JP5626195B2 - Power storage system - Google Patents

Description

  The present invention relates to a power storage system that determines an abnormality of a power storage device.

  In Patent Document 1, an abnormal internal resistance of a battery is detected from a current value and a voltage value that are sequentially detected. Specifically, an abnormal internal resistance of the battery is detected when a change in voltage when charged or discharged with a predetermined current exceeds a reference value.

JP 2010-117235 A

  Some secondary batteries have a built-in current breaker. When an abnormality occurs in the secondary battery, the current breaker operates to cut off the current. However, there is a possibility that a reconducting phenomenon in which the current breaker conducts again after the operation and the current flows will occur.

  The re-conducting phenomenon after the operation of the current breaker is detected, since the resistance of the secondary battery is extremely increased due to the mechanical and physical resistance increase, resulting in a high resistance state. There is a need to.

  On the other hand, if the current distribution of the charge / discharge current is not sufficiently ensured, there is a problem that it is difficult to grasp the resistance abnormality of the secondary battery due to the detection error of the voltage sensor or the current sensor. In particular, in a state where the charge / discharge current is low, the influence of the detection error of the current sensor becomes large, and a resistance abnormality cannot be detected with high accuracy.

  The power storage system mounted on the vehicle according to the first invention of the present application includes a power storage device in which a plurality of power storage elements each having a current breaker that interrupts a current path are connected in series, and a power storage that is re-conducted after the current breaker is activated. And a controller for determining an abnormal state of the element. The controller operates by receiving power from the power storage device when the temperature difference between the power storage elements is greater than or equal to a predetermined value, and varies the power consumption of the power consuming device connected via the DC / DC converter. Based on the voltage detected by the voltage sensor and the current detected by the current sensor, the resistance of the power storage element indicating the amount of change in voltage relative to the amount of change in current is calculated. When the calculated resistance is higher than the threshold value, it is determined that the power storage element is in an abnormal state.

  According to the first invention of the present application, the temperature difference between the power storage elements is monitored to quickly detect the presence of the unit cell 11 that has been re-conducted after the current breaker in the high resistance state is activated. Since the resistance of the power storage element can be detected with high accuracy by varying the power consumption to ensure current dispersion, the abnormality of the power storage element that is re-conducted after the current circuit breaker is activated can be detected quickly and accurately.

  The controller passes the DC / DC converter when the detected current by the current sensor is less than or equal to the abnormality determination allowable value corresponding to the detection error of the current sensor or when the duration of the abnormality determination allowable value or less is a predetermined time or more. The power consumption of the connected power consuming device can be varied. Even when the charge / discharge is below the abnormality determination allowable value according to the detection error of the current sensor, the power consumption of the power consuming device is fluctuated to ensure current dispersion and accurately detect the resistance of the storage element, It is possible to quickly and accurately detect the abnormality of the storage element that is re-conducted after the current breaker is activated.

  The controller can set the input / output upper limit value of charge / discharge control of the power storage device to be low when the temperature difference between the power storage elements is equal to or greater than a predetermined value. By limiting the upper limit value to a low value, the amount of heat generated by the power storage element can be suppressed.

  A power storage system mounted on a vehicle according to a second invention of the present application includes a power storage device in which a plurality of power storage elements each having a current breaker that interrupts a current path are connected in series, and a temperature sensor that detects temperatures of the plurality of power storage elements And a cooling device that cools the power storage device, and a power storage element that is re-conducted after the current breaker is activated by calculating a temperature rise change amount and a temperature fall change amount per unit time of the power storage element based on a temperature detected by the temperature sensor And a controller for discriminating the abnormal state. The controller drives the cooling device when the temperature increase change amount is equal to or greater than the first threshold value, and the power storage element is in an abnormal state when the temperature change amount due to cooling of the power storage device by the cooling device is equal to or greater than the second threshold value. Determine that there is.

  According to the second invention of the present application, the temperature increase tendency of the storage element in an abnormal state that is re-conducted after the current breaker is activated and the storage element that is not abnormal (the current breaker is not activated) and Based on the difference in the temperature drop tendency, it is possible to accurately and quickly detect the storage element that is re-conducted after the current breaker is activated.

  The second invention of the present application can further include a current sensor that detects a current flowing through the power storage device, and the controller is configured such that when the current detected by the current sensor is equal to or less than an abnormality determination allowable value according to a detection error of the current sensor, Based on the temperature rise change amount and the temperature fall change amount, the abnormal state of each power storage element can be determined. Since the resistance abnormality of the electricity storage element is not detected based on the battery voltage or current value, even if the charge / discharge is below the abnormality determination allowable value according to the detection error of the current sensor, it is restarted after the current breaker is activated. The conductive storage element can be detected accurately and quickly.

  The controller can set the input / output upper limit value of charge / discharge control of the power storage device to be low when the temperature increase change amount is equal to or greater than the first threshold value. By limiting the upper limit value to a low value, the amount of heat generated by the power storage element can be suppressed.

It is a figure which shows the structure of the battery system of Example 1. FIG. 2 is a diagram illustrating an internal configuration of a single battery according to Example 1. FIG. 1 is a configuration block diagram of a battery system of Example 1. FIG. It is a figure which shows the method of calculating the resistance of the cell of Example 1. FIG. It is a figure which shows the relationship between the resistance and electric current value of the cell in which the battery abnormality (re-conduction) of Example 1 occurred. It is a figure explaining the temperature behavior of the battery in which the battery abnormality (re-conduction) of Example 1 occurred. 3 is a flowchart illustrating a process for determining an abnormality of a single battery according to the first embodiment. It is a figure which shows an example of the electric current fluctuation | variation at the time of changing the power consumption of Example 1. FIG. It is a figure explaining the temperature behavior of the battery in which the battery abnormality (re-conduction) of Example 2 occurred. 3 is a configuration block diagram of a battery system of Example 2. FIG. It is a flowchart which shows the process which determines the abnormality of the cell of Example 2.

  Examples of the present invention will be described below.

Example 1
With reference to FIGS. 1-8, the battery system (equivalent to an electrical storage system) which is Example 1 of this invention is demonstrated. FIG. 1 is a diagram illustrating a configuration of a battery system. The battery system of this embodiment is mounted on a vehicle.

  Vehicles include hybrid cars and electric cars. The hybrid vehicle includes an engine or a fuel cell as a power source for running the vehicle in addition to the assembled battery described later. The electric vehicle includes only an assembled battery described later as a power source for running the vehicle. In the embodiments described below, a hybrid vehicle equipped with an engine will be described.

  The assembled battery (corresponding to a power storage device) 10 has a plurality of unit cells (corresponding to power storage elements) 11 connected in series. As the cell 11, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor (capacitor) can be used instead of the secondary battery. The number of unit cells 11 constituting the assembled battery 10 can be appropriately set based on the required output of the assembled battery 10 and the like. In the present embodiment, all the unit cells 11 constituting the assembled battery 10 are connected in series, but the present invention is not limited to this. A plurality of unit cells 11 connected in parallel may be included in the assembled battery 10.

  As shown in FIG. 2, the cell 11 includes a power generation element 11 a and a current breaker 11 b. The power generation element 11 a and the current breaker 11 b are accommodated in a battery case that constitutes the exterior of the unit cell 11. The power generation element 11a is an element that performs charge and discharge, and includes a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate.

  The positive electrode plate includes a current collector plate and a positive electrode active material layer formed on the surface of the current collector plate. The negative electrode plate has a current collector plate and a negative electrode active material layer formed on the surface of the current collector plate. The positive electrode active material layer includes a positive electrode active material and a conductive agent, and the negative electrode active material layer includes a negative electrode active material and a conductive agent.

When a lithium ion secondary battery is used as the single battery 11, for example, the current collector plate of the positive electrode plate can be formed of aluminum, and the current collector plate of the negative electrode plate can be formed of copper. As the positive electrode active material, for example, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ can be used, and as the negative electrode active material, for example, carbon can be used. An electrolyte solution is infiltrated into the separator, the positive electrode active material layer, and the negative electrode active material layer. Instead of using the electrolytic solution, a solid electrolyte layer may be disposed between the positive electrode plate and the negative electrode plate.

  The current breaker 11b is used to cut off the current path inside the unit cell 11. That is, when the current breaker 11b is activated, the current path inside the unit cell 11 is cut off. For example, a fuse can be used as the current breaker 11b. By blowing the fuse, the current path inside the unit cell 11 can be interrupted.

  Moreover, the valve which deform | transforms according to the internal pressure of the cell 11 rises can be used as the current circuit breaker 11b, for example. The valve is deformed in response to an increase in the internal pressure of the unit cell 11, and the current path inside the unit cell 11 can be interrupted by breaking the mechanical connection with the power generation element 11a. The inside of the unit cell 11 is in a sealed state, and when gas is generated from the power generation element 11a, the internal pressure of the unit cell 11 increases. The mechanical connection with the power generation element 11a can be broken by deforming the valve as the current breaker 11b in response to the increase in the internal pressure of the unit cell 11. Thereby, it can block | prevent that charging / discharging electric current flows into the electric power generation element 11a, and can protect the cell 11 (electric power generation element 11a).

  Furthermore, as the current breaker 11b, for example, a PTC element whose resistance increases as the temperature rises can be used. The PTC element has a structure in which conductive particles such as carbon are solidified with an insulating resin, and when the temperature rises due to the flow of current, the insulating resin expands and the resistance increases. Can be cut off, and the current path inside the unit cell 11 can be cut off. Thereby, it can block | prevent that charging / discharging electric current flows into the electric power generation element 11a, and can protect the cell 11 (electric power generation element 11a).

  A system main relay 31 is provided on the positive electrode line PL of the assembled battery 10, and a system main relay 32 is provided on the negative electrode line NL of the assembled battery 10. The system main relays 31 and 32 are switched between on and off by receiving a control signal from the controller 50.

  When connecting the assembled battery 10 to a load, the controller 50 switches the system main relays 31 and 32 from off to on. Thereby, connection of the assembled battery 10 and load is completed, and the battery system shown in FIG. 1 will be in a starting state. On the other hand, when cutting off the connection between the assembled battery 10 and the load, the controller 50 switches the system main relays 31 and 32 from on to off. Thereby, the activation of the battery system shown in FIG. 1 is stopped.

  The booster circuit 41 boosts the output voltage of the assembled battery 10 and outputs the boosted power to the inverter 42. Further, the booster circuit 41 can step down the output voltage of the inverter 42 and output the lowered power to the assembled battery 10. The booster circuit 41 operates in response to a control signal from the controller 50. In the battery system of the present embodiment, the booster circuit 41 is used, but the booster circuit 41 may be omitted.

  The inverter 42 converts the DC power output from the booster circuit 41 into AC power and outputs the AC power to the motor generator 43. The inverter 42 converts the AC power generated by the motor / generator 43 into DC power and outputs the DC power to the booster circuit 41. As the motor generator 43, for example, a three-phase AC motor can be used.

  The motor / generator 43 receives AC power from the inverter 42 and generates kinetic energy for driving the vehicle or kinetic energy for cranking an engine (not shown). When the vehicle is driven using the electric power of the battery pack 10, the kinetic energy generated by the motor / generator 43 is transmitted to the wheels. When cranking the engine, the kinetic energy generated by the motor generator 43 is transmitted to the engine.

  When the vehicle is decelerated or stopped, the motor / generator 43 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 42 converts the AC power generated by the motor / generator 43 into DC power, and outputs the DC power to the booster circuit 32. The booster circuit 41 outputs the electric power from the inverter 42 to the assembled battery 10. Thereby, regenerative electric power can be stored in the assembled battery 10.

  The assembled battery 10 is provided with a voltage monitoring unit 20, a current sensor 21, and a temperature sensor 22. FIG. 3 is an example of a configuration block diagram of the battery system of the present embodiment.

  The voltage monitoring unit (corresponding to a voltage sensor) 20 detects a voltage between terminals of each unit cell 11 (referred to as a battery voltage), and outputs a detection result to the controller 50. In the present embodiment, the plurality of single cells 11 constituting the assembled battery 10 can be divided into a plurality of battery blocks. For example, the assembled battery 10 can be configured by dividing a plurality of single cells 11 connected in series into a plurality of battery blocks and connecting the divided battery blocks in series. In this case, the voltage monitoring unit 20 can detect the battery voltage in units of the single cells 11 and in units of the battery blocks. Further, the voltage monitoring unit 20 can detect the voltage between the terminals of the assembled battery 10.

  The current sensor 21 detects a current value (charge / discharge current value) flowing through the assembled battery 10 and outputs a detection result to the controller 50. The current value detected by the current sensor 21 when the battery pack 10 is discharged is set as a positive value, and the current value detected by the current sensor 21 when the battery pack 10 is charged is detected as a negative value. can do.

  The temperature sensor 22 detects the temperature (battery temperature) of each unit cell 11 and outputs the detection result to the controller 50. Note that the temperature sensor 22 can be configured to be included in the voltage monitoring unit 20, and can be configured as a monitoring IC that detects the voltage and temperature of the assembled battery 10, for example.

  The controller 50 functions as a control device that performs charge / discharge control of the assembled battery 10. The controller 50 performs discharge control for outputting the power of the assembled battery 10 to the load based on the output request, and charging control for charging the assembled battery 10 with regenerative power during vehicle braking when the vehicle decelerates or stops. It can be carried out.

  The controller 50 includes an abnormality detection unit 51 and a storage unit 52. The abnormality detection unit 51 performs processing for determining an abnormality of the single battery 11. The storage unit 52 stores a program for operating the controller 50 and specific information. Note that the processing performed by the abnormality detection unit 51 can be performed by a control device separate from the controller 50, and the storage unit 52 can be provided outside the controller 50.

  The auxiliary device 60 is a device (power consuming device) that is connected via the DC / DC converter 44 and operates by receiving power from the assembled battery 10. For example, an air conditioner, an AV device, and a lighting device mounted on a vehicle. A cooling device (for example, a cooling fan) for cooling the assembled battery 10. The electric power supplied from the assembled battery 10 to the auxiliary device 60 is controlled by the controller 50. The controller 50 performs charge / discharge control of the assembled battery 10 so as to supply power to the auxiliary device 60 according to the power consumption.

  Next, the battery abnormality determination process of the present embodiment will be described in detail. The current breaker 11b is activated, so that the current breaker 11b becomes conductive again due to physical contact, arc discharge, or the like even after the charge / discharge current is once blocked from flowing through the power generation element 11a. 11 may have a current flowing therethrough.

  The unit cell 11 in which the current breaker 11b is in a re-conducting state has an extremely increased resistance compared to a resistance increase such as deterioration. That is, the current breaker 11b acts as a resistor, and the unit cell 11 enters a high resistance state. When a voltage is applied to such a unit cell 11 and a current flows, the current breaker 11b in a high resistance state generates heat. For this reason, from the viewpoint of appropriately protecting the unit cell 11, it is necessary to promptly detect an abnormality of the unit cell 11 that has been re-conducted after the current breaker 11b is activated.

  While it is necessary to quickly detect the unit cell 11 that has been re-conducted after the current circuit breaker 11b is activated, the abnormality determination process for the unit cell 11 monitors the battery voltage and current value of the unit cell 11 to determine the current value. When the resistance indicating the amount of change in the voltage value with respect to the fluctuation is calculated, and the calculated resistance of the unit cell 11 is compared with a predetermined threshold, the calculated unit cell 11 has a resistance higher than the predetermined threshold. Abnormal resistance of the battery 11 can be detected.

  FIG. 4 is a diagram illustrating a method for calculating the resistance of the unit cell 11. As shown in FIG. 4, the resistance of the unit cell 11 can be calculated as a change amount of the voltage value with respect to the fluctuation of the current value. The resistance R1 of the unit cell 11 in which the current breaker 11b is not operated is calculated as a slope based on the relationship between the battery voltage and the current as represented by a solid line. In addition, the resistance R2 of the unit cell 11 that is re-conducted after the current breaker 11b is activated is also calculated as a slope based on the relationship between the battery voltage and the current, as indicated by a one-dot chain line. For example, when the battery voltage measured at time t1 is V1, the current value is I1, the battery voltage V2 measured at time t2 and the current value is I2, the resistance R of the cell 11 is R = (V2−V1). ) / (I2-I1).

  In this embodiment, since the resistance R2 of the unit cell 11 in which the current breaker 11b is in the re-conduction state is higher (steeply) than the resistance R1 of the normal unit cell 11, the change in voltage value with respect to the current value variation. The resistance R indicating the quantity is calculated, and the calculated resistance R of the unit cell 11 is compared with a predetermined threshold value corresponding to the resistance R1 of the normal unit cell 11, and the calculated resistance R of the unit cell 11 is predetermined. When the threshold value is higher than the threshold value, a resistance abnormality of the unit cell 11 is detected.

  However, the detection voltage of the voltage monitoring unit 20 and the detection current of the current sensor 21 each include a detection error. For this reason, in the state where the fluctuation of the current value is small, it is difficult to accurately detect the abnormality of the single cell 11 because the resistance R of the single cell 11 cannot be calculated with high accuracy. In particular, in a state where the charge / discharge current value is low (low rate region), the ratio of the detection error included in the detection current of the current sensor 21 increases, and the resistance R of the single battery 11 cannot be calculated accurately.

  FIG. 5 is a diagram showing the relationship between the resistance and current value of the unit cell 11 that is re-conductive after the current breaker 11b provided in the unit cell 11 is activated. The curve is based on the upper limit value of a predetermined calorific value obtained from the charge / discharge current value and the resistance value, and the charge / discharge current value and the resistance of the unit cell 11 in the state of re-conduction after the current breaker 11b is activated. Showing the relationship.

  As shown in FIG. 5, in the low rate region where the charge / discharge current value A <b> 1 or less, the ratio of the detection error included in the detection current of the current sensor 21 becomes large, and the resistance R of the unit cell 11 cannot be calculated accurately. Further, in the low-rate region indicated by hatching, the detection error of the voltage monitoring unit 20 is greatly affected in the region where the resistance of the unit cell 11 in which the current breaker 11b is activated (low-rate charge / discharge / low-resistance region). Thus, in the low rate charge / discharge / low resistance region where the influence of the detection error of the voltage monitoring unit 20 and the current sensor 21 is large, the resistance R of the unit cell 11 cannot be calculated with high accuracy.

  The low rate charge / discharge region can be set to be equal to or less than an abnormality detection allowable value corresponding to the detection error of the current sensor 21. For example, on the basis of the detection error of the current sensor 21 that can be acquired in advance, a value that can be permitted from the viewpoint of detection accuracy for the ratio that the detection current of the current sensor 21 includes the detection error can be determined as the abnormality detection allowable value. The same applies to the low resistance region, and the abnormality detection allowable value corresponding to the detection error of the current sensor 21 can be reduced. For example, based on the detection error of the voltage monitoring unit 20 that can be acquired in advance, an abnormality detection allowable value (for example, FIG. The resistance Ra) shown in FIG. Thus, the area below the abnormality detection allowable value of each of the voltage monitoring unit 20 and the current sensor 21 can be a low rate charge / discharge / low resistance area.

  Thus, if the detection accuracy of the resistance abnormality of the cell 11 decreases, it is not possible to quickly detect the abnormality of the cell 11 that is in a re-conductive state after the current breaker 11b is activated.

  Therefore, in this embodiment, the battery temperature of the unit cell 11 in the re-conduction state after the current breaker 11b is activated becomes higher than the battery temperature of the normal unit cell 11 where the current breaker 11b is not activated. By detecting this, the temporary abnormality determination is performed, and the abnormality of the single cell 11 is detected quickly and accurately by detecting the resistance abnormality of the single cell 11 by changing the power consumption of the auxiliary device 60 using the temporary abnormality determination as a trigger. Is detected.

  FIG. 6 is a diagram illustrating a temperature transition between the unit cell 11 (abnormal cell) and the normal unit cell 11 (normal cell) in a state in which the current breaker 11b is re-conductive after being activated. As shown in FIG. 6, the unit cell 11 that is in the re-conduction state after the current breaker 11 b is activated is in a high resistance state, and thus the temperature is extremely increased as compared with the normal unit cell 11. In this way, the temperature rise of the high-resistance cell 11 that is re-conductive after the current breaker 11b is activated is monitored in comparison with the battery temperature of the normal cell 11, and the temperature difference ΔT is determined by the current breaker 11b. When the cell 11 is in a re-conducting state after being activated and is higher than a predetermined value corresponding to the temperature rise, the cell 11 is determined as a temporary abnormality.

  FIG. 7 is a flowchart of the battery abnormality determination process of this embodiment. The battery abnormality determination process is performed by the controller 50. The controller 50 starts battery abnormality determination processing after the battery system is activated.

  In step 101, the controller 50 acquires the battery temperature of each unit cell 11 of the assembled battery 10 based on the output of the temperature sensor 22.

  In step S102, the controller 50 compares the battery temperature between the single cells 11 using the acquired battery temperature of each single cell 11, and determines whether or not the temperature difference is equal to or greater than a predetermined value. For example, in each unit cell 11 connected in series, the battery temperature between two adjacent unit cells 11 can be compared, or the battery temperatures of two arbitrary unit cells 11 can be compared. When it is determined that the temperature difference between the single cells 11 exceeds a predetermined value corresponding to the activation of the current breaker 11b, the controller 50 proceeds to step S103 and shifts the battery abnormality determination process to the temporary abnormality mode. When it is determined that the temperature difference between the single cells 11 does not exceed the predetermined value corresponding to the re-conduction after the current breaker 11b is activated, the controller 50 ends the battery abnormality determination process.

  In step S102, whether or not the temperature difference is equal to or greater than a predetermined value by comparing the battery temperatures between the two unit cells 11 for all the plurality of unit cells 11 connected in series constituting the battery pack 10. It can be configured to discriminate. At this time, when the battery temperature of at least one unit cell 11 is a battery temperature exceeding a predetermined value with respect to the battery temperature of the other unit cell 11, the battery abnormality determination process can be shifted to the temporary abnormality mode. .

  Further, in step S103, the controller 50 can set the input / output upper limit value of the charge / discharge control to be low by limiting the input / output power of the battery pack 10 with the transition to the temporary abnormality mode. For example, in the example of FIG. 5, the controller 50 starts charging / discharging from time t3 after it is determined that the temperature difference between the cells 11 exceeds a predetermined value corresponding to re-conduction after the current breaker 11b is activated. The upper limit value of the current value is set to an upper limit value lower than the upper limit value of the charge / discharge current before the transition to the temporary abnormality mode, and the controller 50 performs charge / discharge control based on the lower set upper limit value. By restricting the upper limit value to a lower value, it is possible to suppress the amount of heat generated by the unit cell 11 in the high resistance state in which the current breaker 11b is re-conductive after being activated.

  The controller 50 that has shifted to the temporary abnormality mode acquires the charge / discharge current value of the assembled battery 10 based on the output of the current sensor 21 in step S104. In step S105, the controller 50 determines whether or not the acquired charge / discharge current value is smaller than a predetermined value (abnormality determination allowable value), that is, whether or not the low-rate charge / discharge is being performed.

  When it is determined in step S105 that the low-rate charge / discharge is being performed, the controller 50 measures the duration of the low-rate charge / discharge when the charge / discharge current value is a predetermined value or less, and the duration of the low-rate charge / discharge is predetermined. It is determined whether or not the value is greater than or equal to the value. The controller 50 repeatedly performs step S106 to step S106, and when the low rate charge / discharge time continues for a predetermined time or longer, the controller 50 proceeds to step S107 and shifts to the low rate check mode. If it is determined in step S105 that the charge / discharge current value is larger than the predetermined value, the controller 50 shifts to a normal check mode, skips step S107, and proceeds to step S108.

  In step S107, the controller 50 performs power consumption fluctuation control that fluctuates the power consumption of the auxiliary device 60 as the low rate check mode, and the current value and voltage value of the unit cell 11 associated with the power consumption fluctuation control are determined by the voltage monitoring unit 20. And based on the output of the current sensor 21. In the power consumption fluctuation control, if the auxiliary device 60 is not operating, the power is consumed by controlling the auxiliary device 60 to operate, or the output value of the operating auxiliary device 60 is set higher or lower than the current state. Try to vary the power. Further, the power consumption fluctuation of the auxiliary device 60 in the low rate check mode can be performed at a constant cycle.

  FIG. 8 is a diagram illustrating an example of power consumption fluctuation control. For example, by operating an air conditioner mounted on a vehicle or increasing or decreasing the output value of an operating air conditioner at time t4, the assembled battery 10 Current fluctuation can be caused. At this time, the controller 50 varies the power consumption of the auxiliary device 60 so as to be equal to or greater than a predetermined current variation amount corresponding to the detection error of the voltage monitoring unit 20 and / or the current sensor 21. For example, the power consumption of the auxiliary device 60 can be varied so that the current value varies outside the detection error range of the current sensor 21.

  In step S108, the controller 50 calculates the resistance R of the unit cell 11 shown in FIG. 4 using the voltage value and the current value acquired during the power consumption fluctuation control in step S107. For example, in the example of FIG. 8, the resistance R of the unit cell 11 can be calculated using each voltage value and current value at time t4 and time t5. Further, when it is determined in step S105 that the charge / discharge current value is larger than the predetermined value, the abnormality detection unit 51 uses the voltage value and the current value during the charge / discharge control in step S108 to detect the resistance R of the single battery 11. Is calculated.

  In step S109, the controller 50 determines whether or not the resistance R calculated in step S108 is larger than a predetermined threshold corresponding to the operation of the current breaker 11b. When it is determined that the resistance R is greater than the predetermined value, the controller 50 proceeds to step S110 and detects a resistance abnormality of the unit cell 11, that is, an abnormality of the unit cell 11. When it is determined that the resistance R is smaller than the predetermined threshold, the battery abnormality determination process is terminated.

  In step S <b> 110, when the abnormality of the single battery 11 is detected, the controller 50 can limit the input / output of the assembled battery 10. As a method of limiting the input / output of the assembled battery 10, the upper limit power that allows the input / output of the assembled battery 10 can be reduced. The upper limit power is set for each of the input and output of the battery pack 10. Decreasing the upper limit power includes setting the upper limit power to 0 [kW]. By setting the upper limit power to 0 [kW], input / output of the assembled battery 10 is not performed.

  Further, when the unit cell 11 is in an abnormal state, the controller 50 can not resume charging / discharging of the assembled battery 10. Specifically, when it is determined that the unit cell 11 is in an abnormal state, the controller 50 can prevent the system main relays 31 and 32 from being switched from off to on.

  In step S108, the controller 50 can be configured to calculate resistance values of all the unit cells 11 constituting the assembled battery 10 and detect a resistance abnormality in step S109 for each unit cell 11. .

  Moreover, in step S102, the controller 50 compares the battery temperature between the single cells 11 using the acquired battery temperature of each single cell 11, and determines whether the temperature difference is equal to or greater than a predetermined value. Therefore, it is possible to identify the unit cell 11 having the higher battery temperature that is determined to have a temperature difference of a predetermined value or more. The controller 50 targets only the unit cell 11 having a higher battery temperature determined to have a temperature difference of a predetermined value or more, the voltage value and current value acquired during the power consumption fluctuation control in step S108, or the charge value. The resistance of the unit cell 11 can be calculated using the voltage value and the current value during the discharge control, and the resistance abnormality of the unit cell 11 can be determined in step S109.

  FIG. 7 shows an example of a mode in which power consumption fluctuation control is performed to vary the power consumption of the auxiliary device 60 as the low rate check mode when the charge / discharge current value in the low rate region continues for a predetermined time. Not only when the charge / discharge current value in the low rate region continues for a predetermined time, but the battery temperature between the single cells 11 is compared and it is determined that the temperature difference is greater than or equal to the predetermined value, and the temporary abnormal mode is entered in step S103. After the transition, steps S104 to S106 are omitted, and the process proceeds to step S107 to perform power consumption fluctuation control that fluctuates the power consumption of the auxiliary device 60, and the current value and voltage value of the unit cell 11 during the power consumption fluctuation control are obtained. It is also possible to configure to acquire based on the outputs of the voltage monitoring unit 20 and the current sensor 21.

  In the battery abnormality determination process of this embodiment, the temperature difference between the cells 11 is monitored to quickly detect the presence of the cells 11 that are re-conducted after the current breaker 11b is activated, and to force the auxiliary device 60. Since the resistance of the single battery 11 can be accurately detected by varying the power consumption of the single battery 11, the single battery 11 in which the current breaker 11b is in the re-conduction state can be detected quickly and accurately.

  In particular, since the resistance of the unit cell 11 is detected by forcibly changing the power consumption of the auxiliary device 60, the resistance of the unit cell 11 can be detected quickly and accurately even when charging and discharging at a low rate continues. be able to.

  Further, when the current breaker 11b is a valve that is deformed in response to an increase in the internal pressure of the unit cell 11, the valve is deformed in response to an increase in the internal pressure of the unit cell 11, and mechanically connected to the power generation element 11a. Is cut off, and the cell 11 in which the valve is activated is in an overcharged state. For this reason, when the recharging is continued from the overcharged state and the charging is further continued, the unit cell 11 cannot be properly protected. However, in the present embodiment, the unit cell 11 is accurately obtained even when the charge / discharge current value is at a low rate. Thus, the overcharged unit cell 11 in which the valve is operated can be appropriately protected.

(Example 2)
A battery system (corresponding to a power storage system) that is Embodiment 2 of the present invention will be described with reference to FIGS. The main configuration of the battery system of this example is the same as that shown in FIG. Hereinafter, the description will focus on the parts that are different from those of the first embodiment, and the same parts will be denoted by the same reference numerals and the description thereof will be omitted.

  In the present embodiment, the temperature increase of the unit cell 11 that is in the high resistance state after re-conducting after the operation of the current breaker 11b is accompanied by the increase in the internal resistance of the unit cell 11 (power generation element 11a) that is repeatedly charged and discharged. Since it is based on mechanical or physical heat generation different from the temperature rise, the temperature rise change amount and the temperature fall change amount per unit time are calculated, and the abnormal state of each unit cell 11 is determined.

  FIG. 9 is a diagram illustrating a temperature transition between the single battery 11 (abnormal battery) and the normal single battery 11 (normal battery) in a re-conduction state after the current breaker 11b is activated. In the normal cell 11 in which the current breaker 11b is not activated, the internal resistance of the power generation element 11a increases due to deterioration or the like, and the battery temperature rises as the internal resistance increases. It is a gradual increase according to the secular change due to the above, and the amount of change in the temperature increase is small. As shown in FIG. 9, ΔTa / Δt is the amount of change (rate of change) per unit time of the battery temperature that rises as the internal resistance of the unit cell 11 increases.

  On the other hand, since the unit cell 11 that is in the re-conduction state after the current breaker 11b is activated is in a high resistance state, the resistance of the unit cell 11 is extremely increased. For this reason, the rise in battery temperature accompanying the increase in resistance due to the operation of the current breaker 11b is based on mechanical or physical heat generation, and the amount of change in the temperature rise is the internal resistance of the cell 11. It is extremely larger than the amount of change per unit time of the battery temperature that rises with increasing. As shown in FIG. 9, the change in temperature rise per unit time of the unit cell 11 in the re-conduction state after the current breaker 11b is activated is ΔT1 / Δt, which is larger than ΔTa / Δt. .

  On the other hand, the increase in temperature of the unit cell 11 in the re-conduction state after the current breaker 11b is activated is based on mechanical or physical heat generation, so that the amount of change in which the temperature decreases due to cooling (temperature change amount). Is also big. That is, since the current breaker 11b generates surface heat as a resistor, the amount of temperature decrease per unit time is larger than when the battery temperature that rises as the internal resistance of the unit cell 11 increases is cooled. . The battery temperature that rises with an increase in the internal resistance of the unit cell 11 is the heat generation of the power generation element 11a generated from the inside of the unit cell 11, so that the amount of temperature decrease per unit time is smaller than the surface heat generation. As shown in FIG. 9, the change in temperature drop per unit time of the unit cell 11 in the re-conduction state after the current breaker 11b is activated is ΔT2 / Δt, and the single unit in which the current breaker 11b is not activated. The temperature change amount of the battery 11 is smaller than ΔT2 / Δt.

  In the present embodiment, the difference in temperature rise tendency and temperature fall tendency between the unit cell 11 in the re-conduction state after the current breaker 11b is activated and the unit cell 11 in which the current breaker 11b is not activated. Based on this, the unit cell 11 which is re-conducted after the current breaker 11b is activated is detected quickly and accurately.

  FIG. 10 is a configuration block diagram of the battery system of the present embodiment. A cooling device 70 is provided with respect to the diagram shown in FIG. The cooling device 70 is a blower such as a cooling fan, and the drive control of the cooling device 70 is performed by the controller 50. The controller 50 drives the cooling device 70 according to the battery temperature of the assembled battery 10 detected by the temperature sensor 22 to cool the assembled battery 10.

  FIG. 11 is a flowchart of the battery abnormality determination process of this embodiment. The battery abnormality determination process is performed by the controller 50. The controller 50 starts battery abnormality determination processing after the battery system is activated.

  In step 301, the controller 50 acquires the charge / discharge current value of the assembled battery 10 based on the output of the current sensor 21. In step S302, the controller 50 determines whether or not the acquired charge / discharge current value is smaller than a predetermined value (an abnormality determination allowable value corresponding to the detection error of the current sensor 21 similar to that in the first embodiment), that is, a low rate. It is determined whether or not charging / discharging is in progress.

  When it is determined in step S302 that the charge / discharge current value is larger than the predetermined value, the controller 50 performs steps S309 and S310, and the abnormality based on the resistance of the unit cell 11 shown in FIG. Judgment processing is performed. Step S309 corresponds to step S108 in FIG. 7, and step S310 corresponds to step S109 in FIG.

  In step S <b> 302, when it is determined that the charge / discharge current value is smaller than the predetermined value, the controller 50 acquires the battery temperature of each unit cell 11 of the assembled battery 10 based on the output of the temperature sensor 22.

  In step S304, the controller 50 calculates the temperature increase change amount per unit time of each unit cell 11 based on the acquired detected temperature of each unit cell 11, and each temperature increase change calculated between the unit cells 11 is calculated. It is determined whether or not the amount difference is equal to or greater than a predetermined value corresponding to re-conduction after the current breaker 11b is activated. For example, in each unit cell 11 connected in series, the temperature increase change amount between two adjacent unit cells 11 can be compared, or the temperature increase change amount of any two unit cells 11 can be compared.

  In step S304, the predetermined value (corresponding to the first threshold value) to be compared with the difference between the temperature change amounts calculated between the single cells 11 is that the normal single cell 11 in which the current breaker 11b is not operating is The temperature can be determined in consideration of the temperature corresponding to the amount of heat calculated from a predetermined resistance (deterioration upper limit resistance value) that is determined to be abnormal due to an increase in the internal resistance of the power generation element 11a due to deterioration or the like. That is, the predetermined value may be a value larger than the temperature increase change amount in the temperature rise according to the heat generation amount calculated from the deterioration upper limit resistance value of the normal unit cell 11 in which the current breaker 11b is not operating. And a temperature rise change amount due to an increase in internal resistance of the power generation element 11a due to deterioration or the like, and a temperature rise change amount due to a temperature rise of the unit cell 11 in the re-conduction state after the current breaker 11b is activated. Can be accurately determined.

  If the controller 50 determines that the difference in the temperature rise change amount between the cells 11 exceeds a predetermined value corresponding to the reconnection after the current breaker 11b is activated, the controller 50 proceeds to step S305 and determines whether the battery is abnormal. The process is shifted to the temporary abnormality mode. The controller 50 ends the battery abnormality determination process when it is determined that the difference in the temperature rise change amount between the single cells 11 does not exceed a predetermined value corresponding to the reconnection after the current breaker 11b is activated. To do.

  In step S304, whether or not the difference in the temperature rise change amount between the two single cells 11 is equal to or greater than a predetermined value for all the plurality of single cells 11 connected in series constituting the assembled battery 10 is determined. Determine. At this time, when the temperature rise change amount of at least one unit cell 11 exceeds a predetermined value corresponding to re-conduction after the current circuit breaker 11b is activated with respect to the temperature rise change amount of the other unit cell 11 The battery abnormality determination process can be shifted to the temporary abnormality mode.

  In step S306, the controller 50 that has shifted to the temporary abnormality mode drives the cooling device 70 to cool the assembled battery 10 and limits the input / output power of the assembled battery 10 to lower the input / output upper limit value of charge / discharge control. Set.

  For example, in the example of FIG. 9, the controller 50 determines that the difference in the temperature rise change amount between the single cells 11 exceeds a predetermined value corresponding to re-conduction after the current breaker 11b is activated. From time t6, the upper limit value of the charge / discharge current value is set to an upper limit value lower than the upper limit value of the charge / discharge current before the transition to the temporary abnormality mode, and charge / discharge control is performed based on the lower set upper limit value. By limiting the upper limit value low, it is possible to suppress the amount of heat generated by the high-resistance cell 11 that is re-conductive after the current breaker 11b is activated. Furthermore, the controller 50 drives the cooling device 70 from the time t7 after the elapse of a predetermined time from the time t6 to send cooling air to the assembled battery 10 to cool the assembled battery 10. At this time, the cooling device 70 can be driven with the drive output set to the maximum value.

  Thus, after it is determined that the difference in the temperature rise change amount between the single cells 11 exceeds a predetermined value corresponding to the re-conduction after the current breaker 11b is activated, the upper limit value is limited to a low value and the high resistance By cooling with the cooling device 70 while suppressing the heat generation amount of the unit cell 11 in the state, the battery temperature of the unit cell 11 in the re-conduction state after the current breaker 11b is activated can be reduced.

  Next, the controller 50 proceeds to step S307, and calculates a temperature drop change amount of each unit cell 11 to be cooled after the cooling device 70 is driven. As shown in FIG. 9, the temperature drop change amount ΔT2 / Δt per unit time is calculated from the time t7 when the cooling device 70 is driven. As in step S304, the controller 50 calculates each temperature increase change amount per unit time between the single cells 11, and the difference between the temperature change amounts calculated between the single cells 11 is determined after the current breaker 11b is activated. It is determined whether or not the value is equal to or greater than a predetermined value (corresponding to a second threshold) corresponding to the re-conduction. When the difference in the temperature drop change amount is larger than the predetermined value, the process proceeds to step S308, and abnormality of the single battery 11 is detected. When it is determined that the difference in temperature change amount is smaller than the predetermined value, the battery abnormality determination process is terminated.

  When an abnormality of the unit cell 11 is detected in step S308, the controller 50 limits the input / output of the assembled battery 10 or does not resume charging / discharging of the assembled battery 10 as in the first embodiment. It can be performed.

  In step S304, the controller 50 calculates the temperature increase change amount per unit time of each unit cell 11 based on the acquired detected temperature of each unit cell 11, and each increase calculated between the unit cells 11 is calculated. Since it is determined whether or not the difference in temperature change is greater than or equal to a predetermined value corresponding to the re-conduction after the current breaker 11b is activated, if there is a difference in temperature increase change amount greater than or equal to a predetermined value The unit cell 11 having the higher determined temperature change amount can be specified. The controller 50 can be configured to perform step S307 to determine abnormality of the unit cell 11 only for the unit cell 11 that is specified to have a temperature increase change amount higher than that of the normal unit cell 11. .

  In the example of FIG. 11, in the same manner as in the first embodiment, in view of the decrease in the detection accuracy of the resistance abnormality of the battery cell 11 in the low rate region below the predetermined charge / discharge current value, Although an example of performing the battery abnormality determination process is shown, the present invention is not limited to this, and the battery abnormality determination process of this embodiment can be performed by omitting steps S301 and S302.

  The battery abnormality determination process of the present embodiment is performed with respect to the temperature increase tendency and temperature decrease tendency of the unit cell 11 in the re-conduction state after the current breaker 11b is activated and the unit cell 11 where the current breaker 11b is not activated. Based on the difference, it is possible to accurately and quickly detect the unit cell 11 in the re-conduction state after the current breaker 11b is activated.

  In particular, since the resistance abnormality of the unit cell 11 is not detected based on the battery voltage or current value, it is possible to suppress a decrease in detection accuracy due to the detection error of the voltage monitoring unit 20 or the current sensor 21, and the low level described in the first embodiment. Even in the rate region and the low rate charge / discharge / low resistance region, it is possible to accurately detect the unit cell 11 in the re-conduction state after the current breaker 11b is activated.

  In addition, the battery abnormality determination process of this embodiment is based on the re-conduction state after the current breaker 11b is activated based on the difference in the temperature decrease tendency (temperature change amount) as well as the temperature increase tendency (temperature increase change amount). Since the unit cell 11 is detected, the normal cell unit 11b in which the current breaker 11b is not operating is associated with an increase in temperature due to an increase in internal resistance of the power generation element 11a due to deterioration or a decrease in cooling function. It is possible to detect the abnormality of the unit cell 11 in which the current breaker 11b is operated with high accuracy by reducing the influence of the temperature rise of the battery 10.

10 battery pack (power storage device)
11 Single cell (storage element)
11a Power generation element 11b Current breaker 20 Voltage monitoring unit 21 Current sensor 22 Temperature sensor 31, 32 System main relay 41 Booster circuit 42 Inverter 43 Motor generator 50 Controller 51 Abnormality detection unit 52 Storage unit 60 Auxiliary machine 70 Cooling device

Claims (7)

A power storage system mounted on a vehicle,
A power storage device in which a plurality of power storage elements each having a current breaker that interrupts a current path are connected in series;
A voltage sensor for detecting voltages of the plurality of power storage elements;
A current sensor for detecting a current flowing in the power storage device;
A temperature sensor for detecting temperatures of the plurality of power storage elements;
A controller for determining an abnormal state of the power storage element that is re-conductive after the current breaker is activated,
The controller is
When the temperature difference between the power storage elements is equal to or greater than a predetermined value, the power consumption of the power consuming device that operates by receiving power from the power storage device and is connected via a DC / DC converter is changed, and the power consumption Based on the voltage detected by the voltage sensor and the current detected by the current sensor due to power fluctuations, the resistance of the storage element indicating the amount of change in voltage relative to the amount of change in current is calculated, and the calculated resistance is higher than a threshold value Sometimes, the power storage system determines that the power storage element is in the abnormal state.   The controller varies power consumption of a power consuming device connected via the DC / DC converter when a detection current detected by the current sensor is equal to or less than an abnormality determination allowable value corresponding to a detection error of the current sensor. The power storage system according to claim 1.   The controller includes a power consuming device connected via the DC / DC converter when the current detected by the current sensor is a predetermined time or longer than the abnormality determination allowable value corresponding to the detection error of the current sensor. The power storage system according to claim 2, wherein the power consumption is fluctuated.   4. The controller according to claim 1, wherein when the temperature difference between the power storage elements is equal to or greater than a predetermined value, the controller sets the input / output upper limit value of charge / discharge control of the power storage device to be low. The electricity storage system described in 1. A power storage system mounted on a vehicle,
A power storage device in which a plurality of power storage elements each having a current breaker that interrupts a current path are connected in series;
A temperature sensor for detecting temperatures of the plurality of power storage elements;
A cooling device for cooling the power storage device;
A controller that calculates a temperature rise change amount and a temperature fall change amount per unit time of the power storage element based on a temperature detected by the temperature sensor, and determines an abnormal state of the power storage element that is re-conducted after the current breaker is activated. And having
The controller is
When the temperature increase change amount is equal to or greater than a first threshold value, the cooling device is driven, and when the temperature decrease change amount due to cooling of the power storage device by the cooling device is equal to or greater than a second threshold value, It is discriminated that the state is abnormal. A current sensor for detecting a current flowing through the power storage device;
When the current detected by the current sensor is equal to or less than an abnormality determination allowable value corresponding to the detection error of the current sensor, the controller determines an abnormal state of each power storage element based on the temperature increase change amount and the temperature decrease change amount. The power storage system according to claim 5, wherein discrimination is performed.   The power storage system according to claim 5 or 6, wherein the controller sets an input / output upper limit value of charge / discharge control of the power storage device to be low when the temperature increase change amount is equal to or greater than a first threshold value. .

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