JP6551362B2 - Power supply system - Google Patents

Description

  The present invention relates to a power supply system including a first power storage device, a second power storage device, and a connection circuit connecting the first power storage device and the second power storage device in parallel.

  In recent years, electric double layer capacitors, lithium ion capacitors, and the like have been used as power sources (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2006-090426

  Power storage devices such as electric double layer capacitors and lithium ion capacitors have the advantage that the charge / discharge power is extremely large compared to secondary batteries, while being stable because the voltage between terminals varies greatly depending on the charging rate. It has the disadvantage that it is difficult to output power. Therefore, in order to compensate each other's disadvantages, it is conceivable to use a combination of a storage device such as an electric double layer capacitor and a lithium ion capacitor and a storage device such as a secondary battery.

  Here, a storage device such as an electric double layer capacitor or a lithium ion capacitor has a high correlation coefficient between the charging rate and the voltage between the terminals, and can accurately calculate the charging rate (or the remaining capacity) from the voltage between the terminals it can. On the other hand, in a power storage device having a low correlation coefficient between the charging rate of a secondary battery or the like and the voltage between terminals, a general configuration is to calculate the charging rate (or remaining capacity) using a current integration method. Here, when the current integration method is used, the calculation accuracy of the charging rate may deteriorate due to the change of the open-circuit voltage-charging rate characteristic or the change of the full charging capacity accompanying the deterioration of the power storage device. I am concerned.

  The present invention has been made in view of the above problems, and a first power storage device having a high correlation coefficient between a charging rate and a voltage between terminals, and a second power storage having a low correlation coefficient between a charging rate and a voltage between terminals. It is a main object of the present invention to accurately calculate the charging rate of the second power storage device in a power supply system used in combination with a device.

  This configuration includes a first power storage device (11) and a second power storage device (12), and a first connection circuit (SWa, SWb) connecting the first power storage device and the second power storage device in parallel. In the power supply system configured as described above, the first power storage device has a correlation coefficient between the charging rate and the inter-terminal voltage of 0.8 or more, and the second power storage device includes the charging rate and the inter-terminal voltage. Calculation of calculating the state of charge of the second power storage device based on the integrated value of the detected values of the charge / discharge current flowing in the second power storage device, the correlation coefficient of which is lower than 0.8 And charging / discharging between the first power storage device and the second power storage device via the first connection circuit in a situation where charging / discharging of the power supply device is stopped, At the start and end of charge / discharge between one power storage device and the second power storage device Based on each detected value of the voltage between the terminals of the first power storage device, the amount of change in the charging rate of the first power storage device due to charging / discharging between the first power storage device and the second power storage device is calculated. A second calculation unit (30) to be calculated, a charging rate of the second power storage device calculated by the first calculation unit, and a change in the charging rate of the first power storage device calculated by the second calculation unit And a correction unit (30) for correcting the calculation of the charging rate of the second power storage device by the first calculation unit based on the amount.

  In this configuration, the first calculation unit calculates the charging rate of the second power storage device based on the current integration method. Further, the second calculation unit performs charge and discharge between the first power storage device and the second power storage device, and calculates a change amount of the charge rate of the first power storage device accompanying the charge and discharge. Then, based on the calculated value of the charging rate of the second power storage device and the calculated value of the change amount of the charging rate of the first power storage device, the charging rate of the second power storage device based on the current integration method by the first calculating unit Correct the calculation.

  Here, since the correlation coefficient between the charging rate of the first power storage device and the voltage between the terminals is high, the second calculation unit accurately calculates the charging rate of the first power storage device based on the voltage between the terminals of the first power storage device. Can be calculated. As a result, the first power storage device 11 based on the voltage between the terminals of the first power storage device at the start and end of charge / discharge when charging / discharging is performed between the first power storage device and the second power storage device. The accuracy of the calculated value of the charging rate change amount is high. Therefore, based on the calculated value of the charging rate of the second power storage device and the calculated value of the change amount of the charging rate of the first power storage device, the charging rate of the second power storage device based on the current integration method by the first calculation unit The calculation accuracy of the charging rate of the second power storage device can be improved by correcting the calculation of.

The electrical block diagram of a power supply system. FIG. 6 is a diagram showing charge and discharge between a first power storage device and a second power storage device. The figure showing the open end voltage-charge rate characteristic of a lithium ion secondary battery and a lithium ion capacitor. The flowchart showing the charging rate calculation process of the 2nd electrical storage apparatus by the electric current integration method. The flowchart showing the correction | amendment process of the open end voltage-charging rate map of a 2nd electrical storage apparatus. The flowchart showing the discharge process of a 1st electrical storage apparatus and a 2nd electrical storage apparatus. The flowchart showing the correction process of the full charge capacity of a 2nd electrical storage apparatus.

  Hereinafter, an embodiment of the present invention will be described based on the drawings. The "power supply system" of the present embodiment is applied to a vehicle, and specifically, used as a power supply of a rotating electrical machine mounted on the vehicle. The vehicle of the present embodiment has an engine (internal combustion engine). The vehicle may have no engine, for example, an electric vehicle.

  FIG. 1 shows the power supply system. The power supply device 10 is connected to the rotating electrical machine 20 via an inverter 21. The power supply device 10 is configured of a first power storage device 11 configured of a lithium ion capacitor and a second power storage device 12 configured of a lithium ion secondary reservoir. Further, the power supply device 10 and the control device 30 that controls the power supply device 10 constitute a “power supply system”.

  The first power storage device 11 is configured by connecting a plurality of lithium ion capacitors 13 in series. By connecting the plurality of lithium ion capacitors 13 in series, the input / output voltage of the entire first power storage device 11 is increased. Note that a series connection of a plurality of lithium ion capacitors 13 may be connected in parallel to be used, or a plurality of lithium ion capacitors 13 may be connected in parallel to be used. By connecting the lithium ion capacitors 13 in parallel, the full charge capacity Ahf1 of the first power storage device 11 is increased.

  The second power storage device 12 is configured by connecting a plurality of battery packs 14 in parallel. The battery assembly 14 is configured by connecting a plurality of battery cells 15 in series. By connecting the plurality of battery cells 15 in series, the input / output voltage of the second power storage device 12 as a whole is increased. Specifically, the battery cell 15 is a lithium ion secondary battery. The open end voltages of the plurality of battery packs 14 are set to be substantially the same. The assembled battery 14 may include a plurality of battery groups in which a plurality of battery cells are connected in parallel or in series with each other, and the plurality of battery groups may be connected in series with or in parallel with each other. By connecting the plurality of battery packs 14 in parallel, the full charge capacity Ahf2 of the entire second power storage device 12 is increased.

  The first power storage device 11 and the second power storage device 12 are configured to be connected in parallel. More specifically, the low voltage side terminal of the first power storage device 11 and the low voltage side terminal of the second power storage device 12 are connected to the low voltage side terminal P− of the power supply device 10, and the first power storage device 10. The high voltage side terminal of the device 11 and the high voltage side terminal of the second power storage device 12 are connected to the high voltage side terminal P + of the power supply device 10.

  A switching element SWa is provided between the first power storage device 11 and the high voltage side terminal P +. The plurality of assembled batteries 14 constituting the second power storage device 12 are each provided with a switching element SWb. A switching element SWc is provided between the power supply device 10 and the inverter 21. The switching element SWa may be provided between the first power storage device 11 and the low voltage side terminal P−, and the switching element SWb is provided between the assembled battery 14 and the low voltage side terminal P−. It may be done. Further, as the switching elements SWa to SWc, a mechanical relay switch, or a semiconductor switching element such as an IGBT or a power MOS-FET may be used.

  Charging / discharging of the 1st electrical storage apparatus 11 is implemented by switching element SWa being turned on. As switching element SWb is turned on, charging / discharging of the corresponding assembled battery 14 is performed. When at least one of the switching elements SWa and SWb is turned on, the switching element SWc is turned on, whereby charging / discharging in the power supply device 10 is performed. Both switching elements SWa and SWb as the “first connection circuit” are turned on, whereby charge and discharge between the first power storage device 11 and the second power storage device 12 are performed. Further, when the switching element SWb as the “second connection circuit” is turned on, the assembled batteries 14 are brought into conduction. The control device 30 implements switching control of the switching elements SWa, SWb, and SWc.

  The rotary electric machine 20 can perform both an operation (powering operation) as a motor that converts electric power into rotational force and an operation (regenerative operation) as a generator that converts rotational power into electric power. The rotary electric machine 20 is connected to an output shaft of the engine 22 via, for example, a belt. The rotating electrical machine 20 starts the engine 22 by applying a rotational force to the output shaft of the engine 22. That is, the rotating electrical machine 20 has a function as an electric motor (starter motor) for starting the engine. Further, by applying rotational force to the output shaft of the engine 22, the rotating electrical machine 20 can assist (assist) the output of the engine 22 at the time of engine combustion during traveling of the vehicle. When the engine is not combusting during traveling, EV (Electric Vehicle) traveling can be performed. In addition, at the time of braking of the vehicle, the rotating electrical machine 20 can perform regenerative power generation using kinetic energy of the vehicle.

  The inverter 21 converts the DC power supplied from the power supply device 10 into AC power, and supplies power to the rotating electrical machine 20 that performs a power running operation. Further, the inverter 21 converts AC power supplied from the rotating electrical machine 20 that performs the regenerative operation into DC power, and charges the power supply device 10. Note that a general electric load other than the inverter 21 and the rotating electrical machine 20 is connected to the power supply device 10, but is omitted in FIG. 1.

  Control device 30 obtains detection values from voltage sensor 31 that detects inter-terminal voltage V1 of first power storage device 11, and temperature sensor 33 that detects temperature T1 of first power storage device 11. The control device 30 acquires the open end voltage of the first power storage device 11 based on the inter-terminal voltage V <b> 1 of the first power storage device 11. Since the internal resistance of the lithium ion capacitor 13 constituting the first power storage device 11 is small, the control device 30 can regard the detected value of the inter-terminal voltage V1 by the voltage sensor 31 as the open end voltage of the first power storage device 11 .

  Control device 30 is based on a map correlating the acquired open end voltage OCV1 of first power storage device 11 with a map correlating open end voltage OCV1 of first power storage device 11 with charge rate SOC1 of first power storage device 11. The charging rate SOC1 of the first power storage device 11 is calculated. Since the open-circuit voltage-charge rate characteristic of the lithium ion capacitor 13 constituting the first power storage device 11 has temperature dependency, the control device 30 determines the first power storage device 11 based on the temperature T1 of the first power storage device 11. Of the open circuit voltage OCV1 and the charge rate SOC1 of the first power storage device 11 are switched.

  Control device 30 has a voltage sensor 34 for detecting inter-terminal voltage V2 of second power storage device 12, a current sensor 35 for detecting charge / discharge current I2 of second power storage device 12, and temperature T2 of second power storage device 12. Detection values are acquired from the temperature sensors 36 to be detected. Control device 30 acquires the detected value of inter-terminal voltage V2 of second power storage device 12 under the condition where charging / discharging in second power storage device 12 is stopped as the open-circuit voltage of second power storage device 12. Here, in order to remove the influence of polarization in second power storage device 12, control device 30 stops charging / discharging in second power storage device 12 and then, after a predetermined time for which the influence of polarization is suppressed, has elapsed. Preferably, the inter-terminal voltage V2 of the second power storage device 12 is acquired as the open end voltage of the second power storage device 12.

  Control device 30 is based on a map that correlates acquired open end voltage OCV2 of second power storage device 12 with a map that associates open end voltage OCV2 of second power storage device 12 with charge ratio SOC2 of second power storage device 12. The charging rate SOC2 of the second power storage device 12 is calculated. Since the open-circuit voltage-charge rate characteristic of the battery cell 15 constituting the second power storage device 12 has temperature dependence, the control device 30 determines the second power storage device 12 based on the temperature T2 of the second power storage device 12. Switching of a map that associates the open end voltage with the charging rate of the second power storage device 12 is performed.

  Here, the voltage sensor 31 may detect a voltage between terminals of each lithium ion capacitor 13 constituting the first power storage device 11, and the control device 30 calculates the charging rate of each lithium ion capacitor 13. You may do. Similarly, voltage sensor 34 may detect a voltage between terminals of each battery cell 15 configuring second power storage device 12, and control device 30 may calculate a charging rate of each battery cell 15. It may be.

  When charge / discharge of second power storage device 12 is started, control device 30 integrates the product of the acquired detected value of charge / discharge current I2 of second power storage device 12 and the predetermined cycle for each predetermined cycle Δt. Then, a change amount ΔAh2 of the charge capacity of the second power storage device 12 is calculated (ΔAh2 = ΣI2 · Δt). Control device 30 calculates the current charging rate of second power storage device 12 based on change amount ΔAh2 of the charge capacity of second power storage device 12 and the charging rate of second power storage device 12 before the start of charging and discharging. Do. Specifically, the charge rate change amount ΔSOC2 is a value obtained by dividing the change amount ΔAh2 of the charge capacity by the full charge capacity Ahf2 of the second power storage device 12, and the charge rate of the second power storage device 12 before the start of charge and discharge (previous value ) To calculate the current charging rate of the second power storage device 12 (ΔSOC2 = ΔAh2 / Ahf2). A method for calculating the charge rate or the charge capacity of the power storage device based on the integrated value of the charge / discharge current as described above is called a current integration method.

  Here, when an error is included in the calculation of the charging rate based on the open end voltage used as an initial value in the current integration method, there is a problem that the error remains. With the deterioration of the battery cell 15 constituting the second power storage device 12, the open-circuit voltage-charge rate characteristic changes. Therefore, if the open end voltage-charge rate map is not corrected according to the deterioration of the second power storage device 12, an error in calculation of the charge rate SOC2 based on the open end voltage becomes large.

  Therefore, control device 30 of the power supply system performs charge and discharge between first power storage device 11 and second power storage device 12, and calculates charge rate change amount ΔSOC1 of first power storage device 11 associated with the charge and discharge. . Then, based on the calculated charging rate change amount ΔSOC1 of the first power storage device 11 and the charging rate SOC2 of the second power storage device 12 calculated by the current integration method, the open end voltage of the second power storage device 12 − Correct the charging rate map. Hereinafter, the correction of the open-circuit voltage-charge rate map of the second power storage device 12 will be described with reference to FIG.

  The difference between the change amount .DELTA.Ah1 of the charge capacity of the first power storage device 11 (LiC) and the change amount .DELTA.Ah2 of the charge capacity of the second power storage device 12 (LiB) shown by the hatched portion in FIG. It corresponds to the power loss associated with charge and discharge with the two power storage devices 12. When the power loss caused by the charge and discharge between the first power storage device 11 and the second power storage device 12 is sufficiently small, the change amount ΔAh1 of the charge capacity of the first power storage device 11 shown by the hatched portion in FIG. The amount of change ΔAh2 of the charge capacity of the storage device 12 is equal to the change amount ΔAh2. That is, the charge rate change amount ΔSOC2 of the second power storage device 12 can be calculated based on the charge rate change amount ΔSOC1 of the first power storage device 11.

  Therefore, control device 30 controls charge rate change amount ΔSOC2 of second power storage device 12 based on charge rate change amount ΔSOC1 of first power storage device 11, and charge rate change amount ΔSOC2 of second power storage device 12 based on the current integration method. The corrected open end voltage-charge ratio map of the second power storage device 12 of the second power storage device 12 is corrected.

  The open end voltage-charge rate characteristic of a lithium ion capacitor and a lithium ion secondary battery is shown in FIG. The open end voltage of the lithium ion capacitor (LiC) linearly changes in accordance with the charging rate. Specifically, the open-circuit voltage of the lithium ion capacitor decreases in proportion to the reduction amount of the charging rate.

  Also, a lithium ion secondary battery (NMC / C type) using nickel manganese cobalt as a positive electrode material and carbon as a negative electrode material, lithium iron phosphate as a positive electrode material, and lithium titanate as a negative electrode material In a lithium ion secondary battery (LFP, LTO system), the open end voltage changes non-linearly according to the charging rate. Specifically, in the lithium ion secondary battery (NMC / C), the open end voltage sharply decreases in the region where the charge rate approaches 0%, and in the lithium ion secondary battery (LFP, LTO system), the charge rate In the region of 10% to 90%, the open end voltage has a plateau region where it hardly changes.

  As the battery cell 15 of the present embodiment, an NMC / C lithium ion secondary battery is used, but an LFP or LTO lithium ion secondary battery may be used. The battery cell 15 has a correlation coefficient between the charging rate and the voltage between terminals lower than 0.8. On the other hand, the lithium ion capacitor 13 is one in which an anion or a cation is adsorbed on at least one of the positive electrode and the negative electrode during charge and discharge, and the correlation coefficient between the charge ratio and the voltage between terminals is 0.8 or more. is there.

  Moreover, the amount of change in the open-circuit voltage with respect to the change in the charging rate of the lithium ion capacitor is larger than that of the lithium ion secondary battery. Furthermore, the internal resistance of the lithium ion capacitor is smaller than that of the lithium ion secondary battery. Therefore, compared to the second power storage device 12 formed of the lithium ion secondary battery, the change amount ΔSOC1 of the charging rate of the first power storage device 11 formed of the lithium ion capacitor 13 is equivalent to that of the first power storage device 11. It can be accurately calculated based on the inter-terminal voltage V1.

  Further, the open end voltage OCV2 of the second power storage device 12 in the fully charged state is set higher than the open end voltage OCV1 of the first power storage device 11 in the fully charged state. Here, since the lithium ion capacitor 13 is larger than the battery cell 15 (lithium ion secondary battery), the open end voltage OCV2 of the second power storage device 12 is reduced due to the decrease in the charging rate. Becomes higher than the open end voltage OCV1 of the first power storage device 11. Thereby, when the first power storage device 11 and the second power storage device 12 are brought into the conductive state by turning on the switching elements SWa and SWb, the first power storage device 12 is not used and the first power storage device 12 is used. It is possible to discharge the power storage device 11.

  FIG. 4 is a flowchart showing a calculation process of the charging rate SOC2 of the second power storage device 12 by the current integration method. The calculation process is performed by the control device 30 at predetermined intervals.

  In step S01, it is determined whether charging / discharging of the 2nd electrical storage apparatus 12 is stopped. It is determined whether the charge / discharge current I2 of the second power storage device 12 is 0 or the change in the voltage V2 across the terminals of the second power storage device 12 as to whether or not the charge / discharge of the second power storage device 12 is stopped. May be determined based on whether or not the switching element SWb is turned off and that the switching element SWb is turned off.

  When charge / discharge of second power storage device 12 is stopped (S01: YES), in step S02, a detected value of temperature T2 of second power storage device 12 is acquired, and voltage V2 across terminals of second power storage device 12 is obtained. Is detected as the open end voltage OCV2 of the second power storage device 12. In step S03, charging rate SOC2 of second power storage device 12 is calculated based on open end voltage OCV2 of second power storage device 12 and open end voltage-charging rate map of second power storage device 12, and the process is ended. Do. The charging rate SOC2 of the second power storage device 12 calculated based on the open-circuit voltage OCV2 is used as an initial value in the current integration method.

  The correspondence relationship between the open end voltage OCV2 of the second power storage device 12 and the charging rate SOC2 of the second power storage device 12 changes in accordance with the temperature T2 of the second power storage device 12. Therefore, control device 30 stores a plurality of open end voltage-charge ratio maps of second power storage device 12 in association with temperature T2 of second power storage device 12, and based on temperature T2 of second power storage device 12. The map is used by switching.

  When charge / discharge of second power storage device 12 is performed (S01: NO), in step S04, the detected value of charge / discharge current I2 of second power storage device 12 is acquired. In step S05, the integrated value (ΣI2 · Δt) of the detected values of the charge / discharge current I2 of the second power storage device 12 is calculated, and the integrated value is divided by the full charge capacity Ahf2 of the second power storage device 12 The amount of change ΔSOC2 of the state of charge of the power storage device 12 is calculated. Then, the current value of the charging rate SOC2 of the second power storage device 12 is calculated by adding the change amount ΔSOC2 of the charging rate to the previous value of the charging rate SOC2 of the second power storage device 12, and the process is ended.

  FIG. 5 is a flowchart showing a correction process for correcting the open-circuit voltage-charge rate map of the second power storage device 12. The correction process is performed by the control device 30 at predetermined intervals.

  In step S11, it is determined whether or not the power supply device 10 is in the process of stopping charging and discharging. If the power supply device 10 is charging / discharging (S11: NO), the process ends. It is determined whether or not the voltage across the terminals of the power supply 10 changes, whether the charge / discharge current of the power supply 10 is zero, or whether the power supply 10 is charging or discharging. It can be determined based on whether the element SWc is in the off state. When power supply device 10 is in the process of stopping charging and discharging (S11: YES), in step S12, charging rate SOC2 of second power storage device 12 calculated in step S05 of FIG. It is acquired as the charging rate SOC2 of the second power storage device 12 before the start of discharge.

  Next, in step S13, the detected value of the terminal voltage V1 of the first power storage device 11, the detected value of the terminal voltage V2 of the second power storage device 12, the detected value of the temperature T1 of the first power storage device 11, and the second The detected value of temperature T2 of power storage device 12 is acquired. In step S14, it is determined whether or not a value obtained by subtracting the inter-terminal voltage V1 of the first power storage device 11 from the inter-terminal voltage V2 of the second power storage device 12 is equal to or greater than a predetermined threshold Th1. If the value obtained by subtracting the inter-terminal voltage V1 from the inter-terminal voltage V2 is smaller than the threshold Th1 (S14: NO), the first storage device 11 and the second storage device 12 are connected even if the first storage device 11 and the second storage device 12 are connected. Since the charge / discharge capacity with respect to power storage device 12 is small and it is difficult to accurately calculate the amount of change in charging rates SOC1, SOC2, processing is performed without carrying out charge / discharge between power storage devices 11, 12. finish.

  If the value obtained by subtracting the inter-terminal voltage V1 from the inter-terminal voltage V2 is greater than or equal to the threshold Th1 (S14: YES), the detected value of the inter-terminal voltage V1 of the first power storage device 11 obtained in step S13 is First, before the start of charging and discharging between the power storage devices 11 and 12 based on the open end voltage of the power storage device 11 and the open end voltage-charge ratio map of the first power storage device 11 1 Charge rate SOC1 of power storage device 11 is acquired.

  Here, the correspondence relationship between the open-circuit voltage OCV1 of the first power storage device 11 and the charging rate SOC1 of the first power storage device 11 changes according to the temperature T1 of the first power storage device 11. For this reason, the control device 30 stores a plurality of open-circuit voltage-charge rate maps of the first power storage device 11 in association with the temperature T1 of the first power storage device 11, and is based on the temperature T1 of the first power storage device 11. The map is used by switching.

  In step S16, both switching elements SWa and SWb are turned on. Thereby, charging / discharging between the 1st electrical storage apparatus 11 and the 2nd electrical storage apparatus 12 is started. In step S17, the detected value of inter-terminal voltage V1 of first power storage device 11, the detected value of inter-terminal voltage V2 of second power storage device 12, the detected value of temperature T1 of first power storage device 11, and the second power storage device 12 detected values of the temperature T2 are obtained.

  In step S18, based on whether or not the detected value of inter-terminal voltage V1 of first power storage device 11 is equal to the detected value of inter-terminal voltage V2 of second power storage device 12, It is determined whether charge and discharge with the storage device 12 are stopped. When charging / discharging between the electrical storage apparatuses 11 and 12 is not stopped (S18: NO), step S17 and S18 are implemented again. It may be determined based on the charge / discharge currents I1, I2 of the power storage devices 11, 12 whether the charge / discharge is performed between the power storage devices 11, 12 or not.

  If it is determined that charge and discharge between power storage devices 11 and 12 are stopped (S18: YES), switching elements SWa and SWb are both turned off in step S19. Thereafter, in step S20, the inter-terminal voltage V2 of the second power storage device 12 is regarded as the open end voltage OCV2, and based on the open end voltage OCV2 and the open end voltage-charge ratio map of the second power storage device 12. The charge rate SOC2 of the second power storage device 12 is calculated. In step S21, the voltage V1 across the terminals of the first power storage device 11 is regarded as the open end voltage OCV1, and based on the open end voltage OCV1 and the open end voltage-charge ratio map of the first power storage device 11, 1 Charge rate SOC1 of power storage device 11 is calculated.

  In step S22, the charging rate change amount ΔSOC1 of the first power storage device 11 due to charging / discharging between the power storage devices 11 and 12 is calculated. Specifically, the difference between the charging rate SOC1 of the first power storage device 11 calculated in step S15 and the charging rate SOC1 of the first power storage device 11 calculated in step S21 is calculated as the charging rate change amount ΔSOC1. In step S23, the charging rate change amount ΔSOC2 of the second power storage device 12 due to charging / discharging between the power storage devices 11 and 12 is calculated. Specifically, the difference between the charging rate SOC2 of the second power storage device 12 acquired in step S12 and the charging rate SOC2 of the second power storage device 12 calculated in step S20 is calculated as the charging rate change amount ΔSOC2.

  Then, in step S24, the open end voltage-charge ratio map of second power storage device 12 is corrected based on the comparison between charge ratio change amount ΔSOC1 and charge ratio change amount ΔSOC2. More specifically, the charging rate change amount ΔSOC2 of the second power storage device 12 based on the charging rate change amount ΔSOC1 of the first power storage device 11 and the charging rate change amount ΔSOC2 of the second power storage device 12 based on the current integration method By comparing, the open end voltage-charge rate map of the second power storage device 12 of the second power storage device 12 is corrected. In step S25, the degree of deterioration of the second power storage device 12 is calculated based on the change in the full charge capacity Afh2 of the second power storage device 12, and the process is ended.

  FIG. 6 is a flowchart showing power supply processing of the power supply device 10. This process is performed by the control device 30 at predetermined intervals.

  In step S31, it is determined whether the discharge power of the power supply device 10 is equal to or greater than a predetermined threshold. Specifically, it is determined whether or not the discharge current of the power supply device 10 that is the sum of the discharge current I1 of the first power storage device 11 and the discharge current I2 of the second power storage device 12 is equal to or greater than a predetermined threshold Th2. The determination as to whether or not the discharge power of the power supply device 10 is greater than or equal to a predetermined threshold value may be made based on the detected values of the discharge currents I1 and I2, or based on the operating state of the electric load including the rotating electrical machine 20. May be determined.

  When the discharge power of the power supply device 10 is equal to or greater than the predetermined threshold (S31: YES), in step S32, the switching element SWa is turned on and the switching element SWb is turned off. By the control of step S32, power output from the first power storage device 11 to the electric load is implemented with priority over power output from the second power storage device 12 to the electric load. The first power storage device 11 bears the power supply from the power supply device 10 to the electric load. When the discharge power of the power supply device 10 is less than the predetermined threshold (S31: NO), the switching element SWa is turned off and the switching element SWb is turned on in step S33. By the control of step S33, power output from the second power storage device 12 to the electric load is implemented with priority over power output from the first power storage device 11 to the electric load.

  The effects of this embodiment will be described below.

  The control device 30 of this configuration calculates the charge rate SOC2 of the second power storage device 12 based on the current integration method as the “first calculation unit”, and the first power storage device 11 as the “second calculation unit”. Charge and discharge with the second power storage device 12 are performed, and change amount ΔSOC1 of the charging rate of the first power storage device 11 accompanying the charge and discharge is calculated. Then, based on the calculated value of the state of charge SOC2 of the second power storage device 12 and the calculated value of the amount of change ΔSOC1 of the state of charge of the first power storage device 11, a second based on the current integration method by the “first calculator” The calculation of the charging rate SOC2 of the power storage device 12 is corrected.

  Here, since the correlation coefficient between state of charge SOC1 of first power storage device 11 and inter-terminal voltage V1 is high, control device 30 accurately determines the first power storage device based on inter-terminal voltage V1 of first power storage device 11. 11 charging rate SOC1 can be calculated. As a result, the change in the charging rate of the first power storage device 11 based on the voltage V1 between the terminals of the first power storage device 11 at the start and end of charge / discharge when charging / discharging between the power storage devices 11 and 12 is performed. The accuracy of the calculated value of the amount ΔSOC1 is high. Therefore, based on the calculated value of state of charge SOC2 of second power storage device 12 and the calculated value of amount of change ΔSOC1 of the state of charge of first power storage device 11, the first calculation unit By correcting the calculation of the charging rate SOC2 of the two power storage device 12, the calculation accuracy of the charging rate SOC2 of the second power storage device 12 can be improved.

  Control device 30 calculates charging rate SOC2 of second power storage device 12 based on the current integration method. Specifically, using the open end voltage OCV2 of the second power storage device 12 at a predetermined time and the open end voltage-charge ratio map of the second power storage 12, the charging rate SOC2 of the second power storage 12 at a predetermined time is calculated. calculate. Then, charging rate SOC2 of second power storage device 12 is added by adding charging rate change amount ΔSOC2 based on the integrated value of detected values of charging / discharging current I2 to charging rate SOC2 of second power storage device 12 at the predetermined time. Calculate Here, with the deterioration of the second power storage device 12, the correspondence between the open end voltage OCV2 and the charging rate SOC2 changes. By changing the correspondence between the open-circuit voltage OCV2 and the charging rate SOC2, the calculated value of the charging rate SOC2 of the second power storage device 12 includes an error.

  Therefore, control device 30 selects second power storage device 12 based on charge rate change amount ΔSOC2 of second power storage device 12 calculated based on the current integration method and charge rate change amount ΔSOC1 of first power storage device 11. The open-circuit voltage-charging rate map of is corrected. By the correction, the calculation accuracy of the charging rate SOC2 of the second power storage device 12 by the control device 30 can be improved.

  Specifically, the control device 30 as the “second calculation unit” detects the open-circuit voltage-charge rate map of the first power storage device 11 and the voltage V2 between the terminals of the first power storage device 11 before and after charging and discharging. Based on the value, the charging rate change amount ΔSOC1 of the first power storage device 11 is calculated. Here, the correspondence between the open-circuit voltage OCV <b> 1 of the first power storage device 11 and the charging rate SOC <b> 1 changes according to the temperature T <b> 1 of the first power storage device 11. Therefore, by switching the open end voltage-charging rate map based on the detected value of temperature T1 of first power storage device 11, it becomes possible to calculate charging rate change amount .DELTA.SOC1, and the second It becomes possible to correct the calculation of the state of charge SOC2 of the power storage device 12.

  The open end voltage OCV2 of the fully charged second power storage device 12 is set higher than the open end voltage OCV1 of the fully charged first power storage device 11. Thereby, when the first power storage device 11 and the second power storage device 12 are brought into conduction, it is possible to discharge the first power storage device 11 from the second power storage device 12 without using a booster circuit or the like. . Also, for example, when a secondary battery having a plateau region is adopted as the second power storage device 12, the open end voltage of the second power storage device 12 is higher than the open end voltage of the first power storage device 11 over the entire plateau region. This facilitates the discharge from the second power storage device 12 to the first power storage device 11 without using a booster circuit or the like.

  The power output from the second power storage device 12 to the electric load is prioritized over the power output from the first power storage device 11 to the electric load (the rotating electrical machine 20). According to this configuration, even when the full charge capacity Ahf1 of the first power storage device 11 is smaller than the full charge capacity Ahf2 of the second power storage device 12, power supply can be stably continued to the electric load. In addition, since a situation occurs in which the open end voltage OCV1 of the first power storage device 11 and the open end voltage OCV2 of the second power storage device 12 are different, charge and discharge are performed between the first power storage device 11 and the second power storage device 12 It becomes possible to carry out.

  When a lithium ion capacitor is used as the power storage element constituting the first power storage device 11 and a secondary battery such as a lithium ion secondary battery is used as the power storage element constituting the second power storage device 12, the output of the second power storage device 12 When the power temporarily increases, polarization occurs in the second power storage device 12, and the calculation accuracy of the charging rate SOC2 of the second power storage device 12 decreases, or the available output power of the second power storage device 12 decreases. Problems such as deterioration of the second power storage device 12 or the like.

  Therefore, in the configuration in which power output from the second power storage device 12 to the electric load is performed with priority over power output from the first power storage device 11 to the electric load, the output power from the power supply device 10 to the electric load is threshold power. The power output from the first power storage device 11 to the electric load is prioritized over the power output from the second power storage device 12 to the electric load on the condition that the power is larger. According to this configuration, it is possible to suppress a temporary increase in the output power of the second power storage device 12 and to suppress the adverse effect of polarization that occurs in the second power storage device 12.

  When the second power storage device 12 is deteriorated, the open end voltage-charge rate characteristic of the second power storage device 12, the full charge capacity Ahf2, and the like change. Therefore, in the present embodiment, the degree of deterioration of the second power storage device 12 is calculated based on the open end voltage-charge rate characteristic of the second power storage device 12.

  The second power storage device includes a plurality of assembled batteries 14 and switches SWb that connect the plurality of assembled batteries 14 to each other in parallel, and the open-circuit voltages of the plurality of assembled batteries 14 are set to be substantially the same. There is. According to this configuration, it is possible to suppress charging / discharging between power storage elements in the second power storage device 12. Moreover, if it is set as the structure which charges / discharges between each of the assembled batteries 14 and the 1st electrical storage apparatus 11, it will become possible to correct | amend calculation of the charging rate of each assembled battery 14. FIG.

Second Embodiment
In the configuration of the first embodiment, the open end voltage-charge rate map of the second power storage device 12 is corrected. However, this is changed, and in the configuration of the second embodiment, the charging rate change amounts ΔSOC1 and ΔSOC2 are changed. Based on the comparison, the full charge capacity Ahf2 of the second power storage device 12 is corrected. Since the full charge capacity Ahf2 of the second power storage device 12 decreases in accordance with the deterioration of the battery cell 15, the full charge capacity Ahf2 of the second power storage device 12 is corrected based on the charge rate change amount ΔSOC1 of the first power storage device 11. By setting it, it becomes possible to implement control according to change of full charge capacity Ahf2 accompanying degradation of battery cell 15 which constitutes the 2nd electricity storage device 12.

  FIG. 6 is a flowchart showing a correction process for correcting the full charge capacity Ahf2 of the second power storage device 12. The correction process is performed by the control device 30 at predetermined intervals. The same processing as the processing shown in FIG. 5 is denoted by the same reference numeral, and the description will not be repeated.

  In the process illustrated in FIG. 6, the process of acquiring the charging rate SOC2 of the second power storage device 12 in step S12 is omitted. In addition, if a negative determination is made in step S18, that is, if charge and discharge are performed between power storage devices 11 and 12, detection of charge / discharge current I2 of second power storage device 12 in step S41. Get the value. In step S42, the charging rate change amount ΔSOC2 of the second power storage device 12 is calculated based on the detected value of the charge / discharge current I2 of the second power storage device 12.

  Thereafter, in step S43 after step S42, based on the charging rate change amount ΔSOC1 of the first power storage device 11 and the charging rate change amount ΔSOC2 of the second power storage device 12, the full charge capacity Ahf2 of the second power storage device 12 Make corrections for More specifically, the discharge capacity discharged from first power storage device 11 to second power storage device 12 is calculated based on charge rate change amount ΔSOC1 of first power storage device 11. Then, by dividing the calculated value of the discharge capacity by the charging rate change amount ΔSOC2 of the second power storage device 12, the full charge capacity Ahf2 of the second power storage device 12 is newly calculated. In step S25 after step 43, the degree of deterioration of the second power storage device 12 is calculated based on the change in the full charge capacity Afh2 of the second power storage device 12, and the process is ended.

(Other embodiments)
The detection of the temperature T1 by the temperature sensor 33 targeting the first power storage device 11 and the switching of the open-end voltage-charge rate map of the first power storage device 11 based on the detected value of the temperature T1 by the control device 30 are omitted. It is good also as composition. Similarly, the detection of the temperature T2 by the temperature sensor 36 targeting the second power storage device 12 and the switching of the open-circuit voltage-charge rate map of the second power storage device 12 based on the detected value of the temperature T2 by the control device 30 are performed. It may be omitted.

  The electricity storage element constituting the first electricity storage device 11 adsorbs an anion or cation in at least one of the positive electrode and the negative electrode during charge and discharge, that is, performs an adsorption type reaction in at least one of the positive electrode and the negative electrode . The storage element that performs the adsorption type reaction is a lithium ion capacitor as described above. By changing this, an electric double layer capacitor or a nano hybrid capacitor may be used instead of the lithium ion capacitor. In an electric double layer capacitor, carbon (activated carbon electrode) is generally used for a positive electrode and a negative electrode. In a nanohybrid capacitor, generally, nanocrystalline lithium titanate is used for the negative electrode, and carbon (activated carbon electrode) is used for the positive electrode.

  The storage element that constitutes the second storage device 12 is a secondary battery, and more specifically, a lithium ion secondary battery. This may be changed, and a nickel metal hydride storage battery or a lead storage battery may be used instead of the lithium ion secondary battery.

  Switching elements are used as the “first connection circuit” and the “second connection circuit”, but a voltage conversion circuit (DCDC) is used instead of the switching element as the “first connection circuit” or the “second connection circuit”. A converter) may be used, or a bypass circuit composed of resistance elements may be used.

  11: first power storage device, 12: second power storage device, 30: control device.

Claims (11)

A first power storage device (11), a second power storage device (12), and a first connection circuit (SWa, SWb) that connects the first power storage device and the second power storage device in parallel. In the power supply system
The first power storage device has a correlation coefficient of 0.8 or more between the charging rate and the voltage across the terminals, and the second power storage device has a correlation coefficient between charging rate and the voltage across the terminals of 0.. Less than 8,
A first calculation unit (30) that calculates a charging rate of the second power storage device based on an integrated value of detected values of charge and discharge currents flowing through the second power storage device;
In a situation where charging / discharging of the power supply system is stopped, charging / discharging is performed between the first power storage device and the second power storage device via the first connection circuit, and the first power storage device and the first power storage device Between the first power storage device and the second power storage device based on the detected values of the voltage across the terminals of the first power storage device at the start and end of charging / discharging between the two power storage devices. A second calculation unit (30) that calculates the amount of change in the charging rate of the first power storage device associated with charging and discharging of
Based on the charge rate of the second power storage device calculated by the first calculation unit and the change amount of the charge rate of the first power storage device calculated by the second calculation unit, the first calculation unit A correction unit (30) that corrects the calculation of the charging rate of the second power storage device;
Power supply system comprising: The first calculation unit is
A map for correlating the open end voltage of the second power storage device with the charging rate of the second power storage device, and the second at a predetermined time before charging and discharging between the first power storage device and the second power storage device. (2) The charging rate of the second power storage device at a predetermined time point is calculated based on the open end voltage of the power storage device,
By adding the amount of change in the charging rate of the second power storage device based on the integrated value of the detected values of the charge / discharge current flowing through the second power storage device to the charging rate of the second power storage device at the predetermined time point, Calculating a charging rate of the second power storage device at the start of charging / discharging between the first power storage device and the second power storage device;
The map that associates the open-circuit voltage of the second power storage device with the charging rate of the second power storage device, and the second at the end of charging / discharging between the first power storage device and the second power storage device. Calculating a charging rate of the second power storage device at the end of charging / discharging between the first power storage device and the second power storage device based on an open end voltage of the power storage device;
The correction unit is a charging rate of the second power storage device at the start of charging / discharging between the first power storage device and the second power storage device calculated by the first calculation unit, and the first power storage. A difference between the charge ratio of the second power storage device at the end of charge / discharge between the device and the second power storage device, and the charge rate of the first power storage device calculated by the second calculation unit The power supply system according to claim 1, wherein a map that correlates an open-end voltage of the second power storage device and a charging rate of the second power storage device is corrected based on a change amount. The first calculation unit is based on an integrated value of detection values of charge / discharge currents flowing through the second power storage device, and from the start to the end of charge / discharge between the first power storage device and the second power storage device. Calculating the amount of change in the charging rate of the second power storage device until
The correction unit is based on the change amount of the charge rate of the second power storage device calculated by the first calculation unit and the change amount of the charge rate of the first power storage device calculated by the second calculation unit. The power supply system according to claim 1, wherein the full charge capacity of the second power storage device is corrected.   The second calculation unit is a map that associates the open end voltage of the first power storage device with the remaining capacity of the first power storage device, charge and discharge between the first power storage device and the second power storage device. The amount of change in the charging rate of the first power storage device is calculated based on the detected value of the voltage across the terminals of the first power storage device at the start and end, and the temperature of the first power storage device is calculated. The power supply system according to any one of claims 1 to 3, wherein a map for associating an open-ended voltage of the first power storage device and a remaining capacity of the first power storage device is switched based on a detection value.   The power supply system according to any one of claims 1 to 4, wherein the open end voltage of the fully charged second power storage device is higher than the open end voltage of the fully charged first power storage device. Electrical load is connected,
The power supply system according to any one of claims 1 to 5, wherein power output from the second power storage device to the electric load is performed in priority to power output from the first power storage device to the electric load.   On condition that the output power from the power supply system to the electric load is larger than a predetermined threshold power, the electric power output from the first electric storage device to the electric load is prioritized over the electric power output from the second electric storage device to the electric load The power supply system according to claim 6, wherein the power output to the power supply is performed.   Based on the charging rate of the second power storage device calculated by the first calculation unit and the charging rate between the first power storage device and the second power storage device calculated by the second calculation unit. The power supply system according to any one of claims 1 to 7, further comprising a deterioration degree calculation unit that calculates a deterioration degree of the second power storage device. The second power storage device includes a plurality of power storage elements (14) and a second connection circuit (SWb) connecting the plurality of power storage elements in parallel with each other,
The power supply system according to any one of claims 1 to 8, wherein open end voltages of the plurality of storage elements are substantially equal to one another.   The power supply system according to any one of claims 1 to 9, wherein the first power storage device includes a power storage element that adsorbs an anion or a cation in at least one of a positive electrode and a negative electrode during charge and discharge. .   The power supply system according to any one of claims 1 to 10, wherein the second power storage device includes a secondary battery.

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