JP5724940B2 - Power storage system and electrical component abnormality determination method - Google Patents

Description

  The present invention relates to a technique capable of determining an abnormal state due to heat generation in an electrical component in which a current flows along with charge / discharge of a power storage device.

  A current flows through the electrical component electrically connected to the secondary battery according to the charge / discharge of the secondary battery. When a current flows through the electrical component, the electrical component generates heat due to the resistance of the electrical component. Here, if the electric component generates excessive heat, the electric component may not operate normally, and thus it is necessary to suppress the heat generation of the electric component.

  In order to suppress excessive heat generation of the electrical component, an upper limit time during which the current can continue to flow through the electrical component may be set according to the current flowing through the electrical component. That is, the relationship between the current and the upper limit time may be set in advance. As a result, when a constant current is passed through the electrical component, the current can continue to flow through the electrical component within the range of the upper limit time corresponding to this current. Further, when the time during which the current continues to flow through the electrical component becomes longer than the upper limit time, it can be determined that the electrical component is in an abnormal state due to heat generation.

JP 2010-226894 A JP 2008-220088 A JP 2008-099449 A JP 2011-072133 A Japanese Patent Application Laid-Open No. 07-222370

  Depending on the charge / discharge of the secondary battery, the current flowing through the electrical component may change. If the current flowing through the electrical component changes, it becomes difficult to determine whether or not the electrical component is in an abnormal state due to heat generation, even if the relationship between the current and the upper limit time is used. That is, when a constant current is flowing through an electrical component, the upper limit time corresponding to this current can be specified, but if the current flowing through the electrical component changes, the upper limit time is specified from the changing current. It will be difficult.

The power storage system according to the first invention of the present application includes a power storage device that performs charging / discharging, an electrical component through which a current flows according to charging / discharging of the power storage device, a current sensor that detects a current flowing through the electrical component, and a heat generation of the electrical component And a controller for discriminating an abnormal state accompanying the. Here, the controller calculates the reciprocal corresponding to the current detected by the current sensor using the correspondence between the reciprocal of the upper limit time during which a current can continue to flow through the electric component and the current flowing through the electric component. The controller determines that the electrical component is in an abnormal state when the integrated value obtained by integrating the inverse every time the inverse is calculated is equal to or greater than a threshold value. At this time, the controller integrates a value larger than the reciprocal when the current detected by the current sensor is larger than the upper limit value.

According to the first invention of this application, by using the reciprocal number, it is possible to grasp the thermal influence caused by the current flowing through the electrical component every time the current flowing through the electrical component is detected. That is, it is possible to grasp the ratio of the current thermal influence to the thermal influence corresponding to the abnormal state. Then, each time the reciprocal is calculated, the thermal effects at different currents can be accumulated by accumulating the reciprocal. Thereby, even if the electric current which flows into an electrical component changes, it can discriminate | determine whether an electrical component is in an abnormal state by comparing an integrated value with a threshold value. Here, when the current detected by the current sensor is larger than the upper limit value, a value larger than the reciprocal can be integrated. That is, when calculating the integrated value, the reciprocal number is not integrated, but a value larger than the reciprocal number can be integrated. The greater the current flowing through the electrical component, the easier it is for the electrical component to reach an abnormal state.Accumulating a value larger than the reciprocal corresponding to the detected current makes it easier to increase the integrated value and the electrical component is in an abnormal state. It can be determined early.

  Regarding the relationship between the current flowing through the electrical component and the reciprocal, the reciprocal increases as the current flowing through the electrical component increases. In other words, the smaller the current flowing through the electrical component, the smaller the reciprocal. As the current flowing through the electrical component increases, even if the electrical component is dissipated, heat generation of the electrical component is less likely to be suppressed, and the electrical component is likely to reach an abnormal state. For this reason, the reciprocal increases as the current flowing through the electrical component increases. On the other hand, the smaller the current flowing through the electrical component, the more easily the heat generated by the electrical component is eliminated by heat dissipation, and the electrical component is less likely to reach an abnormal state. For this reason, the smaller the current flowing through the electrical component, the smaller the reciprocal.

  On the other hand, when the current detected by the current sensor is smaller than the lower limit value, the integrated value can not be increased. If the current flowing through the electrical component is small, even if the electrical component generates heat by energization, the heat generation of the electrical component can be eliminated by the heat dissipation of the electrical component. For this reason, it is not necessary to integrate the reciprocal corresponding to the detected current, and it is not necessary to increase the integrated value.

  Here, when the detected current is smaller than the lower limit value, a value of 0 or less can be integrated instead of the reciprocal. If the integrated value is 0, the integrated value will not increase or decrease. If the integrated value is a negative value, the integrated value will decrease. By subtracting the integrated value in accordance with the detected current, the integrated value can be made less likely to exceed the threshold value, and it is possible to prevent the electrical component from being easily determined to be in an abnormal state.

  The power storage system according to the first invention of the present application can be provided with a relay. When the relay is in the on state, the power storage device can be charged / discharged. When the relay is in the off state, the power storage device can be prevented from being charged / discharged. Here, when it is determined that the electrical component is in an abnormal state, the relay can be switched from the on state to the off state. Thereby, it is possible to prevent current from flowing through the electrical component, and it is possible to suppress heat generation of the electrical component. In addition, the electric component can be actively dissipated, and the electric component can be easily returned to the state before heat generation.

  The power storage system according to the first invention of the present application can be mounted on a vehicle. Here, the vehicle can be driven using the output of the power storage device.

A second invention of the present application is a method for determining an abnormal state accompanying heat generation of an electrical component through which a current flows in accordance with charge / discharge of a power storage device. First, using a current sensor, the current flowing through the electrical component is detected, and the detection by the current sensor is performed using the correspondence between the reciprocal of the upper limit time during which the current can continue to flow through the electrical component and the current flowing through the electrical component. The reciprocal corresponding to the current is calculated. When the integrated value obtained by integrating the inverse every time the inverse is calculated is equal to or greater than the threshold value, it is determined that the electrical component is in an abnormal state. At this time, the controller integrates a value larger than the reciprocal when the current detected by the current sensor is larger than the upper limit value. Also in the second invention of the present application, the same effect as that of the first invention of the present application can be obtained.

It is a figure which shows the structure of a battery system. It is a figure which shows the relationship between an electric current and protection time. It is a figure which shows the relationship between an electric current and an evaluation value. It is a flowchart which shows the process which discriminate | determines the abnormal state of an electrical component.

  Examples of the present invention will be described below.

  A battery system that is Embodiment 1 of the present invention will be described. FIG. 1 is a diagram showing the configuration of the battery system of this example. The battery system of the present embodiment can be 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 the vehicle.

  The assembled battery (corresponding to a power storage device) 10 includes a plurality of unit cells 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 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 are connected in series to form the assembled battery 10, but the assembled battery 10 may include a plurality of unit cells 11 connected in parallel. For example, the assembled battery 10 can be configured by preparing a plurality of battery blocks including a plurality of single cells 11 connected in series and connecting the plurality of battery blocks in parallel.

  A plug 12 is provided in the current path of the assembled battery 10. Specifically, the plug 12 is connected to the positive terminal of one unit cell 11 and the negative terminal of the other unit cell 11 out of the two unit cells 11 included in the assembled battery 10. The plug 12 constitutes a part of the current path in the assembled battery 10, and when the plug 12 is attached to the assembled battery 10, charge / discharge current flows through the assembled battery 10. On the other hand, when the plug 12 is removed from the assembled battery 10, the current path of the assembled battery 10 can be interrupted, and charging / discharging of the assembled battery 10 is not performed. The positions where the plugs 12 are provided and the number of plugs 12 can be set as appropriate.

  The assembled battery 10 has a fuse 13. The fuse 13 cuts off the current path of the assembled battery 10 by fusing when an excessive current flows through the assembled battery 10. Thereby, it can suppress that an excessive electric current flows into the assembled battery 10, and can protect the assembled battery 10. FIG. The position where the fuses 13 are provided and the number of the fuses 13 can be set as appropriate.

  The monitoring unit 21 detects the voltage between the terminals of the assembled battery 10 or detects the voltage between the terminals of the unit cell 11, and outputs the detection result to the controller 30. When the plurality of single cells 11 constituting the assembled battery 10 are divided into a plurality of battery blocks, the monitoring unit 21 can also detect the voltage between the terminals of each battery block. For example, each battery block can be configured by a plurality of single cells 11 connected in series, and the assembled battery 10 is configured by connecting a plurality of battery blocks in series.

  The current sensor 22 detects the current flowing through the assembled battery 10 and outputs the detection result to the controller 30. By using the current sensor 22, it is possible to detect a current flowing through the plug 12 and the fuse 13, and to detect a current flowing through lines (cables) PL and NL and a capacitor C described later.

  The assembled battery 10 is connected to the inverter 23 via a positive electrode line (cable) PL and a negative electrode line (cable) NL. A system main relay SMR-B is provided in the positive electrode line PL, and a system main relay SMR-G is provided in the negative electrode line NL. A system main relay SMR-P and a current limiting resistor R are connected in parallel to the system main relay SMR-G. Here, the system main relay SMR-P and the current limiting resistor R are connected in series.

  A capacitor C is connected to the positive electrode line PL and the negative electrode line NL. Specifically, the capacitor C is connected to a positive line PL that connects the system main relay SMR-B and the inverter 23 and a negative line NL that connects the system main relay SMR-G and the inverter 23. Capacitor C is used to smooth the voltage between positive line PL and negative line NL. Further, the current limiting resistor R is used for suppressing the inrush current from flowing through the load (for example, the capacitor C).

  System main relays SMR-B, SMR-G, and SMR-P are switched between ON and OFF in response to a control signal from controller 30. When connecting the assembled battery 10 to the inverter 23, the controller 30 first switches the system main relays SMR-B and SMR-P from off to on. Thereby, a current can be passed through the current limiting resistor R. Next, the controller 30 switches the system main relay SMR-P from on to off after switching the system main relay SMR-G from off to on.

  Thereby, the connection between the assembled battery 10 and the inverter 23 is completed, and the battery system shown in FIG. 1 is in a start-up state (Ready-On). On the other hand, when the activation of the battery system shown in FIG. 1 is stopped, the controller 30 switches the system main relays SMR-B and SMR-G from on to off. Thereby, the battery system shown in FIG. 1 is in a stopped state (Ready-Off).

  The inverter 23 converts the DC power output from the assembled battery 10 into AC power, and outputs the AC power to the motor generator (MG) 24. For example, a three-phase AC motor can be used as the motor / generator 24. The inverter 23 converts the AC power output from the motor / generator 24 into DC power, and outputs the DC power to the assembled battery 10.

  The motor / generator 24 receives AC power from the inverter 23 and generates kinetic energy for running the vehicle. The motor / generator 24 is connected to wheels, and the kinetic energy generated by the motor / generator 24 is transmitted to the wheels. Thereby, the vehicle can be driven.

  When the vehicle is decelerated or stopped, the motor generator 24 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The AC power generated by the motor / generator 24 is supplied to the assembled battery 10 via the inverter 23. Thereby, regenerative electric power can be stored in the assembled battery 10.

  The controller 30 includes a memory 31, and information for the controller 30 to execute a specific process is stored in the memory 31. In this embodiment, the memory 31 is built in the controller 30, but the memory 31 may be provided outside the controller 30.

  On the other hand, in the battery system of the present embodiment, the assembled battery 10 is connected to the inverter 23, but the present invention is not limited to this. Specifically, a boost converter can be provided in the current path between the assembled battery 10 and the inverter 23. If the boost converter is used, the output voltage of the battery pack 10 can be boosted and the boosted power can be output to the inverter 23. Further, by using the boost converter, it is possible to step down the output voltage of the inverter 23 and output the stepped down power to the assembled battery 10.

  In the battery system of the present embodiment, a system for supplying power from an external power source to the assembled battery 10 can be added. The external power source is a power source provided separately from the battery system outside the battery system. For example, a commercial power source can be used as the external power source. The assembled battery 10 can be charged by supplying power from the external power source to the assembled battery 10.

  When the external power supply supplies AC power, it is necessary to provide a charger for converting AC power into DC power. The charger can be added to the battery system shown in FIG. 1 or can be provided outside the battery system separately from the battery system. Further, when power from an external power source is supplied to the assembled battery 10, the voltage can also be converted.

  On the other hand, in the battery system of the present embodiment, a system for supplying the power of the assembled battery 10 to an external device can be added. The external device is an electronic device provided separately from the battery system outside the battery system. As the external device, for example, a home appliance can be used. By supplying the power of the assembled battery 10 to the external device, the external device can be operated.

  In the electric parts used in the battery system of the present embodiment, a current flows according to charging / discharging of the assembled battery 10. The electrical component is an electrical component provided in a current path when charging / discharging the assembled battery 10. In the present embodiment, examples of the electrical components include a plug 12, a fuse 13, lines (cables) PL and NL, system main relays SMR-B, SMR-G, SMR-P, and a capacitor C. In addition, an electrical component is not restricted to the component mentioned above, What is necessary is just to be provided in the electric current path | route when charging / discharging the assembled battery 10, and an electric current flows according to charging / discharging of the assembled battery 10. FIG.

  When a current flows through the electrical component, the electrical component generates heat due to the resistance of the electrical component. Since the heat generation amount is proportional to the product of the resistance of the electrical component and the value obtained by squaring the current, the heat generation amount of the electrical component increases as the current increases. If an electrical component generates excessive heat, the electrical component may not operate normally. Therefore, the amount of heat generated by the electrical component must be less than or equal to the upper limit of the amount of heat that allows the electrical component to operate normally. There is.

  Here, for each electrical component, as shown in FIG. 2 (an example), an upper limit value for protecting each electrical component can be set in advance. In FIG. 2, the horizontal axis represents the current flowing through the electrical component, and the current increases as it proceeds to the right side of FIG. 2. Also, the vertical axis represents the protection time, and the protection time becomes longer as it goes upward in FIG. The protection time is the upper limit of the continuous energization time that allows the electrical component to operate normally when a current continues to flow through the electrical component. As shown in FIG. 2, the protection time can be set according to the current flowing through the electrical component. Here, the graph shown in FIG. 2 is represented as a semilogarithmic graph.

  As shown in FIG. 2, the protection time is shortened as the current increases. In other words, the protection time increases as the current decreases. As the current flowing through the electrical component increases, the amount of heat generated by the electrical component increases. Therefore, in order to protect the electrical component from excessive heat generation, it is necessary to shorten the protection time of the electrical component. On the other hand, the smaller the current flowing through the electrical component, the smaller the amount of heat generated by the electrical component, and the more the heat generated by the electrical component can be suppressed by the heat dissipation of the electrical component. In this case, the protection time of the electrical parts can be extended.

  In the present embodiment, the graph shown in FIG. 3 is created in advance based on the graph shown in FIG. The graph shown in FIG. 3 is also created for each electrical component. In FIG. 3, the horizontal axis represents the current flowing through the electrical component, and the current increases as it proceeds to the right side of FIG. 3. The vertical axis represents the evaluation value k, and the evaluation value k increases as the value moves upward in FIG. The evaluation value k is the reciprocal of the protection time shown in FIG. 2, and is used to determine an abnormal state accompanying the heat generation of the electrical component, as will be described later.

  In the present embodiment, the evaluation value k is the reciprocal of the protection time in the region where the current is equal to or greater than Imin. That is, in the region where the current is equal to or greater than Imin, the evaluation value k can be calculated based on the protection time shown in FIG. On the other hand, as shown in FIG. 3, the evaluation value k is a negative value smaller than 0 in the region where the current is smaller than Imin. In this embodiment, by setting a current range in which the evaluation value k is smaller than 0, as will be described later, it becomes easier to determine that the electrical component is in an abnormal state in the determination of the abnormality of the electrical component. I try to suppress it.

  The specific value of the current Imin can be appropriately set based on the viewpoint of determining the abnormal state of the electrical component. Here, the current Imin may not be set. That is, the reciprocal of the protection time shown in FIG. 2 can be used as the evaluation value k in the entire current range. Information regarding the graph shown in FIG. 3 can be prepared in advance for each electrical component and stored in the memory 31. Further, the current range shown in FIG. 3 only needs to include the upper limit value and the lower limit value of the current that can be taken when the battery pack 10 is charged and discharged.

  Next, processing for determining an abnormal state of an electrical component will be described using the flowchart shown in FIG. The process shown in FIG. 4 is executed by the controller 30 in a predetermined cycle (for example, 1 second). Further, while the assembled battery 10 is being charged / discharged, specifically, while the assembled battery 10 is connected to the inverter 23, the process shown in FIG.

  In step S <b> 101, the controller 30 acquires the current flowing through the electrical component based on the output of the current sensor 22. Here, the direction of the current flowing through the electrical component changes according to the charging and discharging of the battery pack 10, but if the current flows through the electrical component, the electrical component will generate heat. It is sufficient that the magnitude of the current flowing through the electrical component can be acquired.

  In the battery system shown in FIG. 1, since the assembled battery 10 (or the single battery 11) and the electrical components are connected in series, the current flowing through the assembled battery 10 is equal to the current flowing through each electrical component. For this reason, the current detected by the current sensor 22 becomes the current flowing through each electrical component.

  In the assembled battery 10, when a plurality of battery blocks are connected in parallel and each battery block is configured by a plurality of single cells 11 connected in series, the current flowing through the electrical component is determined by the current sensor 22. The detected value can be used as it is, or a value after a predetermined calculation process is performed on the current detected by the current sensor 22 can be used. Since the current sensor 22 is provided outside the assembled battery 10, when the assembled battery 10 is configured by connecting a plurality of battery blocks in parallel, the current flowing through each battery block cannot be acquired. For example, when the plug 12 and the fuse 13 are provided for each battery block, the current flowing through the plug 12 and the fuse 13 cannot be acquired.

  Therefore, on the assumption that the internal resistances of the plurality of battery blocks constituting the assembled battery 10 are equal, the current flowing through each battery block is obtained by dividing the current detected by the current sensor 22 by the number of battery blocks. Can do. It is possible to acquire the current that flows through the electrical components provided in each battery block. In addition, if the current sensor 22 is provided for each battery block, the current flowing through the electrical components provided in each battery block can be acquired based on the output of the current sensor 22. Here, by providing one current sensor 22 for the assembled battery 10 as in the present embodiment, the number of current sensors 22 can be reduced, and the cost can be reduced.

  In step S102, the controller 30 calculates the evaluation value k_now of the electrical component based on the current acquired in the process of step S101. Specifically, the controller 30 specifies the evaluation value k_now corresponding to the current acquired in step S101, using the graph shown in FIG. 3 provided corresponding to each electrical component. In this embodiment, the evaluation value k_now is specified using the graph shown in FIG. 3, but the present invention is not limited to this. For example, the evaluation value k_now can be calculated by preparing an arithmetic expression corresponding to the graph shown in FIG. 3 and substituting the current into the arithmetic expression.

  In step S103, the controller 30 calculates an integrated value Σk that is a value obtained by integrating the evaluation values k. When calculating the integrated value Σk, the evaluation value k_now calculated this time in the process of step S102 is added to the previous integrated value Σk_old. Here, when the evaluation value k_now is calculated for the first time, 0 can be used as the integrated value Σk_old. The controller 30 stores the integrated value Σk calculated in the process of step S103 in the memory 31. The integrated value Σk stored in the memory 31 is used when calculating the integrated value Σk in the next processing.

  When the current acquired in the process of step S101 is smaller than Imin (see FIG. 3), the evaluation value k is a negative value, so the integrated value Σk is smaller than the previous integrated value Σk_old. That is, when the evaluation value k is a negative value, the integrated value Σk decreases without increasing. When the current flowing through the electrical component is smaller than Imin, the electrical component generates heat due to the current flowing through the electrical component, but the heat generation of the electrical component is eliminated by the heat dissipation of the electrical component exceeding the heat generation.

  As will be described later, the integrated value Σk is used to determine an abnormal state of the electrical component due to heat generation, but it is not necessary to increase the integrated value Σk when the heat generation of the electrical component is resolved. Further, if the integrated value Σk is increased even though the heat generation of the electrical component has been eliminated, it is easy to determine that the electrical component is in an abnormal state.

  For this reason, when the current is smaller than Imin, in other words, in a state where the heat generation of the electrical component is eliminated by heat dissipation, the evaluation value k can be set to 0 or less. Here, in this embodiment, when the current is smaller than Imin, the evaluation value k is a negative value. By using a negative value as the evaluation value k, an increase in the integrated value Σk is suppressed to prevent the electrical component from being easily determined to be in an abnormal state. Note that the evaluation value k may be set to 0 when the integrated value Σk is neither increased nor decreased when the current is smaller than Imin.

  Here, Imin may be a fixed value, or Imin may be changed based on a parameter that affects the heat dissipation of the electrical component. As a parameter that affects the heat dissipation of the electrical component, for example, a temperature around the electrical component (for example, an outside air temperature) can be used.

  When the temperature around the electrical component becomes high, it becomes difficult for the electrical component to dissipate heat and it becomes difficult to eliminate the heat generated by the electrical component. For this reason, Imin can be brought closer to 0 as the temperature around the electrical component increases. As Imin is decreased, the evaluation value k is less likely to be 0 or less, and the integrated value Σk is likely to increase. That is, since the electrical component is difficult to dissipate heat, the integrated value Σk increases.

  On the other hand, the larger the current flowing through the electrical component, the more the heat dissipation of the electrical component can be ignored. That is, when an excessive current flows through the electrical component, even if the electrical component dissipates heat, the amount of heat generated by the electrical component tends to increase, and the electrical component easily reaches an abnormal state. Considering this point, when the current flowing through the electrical component is larger than a predetermined upper limit value, the evaluation value k can be made larger than the reciprocal of the protection time shown in FIG.

  By making the evaluation value k larger than the reciprocal of the protection time, the integrated value Σk can be easily increased, and it can be determined early that the electrical component has reached an abnormal state. When the evaluation value k is larger than the reciprocal of the protection time, the difference between the reciprocal of the protection time and the evaluation value k can be set as appropriate. For example, the difference can be increased as the current flowing through the electrical component increases. When the current flowing through the electrical component is larger than Imin and smaller than the upper limit value, as described above, the reciprocal of the protection time shown in FIG. 2 can be used as the evaluation value k.

  While the battery pack 10 is being charged / discharged, current flows through the electrical component, so that the evaluation value k corresponding to the current flowing through the electrical component is integrated. By continuing to integrate the evaluation value k, the integrated value Σk approaches 1. Here, when the integrated value Σk is 1, the time when a specific current continues to flow through the electrical component is the same as when the protection time shown in FIG. 2 is reached (that is, an abnormal state). For example, when a current corresponding to a protection time of 100 seconds is continuously supplied to an electrical component, the evaluation value k obtained in each process shown in FIG. 4 becomes 1/100, and if the evaluation value k is integrated 100 times, in other words When 100 seconds elapse, the integrated value Σk becomes 1.

  In step S104, the controller 30 determines whether or not the integrated value Σk is equal to or greater than a threshold value. Here, when the integrated value Σk is 1, since the electrical component has reached an abnormal state as described above, 1 can be used as the threshold value. However, a value other than 1 can be used as the threshold value. Considering that the evaluation value k may deviate from the actual heat generation state of the electrical component, the threshold value may be set to a value larger than 1 or a value smaller than 1. it can. However, it is preferable that the threshold value is not greatly shifted with respect to 1. Information about the threshold value can be stored in the memory 31.

  In the process of step S104, when the integrated value Σk is equal to or greater than the threshold value, the process proceeds to step S105, and when the integrated value Σk is smaller than the threshold value, the process shown in FIG. When the integrated value Σk is equal to or greater than the threshold value, it can be determined that the electrical component is in an abnormal state due to heat generation.

  In step S105, the controller 30 switches the system main relays SMR-B and SMR-G from on to off. When the electrical component is in an abnormal state, it is necessary to cut off the energization to the electrical component in order to suppress further heat generation of the electrical component. By switching the system main relays SMR-B and SMR-G from on to off, charging / discharging of the assembled battery 10 is not performed, and energization of the electrical components can be cut off.

  According to the present embodiment, when it is determined that any one of the plurality of electrical components is in an abnormal state, the system main relays SMR-B and SMR-G are switched from on to off. Thereby, it is possible to protect the electrical component that has reached the abnormal state earliest.

  In the system that supplies power from the external power source to the assembled battery 10, the assembled battery 10 and the external power source can be connected via the system main relays SMR-B, SMR-G, and SMR-P. In this case, it is possible to determine whether or not the electrical component is in an abnormal state when power from the external power source is supplied to the assembled battery 10. That is, the current flowing through the electrical component is acquired to obtain the integrated value Σk, and it can be determined whether or not the integrated value Σk is equal to or greater than a threshold value.

  On the other hand, in the system that supplies the power of the assembled battery 10 to an external device, the assembled battery 10 and the external device can be connected via the system main relays SMR-B, SMR-G, and SMR-P. In this case, when the electric power of the assembled battery 10 is supplied to the external device, it can be determined whether or not the electrical component is in an abnormal state. That is, the current flowing through the electrical component is acquired to obtain the integrated value Σk, and it can be determined whether or not the integrated value Σk is equal to or greater than a threshold value.

  Even in a system that supplies power from an external power source to the assembled battery 10 or a system that supplies power from the assembled battery 10 to an external device, when it is determined that the electrical component is in an abnormal state, The main relays SMR-B and SMR-G can be switched from on to off. Thereby, it can interrupt that an electric current flows into an electrical component, and can protect an electrical component.

  System main relay SMR-B. When the SMR-G is switched from on to off, the electric power of the assembled battery 10 cannot be supplied to the motor / generator 24, and the vehicle cannot be driven using the output of the assembled battery 10. Here, in the hybrid vehicle, the vehicle can continue to travel by using a power source (for example, an engine or a fuel cell) other than the assembled battery 10.

  In this embodiment, the user can be warned when the integrated value Σk approaches the threshold value. As described above, when the integrated value Σk is equal to or greater than the threshold value, the system main relays SMR-B and SMR-G are switched from on to off, so that it is possible to notify the user in advance that such a state will occur. it can. The content of the warning to the user can be set as appropriate. Moreover, a sound or a display can be used as a warning method for the user. For example, it is possible to warn the user using acoustic equipment mounted on the vehicle, or to warn the user by displaying specific information on a display mounted on the vehicle.

  When the current flowing through the electrical component is constant, it is easy to determine the abnormal state of the electrical component using the map shown in FIG. That is, when the current continues to flow through the electrical component for the protection time corresponding to the current flowing through the electrical component, it can be determined that the electrical component is in an abnormal state. On the other hand, when charging / discharging the assembled battery 10, the current detected by the current sensor 22, that is, the current flowing through the electrical component changes according to the traveling pattern of the vehicle.

  In a situation where the current flowing through the electrical component is likely to change, it is difficult to determine the abnormal state of the electrical component even using the map shown in FIG. That is, according to the time, the current flowing through the electrical component changes and the protection time also changes. Therefore, it is difficult to obtain information for determining whether or not the electrical component is in an abnormal state.

  According to the present embodiment, by using the reciprocal of the protection time as the evaluation value k, the thermal influence due to the current flowing in the electrical component is grasped in each discrimination cycle (cycle in which the processing shown in FIG. 4 is performed). be able to. That is, it is possible to grasp the ratio of the thermal influence due to the current flowing through the electrical component in the threshold. As shown in FIG. 2, when the current flowing through the electrical component is different, the time (protection time) until the electrical component is determined to be in an abnormal state is different. That is, the greater the current flowing through the electrical component, the greater the thermal effect on the threshold. In other words, the smaller the current flowing through the electrical component, the smaller the thermal effect on the threshold.

  If the evaluation value k, which is the reciprocal of the protection time, is used, the thermal influence on the threshold can be grasped according to the current value. Then, if the thermal influence (evaluation value k) occupying the threshold is integrated, it is easily determined whether or not the integrated value Σk has reached the threshold, in other words, whether or not the electrical component has reached an abnormal state. can do. Thus, even if the current flowing through the electrical component changes, it is possible to determine whether or not the electrical component is in an abnormal state by accumulating the evaluation value k.

  Further, according to the present embodiment, it is possible to determine whether or not the electrical component is in an abnormal state using only the detection result of the current sensor 22, and the abnormal state determination processing can be easily performed.

  Note that after the system main relays SMR-B and SMR-G are switched from on to off and no current flows through the electrical components, the temperature of the electrical components decreases due to heat dissipation of the electrical components. The longer the time during which no current flows through the electrical component, the easier it is for the electrical component to return to the state before heat generation. For this reason, the time during which no current flows through the electrical components, in other words, the time during which the system main relays SMR-B, SMR-G, and SMR-P are off is measured. When it is longer than the time, it can be determined that the electrical component has returned to the state before heat generation. In this case, the integrated value Σk can be set to 0.

  Further, the integrated value Σk can be decreased according to the time during which no current flows through the electrical component. For example, the correspondence between the time during which no current flows through the electrical component and the amount of decrease in the integrated value Σk is determined in advance, and the integration is performed by the amount of decrease corresponding to the time during which no current flows through the electrical component. The value Σk can be decreased. Here, when the process shown in FIG. 4 is performed, the evaluation value k can be integrated based on the integrated value Σk after the decrease.

10: assembled battery, 11: single cell, 12: plug, 13: fuse, 21: monitoring unit,
22: current sensor, 23: inverter, 24: motor / generator,
30: Controller, 31: Memory, PL: Positive line, NL: Negative line,
SMR-B, SMR-G, SMR-P: System main relay,
R: current limiting resistor, C: capacitor

Claims (7)

A power storage device for charging and discharging; and
An electrical component through which a current flows according to charge and discharge of the power storage device;
A current sensor for detecting a current flowing through the electrical component;
A controller for determining an abnormal state associated with heat generation of the electrical component,
The controller is
The reciprocal corresponding to the current detected by the current sensor is calculated using the correspondence between the reciprocal of the upper limit time during which current can continue to flow through the electrical component and the current flowing through the electrical component, and the reciprocal is calculated. When the integrated value obtained by integrating the reciprocal every time is equal to or greater than a threshold, the electrical component is determined to be in the abnormal state ,
The power storage system , wherein the controller integrates a value larger than the reciprocal when the detected current is larger than an upper limit value .   The power storage system according to claim 1, wherein the reciprocal is larger as the current flowing through the electrical component is larger. Wherein the controller when the detected current is less than the lower limit, the power storage system according to claim 1 or 2, characterized in that does not increase the integrated value. The power storage system according to claim 3 , wherein the controller uses a value equal to or less than 0 instead of the reciprocal when the detected current is smaller than the lower limit value. And having a relay that switches between an on state for charging and discharging the power storage device and an off state for not charging and discharging the power storage device,
Wherein the controller, when the electrical component is determined to the the abnormal state, the power storage system according to claim 1, any one of 4, characterized in that switches the relay from the ON state to the OFF state . The power storage system according to any one of claims 1 to 5 , wherein the power storage device is mounted on a vehicle and outputs energy used for traveling of the vehicle. A method of determining an abnormal state associated with heat generation of an electrical component through which a current flows according to charge / discharge of a power storage device,
Using a current sensor, the current flowing through the electrical component is detected,
Using the reciprocal of the upper limit time during which current can continue to flow through the electrical component and the correspondence between the current flowing through the electrical component, the reciprocal corresponding to the current detected by the current sensor is calculated,
When the integrated value obtained by integrating the inverse every time the inverse is calculated is greater than or equal to a threshold, it is determined that the electrical component is in the abnormal state ;
When the detected current is larger than an upper limit value, a value larger than the reciprocal is integrated .

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