US20080185997A1 - Charged control device and battery pack employing it - Google Patents
Charged control device and battery pack employing it Download PDFInfo
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- US20080185997A1 US20080185997A1 US12/078,147 US7814708A US2008185997A1 US 20080185997 A1 US20080185997 A1 US 20080185997A1 US 7814708 A US7814708 A US 7814708A US 2008185997 A1 US2008185997 A1 US 2008185997A1
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- Prior art keywords
- charge
- circuit
- control information
- detection circuit
- secondary cell
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- 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
- H01M10/4257—Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
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- 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
- the present invention relates to a charge control device for controlling the charging of a secondary cell or battery (hereinafter collectively referred to as a “secondary cell” throughout the specification and the claims) by monitoring its charge state, and relates also to a battery pack employing such a charge control device.
- a charge control device for controlling the charging of a secondary cell or battery (hereinafter collectively referred to as a “secondary cell” throughout the specification and the claims) by monitoring its charge state, and relates also to a battery pack employing such a charge control device.
- FIG. 6 is a diagram showing circuit configuration of a related art battery pack incorporating a charge control device.
- the battery pack 1 ′ shown in this figure is composed of a rechargeable secondary cell 2 ′, a charge control IC 3 ′ for controlling the charging of the secondary cell 2 ′ by monitoring its charge state, feed terminals 4 a ′ and 4 b ′ to which direct-current electric power is fed from a charger (not shown), a switch device 5 ′ connected between the feed terminal 4 a ′ and the positive electrode of the secondary cell 2 ′, and a sense resistor 6 ′ connected between the negative electrode of the secondary cell 2 ′ and the feed terminal 4 b ′ (ground line).
- the sense resistor 6 ′ has a very low resistance (generally a few tens of m ⁇ ), which permits the charge current flowing through the secondary cell 2 ′ to be detected as a voltage.
- the charge control IC 3 ′ is built by sealing into a single package a first full charge detection circuit 31 ′ for checking whether the secondary cell 2 ′ is in the fully charged state or not by comparing its charge voltage with a predetermined reference voltage, a direct-current voltage source 32 ′ for generating the reference voltage, a second full charge detection circuit 34 ′ for checking whether the secondary cell 2 ′ is in the fully charged state or not by comparing the voltages at both ends of the sense resistor 6 ′, and a control circuit 35 ′ for controlling the feeding of electric power to the secondary cell 2 ′ by turning on and off the switch device 5 ′ according to the output signals of the first and second full charge detection circuits 31 ′and 34 ′.
- the charge control IC 3 ′ can monitor the charge state of the secondary cell 2 ′ and control its charging in a considerably satisfactory manner in this battery pack 1 ′.
- the reference voltage generated by the direct-current voltage source 32 ′ i.e., the level of the charge voltage at which the first full charge detection circuit 31 ′ recognizes the fully charged state
- the reference voltage generated by the direct-current voltage source 32 ′ is fixed at the time of circuit fabrication. This makes it impossible to cancel factors that cause variations in the reference voltage after the circuit fabrication (for example, the influence of stress occurring when the charge control IC 3 ′ is packaged or mounted on a circuit board) and fabrication-associated variations in the secondary cell 2 ′ itself, which is the target of monitoring by the charge control IC 3 ′.
- the fully charged state voltage level needs to be set rather low to ensure safe charging operation. This makes it impossible to make the most use of the charge capacity of the secondary cell 2 ′.
- the second full charge detection circuit 34 ′ is so configured to check whether the secondary cell 2 ′ is in the fully charged state or not by comparing the voltages at both ends of the sense resistor 6 ′, which is connected external to the charge control IC 3 ′. Therefore, by setting the resistance of the sense resistor 6 ′ appropriately, it is possible to vary the level of the charge current at which to recognize the fully charged state. However, since the sense resistor 6 ′ has a very low resistance, it tends to be influenced by variations in connection, wiring resistances, and other factors. Accordingly, this makes it extremely difficult to correct a variation in the voltage level at which the fully charged state is recognized.
- the level of the charge current at which the fully charged state is recognized also needs to be set rather low to ensure safe charging operation. And, this makes it impossible to make the most use of the charge capacity of the secondary cell 2 ′.
- the sense resistor 6 ′ connected externally, hampers the scaling-down and cost reduction of the battery pack 1 ′.
- the present invention is directed to a charge control device and battery pack employing it that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
- An object of the present invention is to provide a charge control device that can accurately control the charging of a secondary cell by canceling the influence of stress occurring when an IC is packaged or mounted on a circuit board and other factors, and to provide a battery pack employing such a charge control device.
- the charge control device and battery pack employing it includes a charge control device having a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to control information fed in directly from outside.
- a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell, a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a control information generation circuit for generating control information based on an external signal fed in directly from outside; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a control information generation circuit for generating control information by converting an analog external signal fed in directly from outside into digital data; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a control information generation circuit for generating control information based on an output result of the control circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a detection circuit, provided within the charge control device, for detecting a state of the charge control device; a control information generation circuit for generating control information based on a signal outputted from the detection circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- FIG. 1 illustrates a battery pack incorporated with a charge control device of a first exemplary embodiment of the present invention
- FIG. 2 illustrates a battery pack incorporated with a charge control device of a second exemplary embodiment of the present invention
- FIG. 3 illustrates a battery pack incorporated with a charge control device of a third exemplary embodiment of the present invention
- FIG. 4 illustrates a battery pack incorporated with a charge control device of a fourth exemplary embodiment of the present invention
- FIG. 5 illustrates a battery pack incorporated with a charge control device of a fifth exemplary embodiment of the present invention.
- FIG. 6 illustrates a battery pack incorporating a related art charge control device.
- FIG. 1 is a circuit configuration of a battery pack incorporating a charge control device of a first exemplary embodiment of the present invention.
- the battery pack 1 of the first exemplary embodiment is composed of a rechargeable secondary cell 2 (for example, a lithium ion cell), a charge control IC 3 for controlling the charging of the secondary cell 2 by monitoring its charge state, feed terminals 4 a and 4 b to which direct-current electric power is fed from a charger (not shown), and a switch device 5 (for example, a MOS transistor) connected between the feed terminal 4 a and the positive electrode of the secondary cell 2 .
- a rechargeable secondary cell 2 for example, a lithium ion cell
- a charge control IC 3 for controlling the charging of the secondary cell 2 by monitoring its charge state
- feed terminals 4 a and 4 b to which direct-current electric power is fed from a charger (not shown)
- a switch device 5 for example, a MOS transistor
- the charge control IC 3 is built by sealing into a single package a first full charge detection circuit 31 for checking whether the secondary cell 2 is in the fully charged state or not by comparing its charge voltage with a predetermined reference voltage, a variable direct-current voltage source 32 for generating the reference voltage, a sense resistor 33 connected between the negative electrode of the secondary cell 2 and the feed terminal 4 b (ground line), a second full charge detection circuit 34 for checking whether the secondary cell 2 is in the fully charged state or not by comparing the voltages at both ends of the sense resistor 33 , a control circuit 35 for controlling the feeding of electric power to the secondary cell 2 by turning on and off the switch device 5 according to the output signals of the first and second full charge detection circuits 31 and 34 , an offset circuit 36 for offsetting the level at which the second full charge detection circuit 34 inverts its output, and the feed terminal 4 c feeding the control information steadily from outside the charge control device to the variable direct-current voltage source 32 and the offset circuit 36 .
- the output signal level of the first full charge detection circuit 31 is low (at the logical low level) or high (at the logical high level) according to whether the charge voltage of the secondary cell 2 is lower or higher, respectively, than the reference voltage generated by the variable direct-current voltage source 32 .
- the output signal level of the second full charge detection circuit 34 is low or high according to whether the voltage across the sense resistor 33 is higher or lower, respectively, than the offset level set by the offset circuit 36 .
- the control circuit 35 recognizes that at least one of the charge voltage and charge current of the secondary cell 2 indicates the fully charged state, and opens the switch device 5 . With this configuration, it is possible to prevent the secondary cell 2 from being overcharged.
- variable direct-current voltage source 32 of the first exemplary embodiment can set the aforementioned reference voltage (i.e., the level of the charge voltage at which the first full charge detection circuit 31 recognizes the fully charged state) according to the control information read from outside the charge control device through the feed terminal 4 c .
- the offset circuit 36 of this embodiment can set the aforementioned offset level (i.e., the level of the charge current at which the second full charge detection circuit 34 recognizes the fully charged state) likewise according to the control information read from outside the charge control device through the feed terminal 4 c.
- the charge control IC 3 of the first exemplary embodiment of the present invention can easily change the set levels of the charge voltage and charge current at which the fully charged state is recognized, even after the charge control IC 3 is packaged or mounted on a circuit board, or after the secondary cell 2 is connected.
- the charge control IC 3 even after the charge control IC 3 is built into the battery pack 1 , it is possible to optimize the levels of the charge voltage and charge current at which to recognize the fully charged state by canceling all factors that cause variations in the reference voltage after the fabrication of the circuit (for example, the influence of stress occurring when the charge control IC 3 is packaged or mounted on a circuit board) and all fabrication-associated variations in the secondary cell 2 itself, which is the very target of monitoring by the charge control IC 3 .
- the fully charged state levels are set rather low to ensure safe charting operation, because approximately ⁇ 0.5% variations are inevitable in the charge voltage detected level and charge current detected level.
- the preferred embodiments of the present invention when detected levels are reduced to ⁇ 0.1% or smaller, it is not necessary to lower the levels of the fully charged state of both circuits 31 and 34 . This makes possible to use of the charge capacity of the secondary cell 2 more effectively.
- FIG. 2 is a circuit configuration of a battery pack incorporating a charge control. device of a second exemplary embodiment of the present invention.
- the numbers appearing in FIG. 2 which are identical to those of FIG. 1 , correspond to the same circuit elements as described in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements in FIG. 2 are omitted.
- a control information generation circuit 37 receives an external signal from outside through the feed terminal 4 c , and the control information generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offset circuit 36 .
- the external signal fed from outside to the control information generation circuit 37 includes a history signal (i.e., a history signal indicating the number of times that the cell has been charged thus far).
- the control information generation circuit may include a microcomputer.
- FIG. 3 is a circuit configuration of a battery pack incorporating a charge control device of a third exemplary embodiment of the present invention.
- the numbers appearing in FIG. 3 which are identical to those of FIG. 1 , correspond to the same circuit elements as described in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements in FIG. 3 are omitted.
- a control information generation circuit 37 receives an external signal from outside through the feed terminal 4 c , and the control information generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offset circuit 36 .
- the external signal fed from outside to the control information generation circuit 37 includes an analog signal (i.e., a temperature signal indicating the ambient temperature).
- the control information generation circuit may include an A/D conversion circuit that converts the analog external signal into a digital signal.
- FIG. 4 is a circuit configuration of a battery pack incorporating a charge control device of a fourth exemplary embodiment of the present invention.
- the numbers appearing in FIG. 4 which are identical to those of FIG. 1 , correspond to the same circuit elements as described in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements in FIG. 4 are omitted.
- a control information generation circuit 37 receives a feedback signal from the control circuit 35 , and the control information generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offset circuit 36 .
- the control information generation circuit may include a microcomputer.
- FIG. 5 is a circuit configuration of a battery pack incorporating a charge control device of a fifth exemplary embodiment of the present invention.
- the numbers appearing in FIG. 5 which are identical to those of FIG. 1 , correspond to the same circuit elements as described above in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements in FIG. 5 are omitted.
- a control information generation circuit 37 receives a signal from a detection circuit 38 provided within an LSI, and the control information generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offset circuit 36 .
- a plurality of detection circuits may be provided in the LSI, and one of the plurality of detection circuits 38 include a temperature detection circuit.
- the control information generation circuit 37 may include an A/D conversion circuit that converts the analog signal (i.e., temperature) into a digital signal.
- variable direct-current voltage source 32 of each of the preferred embodiment can set the reference voltage (i.e., level of the charge voltage at which the first full charge detection circuit 31 recognizes the fully charged state) according to the control information received.
- the offset circuit 36 of each of the preferred embodiments can set the offset level (i.e., level of the charge current at which the second full charge detection circuit 34 recognizes the fully charged state) likewise according to the control information received.
- charge control IC 3 of the preferred embodiments eliminate the need to connect a sense resistor externally outside the charge control device for detecting the charge current of the secondary cell 2 . This helps realize the scaling-down and cost reduction of the battery pack 1 .
- switch device 5 may be formed within the charge control IC 3 .
- the charge control device of the preferred embodiments can accurately control the charging of a secondary cell by canceling the influence of stress occurring when an IC is packaged or mounted on a circuit board and other factors.
Abstract
A battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to control information.
Description
- This application is a Continuation of co-pending U.S. patent application Ser. No. 11/092,977 filed on Mar. 30, 2005, which is a Continuation-In-Part of U.S. patent application Ser. No. 10/316,152 filed on Dec. 11, 2002 that issued as a U.S. Pat. No. 6,894,458 on May 17, 2005, and claims the benefit of the Japanese patent Application No. 2001-376771 filed on Dec. 11, 2001 in Japan.
- 1. Field of the Invention
- The present invention relates to a charge control device for controlling the charging of a secondary cell or battery (hereinafter collectively referred to as a “secondary cell” throughout the specification and the claims) by monitoring its charge state, and relates also to a battery pack employing such a charge control device.
- 2. Background of the Related Art
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FIG. 6 is a diagram showing circuit configuration of a related art battery pack incorporating a charge control device. The battery pack 1′ shown in this figure is composed of a rechargeablesecondary cell 2′, acharge control IC 3′ for controlling the charging of thesecondary cell 2′ by monitoring its charge state, feed terminals 4 a′ and 4 b′ to which direct-current electric power is fed from a charger (not shown), a switch device 5′ connected between the feed terminal 4 a′ and the positive electrode of thesecondary cell 2′, and a sense resistor 6′ connected between the negative electrode of thesecondary cell 2′ and thefeed terminal 4 b′ (ground line). The sense resistor 6′ has a very low resistance (generally a few tens of mΩ), which permits the charge current flowing through thesecondary cell 2′ to be detected as a voltage. - The
charge control IC 3′ is built by sealing into a single package a first fullcharge detection circuit 31′ for checking whether thesecondary cell 2′ is in the fully charged state or not by comparing its charge voltage with a predetermined reference voltage, a direct-current voltage source 32′ for generating the reference voltage, a second fullcharge detection circuit 34′ for checking whether thesecondary cell 2′ is in the fully charged state or not by comparing the voltages at both ends of the sense resistor 6′, and acontrol circuit 35′ for controlling the feeding of electric power to thesecondary cell 2′ by turning on and off the switch device 5′ according to the output signals of the first and second fullcharge detection circuits 31′and 34′. - As described above, the
charge control IC 3′ can monitor the charge state of thesecondary cell 2′ and control its charging in a considerably satisfactory manner in this battery pack 1′. - However, in the
charge control IC 3′ configured as described above, the reference voltage generated by the direct-current voltage source 32′ (i.e., the level of the charge voltage at which the first fullcharge detection circuit 31′ recognizes the fully charged state) is fixed at the time of circuit fabrication. This makes it impossible to cancel factors that cause variations in the reference voltage after the circuit fabrication (for example, the influence of stress occurring when thecharge control IC 3′ is packaged or mounted on a circuit board) and fabrication-associated variations in thesecondary cell 2′ itself, which is the target of monitoring by thecharge control IC 3′. Thus, in thecharge control IC 3′ configured as described above, the fully charged state voltage level needs to be set rather low to ensure safe charging operation. This makes it impossible to make the most use of the charge capacity of thesecondary cell 2′. - On the other hand, the second full
charge detection circuit 34′ is so configured to check whether thesecondary cell 2′ is in the fully charged state or not by comparing the voltages at both ends of the sense resistor 6′, which is connected external to thecharge control IC 3′. Therefore, by setting the resistance of the sense resistor 6′ appropriately, it is possible to vary the level of the charge current at which to recognize the fully charged state. However, since the sense resistor 6′ has a very low resistance, it tends to be influenced by variations in connection, wiring resistances, and other factors. Accordingly, this makes it extremely difficult to correct a variation in the voltage level at which the fully charged state is recognized. Thus, in thecharge control IC 3′ configured as described above, the level of the charge current at which the fully charged state is recognized also needs to be set rather low to ensure safe charging operation. And, this makes it impossible to make the most use of the charge capacity of thesecondary cell 2′. Moreover, the sense resistor 6′, connected externally, hampers the scaling-down and cost reduction of the battery pack 1′. - Accordingly, the present invention is directed to a charge control device and battery pack employing it that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
- An object of the present invention is to provide a charge control device that can accurately control the charging of a secondary cell by canceling the influence of stress occurring when an IC is packaged or mounted on a circuit board and other factors, and to provide a battery pack employing such a charge control device.
- Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
- To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the charge control device and battery pack employing it includes a charge control device having a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to control information fed in directly from outside.
- In another aspect, a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell, a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a control information generation circuit for generating control information based on an external signal fed in directly from outside; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- In another aspect, a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a control information generation circuit for generating control information by converting an analog external signal fed in directly from outside into digital data; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- In another aspect, a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a control information generation circuit for generating control information based on an output result of the control circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- In another aspect, a battery pack employing a charge control device includes a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell; a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; a detection circuit, provided within the charge control device, for detecting a state of the charge control device; a control information generation circuit for generating control information based on a signal outputted from the detection circuit; and a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to the control information outputted from the control information generation circuit.
- It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
- The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:
-
FIG. 1 illustrates a battery pack incorporated with a charge control device of a first exemplary embodiment of the present invention; -
FIG. 2 illustrates a battery pack incorporated with a charge control device of a second exemplary embodiment of the present invention; -
FIG. 3 illustrates a battery pack incorporated with a charge control device of a third exemplary embodiment of the present invention; -
FIG. 4 illustrates a battery pack incorporated with a charge control device of a fourth exemplary embodiment of the present invention; -
FIG. 5 illustrates a battery pack incorporated with a charge control device of a fifth exemplary embodiment of the present invention; and -
FIG. 6 illustrates a battery pack incorporating a related art charge control device. - Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
-
FIG. 1 is a circuit configuration of a battery pack incorporating a charge control device of a first exemplary embodiment of the present invention. The battery pack 1 of the first exemplary embodiment is composed of a rechargeable secondary cell 2 (for example, a lithium ion cell), acharge control IC 3 for controlling the charging of thesecondary cell 2 by monitoring its charge state,feed terminals 4 a and 4 b to which direct-current electric power is fed from a charger (not shown), and a switch device 5 (for example, a MOS transistor) connected between the feed terminal 4 a and the positive electrode of thesecondary cell 2. - The
charge control IC 3 is built by sealing into a single package a first fullcharge detection circuit 31 for checking whether thesecondary cell 2 is in the fully charged state or not by comparing its charge voltage with a predetermined reference voltage, a variable direct-current voltage source 32 for generating the reference voltage, asense resistor 33 connected between the negative electrode of thesecondary cell 2 and thefeed terminal 4 b (ground line), a second fullcharge detection circuit 34 for checking whether thesecondary cell 2 is in the fully charged state or not by comparing the voltages at both ends of thesense resistor 33, acontrol circuit 35 for controlling the feeding of electric power to thesecondary cell 2 by turning on and off the switch device 5 according to the output signals of the first and second fullcharge detection circuits circuit 36 for offsetting the level at which the second fullcharge detection circuit 34 inverts its output, and thefeed terminal 4 c feeding the control information steadily from outside the charge control device to the variable direct-current voltage source 32 and the offsetcircuit 36. - The output signal level of the first full
charge detection circuit 31 is low (at the logical low level) or high (at the logical high level) according to whether the charge voltage of thesecondary cell 2 is lower or higher, respectively, than the reference voltage generated by the variable direct-current voltage source 32. On the other hand, the output signal level of the second fullcharge detection circuit 34 is low or high according to whether the voltage across thesense resistor 33 is higher or lower, respectively, than the offset level set by the offsetcircuit 36. - When one of the output signal levels of the first and second full
charge detection circuits control circuit 35 recognizes that at least one of the charge voltage and charge current of thesecondary cell 2 indicates the fully charged state, and opens the switch device 5. With this configuration, it is possible to prevent thesecondary cell 2 from being overcharged. - Here, the variable direct-
current voltage source 32 of the first exemplary embodiment can set the aforementioned reference voltage (i.e., the level of the charge voltage at which the first fullcharge detection circuit 31 recognizes the fully charged state) according to the control information read from outside the charge control device through thefeed terminal 4 c. Moreover, theoffset circuit 36 of this embodiment can set the aforementioned offset level (i.e., the level of the charge current at which the second fullcharge detection circuit 34 recognizes the fully charged state) likewise according to the control information read from outside the charge control device through thefeed terminal 4 c. - With the above described configuration, the
charge control IC 3 of the first exemplary embodiment of the present invention can easily change the set levels of the charge voltage and charge current at which the fully charged state is recognized, even after thecharge control IC 3 is packaged or mounted on a circuit board, or after thesecondary cell 2 is connected. - Accordingly, even after the
charge control IC 3 is built into the battery pack 1, it is possible to optimize the levels of the charge voltage and charge current at which to recognize the fully charged state by canceling all factors that cause variations in the reference voltage after the fabrication of the circuit (for example, the influence of stress occurring when thecharge control IC 3 is packaged or mounted on a circuit board) and all fabrication-associated variations in thesecondary cell 2 itself, which is the very target of monitoring by thecharge control IC 3. - In the related art
charge control IC 3′ (FIG. 6 ), the fully charged state levels are set rather low to ensure safe charting operation, because approximately ±0.5% variations are inevitable in the charge voltage detected level and charge current detected level. However, in the preferred embodiments of the present invention, when detected levels are reduced to ±0.1% or smaller, it is not necessary to lower the levels of the fully charged state of bothcircuits secondary cell 2 more effectively. -
FIG. 2 is a circuit configuration of a battery pack incorporating a charge control. device of a second exemplary embodiment of the present invention. The numbers appearing inFIG. 2 , which are identical to those ofFIG. 1 , correspond to the same circuit elements as described in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements inFIG. 2 are omitted. - As shown in
FIG. 2 , a controlinformation generation circuit 37 receives an external signal from outside through thefeed terminal 4 c, and the controlinformation generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offsetcircuit 36. In the second exemplary embodiment of the present invention, the external signal fed from outside to the controlinformation generation circuit 37 includes a history signal (i.e., a history signal indicating the number of times that the cell has been charged thus far). The control information generation circuit may include a microcomputer. -
FIG. 3 is a circuit configuration of a battery pack incorporating a charge control device of a third exemplary embodiment of the present invention. The numbers appearing inFIG. 3 , which are identical to those ofFIG. 1 , correspond to the same circuit elements as described in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements inFIG. 3 are omitted. - As shown in
FIG. 3 , a controlinformation generation circuit 37 receives an external signal from outside through thefeed terminal 4 c, and the controlinformation generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offsetcircuit 36. In the third exemplary embodiment of the present invention, the external signal fed from outside to the controlinformation generation circuit 37 includes an analog signal (i.e., a temperature signal indicating the ambient temperature). The control information generation circuit may include an A/D conversion circuit that converts the analog external signal into a digital signal. -
FIG. 4 is a circuit configuration of a battery pack incorporating a charge control device of a fourth exemplary embodiment of the present invention. The numbers appearing inFIG. 4 , which are identical to those ofFIG. 1 , correspond to the same circuit elements as described in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements inFIG. 4 are omitted. - As shown in
FIG. 4 , a controlinformation generation circuit 37 receives a feedback signal from thecontrol circuit 35, and the controlinformation generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offsetcircuit 36. In the fourth exemplary embodiment of the present invention, the control information generation circuit may include a microcomputer. -
FIG. 5 is a circuit configuration of a battery pack incorporating a charge control device of a fifth exemplary embodiment of the present invention. The numbers appearing inFIG. 5 , which are identical to those ofFIG. 1 , correspond to the same circuit elements as described above in reference to the first exemplary embodiment of the present invention. Accordingly, written descriptions for identical circuit elements inFIG. 5 are omitted. - As shown in
FIG. 5 , a controlinformation generation circuit 37 receives a signal from adetection circuit 38 provided within an LSI, and the controlinformation generation circuit 37 feeds the control information to the variable direct-current voltage source 32 and the offsetcircuit 36. In the fifth exemplary embodiment of the present invention, a plurality of detection circuits may be provided in the LSI, and one of the plurality ofdetection circuits 38 include a temperature detection circuit. In addition, the controlinformation generation circuit 37 may include an A/D conversion circuit that converts the analog signal (i.e., temperature) into a digital signal. - As discussed in the preferred embodiments of the present invention, the variable direct-
current voltage source 32 of each of the preferred embodiment can set the reference voltage (i.e., level of the charge voltage at which the first fullcharge detection circuit 31 recognizes the fully charged state) according to the control information received. In addition, the offsetcircuit 36 of each of the preferred embodiments can set the offset level (i.e., level of the charge current at which the second fullcharge detection circuit 34 recognizes the fully charged state) likewise according to the control information received. - Moreover, adopting the
charge control IC 3 of the preferred embodiments eliminate the need to connect a sense resistor externally outside the charge control device for detecting the charge current of thesecondary cell 2. This helps realize the scaling-down and cost reduction of the battery pack 1. In addition, switch device 5 may be formed within thecharge control IC 3. - Accordingly, the charge control device of the preferred embodiments can accurately control the charging of a secondary cell by canceling the influence of stress occurring when an IC is packaged or mounted on a circuit board and other factors.
- It will be apparent to those skilled in art that various modifications and variations can be made in the charge control device and battery pack employing it of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Claims (6)
1. A battery pack employing a charge control device, comprising:
a charge detection circuit for checking whether a secondary cell is in a charged state or not based on at least a charge voltage or a charge current of the secondary cell;
a control circuit for controlling feeding of electric power to the secondary cell according to an output of the charge detection circuit; and
a setting circuit for setting a level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state according to control information.
2. The battery pack as claimed in claim 1 , further comprising:
a control information generation circuit receiving a control signal and generating the control information,
wherein the setting circuit receives the control information and, according to the control information, sets the level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state.
3. The battery pack as claimed in claim 2 ,
wherein the control signal is an analog signal.
4. The battery back as claimed in claim 2 ,
wherein the control information generation circuit generates the control information based on an output of the control circuit.
5. The battery pack as claimed in claim 1 , further comprising:
a detection circuit incorporated in the charge control device and detecting a state of the charge control device,
wherein, according to a result output from the detection circuit, the setting circuit sets the level of the charge voltage or the charge current at which the charge detection circuit recognizes the charged state.
6. The battery pack as claimed in claim 5 , further comprising:
a control information generation circuit receiving a signal from the detection circuit and, according to the signal from the detection circuit, generates the control information.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/078,147 US20080185997A1 (en) | 2001-12-11 | 2008-03-27 | Charged control device and battery pack employing it |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2001376771A JP2003180038A (en) | 2001-12-11 | 2001-12-11 | Charge controller |
JP2001-376771 | 2001-12-11 | ||
US10/316,152 US6894458B2 (en) | 2001-12-11 | 2002-12-11 | Charge control device and battery pack employing it |
US11/092,977 US7372234B2 (en) | 2001-12-11 | 2005-03-30 | Charge control device and battery pack employing it |
US12/078,147 US20080185997A1 (en) | 2001-12-11 | 2008-03-27 | Charged control device and battery pack employing it |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/092,977 Continuation US7372234B2 (en) | 2001-12-11 | 2005-03-30 | Charge control device and battery pack employing it |
Publications (1)
Publication Number | Publication Date |
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US20080185997A1 true US20080185997A1 (en) | 2008-08-07 |
Family
ID=19184895
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/316,152 Expired - Fee Related US6894458B2 (en) | 2001-12-11 | 2002-12-11 | Charge control device and battery pack employing it |
US11/071,201 Expired - Lifetime US6979978B2 (en) | 2001-12-11 | 2005-03-04 | Battery pack employing charge control device |
US12/078,147 Abandoned US20080185997A1 (en) | 2001-12-11 | 2008-03-27 | Charged control device and battery pack employing it |
Family Applications Before (2)
Application Number | Title | Priority Date | Filing Date |
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US10/316,152 Expired - Fee Related US6894458B2 (en) | 2001-12-11 | 2002-12-11 | Charge control device and battery pack employing it |
US11/071,201 Expired - Lifetime US6979978B2 (en) | 2001-12-11 | 2005-03-04 | Battery pack employing charge control device |
Country Status (2)
Country | Link |
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US (3) | US6894458B2 (en) |
JP (1) | JP2003180038A (en) |
Cited By (2)
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WO2017000103A1 (en) * | 2015-06-29 | 2017-01-05 | 深圳市大疆创新科技有限公司 | Control circuit, battery provided with control circuit and battery control method |
US11063448B2 (en) * | 2019-09-16 | 2021-07-13 | Zebra Technologies Corporation | Methods and system for dynamically modifying charging settings for a battery assembly |
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JP3872758B2 (en) * | 2003-01-08 | 2007-01-24 | 株式会社日立製作所 | Power control device |
US7508171B2 (en) * | 2003-10-14 | 2009-03-24 | Black & Decker Inc. | Protection methods, protection circuits and protective devices for secondary batteries, a power tool, charger and battery pack adapted to provide protection against fault conditions in the battery pack |
JP4225281B2 (en) * | 2005-02-09 | 2009-02-18 | トヨタ自動車株式会社 | Fuel cell system |
JP4668836B2 (en) * | 2006-05-09 | 2011-04-13 | ローム株式会社 | CHARGE CONTROL CIRCUIT AND CHARGE CIRCUIT AND ELECTRONIC DEVICE USING THE SAME |
JP4755153B2 (en) * | 2007-08-23 | 2011-08-24 | 株式会社リコー | Charging circuit |
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Also Published As
Publication number | Publication date |
---|---|
JP2003180038A (en) | 2003-06-27 |
US6894458B2 (en) | 2005-05-17 |
US20030122526A1 (en) | 2003-07-03 |
US20050140339A1 (en) | 2005-06-30 |
US6979978B2 (en) | 2005-12-27 |
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