GB2481670A - A battery management system for an electric vehicle - Google Patents

A battery management system for an electric vehicle Download PDF

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Publication number
GB2481670A
GB2481670A GB1106638.8A GB201106638A GB2481670A GB 2481670 A GB2481670 A GB 2481670A GB 201106638 A GB201106638 A GB 201106638A GB 2481670 A GB2481670 A GB 2481670A
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United Kingdom
Prior art keywords
battery
management system
battery management
traction
cell
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Application number
GB1106638.8A
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GB2481670B (en
GB201106638D0 (en
Inventor
Mark Robert Parr
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ELECTRIC VEHICLE Co Ltd
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ELECTRIC VEHICLE Co Ltd
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Classifications

    • 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
    • B60L1/00—Supplying electric power to auxiliary equipment of vehicles
    • B60L1/02—Supplying electric power to auxiliary equipment of vehicles to electric heating circuits
    • B60L1/04—Supplying electric power to auxiliary equipment of vehicles to electric heating circuits fed by the power supply line
    • 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
    • B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
    • B60L11/18—
    • B60L11/1809—
    • B60L11/1859—
    • B60L11/1861—
    • B60L11/1866—
    • 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
    • B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
    • B60L50/60—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries
    • B60L50/64—Constructional details of batteries specially adapted for electric vehicles
    • 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
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • 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
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to 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
    • 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
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
    • B60L58/14—Preventing excessive discharging
    • 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
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
    • B60L58/15—Preventing overcharging
    • 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
    • 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
    • B60L58/24—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries
    • B60L58/26—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries by cooling
    • 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
    • H02J7/0052—
    • 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
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
    • 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
    • Y02T90/14—Plug-in electric vehicles

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

The vehicle includes: (a) a traction battery comprising multiple individual cells, and (b) a secondary battery providing power for non-traction electric systems in the vehicle. The battery management system enables the secondary battery to be used to provide charge to individual cells in the traction battery. Non-traction electric systems include one or more of: electric heater, brake lights during regeneration, reverse lights, reverse warning horn, 12v vehicle charging unit, power steering pump output.

Description

I
ELECTRIC VEHICLE BATTERY MANAGEMENT SYSTEM
BACKGROUND OF THE INVENTION
S
I. Field of the Invention
The field of the invention is a battery management system for an electric vehicle, for example an electric vehicle that uses lithium-ion battery packs for traction.
tO 2. Technical background
Electric vehicles typically use Li-ion battery packs, made up of large numbers of individual li-ion battery cells. Li-ion celis are attractive for electric vehicle traction/propulsion because of their high power-to-weight ratio, far exceeding that of conventional lead-acid batteries. However, Li-ion cells require individual charge IS control and management: Li-ion cells are highly sensitive to both over-charging and over-discharging; if the voltage of an individual (and costly) cell falls below approximately 2.5V, it can be permanently damaged.
This situation is made more complex because there are manufacturing tolerances in each cell, meaning that capacity and impedance vary from cell to cell. Cells also behave differently depending on there position in the battery pack. Noticeably, cells positioned at either end of a series connected string suffer more charge depletion than those positioned in the centre of the pack. When bulk charging a series connected pack of for instance 32 cells, there will be some cells that arrive at the fully charged threshold whilst other cell will only be 9ft/o charged.
3. Description of the Prior Art
As noted above, you cannot discharge lithium-ion cell below 2.5v or they will be damaged. In a conventional battery management system, as soon as a single cell in a battery pack (which can be made up of 32 or more individual Li-ion cells) approaches this 2.5V threshold, the battery management system places the vehicle into a low speed, emergency' mode. Once the weakest cell is even closer to the 2.SV threshold, then no further power is drawn from the entire battery pack at all to ensure that no damage is done. But in practice, although you have to stop taking energy from the entire pack because the lowest cell has reached its minimum threshold, there could still be perhaps 20% charge remaining in the pack, overall. The range of the vehicle is less than it could be because of this approach to battery power management. On the next cycle, S the situation only gets worse as the lowest cell will again not attain full charge and again will be the first cell to force the discharge cycle to have to stop prematurely; vehicle range is hence less than it could or indeed should be.
The situation only gets \vorst with age. Stronger cells dominate the pack and the weak ones keep terminating the discharge cycle prematurely.
Sophisticated charge control and load balancing systems have been proposed to address these problems, but they are cosdy and unrellable and frequently require additional costly components; for electric vehicles to become a mass-market solution, then there remains a need for a low-cost, robust solution.
SUMMARY OF THE INVENTION
A battery management system for an electric vehicle is disclosed. The vehicle includes (a) a traction battery comprising multiple individual cells and (b) a secondary battery S providing power for non-traction electric systems in the vehicle. The battery management system enables the secondary battery to be used to provide charge to individual cells in the traction battery. Non-traction electric systems include one or more of: electric heater, brake lights during regeneration, reverse lights, reverse warning horn, l2v vehicle charging unit, power steering pump output.
Implementation features include the following: The secondary battery is typically a lead-acid battery or Li-ion battery; the individual cells in the traction battery are typically Li-ion cells.
IS
The battery management system is operable to enable the secondary battery to support weakening cells in the traction battery that are approaching a voltage threshold, taking them up from that voltage threshold. Specifically, during discharge, the battery management system monitors cells for voltage at a specific current draw and the battery management system then causes the weakest cell to be topped up for a pre-determined time using the secondary battery. The threshold is a threshold below which the cells would suffer damage, and is approximately 2.5V for a Li-ion cell. By providing charge to these weakening cells, the battery management system enables the secondary battery to support any and all cells during the discharge until all cells in the traction battery are balanced at their lowest, safe threshold, hence avoiding the problem of prematurely restricting or terminating discharge from the entire battery.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a schematic overview of the invention implemented in a vehicle.
Figure 2 shows an example of an implementation of the invention.
Figure 3A-3B show a circuit diagram for one implementation of the invention.
S Figure 4 shows a schematic overview of one implementation of the invention.
Figure 5 shows different charge stages for one implementation of the invention.
Figures 6-10 show an example of a rotor implementing one aspect of the invention.
DETAILED DESCRIPTION
The invention relates to a method for battery management system in an electric vehicle.
Although we will describe a battery management system for a Li-ion traction battery system, the basic principles may be applicable to other kinds of rechargeable battery.
The typical Li-ion vehicle traction battery pack includes individual cells series connected in a pack. The invention is at the cutting edge of modern U-ion battery pack management systems and has the ability to handle even poorly matched series connected celis. It can charge and discharge (at high current) any individual cell, at any time during bulk charge, thus fully charging all cells.
It also has the ability to support any individual low ccli during driving, thus extending the range of the vehicle markedly. Specifically, the battery (e.g. lead-acid or U-ion) conventionally used in an electric vehicle for providing power for non-traction electric systems (e.g. for power steering and for lights) is used to support those weakening cells in the traction battery that are approaching the 2.SV threshold; by providing charge to these cells, we avoid the problem of prematurely restricting or terminating discharge from the entire battery. This significantly improves vehicle range.
The invention has been tested in one embodiment on a battery pack with a defective cell loaded into the pack and this system has proved to support the defective cell in both charge and discharging whilst driving.
One embodiment of the method is schematically described in Figure 1 where the four main units are presented: * Traction drive unit * Charging module * Vehicle interface module Battery management system (BMS) module Figure 2 shows three of the units (Charging module, Vehicle interface module and Battery management system (BMS) module) when installed in a car.
The system is totally modular, comprising individual waterproofed units in the embodiment shown in Figure 2.
S One implementation of the invention utill2es a switching matrix that allows access to any cell to charge or discharge at any time.
For consistency and rellability of the system one embodiment of the invention utilises a system where it is imposable for any two cells to be shorted out. One embodiment of this system is shown in Figures 6 to 10, where an electro-mechanical device called a rotor' can charge or discharge any cell at anytime without fear of shorting two nodes or cell terminals.
In one embodiment, the invention has a full real-time current sensing system, thus giving the operator accurate battery state indication, including any ancillary drains such as, electric heater, and all other vehicle usage. Active opportunity charge also indicates battery top up in real time.
Battery management The preferred implementation uses a twin battery pack system: (a) the main traction battery and (b) the secondary battery that services the car's normal requirements (electric heater, brake lights during regeneration, reverse lights, reverse warning horn, 12v vehicle charging unit, power steering pump output etc.). This secondary battery is used to supply energy to individual (weakening) traction cells as required during traction pack discharge, taking them up from the dangerous 2.SV threshold. This has the effect of supporting any and all cells during the discharge until all traction cells are balanced at their lowest, safe threshold, at which point we have a true, even discharge of the maximum safe extent from the Li-ion traction battery pack -greatiy increasing range. Using the secondary battery in this way is a cheap and effective approach since it has to be present in the vehicle anyway and is readily able to provide appropriate levels of charge to weakening celis in the traction battery.
One aspect of the invention is schematically described in Figure 4 where during charge two AC chargers are used. The main Bulk charger is a high efficiency 240V AC charger that is applied to the traction battery and is throttled by the charge computer and the secondary 240V AC charger is applied to individual cells that are lagging in bulk charge. This is supplied via the rotor and has the effect of all cells being balanced and fully charged.
There are three distinct charging phases, as shown in Figure 5.
Phase one, bulk charge with reference to Figure 5. Full power is applied by the Bulk charger to the traction pack; the secondary charger is providing supplemental charging to lagging cells via the mechanical rotor (described in detail later).
Phase two, with reference to Figure 5. When the highest cell (i.e. cell with the highest voltage) reaches a predefined voltage level, for example 3.45v, the main charger is throttled back, for example to 15 Amps and the rotor now bleeds charge off the highest cell to again balance the pack.
Phase three, with reference to Figure 5. The Bulk charger throttles to maintain cells at a predefined voltage level, for example 4.2v and the secondary charger sequences through the whole pack, cell by cell, charging or discharging as required to maintain the pack in a full state.
Once the pack has been fully charged, it is maintained in phase three until the pack is ready to be discharged.
As soon as current is drawn from the battery pack on discharge, the computer changes the rotor to top-up mode. Then, typically, the lowest cells (i.e. with the lowest voltage) are then monitored for voltage at a specific current draw and the weakest cell is then topped up for a pre-determined time using the secondary battery. This cycle is continued throughout the discharge cycle.
Once the battery discharge indicator read indicates that all of the cells (or a predefined number) have reached a predetermined lower level, the car then enters a "Get me home mode". The current draw is then limited and low-cell top up cycle time is reduced to get the last bit of energy out of the pack. At no time is any individual cell S allowed to drop below critical a critical level, typically 2.5v for Li-ion batteries.
Rotor system The rotor is described with reference to Figures 6 to 10. The rotor includes a rotor body that is powered by a stepper motor -the rotor body can hence move in small steps around a circle. Arranged in the circle are multiple pairs of cell contact apertures formed through a thick, electrically insulating sheet; one pair for each cell in the battery traction pack, each aperture sufficiently distant from an adjoining aperture to remove the risk of shorting. At the rear face of each cell contact aperture, a cell contact is hard wired to a cell's terminal. The rotor body includes a pair of main contacts (cylindrical IS pins) that can be forced through a pair of cell contact apertures by a pusher plate activated by a solenoid; the main contacts are connected to the terminals of the secondary battery, so that they can connect the terminaJs of the secondary battery (as well as the secondary mains charger) to the terminals of each cell in the traction pack in succession as the rotor body steps around the circle. This is a simple, low-cost and robust mechanical arrangement that allows the secondary battery (as well as the secondary mains charger) to charge and discharge individual cells in the traction battery pack with no risk of incorrect connection or shorting across a cell.
High current distribution from the secondary pack to the traction pack is prioritised by a set of rules implemented via the master processor and physically via the rotor. When commanded, the software carries out the following: 1) Rotates the rotor a step at a time, until the reset switch is made. This occurs initially on switch-on and then every 15 minutes, for rotational accuracy.
2) Rotates the rotor until the two plus and minus contacts in the rotor line up with the cell requiring energy transfer.
3) The master solenoid is then fired bringing the main contacts into contact with the cell contacts.
4 A set of change over switches is now activated for Top up or Bleed setting depending on which way energy has to be transferred.
5) At this point the main transfer switches are closed, transferring energy to or from the cell via the flexible current harness connecting the rotor contacts to the DC to DC converter in the vehicle specific switching unit.
Because of the spacing between cell contacts, it is physically impossible for any contacts to be made incorrectly or cells shorted out.
The above described rotor works well for batteries with 32 cells. For batteries with more cells, e.g. 64 cells, linear shuttle arrangement instead of a rotor is desirable because a rotor arrangement would be too large to be practical. The linear shuttle operates in exactly the same manner as the rotor, as described above.
EVC Ultra range BMS The invention as implemented in the Electric Vehicles Company's "EVC ULTRA RANGE BMS" utill2es three micro computers integrated together to control the battery management duties above with the vehicle control computer commanding the drive system in real time to manage acceleration, deceleration and regenerative braking, giving total vehicle performance levels of over 7 Miles per 1Kw hour.
The "EVC ULTRA RANGE BMS" modular approach is designed for ease of maintenance in the field, there are no set ups, all vehicle specific configuration is carried out by software specific download either already in the units as supplled from the factory or with downloads via the internet.
The "EVC ULTRA RANGE BMS" has been developed to get the maximum range from a very small pack. The EVC vehicle conversions have between 8 to 15 1Kw hour packs depending on type and constantly exceed 60 miles per charge range for normal driving.
The Traction unit as shown in Figures 1 and 2 is a three phase AC drive system, this unit is mounted in close proximity to the AC motor and in one implementation comes ready to install with wiring harness and mounted on its water cooling jacket so as to supply any excess heat to the vehicle heating system, or to heat the traction battery to S its optimal 20 degree Celsius operating termperature. Heating the traction battery is achieved using a simple pipe that circulates heated water in a heat source placed under the battery; a thermostat is used to ensure that heat is applied when needed (especially important in very low temperatures). By keeping the traction battery close to its optimal temperature, we find that range is not substantially reduced in low ambient temperatures.
The Vehicle interface module as shown in Figures 1 and 2 controls non-traction electric systems -i.e. vehicle ancillaries such as electric heater, brake lights during regeneration, reverse lights, reverse warning horn, l2v vehicle charging unit, power steering pump output.
The Battery management system (BMS) module as shown in Figures 1 and 2 is the main component of the battery management. The system processor runs under the guidance of the vehicle processor and controls in one embodiment up to 32 lithium ion cells during ali states of bulk charge, top up charge, balancing and driving conditions.
The unit has the ability to charge or discharge at quite high currents any ccli at any time, this to maximise the life of the pack and attain the maximum range from the \Telncle 23 The Charging module as shown in Figures 1 and 2 is in one embodiment a highly efficient switch mode bulk charger capable of charging up to 32 lithium ion celis at up to 32 Amps. Input voltage could typicaliy be either 110 vac, or 240 vac.

Claims (10)

  1. CLAIMS1. A battery management system for an electric vehicle, in which the vehicle includes (a) a traction battery comprising multiple individual cells and (b) a secondary S battery providing power for non-traction electric systems in the vehicle; in which the battery management system enables the secondary battery to be used to provide charge to individual cells in the traction battery.
  2. 2. The battery management system of Claim 1, in which the non-traction electric systems include one or more of: vehicle power steering, lights, fan, electric heater, brake lights during regeneration, reverse lights, reverse \varning horn, 12v vehicle charging unit
  3. 3. The battery management system of Claim I or 2 in which the secondary battery IS is a lead-acid battery or Li-ion battery.
  4. 4. The battery management system of any preceding Claim in which the individual cells in the traction battery are U-ion cells.
  5. 5. The battery management system of any preceding Claim in which the battery management system is operable to enable the secondary battery to support weakening cells in the traction battery that are approaching a voltage threshold, taking them up from that voltage threshold.
  6. 6. The battery management system of any preceding Claim iii which, during discharge, the battery management system monitors cells for voltage at a specific current draw and the battery management system then causes the weakest cell to be topped up for a pre-deterrnined time using the secondary battery.
  7. 7. The battery management system of any preceding Claim 5 or 6 in which the threshold is a threshold below which the cells would suffer damage.
  8. 8. The battery management system of Claim 7 in which the threshold is approximately 2.SV for a Li-ion cell.
  9. 9. The battery management system of any preceding Claim 5 -7 in which, by S providing charge to these weakening cells, the battery management system enables the secondary battery to support any and all cells during the discharge until all cells in the traction battery are balanced at their lowest, safe threshold, hence avoiding the problem of prematurely restricting or terminating discharge from the entire battery.tO
  10. 10. The battery management system of any preceding Claim in which, once a battery discharge indicator indicates that all of the cells, or a predefined number, have reached a predetermined lower level, the vehicle then enters a limited current draw mode.IS11. The battery management system of any preceding Claim in which a mains voltage bulk charger charges the traction pack in normal charging phase and a mains voltage secondary charger unit charges individual cells that are lagging in the charge process.12. The batter management system of any preceding Claim including an electro-mechanical rotor used to charge or discharge any cell in the traction battery by connecting the terminals of an individual cell to the terminals of the secondary battery.13. The battery management systenTi of Claim 12 in which the rotor is used to charge any cell in the traction battery by connecting the terminals of an individual cell to the terminals of the secondary mains charger.14. The battery management system of Claim 12 or 13 in which the rotor includes a rotor body that is powered by a stepper motor.15. The battery management system of Claim 14 in which the rotor body can move in small steps around a circle and arranged in the circle are multiple pairs of cell contact apertures formed through a thick, electrically insulating sheet; one pair for each cell in the battery traction pack, each aperture sufficiently distant from an adjoining aperture to remove the risk of shorting.3 16. The battery management system of Claim 15 in which, at the rear face of each cell contact aperture, a cell contact is hard wired to a cell and the rotor body includes a pair of main contacts that can be forced through a pair of cell contact apertures in the electrically insulating sheet by a pusher plate activated by a solenoid; the main contacts are connected to the terminals of the secondary battery and, optionally, a mains voltage secondary charger, so that they can connect the terminals of the secondary battery to the terminals of each cell in the traction pack in succession as the rotor body steps around the circle.17. The battery management system of any preceding Claim I -11 in which a 13 linear shuttle is used to charge or discharge any cell in the traction battery by connecting the terminals of an individual cell to the terminals of the secondary battery.18. The battery management system of any preceding Claim including a heat source that takes heat from a traction unit powered by the traction battery to warm the traction battery to its optimal operating temperature.19. The battery management system of Claim I including a thermostat to control when heat is supplied to the heat source.20. An electric vehicle including a battery management system as described in any preceding Claim.*.:r: INTELLECTUAL . ... PROPERTY OFFICE Application No: GB 1106638.8 Examiner: Peter Easterfield Claims searched: ito 20 Date of search: 28 October 2011 Patents Act 1977: Search Report under Section 17 Documents considered to be relevant: Category Relevant Identity of document and passage or figure of particular relevance to claims X 1-3,5,7, US2004/0217736A1 9, 20 (BISCHOFF) see paras [0021] & [0042] Categories: X Document indicating lack of novelty or inventive A Document indicating technological background and/or state step of the art.Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention.same category.& Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO & US patent documents classified in the following areas of the UKCX: Worldwide search of patent documents classified in the following areas of the IPC B6OL; HO2J The following online and other databases have been used in the preparation of this search report WPI, EPODOC International Classification: Subclass Subgroup Valid From B6OL 0011/18 01/01/2006 HO2J 0007/00 01/01/2006 Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk
GB1106638.8A 2010-04-20 2011-04-20 Electric vehicle battery management system Expired - Fee Related GB2481670B (en)

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US9365120B2 (en) * 2013-03-29 2016-06-14 Fca Us Llc Techniques for enhanced battery pack recharging

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ATE362854T1 (en) * 1997-12-23 2007-06-15 Amerigon Inc RADIO FREQUENCY ENERGY MANAGEMENT SYSTEM
AU2003301366A1 (en) * 2002-10-15 2004-05-04 Chaojiong Zhang Rotary voltage equalizer
US7245108B2 (en) * 2002-11-25 2007-07-17 Tiax Llc System and method for balancing state of charge among series-connected electrical energy storage units
FR2927200B1 (en) * 2008-02-06 2013-03-29 Valeo Equip Electr Moteur ENERGY STORAGE DEVICE, IN PARTICULAR FOR A MOTOR VEHICLE
JP5235481B2 (en) * 2008-04-23 2013-07-10 三洋電機株式会社 Power supply for vehicle
CN101640430B (en) * 2009-09-07 2011-09-14 清华大学 Dynamic balancing device for vehicle power battery and dynamic balancing method

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GB201106638D0 (en) 2011-06-01

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