Battery pack and charging system

Abstract

The present invention provides a battery pack and a charging system, which can suppress the situation where the charging stop function is activated due to the increase in the battery cell voltage caused by the increase in the charging current, and can also shorten the charging time. A battery pack of one embodiment of the present invention comprises: a battery cell, a storage unit, a target current calculation unit, and an information notification unit. The storage unit is used to store the maximum current change. The maximum current change is the maximum value of the change in the charging current during charging control. The target current calculation unit calculates the control target value of the charging current supplied to the battery cell, that is, the target current value. The target current calculation unit calculates the value obtained by adding the maximum current change to the target current value at the time of the previous calculation as the new target current value. The information notification unit notifies the charger of the charging condition information including the new target current value. The maximum current change is determined according to the characteristics of the battery pack.

Description

Technical Field

[0001] The invention relates to a storage battery pack and a charging system. Background Art

[0002] A charging system including a battery pack and a charger is known. The battery pack includes a battery cell that is charged by a charging current from the charger. The charger is configured so that an output current output as a charging current gradually increases by a certain amount (for example, a predetermined maximum current change amount) over time, and is also capable of executing a control process for controlling the charging current to a target current value (Patent Document 1).

[0003] The charging system also has a charging stop function for stopping charging when the voltage of a battery cell (hereinafter also referred to as battery cell voltage) exceeds a predetermined allowable upper limit value in order to prevent damage to the battery pack.

[0004] In addition, a charger has been proposed which is not limited to a configuration corresponding to a single type of storage battery pack but can be connected to multiple types of storage battery packs. Such a charger can be used in various occasions where multiple types of storage battery packs can be charged.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 3972930 Summary of the invention

[0008] However, when using a charger corresponding to multiple types of battery packs, the battery cell voltage may increase too much as the charging current based on the charger increases, depending on the type of battery pack being charged. If the battery cell voltage exceeds the allowable upper limit, the charging stop function will operate.

[0009] In addition, as a battery pack, there are multiple types of battery packs with different electrical characteristics of battery cells (for example, internal resistance value of battery cells, charging capacity of battery cells, etc.). Moreover, in a battery pack with a larger internal resistance value of battery cells, the increase in the battery cell voltage relative to the unit change of charging current (for example, the increase in the maximum current change) becomes larger than that of a battery pack with a smaller internal resistance value of battery cells. Therefore, even if the battery pack with a larger internal resistance value of battery cells is not fully charged, its charge stop function may be operated as described above, so that the battery pack stops charging when it is not fully charged. Such a state is also called premature charge stop, for example.

[0010] In this regard, by setting the maximum current variation to be small, it is possible to suppress the above-mentioned charge stop function from operating even in a battery pack with a large internal resistance value. However, when the maximum current variation is set to be small, since the increase in the charging current in one current change becomes small, the time until the charging current reaches the target value will be longer, which may result in a longer charging time until the battery pack is fully charged.

[0011] Therefore, in one embodiment of the present invention, it is preferred to provide a battery pack and a charging system that can suppress the situation in which the charging stop function is activated due to the increase in battery cell voltage caused by the increase in charging current, while also being able to shorten the charging time.

[0012] A storage battery pack according to one aspect of the present invention includes a storage battery cell, a storage unit, a target current calculation unit, and an information notification unit.

[0013] The storage battery cell is configured to be charged by a charging current from a charger. The storage unit is configured to store a maximum current variation. The maximum current variation is a maximum value of a variation of a charging current during charging control.

[0014] The target current calculation unit is configured to calculate a target current value, which is a control target value of the charging current supplied to the battery cell. The target current calculation unit is configured to calculate a value obtained by adding the maximum current change amount to the target current value at the time of the previous calculation as a new target current value. The information notification unit is configured to notify the charger of the charging condition information including the new target current value. The maximum current change amount is determined according to the characteristics of the battery pack.

[0015] Since the battery pack calculates a new target current value using the maximum current change amount determined according to the characteristics of the battery pack, the current increase amount in one current change when calculating the target current value can be used as a value corresponding to the characteristics of the battery pack. The information notification unit notifies the charger of the charging condition information including the target current value, so that the battery pack can notify the charger of the target current value of the charging current corresponding to the characteristics of the battery pack.

[0016] Thus, the battery pack can suppress a situation in which the current increase amount of the charging current in one current change (in other words, the maximum current change amount) becomes excessive when the battery pack is charged by the charger, and can set the change amount of the charging voltage accompanying the charging current change within a range corresponding to the characteristics of the battery pack.

[0017] According to this, since the battery pack can suppress the situation where the amount of change in the charging voltage becomes too large, it can suppress the situation where the charging stops prematurely or the battery cell is damaged. The so-called premature charging stops, for example, because the charging voltage of the battery cell increases abnormally before the charging is completed, resulting in the charging operation being stopped. The so-called battery cell damage refers to the situation where the battery cell is damaged, for example, due to the battery cell voltage being out of the allowable range.

[0018] Next, in the above-mentioned battery pack, the maximum current variation amount may be determined based on the characteristics of the battery cell. The characteristics of the battery cell may include the impedance of the battery cell.

[0019] The amount of change in the charging voltage accompanying the current change of the charging current varies, for example, according to the characteristics of the battery cell (such as the impedance of the battery cell). Thus, by using the maximum current change determined based on the impedance of the battery cell, the amount of change in the charging voltage can be set to a value suitable for the characteristics of the battery pack. Accordingly, since the battery pack limits the amount of change in the charging voltage according to the characteristics of the battery cell, it is possible to suppress the situation where the amount of change in the charging voltage becomes excessive.

[0020] Next, in the above-mentioned storage battery pack, the storage battery cell may be configured to include a plurality of cells connected in parallel. The characteristics of the storage battery cell may also include a parallel connection state of the plurality of cells.

[0021] In a battery cell having a plurality of cells connected in parallel, the amount of change in the charging voltage accompanying the current change of the charging current changes according to the parallel connection state of the plurality of cells (for example, the number of cells connected in parallel). Accordingly, the parallel connection state of the plurality of cells is included as a characteristic of the battery cell for determining the maximum current change, so that even when the battery cell has a plurality of cells connected in parallel, the amount of change in the charging voltage can be set to a value suitable for the characteristics of the battery pack.

[0022] Next, the battery pack may also include an action information acquisition unit. The action information acquisition unit is configured to acquire charging action information from a charger. The charging action information is information related to the charging action of the charger. The charging action information includes information about the charging current output by the charger to the battery pack. The target current calculation unit may replace the target current value of the previous calculation with the charging current of the charging action information to calculate a new target current value.

[0023] Since the battery pack can obtain the charging operation information from the charger, it can accurately grasp the charging current output by the charger to the battery pack. When calculating a new target current value, the battery pack can replace the target current value calculated last time and use the charging current of the charging operation information. Therefore, even if an error occurs between the target current value calculated last time and the charging current, the new target current value can be properly calculated.

[0024] According to this, the storage battery pack can suppress the new target current value calculated by the target current calculation unit from becoming an inappropriate value, and can suppress the amount of change in the charging voltage from becoming excessively large.

[0025] Next, the above-mentioned storage battery pack may also include a cell voltage comparison unit. The cell voltage comparison unit is configured to compare the cell voltage of the storage battery cell with the charging voltage target value to determine whether the cell voltage is less than the charging voltage target value. The charging voltage target value may be a target value of the cell voltage in the storage battery cell during charging. The target current calculation unit may calculate a new target current value by adding the maximum current change amount to the target current value during the previous calculation based on the cell voltage comparison unit determining that the cell voltage is less than the charging voltage target value.

[0026] Thus, the battery pack can maintain the cell voltage of the battery cell within the allowable range and calculate a new target current value in such a way that the charging current increases. Thus, the battery pack can increase the charging current within the allowable range and shorten the charging time from the start to the end of charging.

[0027] Next, in the battery pack, the target current calculation unit can calculate a new target current value by subtracting the maximum current change amount from the target current value calculated last time, based on the cell voltage comparison unit determining that the cell voltage is above the target charging voltage value.

[0028] According to this, when the cell voltage is above the charging voltage target value, the battery pack reduces the target current value, thereby preventing the cell voltage of the battery cell from deviating from the allowable range, and calculating a new target current value. According to this, the battery pack can prevent the charging from being stopped due to the cell voltage deviating from the allowable range, and can continue the normal charging operation.

[0029] Next, the battery pack may include a charging current comparison unit. The charging current comparison unit may be configured to compare the provisional current value with the current reference value and determine whether the provisional current value is below the current reference value. The provisional current value is a value obtained by adding the maximum current change amount to the target current value in the previous calculation. The current reference value may be an upper limit value of the charging current allowed in the battery cell during charging.

[0030] The target current calculation unit may calculate a new target current value by adding the maximum current change amount to the target current value calculated last time, based on the charging current comparison unit determining that the provisional current value is below the current reference value. The target current calculation unit may set the current reference value as the new target current value, based on the charging current comparison unit determining that the provisional current value is greater than the current reference value.

[0031] Thus, the battery pack can maintain the charging current of the battery cell within the allowable range, and can also calculate a new target current value in a manner that increases the charging current. Thus, the battery pack can increase the charging current within the allowable range and shorten the charging time from the start to the end of charging.

[0032] In addition, the battery pack can suppress the situation where the charging current of the battery cell deviates from the allowable range and can also calculate a new target current value. Accordingly, the battery pack can suppress the situation where charging is stopped due to the charging current deviating from the allowable range and can continue the normal charging operation.

[0033] A charging system according to another aspect of the present invention may include the above-mentioned battery pack and charger.

[0034] The charger may include: a current output unit, a condition information acquisition unit, and an output current setting unit. The current output unit may be configured to output a charging current. The condition information acquisition unit may be configured to acquire charging condition information from a storage battery pack. The output current setting unit may be configured to set the charging current output from the current output unit. The output current setting unit may be configured to set the charging current based on a new target current value, wherein the new target current value is a current value based on the charging condition information.

[0035] In this charging system, the charging condition information is notified from the storage battery pack to the charger, and the charger outputs a charging current set based on a new target current value, wherein the new target current value is a current value based on the charging condition information. Since this charging system includes the above-mentioned storage battery pack, it is possible to suppress the situation where the amount of change in the charging voltage becomes excessive, similarly to the above-mentioned storage battery pack, and thus it is possible to suppress the situation where the charging is stopped prematurely or the storage battery cell is damaged.

[0036] In the above charging system, the charger may include an output current comparison unit. The output current comparison unit may be configured to compare the new target current value with the output current upper limit value to determine whether the new target current value is below the output current upper limit value. The output current upper limit value may be an upper limit value of the charging current determined according to the temperature of the charger.

[0037] The output current setting unit may set the new target current value as the charging current based on the output current comparison unit determining that the new target current value is below the output current upper limit value. The output current setting unit may set the output current upper limit value as the charging current based on the output current comparison unit determining that the new target current value is greater than the output current upper limit value.

[0038] According to this, the charging system can suppress damage to the charger due to excessive temperature rise when the charger charges the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a block diagram showing an overview of a battery pack and a charger.

[0040] Figure 2 This is a flowchart showing the processing contents of the charging control process executed by the device-side MPU of the charger.

[0041] Figure 3 This is a flowchart showing the processing contents of the charging condition setting process executed by the MPU of the storage battery pack.

[0042] Figure 4 1 is a timing chart showing the waveforms of the battery cell voltage Vnow and the present output current value Inow in the present embodiment.

[0043] Figure 5 1 is a timing chart showing the waveforms of the battery cell voltage Vnow and the present output current value Inow in Comparative Example 1.

[0044] Figure 6 1 is a timing chart showing waveforms of the battery cell voltage Vnow, the present output current value Inow, and the charge capacity QV in the present embodiment.

[0045] Figure 7 1 is a timing chart showing the waveforms of the battery cell voltage Vnow, the present output current value Inow, and the charge capacity QV in Comparative Example 2.

[0046] Explanation of symbols

[0047] 1…charging system; 60…battery cell; 67…shunt resistor; 100…battery pack; 200…charging control unit (CS circuit); 300…detection unit (DT circuit); 400…communication unit (half-duplex I / F circuit); 500…discharge control unit (DS circuit); 600…charger; 611…device-side MPU; 613…device-side power supply circuit; 619…device-side communication unit; 620…MPU; 621…shunt resistor; 625…temperature detection unit; 627…storage unit. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments to which the present invention is applied will be described using the drawings.

[0049] In addition, the present invention is not limited to the following embodiments at all, and it is apparent that various forms can be adopted as long as they fall within the technical scope of the present invention.

[0050] [1. First embodiment]

[0051] [1-1. Overall composition]

[0052] Reference Figure 1 , the structure of the battery pack 100 according to the present embodiment will be described.

[0053] The charging system 1 includes a battery pack 100 and a charger 600 .

[0054] The battery pack 100 is configured to be connected to an external device to supply power to the external device, and is also configured to be connected to an external device to receive power from the external device. The external device includes a charger 600, an electric working machine, a lamp, etc. The charger 600 supplies power to the battery pack 100. The electric working machine and the lamp receive power and operate. The electric working machine includes electric tools such as a hammer drill, an electric saw, and a grinder, as well as a lawn mower, a hedge trimmer, a hair clipper, etc.

[0055] like Figure 1 As shown, the battery pack 100 is connected to a charger 600 and is configured to receive power supply from the charger 600 .

[0056] The battery pack 100 includes a battery cell 60, an analog front end 610 (hereinafter also referred to as AFE610), a micro processing unit 620 (hereinafter also referred to as MPU620), a power supply circuit 116, and a self-control protector 118 (hereinafter also referred to as SCP118).

[0057] In addition, the battery pack 100 includes: a positive terminal 11, a negative terminal 12, a CS terminal 13, a DT terminal 14, a TR terminal 15, a DS terminal 16, a charging control unit 200 (hereinafter also referred to as a CS circuit 200), a detection unit 300 (hereinafter also referred to as a DT circuit 300), a communication unit 400 (hereinafter also referred to as a UART half-duplex I / F circuit 400), a discharge control unit 500 (hereinafter also referred to as a DS circuit 500), and a storage unit 627.

[0058] The battery cell 60 is configured to include a plurality of cells. The plurality of cells are connected in parallel. The battery cell 60 is a secondary battery capable of being charged and discharged, such as a lithium-ion battery. The rated voltage of the battery cell 60 of the present embodiment is, for example, 18V. In addition, the rated voltage of the battery cell 60 is not limited to 18V, and may be 36V or 72V, etc. The battery cell 60 is configured to be charged by a charging current from a charger 600 connected to the battery pack 100.

[0059] MPU620 includes a microcomputer with CPU, ROM, RAM and I / O, etc., and performs various controls including charge and discharge control of the battery cell 60. In addition, MPU620 has multiple interrupt ports PI (not shown) for inputting various signals. MPU620 uses the detection unit 300 to detect the connection status with the charger 600. When the specified conditions are met, it switches from the normal operation mode (control operation state) to the sleep mode (low power operation state) in which part of the operation is stopped to suppress power consumption. In addition, in the sleep mode, if a signal is input to any interrupt port PI, MPU620 wakes up and switches to the normal operation mode. For example, MPU620 detects the connection status with the charger 600 using the detection unit 300, and wakes up if the connection detection information Sa1 is input via the interrupt port PI. In addition, MPU620 detects the removal of the charger 600, and switches to the sleep mode when the specified conditions are met.

[0060] That is, the MPU 620 is configured to be switchable to any one of a plurality of operation modes (operation states) including a normal operation mode (control operation state) and a sleep mode (low power operation state). The control operation state is an operation state in which the charging and discharging of the battery cell 60 are controlled. The low power operation state is an operation state in which the charging and discharging of the battery cell 60 are not controlled, and the power consumption is less than that of the control operation state.

[0061] AFE610 is an analog circuit that detects the cell voltage of each of the multiple cells included in the battery cell 60 according to the instruction from MPU620, and detects the cell temperature of at least one of the multiple cells by means of a thermistor (not shown) equipped in the battery cell 60. In addition, AFE610 performs a cell balancing process to equalize the remaining power of each of the multiple cells. In addition, AFE610 detects the substrate temperature by means of a thermistor (not shown) equipped in the circuit substrate. In addition, AFE610 detects the charging current flowing into the battery cell 60 and the discharging current flowing out of the battery cell 60 by means of the shunt resistor 67. In addition, AFE610 converts the detected cell voltage, cell temperature, substrate temperature, and charge and discharge current detection values ​​into digital signals, and outputs the converted digital signals to MPU620.

[0062] Furthermore, the AFE 610 determines whether to permit or prohibit charging of the battery cell 60 based on the detected state of the battery 60 , generates a charging permission signal or a charging prohibition signal, and outputs the signal to the charging control unit 200 .

[0063] The power supply circuit 116 includes a regulator. When the battery pack 100 (more specifically, the MPU 620) is turned off, the regulator receives power from the auxiliary power supply 623 of the charger 600 via the DS terminal 16 to generate a power supply voltage VDD for driving the internal circuit. The charger 600 includes a device-side DS terminal 66 connected to the DS terminal 16. The device-side DS terminal 66 is connected to the auxiliary power supply 623.

[0064] The battery pack 100 is shut down when it is in an over-discharge state. When the MPU 620 receives the supply of the power supply voltage VDD generated by the power supply circuit 116, it starts from the shutdown state, and if the battery cell 60 is in a chargeable state, it outputs a charge permission signal to the charger 600. When the battery voltage reaches a predetermined voltage, the power from the battery cell 60 is supplied to the power supply circuit 116. The power supply circuit 116 receives power from the battery cell 60 to generate the power supply voltage VDD.

[0065] The SCP 118 is provided on the positive electrode side connection line connecting the positive electrode side of the storage battery cell 60 and the positive electrode terminal 11. The SCP 118 includes a fuse and a circuit that blows the fuse according to a command from the MPU 620. When the fuse of the SCP 118 is blown, the positive electrode side connection line can be disconnected, and the storage battery cell 60 is in a state where it cannot be charged or discharged via the positive electrode terminal 11. That is, the storage battery cell 60 is in a state where it cannot be reused.

[0066] In the case where charging is not stopped even when a charging prohibition signal is output from the battery pack 100 to the charger 600, and in the case where discharging is not stopped even when a discharging prohibition signal is output from the battery pack 100 to an external device, as a last resort, the MPU 620 issues a command to the SCP 118 to blow the fuse in order to ensure safety. That is, the SCP 118 is a circuit for doubly ensuring safety for the overcharge state and overdischarge state of the battery cell 60. The SCP 118 can periodically diagnose whether the circuit that blows the fuse is operating normally, and output the diagnosis result to the MPU 620. In the case where the SCP 118 does not have a self-diagnosis function, the MPU 620 can perform SCP diagnosis processing to determine whether the SCP 118 is operating normally.

[0067] The MPU 620 determines the state of the battery cell 60 based on the various signals input. Furthermore, the MPU 620 determines whether to allow charging of the battery cell 60 or prohibit charging of the battery cell 60 based on the determined state of the battery cell 60, and generates a charge permission signal or a charge prohibition signal. The MPU 620 outputs the charge permission signal or the charge prohibition signal to the charge control unit 200 via the AFE 610. Furthermore, the MPU 620 determines whether to allow discharge from the battery cell 60 or prohibit discharge from the battery cell 60 based on the determined state of the battery cell 60, and generates a discharge permission signal or a discharge prohibition signal, and outputs it to the discharge control unit 500. Furthermore, in order to improve the responsiveness to the external device (specifically, the electric working machine), the MPU 620 may continuously generate a discharge permission signal in the sleep mode and output it to the discharge control unit 500.

[0068] When the battery pack 100 is connected to an external device (not shown) or a charger 600, the positive terminal 11 and the negative terminal 12 are connected to the device-side positive terminal and the device-side negative terminal of the external device, or the device-side positive terminal 61 and the device-side negative terminal 62 of the charger 600. Thus, power can be supplied from the battery pack 100 to the external device or from the charger 600 to the battery pack 100.

[0069] The CS terminal 13 is connected to the charging control unit 200 (CS circuit 200), and when the storage battery pack 100 is connected to the charger 600, the CS terminal 13 is a terminal for outputting a charging permission signal or a charging prohibition signal to the charger 600. When the charging permission signal is input from the AFE 610, the charging control unit 200 outputs the charging permission signal via the CS terminal 13. In addition, when the charging prohibition signal is input from the AFE 610, the charging control unit 200 outputs the charging prohibition signal via the CS terminal 13.

[0070] The storage unit 627 is configured to store the maximum current change ΔIbat used in the target current calculation process described later. The storage unit 627 is configured by a storage device (memory, etc.) that can read various stored information (for example, the maximum current change ΔIbat, etc.) by the MPU 620. The maximum current change ΔIbat is the maximum value of the change in the charging current during the charging control.

[0071] The maximum current variation ΔIbat is set according to the characteristics of the battery pack 100. In the present embodiment, the maximum current variation ΔIbat is set based on the characteristics of the battery cell 60. The characteristics of the battery cell 60 include: the impedance Z of the battery cell 60, and the parallel connection state of the plurality of cells (for example, the number of cells connected in parallel). Therefore, when the types of the battery pack 100 are different, the maximum current variation ΔIbat that is different for each battery pack 100 is stored in the storage unit 627. Specifically, the maximum current variation ΔIbat is set in such a way that the voltage variation ΔViz calculated by multiplying the impedance Z by the maximum current variation ΔIbat is less than the difference ΔVa (=Vcut-CV) between the charge end voltage value Vcut described later and the charge voltage target value CV described later.

[0072] The charger 600 includes a device-side CS terminal 63 connected to the CS terminal 13. The charger 600 includes an interlock protection circuit 617 connected to the device-side CS terminal 63. The charger 600 includes a device-side power supply circuit 613 as a power supply for supplying DC power. The interlock protection circuit 617 permits the power supply operation by the device-side power supply circuit 613 when receiving a charge permission signal from the battery pack 100, and prohibits the power supply operation by the device-side power supply circuit 613 when receiving a charge prohibition signal from the battery pack 100. The device-side power supply circuit 613 is configured to convert AC power from a commercial power supply (for example, AC 100V) into DC power by an AC / DC converter or the like, and supply the DC power.

[0073] When the battery pack 100 is connected to the charger 600, the DT terminal 14 is connected to the device-side communication terminal 64 of the charger 600. The device-side communication terminal 64 is connected to the battery detection unit 630. The potential VDT of the DT terminal 14 changes depending on whether the charger 600 is disconnected or connected. In addition, the potential VDT of the device-side communication terminal 64 and the DT terminal 14 changes depending on whether the battery pack 100 is in a shutdown state or a non-shutdown state.

[0074] The battery detection unit 630 determines whether the potential VDT of the device-side communication terminal 64 and the DT terminal 14 indicates the shutdown state of the battery pack 100 or the non-shutdown state. The battery detection unit 630 detects shutdown information indicating whether the battery pack 100 is in the shutdown state based on the determination result. When the battery detection unit 630 detects that the battery pack 100 is in the non-shutdown state, it turns on the discharge switch 615 provided on the positive electrode side connection line. The positive electrode side connection line is a power line provided between the device-side positive terminal 61 and the device-side power supply circuit 613.

[0075] As a result, the charger 600 supplies power to the battery pack 100, and the battery 60 is charged. When the battery detector 630 detects that the battery pack 100 is in the shutdown state, it turns off the discharge switch 615.

[0076] The DT terminal 14 is connected to the detection unit 300 of the battery pack 100. The detection unit 300 detects the potential VDT of the DT terminal 14, and determines whether the charger 600 is in a potential indicating that it is not connected to the battery pack 100 based on the detected potential VDT, thereby detecting the unconnected state or the connected state. The detection unit 300 outputs the detection result to the MPU 620 via the interrupt port PI (not shown). In addition, the detection unit 300 can output the detection result to the AFE 610. In addition, the detection unit 300 can output the detection result to the MPU 620 and the AFE 610 respectively.

[0077] Based on the input detection result, MPU 620 acquires device information including disconnection information, disconnection information, and connection information. Device information (disconnection information, disconnection information, and connection information) is information sent from charger 600 to battery pack 100 and received by battery pack 100 .

[0078] The disconnected information is information indicating that the charger 600 is not connected to the battery pack 100. The disconnected information is information indicating that the charger 600 is connected to the battery pack 100 and the discharge switch 615 is turned off. The connected information is information indicating that the charger 600 is connected to the battery pack 100 and the discharge switch 615 is turned on.

[0079] The TR terminal 15 is a serial communication terminal connected to the communication unit 400. The communication unit 400 includes a half-duplex Universal Asynchronous Receiver / Transmitter (UART) circuit.

[0080] The charger 600 includes a device-side TR terminal 65 connected to the TR terminal 15, and a device-side communication unit 619 connected to the device-side TR terminal 65. The device-side communication unit 619 includes a half-duplex Universal Asynchronous Receiver / Transmitter (UART) circuit.

[0081] The charger 600 includes a device-side MPU 611. The device-side MPU 611 includes a microcomputer including a CPU, ROM, RAM, and I / O, and performs various controls including charging control of the charger 600. The device-side MPU 611 detects the discharge current flowing from the device-side power supply circuit 613 by means of a shunt resistor 621. When the detected discharge current has an abnormal value, the device-side MPU 611 switches the discharge switch 615 to an off state, for example, thereby stopping the charging of the storage battery 60 with the discharge current of the abnormal value.

[0082] After charging of the battery pack 100 is completed, the device-side MPU 611 switches from the normal operation mode (controlled operation state) to the sleep mode (low-power operation state) in which a part of the operation is stopped to suppress power consumption when the prescribed conditions are met. Before switching from the normal operation mode to the sleep mode, the device-side MPU 611 transmits a sleep transition signal Sa2 to the MPU 620 via the device-side communication unit 619. The sleep transition signal Sa2 is a parameter signal indicating that the device-side MPU 611 of the charger 600 switches to the sleep mode.

[0083] When the device-side MPU 611 is in sleep mode, if a signal is input to any interrupt port PI, it wakes up and switches to normal operation mode. For example, the device-side MPU 611 detects the connection status with the battery pack 100, and wakes up if the connection detection information Sb1 is input via the interrupt port PI. In addition, the device-side MPU 611 detects the removal of the battery pack 100, and switches to sleep mode when the specified conditions are met.

[0084] The MPU 620 and the device-side MPU 611 perform serial communication via the communication unit 400, the TR terminal 15, the device-side TR terminal 65, and the device-side communication unit 619. The MPU 620 and the device-side MPU 611 are configured to perform communication every predetermined communication cycle Tc (for example, Tc=8 [sec]) during the period when the communication connection is established. The MPU 620, the communication unit 400, and the TR terminal 15 function as a communication unit, wherein the communication unit is configured to perform bidirectional communication with the charger 600.

[0085] The DS terminal 16 is connected to the discharge control unit 500. When the battery pack 100 is connected to an external device (specifically, an electric working machine), the DS terminal 16 outputs a discharge permission signal or a discharge prohibition signal to the external device. The discharge control unit 500 outputs a discharge permission signal or a discharge prohibition signal via the DS terminal 16 based on the discharge permission signal or the discharge prohibition signal input from the MPU 620. In addition, when the battery pack 100 in the shutdown state is connected to the charger 600, the DS terminal 16 receives power from the auxiliary power supply 623 via the device-side DS terminal 66.

[0086] The charger 600 includes a temperature detection unit 625 configured to detect the temperature of the charger 600. The temperature detection unit 625 sends a detector temperature T1 indicating the detected temperature to the device-side MPU 611. The device-side MPU 611 stores the detector temperature T1 in a storage device such as a RAM. The temperature detection unit 625 may include, for example, a thermistor (not shown) provided adjacent to any one of the device-side power supply circuit 613, the FET 615, the shunt resistor 621, etc. in the charger 600.

[0087] [1-2. Charging Condition Setting Process and Charging Control Process]

[0088] Various processes performed by the charger 600 and the battery pack 100 during charging will be described. Figure 2 as well as Figure 3 The charging control process executed by the device-side MPU 611 of the charger 600 and the charging condition setting process executed by the MPU 620 of the battery pack 100 are respectively described with reference to the flowcharts of FIG.

[0089] The device-side MPU 611 detects the connection status with the battery pack 100, and when the connection detection information Sb1 is inputted via the interrupt port PI, it wakes up and starts the charging control process. The MPU 620 detects the connection status with the charger 600 using the detection unit 300, and when the connection detection information Sa1 is inputted via the interrupt port PI, it wakes up and starts the operation in the normal operation mode (control operation state), and starts the charging condition setting process.

[0090] In addition, the charging control process performed by the device-side MPU 611 and the charging condition setting process performed by the MPU 620 are started synchronously and then executed in parallel.

[0091] When the device-side MPU 611 starts the charging control process, it first performs the initial communication process in S110 (S represents a step. The same applies to the following). In addition, when the MPU 620 starts the charging condition setting process, it performs the initial communication process in S310. The initial communication process is a process for confirming that signals can be sent and received between the battery pack 100 and the charger 600 (in other words, between the MPU 620 and the device-side MPU 611).

[0092] When the initial communication process is completed normally, the device-side MPU 611 moves to S120 and sets 0 [A] as the current output current value Inow. The current output current value Inow is one of the internal variables used in the charging control process of the device-side MPU 611. The current output current value Inow is an internal variable for storing the current value of the discharge current output by the device-side power supply circuit 613. The discharge current output by the device-side power supply circuit 613 is also equivalent to the charging current for charging the storage battery pack 100.

[0093] In the subsequent S130 , the device-side MPU 611 transmits the present output current value Inow to the MPU 620 of the storage battery pack 100 . Specifically, the device-side MPU 611 transmits the numerical value set as the present output current value Inow to the MPU 620 .

[0094] On the other hand, when the initial communication processing is normally completed, MPU620 receives the current output current value Inow from the device-side MPU611 of the charger 600 in S320. At this time, MPU620 waits until the current output current value Inow is received. That is, MPU620 executing S320 is configured to obtain the current output current value Inow as one of the charging action information from the charger 600. The charging action information is information related to the charging action of the charger 600. The current output current value Inow is information about the charging current output by the charger 600 to the battery pack 100. In addition, in detail, MPU620 obtains the current output current value Inow from the device-side MPU611 with the help of the communication unit 400 and the device-side communication unit 619.

[0095] In the next S140, the device-side MPU 611 acquires the charger temperature T1 from the temperature detection unit 625. The device-side MPU 611 stores the detector temperature T1, which is one of the internal variables used in the charging control process, in a storage device such as a RAM.

[0096] In the subsequent S150, the device-side MPU611 determines the output current upper limit value Ic1 based on the detector temperature T1. The output current upper limit value Ic1 is: the upper limit value of the current allowed as the charging current output by the charger 600. The output current upper limit value Ic1 is: one of the internal variables used in the charging control process of the device-side MPU611. The device-side MPU611 uses a calculation formula or mapping information determined based on the correlation between the charger temperature T1 and the output current upper limit value Ic1 to calculate the output current upper limit value Ic1 corresponding to the charger temperature T1, and sets the calculation result as: the output current upper limit value Ic1 as the internal variable. The higher the charger temperature T1 of the charger 600, the smaller the output current upper limit value Ic1 will be set by the device-side MPU611.

[0097] On the other hand, MPU620 obtains the battery cell voltage Vnow and the battery temperature Tb in S330. MPU620 obtains the voltage of the battery cell 60 from AFE610 and stores it in RAM or the like as the battery cell voltage Vnow. MPU620 obtains the cell temperature of the battery cell 60 from AFE610 and stores it in RAM or the like as the battery temperature Tb.

[0098] In the next step S340 , the MPU 620 sets a current reference value Iset, a charging voltage target value CV, and a charging end current value Icut. These values ​​are internal variables used in the charging control process of the device-side MPU 611 .

[0099] The current reference value Iset is the upper limit value of the charging current allowed at the battery cell 60 during charging. The MPU 620 calculates the current reference value Iset corresponding to the battery temperature Tb acquired in S330 using a calculation formula determined based on the correlation between the current reference value Iset and the battery temperature Tb, or mapping information, and sets the calculation result as the current reference value Iset as an internal variable.

[0100] The charging voltage target value CV is a target value of the cell voltage in the battery cell 60 during charging. The MPU 620 calculates the charging voltage target value CV corresponding to the battery temperature Tb acquired in S330 using a calculation formula determined based on the correlation between the charging voltage target value CV and the battery temperature Tb, or mapping information, and sets the calculation result as the charging voltage target value CV as an internal variable.

[0101] The charge end current value Icut is a determination value for determining the charge end of the battery cell 60, and is a value equivalent to the charging current supplied from the charger 600 when the battery cell 60 is in the charge end state. The MPU 620 calculates the charge end current value Icut corresponding to the battery temperature Tb acquired in S330 using a calculation formula determined based on the correlation between the charge end current value Icut and the battery temperature Tb, or mapping information, and sets the calculation result as the charge end current value Icut as an internal variable.

[0102] In the subsequent S350, the MPU 620 determines whether the battery cell voltage Vnow is greater than the charging voltage target value CV. If the determination is positive, the process moves to S390, and if the determination is negative, the process moves to S360. In other words, the MPU 620 executing S350 compares the battery cell voltage Vnow, which is the cell voltage of the battery cell 60, with the charging voltage target value CV to determine whether the battery cell voltage Vnow is less than the charging voltage target value CV.

[0103] When MPU620 makes a negative judgment in S350 and transfers to S360, it determines whether the total value Ite (= Inow + ΔIbat. Hereinafter, it is also referred to as the provisional current value Ite) of the current output current value Inow and the maximum current change amount ΔIbat is greater than the current reference value Iset. When a positive judgment is made, it transfers to S380, and when a negative judgment is made, it transfers to S370. At this time, MPU620 uses the maximum current change amount ΔIbat read from the storage unit 627 to calculate the provisional current value Ite. In other words, MPU620 executing S360 compares the provisional current value Ite with the current reference value Iset to determine whether the provisional current value Ite is below the current reference value Iset.

[0104] When the MPU620 makes a negative judgment in S360 and transfers to S370, the total value of the current output current value Inow and the maximum current change ΔIbat (in other words, the provisional current value Ite) is set as the target current value Inext. In addition, the target current value Inext is: the control target value of the charging current supplied to the battery cell 60. That is, the MPU620 executing S370 calculates the value obtained by adding the maximum current change ΔIbat to the current output current value Inow as the new target current value Inext. In addition, in S370, the target current value Inext can also be calculated by replacing the current output current value Inow and using the target current value Inext at the time of the previous calculation.

[0105] When the MPU 620 makes an affirmative determination in S360 and moves to S380 , the MPU 620 sets the current reference value Iset as the target current value Inext.

[0106] When the MPU 620 makes an affirmative determination in S350 and moves to S390, it determines whether the battery cell voltage Vnow is greater than the charge end voltage value Vcut, and moves to S430 when the determination is affirmative, and moves to S400 when the determination is negative. The charge end voltage value Vcut is a determination value for determining the charge end of the battery cell 60, and is a value equivalent to the voltage of the battery cell 60 when the battery cell 60 is in the charge end state.

[0107] When the MPU620 makes a negative determination in S390 and transfers to S400, the value obtained by subtracting the maximum current change amount ΔIbat from the current output current value Inow is set as the target current value Inext. In this embodiment, although the maximum current change amount ΔIbat is used for subtraction, the maximum current change amount ΔIbat can also be replaced by using other numerical values ​​for subtraction (for example, the current reduction reference amount ΔIbat2) to perform subtraction, thereby setting the target current value Inext. That is, in the case of increasing the target current value Inext and in the case of reducing the target current value Inext, different numerical values ​​can also be used to set the target current value Inext.

[0108] In the next S410, the MPU 620 determines whether the target current value Inext is less than the charge end current value Icut, and if it is determined to be positive, it moves to S430, and if it is determined to be negative, it moves to S420. The charge end current value Icut is a determination value for determining whether the charging of the battery cell 60 is completed.

[0109] In S420, the MPU 620 transmits the target current value Inext to the device-side MPU 611 of the charger 600. That is, the MPU 620 transmits the target current value Inext set in any of steps S370, S380, and S400 to the device-side MPU 611. The MPU 620 transmits the target current value Inext to the device-side MPU 611 via the communication unit 400 and the device-side communication unit 619. Thus, the target current value Inext is notified from the battery pack 100 to the charger 600.

[0110] Meanwhile, the device-side MPU 611 receives the target current value Inext from the MPU 620 in S160. At this time, the device-side MPU 611 waits until the target current value Inext is received. That is, the device-side MPU 611 executing S160 acquires the target current value Inext as one of the charging condition information from the storage battery pack 100.

[0111] In the subsequent S170, the device-side MPU 611 determines whether the target current value Inext is greater than the output current upper limit value Ic1. If the determination is positive, the process moves to S190, and if the determination is negative, the process moves to S180. That is, the device-side MPU 611 executing S170 determines whether the new target current value Inext is below the output current upper limit value Ic1.

[0112] When the device-side MPU 611 makes a negative determination in S170 and moves to S180, the target current value Inext is set as the output current Iout. When the device-side MPU 611 makes a positive determination in S170 and moves to S190, the output current upper limit value Ic1 is set as the output current Iout. The device-side MPU 611 controls the output current output by the device-side power supply circuit 613 based on the setting content of the output current Iout. That is, in the charger 600, the output current corresponding to the output current Iout is output from the device-side power supply circuit 613.

[0113] That is, the device-side MPU 611 executing S180 and S190 sets the charging current output from the device-side power supply circuit 613. In particular, the device-side MPU 611 executing S180 sets the charging current output from the device-side power supply circuit 613 based on the target current value Inext.

[0114] In the subsequent S200 , the device-side MPU 611 sets the output current Iout to the present output current value Inow.

[0115] After executing S200, the device-side MPU 611 shifts to S130 again. Thereafter, the device-side MPU 611 executes the processes from S130 to S200.

[0116] On the other hand, the MPU 620 determines that the charging of the battery cell 60 is completed in S430, and sends a charging completion signal Ss for notifying the completion of charging to the device-side MPU 611 of the charger 600. After executing S430, the MPU 620 terminates the charging condition setting process. In addition, when the device-side MPU 611 receives the charging completion signal Ss, it terminates the charging control process.

[0117] Thus, the battery pack 100 executes the charging condition setting process and the charger 600 executes the charging control process, whereby the battery pack 100 sends the target current value Inext to the charger 600 ( S420 ), and the charger 600 outputs the output current Iout set based on the target current value Inext to the battery pack 100 ( S180 ).

[0118] The battery pack 100 also sets the target current value Inext ( S370 , S400 ) using the maximum current change amount ΔIbat set according to the characteristics of the battery pack 100 . This allows the target current value Inext to be changed according to the characteristics of the battery pack 100 .

[0119] Furthermore, when the provisional current value Ite is larger than the current reference value Iset, the storage battery pack 100 sets the current reference value Iset as the target current value Inext. This can prevent the target current value Inext from becoming excessively large.

[0120] [1-3. Comparative Description of the Present Embodiment and Comparative Example 1 (Premature Stop of Charging)]

[0121] Here, the charging system 1 of the present embodiment can suppress premature stop of charging, and a comparison between the present embodiment and Comparative Example 1 will be described.

[0122] As described above, the charging system 1 of the present embodiment charges the battery pack using the maximum current variation ΔIbat stored in the battery pack 100. The charging system of Comparative Example 1 (not shown) charges the battery pack using the maximum current variation stored in the charger.

[0123] First, when the battery pack 100 and the charger 600 of the present embodiment execute the charging condition setting process and the charging control process, the battery cell voltage Vnow and the current output current value Inow become Figure 4 The waveform shown.

[0124] That is, in this embodiment, when charging starts at time 0 [sec], the current output current value Inow increases in steps by the maximum current change amount ΔIbat each time, and the battery cell voltage Vnow also increases in steps. Then, when the battery cell voltage Vnow exceeds the charging voltage target value CV (at time 40 [sec]), the current output current value Inow decreases in steps by the maximum current change amount ΔIbat (at time 44 [sec]).

[0125] At this time, when the battery cell voltage Vnow exceeds not only the charging voltage target value CV but also the charging end voltage value Vcut, it is still determined that charging is ended, and charging is stopped. However, in the present embodiment, the maximum current change amount ΔIbat stored in the battery pack 100 is set according to the characteristics of the battery pack 100. Therefore, even when the current output current value Inow increases in a step-like manner with the maximum current change amount ΔIbat, it is possible to suppress the situation where the battery cell voltage Vnow exceeds not only the charging voltage target value CV but also the charging end voltage value Vcut.

[0126] Thereafter, along with the decrease of the current output current value Inow, when the battery cell voltage Vnow is lower than the charging voltage target value CV, the current output current value Inow will increase in steps with the maximum current change amount ΔIbat (at time 52 [sec]). Thereafter, when the battery cell voltage Vnow exceeds the charging voltage target value CV, the current output current value Inow will decrease in steps with the maximum current change amount ΔIbat.

[0127] That is, after the battery cell voltage Vnow reaches the charging voltage target value CV, the current output current value Inow is controlled to increase or decrease by the maximum current change ΔIbat so that the battery cell voltage Vnow is close to the charging voltage target value CV.

[0128] After that, although the battery cell voltage Vnow is close to the charging voltage target value CV, the current output current value Inow gradually decreases (from time t52 to t132 [sec]) as the charging capacity of the battery cell 60 increases. Furthermore, when the current output current value Inow is lower than the charging end current value Icut, it is determined that charging is ended, and charging is terminated (time 132 [sec]).

[0129] Next, when the battery pack and the charger of Comparative Example 1 perform charging control, the battery cell voltage Vnow and the current output current value Inow become Figure 5 The waveform shown.

[0130] In addition, the charging control process executed by the charger of Comparative Example 1 is configured as follows: Figure 2 The charging control process of the present embodiment shown does not include a step of receiving the target current value Inext from the battery pack 100, and the output current Iout is set by using the maximum current change amount ΔI2 stored in the charger instead of the target current value Inext. The maximum current change amount ΔI2 of Comparative Example 1 is set to a value larger than the maximum current change amount ΔIbat of the present embodiment.

[0131] In Comparative Example 1, when charging starts at time 0 [sec], the current output current value Inow increases stepwise by the maximum current change amount ΔI2 stored in the charger, and the battery cell voltage Vnow also increases stepwise. At this time, since the maximum current change amount ΔI2 is set to a value larger than the maximum current change amount ΔIbat, the voltage increase amount in Comparative Example 1 is larger than the voltage increase amount in this embodiment. As a result, the battery cell voltage Vnow not only exceeds the charging voltage target value CV, but also exceeds the charging end voltage value Vcut (at time t24 [sec]) by updating the current output current value Inow once based on the maximum current change amount ΔI2.

[0132] Thus, when the battery cell voltage Vnow exceeds the charging end voltage value Vcut, it is determined that charging is ended, and thus charging is stopped (refer to S390, S430). That is, in Comparative Example 1, the following premature charging stop occurs, that is, the premature charging stop is: regardless of whether the battery cell is not fully charged, it is wrongly determined that charging is ended, resulting in charging being stopped.

[0133] This is an example of what occurs when the maximum current variation ΔI2 stored in the charger is not suitable for the characteristics of the battery pack.

[0134] As described above, in this embodiment, compared with Comparative Example 1, it is possible to suppress the occurrence of premature stop of charging, and thus the storage battery pack 100 can be fully charged.

[0135] [1-4. Comparative Description of the Present Embodiment and Comparative Example 2 (Time Required Until Charging is Completed)]

[0136] Here, the present embodiment is compared with Comparative Example 2 to explain that the charging system 1 of the present embodiment can shorten the time required until the charging is completed.

[0137] As described above, the charging system 1 of this embodiment charges the battery pack using the maximum current variation ΔIbat stored in the battery pack 100. The charging system of Comparative Example 2 (not shown) is configured to charge the battery pack using the maximum current variation stored in the charger.

[0138] First, when the battery pack 100 and the charger 600 of the present embodiment execute the charging condition setting process and the charging control process, the battery cell voltage Vnow, the current output current value Inow, and the charging capacity QV become Figure 6 The charging capacity QV represents the charging capacity [Ah] of the battery cell 60 .

[0139] That is, in this embodiment, when charging starts at time 0 [sec], the current output current value Inow increases by the maximum current change amount ΔIbat each time, and the battery cell voltage Vnow increases accordingly, and the charging capacity QV increases. Then, the time required for the current output current value Inow to reach the current reference value Iset is about 44 [sec]. Thereafter, the current output current value Inow and the current reference value Iset are controlled to continue charging in a state where the current output current value Inow and the current reference value Iset are almost the same value, thereby further increasing the charging capacity QV.

[0140] Next, when the battery pack and the charger of Comparative Example 2 perform charging control, the battery cell voltage Vnow, the current output current value Inow, and the charging capacity QV become Figure 7 The waveform shown.

[0141] In addition, the charging control process executed by the charger of Comparative Example 2 is configured as follows: Figure 2 The charging control process of the present embodiment shown does not include a step of receiving the target current value Inext from the battery pack 100, and the output current Iout is set using the maximum current change amount ΔI2 stored in the charger instead of the target current value Inext. The maximum current change amount ΔI2 of Comparative Example 2 is set to a value smaller than the maximum current change amount ΔIbat of the present embodiment.

[0142] In Comparative Example 2, when charging starts at time 0 [sec], the current output current value Inow increases by the maximum current change amount ΔIbat each time, and the battery cell voltage Vnow also increases with this, and the charging capacity QV increases. However, in Comparative Example 2, compared with the present embodiment, since the maximum current change amount ΔIbat is smaller, the rising speed of the current output current value Inow is smaller, and the time required for the current output current value Inow to reach the current reference value Iset is about 188 [sec].

[0143] That is, in this embodiment, compared with Comparative Example 2, the time required for the current output current value Inow to reach the current reference value Iset is shorter, and accordingly, the rising speed of the charging capacity QV is also higher, so the time required to complete charging of the battery pack 100 can be shortened.

[0144] [1-5. Effect]

[0145] As described above, in the charging system 1, the battery pack 100 uses the maximum current change amount ΔIbat determined according to the characteristics of the battery cell 60 to calculate the new target current value Inext. As a result, the battery pack 100 can set the current increase amount in one current change when calculating the target current value Inext to a value corresponding to the characteristics of the battery cell 60. The target current value Inext is notified to the device-side MPU 611 of the charger 600 by the MPU 620, and the battery pack 100 can notify the charger 600 of the target current value Inext of the charging current corresponding to the characteristics of the battery cell 60.

[0146] Thus, when the battery pack 100 is charged using the charger 600, it is possible to suppress the current increase of the charging current in one current change (in other words, the maximum current change ΔIbat) from becoming too large, thereby being able to set the change in the charging voltage accompanying the change in the charging current within a range corresponding to the characteristics of the battery pack 100 (specifically, the battery cell 60).

[0147] According to this, the charging system 1 and the battery pack 100 can prevent the amount of change in the charging voltage from becoming too large, and thus can prevent the charging from being stopped prematurely or the battery cell 60 from being damaged. Figure 5 As shown in the example, the charging operation is stopped due to an abnormal increase in charging voltage before the charging of the battery cell is completed. The so-called damage of the battery cell 60 refers to, for example, the damage of the battery cell 60 due to the battery cell voltage being out of the allowable range.

[0148] Next, the maximum current variation ΔIbat is determined based on the characteristics of the battery cell 60 among the characteristics of the battery pack 100. The characteristics of the battery cell 60 include the impedance Z of the battery cell 60 and the parallel connection state of a plurality of cells (eg, the number of cells connected in parallel).

[0149] The amount of change in the charging voltage accompanying the current change of the charging current varies, for example, according to the characteristics of the battery cell 60 (impedance Z, the number of cells connected in parallel, etc.). Therefore, by using the maximum current change ΔIbat of the present embodiment, the amount of change in the charging voltage can be set to a value suitable for the characteristics of the battery cell 60 and further suitable for the characteristics of the battery pack 100. Accordingly, the charging system 1 and the battery pack 100 can set the amount of change in the charging voltage according to the characteristics of the battery cell 60, thereby preventing the amount of change in the charging voltage from becoming excessive.

[0150] Next, the battery pack 100 is configured to obtain the present output current value Inow, which is one of the charging operation information of the charger 600, from the charger 600. Based on the battery pack 100, the MPU 620 uses the present output current value Inow to calculate a new target current value Inext (see S370).

[0151] Since the storage battery pack 100 obtains the current output current value Inow as one of the charging operation information from the charger 600, it is possible to accurately grasp the charging current outputted by the charger 600 to the storage battery pack 100. Furthermore, since the storage battery pack 100 can use the current output current value Inow instead of the target current value Inext calculated last time when calculating a new target current value Inext, even if an error occurs between the target current value Inext calculated last time and the actual charging current, the new target current value Inext can be calculated appropriately.

[0152] Thus, the battery pack 100 can prevent the new target current value Inext calculated by the MPU 620 executing S370 from becoming an inappropriate value, and can prevent the amount of change in the charging voltage from becoming excessively large.

[0153] Next, in the battery pack 100, the MPU 620 executing the charging condition setting process determines that the battery voltage Vout is lower than the charging voltage target value CV (negative determination at S350), and adds the maximum current change ΔIbat to the current output current value Inow to calculate a new target current value Inext (S370).

[0154] Thus, the battery pack 100 can maintain the cell voltage of the battery cell 60 within the allowable range and calculate a new target current value Inext so as to increase the charging current. Thus, the battery pack 100 can increase the charging current within the allowable range, thereby shortening the charging time from the start to the end of charging.

[0155] In addition, in this embodiment, although Figure 3 As shown in the flowchart of , it is explained that after making a negative determination in S350, the process is transferred to S370 via S360, but it is not limited to such a form. For example, it can also be configured as follows: S360 is omitted and the process is directly transferred to S370. In addition, S380 can also be omitted when S360 is omitted.

[0156] Next, in the battery pack 100, the MPU 620 executing the charging condition setting process determines that the battery voltage Vout is above the charging voltage target value CV (affirmative determination at S350), and based on this determination, the maximum current change ΔIbat is subtracted from the current output current value Inow to calculate a new target current value Inext (S400).

[0157] According to this, when the battery voltage Vout is above the charging voltage target value CV, the battery pack 100 reduces the target current value Inext, thereby suppressing the cell voltage of the battery cell 60 from deviating from the allowable range, and calculating a new target current value Inext. According to this, by using the battery pack 100, it is possible to suppress the cell voltage from deviating from the allowable range and causing the charging to stop, while continuing the normal charging operation.

[0158] Next, in the storage battery pack 100, the MPU 620 that performs the charging condition setting process determines that the provisional current value Ite is below the current reference value Iset (negative determination in S360), and the maximum current change amount ΔIbat is added to the current output current value Inow to calculate a new target current value Inext (S370). In addition, the MPU 620 that performs the charging condition setting process determines that the provisional current value Ite is greater than the current reference value Iset (positive determination in S360), and the current reference value Iset is set as the new target current value Inext (S380).

[0159] Thus, the battery pack 100 can maintain the charging current of the battery cell 60 within the allowable range and can also calculate a new target current value Inext in such a way as to increase the charging current. Thus, the battery pack 100 can increase the charging current within the allowable range, thereby shortening the charging time from the start to the end of charging.

[0160] In addition, the battery pack 100 can suppress the charging current of the battery cell 60 from deviating from the allowable range and can also calculate a new target current value Inext. Therefore, by using the battery pack 100, it is possible to suppress the situation where charging is stopped due to the charging current deviating from the allowable range and continue the normal charging operation.

[0161] Next, in the charging system 1, the target current value Inext as the charging condition information is notified from the storage battery pack 100 to the charger 600, and the charger 600 outputs the charging current set based on the target current value Inext. According to this, since the charging system 1 includes the storage battery pack 100, it is possible to suppress the situation where the amount of change in the charging voltage becomes too large, thereby suppressing the situation where the charging is stopped prematurely or the battery cell is damaged.

[0162] Next, in the charger 600 of the charging system 1, the device-side MPU 611 that performs the charging control process sets the target current value Inext as the output current Iout (S180) based on the target current value Inext being less than the output current upper limit value Ic1 (negative determination in S170). In addition, the device-side MPU 611 that performs the charging control process sets the output current upper limit value Ic1 as the output current Iout (S190) based on the target current value Inext being greater than the output current upper limit value Ic1 (positive determination in S170).

[0163] According to this, the charging system 1 can suppress damage to the charger 600 due to an excessive temperature rise when the charger 600 charges the battery pack 100 .

[0164] [1-6. Correspondence between technical terms]

[0165] Here, the correspondence between technical terms is explained.

[0166] The MPU 620 executing S370, S380, and S400 is equivalent to an example of a target current calculation unit, the MPU 620 executing S420 and the communication unit 400 are equivalent to an example of an information notification unit, and the MPU 620 executing S330 and the communication unit 400 are equivalent to an example of an action information acquisition unit. The MPU 620 executing S350 is equivalent to an example of a single cell voltage comparison unit, and the MPU 620 executing S360 is equivalent to an example of a charging current comparison unit.

[0167] The device side power supply circuit 613 is equivalent to an example of a current output unit, the device side MPU611 executing S160 is equivalent to an example of a condition information acquisition unit, the device side MPU611 executing S180 or S190 is equivalent to an example of an output current setting unit, and the device side MPU611 executing S170 is equivalent to an example of an output current comparison unit.

[0168] [2. How he implemented it]

[0169] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be implemented in various forms within the scope not departing from the gist of the present invention.

[0170] (2a) In the above embodiment, although the specific current value of the maximum current change amount ΔIbat is not clearly described, the maximum current change amount ΔIbat can be set to an arbitrary value determined based on the characteristics of the battery pack (for example, the impedance of the battery cell, the parallel connection state of multiple cells (the number of parallel cells), etc.). In addition, the change amount of the charging voltage accompanying the current change of the charging current can be measured using an actual battery pack, and the maximum current change amount ΔIbat can be set based on the measurement result.

[0171] (2b) In the above embodiment, although the battery pack 100 obtains the current output current value Inow from the charger 600 (S320), the battery pack is not limited to this configuration. For example, in the charging condition setting process executed by the MPU of the battery pack, the current output current value Inow may be replaced with the previous target current value Inext to calculate a new target current value Inext.

[0172] (2c) In the above embodiment, a scheme in which serial communication is adopted as the communication method between the battery pack (communication unit 400) and the charger is described, however, the communication method is not limited to serial communication, and other communication methods such as parallel communication and multiple communication may be adopted. In addition, in the above embodiment, a scheme in which bidirectional communication is adopted as the communication method between the battery pack (communication unit 400) and the charger is described, however, unidirectional communication may be adopted. In this case, a plurality of unidirectional communication paths may be provided.

[0173] In addition, the functions of one constituent element in the above-mentioned embodiment may be distributed to a plurality of constituent elements, or the functions of a plurality of constituent elements may be concentrated in one constituent element. In addition, at least a portion of the configuration of the above-mentioned embodiment may be replaced with a known configuration having the same function. In addition, a portion of the configuration of the above-mentioned embodiment may be omitted. In addition, at least a portion of the configuration of the above-mentioned embodiment may be added to the configuration of other above-mentioned embodiments, or at least a portion of the configuration of the above-mentioned embodiment may be replaced with the configuration of other above-mentioned embodiments. In addition, all schemes included in the technical idea determined only by the technical terms recorded in the claims are embodiments of the present invention.

Claims

1. A battery pack, characterized in that: The battery pack has: A battery cell configured to be charged by a charging current from a charger; a storage unit configured to store a maximum current variation of the charging current during charging control; a target current calculation unit configured to calculate a target current value which is a control target value of the charging current supplied to the battery cell, and further configured to calculate a value obtained by adding the target current value calculated last time to the maximum current change as a new target current value; and an information notifying unit configured to notify the charger of charging condition information including the new target current value, The maximum current variation is determined according to the characteristics of the battery pack. The maximum current variation is determined based on the characteristics of the battery cell. The characteristics of the battery cell include the impedance of the battery cell, The maximum current change amount is set so that a voltage change amount calculated by multiplying the impedance by the maximum current change amount is smaller than a difference between a charge end voltage value and a charge voltage target value.

2. The battery pack according to claim 1, characterized in that: The battery cell structure comprises: a plurality of cells connected in parallel, The characteristics of the battery cell include a parallel connection state of the plurality of cells.

3. The battery pack according to claim 1 or 2, characterized in that: The storage battery pack includes an operation information acquisition unit configured to: acquire charging operation information related to the charging operation of the charger from the charger; The charging action information includes: information about the charging current output by the charger to the battery pack; The target current calculation unit may calculate the new target current value by using the charging current of the charging operation information instead of the target current value calculated last time.

4. The battery pack according to claim 1 or 2, characterized in that: The battery pack includes a cell voltage comparison unit configured to compare the cell voltage of the battery cell with a target value of the cell voltage in the battery cell during charging, that is, a charging voltage target value, to determine whether the cell voltage is less than the charging voltage target value. The target current calculation unit calculates the new target current value by adding the maximum current change amount to the target current value calculated last time, based on the determination by the cell voltage comparison unit that the cell voltage is less than the charging voltage target value.

5. The battery pack according to claim 4, characterized in that: The target current calculation unit calculates the new target current value by subtracting the maximum current change amount from the target current value calculated last time, based on the cell voltage comparison unit determining that the cell voltage is greater than the charging voltage target value.

6. The battery pack according to claim 1 or 2, characterized in that: The battery pack includes a charging current comparison unit. The charging current comparison unit is configured to compare a provisional current value with a current reference value, and determine whether the provisional current value is below the current reference value, wherein the provisional current value is a value obtained by adding the maximum current change amount to the target current value at the previous calculation, and the current reference value is an upper limit value of the charging current allowed in the battery cell during charging. The target current calculation unit calculates the new target current value by adding the maximum current change amount to the target current value in the previous calculation, based on the judgment by the charging current comparison unit that the provisional current value is below the current reference value. Furthermore, the target current calculation unit sets the current reference value as the new target current value in response to the charging current comparison unit determining that the provisional current value is greater than the current reference value.

7. A charging system comprising a battery pack and a charger, characterized in that: The battery pack is a battery pack according to any one of claims 1 to 6, The charger has: a current output unit configured to output the charging current; a condition information acquisition unit configured to acquire the charging condition information from the storage battery pack; and An output current setting unit is configured to set the charging current output from the current output unit, and the output current setting unit is further configured to set the charging current based on the new target current value, wherein the new target current value is a current value based on the charging condition information.

8. The charging system according to claim 7, characterized in that: The charger includes an output current comparison unit. The output current comparison unit is configured to compare the new target current value with an output current upper limit value to determine whether the new target current value is below the output current upper limit value, wherein the output current upper limit value is an upper limit value of the charging current determined according to the temperature of the charger, the output current setting unit sets the new target current value as the charging current based on the output current comparison unit determining that the new target current value is below the output current upper limit value, The output current setting unit sets the output current upper limit value as the charging current in response to the output current comparison unit determining that the new target current value is greater than the output current upper limit value.

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