JP2014071100A - Charge control device of power storage element, power storage device, and charge control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate chargeable power in which a charging current of a power storage element does not exceed an upper limit current value.SOLUTION: A CPU 12 performs processing for determining whether a state of a secondary battery 5 is a current restriction state or a voltage restriction state at elapse of a reference time T from a time point when receiving an estimation request of a chargeable power from an ECU. When the CPU determines that the state of the secondary battery 5 is the voltage restriction state, the CPU 12 estimates, as the chargeable power, a power W1(=Vm×(Vm-EX)/R) when a terminal voltage of the secondary battery 5 reaches an upper limit voltage value Vm at the elapse of the reference time T from the time point when the estimation request is received. In addition, when the CPU determines that the state of the secondary battery 5 is the current restriction state, the CPU 12 estimates, as the chargeable power, a power W2(=(E+R×Im)×Im) when a current flowing to the secondary battery 5 reaches an upper limit current value Im when receiving the estimation request.

Description

  The present invention relates to a technique for estimating chargeable power of a storage element.

  The chargeable power is the maximum power that can be input to the power storage element. For example, in a hybrid vehicle, a monitoring device that monitors a secondary battery estimates the chargeable power of the secondary battery, and the hybrid control ECU is within a range that does not exceed the chargeable power when the hybrid vehicle decelerates. There is an apparatus that controls the storage element to be charged by regenerative energy obtained by the regenerative operation of the motor. Here, conventionally, the current-internal resistance characteristic after charging for a predetermined time measured in advance, an estimated value of change in open-circuit voltage that changes due to charging for a predetermined time, and the upper limit voltage value of the secondary battery are determined in advance. There is a technique for obtaining the maximum chargeable current value at which the terminal voltage of the secondary battery after the time charging is the upper limit voltage value and estimating the chargeable power from the upper limit voltage value and the maximum chargeable current value (Patent Document 1). .

JP 2007-147487 A

  By the way, when a power storage element such as a secondary battery is used, it is often necessary to consider not only the upper limit voltage value but also the upper limit current value for safety reasons. However, in the above prior art, only the upper limit voltage value is considered in estimating the chargeable power, and the upper limit current value is not considered. For this reason, in the said prior art, if it charges for a predetermined time with the estimated chargeable electric power, there exists a possibility that a charging current may exceed an upper limit electric current value within the predetermined time.

  The present specification discloses a technique for estimating rechargeable power in which a current flowing through a power storage element is less likely to exceed an upper limit current value.

  The rechargeable power estimation device disclosed in this specification includes a process execution unit, and the process execution unit includes a condition determination process for determining whether an execution condition for estimating the chargeable power is satisfied, and the execution condition. If it is determined to satisfy, the state of the storage element is a voltage limit state in which the value of the terminal voltage of the storage element reaches the upper limit voltage value before the value of the current flowing through the storage element reaches the upper limit current value, A state determination process for determining whether or not a current limit state in which a value of a current flowing through the power storage element reaches the upper limit current value before a value of a terminal voltage of the power storage element reaches the upper limit voltage value; Is determined to be in the voltage limit state, the storage element at the time when a reference time has elapsed from the time when the determination is made that the execution condition is determined to satisfy the internal resistance of the storage element, the upper limit voltage value, and the execution condition is satisfied. When the chargeable power of the power storage element is estimated from the open circuit voltage of the battery and it is determined that the state of the power storage element is the current limiting state, the internal resistance of the power storage element, the upper limit current value, and the execution And a power estimation process for estimating the chargeable power of the power storage element from the open circuit voltage of the power storage element after the determination and before the elapse of the reference time.

  In the rechargeable power estimation apparatus, the processing execution unit executes a terminal voltage estimation process for estimating a terminal voltage of the secondary battery when the value of the current flowing through the secondary battery is the upper limit current value In the state determination process, when the estimated value of the terminal voltage is less than or equal to the upper limit voltage value, the state of the storage element is determined to be the current limiting state, and the estimated value of the terminal voltage is You may judge that the state of the said electrical storage element is the said voltage restriction | limiting state when the said upper limit voltage value is exceeded.

  In the rechargeable power estimation device, the processing execution unit has a configuration that performs an open-circuit voltage estimation process for estimating an open-circuit voltage of the power storage element when the reference time has elapsed and before the reference time has elapsed, In the terminal voltage estimation process, the terminal voltage may be estimated based on the estimated value of the open circuit voltage, and in the power estimation process, the chargeable power may be estimated based on the estimated value of the open circuit voltage.

  Further, a power storage device including a power storage element and a chargeable power estimation device may be used.

  The technology disclosed in this specification is realized in various modes such as a failure diagnosis device, a failure diagnosis method, a computer program for realizing the functions of these devices or methods, and a recording medium on which the computer program is recorded. can do.

  According to the invention disclosed in this specification, it is possible to estimate rechargeable power in which the current flowing through the power storage element is less than the upper limit current value.

The block diagram which shows the structure of the battery pack which concerns on one Embodiment. A graph showing the relationship between the open-circuit voltage, upper limit voltage value, upper limit current value and internal resistance of the secondary battery Flow chart of rechargeable power estimation process for secondary battery A graph showing the relationship between the open-circuit voltage, upper limit voltage value, upper limit current value and internal resistance of the secondary battery in the voltage limit state A graph showing changes over time in the voltage, current, and rechargeable power of the secondary battery in the voltage limit state A graph showing the relationship between the open-circuit voltage, upper limit voltage value, upper limit current value and internal resistance of the secondary battery in the current limit state A graph showing changes over time in the voltage, current, and chargeable power of the secondary battery in the current limit state Graph showing current SOC value and rechargeable power

(Outline of the embodiment)
In the chargeable power estimation apparatus according to the present embodiment, when a power storage element is charged, it is determined whether the power storage element is in a voltage limited state or a current limited state. When the rechargeable power estimation device determines that it is in a voltage limit state, the rechargeable power estimation device obtains the open voltage of the storage element when the reference time has elapsed from the time when the execution is determined to satisfy the execution condition, and the open voltage, internal resistance, The chargeable power of the storage element is estimated from the voltage value. On the other hand, when the rechargeable power estimation device determines that the current is limited, the rechargeable power estimation device obtains the open voltage of the storage element before the reference time elapses from the execution determination time, and determines the open voltage, internal resistance, and upper limit current value. From this, the chargeable power of the power storage element is estimated. Thereby, regardless of whether the state of the power storage element is a current limited state or a voltage limited state, the chargeable power is estimated based on the open circuit voltage of the power storage element when the reference time has elapsed from the time of execution determination. It is possible to estimate the rechargeable power in which the current flowing through the power storage element is less likely to exceed the upper limit current value.

  According to this chargeable power estimation device, when the value of the current flowing through the secondary battery is an upper limit current value, the terminal voltage of the secondary battery is estimated, and when the estimated value is less than or equal to the upper limit voltage value, It is determined that the state of the storage element is a current limit state, and when the estimated value of the terminal voltage exceeds the upper limit voltage value, it is determined that the state of the storage element is a voltage limit state. Thereby, the state of the storage element can be determined by a relatively simple method of voltage comparison.

  According to the rechargeable power estimation device, when the reference time has elapsed and before the reference time has elapsed, the open-circuit voltage of the power storage element is estimated, and based on the estimated value of the open-circuit voltage, the terminal voltage is estimated, The chargeable power is estimated based on the estimated value of the open circuit voltage. Thereby, a common terminal voltage can be used in the condition determination process and the power estimation process.

(Electric configuration of battery pack)
A battery pack 1 according to an embodiment will be described with reference to FIGS. 1 to 8. Battery pack 1 is an example of a power storage device. The battery pack 1 is mounted on, for example, an electric vehicle or a hybrid vehicle (hereinafter simply referred to as an automobile), and supplies power to a power source that operates with electric energy under the control of an electronic control unit (hereinafter referred to as ECU) (not shown). The power is supplied or power is supplied from the power source.

  For example, when the driver of the automobile depresses the accelerator of the automobile, the battery pack 1 is discharged, and the ECU converts the electric energy into kinetic energy to drive the electric motor 11 (traveling motor). On the other hand, when the driver steps on the brake, the ECU operates the electric motor 11 as a generator to convert kinetic energy into electric energy. Thereby, the electric motor 11 can charge the secondary battery 5 by what is called a regenerative brake. Then, the ECU starts charging the battery pack 1 from the electric motor 11 with a chargeable power value, which will be described later, or with a power slightly smaller than the chargeable power value.

  As shown in FIG. 1, the battery pack 1 includes a battery module 2, a battery manager (hereinafter referred to as BM) 3 that manages the battery module 2, and a current sensor 4. The battery module 2 includes a secondary battery 5, a temperature sensor 6, a battery temperature measurement unit 7, and a battery voltage measurement unit 8. The battery temperature measuring unit 7 and the battery voltage measuring unit 8 are disposed on a common substrate, for example, and this circuit board is hereinafter referred to as a cell sensor (hereinafter referred to as CS) 9. BM3 and CS9 are examples of a process execution unit and a chargeable power estimation device.

  The secondary battery 5 is an example of a power storage element, for example, a lithium ion battery. The power storage element may be a capacitor in addition to the secondary battery 5. The secondary battery 5 and the current sensor 4 are connected in series with the electric motor 11 via the wiring 10. The temperature sensor 6 is disposed in contact with or near the secondary battery 5. The battery temperature measuring unit 7 measures the temperature D [° C.] of the secondary battery 5 using the temperature sensor 6 in a contact type or a non-contact type, and transmits the measurement result to the BM 3 via the communication line 16. The battery voltage measurement unit 8 measures the terminal voltage V [V] of the secondary battery 5 and transmits the measurement result to the BM 3 via the communication line 16.

  The BM 3 includes a central processing unit (hereinafter referred to as a CPU) 12, a memory 13, and a current measuring unit 14. The current measuring unit 14 uses the current sensor 4 to measure a current value I [A] of a charging current to the secondary battery 5 or a discharging current to the electric motor 11 (hereinafter referred to as charging / discharging current). A configuration including the BM 3, the current sensor 4, and the CS 9 is called a battery management system (hereinafter referred to as BMS) 15, and the BMS 15 is an example of a process execution unit and a chargeable power estimation device.

  The memory 13 stores various programs for controlling the operation of the CS 9. The CPU 12 controls each part such as executing a chargeable power estimation process described later according to a program read from the memory 13. The memory 13 stores an initial value of the internal resistance R of the secondary battery 5 and a resistance coefficient correspondence table. Here, the initial value of the internal resistance R is, for example, a value when the temperature of the secondary battery 5 is 25 ° C. and the SOC of the secondary battery 5 is 50%. The resistance coefficient is a coefficient with respect to the initial value of the internal resistance R of the secondary battery 5, and this resistance coefficient depends on the temperature of the secondary battery 5 and the state of charge (state of charge, also referred to as SOC). It changes depending on the situation. The resistance coefficient correspondence table stores each combination of the temperature and SOC of the secondary battery 5 and the resistance coefficient in association with each other. The memory 13 stores an SOC-OCV map indicating the relationship between the SOC and the open circuit voltage (hereinafter, also referred to as OCV). Further, the memory 13 stores an upper limit voltage value Vm and an upper limit current value Im of a secondary battery 5 described later.

(Current limit state and voltage limit state)
The secondary battery 5 enters a current limiting state or a voltage limiting state depending on the current value or temperature of the SOC. The current limit state is a state in which the current should be limited because the value of the current flowing through the secondary battery 5 reaches the upper limit current value Im before the terminal voltage value of the secondary battery 5 reaches the upper limit voltage value Vm. . The voltage limit state is a state where the terminal voltage should be limited because the value of the terminal voltage of the secondary battery 5 reaches the upper limit voltage value Vm before the value of the current flowing through the secondary battery 5 reaches the upper limit current value Im. is there.

  As shown in FIG. 2, the upper limit current value Im and the upper limit voltage value Vm are, for example, the upper limit values of the usable range P of the secondary battery 5, and the usable range P uses the secondary battery 5 safely, for example. Therefore, it is the range defined in the specification. The upper limit current value Im and the upper limit voltage value Vm may be an upper limit value of a control range determined in advance by the ECU. In the same figure, the lower limit voltage value Vs and the lower limit current value Is are shown as the lower limit values of the usable range P.

  A straight line F1 in FIG. 2 is a graph showing a change characteristic between the charge / discharge current and the terminal voltage when the secondary battery 5 is in the current limit state. The value of the open voltage of the secondary battery 5 is the first voltage value E1, and the internal resistance is the first resistance value R1. According to this straight line F1, the value of the current flowing through the secondary battery 5 reaches the upper limit current value Im before the value of the terminal voltage of the secondary battery 5 reaches the upper limit voltage value Vm. For this reason, it can be said that the secondary battery 5 in the state of the straight line F1 is in a current limiting state.

  A straight line F2 in the figure is a graph showing a change characteristic between the charge / discharge current and the terminal voltage when the secondary battery 5 is in the voltage limited state. The value of the open circuit voltage of the secondary battery 5 is the second voltage value E2 (> E1), and the internal resistance is the second resistance value R2 (> R1). According to this straight line F2, the value of the terminal voltage of the secondary battery 5 reaches the upper limit voltage value Vm before the value of the current flowing through the secondary battery 5 reaches the upper limit current value Im. For this reason, it can be said that the secondary battery 5 in the state of the straight line F2 is in a voltage limited state.

  As can be seen from the figure, whether the state of the secondary battery 5 is the current limiting state or the voltage limiting state is mainly determined by the open-circuit voltage and the internal resistance of the secondary battery 5. In particular, in an environment where the temperature change of the secondary battery 5 is small and the change in internal resistance is small, whether the state of the secondary battery 5 is the current limited state or the voltage limited state is mainly determined by the secondary battery. 5 is determined by the open circuit voltage. Note that the open circuit voltage of the secondary battery 5 has a correlation with the SOC, and the internal resistance has a correlation with the degree of deterioration of the secondary battery 5.

(Chargeable power estimation process)
The BMS 15 performs the chargeable power estimation process shown in FIG. 3 when power is supplied from, for example, the secondary battery 5. Specifically, the CPU 12 first determines whether or not there is a request for estimation of rechargeable power from the ECU (S11). Note that the chargeable power estimation request from the ECU is an example of an execution condition, and the process of S11 is an example of a condition determination process.

  When the CPU 12 determines that there is a request for estimation of rechargeable power from the ECU (S11: YES), as will be described later, from the time of the estimation request for rechargeable power from the ECU (hereinafter referred to as the time of estimation request). It is determined whether the state of the secondary battery 5 when the predetermined reference time T has elapsed is a current limited state or a voltage limited state (S18). As described above, whether the state of the secondary battery 5 is the current limiting state or the voltage limiting state is mainly determined by the internal resistance and the open circuit voltage of the secondary battery 5. Therefore, the CPU 12 estimates the current value of the internal resistance R of the secondary battery 5 and the current value of the open circuit voltage E.

  Specifically, the CPU 12 detects the current temperature of the secondary battery 5 from the measurement result of the battery temperature measurement unit 7 (S12), and estimates the current value of the SOC of the secondary battery 5 (S13). . Here, the CPU 12 estimates the current SOC value as follows. That is, the CPU 12 detects the open voltage of the secondary battery 5 from the measurement result of the battery voltage measurement unit 8 in a state where the automobile is stopped and the secondary battery 5 is not used for several hours, for example. Then, the CPU 12 refers to the SOC-OCV map stored in the memory 13 and obtains the SOC corresponding to the detected open circuit voltage as the initial value of the SOC. Thereafter, for example, when the driver of the automobile turns on the ignition key, the CPU 12 integrates the value of the charge / discharge current of the secondary battery 5 over time using the measurement result of the current measurement unit 14. Go.

  The CPU 12 sets a value obtained by adding the integrated value of the current SOC to the initial value of the SOC as the current value of the SOC. In addition, various known techniques can be used for estimating the SOC. The CPU 12 may execute the process of S12 and the process of S13 simultaneously, or may execute the process of S13 first and then execute the process of S12.

  Next, the CPU 12 estimates the current value of the internal resistance R of the secondary battery 5 based on the temperature value of the secondary battery 5 and the current value of the SOC (S14). First, the CPU 12 refers to the resistance coefficient correspondence table stored in the memory 13 and refers to the temperature value of the secondary battery 5 obtained in S12 and the resistance coefficient corresponding to the current value of the SOC obtained in S13. Is read. Then, the CPU 12 estimates the current value of the internal resistance R of the secondary battery 5 from the product of the read coefficient and the initial value of the internal resistance R stored in the memory 13. It can be said that estimating the current value of the internal resistance R of the secondary battery 5 is estimating the degree of deterioration of the internal resistance R of the secondary battery 5. In addition, in order to estimate the present value of the internal resistance R of the secondary battery 5, various known techniques can be used.

  Next, the CPU 12 refers to the SOC-OCV map, and estimates the current value of the open circuit voltage E of the secondary battery 5 corresponding to the current value of the SOC acquired in S13 (S15). The process of S15 is an example of an open circuit voltage estimation process. It can be said that estimating the current value of the open circuit voltage E of the secondary battery 5 is estimating the current value of the SOC of the secondary battery 5. Further, the CPU 12 may execute the process of S14 and the process of S15 at the same time, or may execute the process of S15 first and then execute the process of S14. In addition, in order to estimate the present value of the open circuit voltage E, various well-known techniques can be used.

  Next, the CPU 12 reads the upper limit voltage value Vm and the upper limit current value Im of the secondary battery 5 from the memory 13 (S16).

  Then, the CPU 12 estimates the value EX of the open circuit voltage E of the secondary battery 5 when the reference time T has elapsed (for example, after 10 seconds) from the estimation request (S17). The process of S17 is an example of an open circuit voltage estimation process. Specifically, the CPU 12 multiplies the upper limit current value Im of the secondary battery 5 by the reference time T to estimate the change amount ΔCC of the current integrated value from when the estimation request is made until when the reference time T has elapsed. The CPU 12 divides the obtained change amount ΔCC of the current integrated value by the total capacity Q of the secondary battery 5 to estimate the change amount of the SOC from the time when the estimation is requested to the time when the reference time T has elapsed. It can be said that estimating the change amount of the SOC is estimating the change amount of the open-circuit voltage E from the time when the estimation is requested to the time when the reference time T has elapsed.

  The CPU 12 adds the SOC change amount and the current SOC value obtained in S13 to estimate the SOC value when the reference time T has elapsed since the estimation request. Note that the SOC change amount may be stored in advance in the memory 13 instead of being calculated. Then, the CPU 12 refers to the SOC-OCV map, and determines the open circuit voltage value corresponding to the SOC value at the time when the reference time T has elapsed from the time of the estimation request, and the open circuit voltage at the time when the reference time T has elapsed from the time of the estimation request. Let E be the value EX. In addition, in order to estimate the value EX of the open circuit voltage E when the reference time T has elapsed from the time when the estimation is requested, various known techniques can be used.

  Next, the CPU 12 executes a state determination process for determining whether the state of the secondary battery 5 when the reference time T has elapsed from the time when the estimation is requested is a current limiting state or a voltage limiting state (S18). Specifically, the CPU 12 flows to the secondary battery 5 from the current value of the internal resistance R of the secondary battery 5 with the upper limit current value Im and S14 and the value EX of the open circuit voltage E when the reference time T has elapsed. The terminal voltage V (= EX + R × Im) when the current value is assumed to be the upper limit current value Im is estimated. This estimation process is an example of a terminal voltage calculation process.

When the CPU 12 determines that the terminal voltage V exceeds the upper limit voltage value Vm, the CPU 12 determines that the state of the secondary battery 5 is a voltage limited state (S18: NO), and determines the chargeable power W1 as the following formula 1 (S20), stored in the memory 13 (S21), and returns to S11. Note that the process of S20 is an example of a power estimation process.
<Formula 1>
W1 = Vm × (Vm−EX) / R

  In the example of FIG. 4, the straight line F3 is a graph showing a change characteristic between the charge / discharge current and the terminal voltage of the secondary battery 5 at the time of the estimation request. A straight line F4 is a graph showing a change characteristic between the charge / discharge current and the terminal voltage of the secondary battery 5 when the reference time T has elapsed since the estimation request. The symbol E3 in the figure is the open-circuit voltage value of the secondary battery 5 at the time of the estimation request, the symbol ΔE1 is the amount of change in the open-circuit voltage E from the time of the estimation request to the elapse of the reference time T, and the symbol E3 + ΔE1 is The open-circuit voltage value when the reference time T has elapsed from the time when the estimation is requested. The symbol R3 is a value of the internal resistance R of the secondary battery 5.

  At this time, since the terminal voltage V (= E3 + ΔE1 + R3 × Im) of the secondary battery 5 exceeds the upper limit voltage value Vm, the CPU 12 determines that the state of the secondary battery 5 is the voltage limit state (S18: NO). ). Then, when the reference time T has elapsed since the request for estimation, the CPU 12 uses the power W1 (= Vm × (Vm−EX) / R) when the terminal voltage of the secondary battery 5 is the upper limit voltage value Vm as the chargeable power. (Refer to the rectangular area indicated by random points in FIG. 4). Note that the estimation request is an example of execution determination.

  In order to make the explanation easy to understand, a case where the secondary battery 5 in the voltage limited state is charged with the constant power with the chargeable power W1 as shown in FIG. 5 will be described below. A symbol CT in the figure indicates an estimation request time. The upper part of the figure shows the change from the estimation request for the terminal voltage of the secondary battery 5, and the middle part shows the change from the estimation request for the current flowing through the secondary battery 5. In the lower part, chargeable power W1 is shown. This chargeable power W1 is a product value of the current value I (= (Vm−EX) / R) flowing through the secondary battery 5 when the reference time T has elapsed since the estimation request and the upper limit voltage value Vm.

  Here, in the voltage limit state, there is a particularly high possibility that the drivability of the driver of the automobile is impaired during the charging of the secondary battery 5 by the regenerative brake. As shown in FIG. 8 to be described later, in the voltage limited state, the SOC of the secondary battery 5 is relatively higher than in the current limited state, and there is a possibility that the battery will be fully charged relatively quickly during charging. For this reason, suppose that the CPU 12 is the product of the current value I (= (Vm−E) / R) flowing through the secondary battery 5 at the time of the estimation request and the upper limit voltage value Vm, that is, the open circuit voltage E at the time of the estimation request. When the ECU starts charging control for the secondary battery 5 using the chargeable power, the secondary battery 5 is fully charged in a relatively short time. Sometimes. Then, the ECU switches from the brake control using the regenerative brake to the brake control using the pad brake. As a result, the brake feel changes for the driver, and drivability is impaired.

  On the other hand, in this embodiment, the CPU 12 estimates the rechargeable power W1 based on the value EX of the open circuit voltage E when the reference time T has elapsed from the time when the estimation is requested, or the SOC value corresponding thereto, and the ECU Then, charging control to the secondary battery 5 is started with the chargeable power W1. Here, as described above, the voltage limit state is a state in which the terminal voltage should be limited. Further, the terminal voltage of the secondary battery 5 tends to increase with time during charging. For this reason, the ECU can continue the charging control of the secondary battery 5 without the terminal voltage V exceeding the upper limit voltage value Vm from the time when the estimation request is made until the reference time T elapses, and drivability may be impaired. The nature is low.

On the other hand, when the CPU 12 determines that the terminal voltage V is equal to or lower than the upper limit voltage value Vm, the CPU 12 determines that the state of the secondary battery 5 is the current limiting state (S18: YES), and sets the rechargeable power W2 to the next. 2 is calculated (S19), stored in the memory 13 (S21), and the process returns to S11. Note that the process of S19 is an example of a power estimation process.
<Formula 2>
W2 = (E + R × Im) × Im

  In the example of FIG. 6, the straight line F5 is a graph showing the change characteristics of the charge / discharge current and the terminal voltage of the secondary battery 5 at the time of the estimation request. A straight line F6 is a graph showing a change characteristic between the charge / discharge current and the terminal voltage of the secondary battery 5 when the reference time T has elapsed since the estimation request. The symbol E4 in the figure is the open circuit voltage value of the secondary battery 5 at the time of the estimation request, the symbol ΔE2 is the amount of change in the open circuit voltage E from the time of the estimation request to the time when the reference time T has elapsed, and the symbol E4 + ΔE2 is The open-circuit voltage value when the reference time T has elapsed from the time when the estimation is requested. The symbol R4 is the value of the internal resistance R of the secondary battery 5.

  At this time, since the terminal voltage V (= E4 + R4 × Im) of the secondary battery 5 is equal to or lower than the upper limit voltage value Vm, the CPU 12 determines that the state of the secondary battery 5 is the current limiting state (S18: YES). . At the time of the estimation request, the CPU 12 estimates the power W2 (= (E + R × Im) × Im) when the current flowing through the secondary battery 5 is the upper limit current value Im as the chargeable power (random in FIG. 6). (See the rectangular area indicated by the dots.)

  In order to make the explanation easy to understand, a case where the secondary battery 5 in the current limited state is charged with the constant power with the chargeable power W2 as shown in FIG. 7 will be described below. A symbol CT in the figure indicates an estimation request time. The upper part of the figure shows the change from the estimation request for the terminal voltage of the secondary battery 5, and the middle part shows the change from the estimation request for the current flowing through the secondary battery 5. In the lower part, chargeable powers W2 and W3 are shown. This chargeable power W2 is a product value of the terminal voltage value (E + R × Im) of the secondary battery 5 at the time of the estimation request and the upper limit current value Im. The rechargeable power W3 is a product value of the terminal voltage value (EX + R × Im) of the secondary battery 5 when the reference time T has elapsed from the time when the estimation request is made and the upper limit current value Im.

  Here, as described above, the current limit state is a state in which the current should be limited. Further, the current flowing through the secondary battery 5 tends to decrease with time during charging. Therefore, the CPU 12 estimates the chargeable power W3, that is, the chargeable power based on the value EX of the open circuit voltage E or the value of the SOC when the reference time T has elapsed since the estimation request, and the ECU When charging control to the secondary battery 5 is started with rechargeable power, the current flowing through the secondary battery 5 between the time when the estimation is requested and the time when the reference time T elapses, as shown in the middle part of FIG. (See the one-dot chain line in the middle of FIG. 7).

  On the other hand, in the present embodiment, the CPU 12 estimates the rechargeable power W2 based on the open circuit voltage E at the time of the estimation request or the SOC value corresponding thereto, and the ECU uses the rechargeable power W2 as a secondary. Control of charging the battery 5 is started. For this reason, the ECU can continue the charging control of the secondary battery 5 without the current flowing through the secondary battery 5 exceeding the upper limit current value Im from when the estimation request is made until the reference time T has elapsed (FIG. 7). (See the middle solid line). In the current limited state, since the SOC of the secondary battery 5 is relatively lower than that in the voltage limited state and the possibility of reaching full charge during charging is low, drivability is maintained even when charging is performed with the chargeable power W2. It is unlikely to be damaged.

(Effect of this embodiment)
According to the present embodiment, the CPU 12 performs a process of determining whether the state of the secondary battery 5 when the reference time T has elapsed from the time when the estimation is requested is a current limited state or a voltage limited state. When the CPU 12 determines that the state of the secondary battery 5 is the voltage limit state, the power W1 (=) when the terminal voltage of the secondary battery 5 is set to the upper limit voltage value Vm when the reference time elapses from the estimation request. Vm × (Vm−EX) / R) is estimated as chargeable power. Further, when the CPU 12 determines that the state of the secondary battery 5 is the current limiting state, the power W2 (= (E + R ×) when the current flowing through the secondary battery 5 is set to the upper limit current value Im at the time of the estimation request. Im) × Im) is estimated as chargeable power. Thereby, CPU12 can estimate the chargeable electric power in which the electric current which flows into the secondary battery 5 in a current limiting state does not exceed an upper limit electric current value.

<Other embodiments>
The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and includes, for example, the following various aspects.

  The CPU 12 may be configured to receive a result (temperature, SOC, internal resistance) estimated and measured by an external device such as an ECU without executing at least one of the processes of S12 to S15 in FIG. In this case, the CPU 12 does not need at least one of the battery temperature measurement unit 7, the battery voltage measurement unit 8, the current sensor 4, and the current measurement unit 14.

  In the above-described embodiment, when the CPU 12 determines that there is a request for estimation of rechargeable power from the ECU, the state of the secondary battery 5 when the predetermined reference time T has elapsed since the request for estimation is the current limit state. It was judged whether it was in a voltage-limited state. However, the present invention is not limited to this, and when the CPU 12 determines that charging of the secondary battery 5 has started, is the state of the secondary battery 5 when the predetermined reference time T has elapsed from the determination time determined to be a current limited state? It may be determined whether the voltage is limited. The CPU 12 may determine that charging of the secondary battery 5 has started on the condition that a charge start signal from the ECU or the like or an external signal such as a brake signal has been received. Further, the CPU 12 detects the direction of the current flowing through the wiring 10 based on the measurement result of the current sensor 4. Then, the CPU 12 starts charging the secondary battery 5 on the condition that the detected direction is switched from the discharge direction flowing out from the positive electrode of the secondary battery 5 to the charging direction flowing into the positive electrode of the secondary battery 5. You may judge.

  In the above embodiment, an estimation request for rechargeable power is given from the ECU as an example of execution conditions, and as an example of the condition determination process, the CPU 12 determines whether there is a request for estimation of rechargeable power from the ECU. Mentioned. However, the present invention is not limited to this, and the following may be used. That is, the CPU 12 executes the chargeable power estimation process shown in FIG. 3 and executes the chargeable power estimation process again after a predetermined time has elapsed since the chargeable power estimation process was executed. That is, the CPU 12 periodically executes the chargeable power estimation process every time a predetermined time period elapses. The execution condition may be that a predetermined time has elapsed. In this case, the condition determination process is to determine whether the CPU 12 has passed a predetermined time. It should be noted that the start of periodically executing the chargeable power estimation process by the CPU 12 may be when the power is supplied to the CPU 12 by, for example, an automobile driver turning on an ignition key.

  In the above embodiment, the CPU 12 estimates the internal resistance R of the secondary battery 5 from the resistance coefficient correspondence table and the initial value of the internal resistance. However, the present invention is not limited to this, and the CPU 12 first measures the voltage value of the secondary battery 5 by the battery voltage measurement unit 8 and measures the current value of the secondary battery 5 by the current measurement unit 14. Then, the CPU 12 may obtain a straight line based on a plurality of data of the detected voltage value and current value, and may estimate the internal resistance R of the secondary battery 5 from the slope of the obtained straight line.

  In the embodiment described above, the CPU 12 estimates the open circuit voltage E from the SOC-OCV map using the SOC obtained by adding the integrated SOC to the initial SOC as the estimated SOC. However, the present invention is not limited to this, and the CPU 12 first measures the voltage value of the secondary battery 5 by the battery voltage measurement unit 8 and measures the current value of the secondary battery 5 by the current measurement unit 14. And CPU12 calculates | requires a straight line based on the some data of the detected voltage value and electric current value. Next, the CPU 12 obtains the internal resistance R of the secondary battery 5 from the obtained straight line inclination. Finally, the CPU 12 may estimate the open circuit voltage E by adding the voltage value to the product of the current value multiplied by the internal resistance R.

  In the embodiment described above, the CPU 12 estimates the open circuit voltage E from the SOC-OCV map using the SOC obtained by adding the integrated SOC to the initial SOC as the estimated SOC. However, the present invention is not limited to this, and the CPU 12 first measures the terminal voltage value of the secondary battery 5 by the battery voltage measurement unit 8 and measures the value of the current flowing to the secondary battery 5 by the current measurement unit 14. Then, the CPU 12 obtains a straight line from the estimated current value of the internal resistance R and the measured voltage value / current value, and estimates the voltage when the current is zero on the straight line as the current value of the open circuit voltage E. Also good.

  In the above embodiment, the CPU 12 sets a value obtained by adding the integrated value of the current SOC to the initial value of the SOC as the current value of the SOC. However, the present invention is not limited to this, and the CPU 12 first measures the OCV of the secondary battery 5 by the battery voltage measurement unit 8. Then, the CPU 12 may refer to a predetermined SOC-OCV map and set the SOC corresponding to the measured OCV as the current SOC value.

  In the embodiment, the CPU 12 assumes that the terminal voltage V (= EX + R × Im) when the value of the current flowing through the secondary battery 5 is the upper limit current value Im, and the upper limit voltage value Vm read from the memory 13. By comparing these, it was determined whether the state of the secondary battery 5 was a current limited state or a voltage limited state. However, the determination is not limited to this. From FIG. 8, if the SOC at the time when the reference time T has elapsed from the time when the estimation is requested is less than the threshold (for example, 70% or less), the CPU 12 determines that the state of the secondary battery 5 is the current limiting state, and the chargeable power Is estimated. On the other hand, if the SOC at the time when the reference time T has elapsed since the request for estimation is greater than the threshold (for example, greater than 70%), the CPU 12 determines that the state of the secondary battery 5 is the voltage limit state, and the chargeable power Is estimated. The CPU 12 may determine whether the state of the secondary battery 5 is a current limited state or a voltage limited state as described above.

  In the embodiment, the CPU 12 assumes that the terminal voltage V (= EX + R × Im) when the value of the current flowing through the secondary battery 5 is the upper limit current value Im, and the upper limit voltage value Vm read from the memory 13. Was compared to determine whether the current limit state or the voltage limit state. However, the present invention is not limited to this, and the CPU 12 may make the determination by regarding the current value of the internal resistance R of the secondary battery 5 as constant when the usage environment of the battery pack 1 does not depend on temperature. In this case, the CPU 12 estimates only the current value of the open circuit voltage E and the value EX of the open circuit voltage E when the reference time T elapses from the time when the estimation request is made, and the state of the secondary battery 5 is the current limited state or the voltage limited state. Can be judged. Therefore, the CPU 12 may determine the state of the secondary battery 5 based on the SOC correlated with the open circuit voltage.

  In the embodiment, the CPU 12 assumes that the terminal voltage V (= EX + R × Im) when the value of the current flowing through the secondary battery 5 is the upper limit current value Im, and the upper limit voltage value Vm read from the memory 13. Was compared to determine whether the state of the secondary battery 5 was a current limited state or a voltage limited state. However, the present invention is not limited to this, and the CPU 12 determines the current value I (= (Vm−EX) / R) flowing through the secondary battery 5 when the terminal voltage value of the secondary battery 5 is assumed to be the upper limit voltage value Vm. By estimating and comparing with the upper limit current value Im read from the memory 13, it may be determined whether the state of the secondary battery 5 is a current limiting state or a voltage limiting state. Specifically, when the current value I is larger than the upper limit current value Im, the CPU 12 determines that the state of the secondary battery 5 is a current limiting state, and the current value I is less than or equal to the upper limit current value Im. In this case, the CPU 12 may determine that the state of the secondary battery 5 is a voltage limited state.

  In the above-described embodiment, the electric motor 11 is exemplified as a traveling motor. However, the present invention is not limited thereto, and the electric motor 11 may be a charging device that charges the secondary battery 5 from the outside of the vehicle, such as a charging stand.

  In the said embodiment, BM3 and CS9 were mentioned as an example of the chargeable electric power estimation apparatus. However, the present invention is not limited to this, and the BM 3 and CS 9 may be configured to execute various processes as a dischargeable power estimation apparatus. Specifically, the CPU 12 changes and executes part of the processing of the flow of FIG. In S11 of the figure, the CPU 12 determines whether or not there is a request for estimating dischargeable power. Then, in S <b> 16 of the figure, the CPU 12 reads the lower limit voltage value Vs of the secondary battery 5 from the memory 13 and reads the lower limit current value Is of the secondary battery 5. Then, in S18 of the figure, the CPU 12 determines whether or not the terminal voltage V exceeds the lower limit voltage value Vs. If the CPU 12 determines that the terminal voltage V exceeds the lower limit voltage value Vs, the CPU 12 determines that the secondary battery 5 is in a current limiting state, and estimates the dischargeable power as (E + R × Is) × Is in S19 of FIG. To do. Further, when the CPU 12 determines that the terminal voltage V is equal to or lower than the lower limit voltage value Vs, the CPU 12 determines that the secondary battery 5 is in the voltage limit state, and sets the dischargeable power to Vs × (Vs−EX) in S20 of FIG. ) / R.

  The dischargeable power estimation apparatus described above can be described as the following configuration. That is, a dischargeable power estimation device that estimates the dischargeable power of a storage element, comprising a process execution unit, wherein the process execution unit determines whether an execution condition for estimating the dischargeable power is satisfied And when the condition of the storage element is determined to satisfy the execution condition, the voltage at which the value of the terminal voltage of the storage element reaches the lower limit voltage value before the value of the current flowing through the storage element reaches the lower limit current value. State determination for determining whether the current state is a limited state or whether the current value flowing through the power storage element reaches the lower limit current value before the value of the terminal voltage of the power storage element reaches the lower limit voltage value When it is determined that the process and the state of the power storage element are in the voltage limit state, a reference time elapses from the time of execution determination that the internal resistance of the power storage element, the lower limit voltage value, and the execution condition are determined to be satisfied. When the dischargeable power of the power storage element is estimated from the open circuit voltage of the power storage element at the time, and it is determined that the state of the power storage element is the current limiting state, the internal resistance of the power storage element and the lower limit current Dischargeable power having a configuration for executing a value and a power estimation process for estimating the dischargeable power of the power storage element from the open circuit voltage of the power storage element after the execution determination time and before the reference time elapses Estimating device.

3: BM, 5: secondary battery, 9: CS, 12: CPU, 15: BMS

Claims (5)

A chargeable power estimation device for estimating chargeable power of a storage element,
A processing execution unit,
The process execution unit
A condition determination process for determining whether an execution condition for estimating the chargeable power is satisfied;
When it is determined that the execution condition is satisfied, the state of the power storage element is a voltage limit state in which the value of the terminal voltage of the power storage element reaches the upper limit voltage value before the value of the current flowing through the power storage element reaches the upper limit current value. Or a state determination process for determining whether the value of the current flowing through the storage element reaches the upper limit current value before the value of the terminal voltage of the storage element reaches the upper limit voltage value. ,
When it is determined that the state of the power storage element is the voltage limit state, the power storage at the time when a reference time has elapsed from the time of execution determination that the internal resistance of the power storage element, the upper limit voltage value, and the execution condition are determined to be satisfied When the chargeable power of the power storage element is estimated from the open circuit voltage of the element, and it is determined that the state of the power storage element is the current limiting state, the internal resistance of the power storage element, the upper limit current value, A chargeable power estimation apparatus having a configuration for executing a power estimation process for estimating chargeable power of the power storage element from an open voltage of the power storage element after the execution determination time and before the reference time elapses. The rechargeable power estimation device according to claim 1,
The process execution unit
A configuration for executing a terminal voltage estimation process for estimating a terminal voltage of the secondary battery when the value of the current flowing through the secondary battery is the upper limit current value;
In the state determination process, when the estimated value of the terminal voltage is less than or equal to the upper limit voltage value, the state of the storage element is determined to be the current limiting state, and the estimated value of the terminal voltage is the upper limit voltage value. The chargeable power estimation apparatus determines that the state of the power storage element is the voltage-limited state when the value exceeds. The rechargeable power estimation device according to claim 2,
The process execution unit
Having a configuration for performing an open-circuit voltage estimation process for estimating an open-circuit voltage of the power storage element before the reference time elapses when the reference time elapses;
In the terminal voltage estimation process, based on the estimated value of the open circuit voltage, the terminal voltage is estimated,
In the power estimation process, a chargeable power estimation device that estimates the chargeable power based on an estimated value of the open circuit voltage. A storage element;
A power storage device comprising: the chargeable power estimation device according to any one of claims 1 to 3. A chargeable power estimation method for estimating chargeable power of a storage element,
A condition determination step for determining whether or not an execution condition for estimating the chargeable power is satisfied;
When it is determined that the execution condition is satisfied, the state of the power storage element is a voltage limit state in which the value of the terminal voltage of the power storage element reaches the upper limit voltage value before the value of the current flowing through the power storage element reaches the upper limit current value. Or a state determination step of determining whether or not the value of the current flowing through the storage element reaches the upper limit current value before the value of the terminal voltage of the storage element reaches the upper limit voltage value. ,
When it is determined that the state of the power storage element is the voltage limit state, an open circuit voltage of the power storage element is obtained when a reference time has elapsed from a time when the execution is determined to satisfy the execution condition, and the open circuit voltage, the power storage element When the chargeable power of the power storage element is estimated from the internal resistance of the power supply and the upper limit voltage value and it is determined that the state of the power storage element is the current limit state, the power storage element is opened before the reference time has elapsed. A chargeable power estimation method including an estimation step of obtaining a voltage and estimating chargeable power of the power storage element from the open circuit voltage, the internal resistance of the power storage element, and the upper limit current value.

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