JP2011109802A - Battery pack and charging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pack battery and a charging system wherein secondary batteries are safely charged by reliably notifying a charger of information required to safely charge the secondary batteries, and moreover the secondary batteries are safely charged even if an old type charger is used which detects a battery temperature for charge and control. <P>SOLUTION: According to the terminal voltages and the temperatures of the secondary batteries, charging conditions for safely charging the secondary batteries are divided into four steps, and control voltages having voltage levels different in four steps from each other are selectively output to the charger. In particular, according to the combination between a voltage region where the terminal voltages of the secondary batteries are pre-divided into three steps, and a temperature region where the temperature region charging the secondary batteries is pre-divided into two steps, one of the four preset charging conditions is selected in accordance with the terminal voltages and the temperatures of the secondary batteries. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides an old type charger that can securely charge a secondary battery by securely notifying the charger of information necessary for safely charging the secondary battery, and detecting the battery temperature to control charging. The present invention relates to a battery pack and a charging system that can be safely charged even when used.

  When a battery pack including a secondary battery is connected to a charger for charging, it is important to charge the secondary battery safely, as well as to efficiently charge the secondary battery to a fully charged state. In particular, when a lithium ion battery is used as a secondary battery, it is required to sufficiently ensure the safety of charging.

  Incidentally, the following standards are recommended as conditions (safety standards) for determining a charging voltage and a charging current for safely charging a lithium ion battery. In this standard, for example, as shown in FIG. 8, the upper limit charging voltage (charge prohibition voltage) in the standard temperature range (0 to 45 ° C.) is defined as 4.25 V / cell, and the high temperature range (45 to 60 ° C.). The upper limit charging voltage (charging prohibition voltage) is set to 4.15 V / cell, and charging itself is prohibited when the temperature is outside the above temperature ranges (0 ° C. or lower or 60 ° C. or higher). Further, the maximum charging current for the secondary battery is also set as, for example, 0.5 C in the low temperature range (0 to 10 ° C.) in the standard temperature range, and 1.0 C in other than the low temperature range (10 to 60 ° C.). . It is also possible to set the maximum charging current as 1.0 C or 1.5 C over the entire standard temperature range (0 to 60 ° C.).

  Voltage detecting means for detecting the terminal voltage (cell voltage) of the secondary battery in the battery pack provided with the secondary battery in order to charge the secondary battery while satisfying the safety conditions defined in this way, and the secondary battery Temperature detecting means for detecting the temperature (cell temperature) of the battery, and controlling charging of the secondary battery according to the voltage and temperature detected by each of the detecting means has been proposed (for example, Patent Document 1). See). Specifically, Patent Document 1 discloses that the charging voltage for the secondary battery is limited according to the battery temperature, and further, the secondary battery is charged while limiting the charging current.

  In Patent Document 1, a maximum charging voltage is defined for each pre-divided temperature range, and when the terminal voltage of the secondary battery is higher than the maximum charging voltage, a signal of a voltage level determined for each temperature range is disclosed. Is output to an electronic device (eg, a charger).

JP 2009-44946 A

  By the way, in order to perform the above-described charge control, it is necessary to construct a battery pack and a charger to which the battery pack is connected based on a predetermined charge control specification. Specifically, as shown in FIG. 9, for the battery pack A configured to output various charge control signals from the control terminal CHG, the battery charger B determines the charge control signal and determines the battery pack. (Secondary battery) It is necessary to provide a control unit for controlling charging of A. However, when a charge control signal as shown in Patent Document 1 described above is transmitted to the charger B via the control terminal CHG, it is generally denied that the control in the charger B is complicated. Absent.

  In FIG. 9, 1 is a secondary battery in which a plurality of battery cells are connected in series and parallel, 2 is a voltage detector for detecting a terminal voltage (cell voltage) of the secondary battery (battery cell) 1, and 3 is a secondary battery. A current detection unit for detecting the charge / discharge current of the battery 1, 4 is a thermistor as temperature detection means for detecting the temperature of the secondary battery 1, 5 is a charge control unit configured by a microcomputer, a protection IC, etc. Is a FET for protecting a secondary battery that is inserted in series in the charging / discharging path of the secondary battery 1 and driven by the charge control unit 5. Reference numeral 8 denotes a power supply unit that supplies charging power to the secondary battery 1, and reference numeral 9 denotes a control unit that is configured by a microcomputer or the like and controls the charging operation of the power supply unit 8.

  On the other hand, the conventional general battery pack (old battery pack) C includes only a temperature terminal (thermistor terminal) TH for detecting the battery temperature as shown in FIG. 8, for example. The charger (old charger) D for charging the battery pack C detects, for example, the terminal voltage of the secondary battery 1 from its output terminal, and the battery pack (secondary battery 1) via the temperature terminal TH. By detecting this temperature, charging of the secondary battery 1 is controlled separately from the battery pack C. That is, the battery pack C and the charger D constitute a charging system having a system different from the charging system constructed by the battery pack A and the battery charger B described above.

  However, as shown by the broken line in FIG. 9, there is a demand to safely charge the secondary battery 1 even when the above-described battery pack A is attached to the old type charger D. However, in this case, the old-type charger D does not have a function for determining the meaning of the charge control signal provided from the battery pack A, so that the charge control signal is effectively used to execute the charge control. There is a problem that can not be.

  The present invention has been made in consideration of such circumstances, and its purpose is to securely notify the charger of information necessary for safely charging the secondary battery, and to safely charge the battery, It is another object of the present invention to provide a battery pack and a charging system that can be safely charged even when using the above-mentioned old type charger.

  That is, the present invention simply and reliably notifies the charger of charging control information for safely charging the secondary battery determined by the terminal voltage and battery temperature of the secondary battery detected in the battery pack. In addition to simplifying the charging control by the charger, the secondary battery can be safely charged even when the battery pack is connected to an old type charger that does not have such a charging control function. It aims to provide a battery pack and a charging system.

In order to achieve the above-mentioned object, the battery pack according to the present invention includes a secondary battery, voltage detection means for detecting a terminal voltage of the secondary battery, temperature detection means for detecting the temperature of the secondary battery, and these A logic circuit that divides charging conditions for safely charging the secondary battery according to the terminal voltage and temperature of the secondary battery detected by each of the detection means, and an output of the logic circuit An output circuit that selectively gives a control voltage of a plurality of different voltage levels to a charger that charges the secondary battery according to
The logic circuit previously classifies a voltage range in which the terminal voltage of the secondary battery is divided into a plurality of stages (for example, three stages) and a temperature range in which the secondary battery can be charged into a plurality of stages (for example, two stages). One of a plurality of (for example, four) charging conditions determined in advance according to the combination with the temperature region is selected according to the terminal voltage and temperature of the secondary battery respectively detected by the detection means. It is characterized by that.

Incidentally, the temperature range in which the secondary battery can be charged is, for example, a standard temperature range (for example, 0 to 45 ° C.) and a high temperature range (for example, 45 to 60 ° C.),
The voltage threshold value for dividing the voltage range of the plurality of stages (for example, three stages) is a standard recommended charging voltage in the standard temperature range and a high temperature recommended charging voltage in the high temperature range set lower than the standard recommended charging voltage. ,
The logic circuit is in a charge prohibited state in which charging of the secondary battery is prohibited when the temperature of the secondary battery is outside the standard temperature range and the high temperature range (0 ° C. or lower or 60 ° C. or higher). A current limiting state in which the secondary battery is allowed to be charged by limiting a charging current of the secondary battery when the battery temperature is in the standard temperature range and the terminal voltage of the secondary battery is equal to or higher than the standard recommended charging voltage; When the temperature of the secondary battery is in the high temperature range and the terminal voltage of the secondary battery is equal to or higher than the high temperature recommended charging voltage, the secondary battery is limited to a voltage limiting state in which charging is permitted by limiting the charging voltage. Is configured to alternatively generate output signals each indicating a charge permission state permitting charging of the secondary battery at a recommended charge voltage in a corresponding temperature range.

The control voltage is generated, for example, as a voltage at which the voltage level of the output signal of the logic circuit decreases stepwise in the order of the charging prohibited state, the charging permitted state, the voltage limiting state, and the current limiting state. .
The secondary battery includes a plurality of lithium ion batteries connected in series and parallel, and the voltage detection means detects a cell voltage of the lithium ion battery.

Moreover, the charging system according to the present invention comprises a battery pack having the above-described configuration and a charger that is connected to the battery pack and charges the secondary battery.
The charger is configured to include a charge control unit that determines a level of a control voltage applied from the battery pack and limits a charging voltage and / or a charging current applied to the secondary battery.

Alternatively, the charger inputs the control voltage supplied from the battery pack as temperature information of the secondary battery, and the level of the control voltage is out of the voltage range defined by the preset upper limit voltage and lower limit voltage. When the temperature of the secondary battery is out of the temperature range in which the secondary battery can be charged, the charging of the secondary battery is stopped.
In particular, the output circuit in the battery pack has a voltage range defined by the upper limit voltage and the lower limit voltage when the charge condition selected by the logic circuit is prohibition of charge and / or when the charge current is limited. It is configured to output a control voltage having a voltage level outside the range.

  According to the battery pack of the present invention, the charging conditions for safely charging the secondary battery include a plurality of (for example, four) charging conditions depending on the terminal voltage (cell voltage) of the secondary battery and the battery temperature. These charging conditions are simply output as control voltages (for example, four-state outputs) at different voltage levels in a plurality of stages (for example, four stages), so the above charging conditions are easily and reliably notified to the charger. can do.

  Further, since the charger only determines the control voltages having different voltage levels in the plurality of stages (for example, four stages), the determination process is easy, and charge control for the secondary battery can be left to the pack battery. Therefore, the control can be simplified.

  In particular, as a charging condition for safely charging the secondary battery, the temperature range in which the secondary battery can be charged is set, for example, as a standard temperature range (for example, 0 to 45 ° C.) and a high temperature range (for example, 45 to 60 ° C.). When the temperature is outside the above temperature range (standard temperature range and high temperature range) (for example, 0 ° C. or lower or 60 ° C. or higher), charging of the secondary battery is uniquely prohibited. If the temperature of the secondary battery is included in the standard temperature range, whether or not the terminal voltage of the secondary battery exceeds the standard recommended charging voltage, and if it is in the high temperature range, the secondary battery Since the mode of charge control is only selected depending on whether the terminal voltage exceeds the recommended high temperature charging voltage set lower than the standard recommended charging voltage, the secondary battery can be easily simplified while ensuring the safety of the secondary battery. Can be charged.

  In addition, when the charger is of an old type that does not support the above-described charging control, the control signal described above is given as temperature information for turning on / off the operation of the charger. The secondary battery can be safely charged by effectively utilizing the function of the charger. Specifically, when charging a secondary battery with current limiting, since the secondary battery has already been charged to some extent, the information indicating the current limitation described above is regarded as an increase in battery temperature, and charging is performed. The secondary battery can be safely charged by temporarily stopping.

The principal part schematic block diagram of the battery pack which concerns on one Embodiment of this invention. The figure which shows the example of the charging conditions for charging the said secondary battery set safely according to the determination division with respect to the terminal voltage and battery temperature of a secondary battery, and these determination divisions. The figure which shows the relationship between the charging conditions shown in FIG. 2, and the control voltage output according to the charging conditions. The figure which shows the structural example of the output circuit which selectively produces | generates the control voltage of a mutually different voltage level of four steps. The figure which shows another structural example of an output circuit. The figure which shows the example of the flow of the charge control in a charger. The figure which shows the mode of the change of the battery temperature accompanying charge control, and the change of a charging voltage and a charging current. The figure which shows the example of the safety standard with respect to charge of a lithium ion battery. The figure which shows the connection relation between the set of the pack battery and charger which took charge safety measures, and the set of the pack battery and charger which has not taken safety measures.

Hereinafter, a battery pack according to an embodiment of the present invention and a charging system for the battery pack will be described with reference to the drawings.
The battery pack E according to this embodiment basically has the same configuration as the battery pack A shown in FIG. Specifically, the battery pack E is charged by an external device (charger) via a pair of charge / discharge terminals [+], [−], and is connected to the pair of charge / discharge terminals [+], [−]. The external battery (electronic device) is provided with a secondary battery 1 that discharges charging power. The secondary battery 1 is configured by connecting a plurality of secondary battery cells, for example, lithium ion battery cells in series and parallel. The example shown in FIG. 1 shows a secondary battery 1 having a configuration in which battery cells connected in parallel two by two are connected in series. The configuration is determined according to the voltage / current specifications required for the battery pack E. Just do it.

  Incidentally, when the secondary battery 1 is a lithium ion battery, the charging to the battery pack E basically restricts the maximum charging current to about 0.5 to 1.0 C and sets the maximum charging voltage to 4. It is performed by constant current / constant voltage charging regulated to about 2 V / cell. When the terminal voltage (cell voltage) of the secondary battery 1 reaches a predetermined set value or more, or when the charging current decreases to a predetermined set value or less, this is detected as a full charge, and the charging is stopped. Is done.

  The battery pack E is inserted in series in the voltage detector 2 that detects the terminal voltage of the secondary battery 1 as a cell voltage for each battery cell in each stage, and the charge / discharge path of the secondary battery 1. A current detection unit 3 for detecting the charging / discharging current of the secondary battery 1 is provided, and a thermistor (temperature detection means) 4 for detecting the temperature of the battery pack E, and hence the temperature of the secondary battery 1 (cell temperature). Prepare.

  The charge control unit 5 configured by a microcomputer, a protection IC, and the like controls the charging of the secondary battery 1 and plays a role of protecting the secondary battery 1 from overcharge and overdischarge. Specifically, the charging control unit 5 includes a terminal voltage (cell voltage) of the secondary battery 1 detected by the voltage detection unit 2 and a temperature (cell) of the secondary battery 1 detected via the thermistor 4. The charging of the secondary battery 1 is controlled according to the temperature), and the secondary battery 1 is protected from an abnormal current based on the charge / discharge current detected by the current detector 3.

  Incidentally, the protection of the secondary battery 1 by the charge control unit 5 selectively drives the charge prohibiting and discharge prohibiting FETs 6, 7 inserted in series in the charge / discharge path of the secondary battery 1, Is performed by blocking the charge / discharge path of the secondary battery 1. The charging prohibiting and discharging prohibiting FETs 6 and 7 are provided in the positive charge / discharge path of the secondary battery 1 instead of the negative charge / discharge path of the secondary battery 1 shown in FIG. In some cases.

  Basically, in the battery pack configured as described above, the battery pack E according to the present invention is characterized in that the charge control unit 5 determines the terminal voltage (cell voltage) of the secondary battery 1 and the secondary battery. In accordance with the temperature (cell temperature) of 1, the battery pack E is connected to the charger used for charging the secondary battery 1 so as to output a control signal for controlling the charging operation. It is in the point. In particular, the charging control unit 5 charges the secondary battery 1 because the temperature range is defined (recommended) as shown in FIG. 7 as a charging safety standard capable of safely charging the lithium ion battery. For example, the possible temperature range is divided into a standard temperature range of 0 to 45 ° C. and a high temperature range of 45 to 60 ° C., and charging of the secondary battery 1 is prohibited in other temperature ranges. ing.

  More specifically, the charging control unit 5 determines whether or not the temperature T of the secondary battery 1 is 0 ° C. or less (T ≦ 0 ° C.), and the temperature T of the secondary battery 1 is 60. It is determined whether or not the temperature is higher than or equal to ° C. (60 ° C. ≦ T). When these determination conditions are satisfied, charging of the secondary battery 1 is prohibited. When the above determination condition is not satisfied, that is, when charging of the secondary battery 1 is permitted, it is determined whether the temperature T of the secondary battery 1 is in the standard temperature range or the high temperature range. Done. This determination is performed, for example, by determining whether or not the temperature T of the secondary battery 1 is 45 ° C. or higher (45 ° C. ≦ T). Therefore, strictly speaking, the standard temperature range described above is set as 1 to 44 ° C. (0 ° C. <T <45 ° C.), and the high temperature range is set as 45 to 59 ° C. (45 ≦ T <60 ° C.).

  In addition, the charging control unit 5 has an upper limit charging voltage and a maximum charging current at which the lithium ion battery can be safely charged, according to the battery temperature range divided as shown in FIG. The recommended charging voltage set based on the upper limit charging voltage in each temperature range is used as a threshold value for determining the battery voltage (cell voltage) of the secondary battery 1. Specifically, in the standard temperature range, a standard recommended charging voltage (for example, 4.20 V / cell) determined based on the upper limit charging voltage (4.25 V / cell) is set as the determination threshold value. In the high temperature range, a high temperature recommended charging voltage (for example, 4.10 V / cell) determined based on the upper limit charging voltage (4.15 V / cell) in the high temperature range is used as the determination threshold.

  In the standard temperature range, when the terminal voltage (cell voltage) of the secondary battery 1 exceeds the standard recommended charging voltage (for example, 4.20 V / cell), the secondary battery 1 is fully charged. If the maximum charging current is limited and charging is performed, and the terminal voltage (cell voltage) of the secondary battery 1 exceeds the high temperature recommended charging voltage (for example, 4.10 V / cell) in a high temperature range, The charging is controlled so as to charge the secondary battery 1 while limiting the charging voltage.

  In other words, the logic circuit 5a in the charge control unit 5 has a battery temperature T in the standard temperature range and the high temperature range as shown in FIG. 2 according to the terminal voltage (cell voltage) of the secondary battery 1 and the battery temperature. If the battery is out of the range (T ≦ 0 ° C. or 60 ° C. ≦ T), a status [charging prohibited state; 4] is set to prohibit charging of the secondary battery 1 regardless of the terminal voltage of the secondary battery 1. ing.

  In addition, the logic circuit 5a described the terminal voltage (cell voltage) of the secondary battery 1 when the battery temperature T of the secondary battery 1 is in the standard temperature range (0 ° C. <T <44 ° C.). Compared with the threshold (standard recommended charging voltage). Then, until the terminal voltage (cell voltage) V exceeds the standard recommended charging voltage (for example, 4.20 V / cell), a status [charging permission state; 1] that allows normal charging by constant current / constant voltage charging is set. When the terminal voltage (cell voltage) V exceeds the standard recommended charging voltage, a status [current limiting state; 2] is set to limit the charging current to 1/2 of the maximum charging current, for example. is doing.

  Further, when the battery temperature T of the secondary battery 1 is in a high temperature range (45 ° C. <T <59 ° C.), the logic circuit 5a described the terminal voltage (cell voltage) of the secondary battery 1 as described above. Comparison with the threshold (high temperature recommended charging voltage) is made. Then, until the terminal voltage (cell voltage) V exceeds the above-described high-temperature recommended charging voltage (for example, 4.10 V / cell), the status of permitting normal charging by the above-described constant current / constant voltage charging [charging permission state; 1] When the terminal voltage (cell voltage) V exceeds the high temperature recommended charging voltage, a status [voltage limiting state; 3] for limiting the charging voltage is set.

  The output circuit 5b in the charge control unit 5 receives the determination output result (status) from the logic circuit 5a described above, and generates a control signal of a voltage level determined according to each status, for example, as shown in FIG. This is output from the control terminal CHG described above. Incidentally, for the status indicating the charge prohibition state [4], the output circuit 5a has the highest voltage (for example, 1.7V) that the above-described old-type charger D can detect as a temperature abnormality (high temperature abnormality). Set as In addition, for the status indicating the current limit state [2] described above, since the secondary battery 1 is almost fully charged, the above-described old type charger D can be detected as a temperature abnormality (low temperature abnormality). The lowest voltage (for example, 0V) is set.

  Further, the output circuit 5b generates, for example, 1.5V as a voltage that the old type charger D can reliably detect as charging permission for the status indicating the charging permission state [1] described above. For the status indicating the voltage limit state [3], for example, 1.3 V is generated.

  The different voltages of the control signals indicating these four statuses indicate that the driving voltage of the microcomputer and the protection IC constituting the charging control unit 5 varies within a range of 3 to 5 V, for example, and the internal reference thereof. The reference voltage is determined in consideration of setting as 2.3 V, for example. Further, which status is associated with which voltage is determined in consideration of the detection characteristics (operating characteristics) of the old-type charger D described above. Therefore, when the operation specification of the charging control unit 5 is different from the above-described example, the old-type charger D can determine that charging is prohibited at least in the charging prohibited state [4] and the current limiting state [2]. Needless to say, each voltage level may be determined according to the specifications. It is of course possible to reverse the magnitude relationship of the voltage level corresponding to each status.

  For the output circuit 5a that generates the control signal set as described above, for example, as shown in FIG. 4, the power supply voltage (internal reference voltage) is divided to voltages of 1.7V, 1.5V, and 1.3V. The output of the resistor ladder circuit 51 that generates the signal is selected via the switch circuit 52 that is selectively turned on in response to the output of the logic circuit 5a, and this is output to the outside via the output buffer 53. good.

  Alternatively, for example, as shown in FIG. 5, the output from the logic circuit 5a is obtained as a signal subjected to pulse width modulation (PWM modulation) according to each status described above, and the voltage corresponding to the pulse width is obtained in the level shift circuit 54. It is also possible to convert this into an output buffer (FET) 55 and output it. In this case, for example, the pull-up resistor R provided on the side of the chargers B and D is used to charge the capacitor 56 externally attached to the output circuit 5b, and the charge voltage is taken out as an external output. It is preferable.

  Thus, as described above, according to the battery pack that selectively outputs the four control signals having different voltage levels according to the terminal voltage (cell voltage) of the secondary battery 1 and the battery temperature, charging according to the specifications is performed. In the device B, for example, as shown in FIG. 6, it is possible to easily control the charging of the battery pack while ensuring the safety of the battery pack only by determining the control signal given from the battery pack side.

  Specifically, the charger B determines the state of the control signal output from the battery pack <steps S1 to S4>, and interrupts the charging of the secondary battery 1 if the control signal is state [4] < Step S5>. If the control signal is state [1], charging of the secondary battery 1 is controlled in accordance with the state at that time (step S6). Specifically, if normal charging is in progress, the normal charging is continued.If charging is interrupted, charging is resumed.If charging is being performed with the voltage lowered, charging is based on the charging voltage. Return and charge normally.

  If the control signal is in state [2], the charging current is limited and charged (step S7), and if the control signal is in state [3], the charging voltage is limited and charged (step S8). The above process is repeatedly executed until full charge of the secondary battery 1 is detected <step S9>. Then, when the charging of the secondary battery 1 is completed, for example, by determining the open terminal voltage OCV of the secondary battery 1 <Step S10>, the secondary battery 1 is normally charged or remains charged or more. It is determined whether the charging is finished.

  Therefore, according to the above-described charging control, the battery pack is charged while the charging current is regulated according to the battery temperature T and the terminal voltage, for example, as shown in FIG. Specifically, when charging of the secondary battery 1 is started in a normal temperature state (for example, 10 ° C. <T <44 ° C.), the secondary battery 1 is charged with the constant current / constant voltage described above according to the charge permission status [1]. Is normally charged. With this charging, the terminal voltage (cell voltage) of the secondary battery 1 gradually increases, and the relative charge capacity RCOC of the secondary battery 1 also gradually increases as shown by the broken line in FIG.

  When the secondary battery 1 is continuously charged to some extent, the temperature T of the secondary battery 1 gradually increases due to the self-heating, and the terminal voltage ( The cell voltage) also increases gradually. In such a charging process, when the terminal voltage of the secondary battery 1 reaches the standard recommended charging voltage (for example, 4.20 V / cell) described above, a current limiting status [2] is output from the battery pack. Charging current is limited. This current limitation is performed, for example, by setting the charging current to 0.7 times the previous charging current. Then, the self-heating of the secondary battery 1 is suppressed along with the limitation of the charging current, and the temperature of the secondary battery 1 slightly decreases. As a result, the battery temperature is maintained in a low temperature range, and the terminal voltage is also equal to or lower than the standard recommended charging voltage, so that the above-described status is returned to [1] that commands charging permission. The secondary battery 1 is charged under the newly set charging current (limited charging current).

  However, at this time, since the secondary battery 1 has already been charged to some extent, even when charging under the current limit described above, the terminal voltage becomes the above-mentioned standard recommended charging voltage within a relatively short time. Reach. Therefore, in the battery pack, the status is set to [2] again to give a current limit command to the charger. As a result, the above-described reduction in the amount of charge is performed again, and accordingly, the battery temperature decreases and the terminal voltage also decreases. Therefore, the charging of the secondary battery 1 is continued again with the status set to [1]. . Thereafter, whenever the terminal voltage of the secondary battery 1 reaches the standard recommended charging voltage, the status [2] is issued and the charging current is reduced stepwise.

  Although not illustrated in FIG. 7, if the temperature of the secondary battery 1 exceeds 45 ° C. in the charging process described above, status [3] is issued and a command for limiting the charging voltage is given. . When the heat generation of the secondary battery 1 is suppressed by the limitation of the charging voltage and the battery voltage returns to the low temperature range, the charging of the secondary battery 1 is continued again under the current limitation described above. The When the charging current of the secondary battery 1 becomes a predetermined set value or less and the terminal voltage reaches a predetermined set value, it is determined that the secondary battery 1 has reached full charge, Stop charging.

  In this way, according to the charge control for charging the secondary battery 1 while variably setting the charging conditions according to the battery temperature and the terminal voltage of the secondary battery 1, the charging is performed when the battery temperature exceeds 45 ° C. Since the voltage itself is limited and the charging current is limited every time the terminal voltage exceeds the set voltage, the secondary battery 1 is fully charged while keeping the temperature of the secondary battery 1 at 45 ° C. or lower. It can be charged stably. Moreover, since the secondary battery 1 is charged while gradually reducing the charging current, the effect of being able to accurately determine the full charge can be achieved.

  The above-described battery pack is an old type that does not have the above-described charging condition control function. When connected to the charger D, the charger D determines only whether or not the voltage level of the control signal supplied from the battery pack satisfies the condition for permitting charging shown in FIG. . When the control signal is in the state [4] and the temperature of the secondary battery 1 is shown to be abnormal in high temperature, the charger D immediately stops charging. When the control signal is in the state [2] indicating the current limit, the charger D regards this as a temperature abnormality of the secondary battery 1 and stops the charging. The charger D executes the charging of the secondary battery 1 only when the control signal is in the state [1] indicating charging permission or the state [3] indicating voltage limitation.

  Therefore, according to the battery pack configured as described above, not only when connected to the charger B according to the specifications, but also when connected to the old type charger D, the charger B, D Thus, charging can be safely controlled by appropriately giving a charging control instruction. For the charger side, the charge control can be entrusted to the pack battery side, so that the control can be simplified.

  Furthermore, according to the battery pack according to the present invention, as described above, four control signals having different voltage levels are selectively output according to the terminal voltage (cell voltage) of the secondary battery 1 and the battery temperature to charge the battery. Since only the conditions are controlled, the above-described one control terminal CHG can also serve as the role of the thermistor terminal TM in the conventional battery pack. In other words, in the old-type charger D, the control terminal CHG can be regarded as the thermistor terminal TH, and charging thereof can be controlled. For this reason, the number of terminals provided in the battery pack does not increase, and the effect that a plurality of terminals can share the respective roles can be achieved.

  The present invention is not limited to the embodiment described above. The voltage levels of the control signals indicating the four states described above may be determined according to the specifications, and the correspondence between the four states and the voltage levels is determined by the detection characteristics (detection of the old type charger). It is sufficient to set it in consideration of the specifications. In addition, although charging of a lithium ion battery has been illustrated here, the present invention can be similarly applied to control charging of another type of secondary battery.

  Further, as described in the background art described above, the maximum charging current for the secondary battery is, for example, 1.0 C at a low temperature range (0 to 10 ° C.) in a standard temperature, and at a temperature other than the low temperature range (10 to 60 ° C.). It is also possible to use 1.5C. In this case, the charging current is reduced in a low temperature range (0 to 10 ° C.). As for the reduction of this current, as described above, the charging current may be uniquely limited to ½, or may be limited to about 2/3 (for example, reduced from 1.5 C to 1.0 C). Is possible.

  Furthermore, instead of uniquely reducing the charging current, as described with reference to FIG. 7, the voltage of the secondary battery 1 (battery cell) becomes a predetermined voltage (for example, 4) as the charging current is reduced. Of course, the current value may be reduced stepwise every time it reaches .20V / cell). In this case, for example, the current value may be limited to about 0.7 times the current value. Although an example in which a four-state control signal is output has been described here, it is of course possible to further subdivide the temperature range and further subdivide the terminal voltage range.

  In the above-described embodiment, the control terminal CHG is described as being pulled up by the resistors 9a and R. However, the present invention can be similarly applied to the case where the control terminal CHG is pulled down via the resistor. . Alternatively, it is of course possible to reverse the status output logic via the control terminal CHG, specifically the output voltage level. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

A, B pack battery C, D charger 1 secondary battery 2 voltage detection unit 3 current detection unit 4 thermistor (temperature detection means)
5 Charging Control Unit 5a Logic Circuit 5b Output Circuit 8 Power Supply Unit 9 Control Unit

Claims (7)

A secondary battery, a voltage detection means for detecting the terminal voltage of the secondary battery, a temperature detection means for detecting the temperature of the secondary battery, and the secondary battery detected by each of the detection means. A logic circuit that divides charging conditions for safely charging the secondary battery according to terminal voltage and temperature into a plurality of chargers, and a charger that charges the secondary battery according to the output of the logic circuit An output circuit that selectively provides control voltages at different voltage levels in a plurality of stages,
The logic circuit is predetermined according to a combination of a voltage region in which the terminal voltage of the secondary battery is divided into a plurality of stages in advance and a temperature region in which the chargeable temperature region of the secondary battery is divided into a plurality of stages in advance. One of the plurality of charging conditions is selected according to the terminal voltage and temperature of the secondary battery respectively detected by the detecting means.   The logic circuit is predetermined according to a combination of a voltage region in which the terminal voltage of the secondary battery is previously divided into three stages and a temperature region in which the secondary battery can be charged in two stages. 2. The battery pack according to claim 1, wherein one of the four charging conditions is selected according to a terminal voltage and a temperature of the secondary battery respectively detected by the detection means. The two rechargeable temperature regions of the secondary battery are a standard temperature region and a high temperature region,
The voltage threshold for dividing the three-stage voltage range is a standard recommended charging voltage in the standard temperature range and a high temperature recommended charging voltage in the high temperature range set lower than the standard recommended charging voltage,
The logic circuit is in a charge prohibition state in which charging of the secondary battery is prohibited when the temperature of the secondary battery is out of the standard temperature range and the high temperature range, the temperature of the secondary battery is in the standard temperature range, and When the terminal voltage of the secondary battery is equal to or higher than the standard recommended charging voltage, a current limiting state in which charging is permitted by limiting the charging current of the secondary battery, the temperature of the secondary battery is in the high temperature range, and When the terminal voltage of the secondary battery is equal to or higher than the high temperature recommended charging voltage, the charging voltage of the secondary battery is limited to allow charging, otherwise the recommended charging voltage in the corresponding temperature range is set. 3. The battery pack according to claim 2, wherein an output signal indicating a charge permission state permitting charging of the secondary battery is alternatively generated as the control signal.   The output signal is output as a voltage in which the voltage level of the logic circuit decreases stepwise in the order of the charging prohibited state, the charging permitted state, the voltage limited state, and the current limited state. The battery pack according to claim 3. The secondary battery is obtained by connecting a plurality of lithium ion batteries in series and parallel,
The battery pack according to claim 1, wherein the voltage detection unit detects a cell voltage of the lithium ion battery. The battery pack according to any one of claims 1 to 5 and a charger that is connected to the battery pack and charges the secondary battery,
The charging system includes a charging control unit that determines a level of a control voltage supplied from the battery pack and limits a charging voltage and / or a charging current applied to the secondary battery. The battery pack according to any one of claims 1 to 5 and a charger that is connected to the battery pack and charges the secondary battery,
The charger inputs a control voltage supplied from the battery pack as temperature information of the secondary battery, and the level of the control voltage is out of a voltage range defined by a preset upper limit voltage and lower limit voltage. The charging of the secondary battery is stopped when the temperature of the secondary battery is out of the temperature range in which the secondary battery can be charged,
The output circuit in the battery pack has a voltage range defined by the upper limit voltage and the lower limit voltage when the charge condition selected by the logic circuit is charge prohibition and / or when the charge current is limited. A charging system that outputs a control voltage at a voltage level that deviates.

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