阅读说明：本技术 电池控制装置 (Battery control device ) 是由 赤津实幸 大川圭一朗 于 2019-09-25 设计创作，主要内容包括：存在具有微小的SOC的值被无视而产生信息丢失,并且不能正确进行SOC的运算的问题。因此,本发明的电池控制部(150)包括：基于电池的电压来计算充电率SOCv的SOCv运算部(151)；基于电池的电流值来计算充电率的变化量ΔSOCi的ΔSOCi运算部(152)；计算加权W的加权运算部(154)；基于SOCv、ΔSOCi、加权W来计算最终的SOC(SOCc)的SOCc运算部(153)。而且,使用判断阈值,将构成SOCc的运算式的多个项保持为较大值的组的项的总和SOCc-Big和较小值的组的项的总和SOCc-Small,并用于下一次的运算周期的SOCc计算。通过使用信息丢失导致的误差少的SOCc-Big和SOCc-Small,能够防止在反复SOCc运算时产生的信息丢失导致的误差的累积。(There is a problem that a value having a minute SOC is disregarded to cause information loss, and the SOC cannot be accurately calculated. Therefore, the battery control unit (150) of the present invention includes: an SOCv calculation unit (151) that calculates a charging rate SOCv based on the voltage of the battery; a delta SOCi calculation unit (152) for calculating the change amount delta SOCi of the charging rate on the basis of the current value of the battery; a weighting calculation unit (154) for calculating the weighting W; and an SOCc calculation unit (153) for calculating the final SOC (SOCc) on the basis of SOCv, Δ SOCi, and the weight W. Then, using the determination threshold, the plurality of terms constituting the operation expression of SOCc are held as the sum SOCc _ Big of the terms of the large-value group and the sum SOCc _ Small of the terms of the Small-value group, and used for SOCc calculation in the next operation cycle. By using SOCc _ Big and SOCc _ Small, which have Small errors due to information loss, it is possible to prevent accumulation of errors due to information loss occurring when SOCc operation is repeated.)

1. A battery control apparatus, comprising:

a first arithmetic unit that divides an arithmetic operation of a charging rate of a battery into a plurality of items and calculates each item;

a second arithmetic unit that divides the arithmetic results of the respective items calculated by the first arithmetic unit into a plurality of groups based on a predetermined threshold value and sums the arithmetic results for each group;

a storage unit that stores each group of operation results obtained by summing up the second operation unit in a previous operation cycle as previous values,

the first arithmetic unit calculates each item using a previous value of the group stored in the storage unit.

2. The battery control apparatus according to claim 1, characterized in that:

the first arithmetic unit divides the arithmetic operation of the state of charge of the battery into a plurality of terms not including addition and subtraction, and calculates each term.

3. The battery control apparatus according to claim 1 or 2, characterized in that:

a third arithmetic unit for adding the arithmetic results of the respective groups obtained by summing the arithmetic results of the second arithmetic unit,

the third arithmetic unit adds the arithmetic results of the respective groups and outputs the result as the current charging rate.

4. The battery control apparatus according to claim 1 or 2, characterized in that:

the calculation cycle includes the time when the battery control device finishes the action,

the storage section includes a nonvolatile memory that stores the previous value.

5. The battery control apparatus according to claim 1 or 2, characterized in that:

comprising any one or more of the following operations:

an SOCv calculation unit for calculating a charging rate of the battery using a voltage across the battery;

a Δ SOCi calculation unit that calculates a change amount of a charging rate of the battery obtained by integrating a current flowing through the battery from a previous calculation cycle; and

a weighting calculation unit for performing a weighting calculation using a weighting coefficient on the charging rate of the battery calculated by each of the SOCv calculation unit and the Δ SOCi calculation unit,

the first arithmetic unit calculates the items using values output from one or more of the SOCv arithmetic unit, the Δ SOCi arithmetic unit, and the weighting arithmetic unit.

6. The battery control apparatus according to claim 5, characterized in that:

the first arithmetic unit calculates each item using a value output from one or more of the SOCv arithmetic unit, the Δ SOCi arithmetic unit, and the weighting arithmetic unit, and a previous value of the group stored in the storage unit.

7. The battery control apparatus according to claim 1 or 2, characterized in that:

the second arithmetic unit divides the arithmetic result of each item calculated by the first arithmetic unit into a larger group including values equal to or greater than the threshold value and a smaller group including values smaller than the threshold value, and sums the arithmetic results for each group,

the storage unit stores the operation results of the 2 groups calculated by the second calculation unit in the previous operation cycle as previous values,

the first arithmetic unit calculates the items using previous values of 2 groups stored in the storage unit.

8. The battery control apparatus according to claim 1 or 2, characterized in that:

at least one of the first arithmetic unit and the second arithmetic unit includes a floating-point operation.

9. The battery control apparatus according to claim 1 or 2, characterized in that:

the second arithmetic unit divides the arithmetic result of each item calculated by the first arithmetic unit into a group consisting of values of larger bits than or equal to the bit and a group consisting of values of smaller bits than the bit based on the bit specified by the predetermined threshold value, and sums the arithmetic results for each group.

10. The battery control apparatus according to claim 1 or 2, characterized in that:

has a threshold value calculation unit for calculating the threshold value,

the threshold value calculation unit calculates the threshold value based on a previous value of the group.

11. The battery control apparatus according to claim 7, characterized in that:

has a threshold value calculation unit for calculating the threshold value,

the threshold value calculation unit calculates the threshold value based on a ratio of previous values of the group of the larger group and the smaller group.

12. The battery control apparatus according to claim 11, characterized in that:

the threshold value calculation unit sets the threshold value to be smaller when the previous value of the smaller group becomes larger.

Technical Field

The present invention relates to a battery control device.

Background

In order to make maximum use Of secondary batteries such as lithium ion batteries and nickel hydrogen batteries, it is necessary to estimate the State Of Charge (SOC) Of the secondary battery with high accuracy. The estimation of the SOC is generally a method of holding the previously estimated SOC and using the held SOC for calculation. Patent document 1 describes a method of holding a previous SOC obtained at a plurality of timings, selecting a plurality of the held SOCs, and using the selected SOCs for calculation of a current SOC.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-145349

Disclosure of Invention

Problems to be solved by the invention

However, when the current SOC is calculated using the previous SOC, if the magnitude of the value to be processed is significantly different between the amount of increase and decrease in the minute SOC and the amount of integration of the SOC up to this point, the minute SOC value is ignored, information is lost, and accurate calculation of the SOC is not performed.

Means for solving the problems

The battery control device of the present invention includes: a first arithmetic unit that divides an arithmetic operation of a charging rate of a battery into a plurality of items and calculates each item; a second arithmetic unit that divides the arithmetic results of the respective items calculated by the first arithmetic unit into a plurality of groups based on a predetermined threshold value and sums the arithmetic results for each group; and a storage unit configured to store, as previous values, respective operation results of groups to be summed by the second operation unit in a previous operation cycle, and the first operation unit is configured to operate the respective items using the previous values of the groups stored in the storage unit.

Effects of the invention

According to the present invention, the calculation error of the SOC due to the information loss can be suppressed.

Drawings

Fig. 1 is a block diagram showing the structure of a battery system.

Fig. 2 is a block diagram showing the configuration of the battery control unit.

Fig. 3 is a block diagram of the SOCc calculation unit in the first embodiment.

Fig. 4 is a flowchart showing the processing of the SOCcBig/Small arithmetic unit in the first embodiment.

Fig. 5 is a flowchart showing the processing of the SOCcBig/Small arithmetic unit in the second embodiment.

Fig. 6 is a block diagram of the SOCc calculation unit in the third embodiment.

Fig. 7 is a flowchart showing a process of the threshold value calculation unit in the third embodiment.

Detailed Description

[ first embodiment ]

A first embodiment will be described with reference to fig. 1 to 4.

Fig. 1 is a block diagram showing the structure of a battery system. The battery system 100 is a system for supplying power to an external supply target, such as an electric vehicle, a hybrid vehicle, an electric train, or an industrial device. Fig. 1 shows an example of supplying power to a motor generator 410 for running of a hybrid vehicle.

The battery system 100 is connected to the inverter 400 via the relays 300 and 310. The inverter 400 supplies electric power from the battery system 100 to the motor generator 410. The inverter 400 and the motor generator 410 are controlled by a motor/inverter control unit 420. Vehicle control unit 200 determines the distribution of driving force and the like based on battery information obtained by battery system 100, information from inverter 400 and motor generator 410, information from an engine not shown, and the like.

The battery system 100 includes: an assembled battery 110 composed of a plurality of single cells 111; a measurement unit 120 having a plurality of cell control units 121 that monitor the state of the cells 111; a current detection unit 130 that detects a current flowing through the battery pack 110; a voltage detection unit 140 that detects the total voltage of the battery pack 110; a battery control unit 150 that controls the battery pack 110; a storage portion 180 that stores information about battery characteristics of the battery pack 110, the battery cells 111, and the battery cell group 112.

The plurality of cells 111 constituting the battery pack 110 are grouped into a predetermined number of units. In the example shown in fig. 1, the plurality of battery cells 111 are grouped into 2 battery cell groups 112a, 112 b. The cell groups 112a, 112b are electrically connected in series.

The cell 111 is a rechargeable battery such as a lithium ion 2-time battery. As the cell 111, other than the above, a storage battery such as a nickel hydrogen battery, a lead battery, or an electric double layer capacitor, or a device having an electric storage function may be used. Here, a single cell is considered as the single cell 111, but the single cell 111 may be configured by a module structure in which a plurality of cells are connected in series or in parallel.

In the example shown in fig. 1, a configuration in which 2 battery cell groups 112a and 112b are connected in series is shown as the battery assembly 110, but the present invention is not limited thereto, and a predetermined number of battery cell groups may be connected in series or in parallel. In addition, the present invention may be configured by combining various numbers of the components in series or in parallel according to the application.

The measurement unit 120 monitors the state of each cell 111 constituting the battery assembly 110, and is provided with the same number of cell control units 121a, 121b corresponding to the plurality of cell assemblies 112a, 112 b. The cell control unit 121a is assigned to the cell group 112a, and the cell control unit 121b is assigned to the cell group 112 b. The cell controllers 121a and 121b operate by receiving power from the cell groups 112a and 112b allocated to them. The cell controllers 121a and 121b monitor the battery voltages and battery temperatures of the cell groups 112a and 112b allocated to the cell groups.

The value of the current flowing through the battery pack 110 transmitted from the current detection unit 130 and the total voltage value of the battery pack 110 transmitted from the voltage detection unit 140 are input to the battery control unit 150. The battery control unit 150 transmits and receives signals to and from the measurement unit 120 via the signal communication unit 160, and receives the battery voltage and the battery temperature of the battery cell 111 from the measurement unit 120, and further receives a diagnosis result of whether the battery cell 111 is overcharged or overdischarged, and an abnormality signal output when a communication failure occurs in the measurement unit 120. Battery control unit 150 performs processing such as estimation Of the State Of Charge (SOC) Of battery pack 110 based on the input information, and the processing result is transmitted to measurement unit 120 and vehicle control unit 200.

The battery control unit 150 performs numerical calculation processing Of state estimation calculation such as a state Of charge SOC and a state Of deterioration soh (states Of health) by 32-bit floating points. In the case of performing an operation with a fixed decimal point, the range of expressible values is narrow, and arithmetic overflow/arithmetic underflow or the like occurs, but if floating points are used, the range of expressible values is wide, and therefore the risk of occurrence of problems can be reduced. Although 32-bit floating points have a smaller number of significances than 64-bit floating points, the memory usage of 32-bit floating points is half that of 64-bit floating points, and therefore memory can be saved as compared with 64-bit floating points. In this embodiment, a 32-bit floating point is used, but the number of bits used for operation is not limited as long as the floating point is used, and any number of bits may be used.

Further, an insulating element 170 such as an optical coupler is provided in the signal communication section 160. As described above, the measurement unit 120 operates by receiving electric power from the battery pack 110, but the reference potential of the operating power supply of the battery control unit 150 and the measurement unit 120 is different because the battery control unit 150 uses a secondary battery for an on-vehicle auxiliary (for example, a 12V-type secondary battery) as a power supply. Therefore, the insulating member 170 is provided in the signal communication section 160. The insulating element 170 may be mounted on a circuit board constituting the measurement unit 120 or may be mounted on a circuit board constituting the battery control unit 150. In addition, the insulating member 170 can be omitted by the system configuration.

The cell control units 121a and 121b are connected in series in the order of the high to low potentials of the cell groups 112a and 112b to be monitored. The insulating element 170 is not provided between the output of the cell control unit 121a and the input of the cell control unit 121b, but this is because the cell control units 121a and 121b are configured to be able to communicate with each other even at different operation reference potentials. However, when electrical insulation is required for communication between the cell control unit 121a and the cell control unit 121b, the insulating element 170 needs to be provided.

The signal transmitted from the battery control unit 150 is input to the cell control unit 121a via the signal communication unit 160 provided with the insulating member 170. The output signal from the cell control unit 121b is transmitted to the input unit of the battery control unit 150 via the signal communication unit 160 provided with the insulating member 170. In this way, the battery control unit 150 and the cell control units 121a and 121b are connected in a ring shape by the signal communication unit 160. Such a connection and communication method is called a daisy chain connection, but may be called a bead connection, a daisy chain connection, or the like.

The storage unit 180 stores information such as internal resistance characteristics, capacity at full charge, polarization resistance characteristics, degradation characteristics, individual difference information, and a correspondence relationship (OCV-SOC map) between the open-circuit voltage OCV of the battery and the charging rate SOC of the battery, with respect to the battery pack 110, the unit cells 111, and the battery unit 112. In the example shown in fig. 1, the storage unit 180 is disposed outside the battery control unit 150 and the measurement unit 120, but the storage unit 180 may be disposed inside the battery control unit 150 or the measurement unit 120.

Fig. 2 is a block diagram showing the configuration of battery control unit 150. The battery control unit 150 includes: an SOCv calculation unit 151, a Δ SOCi calculation unit 152, an SOCc calculation unit 153, and a weighting calculation unit 154.

The voltage V of the battery cells 111 constituting the battery pack 110 (average voltage of each battery cell 111), the current I flowing through the battery pack 110, and the temperature T obtained in the battery pack 110 are input to the SOCv calculation unit 151. Here, the voltage V of the input single cell 111 is an average voltage of the voltages of the plurality of single cells 111 included in the battery pack 110. The SOCv calculation unit 151 calculates and outputs the charging rate SOCv of the battery based on the battery voltage V.

The current I flowing through the battery pack 110 is input to the Δ SOCi arithmetic unit 152. The Δ SOCi calculation unit 152 calculates an increase/decrease amount Δ SOCi of the current integration obtained by integrating the current flowing through the battery pack 110 over time from the previous calculation cycle. Δ SOCi is added to the state of charge SOC (SOCc described later) of the battery in the previous calculation cycle by SOCc calculation unit 153, and current integrated SOCi is calculated.

The current flowing through battery pack 110 and the temperature obtained in battery pack 110 are input to weighting unit 154. When SOCv can be obtained with high accuracy, the weighting calculation unit 154 calculates W as a large value and changes the weighting W so as to increase the specific gravity of the state of charge SOCv with respect to the state of charge SOCc. When the accuracy of the state of charge SOCv is not obtained, the weight W is reduced to increase the calculation weight of the state of charge SOCi.

In general, the SOC has a characteristic that the SOC estimation error is small when the current is stable, such as when the current flowing through the battery pack 110 is zero or the constant current continues for a certain time or longer, and is likely to become large when the current fluctuates sharply or the battery temperature is low. On the other hand, the SOC estimation error is small when the current is large and there is no sharp fluctuation, and is likely to become large when the current value is small and the measurement accuracy of the current detection unit 130 is likely to affect the SOC estimation error.

Therefore, the weighting calculation unit 154 and the SOCc calculation unit 153 adjust the influence on the final charging rate SOCc according to the weighting W with respect to the characteristics of the charging rate SOCv and the charging rate SOCi. This can improve the SOC estimation accuracy.

The SOCc calculation unit 153 calculates and outputs the final battery state of charge SOC (hereinafter SOCc) more reliably based on the state of charge SOCv as the output of the SOCv calculation unit 151, the amount of increase Δ SOCi in the state of charge from the previous calculation cycle as the output of the Δ SOCi calculation unit 152, and the weight W as the output of the weight calculation unit 154. The SOCc calculation unit 153 will be described later in detail with reference to fig. 3.

(basic formula for SOCv,. DELTA.SOCi, SOCc)

A basic expression of the calculation performed by the SOCc calculation unit 153 in the present embodiment will be described.

Equation (1) represents a basic equation relating the state of charge SOCc, the state of charge SOCv, the state of charge SOCi, and the weight W. If the weight W of the equation (1) is changed between 0 and 1, the ratio of SOCv and SOCi to the charging rate SOCc can be adjusted. If W changes in the direction of decreasing, SOCc becomes heavier than SOCi. Further, if W changes in the direction of increasing, SOCc becomes heavier than SOCv.

SOCc ═ W × SOCv + (1-W) × SOCi … formula (1)

The following expression (2) is an SOCi calculation expression in the present embodiment. The current-integrated SOC is obtained by adding the change amount Δ SOCi of the state of charge from the previous operation cycle to the SOC (hereinafter SOCc _ z) up to the previous operation cycle.

SOCi ═ Δ SOCi + SOCc _ z … formula (2)

The formula (3) is a modification of the formula (1) obtained by substituting the formula (2) into the formula (1). SOCv, Δ SOCi, and SOCc appearing in expression (3) correspond to the outputs of the SOCv arithmetic unit 151, Δ SOCi arithmetic unit 152, and SOCc arithmetic unit 153 in fig. 2, respectively.

SOCc (W × SOCv + (1-W) × (Δ SOCi + SOCc _ z) … formula (3)

As described above, in the SOCc calculation unit 153 of the present embodiment, the SOCc is calculated based on the basic expression (3). Since the basic formula (3) is another expression of the basic formula (1), it is known that the same processing as the formula (1) is performed. In the present embodiment, the cell controller 150 is configured by the SOCv calculator 151, Δ SOCi calculator 152, and SOCc calculator 153, but these do not need to be independent calculators, and may be performed by 1 calculator as long as the same processing as in the basic expression (3) is performed using SOCv and Δ SOCi. The present invention is not limited to 1 calculation unit, and may be performed in a plurality of calculation units. In the present embodiment, based on basic expression (3), SOCc calculation unit 153 modifies basic expression (3) as described below, derives 7 SOCc terms from SOCc, and calculates SOCc.

Note that although the flowcharts of the processing by the SOCc arithmetic unit 153 and the like will be described later, the programs shown in these flowcharts can be executed by a computer having a CPU, a memory, and the like. All or a portion of the processing may also be implemented by hard logic circuitry. Further, the program can be provided by being stored in advance in a storage medium of the battery control unit 150 or the storage unit 180. Alternatively, the program may be provided by being stored in a separate storage medium, or may be recorded and stored in the storage medium of the battery control unit 150 or the storage unit 180 through a network cable. The present invention may be supplied as a computer program product readable by a computer in various forms such as a data signal (carrier wave).

(information loss with respect to basic formula (3))

Here, the information loss of the basic expression (3) will be described. The expression (3) includes the operation of (1-W). In this case, when SOC calculation with a heavy SOCi is performed, the weight W may be a very small value. In this case, as a result of the subtraction of (1-W), an arithmetic error occurs due to information loss. This operation error becomes an error of SOCc in the current operation cycle. In the next operation cycle, the SOCc including the error of the previous operation cycle is input, and the SOCc of the next operation cycle is calculated, so the errors are accumulated. As described above, in the conventional technique, in the SOCc calculation of expression (3), by holding the SOCc of the previous calculation cycle and using it for the SOCc calculation of the current calculation cycle, the error due to the information loss caused by the calculation of (1-W) and the error of the SOCc (hereinafter, SOCc _ z) of the previous calculation cycle are accumulated.

(explanation of SOCc arithmetic part 153)

Fig. 3 is a block diagram of the SOCc calculation unit 153 according to the present embodiment. The SOCc calculation unit 153 includes: SOCc term calculation unit 500, SOCcBig/Small calculation unit 501, addition unit 502, previous value holding units 503 and 504, and determination threshold storage unit 505 receive SOCv, Δ SOCi, and weight W as input, and calculate SOCc as the final SOC. The previous value holding units 503 and 504 and the determination threshold value storage unit 505 may be provided in the storage unit 180, or the previous value holding units 503 and 504 and the determination threshold value storage unit 505 may be configured by a nonvolatile memory.

Here, SOCc _ Big and SOCc _ Small will be described. SOCc can be expressed by the sum of a plurality of operation terms. When a term having a large value among the plurality of operation terms is expressed as Big group, the sum thereof is expressed as SOCc _ Big, and a term having a Small value is expressed as Small group, the sum thereof is expressed as SOCc _ Small, the relational expression of expression (4) is obtained.

SOCc — Big + SOCc _ Small … formula (4)

SOCc _ Big and SOCc _ Small are the sums of terms of similar values, respectively. Since information loss occurs when a large value and a Small value are added and subtracted, there is a characteristic that there is no information loss error or little information loss error by performing the operations separately into SOCc _ Big and SOCc _ Small. With respect to SOCc (SOCc _ z) in the previous operation cycle, equation (5) can be obtained in the same manner as the relationship. SOCc _ Big _ z and SOCc _ Small _ z in equation (5) represent previous operation periods SOCc _ Big and SOCc _ Small, respectively.

SOCc _ z ═ SOCc _ Big _ z + SOCc _ Small _ z … formula (5)

By deriving the formula (5), the SOCc of the formula (3) is modified to obtain the formula (6). Equation (6) is an equation expressed by SOCc _ Big _ z and SOCc _ Small _ z having a Small information loss error, without using SOCc _ z containing an information loss error for the arithmetic term.

SOCc＝W×SOCv+(1-W)×(ΔSOCi+SOCc_Big_z+SOCc_Small_z)

… type (6)

Equation (6) can also be modified to equation (7). Expression (7) is expressed by 7 SOCc terms, and the individual calculation results of the SOCc terms do not include addition/subtraction that causes information loss.

SOCc ═ W × SOCv + Δ SOCi + SOCc _ Big _ z + SOCc _ Small _ z + (-W × Δ SOC i) + (-W × SOCc _ Big _ z) + (-W × SOCc _ Small _ z) … formula (7)

Here, the operation results of the 7 SOCc terms obtained by equation (7), i.e., (1) W × SOCv, (2) Δ SOCi, (3) SOCc _ Big _ z, (4) SOCc _ Small _ z, (5) (-W × Δ SOCi), (6) (-W × Δ SOC _ Big _ z), and (7) (-W × Δ SOC _ Small _ z) are only required to be assigned to a large-value term and a Small-value term based on the determination threshold SOCc _ th1, and SOCc _ Big and SOCc _ Small can be expressed by equations (8) and (9) below.

Sum … formula (8) of items having a large value not less than determination threshold value SOCc _ th1 among items SOCc _ Big (1) to SOCc (7)

Sum … formula (9) of Small items of SOCc _ th1 lower than determination threshold SOCc _ th in SOCc items (1) to (7)

In addition, SOCc _ Big _ z and SOCc _ Small _ z can be obtained in the next operation cycle by holding SOCc _ Big and SOCc _ Small obtained in the current operation cycle and referring to them in the next operation cycle.

SOCc _ Big _ z is SOCc _ Big … formula (10) of the previous operation cycle

SOCc _ Small _ z is SOCc _ Small … formula (11) of the previous operation cycle

The SOCc term calculator 500 in fig. 3 receives SOCv, Δ SOCi, weight W, SOCc _ Big _ z corresponding to expression (10), and SOCc _ Small _ z corresponding to expression (11) as inputs, and outputs calculation results of 7 SOCc terms obtained from expression (7), that is, (1) W × SOCv, (2) Δ SOCi, (3) SOCc _ Big _ z, (4) SOCc _ Small _ z, (5) (-W × Δ SOCi), (6) (-W × Δ SOC _ Big _ z), and (7) (-W × Δ SOC _ Small _ z).

The SOCcBig/Small operation unit 501 inputs the operation result of the SOCc term of (1) to (7) of the SOCc term calculation unit 500 and the output SOCc _ th1 of the determination threshold storage unit 505, and outputs SOCc _ Big and SOCc _ Small. As described above, the operation of at least one of the SOCc term calculation unit 500 and the SOCcBig/Small operation unit 501 includes a floating point operation.

Fig. 4 is a flowchart showing the processing of the SOCcBig/Small arithmetic unit 501. In step S100, the initial values are substituted into SOCc _ Big and SOCc _ Small. In step S101, one of the SOCc items that has not been subjected to the determination process is substituted into the determination target SOCc _ Jdg. In step S102, the determination target SOCc _ Jdg is compared with the determination threshold SOCc _ th1 to determine the size. That is, if SOCc _ Jdg > SOCc _ th1, the value of SOCc _ Jdg is added to SOCc _ Big in step S103. If SOCc _ Jdg is ≦ SOCc _ th1, the value of SOCc _ Jdg is added to SOCc _ Small in step S104. In step S105, it is determined whether there is an SOCc item for which no determination is made among the 7 SOCc items (1) to (7). If there is an SOCc item for which the judgment is not performed, the steps S101 to S105 are repeated for the item for which the judgment is not performed. In addition, when there is no item for which determination is not performed, the process is ended. In this way, the 7 SOCc items (1) to (7) are subjected to size determination, divided into 2 groups, and the SOCc items included in each of the 2 groups are summed up group by group, whereby SOCc _ Big and SOCc _ Small can be calculated.

The outputs SOCc _ Big and SOCc _ Small of SOCcBig/Small arithmetic unit 501 are held by previous value holding units 503 and 504, respectively. The held values are used as SOCc _ Big _ z and SOCc _ Small _ z in the next operation cycle. Here, SOCc _ Big _ z and SOCc _ Small _ z may use not only the held value calculated in the continuous cycle but also a value stored in the nonvolatile memory included in the storage unit 180 as the previous value. The previous value is stored in the nonvolatile memory when the vehicle is finished, and the previous value when the vehicle is finished is used as the SOC of the previous calculation cycle when the vehicle is started, so that the SOC calculation can be used when the normal SOC calculation cannot be performed when the vehicle is started. This is because, when the battery such as the battery pack 110 is not used, the reduction in SOC is small and the SOC is close to the calculation result of the SOC that can be obtained at the time of startup.

Returning to the description of fig. 3, the adder 502 calculates SOCc by using the sum of SOCc _ Big and SOCc _ Small corresponding to equation (4). The addition unit 502 is not limited to the example of using the sum of SOCc _ Big and SOCc _ Small, and may use the sum of the SOCc terms based on equation (7). In this way, the addition unit 502 capable of calculating SOCc limits the addition and subtraction method that causes information loss to 1 time.

In the present embodiment, SOCc _ Big and SOCc _ Small, which have a Small information loss, are calculated, and SOCc _ Big and SOCc _ Small are held and used as SOCc _ Big _ z and SOCc _ Small _ z in the next operation cycle. Thus, by using SOCc _ Big _ z and SOCc _ Small _ z having a Small error due to information loss, instead of using SOCc including an error due to information loss as the previous value of SOC used in the next calculation cycle, it is possible to prevent accumulation of errors due to information loss that occur when SOCc calculation is repeated. In addition, in the calculation of the final soc (SOCc), the sum of SOCc _ Big and SOCc _ Small, etc. can be used to reduce the calculation of the large value and the Small value, which are causes of the information loss, to 1 time of the minimum number of times.

[ second embodiment ]

Next, a second embodiment will be explained. The block diagram of the configuration of the battery system shown in fig. 1, the block diagram of the battery control unit shown in fig. 2, and the block diagram of the SOCc calculation unit shown in fig. 3 are the same in the second embodiment, and therefore, the description thereof is omitted.

Fig. 5 is a flowchart showing the processing of the SOCcBig/Small operation unit 501 in the second embodiment. The flowchart shown in fig. 4 of the first embodiment is different from the calculation method of SOC _ Big and SOC _ Small.

The determination threshold value (SOCc _ th1) of the determination threshold value storage unit 505 is used as a threshold value for determining the size of the SOCc term operation result in the first embodiment, but in the second embodiment, SOC _ th1 is used to allocate bits from the operation result of each SOCc term to a group of values obtained only with large bits and values obtained only with small bits. That is, a value obtained only at a large bit is treated as a value of the SOCc _ Big adder, and a value obtained only at a Small bit is treated as a value of the SOCc _ Small adder. For example, when SOCc _ th1 is 1, 1 or more bits and smaller bits are allocated to the addition targets SOCc _ Big and SOCc _ Small in SOCc _ th 1. For example, when the arithmetic result of the SOCc term is 12.345, the value of the SOCc _ Big adder is 12 and the value of the SOCc _ Small adder is 0.345. When SOCc _ th1 is equal to 0.1, the value of the SOCc _ Big adder is 12.3 and the value of the SOCc _ Small adder is 0.045.

In step S200 of fig. 5, the initial values are substituted into SOCc _ Big and SOCc _ Small. In step S201, the SOCc items not subjected to the determination process among the SOCc items are substituted into the determination target SOCc _ Jdg.

In step S202, the value of the SOCc _ Big addition unit described above is substituted into SOCc _ Jdg _ Big based on SOCc _ th 1.

In step S203, the value of the SOCc _ Small adder described above is calculated by using equation (12), and substituted into SOCc _ Jdg _ Small. This is expressed by the sum of the values of the SOCc _ Big adder and the SOCc _ Small adder using the results of the SOCc term operations.

SOCc _ Jdg _ Small ═ SOCc _ Jdg-SOCc _ Jdg _ Big … formula (12)

In step S204, the value SOCc _ Jdg _ Big of the SOCc _ Big addition unit is added to SOCc _ Big.

In step S205, the value SOCc _ Jdg _ Small of the SOCc _ Small addition unit is added to SOCc _ Small.

Step S206 determines whether or not there is an SOCc item for which no determination is made among the SOCc items (1) to (7). If there is an SOCc item for which no determination is made, steps S201 to S206 are repeated for the item for which no determination is made. In addition, when there is no item for which determination is not performed, the process is ended.

In the present embodiment, the output SOCc _ th1 of the determination threshold storage unit 505 is calculated by the bits of the value to be determined, using the SOCc _ Big adder derived only from the bits of the value equal to or greater than SOCc _ th1 and the SOCc _ Small adder derived only from the bits of the value smaller than SOCc _ th 1. The values of SOCc _ Big addition parts calculated from the SOCc terms are summed to calculate SOCc _ Big, and the values of SOCc _ Small addition parts calculated from the SOCc terms are summed to calculate SOCc _ Small.

In the present embodiment, too, by calculating SOCc _ Big and SOCc _ Small as in the first embodiment, accumulation of errors due to information loss occurring when the SOCc operation is repeated can be prevented by using SOCc _ Big _ z and SOCc _ Small _ z having Small errors due to information loss.

[ third embodiment ]

Next, a third embodiment will be explained. The block diagram of the configuration of the battery system shown in fig. 1 and the block diagram of the battery control unit shown in fig. 2 are the same in the third embodiment, and therefore, the description thereof is omitted. In the present embodiment, the configuration of the SOCc calculation unit 153' is different from that of the first embodiment.

Fig. 6 is a block diagram showing the SOCc calculation unit 153' in the third embodiment. The same parts as those of the SOCc calculation unit 153 shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the first embodiment, the determination threshold SOCc _ th1 is a fixed value, but in the present embodiment, the determination threshold SOCc _ th1 is dynamically changed.

The threshold value calculation unit 506 receives SOCc _ Big _ z, SOCc _ Small _ z, and the output SOCc _ th1_ z of the previous calculation cycle of the threshold value calculation unit 506, and outputs a determination threshold value SOCc _ th 1. The previous threshold value holding unit 507 holds the SOCc _ th1 of the current calculation cycle, and calculates the SOCc _ th1 (hereinafter, SOCc _ th1_ z) of the previous calculation cycle in the next calculation cycle.

Fig. 7 is a flowchart showing the processing of the threshold value calculation unit 506 in the third embodiment.

In step S300, from SOCc _ Big _ z and SOCc _ Small _ z, a ratio SOCc _ th1_ ratio is calculated by equation (13).

SOCc _ th1_ ratio ═ SOCc _ Small _ z/SOCc _ Big _ z … formula (13)

In step S301, the size determination of the ratio SOCc _ th1_ ratio and a predetermined determination threshold SOCc _ th2 is performed. If the ratio SOCc _ th1_ ratio is greater than the determination threshold SOCc _ th2, that is, if the following expression (14) is satisfied, the process of step S302 is performed. Determination threshold SOCc _ th2 is a determination threshold for determining SOCc _ Small _ z and SOCc _ Big _ z are very close to each other. In the case where the value of the SOCc term having a large value is included in SOCc _ Small _ z, the ratio SOCc _ th1_ ratio is larger than SOCc _ th 2.

SOCc _ th1_ ratio > SOCc _ th2 … formula (14)

In step S302, SOCc _ th1 in the present operation cycle is calculated by multiplying the gain value W1_ SOCc _ th1(W1_ SOCc _ th1<1) set to a value smaller than SOCc _ th1(SOCc _ th _1_ z) in the previous operation cycle by equation (15).

SOCc _ th1(SOCc _ th1_ zxw 1_ SOCc _ th1 … equation (15)

In step S301, if equation (14) is not satisfied, the process of step S304 is performed. Step S304 performs a size determination of the ratio SOCc _ th1_ ratio and a predetermined determination threshold SOCc _ th 3. That is, if equation (16) is satisfied, the process of step S303 is performed. Determination threshold SOCc _ th3 is a determination threshold for determining that SOCc _ Small _ z is a value very Small compared to SOCc _ Big _ z. In the case where the value of the SOCc term having a large value is not included at all in SOCc _ Small _ z, the ratio SOCc _ th1_ ratio is smaller than SOCc _ th 3.

SOCc _ th1_ ratio < SOCc _ th3 … formula (16)

In step S303, SOCc _ th1 in the present operation cycle is calculated by multiplying the gain value W2_ SOCc _ th1(W2_ SOCc _ th1>1) set to a value larger than SOCc _ th1(SOCc _ th _1_ z) in the previous operation cycle by equation (17).

SOCc _ th1 ═ SOCc _ th1_ zxw 2_ SOCc _ th1 … formula (17)

In step S304, if equation (16) does not hold, step S305 is performed. That is, step S305 is a process performed when expression (18) is satisfied.

SOCc _ th3 SOCc _ th1_ ratio SOCc _ th2 … equation (18)

In step S305, as shown in equation (19), SOCc _ th1 in the current calculation cycle is substituted into SOCc _ th1_ z as it is, and the value is not updated.

SOCc _ th1(SOCc _ th1_ z … equation (19)

In the present embodiment, in step S301, it is determined by the determination threshold SOCc _ th2 that the SOCc _ th1_ ratio is large, and an SOCc entry having a large value in SOC _ Small is detected. SOCc _ Small is the sum of SOCc terms having Small values, and the error due to information loss is Small, but when a SOCc term having a large value is present in the sum, the error becomes large. As a countermeasure, it is considered to exclude a large SOCc term from SOCc _ Small and shift to SOCc _ Big. When the determination threshold SOCc _ th2 determines that the SOCc _ th1_ ratio is large, the SOCc _ th1 of the current calculation cycle is reduced by using the gain value W1_ SOCc _ th 1. Thus, the large SOCc term included in SOCc _ Small in the current calculation cycle can be shifted to SOCc _ Big earlier than the fixed value SOCc _ th1 by the smaller determination threshold SOCc _ th 1.

However, when a large SOCc term is excluded from the sum object of SOCc _ Small, if a Small determination threshold SOCc _ th1 is maintained, the SOCc _ Big tends to include a Small SOCc term, and in this case, the error due to loss of information of SOCc _ Big may increase.

Therefore, when SOCc _ th1_ ratio is smaller than determination threshold SOCc _ th3, the processing of increasing determination threshold SOCc _ th1 is performed using gain value W2_ SOCc _ th 1.

When SOCc _ th1_ ratio is within the range between determination threshold SOCc _ th3 and determination threshold SOCc _ th2, it is determined that SOCc _ th1 is not required to be changed and the SOCc _ th1_ z is not updated.

In the present embodiment, the threshold value calculation unit 506 calculates SOCc _ th1 in the current calculation cycle using SOCc _ Big _ z, SOCc _ Small _ z and the determination threshold value SOCc _ th1(SOCc _ th1_ z) in the previous calculation cycle of the threshold value calculation unit itself, but may dynamically calculate the current calculation cycle using parameters related to the estimated state of another battery. Similarly to SOCc _ Big _ z and SOCc _ Small _ z, SOCc _ th1_ z uses not only a held value obtained by continuous cycle calculation but also a value stored in a nonvolatile memory included in the storage unit 180.

According to this embodiment, as in the first and second embodiments, SOCc _ Big and SOCc _ Small are calculated, and SOCc _ Big _ z and SOCc _ Small _ z having a Small error due to information loss are used, whereby accumulation of errors due to information loss occurring when the SOCc operation is repeated can be prevented. In the present embodiment, since the determination threshold SOCc _ th1 is dynamically changed and SOCc _ Big and SOCc _ Small are appropriately calculated, accumulation of errors due to information loss can be more reliably prevented when SOCc varies.

According to the above-described embodiment, the following operational effects are obtained.

(1) The battery control unit 150 includes: an SOCc term calculation unit 500 that divides the calculation of the battery charging rate into a plurality of terms and calculates each term; an SOCcBig/Small operation unit 501 that divides the operation results of the items operated by the SOCc item calculation unit 500 into a plurality of groups based on a predetermined threshold value and sums the operation results for each group; previous value holding units 503 and 504 respectively store the operation results of each group summed by the previous operation cycle by the SOCcBig/Small operation unit 501 as previous values, and the SOCc term calculation unit 500 calculates each term using the previous value of the group stored in the previous value holding units 503 and 504. This can suppress the calculation error of the SOC due to the loss of information.

(modification example)

The present invention can be implemented by modifying the first to third embodiments described above as follows.

(1) In the embodiment, the example of dividing the SOCc entry into 2 groups of SOCc _ Big and SOCc _ Small was described, but the SOCc entry may be divided into 3 or more groups based on a plurality of thresholds. Then, the items of the SOCc term are summed with groups divided into 3 or more, and the operation result of the summed groups is held as the previous value by group. Then, the held previous value is used for the next operation cycle.

The present invention is not limited to the above-described embodiments without impairing the features of the present invention, and other embodiments considered within the scope of the technical idea of the present invention are also included in the scope of the present invention. Further, the above embodiments and modifications may be combined.

Description of the reference numerals

100 cell system

110 battery pack

120 measuring part

130 current detecting part

140 voltage detection unit

150 battery control part

151 SOCv arithmetic unit

152 Delta SOCi arithmetic unit

153 SOCc arithmetic unit

154 weighting calculation unit

180 storage part

200 vehicle control unit

300. 310 relay

400 inverter

410 motor generator

500 SOCc term calculation unit

501 SOCcBig/Small arithmetic unit

502 addition unit

503. 504 previous value holding part

505 judgment threshold value storage unit

506 threshold value calculation unit

507 previous threshold holding unit.