JP4557569B2 - Battery pack - Google Patents

Description

  The present invention relates to a charging technique for charging an assembled battery having battery cells that require charging at a voltage equal to or lower than a predetermined reference voltage value.

An example of a charging technique for charging a lithium ion battery cell is disclosed in Japanese Patent Application Laid-Open No. 11-187588 (see Patent Document 1). As understood from such technology, when the constant current charging is continued, the voltage value of the battery cell rises beyond the usable voltage value, and various problems may occur. In general, charging is performed using a voltage-controlled charger. In many cases, the lithium ion battery cell is charged after the voltage value of the battery cell reaches a predetermined reference voltage value (a voltage value that can be reliably charged without deteriorating the quality of the battery cell). Constant voltage charging that is charged at this reference voltage value until the end of charging is applied.
On the other hand, battery cells such as nickel cadmium battery cells and nickel metal hydride battery cells have a flat charge voltage characteristic and a low rate of increase in the voltage value of the battery cells at the end of charging, so they are suitable for voltage control charging. In general, charging is performed using a current control type charger. In many cases, constant-current charging, in which charging is performed with a constant charging current from the start of charging to the end of charging, is applied to the charging of these nickel-based battery cells.
Japanese Patent Laid-Open No. 11-187588

Thus, when a charger with a different charging method is required depending on the type of battery cell constituting the assembled battery, when the user obtains a battery pack or device including the assembled battery, another charging method has already been established. Even if the charger is possessed, it is necessary to further obtain a charger for charging the assembled battery. Typically, the user charges a lithium ion battery cell or the like that requires charging at a voltage equal to or lower than a predetermined reference voltage value even if the user already has a current control type charger such as a constant current charger. Therefore, it is necessary to further obtain a voltage control type charger, and further technical exploration has been requested in terms of versatility of the charging technology.
This invention is made in view of this point, and provides the charging technique with high versatility which can charge the assembled battery which has a battery cell which requires the charge by the voltage below a predetermined reference voltage value. Is the purpose.

In order to achieve the above object, the invention described in each claim is configured.
According to invention of Claim 1, a battery pack provided with an assembled battery is comprised.
This “assembled battery” has one or a plurality of battery cells that require charging at a voltage equal to or lower than a predetermined reference voltage value.
As a battery cell that requires charging at a voltage below a predetermined reference voltage value, a secondary battery that causes various problems such as deterioration of the battery cell when the voltage value of the battery cell exceeds the usable voltage value during charging (charging is not possible. Batteries that can be used repeatedly and used repeatedly. Typically, a lithium ion battery cell or the like is used.
Note that the “predetermined reference voltage value” indicates a voltage value that can reliably complete the charging without impairing the quality of the battery cell when charging such a battery cell. Typically, in the case of a lithium ion battery cell, the voltage value is approximately 4.1 (V) or 4.2 (V) per battery cell, although it varies depending on the electrode material and the like. It is often used as.

  Moreover, as an assembled battery, the aspect comprised only with such a battery cell, the aspect which consists of such a battery cell, and a battery cell which does not need to be charged with the voltage below a predetermined reference voltage value, etc. are included altogether. . Moreover, the aspect comprised by the state comprised with the battery cell of the same kind (for example, only lithium ion battery cell) and the state where the battery cell of a different kind is mixed widely is included. Further, the battery cells in the assembled battery may be connected in series with each other or may be connected in parallel. Further, the specification of the output voltage of the battery pack (generally referred to as a nominal voltage) is determined by the type, number, connection mode, etc. of the battery cells constituting the battery pack. Typically, the nominal voltage of the assembled battery in which a plurality of battery cells are connected in series can be set as a value obtained by adding the nominal voltages of the battery cells.

When charging an assembled battery having one or a plurality of battery cells that are charged at a voltage equal to or lower than a predetermined reference voltage value, as described in the case of a lithium ion battery cell in the conventional technique, It is required that each battery cell which is a component of the assembled battery is charged so as not to exceed the reference voltage value.
The battery pack according to the present invention includes a “diversion device” in order to cope with such a request. When the charging current is supplied to the assembled battery and the battery is charged, the shunt device charges the assembled battery at a voltage equal to or lower than the predetermined charging voltage value when the voltage value of the assembled battery reaches a predetermined charging voltage value. The charging current of the assembled battery is shunted as described above.
Here, “dividing the charging current” means that the charging current supplied from the charger to the assembled battery is divided into one or a plurality of currents.
The “predetermined charging voltage value” in the present invention is typically determined based on the above-described reference voltage value of the battery cells constituting the assembled battery. For example, if the assembled battery is configured by connecting three lithium ion battery cells in series and the reference voltage values of the lithium ion battery cells are 4.1 (V), respectively, 4.1 (V ) Multiplied by 3 to determine 12.3 (V) as the “predetermined charging voltage value” of the battery pack.

  Further, the “voltage below a predetermined charging voltage value” includes all voltages that can complete the charging of the assembled battery and are below the “predetermined charging voltage value”. Typically, the “voltage below the predetermined charging voltage value” is a voltage value within the range of the “predetermined charging voltage value” and its error, or will be described later in detail. A decrease in voltage value generated for the purpose of detecting the completion of charging (full charge voltage decrease value “ΔV” of full charge voltage decrease “−ΔV” described later) is subtracted from the “predetermined charge voltage value”. The case where the voltage is in the range up to the voltage value is shown.

  In the present invention, as an aspect in which the assembled battery is charged with “a voltage equal to or lower than a predetermined charging voltage value”, a current value to be shunted among charging currents supplied to the assembled battery is appropriately determined using a shunt device. An aspect in which the voltage value of the assembled battery is set to a predetermined charging voltage value or less, and an aspect in which the voltage value of the assembled battery is set to a predetermined charging voltage value or less by appropriately determining the timing and time for diverting the charging current using the shunt device Etc. are widely included. Typically, the shunt device is provided with an impedance circuit that can be connected in parallel to the assembled battery. When the voltage value of the assembled battery reaches a predetermined charging voltage value, a part of the charging current is shunted to the impedance circuit. It is configured to be. In this case, it is preferable that the impedance value of the impedance circuit is variable and the amount of charging current shunted to the circuit is set to be adjustable.

  In addition, as the time when the shunting of the charging current for charging the assembled battery is started, when the assembled battery reaches a predetermined charging voltage value, the assembled battery reaches the predetermined charging voltage value within a set time (soon after the predetermined charging voltage value). All the points in time when the charging voltage value is reached are included. In addition, the period during which the charging current for charging the assembled battery is shunted is the entire period from when the assembled battery reaches the predetermined charging voltage value until the charging is completed, and when the assembled battery reaches the predetermined charging voltage value. This includes a wide range of cases such as a predetermined period from charging to completion of charging. When the period during which the charging current for charging the assembled battery is shunted is the above-mentioned part of the predetermined period, the number of times the charging current is shunted is set so that the voltage value of the assembled battery is equal to the predetermined charging voltage value. It may be once or a plurality of times throughout the period from when the battery is reached to when the charging is completed.

  According to the battery pack of the present invention, an assembled battery having one or a plurality of battery cells that require charging at a voltage equal to or lower than a predetermined reference voltage value can be reliably lower than a predetermined charging voltage value without deteriorating the quality of the assembled battery. It became possible to charge with the voltage of. Therefore, if the user already possesses a current control type charger such as a constant current charger, in order to charge an assembled battery having a battery cell that requires charging at a voltage equal to or lower than a predetermined reference voltage value. Therefore, it is not necessary to further obtain a voltage control type charger, and it becomes possible to rationalize and generalize the charging equipment.

  In particular, various types of assembled batteries having different specifications such as 9.6 V, 12 V, 14.4 V, 18 V, and 24 V are used for devices such as electric tools. In particular, battery packs for power tools are generally used in a situation where the battery consumption is large, and the charger is used while being repeatedly charged at a suitable frequency, so that quick and easy charging is required. Often done. If the battery pack of the present invention is used, the user need not consider whether or not the assembled battery has a battery cell that requires charging at a voltage equal to or lower than a predetermined reference voltage value. Charging can be performed using a container. Of course, since the battery pack of the present invention can be charged even by a voltage control type charger described in the prior art, it is also suitable for a battery pack of an electric tool that requires quick and easy charging. Applied.

(Invention of Claim 2)
According to the second aspect of the present invention, the battery pack according to the first aspect is configured such that when the assembled battery is charged with a constant current using a constant current charger, the voltage of the battery cell is equal to or lower than a predetermined reference voltage value. The charging current of the assembled battery is shunted using a shunt device so that the battery is charged with
The “constant current charger” in the present invention broadly includes chargers that charge a battery pack by supplying a charging current having a constant current value to the battery pack. The “constant current charger” is typically widely used as a current control type charger that supplies a charging current to a nickel-based battery cell or the like.

On the other hand, conventionally, when charging a battery cell that requires charging at a voltage equal to or lower than a predetermined reference voltage value, as described in the case of the lithium ion battery cell in the conventional technique, the voltage value of the battery cell is After reaching a predetermined reference voltage value, a constant voltage charger that is charged at this reference voltage value until the end of charging is used. If a constant current value charging current is supplied to such a battery cell using the constant current charger, the voltage value of the battery cell rises beyond the usable voltage value, and various problems may occur. there were.
Therefore, in the battery pack of the present invention, when the assembled battery is charged with a constant current using a constant current charger, a shunt device is used so that the battery cell is charged with a voltage equal to or lower than a predetermined reference voltage value. Thus, the charging current of the assembled battery is shunted, so that it is possible to charge a battery cell that requires charging at a voltage equal to or lower than a predetermined reference voltage value using a constant current charger.

(Invention of Claim 3)
According to a third aspect of the present invention, in the battery pack according to the first or second aspect, the shunt device includes a voltage detection means for detecting a voltage value of the assembled battery, and a battery pack based on the voltage value of the assembled battery. And control means for determining an amount of diverting a charging current for charging the battery.
The “control unit” is typically configured using a CPU and a storage unit such as a ROM. The storage means preferably stores in advance a program for determining an amount (Ah) for diverting a charging current for charging the assembled battery from the voltage value of the assembled battery. The amount (Ah) for diverting the charging current widely includes an aspect for changing the current value (A), an aspect for changing the time (h) for diverting, and the like. Typically, this shunting device is provided with an impedance circuit connected in parallel to the assembled battery. Then, the control means of the shunt device determines the impedance value of the impedance circuit using the voltage detection value of the assembled battery by the voltage detection means based on the above-mentioned program stored in the storage means, and shunts the impedance circuit Adjust the current value (A) of the charging current. The impedance circuit is provided with switching means such as a plurality of resistance elements and switching elements. The CPU of the control means performs on / off control of the switching element based on the determined impedance value at an appropriate timing, and sets the impedance circuit to the determined impedance value. Of course, the smaller the impedance value of the impedance circuit, the larger the current value shunted to the impedance circuit. Therefore, when the voltage value of the assembled battery is likely to exceed a predetermined charging voltage value, it is preferable to reduce the impedance value. . The storage means may be composed of a member different from the control means.
According to the battery pack of the present invention, when the assembled battery is charged, it becomes easy to shunt the charging current so that the voltage value of the assembled battery is charged at a voltage value equal to or lower than a predetermined charging voltage value. .

(Invention of Claim 4)
According to the invention of claim 4, the battery pack of the battery pack of claim 3 is charged by using a charger capable of detecting a full charge voltage drop when the battery pack being charged is fully charged. When supplying the current, the control means, when the assembled battery is fully charged after the assembled battery voltage value reaches a predetermined charging voltage value, the voltage value of the assembled battery is detected by the charger. The amount by which the charging current is shunted is determined so as to be a predetermined voltage value when the charging voltage drop occurs.

  In general, a charger has a function of detecting a full charge of an assembled battery by various methods during charging and stopping the charging. The charger described in the present invention is configured to detect a full charge voltage drop when the assembled battery is fully charged. Such a full charge detection method is frequently used in constant current chargers for charging nickel / cadmium battery cells or nickel / hydrogen battery cells. These battery cells have a characteristic that the voltage value per cell decreases by about 5 to 20 mA from the peak value at the end of charging. This decrease in voltage value is generally referred to as “−ΔV”, and a method for detecting the full charge of a battery cell by such a method is generally referred to as a “−ΔV method”. In the case of an assembled battery in which a plurality of battery cells are connected in series, the battery cell that constitutes the assembled battery at “full charge voltage drop” per cell as “full charge voltage drop” (−ΔV) of the battery pack The value multiplied by the number of is set.

At this time, the control unit of the shunt device typically predicts the voltage value of the assembled battery at the time when the assembled battery is fully charged after the voltage value of the assembled battery reaches a predetermined charging voltage value. When the battery is fully charged, the charge current of the battery pack is shunted so that the voltage value of the battery pack becomes the above-mentioned “predetermined voltage value when a full charge voltage drop detectable by the charger occurs”. Determine the amount. As a method of predicting the voltage value at the time when the assembled battery is fully charged, a method of predicting based on the charge amount of the assembled battery at that time (for example, it can be obtained based on the voltage value of the assembled battery). Is preferably applied.
Thereby, when the assembled battery is fully charged, the charger can detect a decrease in the fully charged voltage and stop charging the assembled battery.
That is, when the battery pack of the present invention is used, when the battery pack of the battery pack is fully charged, the voltage value of the battery pack can be reduced as if a full charge drop has occurred. Thereby, the above-mentioned charger can be made to detect full charge of an assembled battery, and the charger can stop charge of an assembled battery. Therefore, when the assembled battery is fully charged, charging is reliably stopped.

  According to the present invention, a highly versatile charging technique capable of charging an assembled battery having battery cells that require charging at a voltage equal to or lower than a predetermined reference voltage value is provided.

(First embodiment)
An example of the best mode for carrying out the present invention will be described below with reference to FIGS. 1 to 3 and FIG. In the present embodiment, as an example, the battery pack 100 according to the present invention has lithium ion battery cells that require charging at a voltage equal to or lower than a predetermined reference voltage value, and a constant current charger is used for the battery pack 100. A case where a charging current having a constant current value is supplied will be described. FIG. 1 schematically shows a configuration of a battery pack 100 according to the present invention in a block diagram. FIG. 1 also shows a schematic configuration of an example of a charger 200 that charges the battery pack 100. In FIG. 2, the voltage value of the assembled battery of the battery pack 100 and the change of charging current are shown with time. FIG. 3 shows a flowchart of a program executed by the control unit of the battery pack 100 when charging the assembled battery. FIG. 5 shows a conventional technique for charging a nickel-based assembled battery using the charger 200.

First, the configuration of the battery pack 100 will be described with reference to FIG.
The battery pack 100 includes an assembled battery 110, a shunt device 300, a circuit configuration for charging the assembled battery 110 using external devices such as the charger 200, and an assembled battery when devices such as an electric tool are connected. A circuit configuration for discharging 110 (that is, for consuming the assembled battery 110), and a print on which terminals TE1 to TE3 that can be connected to corresponding terminals of devices such as the charger 200 and the power tool are mounted A substrate. Although not shown, the battery pack 100 includes a housing that accommodates the assembled battery 110 and a printed board, and is configured to be detachable from devices such as a charger 200 and a power tool. When battery pack 100 is attached to charger 200, terminals TE <b> 1 to TE <b> 3 of battery pack 100 are connected to terminals TE <b> 11 to TE <b> 3 of corresponding charger 200, and assembled battery of battery pack 100 using charger 200 is used. 110 can be charged. On the other hand, although not shown, when the battery pack 100 is attached to a device such as an electric tool, the terminals TE1 to TE3 of the battery pack 100 are connected to the corresponding device terminals, and the assembled battery 110 of the battery pack 100 is used. The device can be supplied with power.

As the assembled battery 110 housed in the casing of the battery pack 100 described above, a lithium ion battery group in which three lithium ion battery cells are connected in series is provided. Various circuit configurations mounted on the printed circuit board include a battery control unit 130 that has a CPU and controls the operation of the battery pack 100, and terminals TE1 to TE3 that connect the charger 200 or the battery pack 100 after charging to a device. The battery control unit 130 includes an impedance circuit Z whose impedance value is changed.
This lithium ion battery group (the assembled battery 110) corresponds to the “assembled battery” in the present invention, and the lithium ion battery cell corresponds to the “battery cell that requires charging at a voltage equal to or lower than a predetermined reference voltage” in the present invention. It is an element to do. Further, the impedance circuit Z and the battery control unit 130 are elements corresponding to the “shunt device” in the present invention.

  The plus side (upper side shown in FIG. 1) of the assembled battery 110 is connected to the terminal TE1 of the battery pack 100, and the minus side (lower side shown in FIG. 1) of the assembled battery 110 is connected to the terminal TE2 of the battery pack 100. . When the battery pack 100 is attached to the charger 200, the terminals TE1 and TE2 are connected to terminals TE11 and TE12 of the charger 200 described later, respectively, so that the assembled battery 110 is charged. Further, when the battery pack 100 is attached to a device such as an electric tool, the terminals TE1 and TE2 are connected to corresponding terminals of the device, and the assembled battery 110 is discharged to supply power to the device. Yes.

Further, one end of the impedance circuit Z is connected to the plus side of the assembled battery 110. The other end of the impedance circuit Z is connected to the negative side of the battery pack 110.
Further, the plus side of the assembled battery 110 is further connected to the terminal 131 of the battery control unit 130, and the minus side of the assembled battery 110 is further connected to the terminal 132 of the battery control unit 130. Thereby, the terminal TE1, the plus side of the assembled battery 110, one end of the impedance circuit Z, and the terminal 131 of the battery control unit 130 are connected. Further, the terminal TE2, the negative side of the assembled battery 110, the other end of the impedance circuit Z, and the terminal 132 of the battery control unit 130 are connected.
With this configuration, the battery control unit 130 detects the potential difference between the terminal 131 and the terminal 132 at an appropriate timing, and calculates the voltage value of the assembled battery 110.
The battery control unit 130 has a storage unit, and a program for determining the impedance value of the impedance circuit Z based on the voltage value of the assembled battery 110 is stored in the storage unit in advance. Thereby, the battery control unit 130 can change the impedance value of the impedance circuit Z.
The voltage value of the assembled battery 110 calculated in this way corresponds to the “voltage value of the assembled voltage” of the present invention. Further, a circuit configuration for detecting the voltage value of the assembled battery 110 (a circuit configuration for detecting a potential difference between the terminal 131 and the terminal 132), and a predetermined value for detecting the voltage value of the assembled battery 110 among programs executed by the battery control unit 130. These steps (step S10 and step S19 of the program shown in FIG. 3 described later) correspond to the “voltage detection means” of the present invention.

  The battery control unit 130 preferably operates using the assembled battery 110 as a power source, but charging means for operating the battery control unit 130 is provided. The battery control unit 130 may be configured to operate by being charged. Moreover, it is good also as a structure from which the control power supply for battery control part 130 operation | movement is output from the charger 200. FIG. In this case, a terminal for control power output is provided on the charger 200 side, and a terminal for control power input is provided on the battery pack 100.

  Further, the terminal TE3 is connected to the terminal 133 of the battery control unit 130. As a result, the charge control unit 220 of the charger 200 receives a voltage having a predetermined value less than the set voltage value Vs or a voltage having a predetermined value greater than or equal to the set voltage value Vs, which will be described in detail later. It is input from.

Next, an outline of the configuration of the charger 200 that charges the battery pack 100 will be described.
In the present embodiment, a case where charger 200 is a constant current charger that supplies a charging current having a constant current value during a charging period of battery pack 110 will be described.
The charger 200 includes a power supply circuit 210 that converts AC input power to a DC power supply for charging the battery pack 100, a charge control unit 220 that controls the power supply circuit 210, terminals TE11 to TE13 for connection to the battery pack 100, AC Input terminals SE11 and SE12 for connecting an input power supply are provided.

The input side of the power supply circuit 210 is connected to input terminals SE11 and SE12 to which an AC input power supply can be connected. The power supply output terminal of the power supply circuit 210 is connected to the output terminal TE11 of a DC power supply that is converted from the AC input power supply by the power supply circuit 210 and charges the battery pack 100 under the control of the charging control unit 220. The ground terminal of the power supply circuit 210 is connected to the output terminal TE12 via a shunt resistor. Thereby, in the charger 200 shown in FIG. 1, the output terminal TE11 is a power supply terminal, and the output terminal TE12 is a ground potential supply terminal.
Although not particularly shown, the power supply circuit 210 outputs a control power supply (generally 5 V) converted from an AC input power supply and supplied to an IC or the like in the charger 200, and the charge control unit 220 or the like. Has been supplied to.
Further, the terminal TE12 and one end of the shunt resistor are connected to the charging control unit 220, and the charger 200 has a configuration capable of detecting a charging current value by this configuration.
In addition, the charging control unit 220 is connected to the terminal TE13, whereby a voltage having a predetermined value less than the set voltage value Vs or greater than the set voltage value Vs, which will be described in detail later, from the battery control unit 130 of the battery pack 100. A predetermined voltage is input.

Next, the operation of charging the battery pack 100 (that is, the assembled battery 110) with the charger 200 will be described with reference to FIGS.
FIG. 2 shows changes in voltage value and charging current of the assembled battery 110 over time when the assembled battery 110 of the battery pack 100 of the present embodiment is charged by the charger 200. FIG. 3 is a flowchart of a program executed by the battery control unit 130 of the battery pack 100 according to the present embodiment when the assembled battery 110 is charged.

  First, an AC input power source is connected to the input terminals SE11 and SE12 of the charger 200 (see also FIG. 1). As a result, the control power obtained by converting the AC input power by the power supply circuit 210 is supplied to the charge control unit 220 in the charger 200 (not particularly shown), whereby the charger 200 starts operation.

When the battery pack 100 is attached to the charger 200, the terminals TE11 to TE13 of the charger 200 are connected to the terminals TE1 to TE3 of the battery pack 100, respectively.
By being connected in this way, the charging control unit 220 of the charger 200 controls the power supply circuit 210 to output a charging current having a constant current value. In this way, charging of the assembled battery 110 of the battery pack 100 is started.
In the initial state where charging is started, the impedance value of the impedance circuit Z of the battery pack 100 is set to ∞ (infinite) (the impedance circuit Z is disconnected).

  And the battery control part 130 of the battery pack 100 detects the voltage value of the assembled battery 110 at a predetermined timing, as shown in step S10 of FIG. As described above, the voltage value of the assembled battery 110 can be detected from the potential difference between the terminals 131 and 132 of the battery control unit 130. Then, the battery control unit 130 proceeds to the process of step S12.

In step S12, it is determined whether or not the voltage value of the assembled battery 110 detected in step S10 is equal to or greater than a preset constant voltage setting value S (V). When the voltage is less than the constant voltage set value S (V), the battery control unit 130 returns and continues charging in the state as it is (time t0 to t1 shown in FIG. 2). On the other hand, when the voltage value of the assembled battery 110 is equal to or higher than the constant voltage set value S (V) (time t1 shown in FIG. 2), the battery control unit 130 proceeds to the process of step S14.
Here, as the constant voltage set value S (V), a voltage value at which the assembled battery 110 can finish charging without losing its quality is set in the battery control unit 130 in advance. Since the assembled battery 110 according to the present embodiment is composed of three lithium ion battery cells, it corresponds to a constant voltage setting value (the “predetermined reference voltage” of the present invention) of this one lithium ion battery cell. ) Is 4.1 (V), the constant voltage set value S (V) of the battery pack 110 (corresponding to the “predetermined charging voltage value” of the present invention) is 12.3 (V) (12 .3 (V) = 4.1 (V) × 3).

In step S <b> 14, when a timer of “timer function” described later of battery control unit 130 is in an off state, the timer is started. Then, the battery control unit 130 proceeds to the process of step 16.
Here, the “timer function” measures the time from when the voltage value of the assembled battery 110 reaches the constant voltage setting value S (V) (time t1 shown in FIG. 2) until the charging of the assembled battery 110 is completed. To do. In the battery control unit 130, a set value ts (seconds) is set in advance as a time for the assembled battery 110 to be fully charged.

  In step S <b> 16, the battery control unit 130 determines the impedance value of the impedance circuit Z. In the storage unit of the battery control unit 130, a plurality of impedance values corresponding to the difference between the constant voltage set value S (V) and the detected voltage value are stored in advance. For example, when the detected voltage value of the assembled battery 110 is equal to or exceeds the constant voltage set value S (V), an impedance value smaller than the currently selected impedance value is selected. Further, when the detected voltage value of the assembled battery 110 is likely to fall below the constant voltage set value S (V) by a predetermined threshold value or more, an impedance value larger than the currently selected impedance value is selected. As the impedance value selection condition, data such as a voltage value at that time and a change rate of the voltage value are appropriately used. Then, the impedance value of the impedance circuit Z is set to a selected impedance value by, for example, controlling on / off of switching elements that connect a plurality of resistance elements included in the impedance circuit Z (that is, after charging is started) When the answer in step S12 is “Yes” for the first time, the impedance value is changed from the initial value ∞ (infinity) to the impedance value selected by the battery control unit 130. Then, the battery control unit 130 proceeds to the process of step S18.

In step S18, it is determined whether or not the timer value of the “timer function” is equal to or greater than a set value ts (seconds). If it is less than the set value ts (seconds), the battery control unit 130 proceeds to the process of step S19, and if it is equal to or greater than the set value ts (seconds), the process proceeds to step S20.
In step S19, the battery control unit 130 detects the voltage value of the assembled battery 110 and returns to the process of step S16.
On the other hand, in step S20, the timer function timer is turned off, and the timer value is cleared. Then, the battery control unit 130 proceeds to the process of step S22.
In this way, at times t1 to t3 (between time t1 and after the set value ts (seconds) has elapsed) shown in FIG. The value is updated as appropriate, and until the set value ts (seconds) elapses after reaching the constant voltage set value S (V) at time t1, the constant voltage set value S (V) (constant voltage set value S (V) To within a predetermined voltage value range).
In step S <b> 22, the battery control unit 130 outputs “a voltage having a predetermined value less than the set voltage value Vs”, which will be described in detail later, from the terminal 135.

Here, the details of the “voltage having a predetermined value less than the predetermined voltage value Vs” output in step S22 will be described.
Here, generally, the charger 200 receives a temperature index output signal corresponding to the temperature of the assembled battery being charged, and the temperature of the assembled battery is equal to or higher than a predetermined temperature by the control unit based on the temperature index output signal. If it is determined that the battery is charged, a function for stopping charging of the assembled battery may be provided.
For example, in the conventional battery pack 100a shown in FIG. 5, the thermistor TM is provided in the vicinity of the nickel-based battery group 110a. The charging control unit 220 of the charger 200 is configured to be able to detect the voltage value (the temperature index output signal described above) at both ends of the thermistor TM via the terminal 13. When the thermistor TM is an NTC thermistor, the thermistor TM has a characteristic that the impedance value decreases as the temperature rises. Thereby, the charge control part 220 can monitor whether the temperature of the assembled battery 110 in which the thermistor TM is arrange | positioned in the vicinity is less than preset temperature from the voltage value of the both ends of the thermistor TM. In the charger 200 of the present embodiment, if the voltage value at both ends of the thermistor TM is equal to or higher than the set voltage value Vs, it is determined that the assembled battery 110a is not in a high temperature state, and the charging operation to the assembled battery 110a can be continued. To do. On the other hand, if the voltage value at both ends of the thermistor TM is less than the set voltage value Vs, it is determined that the assembled battery 110a is in a high temperature state, and the charging operation to the assembled battery 110a is stopped.
The battery control unit 130 of the battery pack 100 of the present embodiment shown in FIG. 1 is provided with a function of detecting the voltage value at both ends of the thermistor TM as described above when charging of the assembled battery 110 is completed. A voltage at which the assembled battery 110 of the battery pack 100 is determined to be in a high temperature state by the charging control unit 220 of 200, that is, a predetermined voltage less than the set voltage value Vs is applied to the terminal 133, the terminal TE3 of the battery pack 100, The data is output to the charging control unit 220 via the terminal TE13 of 200.
Thereby, the charging control unit 220 of the charger 200 capable of detecting the voltage value at both ends of the thermistor TM can determine that the assembled battery 110 is in a high temperature state and stop the charging of the battery pack 100.

  In this way, when the assembled battery 110 of the battery pack 100 is charged using the charger 200, as shown in FIG. 2, the voltage value of the assembled battery 110 is changed at an appropriate timing after starting charging at time t0. It is detected (corresponding to the process of step S10 shown in FIG. 3). At time t0 to t1, since the voltage value of the assembled battery 110 has not reached the constant voltage set value S (V) (No in step S12 shown in FIG. 3), the impedance circuit Z is disconnected and charged. All the charging current by the battery 200 flows to the assembled battery 110 side.

  When it is determined that the voltage value of the assembled battery 110 has reached the constant voltage set value S (V) at time t1 (Yes in the process of step S12 shown in FIG. 3), the battery control unit 130 determines the voltage value. The impedance circuit Z set to the impedance value (the process of step S16 shown in FIG. 3) is connected in parallel to the assembled battery 110. At the same time, the battery control unit 130 starts a timer for detecting the end of charging (processing in step S14 shown in FIG. 3). After time t1, the voltage value of the assembled battery 110 is detected at an appropriate timing (corresponding to step S19 shown in FIG. 3), and the impedance value is set so that the voltage value of the assembled battery 110 is the constant voltage set value S (V). The battery pack 110 is updated (corresponding to step S16), and charging of the battery pack 110 is continued while the charging current is shunted to the impedance circuit Z based on the updated impedance value.

As a result, the battery pack 110 is charged approximately at the constant voltage set value S (V) from the time t1 when the voltage value of the assembled battery 110 first reaches the constant voltage set value S (V) until the set value ts (seconds) has elapsed. The For example, at time t2 shown in FIG. 2, out of the charging current I (A), the current Ia (A) flows through the impedance circuit Z and the current Ib (A) flows through the assembled battery 110 (charging current I (A ) = Ia (A) + Ib (A)). In this state, the voltage value of the assembled battery 110 is generally maintained at a constant voltage set value S (V).
When it is detected at time t3 that the value of the timer has reached the predetermined value ts (corresponding to step S18 shown in FIG. 3), the battery control unit 130 informs the charger 200 that the “set voltage value Vs described above. A voltage having a predetermined value less than "is output (corresponding to step S22).
Thereby, the charging control part 220 of the charger 200 detects that the charging of the assembled battery 110 of the battery pack 100 is completed, and ends the charging.

  As described above, in the battery pack 100 of the present embodiment, the assembled battery 110 that needs to be charged at a voltage equal to or lower than the constant voltage setting value S (V) is charged with the charging current having a constant charging current value I (A). Using the charger 200 that performs the charging, the battery can be reliably charged with a voltage equal to or lower than the constant voltage set value S (V). That is, it is not necessary to separately prepare a charger for charging the assembled battery 110 that needs to be charged at a voltage equal to or lower than the constant voltage set value S (V). Thus, the battery pack 100 having versatility when charging the assembled battery 110 is provided.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG.
In the present embodiment, the charger 200 (refer to FIG. 1 together) has a function of detecting the full charge of the assembled battery by the so-called “−ΔV method”. A case where the amount of charging current for charging the assembled battery is adjusted so that the full charge of the assembled battery can be detected by the “−ΔV method” will be described.
The charging control unit 220 of the charger 200 of the second embodiment stops charging by detecting a predetermined full charge voltage drop (“−ΔV”) after the voltage value of the assembled battery reaches the peak value. The full charge voltage drop (“−ΔV”) may be set in any way as long as it is a unit of several mV to several tens of mV. Although not particularly illustrated, in the battery pack of the second embodiment, the assembled battery 110 is completely charged as in the battery pack 100 described in the first embodiment (see also FIG. 1). 1 is configured to output “a voltage having a predetermined value less than the set voltage value Vs”, that is, the terminal TE3 shown in FIG. 1, the connection circuit to the terminal 133 of the terminal TE3 and the battery controller 130, and the steps shown in FIG. It is not necessary to provide the process of S22.
Furthermore, in the battery pack of the second embodiment, after the assembled battery first reaches the constant voltage set value S (V), a method of updating the impedance value of the impedance circuit Z (shown in FIG. Corresponds to step S16 of the program executed in the battery pack 100 of the embodiment.) Is different from the case of the battery pack 100.
Other configurations of the battery pack of the second embodiment are the same as those of the battery pack 100 of the first embodiment (refer to FIG. 1 together).

The operation of charging such a battery pack with the charger 200 will be described with reference to FIG. In FIG. 4, the change of the voltage value of the assembled battery and the change of the charging current when charging the assembled battery of the second embodiment with the charger 200 are shown with time.
When the assembled battery of the battery pack according to the second embodiment is charged using the charger 200, the voltage value of the assembled battery is detected at an appropriate timing after charging is started at time t0. At time t0 to t1, since the voltage value of the assembled battery does not reach the constant voltage set value S (V), the impedance circuit Z is disconnected, and the charging current of the charger 200 is all on the assembled battery side. Flowing.

When it is determined that the voltage value of the assembled battery has reached the constant voltage set value S (V) at time t1, the impedance circuit Z set to the impedance value determined by the battery control unit is parallel to the assembled battery. Connected. At the same time, the battery control unit starts a timer similar to the “timer function” in the first embodiment (also refer to step S14 in the first embodiment shown in FIG. 3).
Then, while detecting the voltage value of the assembled battery at an appropriate timing from the time t1 when the voltage value of the assembled battery reaches the constant voltage set value S (V) to the time when the set value ts (seconds) has elapsed, the assembled battery When the set value ts (seconds) at which the battery is fully charged has elapsed (corresponding to “when the battery is fully charged after the voltage value of the battery reaches the predetermined charging voltage value” in the present invention). , The impedance value of the impedance circuit Z is updated so that ΔV (V) decreases from the constant voltage set value S (V). The above-described processing executed by the battery control unit corresponds to the processing in step S16 in the case of the first embodiment shown in FIG.
Then, the voltage value of the assembled battery is detected at an appropriate timing (corresponding to the process of step S19 shown in FIG. 3), and based on the voltage value at that time, the assembled battery at the time when the set value ts (seconds) has elapsed. While predicting the voltage value, when the set value ts (seconds) has elapsed, the impedance value of the impedance circuit Z is corrected so that the voltage value of the assembled battery decreases by ΔV (V) from the constant voltage set value S (V), Update. (This corresponds to the processing in steps S16 to S19 shown in FIG. 3.)
When the charging of the assembled battery is completed after the set value ts (seconds) has elapsed, the voltage value of the assembled battery decreases by ΔV (V) from the constant voltage set value S (V) at time t3. Thus, the charger that can detect the full charge of the battery pack detects the full charge of the battery pack and stops charging.

  According to the battery pack of the present embodiment, when the assembled battery of the battery pack is fully charged, there is no need to output “a voltage having a predetermined value less than the set voltage Vs”, and the conventional “ The charger 200 that detects full charge by the “−ΔV method” can detect full charge of the assembled battery. Thereby, the versatility of the battery pack at the time of charge improves.

  In the battery packs of the first and second embodiments, the impedance value of the impedance circuit Z is configured to be changeable by the battery control unit, but the assembled battery can be charged at a constant voltage set value S (V) or less. If possible, the impedance value may be fixed. If the impedance value of the impedance circuit is fixed, the process of the battery control unit 130 is easy. In this case, the charge current amount (Ah) supplied to the assembled battery is changed by changing the ratio of the time when the impedance circuit is connected to the assembled battery and the time when the impedance circuit is disconnected. It is preferable.

  The impedance circuit Z may be any circuit that can shunt a part of the charging current for charging the assembled battery with a constant current. For example, an IC or the like that realizes such a function is provided as the impedance circuit Z. It may be done. As described above, if the impedance circuit Z is configured using an IC or the like, the number of parts may be small, so that the number of assembling steps of the flow dividing device is reduced.

  In the embodiment, the timer function is started when the voltage value of the assembled battery first reaches the constant voltage set value S (V) during charging. The start point of the timer function is the embodiment. It is not limited to this, and it is only necessary to measure the time until the end of charging of the battery pack. For example, a method in which the battery control unit 130 starts a timer function at the start of charging may be used.

  Further, as a method for causing the charger 200 to stop charging the assembled battery 100, 100a with respect to the full charge of the assembled battery 100, 100a, in the first embodiment, the battery control unit 130 of the battery pack 100 causes the assembled battery 100 to The case where a voltage indicating a high temperature state (a voltage having a predetermined value less than the set voltage value Vs) is output to the charger 200 has been described. In the second embodiment, the voltage value of the assembled battery 100a is decreased from the peak value during charging as if the fully charged voltage drop (−ΔV) occurred at the time when the assembled battery 100a is fully charged. The case of making it explained was explained. However, as a method for causing the charger 200 to stop the charging of the assembled batteries 100 and 100a, other methods may be used as long as the function of the charger 200 can be used.

A schematic configuration of a battery pack 100 according to a first embodiment is shown in a block diagram. The time-dependent change of the voltage value and charging current at the time of charging the assembled battery 110 which the battery pack 100 has is shown. When the assembled battery 110 of the battery pack 100 is charged with a constant current, the program executed by the battery control unit 130 for charging with the constant voltage set value S (V) while updating the impedance value of the impedance circuit Z Each process is shown in a flowchart. The voltage value at the time of charging the assembled battery which the battery pack of 2nd Embodiment has and the change with time of charging current are shown. In order to explain “a voltage having a predetermined value less than the set voltage value Vs” output from the terminal 133 of the battery control unit 130 of the first embodiment, a temperature index output signal of the conventional thermistor TM is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Battery pack 110 Battery pack 130 Battery control part 200 Charger 300 Shunt device S Constant voltage setting value (V)
Z impedance circuit

Claims (4)

A battery pack comprising an assembled battery having one or more battery cells that require charging at a voltage equal to or lower than a predetermined reference voltage value,
When the charging current is supplied to the assembled battery and charged, the assembled battery is charged at a voltage equal to or lower than the predetermined charging voltage value when the voltage value of the assembled battery reaches a predetermined charging voltage value. A battery pack having a shunt device for shunting the charging current of the assembled battery. The battery pack according to claim 1,
When the battery pack is charged at a constant current using a constant current charger, the battery pack is charged using the shunt device so that the battery cell is charged at a voltage equal to or lower than the predetermined reference voltage value. Battery pack that shunts current. The battery pack according to claim 1 or 2,
The shunt device includes a voltage detecting means for detecting a voltage value of the assembled battery, and a control means for determining an amount of dividing a charging current for charging the assembled battery based on the voltage value of the assembled battery. pack. The battery pack according to claim 3,
When supplying a charging current to the assembled battery using a charger capable of detecting a full charge voltage drop when the assembled battery is fully charged,
When the battery pack is fully charged after the voltage value of the battery pack reaches the predetermined charging voltage value, the control means is configured to detect the battery pack voltage value that can be detected by the charger. A battery pack that determines an amount of shunting a charging current so as to be a predetermined voltage value when a charging voltage drop occurs.

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