Semiconductor device

Abstract

Embodiments of the present disclosure relate to a semiconductor device. The semiconductor device includes a controller configured to control charging of a battery cell. When the battery cell is charged, the controller generates a voltage command value indicating a charger such that an upper limit value of an output voltage output from the charger is higher than a predetermined voltage, the predetermined voltage being a maximum potential voltage at which the battery cell can be charged to the maximum extent.

Description

[0001] Cross Reference to Related Applications

[0002] Japanese Patent Application No. 2019-132492 filed on July 18, 2019, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. BACKGROUND

[0003] The present disclosure relates to a semiconductor device. A battery pack is mounted in applications such as a notebook computer, a tablet terminal, a smart phone, and a digital camera. A battery pack, a semiconductor device for a battery control IC (FGIC: fuel gauge IC) for performing charge / discharge control, and the like are provided. For example, Japanese Unexamined Patent Application Publication No. 2017-204485 discloses a battery pack including such a battery control IC. Full charge is a state in which a battery cell is charged to a voltage close to a maximum potential MaxV that can be charged. In a typical charging scheme, first, constant current charging is performed until the output voltage of a charger reaches MaxV. Thereafter, in order to prevent overvoltage, the output voltage of the charger is set to MaxV, and constant voltage charging is performed until the voltage CellV of the battery cell becomes a voltage close to the desired MaxV. SUMMARY

[0004] During the constant voltage period, the output current is determined by the potential difference between the output voltage (MaxV) of the charger and the internal voltage of the battery cell CellINV. Due to the path impedance from the charger to the battery cell, a voltage drop occurs. When charging with the output voltage set to Max, the battery cell voltage Vcell becomes less than MaxV. Therefore, the battery cell voltage does not reach the maximum potential MaxV, and the output current is less than the maximum current within the safe range. Therefore, the charging time becomes long.

[0005] Other objects and novel features will become apparent from the description and drawings.

[0006] A semiconductor device of a plurality of embodiments is described in this specification. One semiconductor device of one embodiment will be described below.

[0007] A semiconductor device includes a controller configured to control charging of a battery cell. The controller generates a voltage command value indicating a charger such that an upper limit value of an output voltage output from the charger is higher than a predetermined voltage that is a maximum potential voltage at which the battery cell can be charged to the maximum extent. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is an exemplary configuration diagram illustrating a battery charger system according to a first embodiment.

[0009] Figure 2 is an explanatory diagram showing an example of a process related to charging of a battery charging system according to the first embodiment.

[0010] Figure 3 is an explanatory diagram showing an example of a process related to charging of a battery charging system according to the second embodiment.

[0011] Figure 4 is a flowchart showing an example of a method of calculating a path impedance and a command value of an output voltage according to the second embodiment.

[0012] Figure 5 is a flowchart showing an example of a method of calculating a path impedance and a command value of an output voltage according to the third embodiment.

[0013] Figure 6 is an explanatory diagram showing an example of a process related to charging of a battery pack according to the fourth embodiment.

[0014] Figure 7 is a flowchart showing details of step S106 in Figure 6

[0015] Figure 8A and Figure 8B is a diagram showing an example of a calculation in step S106.

[0016] Figure 9 is an explanatory diagram showing an example of a process related to charging of a conventional battery cell.

[0017] Figure 10 is a schematic diagram illustrating a path impedance between a charger and a battery cell.

[0018] Figure 11A and Figure 11B is a schematic diagram showing a charging voltage of a battery pack, a voltage of a battery cell, and a charging current at the time of charging. DETAILED DESCRIPTION

[0019] Supplementary information on the problem

[0020] Before describing the present embodiment, a process of charging a conventional battery pack will be described. Figure 9 is an explanatory diagram illustrating an example of a process related to charging of a conventional battery pack. In Figure 9 , operations of an FGIC (semiconductor device) 20 in the battery pack and a charger 90 are shown, respectively.

[0021] ​In step S101, the FGIC 20 measures the voltage of the battery cell, the current (including the output current) in the battery pack 100, the temperature in the battery pack 100, and the like. Note that the temperature measurement in the battery pack 100 includes the temperature measurement of the battery cell.

[0022] In step S103, the FGIC 20 sets a command value CC (charge current; current command value) and a command value CV (charge voltage; voltage command value) based on the voltage, current, and temperature and the like measured in step S101, respectively, where the command value CC is used to define the upper limit value of the output current Iout supplied from the charger 90 to the battery cell, and the command value CV is used to define the upper limit value of the output voltage Vout. Generally, the command value CV of the output voltage Vout is set to MaxV. At the same time, the charger 90 transmits a connection confirmation signal via communication such as SMBus communication. Thus, the charger 90 confirms the connection state with the battery pack (step S201).

[0023] When the battery pack 100 is connected to the charger 90, the battery pack 100 transmits a response signal for the connection confirmation signal via the communication device. Thus, when the battery pack 100 and the charger 90 are connected to transition to the charging mode, the FGIC 20 transmits the output current command value CC and the output voltage command value CV set in step S103 to the charger 90 (step S105).

[0024] The charger 90 sets the upper limit values of the output current and the output voltage for charging based on the command values CC and CV received from the battery pack 100, respectively (step S203). Then, the charger 90 charges the battery pack based on the upper limit values set in step S203 (step S205).

[0025] During charging, the FGIC 20 measures the battery cell voltage Vcell, the charging current Ic flowing in the battery pack 100, the temperature in the battery pack 100, and the like (step S107).

[0026] Then, in step S109, the FGIC 20 judges whether the battery cell is in a fully charged state and whether a charging abnormality is detected based on the battery cell voltage Vcell, the charging current Ic, and the temperature measured in step S107. If the battery cell is not fully charged and no abnormality is detected, the FGIC 20 executes the process of step S107 again. That is, in this case, the charging of the battery pack 100 is continued.

[0027] On the other hand, if the battery cell is in a fully charged state or an abnormality is detected (Yes), the FGIC 20 ends charging of the battery pack 100 (step Slll). For example, the FGIC 20 transmits a charge end signal to the charger 90, which ends charging of the battery pack 100. After receiving the charge end signal, the charger 90 stops supplying power to the battery pack 100, and terminates charging (step S207).

[0028] Figure 10 is a diagram illustrating path impedances between the charger and the battery cell. Figure 11A and Figure 11B is a diagram illustrating output voltage, battery cell voltage, and output current when charging the battery pack. Figure 11A shows waveforms of a conventional actual voltage and current, and Figure 11B shows waveforms of an ideal voltage and current.

[0029] As shown in Figure 10 , there are two path impedances in the charging path. A path impedance (first path impedance) Rsys from the charger 90 to the end of the battery pack 100 and a path impedance (second path impedance) Rpack from the end of the battery pack 100 to the battery cell. Therefore, in the charging path, a voltage drop IR-Drop occurs due to the path impedances Rsys and Rpack. However, in the conventional charging method, the command value CV has been set without considering the voltage drop IR-Drop due to the path impedances. Therefore, as shown in Figure 11A , at time Tl, the battery cell voltage is switched from constant current charging to constant voltage charging in a state much lower than MaxV. In constant voltage charging, since the output current is reduced compared to the ideal waveform as shown in Figure 11B , the charging time becomes long.

[0030] First Embodiment

[0031] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings. In all the drawings used to explain the embodiments, substantially the same parts are denoted by the same reference numerals, and repetitive description thereof is omitted.

[0032] Configuration of the battery pack

[0033] Figure 1 An exemplary configuration of the battery recharging system 1 according to the first embodiment is shown. As shown in Figure 1 , the battery recharging system 1 includes the battery pack 100, the battery cell 10, the charge control transistor 12, the discharge control transistor 14, the current sense resistor 16, the FGIC 20, and the like.

[0034] During charging of the battery cell 10, the battery pack 100 is connected to the charger 90 through the positive terminal P1 and the negative terminal P2, and power for charging is supplied from the charger 90.

[0035] The battery cell 10 is constituted by a secondary battery such as a lithium ion battery. The battery cell 10 can be composed of a plurality of cells, or can be composed of only a single cell. Figure 1 The battery cell 10 formed of a single cell is illustrated. Each cell has a cell body and an internal resistance. Figure 1 Vcell in the battery cell 10. Hereinafter, Vcell is also referred to as a cell voltage. Furthermore, Figure 1 CellINV in the battery cell 10. Hereinafter, CellINV is also referred to as an internal voltage. Figure 1 In the battery cell 10, the cell voltage Vcell is a voltage drop from the internal voltage CellINV according to the internal resistance of the cell.

[0036] The charge control transistor 12 is a circuit element that mainly performs current control during charging of the battery cell 10. For example, the charge control transistor 12 is constituted by a field effect transistor such as an NMOS. The gate of the charge control transistor 12 is connected to the FGIC 20 as shown in Figure 1 The charge control transistor 12 is turned on / off by gate voltage control from the FGIC 20.

[0037] The discharge control transistor 14 is a circuit element that controls current during discharging of the battery cell 10, that is, during power supply to a load (not illustrated). The discharge control transistor 14 is constituted by a field effect transistor such as an NMOS. The gate of the discharge control transistor 14 is connected to the FGIC 20. The discharge control transistor 14 is turned on / off by gate voltage control from the FGIC 20.

[0038] The current sense resistor 16 is a circuit element for detecting a current flowing into the battery pack 100. The current sense resistor 16 is connected to the FGIC 20, and the current is measured by the current value measuring unit 21 in the FGIC 20.

[0039] As shown in Figure 1 The FGIC 20 includes a current value measuring unit 21, a voltage value measuring unit 23, a temperature measuring unit 22, a ROM (Read Only Memory) 25, a charge / discharge controller (controller) 27, and the like.

[0040] The current value measurement unit 21 is a functional block for measuring the current value of the current flowing through the current sense resistor 16. The current value measurement unit 21 includes, for example, a current value measurement circuit and an AD converter. The current value measurement unit 21 digitally converts the current value measured by the current value measurement circuit by the AD converter, and outputs the digitized current value. The measured current value is used in the calculation in the charge / discharge controller 27. The current value is stored in the ROM 25.

[0041] The voltage value measurement unit 23 is a functional block for measuring the voltage of the battery pack 100, such as the terminal voltage Vpack or the cell voltage Vcell, for example. When the battery cell 10 is composed of a plurality of cells, the voltage value measurement unit 23 can measure the voltage of each cell. The voltage value measurement unit 23 includes, for example, a voltage value measurement circuit and an AD converter. The voltage value measurement unit 23 digitally converts the voltage value measured by the voltage value measurement circuit by the AD converter, and outputs the digitized voltage value. The measured voltage value is used in the calculation in the charge / discharge controller 27. The voltage is stored in the ROM 25.

[0042] The temperature measurement unit 22 is a functional block for measuring the temperature in the battery pack 100, such as the battery cell 10. The temperature measurement unit 22 is, for example, a temperature sensor (e.g., a resistance for temperature measurement), a temperature measurement circuit, an AD converter, and the like. The temperature measurement unit 22 includes, for example, a temperature table or a temperature function in which the resistance value of the temperature measurement resistance is associated with the temperature, and the temperature in the battery pack 100 is measured using the resistance value of the temperature measurement resistance measured by the temperature measurement circuit. The measured temperature information is used to detect the abnormality of the battery cell 10 in a high-temperature state, for example. When the high-temperature state is detected, the charge / discharge controller 27 stops charging and discharging.

[0043] The ROM 25 stores various types of information, such as an operation program and setting information related to the battery pack 100. The ROM 25 can be composed of a flash memory or a register or the like, or a combination of both. As shown in Figure 1 For example, the ROM 25 has respective storage areas for storing a program 25A related to the control of the battery pack 100, setting information 25B, a measured temperature 25C, a measured current value 25D, and a measured voltage value 25E, and the like, as shown in

[0044] The ROM 25 stores the path impedance (first path impedance) Rsys and the path impedance (second path impedance) Rpack as setting data 25B. The ROM 25 also stores the command values CC and CV as setting data 25B to the charger 90, respectively. As the command value CC, for example, a predetermined value of the output current allowed when constant current charging is performed is stored. Further, as the charging voltage CV, for example, a value of the maximum potential MaxV of the battery cell 10 is stored. These values can be temporarily stored in a RAM (not shown) or the like during charging.

[0045] The charge / discharge controller 27 is a functional block for controlling processes related to charging and discharging of the battery cell 10. When charging the battery cell 10, for example, the charge / discharge controller 27 controls each cell in the battery pack 100 in accordance with a flow to be described later (such as Figure 9 and Figure 2 ). Further, the charge / discharge controller 27 sets the command values CC and CV based on the current value obtained by the current value measuring unit 21, the voltage value obtained by the voltage value measuring unit 23, and the temperature value obtained by the temperature measuring unit 22, determines whether to continue charging, and the like.

[0046] The charge / discharge controller 27 is composed of, for example, a processor such as a CPU, a separate circuit for implementing each functional block, or the like. In addition, the FGIC 20 can be composed of an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The FGIC 20 can be configured by combining them.

[0047] The manner in which the battery pack is charged in the present embodiment

[0048] Figure 2 is an explanatory diagram showing an exemplary process related to charging of the battery pack according to the first embodiment. Figure 2 Similar to the previously described Figure 9 . Thus, in Figure 2 , the steps for performing the same processing as in Figure 9 are designated by the same reference numerals. The following description focuses on the processing that is different from Figure 9

[0049] In Figure 2 , a step S108 is added to the battery pack 100 with respect to Figure 9 . The process in the step S203 is partly different from that in Figure 9

[0050] ​​In step S108, a command value CV that takes into account the voltage drop IR-Drop due to the path impedance is set. Specifically, the charge / discharge controller 27 generates the command value CV that indicates that the maximum value of the output voltage Vout output from the charger 90 is a predetermined voltage higher than the maximum potential MaxV at which the battery cell 10 can be charged to the maximum extent.

[0051] The charge / discharge controller 27 sets the command value CV again on the basis of the voltage of the battery cell 10 measured in step S107 and the charge current Ic in the battery pack 100. For example, when the battery cell voltage Vcell is lower than the desired voltage, the charge / discharge controller 27 sets the value of the command value CV of the output voltage Vout to a value higher than the current value again. At this time, the charge / discharge controller 27 can change the command value CV by a predetermined width defined in advance, and can change the command value CV at the time of referring to the corresponding value measured in step S107. The charge / discharge controller 27 transmits the command value CV set again to the charger 90.

[0052] In step S203, once the command value CV reconfigured is received from the FGIC 20, the charger 90 updates the upper limit value of the output voltage Vout from MaxV to the received charge voltage CV. When the constant voltage charging is performed, the charger 90 supplies the output voltage Vout based on the upper limit value set again to the battery pack 100 (step S205).

[0053] During the charging, the processes of steps S107 to S108 are repeatedly performed. In correspondence thereto, the command value CV is periodically updated in step S203.

[0054] Main effects of the embodiment

[0055] According to the embodiment, the command value CV of the output voltage Vout of the charger 90 is set to a value that takes into account the voltage drop due to the path impedance. According to this configuration, during the constant voltage charging, since the voltage of the output voltage Vout is maintained at a value greater than MaxV, even if the battery cell voltage Vcell becomes close to MaxV, it is possible to maintain a state in which the potential difference between the output voltage Vout and the battery cell Vcell is large. Therefore, it is possible to increase the charge current Ic, and as a result, it is possible to shorten the charging time. In other words, it is possible to extend the transition time from the constant current charging to the constant voltage charging, and to maximize the output current within a safe range to shorten the charging time.

[0056] Further, according to the embodiment, since the command value CV is set so that the battery cell voltage Vcell does not exceed MaxV, it is possible to ensure the safety during the charging.

[0057] Second Embodiment

[0058] Next, a second embodiment will be described. This embodiment describes a manner of setting the command value CV of the output voltage Vout while updating the path impedances Rpack, Rsys.

[0059] Figure 3 is a diagram showing an exemplary procedure related to charging of the battery pack according to the second embodiment. Figure 3 Similarly to Figure 2 and Figure 2 the difference is that a step S102 is added between steps S101 to S103.

[0060] In step S102, an initialization value preset in the path impedances Rsys, Rpack is set. This setting is performed only once after the FGIC 20 is started. The path impedances Rsys, Rpack are measured by, for example, the method shown in Figure 4 which will be described later. The measured path impedances Rsys, Rpack can be stored in the ROM 25 as the initial values, or can be temporarily stored in a random access memory RAM (not shown).

[0061] In step S103, the same procedure in Figure 2 and Figure 9 may be performed, or the command values CC and CV can be calculated using the initialization values of the path impedances Rsys, Rpack set in step S102. The command value CV is calculated at the charge / discharge controller 27 by Equation (3) which will be described later. In step S105, the command value CV calculated here is transmitted to the charger 90.

[0062] In step S108 of this embodiment, the procedure shown in Figure 4 is performed. Figure 4 is a flowchart showing an exemplary method of calculating the path impedances and the command value of the output voltage according to the second embodiment. Figure 4 Steps S108a, S108b, and S108c are included. In step S108a, the path impedance Rpack from the end of the battery pack 100 to the battery cell is calculated. Specifically, the charge / discharge controller 27 calculates the path impedance Rpack using the end voltage Vpack of the battery pack 100, the battery cell voltage Vcell, and the charging current Ic by Equation (1) in Figure 4

[0063] ​In step S108b, the path impedance Rsys from the charger 90 to the end of the battery pack 100 is calculated. Specifically, the charge / discharge controller 27 calculates the path impedance Rsys by using the output voltage Vout of the charger 90, the end voltage Vpack of the battery pack 100, and the charge current Ic through Equation (2) in Figure 4 The output voltage Vout can be received from the charger 90 via the communication device.

[0064] In step S108c, the charge / discharge controller 27 adds the respective path impedances Rpack, Rsys calculated in steps S108a and S108b to calculate the path impedance (Rpack+Rsys) from the charger 90 to the battery cell 10. Then, the charge / discharge controller 27 calculates the command value CV of the output voltage Vout by using the path impedance (Rpack+Rsys) and the charge current Ic, etc. through Equation (3) in Figure 4 Accordingly, in the present embodiment, the charge / discharge controller 27 calculates the command value CV taking into account the voltage drop IR-Drop using the calculated path impedances Rpack, Rsys and the charge current Ic. In other words, the command value CV is set to a value corresponding to the voltage obtained by adding the maximum chargeable voltage MaxV of the battery cell 10 to the voltage drop due to the path impedance Rpack, Rsys from the charger 90 to the battery cell 10. The other processes are the same as those of the above-described embodiment.

[0065] In step S108, only one of the path impedances Rpack, Rsys can be measured. In other words, only one of steps S108a, S108b in Figure 4 is executed. For the path impedance not calculated in step S108, the process of step S108c is executed using, for example, an initialized value set in step S102, a value calculated in the previous step S108, etc.

[0066] Alternatively, steps S108b, S108c can be combined to directly calculate the combined resistivity of the path impedances Rpack, Rsys. Specifically, the charge / discharge controller 27 calculates the combined resistance value (Rpack+Rsys) using the output voltage Vout (command value CV), the battery cell voltage Vcell, and the charge current Ic.

[0067] Main effects of the present embodiment

[0068] According to the present embodiment, the path impedances Rpack, Rsys measured for each cycle are used to set the command value CV of the output voltage Vout using the charge current Ic. According to this configuration, the voltage applied to the battery cell 10 can be adjusted to a more appropriate value.

[0069] Third Embodiment

[0070] Next, the third embodiment will be described. In this embodiment, the path impedance Rsys from the charger 90 to the end of the battery pack 100 is updated only when it is constant voltage charging.

[0071] Figure 5 is a flowchart showing an exemplary method of calculating the path impedance and the command value of the output voltage according to the third embodiment. In Figure 5 Step S108 of this embodiment shown in Figure 4 is similar to step S108 in Figure 4 the difference from step S108 in

[0072] In step S108d, the charging method is determined to be constant current charging or constant voltage charging. Such determination is performed using the charging current Ic and the like measured in step S107. The charge / discharge controller 27 determines by comparing the command value CC minus the charging current Ic in the output current Iout of the charger 90 with a threshold current Ith. Here, the threshold current Ith is a reference value for determining whether it is constant current charging or constant voltage charging.

[0073] First, the charge / discharge controller 27 calculates the value of the command value CC minus the charging current Ic. Then, the charge / discharge controller 27 compares the calculated value obtained by subtracting the charging current Ic from the command value CC with the threshold current Ith. As a result of these comparisons, when the relationship of the following equation (4) is satisfied, the charge / discharge controller 27 judges that the charging current Ic is decreasing, and it is constant voltage charging. Thereafter, the charge / discharge controller 27 sequentially performs the processes of steps S108b, S108c.

[0074] That is, when it is judged to be constant voltage charging, the path impedance Rsys from the charger 90 to the end of the battery pack 100 is recalculated, and the command value CV is updated using the recalculated path impedances Rpack, Rsys.

[0075] Command value CC - Ic > threshold current Ith... Equation (4)

[0076] On the contrary, if the relationship of the equation (4) is not satisfied, the charge / discharge controller 27 judges that the charging current Ic is not decreasing, and it is constant current charging. Thereafter, the charge / discharge controller 27 only performs the process of S108c.

[0077] That is, when it is determined to be constant current charging, the path impedance Rsys from the charger 90 to the end of the battery pack 100 is not recalculated, and the command value CV is updated using, for example, the initial value of the path impedance Rsys that has been described and the path impedance Rpack calculated through step S108a.

[0078] Once the determination is made in step S108d, the charge / discharge controller 27 can compare the value obtained by subtracting the charging current Ic from the command value CC with the threshold current Ith a plurality of times, and when the relationship of equation (4) is satisfied for a predetermined time, it can be judged to be constant voltage. Further, the charge / discharge controller 27 can compare the value obtained by subtracting the charging current Ic from the command value CC with the threshold current Ith a plurality of times, and when the relationship of equation (4) is satisfied at a predetermined ratio or more consistently, it can be judged to be constant voltage.

[0079] Main effects of the present embodiment

[0080] According to the present embodiment, the update of the path impedance Rsys is performed only when it is determined to be constant voltage charging. According to this configuration of the present embodiment, when the path impedance Rsys is measured, the output voltage Vout is replaced with the command value CV. According to this configuration, even when the output voltage Vout cannot be directly measured at the FGIC 20, the path impedance Rsys can be measured.

[0081] Fourth embodiment

[0082] Next, a fourth embodiment will be described. In the present embodiment, a method of estimating the change in the charging current Ic and the output current Vout from the start to the end of charging before charging and a method of updating the command values CC, CV based on the estimation result will be described.

[0083] Figure 6 is a explanatory diagram showing an exemplary process related to battery pack charging according to the fourth embodiment. Figure 6 Similar to Figure 2 and different from Figure 2 is that step S106 is added between steps S105 to S107. Figure 7 is a flowchart showing the details of S106 in Figure 6 Figure 8A and Figure 8B is a schematic diagram illustrating exemplary estimations in S106. In Figure 8A , an example of estimating the output current Iout, the output voltage Vout, and the cell voltage Vcell is shown. In Figure 8B , an example of estimating the battery temperature, the FET temperature, and the wiring temperature is shown.

[0084] ​Step S106 is a step of estimating the variation of the charging current Ic, the output current Vout. As shown in FIG. 8, step S106 includes steps S106a to S106f. Figure 4

[0085] In step S106a, the Joule heat and the heat radiation generated in the battery pack 100 at the time of charging are calculated. The charging / discharging controller 27 calculates the Joule heat and the heat dissipation at the time tO immediately after the start of charging based on, for example, the command values CC, CV set in step S102 (see FIG. 8). The ROM 25 stores various types of information required for the calculation of, for example, the specific heat, the heat capacity, the thermal conductivity, the resistivity, and the like of the main components of the battery pack 100 as the setting information 25B. The key components mentioned herein include, for example, the battery cells 10, the charging control transistor 12 and the discharging control transistor 14 (sometimes collectively referred to as "FETs"), the resistors connected to these transistors, the wiring from the charger 90 to the battery cells 10, and the like. The charging / discharging controller 27 calculates the Joule heat and the heat dissipation using the current command value CC as the current, the command value CV as the voltage, and the setting information 25B in the ROM 25.

[0086] In step S106b, the temperature in the battery pack 100 is calculated. The charging / discharging controller 27 calculates the temperature of the battery cells 10, the FETs, the wiring, and the like at the time tO using the Joule heat, the heat radiation calculated in step S106a, and the setting information 25B. The calculated battery temperature, FET temperature, and wiring temperature are shown in FIG. 9, respectively. Figure 8B

[0087] In step S106c, the path impedances Rpack, Rsys and the internal resistance of the battery cells 10 are calculated. The charging / discharging controller 27 calculates the path impedances Rpack, Rsys and the internal resistance of the battery cells 10 at the time tO using the temperature of each cell calculated in step S106b and the setting information 25b.

[0088] In step S106d, the internal voltage CellINV of the battery cells 10 and the battery cell voltage Vcell are calculated. The charging / discharging controller 27 calculates the internal voltage CellINV and the battery cell voltage Vcell at the time tO using, for example, the path impedances Rpack, Rsys calculated by step S106c and information such as the internal resistance, the temperature, and the like of the battery cells 10. Incidentally, the charging / discharging controller 27 can further use the command values CC, CV as needed to calculate the internal voltage CellINV and the battery cell voltage Vcell.

[0089] ​​In step S106e, the output current Iout and the output voltage Vout of the charger 90 are calculated. The charge / discharge controller 27 calculates the output current Iout (or the charging current Ic) and the output voltage Vout at the time t0 using the path impedance Rpack, Rsys calculated in step S106c, the internal resistance of the battery cell 10, and the internal voltage CellINV calculated in step S106d, the battery cell voltage Vcell, and the like.

[0090] In step S106f, the charge / discharge controller 27 determines whether the output current Iout and the battery cell voltage Vcell calculated in step S106e satisfy the charge termination condition, respectively. When the battery cell voltage Vcell and the output current Iout satisfy the charge end condition, respectively, the charge / discharge controller 27 finally determines that the charge end condition is satisfied.

[0091] Specifically, when the calculated battery cell voltage Vcell is greater than a predetermined threshold value Vpth close to MaxV, the charge / discharge controller 27 determines that the charge end condition is satisfied for the battery cell voltage Vcell. The threshold value Vpth can be a value smaller than the threshold value MaxV. Then, if the calculated output current Iout is smaller than a predetermined threshold value Ipth, the charge / discharge controller 27 determines that the charge end condition is satisfied for the output current Iout.

[0092] If at least one of the battery cell voltage Vcell and the output current Iout does not satisfy the charge end condition (No), the charge / discharge controller 27 determines that the charge end condition is not satisfied, and the processes of steps S106a to S106e are executed again.

[0093] In steps S106a to S106e again, for example, the respective values at the time t1 in FIG. 8 are calculated. These processes are repeatedly executed until the time tn at which the charge end condition is satisfied is estimated as being fully charged (FIG. 8), thereby obtaining time series information of each of the calculated values.

[0094] When both the battery cell voltage Vcell and the output current Iout satisfy the charge end condition (Yes), the charge / discharge controller 27 determines that the charge end condition is satisfied, and ends the processes of step S106.

[0095] According to FIGS. 8a and 8b, when the charging is started, the battery pack voltage Vcell and the temperature of each component in the battery pack 100 increase. During this time, the output voltage Vout, the output current Iout are substantially constant. And at a predetermined timing after the time t3, the output current Iout decreases. Further, the calculated output current Iout at the time tn decreases below the threshold value Ipth. At the same time, the output voltage Vout is slightly lower than the output voltage at the time of starting the charging, and the output voltage does not decrease much.

[0096] Then, when the output current Iout decreases, the temperature increase of each component in the battery pack 100 is substantially suppressed.

[0097] At the time t2, the calculated battery cell voltage Vcell rises to a voltage equal to or greater than the threshold value Vpth and equal to or less than MaxV. Thereafter, until the time tn, the value of the calculated battery cell voltage Vcell becomes a substantially constant value, or slowly increases in a range lower than MaxV.

[0098] The charge / discharge controller 27 transmits the output current Iout and the output voltage Vout calculated in the step S106 to the charger 90 as the command values CC, CV at a predetermined timing corresponding to FIG. 8, respectively. Since the command value CV is also transmitted in the step S108 at the later stage, in the step S106, only the command value CC based on the calculated output current Iout can be transmitted.

[0099] Main effects of the present embodiment

[0100] According to the present embodiment, since the change in the output current Iout and the output voltage Vout from the charger 90 can be estimated before the charging is started, the command values corresponding to the calculated output current Iout and the calculated output voltage Vout can be set. Further, even if the charger which cannot perform the constant voltage charging, by transmitting the command value CC corresponding to the calculated output current Iout, the safety at the time of charging is ensured.

[0101] Incidentally, the charge / discharge controller 27 or the like measures the time which defines the timing for transmitting the command values CC and CV. For the measurement of the time, a counter circuit and a timer circuit (not shown) can be used, or a method such as a decrement count using a register can be employed.

[0102] While the present application made by the present inventor has been specifically described based on the embodiments, the present application is not limited to the above-described embodiments, and needless to say, various modifications can be made without departing from the spirit of the present application.

Claims

1. A semiconductor device comprising: a controller configured to control charging of a battery cell, wherein the controller generates a voltage command value indicating that an output voltage output from a charger is to have an upper limit value higher than a predetermined voltage that is a maximum potential voltage at which the battery cell can be charged to the maximum extent, wherein the controller generates the voltage command value so that a voltage value obtained by adding the maximum potential voltage at which the battery cell can be charged to the maximum extent and a voltage drop value due to a path impedance between the charger and the battery cell is to be the upper limit value of the output voltage, and wherein the controller: calculates a first path impedance between the charger and an end voltage of the battery pack by using the output voltage of the charger, the end voltage of the battery pack, and a charging current flowing through the battery pack, calculates a second path impedance between the end of the battery pack and the battery cell by using the end voltage of the battery pack, the voltage of the battery cell, and the charging current flowing through the battery pack, calculates the path impedance by adding the first path impedance and the second path impedance, and calculates the voltage drop value by using the path impedance and the charging current flowing through the battery pack, wherein a charging method includes constant current charging and constant voltage charging, the controller determines whether the constant current charging or the constant voltage charging by comparing a value obtained by subtracting the charging current from a current command value indicating an upper limit value of an output current of the charger with a threshold current, and wherein the controller updates the first path impedance only when the charging method is the constant voltage charging.

2. The semiconductor device according to claim 1, wherein the controller calculates the voltage drop value by using the output voltage from the charger, the voltage of the battery cell, and the charging current flowing through the battery pack.

3. The semiconductor device according to claim 1, wherein the controller periodically updates the voltage command value.

4. The semiconductor device according to claim 3, wherein the constant current charging performs charging of a constant current until the output voltage of the charger reaches the maximum potential voltage at which the battery cell can be charged to the maximum extent, and after the constant current charging, constant voltage charging sets the output voltage from the charger to the maximum potential voltage, and then, performs constant voltage charging until the voltage of the battery cell approaches the maximum potential voltage.

5. The semiconductor device according to claim 1, wherein the controller calculates the path impedance using the output voltage as a voltage corresponding to the voltage command value.

6. The semiconductor device according to claim 2, wherein the controller: estimates a change in the charging current and the output voltage before the charging is started, and At the time of charging, based on an estimation result of the changes in the charging current and the output voltage, a current command value, which indicates an upper limit value of an output current from the charger to the charger, and the voltage command value are updated.

7. The semiconductor device according to claim 6, wherein The controller estimates changes in the charging current and the output voltage from the start of charging to the end of charging.

8. The semiconductor device according to claim 6, wherein The controller: calculates a joule heat amount generated in the battery pack and a heat loss amount, calculates a temperature in the battery pack using a calculated value of the joule heat amount and a calculated value of the heat loss amount, calculates the path impedance using a calculated value of the temperature in the battery pack, and calculates an internal voltage of the battery cell and a voltage of the battery cell by using the calculated path impedance; and estimates changes in the charging current and the output voltage by using the calculated internal voltage of the battery cell.

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