. 1, and
• FIGS. 4 and 5 are examples of voltage diagrams at the terminals of two individual batteries having aged differently, for different discharge currents.
• battery means a box containing several elements, not accessible to the user (the voltage at the terminals of each element being approximately 2v for lead batteries), and comprising two terminals output (+ and -). The nominal voltage at these terminals is generally 6, 12v or 24v.
• a pack consists of several such batteries, generally connected in series. In the case of application to the electric traction of a vehicle, this pack may include several tens of batteries.
• the pack 1 comprising n batteries in series referenced B1 to Bn. At the terminals of each battery, an electronic monitoring and balancing device is connected, these electronic devices being respectively referenced 2.1 to 2.n.
• Each electronic device 2.1 to 2.n comprises a dynamic balancing module, these modules being respectively referenced 5.1 to 5.n, and a module for monitoring and balancing, these modules being respectively referenced 6.1 to 6.n.
• FIG 2 there is shown the block diagram of one of the dynamic balancing modules, referenced 5.i, all these modules being identical.
• the module 5.i is connected to the terminals of the corresponding battery Bi
• This module 5.i essentially comprises a ballast 7.i in series with a current sensor 8.i, this series circuit being ' directly connected to the terminals of the battery Bi
• the ballast 7.i is a device making it possible to derive, when necessary, all or part of the current I arriving at the battery Bi
• This derivative current is referenced i. Its value can therefore range from 0 to I.
• the battery Bi is therefore crossed by a current equal to Ii.
• the ballast 7.i must be capable of dissipating this current i, and is advantageously provided with an appropriate radiator.
• the ballast 7.i is a power transistor whose characteristics are appropriate to the current to be derived, the voltage across its terminals and the power to be dissipated.
• the dynamic balancing module (and therefore its power transistor) can be controlled in all or nothing (by a rectangular voltage, produced in a manner known per se, at variable frequency and / or duty cycle) or gradually by the module 6.i monitoring, the 5.i module automatically limiting the current to a value compatible with its heat dissipation capacity. Any other device making it possible to dissipate the variable current i may be suitable.
• the current sensor 8.i is of any suitable type.
• the output of this sensor 8.i is connected to an input of a comparator 9.i the other input of which is connected to the setpoint output of the corresponding module 6.i (described below with reference to the figure 3).
• the output of the comparator 9.i is connected to a device 10.i which controls the ballast 7.i in the manner specified above, as a function of the difference between said set value and the value measured by the sensor 8. i .
• the module 5.i comprises a safety device 11.i, in series with the ballast 7.i and the sensor 8.i, and which is connected to an input of the comparator 9.i.
• This device 11.i protects the battery Bi from a short circuit of the ballast 7.i, limits the current i to a maximum value compatible with the dissipation capacity of the ballast 7.i and prohibits the reverse flow of current through the ballast 7.i and sensor 8.i (that is to say the current in the opposite direction to that of current i).
• the module 6.i shown in FIG. 3 essentially comprises a microcontroller 12.i (or similar device) connected, on the input side, to a device 13.i for measuring the voltage across the terminals of the corresponding battery Bi, and to a device 14 .i for measuring the temperature of the battery (temperature of its housing, of one of its two terminals, or, preferably, when possible, of its electrolyte or of its plates).
• An output of the microcontroller 12.i is connected to a digital / analog converter 15.i supplying said setpoint value to the comparator 9.L
• This converter 15.i can be replaced by any device capable of producing this setpoint.
• the microcontroller 12.i is connected to a read-only memory 16.i (for example an EEPROM) which contains a conversion table, that is to say the data specific to the sensors 13.i and 14. i used, and used to convert the values they provide into "true" values.
• a calibration of these sensors is thus carried out in order to take account of their dispersions of characteristics and inaccuracies. Consequently, it is possible to use as sensors models which are imprecise (but faithful) and therefore inexpensive.
• the memory 16.i can also contain other information such as the serial number of the battery.
• An output of the microcontroller 12.i is connected via a device 16.i of galvanic isolation to the transmission line 3.
• This device 16.i is for example an opto-coupler or a pulse transformer. This galvanic isolation is necessary because the different batteries are at different floating potentials, the highest resulting from the sum of the voltages across the terminals of the different batteries in the pack.
• the microcontroller 12.i is also connected by a set 17.i of several wires to a binary coding device 18.i, connected on the other hand to a wire 19.i, itself connected to the negative pole of the battery Bi (as a variant, wire 19.i is connected to the positive pole of the battery).
• This coding device makes it possible, when the batteries are installed in the vehicle, to assign an "identity" (logical address) to each of the batteries, and therefore allows the controller 4 to recognize each of the batteries in the pack individually.
• the device 18.i can be produced in any other suitable way.
• the device in FIG. 3 also includes a regulated power supply device 21.1 connected to the terminals of the battery B.i and supplying the various circuits of this device 6. i.
• the device described above operates in the following manner.
• the controller 4 sends, periodically for example, via line 3, to all the modules 6.1 to 6.n, an order to measure the voltage across the terminals of the corresponding battery, and the temperature of this battery.
• the responses from modules 6.1 to 6.n reach the controller 4 in dispersed order, depending on the response and communication times for each of these modules. These responses include the requested measured values, accompanied by the address of the corresponding battery (supplied by the corresponding encoder 18).
• the controller 4 when it notices this faster increase, orders the corresponding modules 6.i to send, via their converter 15.i, a different set value, which has the effect of making the ballast 7.i pass corresponding (this ballast being, in general, normally closed when the capacity of the corresponding battery has the correct value).
• This ballast then derives part (i) of the current I, which makes it possible not to overcharge the lower capacity battery, while charging the higher capacity batteries at a higher value.
• one battery in the pack has a capacity of 150 Ah, while all the others have a capacity of 160 A. h.
• the charging time of these other batteries is 10h, and that all the batteries are completely discharged before charging.
• the controller 4 stores the capacities of the different batteries (or values proportional to these capacities), and can for example signal to the user too rapid decreases and / or decreases below a certain threshold of these capabilities. The user can then easily identify the faulty batteries, and replace them if necessary. As stated above, the controller 4 monitors the temperature of the batteries in the pack, this measurement being used on the one hand to corroborate the voltage measurement, and on the other hand to detect operating anomalies of the batteries leading to their excessive heating.
• FIGS. 4 and 5 show, by way of example, the curves giving the voltage across the terminals of a battery as a function of its capacity, during its discharge.
• the two figures relate to a battery with a nominal capacity of 160 Ah and a nominal voltage of 6 V.
• the curves in these figures have been established for different values of constant discharge current (25, 50, 100, 200 and 300 A).
• FIG. 4 relates to a battery that has aged more than that of FIG. 5. It can be seen that for the same discharge current, the voltage across the terminals of the battery in FIG. 5 drops faster than that of the battery in FIG. 5 and the residual capacity of the battery of FIG. 4 is lower than that of the battery of FIG. 5.

Applications Claiming Priority (3)

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• 1993
  • 1993-11-23 FR FR9313987A patent/FR2713019B1/fr not_active Expired - Fee Related
• 1994
  • 1994-11-18 CA CA002152929A patent/CA2152929A1/fr not_active Abandoned
  • 1994-11-18 WO PCT/FR1994/001351 patent/WO1995015023A1/fr not_active Application Discontinuation
  • 1994-11-18 EP EP95901505A patent/EP0680668A1/de not_active Ceased
  • 1994-11-18 US US08/481,511 patent/US5644209A/en not_active Expired - Fee Related
  • 1994-11-18 JP JP7514871A patent/JPH08506477A/ja active Pending

Non-Patent Citations (1)

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