Semiconductor device and battery charge control method

Abstract

To provide a semiconductor device capable of stably estimating an internal temperature of a battery.SOLUTION: A semiconductor device coupled to a battery calculates entropy heat of the battery at a predetermined time by using a charging current of the battery and an internal temperature of the battery at a time before a predetermined time in a step S1, calculates a heat generation amount of the battery from the charging current of the battery in a step S2, calculates a heat radiation amount of the battery on the basis of, a temperature difference between the internal temperature at the time before the predetermined time and a surface temperature of the battery in a step S3, and estimates the internal temperature of the battery at the predetermined time by using the entropy heat, the heat generation amount and the heat radiation amount in a step S4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device and a method for controlling charging of a battery, and more particularly to a semiconductor device for charging a battery (secondary battery) such as a lithium ion battery, and a method for controlling charging when charging the battery. [Background technology]

[0002] For example, Patent Document 1 describes a technique for measuring the surface temperature of a battery and the temperature of the external environment in which the battery exists (environmental temperature) and controlling the charging of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 038658 Summary of the Invention [Problem to be solved by the invention]

[0004] When the temperature difference between the battery's surface temperature and the ambient temperature is large, it is effective to use the ambient temperature to estimate the battery's internal temperature, as shown in Patent Document 1, for example. However, due to the structure of the battery, the temperature difference between the battery's surface temperature and the ambient temperature is usually small, and the ambient temperature does not contribute to estimating the battery's internal temperature. Therefore, it is conceivable to estimate the battery's internal temperature using the surface temperature and control the battery charging based on the surface temperature and the estimated internal temperature. However, in this case, depending on the battery's usage conditions, for example, the surface temperature may be higher than the ambient temperature, making it difficult to accurately estimate the battery's internal temperature using the surface temperature.

[0005] Patent Document 1 neither describes nor suggests how to correctly estimate the internal temperature of a battery without using the environmental temperature. [Means for solving the problem]

[0006] A brief summary of a representative embodiment of the present invention will be given below.

[0007] That is, the semiconductor device coupled to the battery is supplied with the battery's charging current, battery voltage, and battery surface temperature, and includes a control unit that estimates the battery's internal temperature, and a memory that stores the internal temperature estimated by the control unit. Here, the control unit calculates the entropy heat of the battery at a predetermined time using the supplied charging current and the internal temperature at a time before the predetermined time stored in the memory, calculates the amount of heat generated by the battery from the supplied charging current, determines the temperature difference between the internal temperature at the previous time stored in the memory and the supplied surface temperature, calculates the amount of heat dissipated by the battery from the temperature difference, and estimates the battery's internal temperature at the predetermined time using the calculated entropy heat, the amount of heat generated, and the amount of heat dissipated.

[0008] In addition, in a semiconductor device according to another embodiment, the charging current when charging the battery is determined based on the estimated internal temperature.

[0009] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Effects of the Invention]

[0010] According to one embodiment, it is possible to stably estimate the internal temperature of a battery using the surface temperature of the battery, without using the uncertain ambient temperature of the battery. [Brief explanation of the drawings]

[0011] [Figure 1] 4 is a flowchart illustrating an internal temperature estimation process according to the first embodiment. [Figure 2] 1 is a partial perspective view showing an example of a battery pack according to a first embodiment. [Figure 3] FIG. 4 is a diagram showing mathematical expressions used in the internal temperature estimation process according to the first embodiment. [Figure 4] FIG. 10 is a block diagram showing the configuration of a charging system according to a second embodiment. [Figure 5] 10 is a flowchart for explaining the overall operation of the charging system according to the second embodiment. [Figure 6] 10 is a flowchart showing the operation of the charging system according to the second embodiment. [Figure 7] FIG. 10 is a characteristic diagram showing characteristics during charging in Comparative Example 1. [Figure 8] FIG. 10 is a characteristic diagram showing characteristics during charging in Comparative Example 2. [Figure 9] FIG. 10 is a characteristic diagram showing characteristics during charging in Comparative Example 3. [Figure 10] FIG. 10 is a characteristic diagram showing characteristics during charging in Comparative Example 4. [Figure 11] FIG. 10 is a characteristic diagram showing the characteristics of the charging system according to the second embodiment. [Figure 12] 10 is a flowchart showing the operation of the charging system according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, various embodiments of the present invention will be described with reference to the drawings. Note that the disclosure is merely an example, and any appropriate modifications that can be easily conceived by a person skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention.

[0013] Furthermore, in this specification and each drawing, elements similar to those previously described with respect to the previous drawings are given the same reference numerals, and detailed descriptions thereof may be omitted as appropriate.

[0014] (Embodiment 1) In the first embodiment, a process of estimating the internal temperature of the battery based on the surface temperature of the battery (internal temperature estimation process) will be described.

[0015] The internal temperature estimation process is performed in a semiconductor device mounted in the battery pack together with the battery. An example of the semiconductor device will be described later (Embodiment 2), so a detailed description will be omitted here and only the parts necessary for the description will be mainly described.

[0016] Fig. 1 is a flowchart for explaining an internal temperature estimation process according to embodiment 1. Fig. 2 is a partial perspective view showing an example of a battery pack according to embodiment 1. Fig. 3 is a diagram showing mathematical expressions used in the internal temperature estimation process according to embodiment 1.

[0017] In FIG. 2, BTP indicates a battery pack. The battery pack BTP includes a battery configured with one or more battery cells BTC and a substrate Sub on which a semiconductor device and the like are mounted. While FIG. 2 shows an example of a battery configured with one battery cell BTC, the present invention is not limited to this. When a battery is configured with multiple battery cells BTC, the multiple battery cells BTC are connected to each other in series, for example, and each battery cell BTC is coupled to a semiconductor device mounted on the substrate Sub. When the battery pack BTP is coupled to an electronic device (not shown), the discharge voltage of the battery in the battery pack BTP is supplied to the electronic device as a power source.

[0018] When charging the battery in the battery pack BTP, the semiconductor device mounted on the substrate Sub supplies status information (battery status information) related to the coupled battery to a charging device (not shown). The charging device charges the battery based on the supplied status information. Hereinafter, in this specification, a system including the battery pack BTP and the charging device will also be referred to as a charging system.

[0019] 2, Tin indicates the internal temperature of the battery (battery cell BTC), and Ts indicates the surface temperature of the battery (battery cell BTC). Furthermore, Rin indicates the temperature resistance (temperature impedance) of the battery, and Ta indicates the ambient temperature outside the battery (inside the battery pack BTP). The difference between the surface temperature Ts and the ambient temperature Ta is that the surface temperature Ts is the temperature at the surface of the battery, whereas the ambient temperature Ta is the temperature at a predetermined position in the air inside the battery pack BTP.

[0020] In the first embodiment, the surface temperature Ts is measured by a temperature sensor (not shown) placed on the surface of the battery, and is notified to the semiconductor device.

[0021] The semiconductor device includes a memory, a processor core, etc. The memory stores data such as the internal temperature of the battery at a time (past time: past time To) prior to a predetermined time (for example, the current time: current time Tp), the entropy of the battery, and the temperature resistance of the battery. The semiconductor device executes the internal temperature estimation process shown in Fig. 1 using the data stored in the memory, the surface temperature Ts at the current time (Tp) measured by a temperature sensor, the charging current, etc., to estimate the internal temperature Tin of the battery at the current time (Tp).

[0022] Next, the internal temperature estimation process of the battery will be described with reference to Fig. 1. The internal temperature estimation process is realized by a processor core built into the semiconductor device executing a program while using a memory also built into the semiconductor device. That is, steps S0 to S5 in Fig. 1 are performed by the processor core through execution of the program. The internal temperature estimation process starts with step S0. Following step S0, steps S1, S2, and S3 are performed. In the internal temperature estimation process according to the first embodiment, steps S1 to S3 are performed in parallel, but this is not limiting.

[0023] In step S1, the entropy heat Qe of the battery is calculated based on the internal temperature Tin_To at a past time (To) stored in memory, the entropy Ent of the battery at the current time (Tp), and the charging current Crt. In the first embodiment, a plurality of entropies Ent corresponding to the state of charge (SOC) of the battery are stored in the memory as a table (entropy table).

[0024] Step S1 is composed of steps S1_0 and S1_1. In step S1_0, the entropy Ent corresponding to the state of charge (SOC) of the battery at the current time is obtained from the entropy table. That is, the corresponding entropy Ent is calculated from the state of charge of the battery. The calculated entropy Ent is used in the next step S1_1. The entropy Ent is a coefficient corresponding to the state of charge of the battery. The user obtains in advance a plurality of entropies Ent corresponding to different state of charge, and stores them in memory as an entropy table as described above.

[0025] In step S1_1, entropy heat Qe is calculated. The mathematical formula for calculating entropy heat Qe is shown as equation (1) in Fig. 3. As can be understood from equation (1) shown in Fig. 3, entropy heat Qe of a battery is the product of charging current Crt, internal temperature Tin_To at a past time, and entropy Ent.

[0026] In step S2, the amount of heat (Joule heat) Qj of the battery is calculated. The formula for calculating the amount of heat Qj is shown in FIG. 3 as equation (2) or equation (3). The amount of heat Qj may be calculated using equation (2) or equation (3). In equation (2), Rcel represents the internal resistance of the battery at the current time (Tp). Also, in equation (3), OCV represents the open circuit voltage of the battery at the current time (Tp), and Vced represents the voltage of the battery at the current time (Tp).

[0027] In the case of equation (2), the calorific value Qj is the product of the square of the charging current Crt and the internal resistance Rcel of the battery. In the case of equation (3), the calorific value Qj is the product of the subtraction between the open circuit voltage OCV and the battery voltage Vced multiplied by the charging current Crt. In other words, the calorific value Qj is calculated based on the charging current Crt.

[0028] In step S3, the amount of heat dissipation Qout of the battery is calculated. The formula for calculating the amount of heat dissipation Qout is shown as equation (4) in FIG. 3. In equation (4), Ts_Tp indicates the surface temperature of the battery at the current time (Tp), and Rin_Tp corresponds to the temperature resistance Rin of the battery, which is the temperature resistance value at the current time (Tp). As can be seen from equation (4) in FIG. 3, the amount of heat dissipation Qout is calculated by dividing the temperature difference between the surface temperature Ts_Tp at the current time and the internal temperature Tin_To at the past time (To) by the temperature resistance Rin_Tp. In other words, the amount of heat dissipation Qout is calculated based on the temperature difference between the current surface temperature and the past internal temperature.

[0029] The entropy heat Qe, heat generation amount Qj, and heat dissipation amount Qout calculated in steps S1 to S3 are supplied to step S4. In step S4, the processor core uses these to calculate the internal temperature Tin of the battery at the current time. The equations for calculating the internal temperature Tin at the current time (Tp) are shown in FIG. 3 as equations (5) and (6). In equations (5) and (6), Hcp represents the heat capacity of the battery. Furthermore, Δt represents the time difference between the past time (To) and the current time (Tp), and ΔTin represents the amount of change in the internal temperature Tin that changes with the time difference Δt.

[0030] As can be seen from equation (5) in FIG. 3, the change in the internal temperature Tin during the time difference Δt is calculated by subtracting the heat dissipation amount Qout from the sum of the entropy heat Qe and the heat generation amount Qj and dividing the result by the heat capacity Hcp. Therefore, as shown in equation (6), the internal temperature Tin_Tp at the current time (Tp) can be calculated by multiplying the change ΔTin by the time difference Δt and adding the internal temperature Tin_To at the past time (To). This calculated internal temperature Tin_Tp is stored in memory and used as the internal temperature Tin_To in the next internal temperature estimation process. Furthermore, the calculated internal temperature Tin_Tp is used as the estimated internal temperature Tin at the current time (Tp) for charge control when charging the battery.

[0031] The internal temperature estimation process ends in step S5. Steps S1 to S5 are repeated to estimate the internal temperature Tin of the battery, which changes over time.

[0032] According to the battery internal temperature estimation process of the first embodiment, the internal temperature of the battery can be estimated only from the surface temperature of the battery, without using the ambient temperature of the battery. That is, according to the first embodiment, the internal temperature of the battery can be estimated without using the uncertain ambient temperature, and the estimated value of the internal temperature can be stabilized.

[0033] Furthermore, in the internal temperature estimation process according to the first embodiment, it is not necessary to perform processing related to the environmental temperature, which makes it possible to shorten the processing time. By shortening the processing time related to the internal temperature estimation process, it is possible to speed up the response to a sudden change in the state of the battery (for example, a sudden change in the surface temperature) when charging the battery.

[0034] (Embodiment 2) Next, a charging system that employs the internal temperature estimation process described in the first embodiment will be described with reference to the drawings.

[0035] Fig. 4 is a block diagram showing the configuration of a charging system according to a second embodiment. In Fig. 4, reference numeral 1 denotes the charging system. The charging system 1 includes a battery pack BTP and a charging device CHU that charges a battery BT in the battery pack BTP. The battery pack BTP is coupled to the charging device CHU by power supply lines VL(+), VL(-) and a signal line SL. The charging device CHU is coupled to, for example, a commercial power supply (AC 100V) 2.

[0036] When charging the battery BT, status information of the battery BT is supplied from the battery pack BTP to the charging device CHU via a signal line SL. The charging device CHU, for example, steps down the power supply voltage from the commercial power supply 2 and supplies the voltage and current to the power supply lines VL(+), VL(-) in accordance with the status information of the battery BT. The battery BT is charged by the voltage and current from the charging device CHU.

[0037] <Battery pack BTP configuration> The battery pack BTP includes a battery BT, a semiconductor device 3 for battery management, a charge / discharge transistor (charge / discharge FET) 4, a current sensor (current measurement resistor) 5, and a temperature sensor (battery temperature detection circuit) 6. The semiconductor device 3 for battery management, the charge / discharge transistor 4, and the current sensor 5 are mounted on a substrate Sub shown in Fig. 2. The temperature sensor 6 is provided on the surface of the battery BT.

[0038] 4, the battery BT is composed of n battery cells BTC1 to BTCn connected in series, although this is not a particular limitation. The positive electrode of the battery BT is connected to a power supply line VL(+) via a charge / discharge transistor 4, and the negative electrode is connected to a power supply line VL(-) via a current sensor 5. The positive and negative electrodes of each of the battery cells BTC1 to BTCn are connected to the semiconductor device 3. A temperature sensor 6 provided on the surface of the battery BT is also connected to the semiconductor device 3.

[0039] When charging the battery BT, the semiconductor device 3 controls the charge / discharge transistor 4 so that voltage and current are supplied from the charging device CHU to the battery BT via the power supply line VL(+). On the other hand, when the battery pack BTP is connected to an electronic device (not shown) and power is supplied from the battery pack BTP to the electronic device, the semiconductor device 3 controls the charge / discharge transistor 4 so that the voltage and current from the battery BT are output from the battery pack BTP.

[0040] When charging the battery BT, the current sensor 5 measures the charging current flowing through the power line VL(-) and supplies the measurement result to the semiconductor device 3. Although not particularly limited, the current sensor 5 is configured by a shunt resistor connected between the power line VL(-) and the negative electrode of the battery pack BTP. A voltage corresponding to the charging current flowing through the shunt resistor is supplied to the semiconductor device 3 as the value (measurement result) of the charging current.

[0041] The temperature sensor 6 supplies the measured surface temperature of the battery to the semiconductor device 3 .

[0042] <<Semiconductor device 3 for battery management>> The semiconductor device 3 includes multiple circuit blocks, but only the circuit blocks necessary for explanation are shown in Fig. 4. In Fig. 4, 20 is an analog circuit block (analog block) that is connected to the battery BT, the charge / discharge transistor 4, and the current sensor 5 and mainly performs analog processing. Also, 10 is a processor circuit block (hereinafter also referred to as a processor unit) that is connected to the analog block 20 and a signal line SL.

[0043] The analog block 20 includes a selection circuit 20_1, a current detection circuit 20_2, a current measurement circuit 20_3, a voltage / temperature measurement circuit 20_4, a data processing circuit 20_5, and a charge transistor control circuit (charge / discharge FET control circuit) 20_6.

[0044] The selection circuit 20_1 is supplied with voltage information from the battery BT and the battery cells BTC1 to BTCn and temperature information detected by the temperature sensor 6. The selection circuit 20_1 sequentially selects voltage information and temperature information from the supplied voltage information and temperature information and supplies the selected information to the voltage and temperature measurement circuit 20_4. The voltage and temperature measurement circuit 20_4 measures the voltages of the battery BT and the battery cells BTC from the supplied voltage information, and measures the surface temperature of the battery BT from the supplied temperature information. The voltages of the battery BT and the battery cells BTC1 to BTCn and the surface temperature of the battery measured by the voltage and temperature measurement circuit 20_4 are supplied to the data processing circuit 20_5.

[0045] The current detection circuit 20_2 is connected to the current sensor 5 and detects whether or not a charging current is flowing based on the measurement result from the current sensor 5. When a charging current is flowing, the current measurement circuit 20_3 measures the value of the flowing charging current. The value of the charging current measured by the current measurement circuit 20_3 is supplied to the data processing circuit 20_5.

[0046] The data processing circuit 20_5 notifies the charge / discharge transistor control circuit 20_6 whether to charge or discharge the battery BT. In accordance with this notification, the charge / discharge transistor control circuit 20_6 controls the charge / discharge transistor 4 as described above. The data processing circuit 20_5 also performs predetermined processing on the voltage value of the battery BT (including battery cells BTC1 to BTCn), the surface temperature of the battery BT, and the charge current value supplied thereto, and supplies the results to the processor unit 10.

[0047] The processor unit 10 includes a processor core (hereinafter also referred to as a control unit) 10_2, a communication circuit 10_3, and a memory (storage circuit) 10_1.

[0048] The processor core 10_2 performs the charging process including the internal temperature estimation process described in the first embodiment while using data stored in the memory 10_1 in accordance with a program not shown. The state information of the battery BT created by the execution of the charging process in the processor core 10_2 is supplied to the charging device CHU by the communication circuit 10_3 via the signal line SL.

[0049] Although not particularly limited, an instruction from the charging device CHU to the battery pack BTP is supplied to the communication circuit 10_3 via a signal line SL and then supplied to the processor core 10_2. In accordance with the supplied instruction, the processor core 10_2 controls, for example, the data processing circuit 20_5.

[0050] <Charging device configuration> The charging unit CHU includes a semiconductor device 7 for charge control that controls the charging of the battery, a charging transistor (charging FET) 8, a current sensor (current measurement resistor) 9, and an AC / DC conversion circuit (AC-DC conversion circuit) VADC.

[0051] The AC / DC conversion circuit VADC converts the AC voltage from the commercial power supply 2 into a DC voltage in accordance with an instruction from the semiconductor device 7, and outputs the converted DC voltage.

[0052] The charging transistor 8 is connected between the power supply line VL(+) and the AC / DC conversion circuit VADC, and supplies the DC voltage output from the AC / DC conversion circuit VADC to the power supply line VL(+) when charging the battery BT in accordance with instructions from the semiconductor device 7.

[0053] The current sensor 9 has a configuration similar to that of the current sensor 5, and is connected between the power supply line VL(-) and the AC / DC conversion circuit VADC. The current sensor 9 measures the current flowing through the power supply line VL(-) when the battery BT is being charged, and notifies the semiconductor device 7 of the measurement result.

[0054] Like the semiconductor device 3, the semiconductor device 7 is also composed of multiple circuit blocks, but only the circuit blocks necessary for explanation are shown in Fig. 4. The semiconductor device 7 includes a processor unit 30, an output voltage measurement circuit 31, a current detection circuit 32, a current measurement circuit 33, a power supply control circuit 34, and a charging transistor control circuit (charge FET control circuit) 35.

[0055] The current detection circuit 32 detects whether or not a charging current is flowing based on the measurement result from the current sensor 9. If the current detection circuit 32 detects that a charging current is flowing, the current measurement circuit 33 measures the charging current value based on the measurement result from the current sensor 9. The measured charging current value is supplied to the power supply control circuit 34.

[0056] The output voltage measuring circuit 31 measures the voltage between the power supply lines VL(+) and VL(−), that is, the output voltage of the charging unit CHU, and outputs the measured voltage value to the power supply control circuit .

[0057] The processor unit 30 includes a processor core (control unit) 30_2, a memory (storage circuit) 30_1, and a communication circuit 30_3. The processor core 30_2 performs a predetermined operation using the memory 30_1 and the communication circuit 30_3 in accordance with a program (not shown). For example, when charging the battery BT, the processor core causes the communication circuit 30_3 to receive state information of the battery BT supplied via a signal line SL. The processor core 30_2 sets a value of a charging current and the like for the power supply control circuit 34 in accordance with the state information of the battery BT received by the communication circuit 30_3.

[0058] The power supply control circuit 34 controls conversion in the AC / DC conversion circuit VADC based on the current value from the current measurement circuit 33, the voltage value from the output voltage measurement circuit 31, and a value set by the processor core 30_2. Furthermore, the power supply control circuit 34 uses a charging transistor control circuit 35 to control so that the output of the AC / DC conversion circuit VADC is supplied to the power supply line VL(+) via the charging transistor 8 when charging the battery BT.

[0059] <Overall operation of the charging system> Fig. 5 is a flowchart for explaining the overall operation of the charging system according to embodiment 2. The overall operation of charging system 1 according to embodiment 2 will be explained using Fig. 4 and Fig. 5. In charging system 1 according to embodiment 2, battery BT is charged by rapid constant current charging (FastCC), which charges with a constant charging current, and rapid constant voltage charging (FastCV), which charges with a constant voltage. That is, battery BT is initially charged by rapid constant current charging, then switched to rapid constant voltage charging, and is charged by rapid constant voltage charging.

[0060] Although the present specification will be described using examples employing rapid charging (rapid constant voltage charging and rapid constant current charging), the term "rapid" does not mean that the charging current and charging voltage are limited to a specific range. Therefore, various values ​​of charging current and charging voltage are applicable.

[0061] In step SC0, the charging system 1 starts operation. The next step SC1 is a step that is executed mainly in the semiconductor device 3 for battery management.

[0062] First, in step SC1_0, the voltage / temperature measuring circuit 20_4 and the current measuring circuit 20_3 measure the voltages of the battery BT and the battery cells BTC1 to BTCn, the charging current of the battery BT, and the surface temperature of the battery BT.

[0063] Next, based on the voltage, charging current and surface temperature of the battery BT measured in step SC1_0, in step SC1_1, the processor core 10_2 calculates the ideal capacity (Qmax) of the battery that can be removed when the battery BT is in an open circuit (OCV) state, the remaining battery capacity (RC) and the dischargeable capacity (FCC) of the battery.

[0064] In the next step SC1_2, the processor core 10_2 calculates the state of charge (SOC) of the battery BT using the ideal capacity (Qmax) calculated in step SC1_1, the remaining battery capacity (RC), the dischargeable capacity (FCC) of the battery, and the state of charge (SOC_Fin) at the discharge end point where actual discharge is possible. Examples of equations for calculating the state of charge SOC are the following equations (7) and (8). FCC=Qmax×((100-SOC_Fin) / 100)...Equation (7) SOC(%)=RC / FCC×100...Formula (8)

[0065] Following step SC1_2, step SC1_3 is executed. Step SC1_3 is composed of two steps, SFV and SFC, and in step SC1_3, the charging current, voltage, etc. in the case of fast charging are calculated by the processor core 10_2. That is, in step SFV, the voltage value, etc. in the case of fast constant voltage charging (FastCV) is calculated by the processor core 10_2, and in step SFC, the charging current value, etc. in the case of fast constant current charging (FastCC) is calculated by the processor core 10_2.

[0066] The values ​​of the fast constant voltage charging (FastCV) and the fast constant current charging (FastCC) calculated at step SC1_3 are supplied to the communication circuit 10_3 by the processor core 10_2 at step SC1_4 and set in the communication circuit 10_3.

[0067] In step SC1_4, the values ​​of fast constant voltage charging (FastCV) and fast constant current charging (FastCC) set in the communication circuit 10_3 are supplied as state information of the battery BT to the communication circuit 30_3 in the charging device CHU via the signal line SL, and the communication circuit 30_3 acquires the state information of the battery BT.

[0068] At step SC2, the processor unit 30 sets the state information of the battery BT acquired by the communication circuit 30_2 in the power supply control circuit .

[0069] The power supply control circuit 34 controls the AC / DC conversion circuit VADC and controls the charging transistor 8 by the charging transistor control circuit 35 so as to charge the battery BT in accordance with the set state information (such as the charging current value and voltage value of the battery BT).

[0070] When charging of the battery BT is completed, charging by the charging system 1 ends in step SC3.

[0071] The internal temperature estimation process described in the first embodiment is performed in step SC1_3, so next, step SC1_3 will be described with reference to the drawings.

[0072] <Rapid constant current charging and rapid constant voltage charging> FIG. 6 is a flowchart showing the operation of the charging system according to the second embodiment.

[0073] When charging the battery BT by rapid constant current charging and rapid constant voltage charging, a normal charging system monitors the voltage and charging current of the battery BT, and controls charging using the voltage and charging current determined by monitoring as parameters. In the charging system according to the second embodiment, as described in the first embodiment, the estimated internal temperature is also used to control charging. That is, in addition to the two parameters of the battery voltage and charging current, the estimated internal temperature is also used as a parameter to control charging.

[0074] In the second embodiment, the estimated internal temperature is added as a parameter in the control of the fast constant current charging (FastCC) (step SFC in FIG. 5). That is, the internal temperature estimation process described in the first embodiment is added to the process of the fast constant current charging.

[0075] In Fig. 6, SFC indicates a step (process) of rapid constant current charging (FastCC) corresponding to step SFC indicated by the same reference numeral in Fig. 5, and SFV indicates a step (process) of rapid constant voltage charging (FastCV) corresponding to step SFV indicated by the same reference numeral in Fig. 5. Although not particularly limited, steps SFC and SFV are executed by processor unit 10 provided in semiconductor device 3 shown in Fig. 4. In this case, processor unit 10 executes steps SFC and SFV in parallel.

[0076] First, step SFV of rapid constant voltage charging will be described. Step SFV starts with step SFV0. In the next step SFV1, the voltage value to be applied to the battery BT during rapid constant voltage charging is calculated. The voltage value FastCV_V calculated in step SFV1 is supplied to step SFC of rapid constant current charging. In addition, the voltage value calculated in step SFV1 is determined to be used for rapid constant voltage charging in step SFV2. Thereafter, step SFV ends in step SFV3.

[0077] <<Fast constant current charging process>> Next, step SFC of rapid constant current charging will be described. Step SFC is made up of steps SFC0 to SFC5. When step SFC starts at step SFC0, steps SFC1 and SFC4 start in parallel.

[0078] Step SFC1 is the same as the flowchart (steps S1 to S4) described in FIG. 1 according to the first embodiment, and therefore description thereof will be omitted. As described in the first embodiment, in step S4, the internal temperature of the battery at the current time is estimated based on the surface temperature of the battery BT and the internal temperature at the past time stored in the memory. In the second embodiment, the memory 10_1 shown in FIG. 4 is used as a memory for storing the internal temperature at the past time, etc.

[0079] In step SFC2, PID control is performed using the internal temperature of the battery BT at the current time calculated in step SFC1 and a preset internal temperature of the battery (hereinafter also referred to as a target temperature). In the PID control, a PID coefficient that reduces the temperature difference between the estimated internal temperature and the target temperature is calculated by the processor core 10_2. The target temperature is preset in, for example, the memory 10_1 (FIG. 4).

[0080] In step SFC3, the processor core 10_2 calculates a charging current FastCC_I as a result of PID control based on the PID coefficients calculated in step SFC2. An example of a formula used in the calculation in step SFC3 is the following formula (9). In formula (9), MaxFCC is the maximum current value during fast constant current charging. FastCC_I = PID coefficient * MaxFCC (9)

[0081] In step SFC4, the processor core 10_2 calculates the value of the charging current (constant-voltage charging current) FastCV_I during control of the rapid constant-voltage charging using the voltage value FastCV_V of the rapid constant-voltage charging calculated in step SFV1. The value of the charging current FastCV_I can be calculated, for example, by subtracting the current voltage (close voltage) of the battery BT from the voltage value FastCV_V and dividing the result by the internal resistance (internal impedance) of the battery pack BTP or the like.

[0082] In the charging system 1 according to the second embodiment, in step SFC5, the value of the charging current FastCC_I calculated in step SFC3 is compared with the value of the charging current FastCV_I calculated in step SFC4, the lower value of the charging current is selected, and the selected charging current is set as the one to charge the battery BT. That is, in step SFC5, the processor core 10_2 compares the charging current FastCC_I associated with the rapid constant current charging with the charging current FastCV_I associated with the rapid constant voltage charging, and selects the one with the smaller current value. The battery BT is charged based on this selected charging current.

[0083] Then, step SFC ends in step SFC6.

[0084] Steps SFC and SFV shown in FIG. 6 are repeatedly executed, and the charging current value set in step SFC5 is supplied to the charging unit CHU as state information of the battery BT.

[0085] <<New challenges arising from adding estimated internal temperature as a parameter>> As mentioned above, in a typical charging system, charging is controlled using the battery voltage and charging current as parameters. For example, in the region where fast constant current charging (Fast CC) is performed (hereinafter also referred to as CC region), the charging current is used as the main parameter, and in the region where fast constant voltage charging (Fast CV) is performed (hereinafter also referred to as CV region), the battery voltage is used as the main parameter, making it possible to distinguish between the CC region and the CV region and switch the charging control method.

[0086] 6 is adapted to such a normal charging system, steps SFC4 and SFC5 become unnecessary. In this case, the following new problem arises.

[0087] That is, in the CV region, the charging current is no longer limited by the estimated internal temperature, and there is a risk that the battery BT may be overcharged. On the other hand, if the battery BT is charged using the charging current FastCC_I calculated in step SFC3 in the entire region (including the CC and CV regions) without distinguishing between the CC region and the CV region, the temperature range cannot be fully utilized, the charging current is limited, the charging time of the battery BT is extended, and a loss of charging time may occur.

[0088] In the second embodiment, steps SFC and SFV are executed in both constant current rapid charging and constant voltage rapid charging. That is, both charging currents FastCC_I and FastCV_I are calculated in all ranges, and the value of the charging current for charging battery BT is determined by the smaller of the calculated charging currents FastCC_I and FastCV_I. Therefore, when charging current FastCC_I is a small value in the CV range, the charging current for charging battery BT is limited by the internal temperature, and overcharging of battery BT can be prevented.

[0089] Furthermore, when the value of the charging current FastCV_I is small, the battery BT can be charged with a charging current that is not limited by the internal temperature, so the battery BT can be charged with a charging current value that makes full use of the upper temperature limit, thereby maximizing charging efficiency.

[0090] That is, according to the second embodiment, even if the estimated internal temperature is added as a new parameter when performing charging control, it is possible to prevent the battery from being overcharged and to prevent the occurrence of charging time loss.

[0091] According to the charging system 1 of the second embodiment, rapid charging using rapid constant current charging and rapid constant voltage charging can be realized while maximizing charging efficiency, thereby reducing total loss. In addition, it is possible to prevent the battery BT from overheating or becoming too hot, thereby suppressing deterioration of the battery BT.

[0092] It is also conceivable to calculate the charging current FastCC_I using the surface temperature of the battery BT instead of the estimated internal temperature, but there is a time lag between the heat generated inside the battery BT and being transferred to the surface of the battery BT, which would result in poor responsiveness of the charging current FastCC_I. Also, if heat is suddenly generated inside the battery BT, there is a time lag, which would result in delayed detection. In the charging system 1 according to the second embodiment, the estimated internal temperature of the battery BT is used, which can improve responsiveness to heat generation.

[0093] <Charging characteristics> Next, the effects of the charging system 1 according to the second embodiment will be described in detail using a comparative example.

[0094] Figures 7 to 10 are characteristic diagrams showing the characteristics during charging in Comparative Examples 1 to 4, and Figure 11 is a characteristic diagram showing the characteristics of the charging system according to Embodiment 2. Figures 7 to 11 are drawn based on the results of simulations carried out by the present inventors.

[0095] 7 to 11, the horizontal axis represents time, the vertical axis on the left side of the drawings represents the charging current of the battery BT, and the vertical axis on the right side of the drawings represents the charging voltage and the temperature of the battery BT.

[0096] In the figure, each square surrounded by a line indicates the charge capacity, and when there are 400 squares, the battery is 100% charged, i.e., fully charged. The numbers written in the squares indicate the charge capacity charged up to that point. For example, in FIG. 7, the number "320" indicates that the charge capacity charged from time t0 to time t_CCV is equivalent to 320 squares. The charge capacity charged from time t_CCV to time t_CED is represented by the sum of the numbers written in the squares.

[0097] <<Comparative Example 1>> 7 shows the characteristics of a charging system according to Comparative Example 1. In Comparative Example 1, battery charging starts at time t0 and ends at time t_CED. Battery charging is performed in the order of constant current charging (CC) and constant voltage charging (CV). That is, around time t_CCV, constant current charging is switched to constant voltage charging.

[0098] In Fig. 7, the dashed line V_CH indicates the battery voltage, and the solid line I_CH indicates the charging current supplied to the battery. The dashed-dotted line Ts indicates the surface temperature of the battery. In Comparative Example 1, the maximum current value of the charging current I_CH is limited to 2 amperes (A), and the ambient temperature is set to 25 degrees. The two-dot-dotted line V_MX indicates the maximum charging voltage value of the battery.

[0099] As shown in FIG. 7, in Comparative Example 1, the surface temperature of the battery is kept low, but the time t_CED at which charging of the battery is completed is long at approximately 54 minutes, and the charging time required for charging is long.

[0100] <<Comparative Example 2>> FIG. 8 shows the characteristics of a charging system according to Comparative Example 2. Comparative Example 2 is similar to Comparative Example 1, with the difference being that the maximum current value of the charging current I_CH is limited to 3 amperes (A). In FIG. 8, the two-dot chain line T_LU indicates the upper limit of the charging temperature (upper charge temperature limit), and the two-dot chain line T_R indicates the charging restart temperature at which charging is restarted. In Comparative Example 2, control is performed so that charging stops when the battery surface temperature reaches the upper charge temperature limit T_LU, and charging resumes when the temperature drops below the charging restart temperature.

[0101] In Comparative Example 2, the charging current I_CH is high (3 amperes), so it is possible to increase the charging capacity in a short time. However, because the charging current I_CH is high, as shown in FIG. 8, the battery surface temperature Ts rises and reaches the charging temperature upper limit T_LU, causing charging to stop (the charging current I_CH decreases). Thereafter, charging resumes when the surface temperature Ts drops below the charging resumption temperature T_R. Therefore, in Comparative Example 2, there are many periods of time during which rapid constant current charging is not performed.

[0102] <<Comparative Example 3>> Fig. 9 shows the characteristics of a charging system according to Comparative Example 3. The charging system according to Comparative Example 3 is configured to estimate the internal temperature Tin of the battery from the ambient temperature of the battery, and to control charging (temperature control) based on the estimated internal temperature Tin. That is, rapid constant current charging and rapid constant voltage charging are not performed, and the value of the charging current I_CH is controlled based on the estimated internal temperature. In the example shown in Fig. 9, when the internal temperature Tin (estimated internal temperature) of the battery is low (42 degrees or lower), the charging current I_CH is set to a high current value (3 amperes), when the internal temperature Tin (estimated internal temperature) is low (42 degrees or lower), the charging current I_CH is set to a standard current value (2 amperes), and when the internal temperature is high (43 degrees to 44 degrees), the charging current I_CH is set to a low current value (1 ampere).

[0103] As shown in Figure 9, if the battery's internal temperature Tin is equal to or lower than the upper charge temperature limit T_LU, the value of the charge current I_CH changes according to the temperature. As charging progresses with the charge current I_CH, the battery voltage V_CH rises, and as shown in Figure 9, the voltage V_CH may exceed the maximum charge voltage V_MX. If the battery voltage V_CH exceeds the maximum charge voltage V_MX, the battery will be overcharged, and if the limit is exceeded, there is a risk of gas emission, fire, etc.

[0104] <<Comparative Example 4>> Fig. 10 shows the characteristics of a charging system according to Comparative Example 4. Comparative Example 4 is a combination of Comparative Examples 2 and 3. That is, at the start of charging, temperature control T_CNT is performed, which controls the charging current I_CH based on the internal temperature Tin, as described in Comparative Example 3. When the battery voltage V_CH reaches the battery internal temperature control prohibited region A_tci (time t_TED), charging is switched to constant current rapid charging and constant voltage rapid charging (rapid charging control CCV) as described in Comparative Example 2. Unlike Comparative Example 2, the maximum current of the charging current I_CH in the rapid charging control CCV is set to 2 amperes.

[0105] In the temperature control T_CNT, the value of the charging current I_CH changes according to the internal temperature Tin, and the battery is charged. In the fourth comparative example, even if the internal temperature Tin does not exceed the charging temperature upper limit T_LU, when the battery voltage V_CH reaches the battery internal temperature control prohibited region A_tci, the system switches to the rapid charge control CCV, which sets the maximum current to 2 amperes. Because the maximum current is 2 amperes, switching to the rapid charge control CCV causes the battery voltage V_CH to drop. Thereafter, at time t_CCV, the system switches from rapid constant current charging to rapid constant voltage charging, thereby preventing the battery voltage V_CH from exceeding the maximum charging voltage V_MX.

[0106] In Comparative Example 4, in the charging temperature control T_CNT, in order to set the battery internal temperature control prohibited region A_tci, the charging current I_CH is controlled so that the internal temperature range is narrower than the internal temperature range that should be allowed. In other words, it is necessary to secure a margin for switching from the charging temperature control T_CNT to the rapid charging control CCV, which extends the charging time until the end of charging.

[0107] <<Characteristic Example of Embodiment 2>> According to the charging system 1 of the second embodiment, the value of the charging current I_CH changes slightly according to the internal temperature Tin of the battery BT, as shown in FIG. 11 . That is, it is possible to eliminate the time when rapid constant current charging is not performed, as described in the second comparative example. Furthermore, since the internal temperature Tin is calculated based on the surface temperature Tp of the battery BT, it is possible to estimate the internal temperature Tin that has good tracking ability with respect to temperature changes of the battery BT. Furthermore, it is possible to improve the tracking ability of the charging current I_CH with respect to changes in the internal temperature Tin.

[0108] Furthermore, in the second embodiment, in both constant current rapid charging and constant voltage rapid charging, the charging current FastCC_I is calculated based on the estimated internal temperature Tin, and the charging current FastCV_I during constant voltage rapid charging is calculated. Of the calculated charging currents FastCC_I and FastCV_I, the current based on the smaller current value is used as the charging current I_CH for charging the battery BT, thereby preventing overcharging as described in the third comparative example. Furthermore, switching from constant current rapid charging to constant voltage rapid charging is possible without providing a margin as described in the fourth comparative example. As a result, the charging system 1 according to the second embodiment can shorten the charging time to approximately 43 minutes, as shown in FIG. 11 . Of course, the charging system 1 according to the second embodiment also has a shorter charging time than the first comparative example.

[0109] (Embodiment 3) In the third embodiment, a charge control method that is effective when the battery BT is configured by a plurality of battery cells BTC1 to BTCn as shown in FIG. 4 will be described.

[0110] Fig. 12 is a flowchart showing the operation of the charging system according to embodiment 3. Fig. 12 is similar to Fig. 6, so differences will be mainly described. The main differences between Fig. 12 and Fig. 6 are that in Fig. 12, steps SFC7 to SFC10 have been added to step SFC related to rapid constant current charging, and step SFC5 (Fig. 6) has been changed to step SFC11.

[0111] The battery cells BTC1 to BTCn that make up the battery BT may have different characteristics. If the characteristics differ, for example, when charging, the state of charge (for example, the voltage of the battery cell) will differ between the battery cells, causing a malfunction. Steps SFC7 to SFC10 are steps that are executed to equalize the state of charge between the battery cells.

[0112] In step SFC7, the maximum voltage Max_FastCV when a battery cell (for example, BTC1 in FIG. 4) is subjected to rapid constant voltage charging is compared with the voltage MaxV of the battery cell BTC1 at the current time. If the voltage MaxV at the current time is smaller than the maximum voltage MaX_FastCV (Y), step SFC9 is executed next. On the other hand, if the voltage MaxV at the current time is greater than or equal to the maximum voltage MaX_FastCV (N), step SFC8 is executed next.

[0113] In step SFC8, a predetermined current value (step value) is subtracted from the current charging current value. Meanwhile, in step SFC9, a predetermined current value (step value) is added to the current current value. Based on the charging current value calculated in step SFC8 or SFC9, the value of the charging current FastMV_I for control based on the battery cell voltage MaxV (MaxV control) is calculated in step SFC10.

[0114] In step SFC11, the charging current FastCC_I calculated in step SFC3, the charging current FastCV_I calculated in step SFC4, and the charging current FastMV_I calculated in step SFC10 are compared, and the charging current with the smallest value is selected. This selected charging current is set as the current for charging the battery BT.

[0115] In the third embodiment, when a battery is made up of a plurality of battery cells, it is possible to reduce the difference in voltage between the battery cells due to charging.

[0116] Furthermore, in step SFC11, the charging current with the smallest current value is set as the current for charging battery BT. Therefore, when charging current FastMV_I is smaller than charging currents FastCC_I and FastCV_I, battery BT is charged based on charging current FastMV_I. As a result, according to the third embodiment, as described in the second embodiment, it is possible to prevent overcharging of the battery and the occurrence of charging time loss, while reducing the effects of characteristic variations between battery cells.

[0117] <Additional Notes> This specification describes inventions other than those described in the claims. Representative inventions are listed below. (A) a battery pack including a battery and a semiconductor device coupled to the battery; a charging device coupled to the battery pack, the charging device charging the battery based on battery state information related to the battery supplied from the semiconductor device; Equipped with The semiconductor device includes: a control unit that receives the charging current of the battery, the voltage of the battery, and the surface temperature of the battery and estimates the internal temperature of the battery; a memory for storing the internal temperature estimated by the control unit; Equipped with The control unit calculating an entropy heat of the battery at a predetermined time using the charging current being supplied and the internal temperature at a time before the predetermined time that is stored in the memory; Calculating the amount of heat generated by the battery from the charging current being supplied; determining a temperature difference between the internal temperature at a time before the predetermined time stored in the memory and the surface temperature of the battery being supplied, and calculating the heat dissipation amount of the battery from the temperature difference; an internal temperature of the battery at the predetermined time is estimated using the calculated entropy heat, the heat generation amount, and the heat dissipation amount; Charging system. (A-1) In the charging system described in (A), The semiconductor device determines a charging current for charging the battery based on the estimated internal temperature, and supplies the determined charging current to the charging device as the battery state information. Charging system. (A-2) In the charging system described in (A-1), The battery pack further comprises: a temperature sensor installed on the surface of the battery; a shunt resistor connected between the battery and the charging device; Equipped with The temperature measured by the temperature sensor is supplied to the semiconductor device as a surface temperature of the battery, and the current flowing through the shunt resistor is supplied to the semiconductor device as a current of the battery. Charging system. (A-3) In the charging system described in (A-1), the semiconductor device calculates a constant-voltage charging current when the battery is charged at a constant voltage, compares the calculated constant-voltage charging current with a charging current determined based on the estimated internal temperature, and supplies the smaller charging current to the charging device as the battery state information; Charging system.

[0118] The present invention has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the invention. For example, although examples using rapid charging (rapid constant voltage charging and rapid constant current charging) have been described in this specification, the term "rapid" does not mean that the charging current and charging voltage are limited to specific ranges. [Explanation of symbols]

[0119] 1 Charging System 2 Commercial power supply 3, 7 Semiconductor Devices BT Battery BTC, BTC1~BTCn battery cells BTP Battery Pack CHU charging device S0~S5, SC0~SC3, SFC, SFV steps

Claims

1. A semiconductor device that controls charging of a battery, a control unit that receives the charging current of the battery, the voltage of the battery, and the surface temperature of the battery and estimates the internal temperature of the battery; a memory for storing the internal temperature estimated by the control unit; Equipped with The control unit Calculating the entropy heat of the battery at a predetermined time using the charging current being supplied and the internal temperature at a time before the predetermined time that is stored in the memory; Calculating the amount of heat generated by the battery from the charging current being supplied; determining a temperature difference between the internal temperature at a time before the predetermined time stored in the memory and the surface temperature of the battery being supplied, and calculating the heat dissipation amount of the battery from the temperature difference; using the calculated entropy heat, the heat generation amount, and the heat dissipation amount to estimate an internal temperature of the battery at the predetermined time; the control unit calculates a charging current for charging the battery based on the estimated internal temperature of the battery, calculates a constant-voltage charging current that flows through the battery when charging the battery at a constant voltage, and sets the charging current to either the charging current determined using the estimated internal temperature of the battery or the calculated constant-voltage charging current. Semiconductor device.

2. 2. The semiconductor device according to claim 1, the memory stores a plurality of entropies each corresponding to a state of charge of the battery; the control unit selects an entropy corresponding to the state of charge of the battery at the predetermined time from the plurality of entropies stored in the memory, and calculates the entropy heat of the battery using the selected entropy; Semiconductor device.

3. 3. The semiconductor device according to claim 2, the memory stores the internal resistance of the battery; The control unit calculates the amount of heat generated by the battery using the internal resistance. Semiconductor device.

4. 3. The semiconductor device according to claim 2, the memory stores the open voltage of the battery; The control unit calculates the heat generation amount of the battery using the open voltage. Semiconductor device.

5. 5. The semiconductor device according to claim 3, the memory stores the temperature resistance of the battery; The control unit calculates the amount of heat dissipation of the battery using the temperature resistance. Semiconductor device.

6. 2. The semiconductor device according to claim 1, a charging current for charging the battery is determined based on a temperature difference between a set target temperature and an internal temperature of the battery estimated by the control unit; Semiconductor device.

7. 7. The semiconductor device according to claim 6, a charging current for charging the battery is determined by PID control using the target temperature and the estimated internal temperature of the battery as inputs; Semiconductor device.

8. 2. The semiconductor device according to claim 1, the control unit compares the charging current determined using the estimated internal temperature of the battery with the calculated constant voltage charging current, and selects the charging current with a smaller value as the charging current for charging the battery. Semiconductor device.

9. 9. The semiconductor device according to claim 8, the battery is composed of a plurality of battery cells, The control unit calculates a charging current for charging the battery based on a maximum voltage of the battery cell; the control unit compares the charging current determined using the estimated internal temperature of the battery, the constant voltage charging current, and a charging current calculated based on a maximum voltage of the battery cell, and selects the smaller charging current as the charging current for charging the battery. Semiconductor device.

10. A charge control method for controlling charging of a battery, comprising: storing an internal temperature of the battery in a memory at a time prior to a predetermined time; calculating an entropy heat of the battery at the predetermined time using the current of the battery at the predetermined time and the internal temperature of the battery stored in the memory; calculating a heat generation amount of the battery using the current of the battery at the predetermined time; determining a temperature difference between the internal temperature of the battery stored in the memory and the surface temperature of the battery at the predetermined time, and calculating a heat dissipation amount of the battery from the determined temperature difference; an internal temperature of the battery is estimated using the calculated entropy heat, the heat generation amount, and the heat dissipation amount; calculating a charging current for charging the battery based on the estimated internal temperature of the battery; Calculating a constant voltage charging current flowing through the battery when charging the battery at a constant voltage; setting the charging current to either a charging current determined using the estimated internal temperature of the battery or the calculated constant voltage charging current; Charging control method.

11. The charge control method according to claim 10, determining a charging current for charging the battery based on the estimated internal temperature of the battery; Charging control method.

12. The charge control method according to claim 11, a charging current determined using the estimated internal temperature of the battery is compared with the calculated constant voltage charging current, and the charging current having a smaller value is selected as the charging current for charging the battery; Charging control method.

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