JP7168336B2 - Secondary battery controller - Google Patents

Description

The present invention relates to a secondary battery control device.

2. Description of the Related Art Secondary battery systems such as power supply devices, distributed energy storage devices, and electric vehicles that use secondary batteries as power storage means are generally equipped with a battery control circuit that manages the state of the batteries. Typical examples of indices used by the battery control circuit to manage the state of the battery include state of charge (SOC), state of health (SOH), allowable current, allowable power, and the like. be. SOC indicates to what extent the battery has been charged (how much dischargeable charge remains in the battery), and SOH indicates how much the battery has deteriorated from its initial state. is. The allowable current is the maximum value of the current that can be charged and discharged by the battery, and the allowable power is the product of the allowable current and the battery voltage.

In recent years, the demand for higher output and longer life in secondary battery systems has been increasing more and more, and in order to achieve this, there is a demand for optimization of the SOC usage range used for charging and discharging batteries. A technique disclosed in Patent Document 1 below is known for optimizing the SOC use range. Patent Document 1 discloses a fuel cell that generates power by supplying both reactant gases to respective reactant gas flow paths, a power storage device that charges the power generated by the fuel cell and discharges the power, and the fuel cell. Alternatively, an auxiliary device driven by electric power of the power storage device, a voltage detection unit that detects the voltage of the power storage device, a deterioration determination unit that determines deterioration of the power storage device, and a power supply supplied from the power storage device to the auxiliary device a steady state determination unit that determines whether or not the electric power is in a steady state for a predetermined time, and the deterioration determination unit determines, when the steady state determination unit determines that the power is in a steady state for the predetermined time, the A fuel cell system is disclosed in which deterioration of the power storage device is determined based on the voltage of the power storage device detected by a voltage detection unit. According to the fuel cell system of Patent Document 1, since the deterioration determination is performed based on the voltage of the power storage device when the power storage device is in a steady state for a predetermined time, the deterioration determination of the power storage device can be accurately performed. be able to. By determining, for example, the output upper limit value of the power storage device or the SOC use range of the power storage device based on the deterioration determination result, the power storage device can be fully utilized from the time it is brand new.

JP 2009-231197 A

In the technique described in Patent Document 1, when power generation of the fuel cell is stopped and a constant current is supplied from the power storage device, it is determined that the power storage device is in a steady state, and the current value detected at this time and the Degradation determination is performed using the voltage value. Therefore, deterioration determination cannot be performed during operation of the secondary battery system, and therefore the SOC usage range cannot be optimized.

A secondary battery control device according to the present invention includes an SOC estimator that estimates the SOC (state of charge) of a secondary battery, and a voltage drop based on the OCV (open circuit voltage) and CCV (closed circuit voltage) of the secondary battery. A range of SOC used in charging and discharging the secondary battery based on a relationship between the voltage drop calculation unit to be calculated, the SOC estimated by the SOC estimation unit, and the voltage drop calculated by the voltage drop calculation unit or a use SOC determination unit that determines the central value.

According to the present invention, it is possible to optimize the SOC usage range during operation of the secondary battery system.

1 is a diagram showing a configuration of a battery system and its surroundings according to an embodiment of the present invention; FIG. It is a figure which shows the circuit structure of a cell control part. FIG. 4 is a block diagram showing details of processing performed by an assembled battery control unit in the first embodiment of the present invention; It is a circuit diagram which shows the equivalent circuit of a cell. FIG. 4 is a diagram showing an example of map information stored in a storage unit; FIG. 4 is a flowchart showing the flow of processing performed by an assembled battery control unit in the first embodiment of the present invention; FIG. 4 is a diagram showing an example of average values of voltage drops for each SOC range; FIG. 10 is a block diagram showing the details of processing performed by an assembled battery control unit in the second embodiment of the present invention; FIG. 9 is a flow chart showing the flow of processing performed by an assembled battery control unit in the second embodiment of the present invention; FIG. FIG. 11 is a block diagram showing details of processing performed by an assembled battery control unit in the third embodiment of the present invention; FIG. 11 is a flow chart showing the flow of processing performed by an assembled battery control unit in the third embodiment of the present invention; FIG. FIG. 12 is a block diagram showing the processing contents performed by the assembled battery control unit in the fourth embodiment of the present invention; FIG. 11 is a flow chart showing a flow of processing performed by an assembled battery control unit in the fourth embodiment of the present invention; FIG. FIG. 12 is a block diagram showing the processing contents performed by the assembled battery control unit in the fifth embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In each of the following embodiments, a case where the present invention is applied to an assembled battery control unit mounted in a battery system that constitutes a power source of a plug-in hybrid electric vehicle (PHEV) will be described as an example.

Further, in each of the following embodiments, lithium-ion batteries are employed and unit cells are connected in series to constitute an assembled battery. Alternatively, the unit cells connected in series may be connected in parallel to form an assembled battery.

<First Embodiment>
FIG. 1 is a diagram showing a configuration of a battery system 100 and its surroundings according to an embodiment of the present invention. Battery system 100 is connected to inverter 400 via relays 300a and 300b, and to charger 420 via relays 300c and 300d. The battery system 100 includes an assembled battery 110 , a cell management section 120 , a current detection section 130 , a voltage detection section 140 and an assembled battery control section 150 .

The assembled battery 110 is composed of a plurality of single cells 111 . The cell management unit 120 monitors the states of the cells 111 . Current detection unit 130 detects the current flowing through battery system 100 . Voltage detector 140 detects the total voltage of assembled battery 110 . The assembled battery control unit 150 detects the state of the assembled battery 110 and also manages the state.

The assembled battery control unit 150 functions as a secondary battery control device that detects the state of the assembled battery 110 , which is a secondary battery, and controls the assembled battery 110 in the battery system 100 . This assembled battery control unit 150 controls the battery voltage and temperature of each unit cell 111 transmitted by the unit cell management unit 120, the current value flowing through the battery system 100 transmitted by the current detection unit 130, and the assembled battery unit transmitted by the voltage detection unit 140. Receive 110 total voltage values. Based on the received information, the assembled battery control unit 150 detects the state of the assembled battery 110 and controls charging and discharging of the assembled battery 110 . The state detection result by the assembled battery control unit 150 is transmitted to the cell management unit 120 and the vehicle control unit 200 .

The assembled battery 110 is configured by electrically connecting in series a plurality of unit cells 111 capable of storing and discharging electrical energy (charging and discharging DC power). The unit cells 111 forming the assembled battery 110 are grouped into a predetermined number of units for managing and controlling states. The grouped unit cells 111 are electrically connected in series to form unit cell groups 112a and 112b. The number of cells 111 constituting the cell groups 112 may be the same in all the cell groups 112 , or the number of cells 111 may be different for each cell group 112 .

The unit cell management unit 120 monitors the state of the unit cells 111 that make up the assembled battery 110 . The cell management unit 120 includes a cell control unit 121 provided for each cell group 112 . In FIG. 1, cell controllers 121a and 121b are provided corresponding to the cell groups 112a and 112b. The cell control unit 121 monitors and controls the states of the cells 111 that make up the cell group 112 .

In the present embodiment, in order to simplify the description, four cells 111 are electrically connected in series to form cell groups 112a and 112b, and the cell groups 112a and 112b are further electrically connected in series. Thus, an assembled battery 110 including a total of eight cells 111 was obtained.

The assembled battery control unit 150 and the unit cell management unit 120 transmit and receive signals via an insulating element 170 typified by a photocoupler and a signal communication means 160 .

Communication means between the assembled battery control unit 150 and the cell control units 121a and 121b constituting the cell management unit 120 will be described. The unit cell controllers 121a and 121b are connected in series in descending order of the electric potential of the unit cell groups 112a and 112b that they monitor. A signal transmitted from the assembled battery control unit 150 to the cell management unit 120 is input to the cell control unit 121 a via the insulating element 170 and the signal communication means 160 . The output of the cell control unit 121a is input to the cell control unit 121b via the signal communication means 160, and the output of the lowest cell control unit 121b is input to the assembled battery control unit via the insulating element 170 and the signal communication means 160. 150. In Embodiment 1, the insulating element 170 is not interposed between the cell control unit 121a and the cell control unit 121b.

The assembled battery control unit 150 has a storage unit 151 . The storage unit 151 stores the internal resistance characteristics, the capacity at full charge, the polarization voltage, the deterioration characteristics, the individual difference information, the SOC, and the open circuit voltage (OCV: Open Circuit Voltage) of the assembled battery 110, the cell 111, and the cell group 112. Stores information such as the correspondence between Further, characteristic information of the cell management unit 120, the cell control unit 121, the assembled battery control unit 150, etc. can be stored in advance. Even if the operation of the battery system 100, the assembled battery control unit 150, etc. is stopped, the various information stored in the storage unit 151 is retained.

The assembled battery control unit 150 uses information received from the cell management unit 120, the current detection unit 130, the voltage detection unit 140, and the vehicle control unit 200 to determine the SOC, SOH, and allowable charge of one or more cells 111.・Performs calculations for detecting discharge current and power. Then, based on the calculation result, information is output to the cell management unit 120 and the vehicle control unit 200, and charge/discharge control of the assembled battery 110 is performed.

Vehicle control unit 200 uses information transmitted by assembled battery control unit 150 to control inverter 400 connected to battery system 100 via relays 300a and 300b. It also controls charger 420 connected to battery system 100 via relays 300c and 300d. While the vehicle is running, battery system 100 is connected to inverter 400 and uses energy stored in assembled battery 110 to drive motor generator 410 . When charging, battery system 100 is connected to charger 420 and charged by power supply from a household power source or a charging stand.

Charger 420 is used to charge assembled battery 110 using an external power source such as a home or a charging station. In the first embodiment, the charger 420 is configured to control charging voltage, charging current, etc., based on commands from the vehicle control unit 200, but control may be performed based on commands from the assembled battery control unit 150. . In addition, the charger 420 may be installed inside the vehicle or outside the vehicle depending on the configuration of the vehicle, the performance of the charger 420, the purpose of use, and the installation conditions of the external power source.

When the vehicle system equipped with the battery system 100 is started and runs, under the control of the vehicle control unit 200, the battery system 100 is connected to the inverter 400, and the energy stored in the assembled battery 110 is used to power the motor. Drive generator 410 . During regeneration, the assembled battery 110 is charged by the electric power generated by the motor generator 410 . When a vehicle equipped with the battery system 100 is connected to a household power source or an external power supply such as a charging station, the battery system 100 and the charger 420 are connected based on information transmitted by the vehicle control unit 200, and assembled. Battery 110 is charged until predetermined conditions are met. The energy stored in the assembled battery 110 by charging is used for the next running of the vehicle or for operating electrical components inside and outside the vehicle. Furthermore, if necessary, it may be discharged to an external power supply such as a household power supply.

FIG. 2 is a diagram showing the circuit configuration of the cell control unit 121. As shown in FIG. The cell control unit 121 includes a voltage detection circuit 122 , a control circuit 123 , a signal input/output circuit 124 and a temperature detection unit 125 . The voltage detection circuit 122 measures the voltage across the terminals of each cell 111 . The control circuit 123 receives measurement results from the voltage detection circuit 122 and the temperature detection section 125 and transmits them to the assembled battery control section 150 via the signal input/output circuit 124 . It should be noted that the circuit configuration for equalizing the voltage and SOC variations between the cells 111 that occur due to self-discharge, consumption current variations, etc., which is generally implemented in the cell control unit 121, is judged to be well known. and omitted the description.

A temperature detection unit 125 included in the cell control unit 121 in FIG. 2 has a function of measuring the temperature of the cell group 112 . Temperature detection unit 125 measures one temperature of unit cell group 112 as a whole, and treats that temperature as a temperature representative value of unit cells 111 constituting unit cell group 112 . The temperature measured by the temperature detection unit 125 is used for various calculations for detecting the state of the cell 111 , the cell group 112 , or the assembled battery 110 . Since FIG. 2 assumes this, one temperature detection unit 125 is provided in the cell control unit 121 . It is also possible to provide a temperature detection unit 125 for each unit cell 111 to measure the temperature of each unit cell 111 and execute various calculations based on the temperature of each unit cell 111. In this case, the number of temperature detection units 125 is increases, the configuration of the cell control unit 121 becomes complicated.

FIG. 2 simply shows the temperature detection unit 125 . Actually, a temperature sensor is installed on the temperature measurement object, and the installed temperature sensor outputs temperature information as a voltage. A result of the measurement is transmitted to the signal input/output circuit 124 via the control circuit 123 , and the signal input/output circuit 124 outputs the measurement result to the outside of the cell control section 121 . A function that implements this series of steps is implemented as a temperature detection unit 125 in the cell control unit 121, and a voltage detection circuit 122 can also be used to measure temperature information (voltage).

Various calculations performed by the assembled battery control unit 150 will be described below. The assembled battery control unit 150 is realized by a microcomputer or the like, and by executing various programs, can perform various processing and calculations as described below.

FIG. 3 is a block diagram showing details of processing performed by the assembled battery control unit 150 in the first embodiment of the present invention. The assembled battery control unit 150 has a storage unit 151 configured by a flash memory or the like, and has functional blocks of an SOC estimation unit 152 , a voltage drop calculation unit 153 and a use SOC determination unit 154 . These functional blocks each represent part of the processing and calculations performed by the battery pack control unit 150 .

The SOC estimating unit 152 determines the assembled battery 110 based on the voltage across the terminals of the single battery 111 detected by the voltage detecting circuit 122, the current I measured by the current detecting unit 130, and the temperature T measured by the temperature detecting unit 125. The SOC of each unit cell 111 is estimated. As the inter-terminal voltage of the cell 111, a voltage obtained by dividing the voltage of the assembled battery 110 measured by the voltage detection unit 140 by the number of the cells 111 in series may be used. As an example of processing contents for SOC estimation performed by the SOC estimating unit 152, SOC estimation processing based on voltage will be described below.

FIG. 4 is a circuit diagram showing an equivalent circuit of the cell 111. As shown in FIG. In FIG. 4, the cell 111 is composed of a voltage source 401 , a DC resistance 402 , a polarization resistance 403 and a capacitance component 404 . A polarization resistance 403 and a capacitance component 404 are connected in parallel, and the parallel connection pair, a voltage source 401 and a DC resistance 402 are connected in series.

Denoting the resistance value of the DC resistor 402 as Ro, and denoting the polarization voltage corresponding to the voltage of the parallel connection pair of the polarization resistor 403 and the capacitance component 404 as Vp, the voltage of the cell 111 when the current I is applied to the cell 111 is: A voltage between terminals (CCV: Closed Circuit Voltage) is represented by the following formula (1). In equation (1), OCV is the voltage across voltage source 401 . This OCV corresponds to the voltage across the terminals of the cell 111 when no charging/discharging current is flowing and the voltage is constant over time.
CCV = OCV + I x Ro + Vp (1)

The OCV is used to calculate the SOC (state of charge), but the CCV is measured while the cell 111 is being charged and discharged, making it impossible to directly measure the OCV. Therefore, the OCV is calculated by subtracting the IR drop and the polarization voltage Vp from the CCV using the following formula (2), which is a modified formula (1).
OCV = CCV - I x Ro - Vp (2)

The resistance value Ro of the DC resistor 402 and the polarization voltage Vp can be determined by characteristic information extracted from the cell 111 . The characteristic information of the cell 111 is stored in advance in the storage unit 151 as a value obtained experimentally by charging and discharging the cell 111 . A highly accurate OCV can be obtained by changing the characteristic information used for determining the resistance value Ro of the DC resistor 402 and the polarization voltage Vp according to the SOC, temperature, current, etc. of the cell 111. . Also, the voltage CCV between terminals is obtained by dividing the measurement result of the voltage detection unit 140 by the number of series cells 111 , and the current I is obtained from the measurement result of the current detection unit 130 .

In the above description, the OCV value is calculated from the CCV value measured during charging and discharging of the cell 111, and the SOC is estimated based on this value. You may estimate SOC using the value of OCV measured when it is not.

Next, as another example of processing contents for SOC estimation performed by the SOC estimation unit 152, SOC estimation processing based on current will be described. The SOC estimator 152 can also estimate the SOC of the cell 111 using the following equation (3). In equation (3), SOC0 represents the initial SOC value of the cell 111 before charging and discharging, and current I represents the measured value of the current detection unit 130 . Qmax represents the capacity of the cell 111 when it is fully charged, and is stored in the storage unit 151 in advance as a value obtained experimentally by charging and discharging the cell 111 or the assembled battery 110. .
SOCi = SOC0 + 100 x ∫Idt/Qmax (3)

SOC estimation section 152 may perform SOC detection using either equation (2) or equation (3). The SOC value obtained by SOC estimating section 152 is output from SOC estimating section 152 to storage section 151 at a predetermined cycle.

The voltage drop calculator 153 calculates the voltage drop, which is the difference between the OCV and the CCV, based on the inter-terminal voltage of the cell 111 detected by the voltage detection circuit 122 . The value of OCV at this time may be obtained from CCV using the above formula (2), or the voltage across the terminals of the cell 111 detected by the voltage detection circuit 122 when the cell 111 is not charged or discharged may be used. The voltage drop value calculated by voltage drop calculation unit 153 is output from voltage drop calculation unit 153 to storage unit 151 in a predetermined cycle synchronized with SOC estimation unit 152 .

Storage unit 151 stores map information representing the relationship between the SOC and the voltage drop based on the SOC value output from SOC estimation unit 152 and the voltage drop value output from voltage drop calculation unit 153. be. In this map information, a plurality of SOC values estimated at different timings by the SOC estimating unit 152 during charging and discharging of the assembled battery 110 and a plurality of voltage drops calculated by the voltage drop calculating unit 153 at synchronized timings. values are recorded in association with each other.

FIG. 5 is a diagram showing an example of map information stored in the storage unit 151. As shown in FIG. In the map information 501 shown in FIG. 5, a plurality of SOC values including SOC1 to SOC6 and a plurality of voltage drop values including ΔV1 to ΔV6 are recorded in association with each other. In addition to these SOC and voltage drop values, current values including I1 to I6 and temperatures including T1 to T6 are further associated and recorded. Current values I1 to I6 represent the values of the current I of the cell 111 respectively measured by the current detection unit 130 when SOC1 to SOC6 and ΔV1 to ΔV6 are acquired, and temperatures T1 to T6 represent the values of SOC1 to SOC6 and ΔV1 to ΔV6. shows the value of the temperature T of the unit cell 111 measured by the temperature detection unit 125 at the time of acquisition of . Note that the format of the map information stored in the storage unit 151 is not limited to that shown in FIG. 5 as long as the corresponding SOC, voltage drop, current, and temperature values can be referred to each other.

The used SOC determination unit 154 refers to the map information stored in the storage unit 151, and based on this, determines the range of SOC to be used in charging and discharging the assembled battery 110. FIG. By outputting information on the determined use SOC range to the cell management unit 120 and the vehicle control unit 200, the SOC range for charging and discharging the assembled battery 110 is limited.

Next, the details of the method for determining the used SOC range in the first embodiment of the present invention will be described. The use SOC determination unit 154 of the present embodiment determines the range of SOC to be used in charging and discharging the assembled battery 110 from the map information stored in the storage unit 151 by a method described below.

FIG. 6 is a flow chart showing the flow of processing performed by the assembled battery control unit 150 in the first embodiment of the present invention. The assembled battery control unit 150 of the present embodiment executes the process shown in the flowchart of FIG.

In step S<b>10 , the assembled battery control unit 150 acquires the voltage, current, and temperature of each unit cell 111 in the assembled battery 110 . Here, by receiving the measured values of the voltage and temperature of each cell 111 transmitted from the cell management unit 120 and the current value transmitted from the current detection unit 130 in the assembled battery control unit 150, these get the value. Alternatively, the total voltage value of the assembled battery 110 transmitted from the voltage detection unit 140 may be received, and the voltage of each unit cell 111 may be obtained based on this.

In step S<b>20 , the assembled battery control unit 150 uses the SOC estimation unit 152 to estimate the SOC. Here, based on the voltage, current, and temperature values obtained in step S10, the SOC of each cell 111 is estimated by the method described above.

In step S30, the battery pack controller 150 uses the voltage drop calculator 153 to calculate a voltage drop according to the difference between the OCV and the CCV. Here, as described above, the voltage drop can be calculated by obtaining the values of OCV and CCV from the voltage obtained in step S10 and calculating the difference between them. Alternatively, the voltage drop may be calculated by estimating the OCV value corresponding to the CCV based on the current and temperature values acquired in step S10 and calculating the difference between them. It should be noted that when the CCV value is obtained, the charging and discharging of the assembled battery 110 after the charging and discharging of the assembled battery 110 has been suspended for a certain period of time or longer, the charging and discharging after charging within a certain rate range, or the charging and discharging within a certain rate range. It is preferable to use the voltage obtained during the charging performed after discharging at .

In step S40, the assembled battery control unit 150 associates the SOC and voltage drop values obtained in steps S20 and S30 with the current and temperature values obtained in step S10, respectively, and stores the map information in the storage unit 151. to record. As a result, the map information illustrated in FIG. 5 is stored in the storage unit 151, and the map information is updated each time the SOC and voltage drop values are calculated.

In step S<b>50 , the battery pack control unit 150 determines whether a predetermined number or more of data are recorded in the map information stored in the storage unit 151 . By repeating the process of step S40 a predetermined number of times or more, if a predetermined number or more of data obtained by combining the corresponding SOC value and voltage drop value in the map information are recorded, affirmative determination is made in step S50. Proceed to step S60. On the other hand, if the number of times of processing in step S40 so far is insufficient and the predetermined number or more of data are not recorded in the map information, a negative decision is made in step S50, the process returns to step S10, and the above processes are repeated. . Thus, data recording to the map information is continued until sufficient data for use in determining the SOC range to be used is obtained.

In step S60, the assembled battery control unit 150 causes the use SOC determination unit 154 to refer to the map information stored in the storage unit 151, and classifies the SOC and voltage drop values in the map information for each current and temperature. . Here, using the current and temperature values recorded in the map information, each data obtained by combining the SOC and voltage drop values is classified into a plurality of groups. For example, when referring to the map information 501 illustrated in FIG. 5, it is determined to which of a plurality of preset groups the SOC and voltage drop values of each row belong from the current and temperature values of each row. By doing so, the map information 501 can be classified in the used SOC determination unit 154 .

In step S70, assembled battery control unit 150 causes usage SOC determination unit 154 to identify the group having the largest number of data among the plurality of groups classified in step S60, and determines the SOC and voltage drop values included in this group. to extract As a result, the values of the SOC and the voltage drop at the current I and the temperature T at which the battery pack 110 is most frequently charged and discharged can be obtained from the map information stored in the storage unit 151 .

In step S80, the assembled battery control unit 150 causes the use SOC determination unit 154 to calculate the average value of the voltage drop for each predetermined SOC range using the SOC and voltage drop values extracted in step S70. Here, for example, the minimum value that the SOC of each unit cell 111 can take is 10%, and the maximum value is 80%. Keep Then, one or more voltage drop values corresponding to each SOC range are obtained from the SOC and voltage drop values extracted in step S70, and the average value thereof is obtained. In this manner, the average voltage drop is calculated for each set SOC range.

FIG. 7 is a diagram showing an example of average values of voltage drops for each SOC range calculated by the above method. In the average value list 701 illustrated in FIG. 7, for example, the average voltage drop is 0.21V in the SOC range of 10% to 60%, and the average voltage drop is 0.20V in the SOC range of 11% to 61%. indicates that there is Similarly, the average value of the voltage drop is shown for each SOC range set in 1% increments from 30% to 80%.

Returning to the description of FIG. 6, in step S90, battery pack control unit 150 causes use SOC determination unit 154 to determine the average value of the voltage drop among the plurality of SOC ranges for which the average voltage drop was calculated in step S80. Identify the minimum SOC range. Then, this SOC range is determined as the use SOC range when charging and discharging the assembled battery 110 . For example, in the average value list 701 illustrated in FIG. 7, it is assumed that the average value of voltage drop is calculated to be 0.08 V in the SOC range of 25% to 75%, which is the minimum value. In this case, the used SOC determination unit 154 determines the used SOC range of each unit cell 111 in the assembled battery 110 to be 25% to 75%.

Using the SOC determination unit 154 performs the above-described processing, based on the relationship between the SOC estimated by the SOC estimation unit 152 and the voltage drop calculated by the voltage drop calculation unit 153, the SOC used in charging and discharging the assembled battery 110 is determined. A range of SOCs can be determined. After executing step S90, the assembled battery control unit 150 ends the processing shown in the flowchart of FIG.

According to the first embodiment of the present invention described above, the following effects are obtained.

(1) The assembled battery control unit 150 functions as a secondary battery control device that controls the assembled battery 110, which is a secondary battery. The assembled battery control unit 150 includes an SOC estimating unit 152 that estimates the SOC (state of charge) of the assembled battery 110, and a voltage A use SOC that determines the SOC range used in charging and discharging the assembled battery 110 based on the relationship between the drop calculation unit 153, the SOC estimated by the SOC estimation unit 152, and the voltage drop calculated by the voltage drop calculation unit 153. and a determination unit 154 . Since this is done, it is possible to optimize the SOC usage range during operation of the battery system 100, which is a secondary battery system.

(2) The battery pack control unit 150 further includes a storage unit 151 that stores map information 501 representing the relationship between SOC and voltage drop. As illustrated in FIG. 5, the map information 501 includes SOC1 to SOC6, which are SOC values estimated at different timings by the SOC estimation unit 152 during charging and discharging of the assembled battery 110, and SOC values synchronized with the SOC estimation unit 152. The voltage drop values ΔV1 to ΔV6 calculated by the voltage drop calculator 153 at the timing are recorded in association with each other. With this configuration, the SOC and the voltage drop values used by the used SOC determination unit 154 in determining the used SOC range can be held in an easy-to-reference format.

(3) Using SOC determination unit 154 calculates the average value of voltage drop for each predetermined SOC range based on map information 501 (step S80), and selects the SOC range with the smallest average value of the calculated voltage drop. The range of SOC used in charging and discharging the battery 110 is determined (step S90). Since this is done, the range of SOC used in charging and discharging the assembled battery 110 can be determined with an appropriate value.

(4) In the map information 501, the current and temperature of the assembled battery 110 are further associated and recorded. Based on this current and temperature, use SOC determination unit 154 classifies each data obtained by combining the corresponding SOC value and voltage drop value in map information 501 into a plurality of groups (step S60). Using the SOC value and the voltage drop value included in the group having the largest number of data among the groups (step S70), the SOC range used in charging and discharging the assembled battery 110 is determined (steps S80, S90). . Thus, the optimal SOC range for charging and discharging the assembled battery 110 can be determined from the SOC and voltage drop values at the current and temperature at which the assembled battery 110 is charged and discharged most frequently.

(5) When a predetermined number of data or more data obtained by combining the corresponding SOC value and voltage drop value are recorded in the map information 501 (step S50: Yes), the used SOC determining unit 154 performs steps S60 to S90. A process is executed to determine the SOC range to be used in charging and discharging the assembled battery 110 . By doing so, it is possible to prevent an SOC range with a large error from being calculated due to lack of data.

<Second embodiment>
Next, a second embodiment of the invention will be described. In this embodiment, instead of the assembled battery control unit 150 described in the first embodiment, an assembled battery control unit 150a described below is used to control charging and discharging of the assembled battery 110. FIG.

FIG. 8 is a block diagram showing details of processing performed by the assembled battery control unit 150a in the second embodiment of the present invention. Compared to the assembled battery control unit 150 of the first embodiment shown in FIG. 3, the assembled battery control unit 150a shown in FIG. The difference is that Except for this point, the configuration is similar to that of the assembled battery control unit 150 .

FIG. 9 is a flow chart showing the flow of processing performed by the assembled battery control unit 150a in the second embodiment of the present invention. The assembled battery control unit 150a of the present embodiment executes the process shown in the flowchart of FIG.

In steps S10 to S70, the assembled battery control unit 150a performs the same processes as described with reference to FIG. In step S80a, the assembled battery control unit 150a specifies the SOC value that minimizes the voltage drop value using the SOC and voltage drop values extracted in step S70 by the use SOC determining unit 154. Then, this SOC value is determined as the central SOC when the assembled battery 110 is charged and discharged.

The use SOC determination unit 154 of the assembled battery control unit 150a determines the assembled battery based on the relationship between the SOC estimated by the SOC estimation unit 152 and the voltage drop calculated by the voltage drop calculation unit 153 by the processing described above. It is possible to determine the center value of SOC used in charging and discharging of 110. After executing step S80a, the assembled battery control unit 150a ends the processing shown in the flowchart of FIG.

According to the second embodiment of the present invention described above, in addition to the effects (2), (4), and (5) described in the first embodiment, the following effects are obtained.

(6) The assembled battery control unit 150a functions as a secondary battery control device that controls the assembled battery 110, which is a secondary battery. The assembled battery control unit 150a includes an SOC estimation unit 152 that estimates the SOC (state of charge) of the assembled battery 110, and a voltage The center value of the SOC used in charging and discharging the assembled battery 110 is determined based on the relationship between the drop calculator 153, the SOC estimated by the SOC estimator 152, and the voltage drop calculated by the voltage drop calculator 153. and an SOC determination unit 154 . Since this is done, the SOC use range can be optimized during operation of the battery system 100, which is a secondary battery system, as in the first embodiment.

(7) Use SOC determination unit 154 identifies the SOC value that minimizes the voltage drop based on map information 501, and uses the identified SOC value as the central value of the SOC used in charging and discharging assembled battery 110. Determine (step S80a). Since this is done, the center value of the SOC used in charging and discharging the assembled battery 110 can be determined as an appropriate value.

<Third Embodiment>
Next, a third embodiment of the invention will be described. In this embodiment, instead of the assembled battery control units 150 and 150a described in the first and second embodiments, an assembled battery control unit 150b described below is used to control charging and discharging of the assembled battery 110. explain.

FIG. 10 is a block diagram showing details of processing performed by the assembled battery control unit 150b in the third embodiment of the present invention. Compared to the assembled battery control unit 150 of the first embodiment shown in FIG. 3, the assembled battery control unit 150b of FIG. It differs in that it further has a portion 155 . Except for this point, the configuration is similar to that of the assembled battery control unit 150 .

The storage control unit 155 stores the SOC value output from the SOC estimation unit 152, the voltage drop value output from the voltage drop calculation unit 153, the current I measured by the current detection unit 130, the temperature detection unit 125 The temperature T measured by is input. The storage control unit 155 controls updating of the map information stored in the storage unit 151 based on these pieces of information. Specifically, it is determined whether or not the current I and the temperature T respectively satisfy predetermined conditions, and only when it is determined that both conditions are met, the SOC and voltage drop values are recorded in the map information and updated. do. When at least one of the current I and the temperature T does not satisfy the conditions, the SOC and voltage drop values obtained by the SOC estimator 152 and the voltage drop calculator 153 are discarded without being recorded in the map information. . Therefore, the SOC and voltage drop values at this time are not used when use SOC determination unit 154 determines the use SOC range.

FIG. 11 is a flow chart showing the flow of processing performed by the assembled battery control unit 150b in the third embodiment of the present invention. The assembled battery control unit 150b of the present embodiment executes the process shown in the flowchart of FIG. 11 at predetermined processing intervals, for example, during charging and discharging of the assembled battery 110.

In step S10, the assembled battery control unit 150b acquires the voltage, current, and temperature of each unit cell 111 in the assembled battery 110 in the same manner as described with reference to FIG. In step S11b, the battery pack control unit 150b uses the memory control unit 155 to determine whether or not the current obtained in step S10 is within a predetermined current rate range. As a result, if the value of the acquired current I is within a predetermined current rate range, for example, within the range of 5C or more and 5.2C or less, the process proceeds to step S12b. Otherwise, the process returns to step S10 and waits until the next acquisition timing. After that, continue to acquire voltage, current, and temperature.

In step S12b, the battery pack control unit 150b uses the memory control unit 155 to determine whether the temperature acquired in step S10 is within a predetermined temperature range. As a result, if the value of the acquired temperature T is within a predetermined temperature range, for example, within the range of 35° C. or higher and 40° C. or lower, the process proceeds to step S20. If not, the process returns to step S10 and waits until the next acquisition timing. After that, continue to acquire voltage, current, and temperature.

In steps S20 and S30, the assembled battery control unit 150b performs the same processes as described with reference to FIG. In step S40b, the battery pack control unit 150b causes the storage control unit 155 to associate the SOC and voltage drop values obtained by the SOC estimation unit 152 and the voltage drop calculation unit 153 in steps S20 and S30, respectively, and 151 map information. Note that, unlike the process of step S40 in FIG. 6 described in the first embodiment, it is not necessary to record the current and temperature values in the map information here. However, the current and temperature values may be recorded in the map information. As a result, map information combining at least the SOC and voltage drop values is stored in the storage unit 151, and when predetermined current conditions and temperature conditions are satisfied, map information is calculated each time the SOC and voltage drop values are calculated. Information is updated.

In steps S50, S80, and S90, the assembled battery control unit 150b performs the same processes as described with reference to FIG. Note that when the current and temperature values are recorded in the map information as described above, the SOC and voltage drop values in the map information can be converted to current and temperature by further executing the processing of steps S60 and S70 in FIG. After classifying into a plurality of groups according to the number of data and extracting the values of SOC and voltage drop included in the group having the largest number of data, steps S80 and S90 may be performed. After executing step S90, the assembled battery control unit 150b ends the process shown in the flowchart of FIG.

According to the third embodiment of the present invention described above, in addition to the effects (1) to (5) described in the first embodiment, the following effects are obtained.

(8) In the map information, when the current of the assembled battery 110 is within a predetermined current rate range and the temperature of the assembled battery 110 is within a predetermined temperature range, the SOC estimator 152 and the voltage drop calculator 153 The SOC value and the voltage drop value obtained by are recorded. Using the SOC value and the voltage drop value recorded in the map information, use SOC determining unit 154 determines the range of SOC to be used in charging and discharging assembled battery 110 (steps S80 and S90). In this way, while reducing the amount of data collected in the map information, the optimal SOC range for charging and discharging the assembled battery 110 can be obtained from the SOC and voltage drop values at the current and temperature at which the assembled battery 110 is frequently used. can be determined.

In the above-described third embodiment, the storage control unit 155 executes the processes of steps S11b and S12b, so that when both the current condition and the temperature condition are satisfied, the values of the SOC and the voltage drop are stored in the map information. However, by executing only one of the processes in steps S11b and S12b, the SOC and voltage drop values are recorded in the map information when either the current condition or the temperature condition is satisfied. good too. That is, in the map information, when the current of the assembled battery 110 is within a predetermined current rate range or the temperature of the assembled battery 110 is within a predetermined temperature range, the SOC estimation unit 152 and the voltage drop calculation unit The SOC value and the voltage drop value respectively obtained by 153 may be recorded.

Further, in the above-described third embodiment, an example has been described in which the used SOC determination unit 154 determines the range of SOC used in charging and discharging the assembled battery 110 by executing the processes of steps S80 and S90. , as described in the second embodiment, the central value of the SOC used in charging and discharging the assembled battery 110 may be determined.

<Fourth Embodiment>
Next, a fourth embodiment of the invention will be described. In this embodiment, instead of the assembled battery control units 150, 150a, and 150b described in the first to third embodiments, an assembled battery control unit 150c described below is used to control charging and discharging of the assembled battery 110. An example of doing so will be explained.

FIG. 12 is a block diagram showing details of processing performed by the assembled battery control unit 150c in the fourth embodiment of the present invention. The assembled battery control unit 150c of FIG. 12 differs from the assembled battery control unit 150b of the third embodiment shown in FIG. 154, the information of the used SOC center value is output instead of the used SOC range. Other than this, the configuration is similar to that of the assembled battery control unit 150b.

FIG. 13 is a flow chart showing the flow of processing performed by the assembled battery control unit 150c in the fourth embodiment of the present invention. The assembled battery control unit 150c of the present embodiment executes the process shown in the flowchart of FIG. 13 at predetermined processing intervals, for example, while the assembled battery 110 is being charged and discharged.

In steps S10 to S30, the assembled battery control unit 150c performs the same processes as described with reference to FIG. In step S31c, the battery pack control unit 150c uses the memory control unit 155 to specify to which of a plurality of preset SOC categories the SOC value estimated by the SOC estimation unit 152 in step S20 belongs. . Here, in the map information, a plurality of SOC divisions are set in advance at predetermined SOC intervals within a predetermined SOC range. For example, four SOC divisions are set in 5% increments in the SOC range of 40-60%. In step S31c, it is specified to which of these SOC categories the SOC value estimated in step S20 belongs.

In step S32c, the battery pack control unit 150c causes the storage control unit 155 to determine whether or not a predetermined upper limit number n of voltage drop data has already been recorded in the map information for the SOC category identified in step S31c. determine whether Here, the upper limit number n of data for each SOC segment is predetermined for each SOC segment, and is, for example, n=5. Note that the value of n can be arbitrarily set as long as it is an integer of 1 or more, and a different value may be set for each SOC division. Also, the value of n may be changed according to the data collection period. As a result of the determination in step S32c, if n pieces of data have not yet been recorded in the map information in the SOC division, the process proceeds to step S33c, and if already recorded, the process proceeds to step S40c.

In step S33c, the battery pack control unit 150c causes the storage control unit 155 to store the voltage drop value calculated by the voltage drop calculation unit 153 in step S30 and the data recorded in the map information in the SOC category specified in step S31c. Compare with the voltage drop value shown. As a result, if a larger voltage drop value than any of the data recorded in the map information is calculated, the process proceeds to step S40c. If the data is smaller than the minimum value, the process proceeds to step S50c.

In step S40c, the battery pack control unit 150c causes the storage control unit 155 to associate the SOC and voltage drop values obtained by the SOC estimation unit 152 and the voltage drop calculation unit 153 in steps S20 and S30, respectively, and 151 map information. Here, the SOC and voltage drop values are recorded in the map information in association with the SOC category identified in step S31c. If n pieces of data have already been recorded in the SOC section, the one with the smallest voltage drop value is deleted, and instead the SOC and voltage drop values obtained this time are newly recorded. replaces the map information data. At this time, only the voltage drop value may be recorded without recording the SOC value. Also, the values of the current and the temperature may be recorded in the map information as in step S40b of FIG. 11 described in the third embodiment. As a result, in the map information, the voltage drop values are stored in the storage unit 151 in descending order of the voltage drop value at predetermined SOC intervals, and the voltage drop calculation unit 153 records the voltage drop values in the map information. When a voltage drop larger than the value of the voltage drop given is calculated, the map information is updated.

In step S50c, the battery pack control unit 150c determines whether or not the map information stored in the storage unit 151 records the upper limit number n of data in all the SOC categories. By repeating the process of step S40c at least n times for each SOC division, if n pieces of data representing voltage drop values are recorded in each SOC division in the map information, an affirmative determination is made in step S50c. Proceed to step S80c. On the other hand, if the number of times of processing in step S40c so far is insufficient and there is an SOC section in which n pieces of data are not recorded in the map information, a negative decision is made in step S50c and the process returns to step S10. repeat the process. Thus, data recording to the map information is continued until sufficient data to be used for determining the center SOC is obtained.

In step S80c, the battery pack control unit 150c causes the use SOC determination unit 154 to use the voltage drop values recorded in the map information to calculate the average value of n voltage drops for each SOC category. Here, a plurality of SOC divisions preset in the map information as described above, for example, four SOC divisions set in increments of 5% in the SOC range of 40 to 60% are recorded in the map information. Calculate the average value of the voltage drop in n pieces of data.

In step S81c, the battery pack control unit 150c uses the use SOC determination unit 154 to specify the SOC category in which the average value of the voltage drop calculated in step S80c is the minimum. Then, this SOC division is determined as the central SOC when the assembled battery 110 is charged and discharged. By using the SOC division specified at this time as the central SOC as it is, the central value of the SOC used for charging and discharging the assembled battery 110 may be determined within a range corresponding to the step size of the SOC division. Alternatively, any SOC value within the specified SOC division may be specified and determined as the central SOC.

The use SOC determination unit 154 of the assembled battery control unit 150c determines the assembled battery based on the relationship between the SOC estimated by the SOC estimation unit 152 and the voltage drop calculated by the voltage drop calculation unit 153 by the processing described above. It is possible to determine the center value of SOC used in charging and discharging of 110. After executing step S81c, the assembled battery control unit 150c ends the process shown in the flowchart of FIG.

According to the fourth embodiment of the present invention described above, the effects of (1) to (5) described in the first embodiment and (6) and (7) described in the second embodiment In addition to the functions and effects of the above, the following functions and effects are obtained.

(9) In the map information, voltage drop values are recorded for a predetermined upper limit number n in descending order of voltage drop values in predetermined SOC increments. Using the voltage drop value recorded in the map information, the use SOC determination unit 154 calculates the average value of the voltage drop at the upper limit number n at predetermined SOC intervals (step S80c), and calculates the calculated SOC at predetermined SOC intervals. Using the average value of the voltage drop for each step, the center value of the SOC used in charging and discharging the assembled battery 110 is determined (step S81c). Since this is done, while reducing the amount of data collected in the map information, the optimal SOC for charging and discharging the assembled battery 110 can be determined from the maximum value of the voltage drop measured near the maximum current during charging and discharging of the assembled battery 110. A central value can be determined.

(10) When the voltage drop calculator 153 calculates a voltage drop larger than the voltage drop recorded in the map information (step S33c: Yes), the memory controller 155 updates the map information (step S40c). By doing so, the value of the voltage drop recorded in the map information can be kept up-to-date.

In the above-described fourth embodiment, the use SOC determining unit 154 performs the processes of steps S80c and S81c to determine the central value of the SOC used in charging and discharging the assembled battery 110. However, as described in the first embodiment and the third embodiment, the range of SOC used in charging and discharging the assembled battery 110 may be determined.

<Fifth Embodiment>
Next, a fifth embodiment of the invention will be described. In this embodiment, instead of the assembled battery control units 150, 150a, 150b, and 150c described in the first to fourth embodiments, an assembled battery control unit 150d described below is used to charge the assembled battery 110. An example in which deterioration determination is performed together with discharge control will be described.

FIG. 14 is a block diagram showing details of processing performed by the assembled battery control unit 150d in the fifth embodiment of the present invention. The assembled battery control unit 150d of FIG. 14 differs from the assembled battery control unit 150 of the first embodiment shown in FIG. Except for this point, the configuration is similar to that of the assembled battery control unit 150 .

The voltage drop value output from the voltage drop calculation unit 153 is input to the deterioration determination unit 156 . The deterioration determination unit 156 determines the degree of deterioration of the assembled battery 110 based on the input voltage drop value. For example, by accumulating voltage drop values from the start of operation of the battery system 100 and determining how much the internal resistance has increased in each unit cell 111 of the assembled battery 110 from the state of change, the The degree of deterioration can be determined. The deterioration determination unit 156 outputs information on the determined degree of deterioration to the cell management unit 120 and the vehicle control unit 200 .

According to the fifth embodiment of the present invention described above, in addition to the effects (1) to (10) described in the first to fourth embodiments, the following effects are obtained.

(11) The assembled battery control unit 150 d further includes a deterioration determination unit 156 that determines the degree of deterioration of the assembled battery 110 based on the voltage drop calculated by the voltage drop calculation unit 153 . Since this is done, it is possible to know how much the assembled battery 110 has deteriorated.

In the fifth embodiment described above, an example in which the assembled battery control unit 150d described in the first embodiment is combined with the deterioration determination unit 156 to configure the assembled battery control unit 150d has been described. The assembled battery control units 150a to 150c and the deterioration determination unit 156 described in the fourth embodiment may be combined. Moreover, it is also possible to combine these modified examples described above with the deterioration determination unit 156 .

According to each of the embodiments described above, the use SOC determining unit 154 determines the range or median value of the SOC to be used for charging and discharging the assembled battery 110 mounted on the electric vehicle while the electric vehicle is running. can be changed.

In each of the embodiments described above, depending on the charging/discharging state of the assembled battery 110, the SOC range in which the voltage drop value can be obtained during charging/discharging is narrow, and the SOC range necessary for the map information cannot be sufficiently covered. Sometimes. In such a case, for an SOC range in which voltage drop data is insufficient, data may be interpolated by obtaining a voltage drop value from acquired data by extrapolation. Alternatively, by referring to the SOC value recorded in the map information and controlling the charging/discharging of the assembled battery 110 in the SOC range where the data is insufficient, the data of the voltage drop in the required SOC range can be obtained. can be obtained.

Further, in each of the embodiments described above, each component of the assembled battery control units 150, 150a to 150d may be realized by software executed by a microcomputer or the like, or may be realized by FPGA (Field-Programmable Gate Array). ) or the like. Moreover, you may use these in mixture.

The embodiments and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Moreover, although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

100: battery system, 110: assembled battery, 111: cell, 112: cell group, 120: cell management unit, 121: cell control unit, 122: voltage detection circuit, 123: control circuit, 124: signal input Output circuit 125: temperature detection unit 130: current detection unit 140: voltage detection unit 150, 150a, 150b, 150c, 150d: assembled battery control unit 151: storage unit 152: SOC estimation unit 153: voltage 154: Use SOC determination unit 155: Storage control unit 156: Degradation determination unit 160: Signal communication means 170: Insulating element 200: Vehicle control unit 300a to 300d: Relays 400: Inverter 410: motor generator, 420: charger

Claims (11)

an SOC estimation unit that estimates the SOC (state of charge) of the secondary battery;
A voltage drop calculation unit that calculates a voltage drop based on OCV (open circuit voltage) and CCV (closed circuit voltage) of the secondary battery;
A use SOC that determines a range or center value of the SOC used in charging and discharging the secondary battery based on the relationship between the SOC estimated by the SOC estimation unit and the voltage drop calculated by the voltage drop calculation unit a determining unit ;
The secondary battery control device , wherein the SOC and the voltage drop are values classified according to current and temperature of the secondary battery. In the secondary battery control device according to claim 1,
further comprising a storage unit that stores map information representing the relationship between the SOC and the voltage drop;
The map information includes a plurality of SOC values estimated at different timings by the SOC estimating unit during charging and discharging of the secondary battery, and the voltage drop computing unit computed at timings synchronized with the SOC estimating unit. A secondary battery control device in which a plurality of voltage drop values obtained by the above are recorded in association with each other. In the secondary battery control device according to claim 2,
The use SOC determining unit calculates the average value of the voltage drop for each predetermined SOC range based on the map information, and determines the SOC range in which the calculated average value of the voltage drop is the minimum. A secondary battery control device that determines the range of SOC used in discharging. In the secondary battery control device according to claim 2,
The use SOC determination unit specifies an SOC value that minimizes the voltage drop based on the map information, and uses the specified SOC value as a central value of the SOC used in charging and discharging the secondary battery. Determining secondary battery controller. In the secondary battery control device according to any one of claims 2 to 4,
The current and temperature of the secondary battery are further associated and recorded in the map information,
The used SOC determination unit classifies each data obtained by combining the SOC value and the voltage drop value corresponding in the map information into a plurality of groups based on the current and the temperature, and classifies the plurality of classified data into a plurality of groups. Secondary battery control for determining the SOC range or center value used in charging and discharging the secondary battery by using the SOC value and the voltage drop value included in the group having the largest number of data among the groups. Device. In the secondary battery control device according to any one of claims 2 to 4,
In the map information, when the current of the secondary battery is within a predetermined current rate range and/or the temperature of the secondary battery is within a predetermined temperature range, the SOC estimator and the voltage drop The SOC value and the voltage drop value respectively acquired by the calculation unit are recorded,
The use SOC determination unit uses the SOC value and the voltage drop value recorded in the map information to determine a range or central value of the SOC used in charging and discharging the secondary battery. Battery controller. In the secondary battery control device according to any one of claims 2 to 4,
In the map information, a predetermined upper limit number of voltage drop values are recorded in descending order of the voltage drop value in predetermined SOC increments,
The use SOC determination unit uses the voltage drop values recorded in the map information to calculate the average value of the voltage drop in the upper limit number in units of the predetermined SOC, and calculates the calculated predetermined SOC. A secondary battery control device for determining a range or central value of SOC used in charging/discharging of the secondary battery by using an average value of the voltage drop for each interval. In the secondary battery control device according to claim 7,
The storage unit updates the map information when the voltage drop calculation unit calculates a voltage drop larger than the voltage drop value recorded in the map information. In the secondary battery control device according to any one of claims 2 to 4,
When data obtained by combining the corresponding SOC value and the voltage drop value in the map information are recorded in a predetermined number or more, the use SOC determination unit determines the SOC to be used in charging/discharging the secondary battery. A secondary battery controller that determines a range or center value. In the secondary battery control device according to any one of claims 1 to 4,
The secondary battery is mounted on an electric vehicle,
The used SOC determination unit is a secondary battery control device that changes the range or center value of the SOC used in charging and discharging the secondary battery while the electric vehicle is running. In the secondary battery control device according to any one of claims 1 to 4,
The secondary battery control device further comprising a deterioration determination unit that determines the degree of deterioration of the secondary battery based on the voltage drop calculated by the voltage drop calculation unit.

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