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
• • 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
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • 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
  • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
• • 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
  • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J2207/20—Charging or discharging characterised by the power electronics converter
• • 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

Definitions

• This invention relates to battery packs for mobile of portable devices, and in particular to such battery packs which comprise batteries having lithium- ion or lithium solid state cells.
• Ni-Cad Nickel Cadmium
• lithium-ion batteries have the advantage of being able to be manufactured into almost any form or shape. This is particularly convenient for portable devices such as mobile phones which have a small form factor and limited space available for the battery.
• lithium ion batteries now account for the vast majority of rechargeable batteries used in devices such as mobile phones, PDAs, personal communicators and the like.
• the operational characteristics of the lithium ion batteries are not the same as those of the previously used Ni-Cad battery.
• the output voltage of a fully charged Ni-Cad cell falls rapidly initially, from its fully charged voltage to a relatively stable operational voltage, and thereafter remain relatively constant; only when the NiCad cell is almost fully discharged does the voltage is again started to drop rapidly.
• a lithium-ion cell when fully charged, may have an output voltage of approximately 4.2V; the output voltage falls linearly during operation, until it reaches a voltage of approximately 2.5 V, when effectively the lithium-ion cell is fully discharged.
• a 2-cell lithium-ion battery may provide an operational output voltage which varies between 8.4 and 5.0 V; this presents significant challenges for the design of the power management system.
• the UK patent application publication GB2,270,793A1 discloses a method of addressing the problem of the variability of output voltage, by including within a lithium-ion battery pack a DC-DC converter which converts the variable direct output voltage from the lithium-ion battery into a fixed, lower, voltage.
• the voltage may be pre-selected.
• the DC-DC converter accommodates the variability of the direct output voltage from the battery, and presents the mobile of portable device with a stable voltage.
• a display may require a voltage between 5 and 10V, in order to power both the display itself and any required back light; similarly a flash unit may require a high voltage; a CPU made in contrast only require a voltage between 1.5 and 2.5V.
• the power management system for such portable devices often comprises several DC-DC converters to provide different voltages.
• an up-converter may be required to provide a higher voltage for a display system, and one or more down-converters may be required in order to supply suitable driver voltages for a CPU system.
• the functional units may require close control of their input voltage, so a dedicated DC-DC converter may be integrated into that functional unit, even where the same nominal voltage is available elsewhere in the device. Since the power management system has to provide several different voltages, some of which may be either above or below the output voltage from the battery pack, depending on the state charge of the battery pack, it will be appreciated that there is significant complexity to the power management system. There is thus an ongoing need for solutions which can simplify the power management systems for such portable and mobile devices.
• a battery pack for use with a portable device, the battery pack comprising one or a plurality of lithium-ion cells providing a first voltage, a DC-DC converter operable under control of a control unit and for converting the first voltage into a second voltage, an interface unit for receiving, in use, information from the portable device and supplying information to the control unit, the control unit being for controlling the DC-DC converter in response to the interface unit, wherein the DC-DC converter is adapted such that the second voltage can be greater than the first voltage.
• the battery Pack according to a first embodiment of the invention provides a solution to the above problem in that it can provide a voltage which is higher than the direct output voltage from the lithium-ion battery.
• the DC-DC converter may be any suitable type of converter, including either a boost converter or a buck-boost converter, and conveniently is an inexpensive capacitive converter.
• the battery pack further comprises at least one further DC-DC converter operable under control of the control unit, for converting the first voltage into at least one further voltage which is different from the second voltage.
• the DC-DC converter may be a multi-output DC-DC converter adapted to further convert the first voltage into at least one further voltage which is different from the second voltage.
• the battery pack is able to provide multiple voltages, in order to supply functional units within a portable device which operate at different voltages.
• this can reduce the overall number of components in the portable device, and since the solution concentrates more of the power management function within the battery pack, allows for significantly improved design of the device itself.
• the controller may control the magnitude of at least one of the second voltage and the at least one further voltage.
• the battery pack may be able to supply an output voltage or voltages, the magnitude of level of which are context specific: the context may be a temporary device state (such as charging a capacitor for a flash-discharge), or may be portable device-specific (so that the battery pack is compatible with portable devices which each require a different set of supply voltages.
• the interface unit may a digital interface unit. A digital interface unit provide a convenient and rugged means of communicating information to and from the battery pack.
• Such information can include, for instance, information on the state of charge of the battery pack, thus allowing the portable device to selectively switch-off higher power functions such as flash units, or LED torch functions, in order to conserve the remaining battery life for more essential functions.
• a digital interface can conveniently communicate device information to the battery pack, for instance, information as to whether particular voltage output is required by the device, so that the control unit may switch off un-needed DC-DC converters.
• the interface unit may further comprise at least one V-sense input for receiving voltage sense information from the portable device.
• V- sense also known as Kelvin probes or zero-current sensors
• Inclusion of V- sense information is particularly useful to ensure that an accurate voltage is supplied to the relevant functional unit in the device, and that compensation can be made for ohmic losses due to wiring/ routing etc. Since the DC-DC conversion is centralised in the battery pack, rather than distributed to immediately adjacent (or within) the appropriate functional unit, such losses may be significant, and it is particularly useful to be able to provide a means whereby they can be compensated.
• Figure 1 illustrates part of a conventional power management system for a portable device
• Figure 2 is a schematic of the power routing configuration of a battery pack according to an embodiment of the invention.
• Figure 3 is a schematic of a battery pack arranged according to an embodiment of the invention.
• FIG. 1 illustrates part of a conventional power management system for a portable device.
• the power management system includes a lithium-ion battery 102 within a battery pack 103.
• the battery pack provides a variable output voltage, which is distributed via links 105 to several DC-DC converters.
• the DC-DC converters may include a down-converter 110 which powers a voltage bus 120 providing voltage to power one or more functional units 106 and 107 of the portable device.
• the DC-DC converters may include converters which are specific to a particular functional unit and may be integral to that functional unit, such as shown for the DC-DC converter 111 which provides the power for functional unit 130 in order to drive device 132, and is contained within the unit 130.
• the DC-DC converters may include a converter which provides a voltage supply for, and is specific to a functional unit but not integral with that unit; this is shown in figure 1 at the DC- DC converter 112, which is located adjacent to, but not integral with, functional unit 131 and provides power for a device 133.
• figure 2 shows the battery pack in accordance with an embodiment of the present invention.
• the battery pack 203 includes lithium- ion battery 202 and incorporates either a multi-output DC-DC converter (not shown), or as shown in the figure, multiple separate DC-DC converters 210, 211 and 212. Each DC-DC converter outputs a separate constant output voltage.
• converter 210 may output a voltage of between 5 and 10V, and whereas converter 211 produces a constant output voltage, which is between 1 and 2.5 V and which is predetermined according to the functional units for which that voltage is required.
• any particular converter 212 can supply a predetermined fixed output voltage of "N" volts.
• the arrangement shown includes three DC-DC converters; however an appropriate number of converters may be less than or greater than three, depending on the specific requirements of the portable device for which the battery pack is intended.
• the individual DC-DC converters thus comprise secondary sources for different blocks in the portable device.
• the converters may operate in either up or down mode as appropriate.
• a converter which is capable of operating in either an up or a down at mode may be required to provide an output voltage at a particular predetermined voltage in a 5 to 10V range, since, during at least a partly discharged state of the battery, this voltage will exceed the direct voltage output from the battery: a buck-boost converter would be suitable for use in such a situation; in contrast, where the voltage is required within a 1 to 2.5 V range, a down converter will always be used, and either a buck converter or a buck-boost converter would be suitable for use in the situation.
• Suitable converter types include charge pumps (Integrated capacitor-based converters), or inductive DC-DC converters.
• Such DC-DC converters may conveniently be based on Passive Integrated Circuits (PICs) technology, such as is currently being development by NXP Semiconductors, and which can provide capacitors with suitably high spatial densities, for instance within the 100-300 nF/mm 2 range. This facilitates particularly space- efficient multiple output capacitive integrated charge pump DC-DC converters without the need for external components.
• Such multiple output DC-DC converters have very small dimensions and thus can be conveniently integrated into the battery pack.
• the individual converters 210, 211 and 212 are accessed and controlled by means of a serial interface 205.
• the serial interface 205 may be under the control of the portable device's microprocessor.
• serial interface 205 may be under the control of the phone's CPU.
• the phone's CPU can determine which voltages are required in order to drive for instance, a display unit, a flash system, or an RF block, in dependence on which of these functional units are in demand, and communicate this information to the battery pack by means of the serial interface 205. Since in general, down-converters have higher efficiencies than up-converters, it will be appreciated that the system will use a down-converter, in preference to an up converter, where-ever appropriate.
• the controller may serve the additional function of associating a particular output voltage (which would normally be tied to a specific output pin or output pad of the battery pack), with one of two DC-DC converters, depending on the charge state of the battery itself, thus performing dynamic allocation of the DC-DC converters.
• each of the converters comprising the battery pack can be programmed to ensure either constant current or constant voltage, as well as remaining stable both in time and over the operating temperature range of the device.
• Some functional units in the portable device may require constant current. This is the case for instance for an LED flashlight functional unit. However since LEDs show very significant forward voltage variation, it is not possible to rely on a fixed voltage to provide a constant current to achieve the desired output in this case. So in the case of a flashlight it is preferable to use DC-DC converter which can provide a constant current. Conversely, other circuits such as TFT display drivers or RF amplifiers require a constant voltage.
• each converter or some of the converters may have a V-sense or Kelvin contact.
• the data from the V-sense contact may be directed to the respective
• DC-DC converter or to the controller, or both.
• feedback can be organized via the digital serial interface, or via an analog V-sense line.
• Different embodiments may use either, or both or neither, of these two configurations of V-sense feedback.
• FIG. 3 shows a lithium-ion battery 302, which is contained within a battery pack 303.
• the battery pack includes a control unit 350 and several DC-DC converters - in the particular example shown in figure 3, there are three DC-DC converters 310, 311 and 312. Each DC-DC converter is under the control of control unit 350.
• An interface unit 340 provides communication means, for communication between the battery pack 303 and a portable device (not shown) for which the battery pack is intended. As shown, the communication means comprises a serial digital interface 360.
• the interface unit 340 also comprises the voltage outputs from the battery pack by means of individual output pins or pads.
• Interface unit 340 also includes V-sense or Kelvin probes, shown at 330, 321 and 332.
• control unit 350 controls the converters 310, 311 and
• Controller 350 may determine which of the converters 310, 311 and 31 to need be operational and which can be switched off; furthermore, in another embodiment, it may also be able to control the output voltage from any individual converter. Thus, the controller 350 may enable of the battery pack to be compatible with various portable devices, which require different voltage power supplies to each other, and to operate in constant current or constant voltage mode.
• a battery pack for use with portable of mobile devices, which comprises an integral DC-DC converter in addition to the Li-ion battery.
• the DC-DC converter is capable of providing an output voltage which is higher than the direct output of the Lithium-ion battery.
• the battery- pack further comprises at least one further DCDC converter to provide a second output voltage, which is different to the first output voltage.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)
• Secondary Cells (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=41356163

Family Applications (1)

Country Status (3)

Families Citing this family (5)

Family Cites Families (5)

• 2009
  • 2009-08-05 WO PCT/IB2009/053410 patent/WO2011015900A1/en active Application Filing
  • 2009-08-05 EP EP09786815A patent/EP2462651A1/de not_active Withdrawn
  • 2009-08-05 CN CN2009801612356A patent/CN102484292A/zh active Pending

Non-Patent Citations (1)

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