EP0966772A2 - Systeme de signalisation - Google Patents

Systeme de signalisation

Info

Publication number
EP0966772A2
EP0966772A2 EP98900924A EP98900924A EP0966772A2 EP 0966772 A2 EP0966772 A2 EP 0966772A2 EP 98900924 A EP98900924 A EP 98900924A EP 98900924 A EP98900924 A EP 98900924A EP 0966772 A2 EP0966772 A2 EP 0966772A2
Authority
EP
European Patent Office
Prior art keywords
battery
cell
signalling
signal
operable
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98900924A
Other languages
German (de)
English (en)
Inventor
Silviu The Innovation Centre Puchianu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Metrixx Ltd
Original Assignee
Metrixx Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB9701165.4A external-priority patent/GB9701165D0/en
Priority claimed from GB9717967A external-priority patent/GB2328540B/en
Priority claimed from GB9720037A external-priority patent/GB2321315A/en
Application filed by Metrixx Ltd filed Critical Metrixx Ltd
Publication of EP0966772A2 publication Critical patent/EP0966772A2/fr
Withdrawn legal-status Critical Current

Links

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
    • H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells 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
    • B60L58/21—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 having the same nominal voltage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G01R31/3828—Arrangements for monitoring battery or accumulator variables, e.g. SoC using current integration
    • G01R31/3832—Arrangements for monitoring battery or accumulator variables, e.g. SoC using current integration without measurement of battery voltage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
    • 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
    • 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
    • H02J7/0025—Sequential battery discharge in systems with a plurality of batteries
    • 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
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • 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
    • B60L2260/00—Operating Modes
    • B60L2260/40—Control modes
    • B60L2260/44—Control modes by parameter estimation
    • 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
    • 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
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/16—Information or communication technologies improving the operation of electric vehicles

Definitions

  • the present invention relates to a signalling system.
  • the invention is applicable for use in a system for monitoring and/or controlling the cells of an industrial battery.
  • Industrial batteries comprise a number of rechargeable battery cells which can be electrically connected in various series and series-parallel combinations to provide a rechargeable battery having a desired output voltage. To recharge the battery, a current is passed through the cells in the opposite direction of current flow when the cells are working.
  • battery cells There are many different types of battery cells available, but those most commonly used in industrial applications are lead acid battery cells, each of which provides 2 volts, and nickel-cadmium (Nicad) battery cells, each of which provides 1.2 volts.
  • the batteries are usually used as a back-up power supply for important systems in large industrial plants, such as off-shore oil rigs, power stations and the like. Since the batteries are provided as back-up in the event of a fault with the main generators , they must be constantly monitored and maintained so that they can provide power to the important systems for a preset minimum amount of time .
  • each cell monitoring device since the cells are connected in series and since each cell monitoring device is powered by the cell which it is monitoring, the ground or reference voltage of each cell monitoring device is different.
  • the negative terminal, i.e. the ground, of the fifth cell will be at a potential of approximately 8 volts and the positive terminal will be at a potential of approximately 10 volts
  • the negative terminal of the seventh cell will be at a potential of approximately 12 volts and the positive terminal will be at a potential of approximately 14 volts.
  • each cell is independently linked to its own electrically isolated input at the central monitoring system.
  • the problem with this system is that a large number of connectors are needed to link the individual cell monitoring devices to the central monitoring system. Consequently, in practice, it is seldom used for permanent real-time monitoring of the battery cells.
  • each cell monitoring device is serially linked to its neighbours in a daisy-chain configuration, either by using optical links between the monitoring devices or by using transformers which have no DC path.
  • the problem with this system is that to operate, each of the cell monitoring devices requires either an electrical to optical and an optical to electrical converter or a modulator and a demodulator, which makes them relatively expensive and inefficient since this additional circuitry requires more power from the cell.
  • the inventor has realised that it is possible to overcome the problem of having the cell monitoring devices operating at different voltages using simple electronic components and that therefore, there is no need for electrical isolation between the individual cell monitoring devices and the central monitoring system.
  • the present invention provides a signalling system for use with a plurality of series connected battery cells, comprising: a plurality of cell signalling devices, each to be powered by a respective one or more of the plurality of battery cells; and a communication link connecting the plurality of cell signalling devices in series; wherein each cell signalling device comprises a level shift circuit which is operable to receive signals transmitted from an adjacent cell signalling device to shift the level of the received signal and to output the level shifted signal for transmission to the communication link.
  • a level shift circuit in each cell signalling device the cell signalling devices can be linked together in a communication link without the need for electrical isolation between the signalling devices.
  • the signalling system can be used as part of a battery monitoring and/or control system which is used to monitor and/or control the series connected battery cells.
  • the signalling system obviates the need for electrical isolation between individual cell signalling devices. Consequently, the communication link can be a simple one-wire communication bus.
  • each of the cell signalling devices is able to receive communications from and transmit communications to the communication link so that they can communicate with, for example, the battery monitoring and/or control system.
  • each cell signalling device can comprise two DC level shift circuits, one for increasing the level of the received signals for transmission to a cell signalling device having a higher ground potential than that of the receiving cell signalling device, and one for reducing the level of the received signals for transmission to a cell signalling device which has a lower ground potential than that of the receiving cell signalling device.
  • Each level shift circuit can comprise a simple electronic device, such as a comparator, which consumes a relatively small amount of power from the battery cell which powers the cell signalling device.
  • the first aspect of the present invention also provides a cell signalling device for use in the above defined signalling system, comprising: a power input terminal connectable to the cell or cells which is or are to power the cell signalling device; and at least one DC level shift circuit for receiving signals from an adjacent cell signalling device, for shifting the level of the received signal, and for outputting the level shifted signal for transmission to the communication link.
  • the first aspect of the present invention also provides a signalling kit comprising a plurality of the cell signalling devices defined above.
  • the kit may also comprise the communication link for connecting the cell signalling devices in series.
  • the first aspect of the present invention also provides a signalling method using a plurality of series connected battery cells, comprising the- steps of: providing a plurality of cell signalling devices and powering them with a respective one or more of the plurality of battery cells; providing a communication link which connects the plurality of cell signalling devices in series; receiving signals transmitted from an adjacent cell signalling device; shifting the level of the received signals; and outputting the level shifted signals to the communication link.
  • Figure 1 schematically shows a battery comprising a number of battery cells connected in series, a central battery monitoring system for monitoring the condition of the battery as a whole and individual cell monitoring devices for monitoring the cells of the battery;
  • FIG. 2 is a schematic diagram showing more detail of the central battery monitoring system shown in Figure 1;
  • Figure 3 is a schematic diagram of one of the cell monitoring devices shown in Figure 1 ;
  • Figure 4 is a plot showing the battery-cell voltage distribution
  • Figure 5a is a circuit diagram of a first comparator forming part of the cell monitoring device shown in Figure 3;
  • Figure 5b is a circuit diagram of a second comparator forming part of the cell monitoring device shown in Figure 3;
  • Figure 5c is a schematic representation showing part of the battery-cell staircase voltage distribution and example data pulses which are applied to the input of the comparators shown in Figures 5a and 5b;
  • FIG. 6 is a schematic diagram of a battery cell monitoring device for use in a battery monitoring system according to a second embodiment of the present invention
  • Figure 7 schematically shows a battery comprising a number of battery cells connected in series, a central battery control system for controlling the battery as a whole and individual battery cell controllers for controlling the cells of the battery;
  • FIG 8 is a schematic diagram of one of the battery cell control devices shown in Figure 7;
  • FIG. 9 is a schematic diagram of a battery cell monitoring and control device for use in a battery monitoring and control system embodying the present invention.
  • Figure 10 is a schematic representation of an industrial battery in which the cells of the battery are connected in a series-parallel configuration
  • Figure 11 is a schematic diagram of a system for monitoring a plurality of industrial batteries.
  • FIG. 1 schematically shows an industrial battery, generally indicated by reference numeral 1, comprising a number of lead acid battery cells C C 2 , C 3 ... C n connected so that the negative terminal Ci " of cell C £ is connected to the positive terminal C i . 1 + of preceding cell C ⁇ and the positive terminal C £ + of cell Ci is connected to the negative terminal C 1+1 " of the succeeding cell C i+1 , whereby the negative terminal Cj " of the first cell C x is the negative terminal of the battery and the positive terminal C n + of the last cell C n is the positive terminal of the battery.
  • the battery cells are lead acid, they each provide approximately 2 volts and the voltage of the battery as a whole will be approximately 2n volts . For industrial applications a voltage of 120 volts is often required. Therefore, 60 series connected lead acid or 100. series connected Nicad battery cells would be required. Sometimes, each cell in the series connection is connected in parallel with one or more similar cells, so as to provide redundancy, so that the battery will not fail if a single cell fails.
  • FIG. 1 also shows a central battery monitoring system 3 which is powered by the battery 1 via connectors 4 and 6, which connect the central battery monitoring system 3 to the negative terminal Ci " and the positive terminal C n + of the battery 1, respectively.
  • the battery monitoring system 3 monitors the status of the industrial battery 1 as a whole, based on charging and discharging characteristics of the battery (determined by monitoring the battery voltage from connectors 4 and 6 and the current being drawn from or supplied to the battery 1, which is sensed by current sensor 8, whilst the battery is being charged and subsequently discharged), the ambient temperature (input from temperature sensor 5) and on information relating to the efficiency characteristics of the battery cells (provided by the battery cell manufacturer).
  • the monitoring results can be stored in the central battery monitoring- system 3 or they can be transmitted to a remote user (not shown) via the telephone line 7.
  • Each of the battery cells C L shown in Figure 1, also has a battery cell monitoring device CMi mounted on top of the cell between its positive and negative terminals Ci + and C " respectively, which monitors the status of the cell Ci-
  • the communication link 9 links the cell monitoring devices CMi i- n series in a daisy chain configuration to the central battery monitoring system 3, so that communications from the central battery monitoring system 3 to the cell monitoring devices CM pass from left to right along the communication link 9 and communications from the cell monitoring devices CM £ to the central battery monitoring system 3 pass from right to left along the communication link 9.
  • Each cell monitoring device CMi nas lts o n cell identification or address which, in this embodiment, is set in advance using DIP-switches mounted in the device. This allows communications from the central battery monitoring system 3 to be directed to a specific cell monitoring device and allows the central battery monitoring system 3 to be able to identify the source of received communications.
  • the battery monitoring system shown in Figure 1 operates in two modes.
  • the central battery monitoring system 3 monitors the condition of the industrial battery 1 as a whole and polls each of the cell monitoring devices CMi in turn.
  • each of the cell monitoring devices CM t listens to communications from the central battery monitoring system 3 on the communication link ' 9 and responds when it identifies a communication directed to it.
  • each cell monitoring device CM L performs a number of tests on the corresponding battery cell C t and returns the results of the tests back to the central battery monitoring system 3 via the communication link 9.
  • the central battery monitoring system 3 listens for communications on the communication link 9 from the cell monitoring devices CM L indicating that there is a faulty condition with one of the battery cells C t .
  • each cell monitoring device CM £ continuously monitors the corresponding battery cell Ci and, upon detection of a faulty condition, checks that the communication link 9 is free and then sends an appropriate message back to the central battery monitoring system 3 via the communication link 9.
  • FIG 2 is a schematic diagram of the central battery monitoring system 3 shown in Figure 1.
  • the central battery monitoring system 3 comprises a CPU 11 for controlling the operation of the central battery monitoring system 3.
  • the CPU 11 is connected, via data bus 12, to a main memory 13 where data from the input sensors is stored and where test programs are executed, to a display 15 which displays the battery's current status and to a mass storage unit 17 for storing the sensor data and the results of the battery tests .
  • the mass storage unit 17 can be fixed within the central battery monitoring system 3, but is preferably a floppy disk or a PCMIA memory card which can be withdrawn and input into an operator's personal computer for analysis.
  • An operator can also retrieve the stored data and results and control the set up and initialisation of the central battery monitoring system 3 ia the RS-232 serial interface 18.
  • the test results instead of storing the test results in the mass storage unit 17, they can be transmitted via a modem 21 and telephone line 7 to a remote computer system (not shown) for display and/or analysis .
  • the central battery monitoring system measures the total battery capacity in Amp-hours (Ahr) or Watt-hours (Whr), the actual or remaining battery capacity as a percentage of the total battery capacity and the internal resistance of the battery 1 as a whole.
  • the cental battery monitoring system 3 can also measure the internal resistance of the individual cells from the data received from the individual cell monitoring devices CM £ received via the communication link 9 and the communication circuit 19.
  • the central battery monitoring system 3 monitors how much charge is fed into the battery and how much charge is drawn from the battery.
  • the charging and discharging characteristics of the battery are not one hundred percent efficient. Therefore, the estimated capacity derived by monitoring the charge alone is not very accurate.
  • various factors affect the amount of charge which is input to or drawn from a battery during charging/discharging, including the ambient temperature, the magnitude of the charging/discharging current, the algorithm used for charging etc. Fortunately, many of these characteristics are known to the battery manufacturer and, in this embodiment the specific characteristics of the battery 1 are programmed into the central battery monitoring system 3. With this information, it is possible to determine more accurately how much charge has been stored in or withdrawn from the battery 1.
  • the battery 1 is charged with a charging current of 10 amps over a period of two hours at an ambient temperature of 20°C, and it is known that the efficiency characteristic of the battery is 95% for such a level of charging current and for that ambient temperature, then the total charge supplied to the battery is 19 Ahr .
  • I(t) current drawn from or supplied to the battery
  • CP capacity added to or removed from (depending on whether the current is negative or positive) the battery from time t 0 to time ti is given by:
  • the battery 1 In order to determine the initial total battery capacity (TCP), the battery 1 is initially fully charged by charging the battery for a long period of time using a small charging current. Then the battery 1 is discharged through a load (not shown) until the battery voltage drops below an end of discharge voltage limit (EODV) which is specified by the battery manufacturer. During this discharging period, the central battery monitoring system 3 monitors the discharge current via current sensor 8, and once the EODV limit is reached, it calculates the capacity (in Amp-hours) which has been removed from the battery using equation 1 above, with t 0 being the time that the discharge is initiated and time t j is the time that the EODV limit is reached. This capacity represents the total battery capacity (TCP).
  • EODV end of discharge voltage limit
  • the central battery monitoring system In this embodiment, the central battery monitoring system
  • RCP remaining battery capacity
  • TCP total battery capacity
  • RCP i t, ] RCP [ t Q ) + rc p ° ⁇ ( 2 )
  • CP [ t 0 , t x ] is calculated using equation 1 above.
  • the initial estimate for the remaining battery capacity is set equal to the total working capacity of the battery after the battery has been fully charged.
  • the battery is connected to two different loads and the central battery monitoring system 3 monitors the current through the loads from which it determines the internal resistance of the whole battery.
  • the central battery monitoring system 3 also monitors data received from the cell monitoring devices CMi via the communication circuit 19 and the communication link 9. If there is a fault with one of the battery cells Ci or if there is some other faulty condition, the CPU 11 can trigger a local alarm 23 to alert a technician that there is a fault with the battery 1 or with one or more of the battery cells Ci- In this embodiment, the conditions which define a fault and their thresholds are user definable and set in advance .
  • the central battery monitoring system 3 continuously monitors the battery 1, the sensor data and the other battery data, i.e. the remaining battery capacity etc, are only stored periodically in the mass storage unit 17 in order to save storage space.
  • the period is specified in advance by the user and in this embodiment is set at ten seconds.
  • the samples are stored, they are time and date stamped so that the battery charging and discharging behaviour can be monitored and used to detect the cause of an eventual battery failure.
  • the data which is to be stored is also filtered in order to try to identify and highlight important events, and the filtered data is also stored in the mass storage unit 17. What counts as an important event is user definable, but can be, for instance, a temperature increase of 2°C or a change in remaining battery capacity of greater than 1% of the total battery capacity.
  • the status data of the battery i.e. the battery voltage, the discharge/charge current, the battery temperature and the remaining and total battery capacities, are displayed on display 15.
  • the display 15 since the display 15 does not need to be continuously updated, it is only updated using the samples of the status data which are to be stored in mass storage unit 17. Therefore, in this embodiment, the display 15 is updated every ten seconds .
  • the central battery monitoring system 3 is also used to control the battery charger (not shown) which is used to charge the battery 1.
  • the central battery monitoring system 3 monitors the charging current, the remaining battery capacity, the ambient temperature etc and controls the operation of the charger (not shown) so that the battery charging is in accordance with the specific charging procedures recommended by the battery manufacturer for the battery 1.
  • the central battery monitoring system 3 is programmed to perform regular (for example daily or monthly) automated measurements of the total battery capacity and the battery internal resistance using the procedures outlined above. This allows the central battery monitoring system 3 to be able to build up a picture of the battery life characteristics and to be able to predict the battery end of life and the early detection of faulty conditions .
  • FIG. 3 is a schematic diagram showing, in more detail, one of the cell monitoring devices CMi.
  • cell monitoring device CMi comprises a microcontroller 31 for controlling the operation of the cell monitoring device CM an d for analysing sensor data received from voltage interconnection sensor 33, cell voltage sensor 35, temperature sensor 37 and electrolyte level/PH sensor 39.
  • the voltage interconnection sensor 33 measures the voltage drop between the cell 'being monitored and its neighbouring cells, by measuring the potential difference between each terminal of the cell C and the respective terminal connections which connects cell C t with its neighbouring cells. Ideally, there should be no voltage drop between each terminal and the corresponding terminal connection. However, due to chemical deposits accumulating at the cell terminals with time, or because of cell malfunction, a difference in potential between the cell terminals and the corresponding connectors sometimes exists, indicating that there is a fault, either with the battery cell Ci or with the interconnection with a neighbouring cell.
  • the cell voltage sensor 35 is provided for sensing the potential difference between the positive terminal C L + and the negative terminal Ci " of the cell C which it is monitoring.
  • the temperature sensor 37 senses the cell temperature locally at the cell Ci- By monitoring the local temperature at each cell C i r it is possible to identify quickly faulty cells or cells which are not operating efficiently.
  • the electrolyte level/PH sensor senses the electrolyte level and/or the electrolyte PH of the battery cell Ci which it is monitoring.
  • the microcontroller 31 analyses the data input from the sensors and monitors for faulty conditions and reports to the central battery monitoring system 3 via the communication link 9. Since the microcontroller 31 processes digital data, and since the signals received from the sensors and the messages received from the battery monitoring system 3 are analogue signals, the microcontroller 31 has a built-in analogue to digital convertor (not shown) so that it can convert the sensor data and the received messages into corresponding digital signals.
  • each cell monitoring device CMi Since the cell monitoring devices are connected in series by the communication link 9, each cell monitoring device CMi will either receive communications originating from the central battery monitoring system 3, from the left hand side of the communication link 9 for transmission to the next cell monitoring device CM i+1 , or they will receive communications from cell monitoring device CM i+1 from the right hand side of the communication link 9 for transmission back to the central battery monitoring system 3.
  • each cell monitoring device CM L has an uplink 41 for transmitting data received from cell monitoring device to cell monitoring device CM i+1 , and a down-link 43 for transmitting data received from cell monitoring device CM i+1 to cell monitoring device CMi_ ! .
  • the up-link 41 has a transceiver 45 for increasing the reference voltage of the data signal so that it can be received by the next cell monitoring device CM i+1
  • the down-link 43 has a transceiver 47 which reduces the reference voltage of the received data so that it can be received by the cell monitoring device CM ⁇ .
  • the up-link 41 and the down-link 43 are connected to the one wire communication link 9 via switches 49 and 51 which are controlled by microcontroller 31, as represented by arrows 52.
  • the way in which the microcontroller 31 controls the position of the switches 49 and 51 for the above described two modes of operation will be apparent to those skilled in the art and will not be described here.
  • the microcontroller 31 is connected to the up-link 41 by connection 53 so that it can listen for communications sent from the central battery monitoring system 3 which are directed to it. Similarly, the microcontroller 31 is connected to the down-link 43 by connection 55 so that the microcontroller 31 can send messages back to the central battery monitoring system 3, either upon being polled or upon detection of a fault.
  • the positive terminal Ci + and the negative terminal Ci " of cell Ci are connected to the input of a DC to DC convertor 57, which generates, relative to the ground or reference voltage V, ⁇ 1 of cell Ci (which equals the voltage potential of the negative terminal Ci " of cell C £ ) the voltages V R X ⁇ 5V, which are used to power the microcontroller 31 and the transceivers 45 and 47.
  • FIG 4 shows the voltage characteristic of the industrial battery showing each cell's terminal potential versus the cell's position in the series. As shown in Figure 4, this voltage characteristic has a staircase shape, with each stair having a height equal to the voltage V CELL of the respective battery cell C .
  • Each cell monitoring device CM t uses the fact that there is only a small difference between the reference voltages of adjacent cells and that therefore the transceivers 45 and 47 only have to increase or decrease the reference voltage of the received data by this voltage difference.
  • the transceivers 45 and 47 comprise voltage comparators and the messages transmitted to and from the central battery monitoring system 3 are encoded within the transitions of a square wave signal.
  • Figure 5a is a circuit diagram of a voltage comparator 61 forming part of the transceiver 45 provided in the uplink 41 shown in Figure 3. The limits of the comparator 61 are V RE + 5V and V REJ - 5V, which are generated by the DC to DC converter 57.
  • Figure 5b is a circuit diagram of a voltage comparator 63 forming part of the transceiver 47 provided in the down-link 43 shown in Figure 3. As with comparator 61, the limits of comparator 63 are V R X + 5V and V RE - 5V.
  • Figure 5c shows part of the battery-cell voltage distribution shown in Figure 4 and, superimposed thereon, data pulses for illustrating the way in which data is passed along the communication link 9.
  • the left-hand side of Figure 5c shows the ground or reference voltage Vr ⁇ 1"1 for cell C ⁇ and shows that data pulses 65 output by cell monitoring device CMi_, vary between V REF X_1 + 5V and V R X -1 - 5V.
  • the data pulses 65 will be transmitted from cell C ⁇ to cell Ci and will be applied to the positive input of the comparator 61 on the up-link 41 of cell monitoring device CMi via switch 49.
  • the received pulses are compared with V RE - 2V (which is an approximation of the reference voltage V REF 1_1 of the cell which generated the received pulses 65, since the cells are lead acid battery cells which provide approximately 2 volts each) and the data pulses 67 output by comparator 61 will correspond with the received data pulses 65 but will vary between V R ⁇ + 5V and V R ⁇ - 5V, as shown in the middle of Figure 5c. Therefore, the DC level of the square wave pulses has been increased by passing it through the comparator 61.
  • the output data pulses 67 are transmitted to the next cell monitoring device CM i+1 via switch 51 and communications link 9.
  • the data pulses 67 output from comparator 61 are also input to the microcontroller 31 via connection 53, so that the microcontroller 31 can identify whether or not the communication from the central battery monitoring system 3 is directed to it. If the communication is directed to it, the microcontroller 31 processes the request, performs the necessary tests and transmits the appropriate data back to the central battery monitoring system 3.
  • the received data pulses 69 are transmitted to cell monitoring device CM £ from cell monitoring device CM i+1 for transmitting back to the central battery monitoring system 3, the received data pulses 69, which vary between v REF iU + 5V and V RKF i+1 - 5V, are applied to the positive input of comparator 63 on the down-link 43 of cell monitoring device CM via switch 51. As shown in Figure 5b, the received pulses 69 are compared with V RE + 2V (which is an approximation of the reference voltage V REF i+1 of the cell C i l which generated the received pulses 69, since the cells are lead acid battery cells which provide approximately 2 volts each).
  • each of the cell monitoring devices CMi operate in a similar manner.
  • the first cell monitoring device CM L has the same ground or reference voltage as the central battery monitoring system 3. Therefore, it is not necessary to use a transceiver 45 in the up-link 41 of the first cell monitoring device CM , although one is usually used in order to buffer the received signals and in order to standardise each of the cell monitoring devices CMi.
  • the last cell monitoring device CMcorro will not receive data pulses from a subsequent cell monitoring device and therefore, does not need a transceiver 47 in its down-link.
  • the battery monitoring system described above has the following advantages:
  • each cell monitoring device CMi will only consume a few milli-amps and only requires very inexpensive and readily available DC to DC converters for converting the battery cell voltage to the supply voltage needed by the microcontroller 31 and the transceivers 45 and 47.
  • each cell monitoring device CM £ is linked to its neighbours by a simple wire. The cost of the battery monitoring system is therefore low and system installation is simplified.
  • each cell C £ can be determined in real-time and without having to disconnect the cell from the battery, since the central battery monitoring system 3 is capable of measuring battery charging and discharging current (which is the same as the cell current) and can correlate it with individual cell voltages (determined by the cell monitoring devices) in order to calculate each cell's internal resistance.
  • Each cell monitoring device CM ⁇ is able to measure the voltage drop on cell to cell interconnections and indicate a faulty interconnection condition, usually due to chemical deposits accumulating at the cell terminals with time or because of cell malfunction.
  • each cell monitoring device CM £ is able to measure the cell voltage and the cell temperature, it is possible to increase the probability of detecting a faulty cell. Therefore, the industrial battery need only be serviced when required.
  • each cell monitoring device CM t can read the corresponding cell voltage, cell temperature etc at the same time as the other cell monitoring devices, the data produced by each cell monitoring device is less likely to be corrupted by changes in load and/or changes in ambient temperature which occur with time, as compared with prior art systems which take readings from the individual cells one at a time.
  • each cell monitoring device CM L has a microcontroller 31 for receiving messages from the central battery monitoring system 3, for analysing data from various sensors and for sending data back to the central battery monitoring system 3 via the communication link 9.
  • Figure 6 schematically shows an alternative cell monitoring device CMi of a second embodiment which does not use a microcontroller 31.
  • each cell monitoring device CM j comprises a signal generator 71 which receives sensor signals from the cell voltage sensor 35 and the temperature sensor 37 and outputs, on line 73, a signal which varies in dependence upon the received sensor signals.
  • the signal generator 71 may comprise a voltage controlled oscillator which outputs an alternating signal whose frequency varies in dependence upon an input voltage from, for example, the cell voltage sensor 35.
  • each cell monitoring device CMi only transmits signals back to the central battery monitoring system 3, they can not receive messages from the central battery monitoring system. Therefore, only a down-link is required to receive signals at input terminal 77, transmitted from cell monitoring device CM i+1 .
  • each cell monitoring device CM is powered by the cell Ci which it is monitoring. This is illustrated in Figure 6 by the connections C £ + and C " which are connected to input terminals 74 and 76 respectively. Since the communication link 9 connects each of the cell monitoring devices CM £ in series in a daisy chain configuration, cell monitoring device CM t will receive signals, at input terminal 77, from cell monitoring device CM i+1 . The received signals are applied to a DC level shift circuit 79 which reduces the DC level of the received signals and supplies them to the output terminal 75 for transmission to the next cell monitoring device CMi_ ⁇ in the communication link 9.
  • FIG. 7 schematically shows a third embodiment which is a control system for controlling the cells of an industrial battery.
  • the control system has a similar architecture to the battery monitoring system shown in Figure 1 , except that the central battery monitoring system 3 is now a central battery control system 80 and the cell monitoring devices CM t are now battery cell control devices CCi.
  • the central battery control system 80 communicates with each of the cell controlling devices CCi via tne communication link 9.
  • FIG 8 schematically shows one of the battery cell control devices CC shown in Figure 7.
  • Each cell controlling device CC £ is used to control the topping up of acid and water in the respective battery cell Ci, in response to an appropriate control signal received from the central battery control system 80.
  • each cell control device CCi is powered by the cell which it is to control, as represented by inputs C + and C " applied to input power terminals 81 and 85 respectively.
  • each cell controlling device CCi is arranged to receive messages from the central battery controlling system (not shown), but not to transmit messages back.
  • signals received at the input terminal 85 from cell controller CC ⁇ are applied to DC level shift circuit 87, which increases the DC level of the received signals and outputs them to output terminal 89 for transmission to the next cell controlling device CC i+1 .
  • the microcontroller 91 monitors the received signals via connection 93 and outputs appropriate control signals to output terminals 95 and 97 when the received signals are directed to it.
  • the control signals output to terminals 95 and 97 are used to control the position of valves 99 and 101 respectively, so as to control the amount of water and acid to be added to the battery cell Ci from the water tank 103 and the acid tank 105.
  • the microcontroller 91 determines the amount of water and acid to add with reference to the sensor signals received from the electrolyte level/PH sensor 39.
  • FIG. 9 schematically shows a cell monitoring and control device CM&C which can be used in a combined battery control and monitoring system in which there is no central battery monitoring and control system and in which each cell monitoring and control device CM&C communicates directly with the other cell monitoring and control devices.
  • each cell monitoring and control device CM&C s powered by the cell which it is monitoring and controlling, as represented by inputs C ⁇ and Ci " applied to input power terminals 115 and 117 respectively.
  • each cell monitoring and control device CM&Ci comprises a microcontroller 111 which receives sensor data from temperature sensor 37 and which outputs control data to output terminal 113 for controlling, for example, a liquid crystal display (not shown) mounted on the respective cell C .
  • the communication link comprises two wires 9a and 9b and therefore, switches 49 and 51 are not required to connect the up-link and the down-link to the communication link 9.
  • Wire 9a is used for passing communications up the series communication link 9 from cell monitoring and control device CM&Ci to cell monitoring and control device CM&C i+1 and wire 9b is used for transmitting signals down the series communication link 9 from cell monitoring and control device CM&Ci to cell monitoring and control device CM&Ci_, .
  • the signals received by cell monitoring and control device CM&Ci at input terminal 119 are applied to DC level shift circuit 121 which increases the DC level of the received signals and outputs them to output terminal 123 for transmission to cell monitoring and control device CM&C i+1 .
  • microcontroller 111 can receive data from and transmit data to both the up-link 9a and the down-link 9b via connections 131 and 133 respectively.
  • the transceivers 45 and 47 used in the up-link and the down-link within each cell monitoring device CM ⁇ comprises a voltage comparator.
  • Other types of transceivers could be used.
  • voltage to current and current to voltage comparators could be used.
  • the voltage to current comparators and the current to voltage comparators would be arranged alternatively along the communication link 9 so that a voltage to current comparator is connected to the input of a current to voltage comparator, and vice-versa.
  • comparators instead of comparators in order to raise or lower the reference voltage of the data being transmitted between cells, such as solid state analogue switches and current loops etc.
  • the data transmitted between cells and between the first cell and the central battery monitoring systems varies between V RE ⁇ 5V.
  • the value of 5 volts was chosen for convenience since the normal operating voltage for the microcontroller 31 is 5 volts above the ground voltage for that cell.
  • X must be greater than half the cell voltage V CELL in order for the comparator to be able to regenerate the received data pulses at the increased or decreased potential.
  • X should be at least two and a half times the cell voltage V CELL .
  • each cell monitoring device CM t could be used to monitor two or three series connected battery cells Ci .
  • X should be at least two and a half times the difference in the reference potentials between adjacent cell monitoring devices.
  • the received data pulses are compared with an approximation of the ground or reference voltage of the cell which sent the data pulses.
  • the received data pulses could simply be compared with the reference voltage of the cell monitoring device which receives the data pulses .
  • the cells are connected in series. It is possible to connect the battery cells C £ in a series-parallel or ladder configuration.
  • a single cell monitoring device CM is provided for monitoring each of the battery cells and the communication link 9 connects CM ia to CM ib and CM ib to CM i+la etc.
  • a single cell monitoring device could be used to monitor each parallel combination of battery cells C ia and C lb .
  • more than two battery cells can be connected in parallel.
  • the central battery monitoring and/or control system was provided at the zero volt reference voltage end of the communication link 9.
  • the central battery monitoring and/or control system could be connected at the high reference voltage end of the communication link 9.
  • the central battery monitoring and/or control system could be connected at both ends, thereby forming a circular communications path in which messages which are transmitted to and received from the battery monitoring/controlling system are passed in one direction through the cell monitoring/controlling devices. Therefore, each cell monitoring/controlling device only needs either an up-link or a down-link for increasing or decreasing the DC level of the received signals, depending on whether the messages are transmitted up or down the communication staircase.
  • the communication link 9 comprised either one or two wires .
  • the communication link 9 may comprise any number of wires along which data can be transmitted in parallel.
  • a separate central battery monitoring system or a central battery control system was provided.
  • a combined battery monitoring and control system could be used to both monitor and control the battery.
  • a single battery comprising a plurality of battery cells, is monitored and/or controlled by a central battery monitoring and/or controlling system.
  • Figure 11 shows an alternative embodiment where a plurality of batteries Bi are provided, and wherein each battery Bi is monitored by its own central battery monitoring system BMi which communicates with a remote operator's terminal 151 via a data bus 153.
  • the data bus 153 may be a proprietary data link or can be the public telephone exchange.
  • each of the central battery monitoring systems BM £ monitors the respective battery Bi and reports its status back to the remote operator's terminal 151, where the condition of each of the batteries is monitored by a human operator.
  • a similar system could also be provided for controlling or for monitoring and controlling a plurality of batteries.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)
  • Saccharide Compounds (AREA)
  • Remote Monitoring And Control Of Power-Distribution Networks (AREA)

Abstract

La présente invention concerne un système de signalisation de batterie permettant de contrôler et/ou commander une batterie (1) constituée de plusieurs éléments (Ci) montés en série. Lorsqu'on l'utilise pour contrôler les éléments de la batterie, ce système de signalisation peut comporter, d'une part un système central (3) de contrôle de la batterie permettant de contrôler la batterie (1) industrielle dans son ensemble, d'autre part un certain nombre de dispositifs (CMi) de contrôle des éléments permettant de contrôler un ou plusieurs éléments (Ci) et enfin une liaison de communication (9) permettant de monter en série les dispositifs de contrôle des éléments (CMi) sur le système central (3) de contrôle de la batterie. Lorsqu'il fonctionne, ce système (3) peut examiner à tour de rôle chacun des dispositifs de contrôle des éléments (CMi) et analyser les données reçues d'un dispositif de contrôle des éléments (CMi) dans lequel on a recherché les défauts de fonctionnement et/ou les éléments à faible rendement.
EP98900924A 1997-01-21 1998-01-20 Systeme de signalisation Withdrawn EP0966772A2 (fr)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
GBGB9701165.4A GB9701165D0 (en) 1997-01-21 1997-01-21 Battery life determination using an intelligent battery-life monitor circuit
GB9701165 1997-01-21
GB9717967A GB2328540B (en) 1997-08-22 1997-08-22 Signalling system
GB9717967 1997-08-22
GB9720037A GB2321315A (en) 1997-01-21 1997-09-19 Estimating total working capacity of a battery
GB9720037 1997-09-19
PCT/GB1998/000170 WO1998032181A2 (fr) 1997-01-21 1998-01-20 Systeme de signalisation

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EP0966772A2 true EP0966772A2 (fr) 1999-12-29

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EP98900924A Withdrawn EP0966772A2 (fr) 1997-01-21 1998-01-20 Systeme de signalisation

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AU (1) AU738680B2 (fr)
WO (1) WO1998032181A2 (fr)

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GB2350686B (en) 1999-06-03 2004-01-07 Switchtec Power Systems Ltd Battery capacity measurement
US6411912B1 (en) * 1999-07-09 2002-06-25 Alcatel Voltage level bus translator and safety interlock system for battery modules
AU2001290370A1 (en) * 2000-09-04 2002-03-22 Invensys Energy Systems (Nz) Limited Battery monitoring network
GB2413224B (en) 2001-05-14 2005-12-07 Eaton Power Quality Ltd Battery charge management
JP4605952B2 (ja) 2001-08-29 2011-01-05 株式会社日立製作所 蓄電装置及びその制御方法
US7199557B2 (en) 2003-07-01 2007-04-03 Eaton Power Quality Company Apparatus, methods and computer program products for estimation of battery reserve life using adaptively modified state of health indicator-based reserve life models
CN2906637Y (zh) * 2006-01-25 2007-05-30 江显灿 一种电动自行车的电池电量检测装置
US9270133B2 (en) 2007-04-02 2016-02-23 Linear Technology Corporation Monitoring cells in energy storage system
DE102007038532A1 (de) * 2007-08-16 2009-02-19 Robert Bosch Gmbh Akku- bzw. Batteriepack
JP5700756B2 (ja) * 2010-04-28 2015-04-15 矢崎総業株式会社 複数組電池の電圧測定装置
CN109278589B (zh) * 2018-11-28 2021-10-22 四川化工职业技术学院 基于pic单片机的双向主动均衡电动汽车电池监控系统及控制方法

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AU738680B2 (en) 2001-09-27
AU5672998A (en) 1998-08-07
WO1998032181A3 (fr) 1998-11-05
WO1998032181A2 (fr) 1998-07-23

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