JP5454433B2 - Secondary battery diagnostic device and diagnostic method - Google Patents

Description

  The present invention relates to a technique for diagnosing deterioration of a secondary battery.

  In recent years, electric vehicles (hybrid vehicles, electric vehicles, etc.) that obtain driving force with electric power have attracted a great deal of attention. An electric vehicle generally includes a secondary battery that stores electric power for driving a motor. Secondary batteries deteriorate over time and fail when used continuously in a deteriorated state. Therefore, in an electric vehicle, it is important to grasp the degree of deterioration of the secondary battery. In relation to this point, for example, Japanese Patent Laying-Open No. 2010-86901 (Patent Document 1) estimates the amount of dendrite (resin-like crystal) deposited in the lithium secondary battery and diagnoses deterioration. A technique for performing is disclosed.

  The lithium secondary battery deterioration diagnosis apparatus described in Japanese Patent Application Laid-Open No. 2010-86901 is a first that corresponds to a case where the voltage between terminals of a lithium secondary battery is 50% (SOC (ratio of charged amount to full charge capacity)) The amount of dendrite deposited on the basis of the current value at the time when the elapsed time after the decrease to the second voltage reaches a predetermined time is decreased from the voltage of the first to the second voltage corresponding to the case where the SOC is 0%. presume.

JP 2010-86901 A JP 2008-96442 A International Publication No. 2008/026476 Pamphlet

  When performing deterioration diagnosis of a secondary battery using the technology disclosed in Japanese Patent Application Laid-Open No. 2010-86901, the voltage between terminals of the secondary battery is reduced from the first voltage corresponding to the case where the SOC is 50% to the SOC of 0. It is necessary to lower the voltage to the second voltage corresponding to the case of%.

  However, when considering the use environment of the vehicle, it is difficult to always maintain the voltage between the terminals of the secondary battery at the first voltage or higher (that is, always maintain the SOC at 50% or higher). Therefore, there is a case where the voltage between the terminals of the lithium secondary battery becomes less than the first voltage at the start of the deterioration diagnosis. In this case, a necessary voltage drop amount cannot be secured, and the accuracy of the deterioration diagnosis is not guaranteed. Will fall.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to accurately perform a deterioration diagnosis of a secondary battery regardless of the state of the secondary battery.

  The secondary battery diagnosis apparatus according to the present invention discharges from the secondary battery and discharges the secondary battery while the voltage of the secondary battery drops from the first voltage to the second voltage lower than the first voltage. Is calculated as a diagnostic discharge amount, and a diagnostic unit that performs a deterioration diagnosis of the secondary battery based on the diagnostic discharge amount. When the voltage of the secondary battery at the start of discharge is a third voltage lower than the first voltage, the calculation unit calculates the first value of the secondary battery while the voltage of the secondary battery decreases from the third voltage to the second voltage. A corrected discharge amount obtained by correcting the current integrated value according to the difference between the first voltage and the third voltage is calculated as a diagnostic discharge amount.

  Preferably, the corrected discharge amount is a value obtained by adding an additional discharge amount corresponding to the difference between the first voltage and the third voltage to the first current integrated value.

  Preferably, the additional discharge amount is set to a larger value as the difference between the first voltage and the third voltage is larger.

  Preferably, the corrected discharge amount is a value obtained by adding an additional discharge amount corresponding to the difference between the first voltage and the third voltage and the first current integrated value to the first current integrated value.

  Preferably, the additional discharge amount is set to a larger value as the difference between the first voltage and the third voltage is larger and as the first current integrated value is larger.

  Preferably, the corrected discharge amount is a value obtained by adding an additional discharge amount according to the difference between the first voltage and the third voltage, the first current integrated value, and the temperature of the secondary battery to the first current integrated value.

  Preferably, when the voltage of the secondary battery at the start of discharge is higher than the first voltage, the calculation unit calculates the second current of the secondary battery while the voltage of the secondary battery decreases from the first voltage to the second voltage. The integrated value is calculated as a diagnostic discharge amount.

  Preferably, the secondary battery is configured by connecting a plurality of battery blocks in series. The calculation unit calculates a corrected discharge amount as a diagnostic discharge amount for a battery block whose voltage at the start of discharge is less than the first voltage among the plurality of battery blocks, and the voltage at the start of discharge is higher than the first voltage. For a high battery block, the second integrated current value is calculated as the diagnostic discharge amount.

Preferably, the secondary battery is a lithium ion secondary battery.
A diagnostic method according to another aspect of the present invention is a diagnostic method performed by a secondary battery diagnostic device, wherein the secondary battery is discharged from the first voltage to the first voltage lower than the first voltage. A step of calculating a discharge amount of the secondary battery while the voltage is lowered to the second voltage as a diagnosis discharge amount, and a step of performing a deterioration diagnosis of the secondary battery based on the diagnosis discharge amount. In the calculating step, when the voltage of the secondary battery at the start of discharge is a third voltage lower than the first voltage, the secondary battery voltage decreases while the voltage of the secondary battery decreases from the third voltage to the second voltage. And calculating a corrected discharge amount obtained by correcting the one-current integrated value according to the difference between the first voltage and the third voltage as a diagnostic discharge amount.

  According to the present invention, deterioration diagnosis of a secondary battery can be accurately performed regardless of the state of the secondary battery.

It is a block diagram which shows schematic structure of the vehicle provided with the secondary battery diagnosed with a diagnostic apparatus. It is a figure which shows the structure of a battery, a temperature sensor, a voltage sensor, and a current sensor. It is a functional block diagram of a diagnostic apparatus. 4 is a diagram illustrating a correspondence relationship between a block discharge amount Q and a state of each battery block 11. FIG. It is a figure which shows the content of the calculation process in case discharge start voltage V0 is lower than measurement start voltage Vs. It is a map which shows the correspondence of voltage difference (DELTA) V0, electric current integrated value ∫Ib ', and additional discharge amount q. It is the figure which showed the relationship between block discharge amount Q and electric current integration value ∫Ib 'about each of a new battery and a deterioration battery. It is a flowchart (the 1) which shows the process sequence of a diagnostic apparatus. It is a flowchart (the 2) which shows the process sequence of a diagnostic apparatus. It is a flowchart (the 3) which shows the process sequence of a diagnostic apparatus. It is an image figure of the map for calculating additional discharge amount q by using voltage difference (DELTA) V0, electric current integrated value ∫Ib ', and battery temperature Tb as a parameter.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is a block diagram showing a schematic configuration of vehicle 5 provided with a secondary battery diagnosed by diagnostic device 300 according to the embodiment of the present invention. Although the vehicle 5 shown in FIG. 1 is a hybrid vehicle, the present invention is not limited to the hybrid vehicle and can be applied to all electric vehicles.

  Referring to FIG. 1, vehicle 5 includes a battery 10, system main relays 22 and 24, a power control unit (hereinafter referred to as “PCU”) 30, motor generators 41 and 42, and an engine 50. , A power split mechanism 60, a drive shaft 70, and wheels 80.

  The battery 10 is a lithium ion secondary battery. The battery 10 is configured by connecting a plurality of lithium ion secondary battery cells in series.

  The engine 50 outputs kinetic energy by the combustion energy of fuel. Power split device 60 is connected to motor generators 41 and 42 and the output shaft of engine 50, and drives drive shaft 70 by the output of motor generator 42 and / or engine 50. The wheels 80 are rotated by the drive shaft 70. As described above, the vehicle 5 travels by the output of the engine 50 and / or the motor generator 42.

  Although the motor generators 41 and 42 can function as both a generator and an electric motor, the motor generator 41 mainly operates as a generator, and the motor generator 42 mainly operates as an electric motor.

  Specifically, the motor generator 41 is used as a starter that starts the engine 50 when an engine start request is made, such as during acceleration. At this time, the motor generator 41 receives power supplied from the battery 10 via the PCU 30 and drives as an electric motor, and cranks and starts the engine 50. Further, after the engine 50 is started, the motor generator 41 is rotated by the engine output transmitted through the power split mechanism 60 and can generate electric power.

  Motor generator 42 is driven by at least one of the electric power stored in battery 10 and the electric power generated by motor generator 41. The driving force of the motor generator 42 is transmitted to the driving shaft 70. As a result, the motor generator 42 assists the engine 50 to cause the vehicle 5 to travel, or causes the vehicle 5 to travel only by its own driving force.

  Further, at the time of regenerative braking of the vehicle 5, the motor generator 42 operates as a generator by being driven by the rotational force of the wheels. At this time, the regenerative power generated by the motor generator 42 is charged to the battery 10 via the PCU 30.

  The PCU 30 performs bidirectional power conversion between the battery 10 and the motor generators 41 and 42, and the motor generators 41 and 42 are operated so as to operate according to their operation command values (typically torque command values). Control power conversion. For example, PCU 30 includes an inverter that converts DC power from battery 10 into AC power and applies it to motor generators 41 and 42. This inverter can also convert the regenerative power generated by the motor generators 41 and 42 into DC power and charge the battery 10.

  System main relays 22 and 24 are provided between PCU 30 and battery 10. The system main relays 22 and 24 are turned on / off in response to the relay control signal SE. When the system main relays 22 and 24 are turned off (opened), the charge / discharge path of the battery 10 is mechanically interrupted.

  The vehicle 5 further includes a monitoring unit 20 for monitoring the battery 10 and a control circuit 100.

  The monitoring unit 20 monitors the detection results of the temperature sensor 12, the voltage sensor 14 and the current sensor 16 provided in the battery 10 and outputs them to the control circuit 100. In FIG. 1, the temperature sensor 12 and the voltage sensor 14 are comprehensively shown, but actually, as shown in FIG. 2 described later, a plurality of the temperature sensors 12 and the voltage sensors 14 are provided.

  FIG. 2 is a diagram illustrating configurations of the battery 10, the temperature sensor 12, the voltage sensor 14, and the current sensor 16.

  The battery 10 is configured by connecting n (n: an integer greater than or equal to 2) battery blocks 11 in series. FIG. 2 illustrates the configuration in the case of n = 4. Each battery block 11 is configured by connecting a plurality of battery cells 10a in series.

  The temperature sensor 12 is provided for each battery block 11. FIG. 2 illustrates a configuration in which one temperature sensor 12 is provided for each battery block 11, but a plurality of temperature sensors 12 may be provided for each battery block 11. . Each temperature sensor 12 detects the temperature of the place where each is installed as the battery temperature Tb.

  One voltage sensor 14 is provided for each battery block 11. Each voltage sensor 14 detects a block voltage Vb (Vb1 to Vbn) that is a voltage between both ends of each battery block 11. FIG. 2 illustrates a configuration in which each battery block 11 detects the block voltages Vb1 to Vb4, respectively.

  The current sensor 16 detects a battery current Ib that is a current flowing through the battery 10. A plurality of current sensors 16 may be provided.

  The detection results of each temperature sensor 12, each voltage sensor 14, and current sensor 16 are transmitted to the control circuit 100 via the monitoring unit 20.

  Returning to FIG. 1, the control circuit 100 includes a CPU (Central Processing Unit) (not shown) and an electronic control unit (ECU: Electronic Control Unit) with a built-in memory. The control circuit 100 stores the detection results of each sensor and the memory. Based on the information and the like, a predetermined calculation process is executed.

  The control circuit 100 sets a torque request value for the motor generators 41 and 42 based on the user's accelerator operation amount and vehicle speed. The control circuit 100 controls the power conversion by the PCU 30 so that the motor generators 41 and 42 operate according to the torque request value. The engine 50 is controlled by another ECU (not shown). In FIG. 1, the control circuit 100 is described as a single unit, but may be two or more separate units.

  The vehicle 5 is configured to be connectable to the diagnostic device 300. In the present embodiment, description will be made assuming that diagnostic device 300 is provided in a repair shop such as a dealer. The diagnostic device 300 may be provided inside the vehicle 5.

  Similar to the control circuit 100, the diagnostic apparatus 300 is configured by an electronic control unit that includes a CPU and a memory (not shown).

  The diagnostic apparatus 300 is operated by a service person working at a repair shop. When the diagnostic device 300 is connected to the vehicle 5, communication between the diagnostic device 300 and the control circuit 100 is possible. Diagnosis device 300 communicates with control circuit 100 to diagnose the deterioration state of battery 10 (hereinafter, diagnosis by diagnosis device 300 is referred to as “battery diagnosis”).

  Hereinafter, battery diagnosis performed by the diagnostic apparatus 300 will be described. When a lithium ion secondary battery such as the battery 10 is used for a long period of time, metallic lithium may be deposited inside the battery 10 and deteriorate.

  When the lithium ion secondary battery is discharged from a lithium ion secondary battery in a region where the charged amount of the lithium ion secondary battery is low (hereinafter referred to as “low SOC region”), the voltage of the lithium ion secondary battery is decreased, but the voltage decrease amount at that time Even if the discharge amount is the same, the larger the lithium deposition amount, the larger the amount. In other words, even with the same voltage drop amount, the greater the lithium deposition amount, the smaller the discharge amount. Hereinafter, such characteristics are also referred to as “low-frequency characteristics” for convenience of explanation.

  The diagnostic apparatus 300 uses this low frequency characteristic to diagnose the deterioration state of the battery 10 due to metallic lithium deposition. Specifically, the diagnostic apparatus 300 determines the discharge amount of the battery block 11 when the block voltage Vb is decreased by a predetermined voltage in the low SOC region (hereinafter referred to as “block discharge amount Q”) for each battery block 11. Based on the calculated block discharge amount Q, the deterioration state of the battery 10 due to metallic lithium deposition is diagnosed.

  FIG. 3 is a functional block diagram of a part related to battery diagnosis of the diagnostic apparatus 300. Each functional block shown in FIG. 3 may be realized by hardware processing using an electronic circuit or the like, or may be realized by software processing such as execution of a program.

  The diagnostic apparatus 300 includes a calculation unit 310 and a diagnostic unit 320. The calculation unit 310 calculates the block discharge amount Q for each battery block 11. Diagnosis unit 320 diagnoses the deterioration state of battery 10 based on block discharge amount Q calculated by calculation unit 310.

  Hereinafter, the calculation unit 310 will be described in detail. Calculation unit 310 includes an integration unit 311 and an end unit 312.

  When the diagnosis device 300 is connected to the vehicle 5, the integrating unit 311 starts communication with the control circuit 100 of the vehicle 5, and information from the control circuit 100 (each battery temperature Tb, each block voltage Vb, battery current Ib). Etc.) or a command is transmitted to the control circuit 100, and the following processing is performed.

  The accumulating unit 311 first determines whether or not a battery diagnosis start condition is satisfied. The battery diagnosis start condition is, for example, a condition that the vehicle 5 is stopped in a state in which each electric device of the vehicle 5 is operable (IG on state), and there is no abnormality in information from the control circuit 100. .

  When the battery diagnosis start condition is satisfied, the integration unit 311 calculates the block discharge amount Q by starting the discharge of the battery 10 and performing a calculation process described later. The electric charge discharged from the battery 10 is charged to an auxiliary battery (not shown) mounted on the vehicle 5 via a DC / DC converter (not shown). In addition, you may make it consume the electric charge which the battery 10 discharged with another electric equipment.

  Hereinafter, the content of the calculation process performed by the integrating unit 311 will be described. The accumulating unit 311 switches the content of the calculation process depending on whether or not the block voltage Vb (hereinafter referred to as “discharge start voltage V0”) when the discharge for the calculation process is started is higher than the measurement start voltage Vs. .

  First, the content of the calculation process when the discharge start voltage V0 is higher than the measurement start voltage Vs will be described. In this case, the integrating unit 311 starts integrating the battery current Ib when the block voltage Vb decreases to the measurement start voltage Vs. The integration unit 311 then, when the block voltage Vb decreases to the measurement end voltage Ve that is lower than the measurement start voltage Vs by a predetermined voltage, or when the integrated value of the battery current Ib becomes equal to or greater than the new product determination threshold A1. The integration of the battery current Ib is terminated, and the integrated value of the battery current Ib at that time is stored in the memory.

  In the following description, the integrated value of the battery current Ib until the block voltage Vb decreases from the measurement start voltage Vs to the measurement end voltage Ve is described as “current integrated value ∫Ib”.

  The measurement start voltage Vs and the measurement end voltage Ve are set in advance to values included in the fluctuation range of the block voltage Vb in the above-described low SOC region (a region where the low frequency characteristics can be used). That is, the integrated current value ∫Ib is the discharge amount of the battery block 11 when the block voltage Vb is lowered by a predetermined voltage (difference between the measurement start voltage Vs and the measurement end voltage Ve) in the low SOC region, that is, the above-described block. This corresponds to the discharge amount Q. Therefore, the integrating unit 311 calculates the block discharge amount Q based on the following equation (1).

Block discharge amount Q = current integrated value ∫Ib (1)
FIG. 4 is a diagram illustrating a correspondence relationship between the block discharge amount Q and the state of each battery block 11. The block discharge amount Q decreases as the lithium deposition amount increases due to the low-frequency characteristics described above. That is, the amount of metal lithium deposited in the corresponding battery block 11 can be grasped by the magnitude of the block discharge amount Q. As shown by the solid line L1 in FIG. 4, the battery block 11 in which the block discharge amount Q is equal to or greater than the new product determination threshold A1 is in a state where metal lithium is hardly deposited (hereinafter referred to as “new product state”). As shown by the broken line L2 in FIG. 4, the battery block 11 in which the block discharge amount Q is less than the new product determination threshold value A1 but larger than the unusable determination threshold value A2 is deteriorated from the new state, but the lithium deposition amount is still It is in a state where it can be used continuously. As shown by the one-dot chain line L3 in FIG. 4, the battery block 11 in which the block discharge amount Q further decreases and becomes smaller than the unusable determination threshold A2 is in a state where the lithium deposition amount is large and cannot be used continuously.

  The accumulating unit 311 performs the calculation process individually for each of the block voltages Vb1 to Vbn (for each battery block 11). Therefore, the block discharge amounts Q1 to Qn are calculated for each of the block voltages Vb1 to Vbn, respectively.

The above is the content of the calculation process when the discharge start voltage V0 is higher than the measurement start voltage Vs.
Note that the two-dot chain line L4 in FIG. 4 indicates the discharge characteristics when the block voltage Vb is further decreased from the measurement end voltage Ve to the overdischarge determination threshold Vlow by the calculation process. In a battery block in which the amount of lithium deposition is very large and the deterioration is remarkable, the block voltage Vb drops to the measurement end voltage Ve earlier than the other battery blocks, and the calculation process is terminated. However, since the calculation process of other battery blocks is continued until an end condition described later is satisfied, discharging is continued even in the battery block for which the calculation process has been completed. As a result, in the battery block that is significantly deteriorated, the block voltage Vb may decrease to the overdischarge determination threshold Vlow as indicated by a two-dot chain line L4 in FIG.

  Next, the content of the calculation process when the discharge start voltage V0 is lower than the measurement start voltage Vs will be described. In this case, the integration unit 311 calculates an integrated value (hereinafter also referred to as “current integrated value ∫Ib ′”) of the battery current Ib until the block voltage Vb decreases from the discharge start voltage V0 to the measurement end voltage Ve. The accumulating unit 311 obtains a difference between the measurement start voltage Vs and the discharge start voltage V0 (hereinafter also referred to as “voltage difference ΔV0”), and an additional discharge amount q corresponding to the voltage difference ΔV0 and the current accumulated value ∫Ib ′. Is calculated. The accumulating unit 311 calculates the block discharge amount Q based on the following equation (2). This is the most characteristic point of the present embodiment.

Block discharge amount Q = current integrated value ∫Ib ′ + additional discharge amount q (2)
FIG. 5 is a diagram showing the content of the calculation process when the discharge start voltage V0 is lower than the measurement start voltage Vs. As shown in FIG. 5, when the discharge start voltage V0 is lower than the measurement start voltage Vs, the current integration value ∫Ib ′ from when the discharge starts until the block voltage Vb decreases to the measurement end voltage Ve is calculated. Even if it is calculated, the value of the current integrated value ∫Ib ′ is smaller than the current integrated value ∫Ib to be originally calculated. Therefore, the integrating unit 311 calculates a value obtained by correcting the current integrated value ∫Ib ′ according to the voltage difference ΔV0 and the current integrated value ∫Ib ′ as the block discharge amount Q. Specifically, the integration unit 311 calculates an additional discharge amount q according to the voltage difference ΔV0 and the current integration value ∫Ib ′, and adds it to the current integration value ∫Ib ′ as shown in the above equation (2). A value obtained by adding the discharge amount q is calculated as a block discharge amount Q.

  FIG. 6 is a map showing a correspondence relationship between the voltage difference ΔV0, the integrated current value ∫Ib ′, and the additional discharge amount q. As shown in FIG. 6, the integration unit 311 increases the additional discharge amount q as the voltage difference ΔV0 increases. This is because the difference between the current integrated value ∫Ib ′ and the current integrated value ∫Ib to be originally calculated increases as the voltage difference ΔV0 increases. Further, the integrating unit 311 increases the additional discharge amount q as the current integrated value ∫Ib ′ increases. This takes into account that the block discharge amount Q changes according to the degree of deterioration.

  FIG. 7 is a diagram showing the relationship between the block discharge amount Q and the current integrated value ∫Ib ′ for each of a new battery and a deteriorated battery. As shown in FIG. 7, when the discharge start voltage V0 is the same, the current integrated value ∫Ib ′ is larger in the new battery than in the deteriorated battery. As shown in FIG. 7, the difference between the current integrated value ∫Ib ′ and the block discharge amount Q (value to be set as the additional discharge amount q) is also larger in the new battery than in the deteriorated battery. That is, the larger the current integrated value ∫Ib ′, the larger the value that should be the additional discharge amount q. Considering this point, the additional discharge amount q is increased as the current integrated value ∫Ib ′ is increased.

The above is the content of the calculation process when the discharge start voltage V0 is lower than the measurement start voltage Vs.
Thus, the integration unit 311 switches the content of the calculation process depending on whether or not the discharge start voltage V0 is higher than the measurement start voltage Vs.

  Returning to FIG. 3, the end unit 312 will be described. The end unit 312 determines whether or not the following end condition is satisfied, and ends the calculation process by the integrating unit 311 when the end condition is satisfied. The termination condition includes a normal termination condition and an interruption termination condition.

The normal end condition is a condition for causing the calculation process by the accumulating unit 311 to end normally and shifting to a battery diagnosis determination process by the diagnosis unit 320. For example, the end unit 312 determines that the normal end condition is satisfied when any of the following (a1) to (a4) is satisfied, and normally ends the calculation process.
(A1) All of the block discharge amounts Q1 to Qn are equal to or greater than the new article determination threshold A1.
(A2) All of the block voltages Vb1 to Vbn are equal to or lower than the measurement end voltage Ve.
(A3) At least one of the block voltages Vb1 to Vbn is equal to or lower than the measurement end voltage Ve, and the corresponding block discharge amount Q is less than the unusable determination threshold A2.
(A4) At least one of the block voltages Vb1 to Vbn is equal to or lower than the overdischarge determination threshold Vlow.

  At the normal end, the integration unit 311 outputs the block discharge amounts Q1 to Qn at the normal end time to the diagnosis unit 320 together with the block voltages Vb1 to Vbn.

On the other hand, the interruption end condition is a condition for forcibly interrupting and ending the calculation process by the integrating unit 311. For example, when any of the following (b1) to (b4) is satisfied, the end unit 312 determines that the stop end condition is satisfied, and forcibly interrupts and ends the calculation process.
(B1) An abnormality occurred in the information from the control circuit 100.
(B2) The battery temperature Tb is outside the predetermined temperature range.
(B3) There was an operation for releasing the IG on state (IG off operation).
(B4) The elapsed time from the start of the calculation process has exceeded the upper limit time.

In the case of termination of interruption, the process is not shifted to the battery diagnosis determination process by the diagnosis unit 320.
Next, the diagnosis unit 320 will be described. Based on block discharge amount Q (Q1 to Qn) and block voltage Vb (Vb1 to Vbn) from calculation unit 310, diagnosis unit 320 diagnoses the deterioration state of battery 10 due to metal lithium deposition. Diagnosis unit 320 includes a determination unit 321 and a setting unit 322.

  When the calculation process ends normally, the determination unit 321 determines whether or not the following first to third conditions are satisfied, and performs a determination process for determining a deterioration state of the battery 10 due to metal lithium deposition according to the result.

  The first condition is a condition that all of the block discharge amounts Q1 to Qn are equal to or greater than the new article determination threshold A1 (see the solid line L1 in FIG. 4). When the first condition is satisfied, the determination unit 321 determines that the battery 10 is “new” and outputs a signal R1 indicating “new”.

  The second condition is that at least one of the block voltages Vb1 to Vbn is equal to or lower than the measurement end voltage Ve, and the corresponding block discharge amount Q is less than the unusable determination threshold A2 (see the one-dot chain line L3 in FIG. 4). This is the condition.

  The third condition is that at least one block voltage Vb is equal to or lower than the overdischarge determination threshold Vlow (see the two-dot chain line L4 in FIG. 4), and all of the block discharge amounts Q1 to Qn are less than the unusable determination threshold A2. It is a condition that.

  When the second condition or the third condition is satisfied, the determination unit 321 determines that the battery 10 is “unusable” and outputs a signal R2 indicating “unusable”.

  When none of the first to third conditions is satisfied (see the broken line L2 in FIG. 4), the determination unit 321 determines that the battery 10 is “usable” and indicates a signal “usable”. R3 is output.

  Note that the determination result of the determination unit 321 is displayed on the display of the diagnostic apparatus 300, the information panel of the vehicle 5, and the like to be notified to the user.

  The setting unit 322 sets the new article determination threshold value A1 and the unusable determination threshold value A2 based on the battery temperature Tb and the battery current Ib during the calculation process. For example, the setting unit 322 considers that the discharge amount decreases in a low temperature state even if the deterioration state of the battery 10 is the same, and as the battery temperature Tb during the calculation process is lower, the new product determination threshold A1 and the unusable determination The threshold value A2 is set to a small value. This prevents erroneous determination of the deterioration state of the battery 10 even in a low temperature state. The new article determination threshold value A1 and the unusable determination threshold value A2 set by the setting unit 322 are output to the determination unit 321 and used for the above-described determination process. The new article determination threshold value A1 and the unusable determination threshold value A2 are also output to the calculation unit 310, and are used for determination of the calculation process and the end condition of the calculation process.

  FIG. 8 is a flowchart showing a processing procedure of the diagnostic apparatus 300 for realizing the above-described function. Each step of the flowchart shown below (hereinafter, step is abbreviated as “S”) may be realized by hardware processing as described above, or may be realized by software processing.

  In S10, diagnostic device 300 determines whether or not the battery diagnosis start condition described above is satisfied. If the battery diagnosis start condition is satisfied (YES in S10), the process proceeds to S20. Otherwise (NO in S10), this process ends.

In S20, diagnostic device 300 starts discharging battery 10.
In S30, diagnostic device 300 performs the calculation process described above. The calculation processing procedure of S30 will be described in detail later with reference to FIG.

  In S40, diagnostic device 300 determines whether or not the above-described termination condition (normal termination condition or interruption termination condition) is satisfied. If the end condition is satisfied (YES in S40), the process proceeds to S50. Otherwise (NO in S40), the process returns to S30. Although FIG. 8 shows a procedure for making the determination in S40 after the calculation process in S30, the determination in S40 is actually performed even during the calculation process in S30. That is, if the end condition is satisfied during the calculation process of S30, the process proceeds to S50.

  In S50, diagnostic device 300 ends the calculation process of S30 and stops discharging of battery 10. In S60, diagnostic device 300 sets new article determination threshold value A1 and unusable determination threshold value A2 by the method described above.

  In S70, diagnostic device 300 performs the determination process described above. The procedure of the determination process in S70 will be described in detail later using FIG.

  FIG. 9 is a flowchart illustrating a processing procedure of the diagnostic apparatus 300 when the calculation process (the process of S30) is performed. This process is executed individually for each battery block 11.

  In S31, diagnostic device 300 determines whether or not discharge start voltage V0 is higher than measurement start voltage Vs. At the start of discharging, there may be a phenomenon in which each block voltage Vb temporarily drops by a predetermined amount α due to the internal resistance of each battery block. In order to eliminate the influence of this phenomenon, in S31, it may be determined whether or not the discharge start voltage V0 is higher than (measurement start voltage Vs + predetermined amount α).

  When discharge start voltage V0 is higher than measurement start voltage Vs (YES in S31), block discharge amount Q is calculated by the processes of S32a to S32f.

  In S32a, diagnostic device 300 determines whether block voltage Vb is lower than measurement start voltage Vs or not. When block voltage Vb falls below measurement start voltage Vs (YES in S32a), the process proceeds to S32b. Otherwise (NO in S32a), the process returns to S32a. In S32b, diagnostic device 300 starts integrating battery current Ib.

  In S32c, diagnostic device 300 determines whether block voltage Vb is lower than measurement end voltage Ve or not. When block voltage Vb falls below measurement end voltage Ve (YES in S32c), the process proceeds to S32e. Otherwise (NO in S32c), the process proceeds to S32d.

  In S32d, diagnostic device 300 continues to integrate battery current Ib. Thereafter, the process returns to S32c.

  In S32e, diagnostic device 300 ends the integration of battery current Ib. The integrated value of the battery current Ib at the end of the integration is the above-described current integrated value ∫Ib.

  In S32f, diagnostic device 300 calculates block discharge amount Q based on the above-described equation (1). That is, the block discharge amount Q = current integrated value ∫Ib.

  On the other hand, when discharge start voltage V0 is lower than measurement start voltage Vs (NO in S31), block discharge amount Q is calculated by the processes of S33a to S33g.

  In S33a, diagnostic device 300 calculates voltage difference ΔV0 (= measurement start voltage Vs−discharge start voltage V0) and stores it in memory. In S33b, diagnostic device 300 starts integrating battery current Ib.

  In S33c, diagnostic device 300 determines whether or not block voltage Vb is lower than measurement end voltage Ve. When block voltage Vb is lower than measurement end voltage Ve (YES in S33c), the process proceeds to S33e. Otherwise (NO in S33c), the process proceeds to S33d.

  In S33d, diagnostic device 300 continues to integrate battery current Ib. Thereafter, the process returns to S33c.

  In S33e, diagnostic device 300 ends the integration of battery current Ib. The integrated value of the battery current Ib at the end of the integration is the above-described current integrated value ∫Ib ′.

  In S33f, diagnostic device 300 calculates additional discharge amount q according to voltage difference ΔV0 and current integrated value ∫Ib ′ (see FIG. 6 described above).

  In S33g, diagnostic device 300 calculates block discharge amount Q based on the above-described equation (2). That is, block discharge amount Q = current integrated value ∫Ib ′ + additional discharge amount q.

  In S34, diagnostic device 300 stores the block discharge amount Q calculated in S32f or S33g in the memory. Since the calculation process is executed individually for each battery block 11, n block discharge amounts Q (block discharge amounts Q1 to Qn) are stored in the memory.

  FIG. 10 is a flowchart illustrating a processing procedure of the diagnosis apparatus 300 when performing the determination process.

  In S71, diagnostic device 300 determines whether the end of the calculation process is a normal end. If it is normal termination (YES in S71), the process proceeds to S72. Otherwise (NO in S71), this process ends and no determination process is performed.

  In S72, diagnostic device 300 determines whether or not the first condition is satisfied. As described above, the first condition is a condition that all of the block discharge amounts Q1 to Qn are equal to or greater than the new article determination threshold A1. If the first condition is satisfied (YES in S72), the process proceeds to S73. Otherwise (NO in S72), the process proceeds to S74.

In S73, diagnostic device 300 determines that battery 10 is “new”.
In S74, diagnostic device 300 determines whether or not the second condition is satisfied. As described above, the second condition is that at least one of the block voltages Vb1 to Vbn is equal to or lower than the measurement end voltage Ve, and the corresponding block discharge amount Q is less than the unusable determination threshold A2. . If the second condition is satisfied (YES in S74), the process proceeds to S75. Otherwise (NO in S74), the process proceeds to S76.

In S75, diagnostic device 300 determines that battery 10 is “unusable”.
In S76, diagnostic device 300 determines whether or not the third condition is satisfied. As described above, the third condition is that at least any one of the block voltages Vb is equal to or lower than the overdischarge determination threshold Vlow, and all of the block discharge amounts Q1 to Qn are less than the unusable determination threshold A2. It is. If the third condition is satisfied (YES in S76), the process proceeds to S75. Otherwise (NO in S76), the process proceeds to S77.

In S77, diagnostic device 300 determines that battery 10 is “usable”.
As described above, diagnostic device 300 according to the present embodiment discharges battery 10 and discharges battery block 11 until block voltage Vb drops from measurement start voltage Vs to measurement end voltage Ve (= block discharge amount). Q) is calculated for each battery block 11, and the deterioration state of the battery 10 is diagnosed based on the calculated block discharge amount Q.

  At this time, when the discharge start voltage V0 is higher than the measurement start voltage Vs, the diagnostic apparatus 300 determines the integrated value of the battery current Ib until the block voltage Vb decreases from the measurement start voltage Vs to the measurement end voltage Ve (= The current integrated value ∫Ib) is defined as a block discharge amount Q.

  On the other hand, when the discharge start voltage V0 is lower than the measurement start voltage Vs, the diagnostic apparatus 300 integrates the battery current Ib (= current) until the block voltage Vb decreases from the discharge start voltage V0 to the measurement end voltage Ve. A value obtained by adding a voltage difference ΔV0 between the measurement start voltage Vs and the discharge start voltage V0 and an additional discharge amount q corresponding to the current integrated value ∫Ib ′ to the integrated value ∫Ib ′) is defined as a block discharge amount Q. Therefore, even when the block voltage Vb cannot ensure a state higher than the measurement start voltage Vs, the block discharge amount Q can be accurately calculated without recharging to improve the accuracy of battery diagnosis. Therefore, battery diagnosis can be performed efficiently and accurately. As a result, user convenience (vehicle merchandise) is improved.

  In the present embodiment, the case where the voltage difference ΔV0 and the current integrated value ∫Ib ′ are used as parameters for calculating the additional discharge amount q has been described, but other parameters may be added. For example, as shown in FIG. 11, a map for calculating the additional discharge amount q using the battery temperature Tb as a parameter in addition to the voltage difference ΔV0 and the current integrated value ∫Ib ′ is obtained by experiment and stored in advance. You may make it calculate the additional discharge amount q corresponding to these parameters using this map at the time of a calculation process. As for the correspondence relationship between the battery temperature Tb and the additional discharge amount q, for example, when the voltage difference ΔV0 and the current integrated value ∫Ib ′ are the same value, the battery temperature Tb is lower than the predetermined temperature. The additional discharge amount q may be increased in accordance with Tb, and the correspondence relationship may be such that the additional discharge amount q is maintained at a substantially constant amount in a region where the battery temperature Tb is higher than a predetermined temperature.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  5 Vehicle, 10 Battery, 10a Battery cell, 11 Battery block, 12 Temperature sensor, 14 Voltage sensor, 16 Current sensor, 20 Monitoring unit, 22, 24 System main relay, 41, 42 Motor generator, 50 Engine, 60 Power split mechanism , 70 drive shaft, 80 wheels, 100 control circuit, 300 diagnostic device, 310 calculation unit, 311 integration unit, 312 termination unit, 320 diagnostic unit, 321 determination unit, 322 setting unit.

Claims (10)

A diagnostic device for a secondary battery,
The secondary battery is discharged from the secondary battery, and the secondary battery discharge amount is calculated as a diagnostic discharge amount while the voltage of the secondary battery decreases from the first voltage to the second voltage lower than the first voltage. A calculation unit;
A diagnosis unit that performs deterioration diagnosis of the secondary battery based on the discharge amount for diagnosis,
When the voltage of the secondary battery at the start of discharge is a third voltage lower than the first voltage, the calculation unit is configured to reduce the voltage of the secondary battery from the third voltage to the second voltage. A diagnostic apparatus for a secondary battery, wherein a corrected discharge amount obtained by correcting the first integrated current value of the secondary battery according to a difference between the first voltage and the third voltage is calculated as the diagnostic discharge amount.   2. The diagnostic device for a secondary battery according to claim 1, wherein the corrected discharge amount is a value obtained by adding an additional discharge amount corresponding to a difference between the first voltage and the third voltage to the first integrated current value. .   The diagnostic apparatus for a secondary battery according to claim 2, wherein the additional discharge amount is set to a larger value as a difference between the first voltage and the third voltage is larger.   2. The corrected discharge amount is a value obtained by adding an additional discharge amount corresponding to a difference between the first voltage and the third voltage and the first current integrated value to the first current integrated value. Secondary battery diagnostic device.   The secondary battery according to claim 4, wherein the additional discharge amount is set to a larger value as a difference between the first voltage and the third voltage is larger and as the first current integrated value is larger. Diagnostic equipment.   The corrected discharge amount is a value obtained by adding an additional discharge amount according to the difference between the first voltage and the third voltage, the first current integrated value, and the temperature of the secondary battery to the first current integrated value. The diagnostic apparatus for a secondary battery according to claim 1.   When the voltage of the secondary battery at the start of discharge is higher than the first voltage, the calculation unit is configured to reduce the voltage of the secondary battery from the first voltage to the second voltage. The secondary battery diagnostic device according to claim 1, wherein the second integrated current value is calculated as the diagnostic discharge amount. The secondary battery is configured by connecting a plurality of battery blocks in series,
The calculation unit calculates the corrected discharge amount as the diagnostic discharge amount for a battery block whose voltage at the start of discharge is less than the first voltage among the plurality of battery blocks, and the voltage at the start of discharge is The secondary battery diagnostic device according to claim 7, wherein the second current integrated value is calculated as the diagnostic discharge amount for a battery block higher than the first voltage.   The secondary battery diagnosis apparatus according to claim 1, wherein the secondary battery is a lithium ion secondary battery. A diagnostic method performed by a secondary battery diagnostic device,
The secondary battery is discharged from the secondary battery, and the secondary battery discharge amount is calculated as a diagnostic discharge amount while the voltage of the secondary battery decreases from the first voltage to the second voltage lower than the first voltage. Steps,
Performing a deterioration diagnosis of the secondary battery based on the diagnostic discharge amount,
In the calculating step, when the voltage of the secondary battery at the start of discharge is a third voltage lower than the first voltage, the voltage of the secondary battery is decreased from the third voltage to the second voltage. Calculating a corrected discharge amount obtained by correcting the first current integrated value of the secondary battery according to a difference between the first voltage and the third voltage as the diagnostic discharge amount. Diagnosis method.

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