JP2016067077A - Electric power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine, when a current sensor is to detect the current value of a booster circuit, any trouble of fixation of the current value detected by the current sensor.SOLUTION: The ratio of the extent of variation of the voltage to that of variation of the current value is calculated and, if the difference between two ratios (k_last and k_now) calculated at different timings is within a prescribed range (a range less than K), the presence of trouble is determined. Before any trouble of a current sensor (24) occurs, the voltage and the current value vary, but once the current sensor runs into trouble, the current value becomes fixed though the voltage does vary. For this reason, the ratio is different after the current sensor runs into trouble from what it was before the current sensor ran into trouble. Therefore, if two ratios calculated at different timings are compared with the relation between the ratios before and after the occurrence of the current sensor trouble (the prescribed range) taken into consideration, it can be determined whether or not the current sensor has run into trouble.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage system that determines a failure of a current sensor that detects a current value of a booster circuit.

  In Patent Documents 1 and 2, etc., the output voltage of the battery is boosted using a booster circuit (converter). Here, when controlling the operation of the booster circuit, the current command value is set, and the operation of the booster circuit is controlled so that the current value of the booster circuit detected by the current sensor becomes the current command value. Here, in the systems shown in Patent Documents 1 and 2, the target current amount is calculated based on the difference between the target voltage value of the inverter calculated from the required torque of the vehicle and the voltage value of the inverter detected by the voltage sensor. can do. A current command value is set based on the target current amount.

JP 2009-213246 A JP 2013-024633 A

  The current sensor that detects the current value of the booster circuit may break down. Specifically, the current value detected by the current sensor (referred to as a detected current value) may be fixed to an arbitrary value even though the current value of the booster circuit is actually changing. In this case, if the operation of the booster circuit is controlled as described above, the actual current value of the booster circuit becomes too large or smaller than the current command value.

  Specifically, when the detected current value (fixed value) is smaller than the current command value, the current value flowing from the booster circuit to the inverter is increased by the control for correcting the difference between the detected current value and the current command value. Here, when the actual current value of the booster circuit is greater than or equal to the current command value, the actual current value of the booster circuit becomes too larger than the current command value by the control described above.

  On the other hand, when the detected current value (fixed value) is larger than the current command value, the current value flowing from the booster circuit to the inverter is reduced by the control for correcting the difference between the detected current value and the current command value. Here, when the actual current value of the booster circuit is equal to or less than the current command value, the actual current value of the booster circuit becomes too smaller than the current command value by the control described above.

  Thus, when the actual current value of the booster circuit fluctuates, a current containing a high frequency component flows to the battery, and the battery excessively generates heat. In order to suppress excessive heat generation of the battery, it is necessary to determine whether or not the above-described current sensor has failed.

  The power storage system according to the first invention of the present application includes a power storage device that performs charging and discharging, a booster circuit, a capacitor, a current sensor, a voltage sensor, and a controller. The booster circuit is connected to the power storage device via a positive electrode line and a negative electrode line, includes a reactor, and boosts the output voltage of the power storage device. The capacitor is connected to the positive electrode line and the negative electrode line described above. The current sensor detects the current value of the reactor. The voltage sensor detects a voltage value of the power storage device or the capacitor. The controller determines a failure (hereinafter simply referred to as a failure) in which the current value detected by the current sensor is fixed.

  The controller calculates a ratio indicating the ratio of the change amount of the voltage value to the change amount of the current value, and determines the occurrence of the failure when the value obtained by comparing the two ratios calculated at different timings is within a predetermined range. To do. The predetermined range is a range that can be taken by comparing the ratio when the current value and voltage value change with the predetermined ratio that defines the ratio when the voltage value changes and the current value does not change. It is.

  According to the first aspect of the present invention, it is possible to determine whether or not a failure has occurred in the current sensor by comparing two ratios calculated at different timings. The current value and the voltage value change before the failure of the current sensor. However, after the failure of the current sensor, the voltage value changes, but the current value is fixed. For this reason, the ratio is different between before the failure of the current sensor occurs and after the failure of the current sensor.

  Therefore, in consideration of the relationship between the ratios before and after the failure of the current sensor (predetermined range described above), if two ratios calculated at different timings are compared, whether or not the failure of the current sensor has occurred. Can be determined. Here, as a value obtained by comparing the two ratios, a ratio between the two ratios or a difference between the two ratios can be used.

  The power storage system according to the second invention of the present application includes a power storage device, a booster circuit, a capacitor, a current sensor, a voltage sensor, and a controller, as in the first invention of the present application. Here, every time the ratio is calculated, the controller determines whether or not the value obtained by comparing the two ratios calculated at different timings is within a predetermined range, and the value obtained by comparing the two ratios is within the predetermined range. While it is within, the count value is incremented. When the count value is larger than the predetermined value, the controller determines the occurrence of a failure.

  According to the second aspect of the present invention, the failure of the current sensor occurs not only when the value obtained by comparing the two ratios is within the predetermined range, but also when the count value is greater than the predetermined value. Is determined. Even if the failure of the current sensor does not occur, the value obtained by comparing the two ratios may temporarily fall within a predetermined range. On the other hand, if a failure occurs in the current sensor, the value obtained by comparing the two ratios remains within the predetermined range. Therefore, as in the second invention of the present application, when the count value is larger than the predetermined value, it is possible to suppress erroneous determination of the occurrence of the failure by determining that the failure of the current sensor has occurred. This makes it easier to determine the occurrence of a failure.

  The power storage system according to the third invention of the present application includes a power storage device, a booster circuit, a capacitor, a current sensor, a voltage sensor, and a controller, as in the first invention of the present application. The power storage system according to the third invention of the present application has a load connected to the booster circuit. Here, when the value obtained by comparing two ratios calculated at different timings is within a predetermined range, the controller changes the operating state of the load, and the difference between the current values before and after changing the operating state of the load is When the difference is less than or equal to the predetermined difference, the occurrence of a failure is determined.

  In the third invention of the present application, when the value obtained by comparing the two ratios is within a predetermined range, the current value is intentionally changed by changing the operating state of the load. As described above, even if the current sensor has not failed, the value obtained by comparing the two ratios may temporarily fall within a predetermined range. If the operating state of the load is changed and it is confirmed that the difference in current value is not more than a predetermined difference under the condition that the current value changes, it can be confirmed that the current value is fixed. As a result, it is possible to suppress erroneous determination of the occurrence of the failure of the current sensor, and it becomes easier to determine the occurrence of the failure.

  The power storage system according to the fourth invention of the present application includes a power storage device, a booster circuit, a capacitor, a current sensor, a voltage sensor, and a controller, as in the first invention of the present application. Here, the voltage sensor detects the voltage value of the capacitor. When a value obtained by comparing two ratios calculated at different timings is within a predetermined range, the controller determines whether the voltage value is within the predetermined voltage range, and the voltage value is within the predetermined voltage range. If it is, the occurrence of a failure is determined.

  In the fourth invention of the present application, it is determined that a failure of the current sensor has occurred not only when the value obtained by comparing the two ratios is within a predetermined range, but also when the voltage value is within the predetermined voltage range. doing. When only the capacitor is charged or discharged, the value obtained by comparing the two ratios may fall within a predetermined range.

  Here, when the power storage device and the capacitor are charged or discharged, the voltage value of the capacitor is within a predetermined voltage range, but when only the capacitor is charged or discharged, the voltage value of the capacitor is within the predetermined voltage range. Get out. Therefore, when the value obtained by comparing the two ratios is within a predetermined range, it is possible to prevent erroneous determination of the occurrence of a current sensor failure by confirming that the voltage value of the capacitor is within the predetermined voltage range. This makes it easier to determine the occurrence of a failure.

  When only the capacitor is charged or discharged, the current path for charging / discharging the power storage device is cut off in a state where charging / discharging of the capacitor is allowed. For this reason, when the voltage value of the capacitor is outside the predetermined voltage range, it can be determined that the above-described current path is interrupted.

It is a figure which shows the structure of a battery system. 5 is a flowchart illustrating processing for determining a failure of a current sensor in the first embodiment. It is a figure which shows the relationship between an electric current value and a voltage value. 10 is a flowchart illustrating processing for determining a failure of a current sensor in the second embodiment. 9 is a flowchart illustrating processing for determining a failure of a current sensor in Embodiment 3. It is an alignment chart which shows the relationship between the rotation speed of a motor generator and an engine. In Example 4, it is a flowchart which shows the process which discriminate | determines the failure of a current sensor. 14 is a flowchart illustrating processing for determining a failure of a current sensor in a modification of the fourth embodiment.

  Examples of the present invention will be described below.

  FIG. 1 shows the configuration of the battery system in this example. The battery system shown in FIG. 1 is mounted on a vehicle (a so-called hybrid vehicle). As will be described later, this vehicle includes an assembled battery and an engine as a power source for running the vehicle. Note that the present invention can also be applied to a vehicle (a so-called electric vehicle) that omits the engine and includes only the assembled battery as a power source.

  The assembled battery (corresponding to the power storage device of the present invention) 10 has a plurality of single cells. As the single battery, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor may be used instead of the secondary battery. The plurality of single cells included in the assembled battery 10 can be connected in series or in parallel.

  The voltage sensor 21 detects the voltage value VB of the assembled battery 10 and outputs the detection result to the controller 30. The current sensor 22 detects the current value IB of the assembled battery 10 and outputs the detection result to the controller 30. In this embodiment, the current value IB when the assembled battery 10 is discharged is a positive value, and the current value IB when the assembled battery 10 is charged is a negative value. The voltage value VB and the current value IB are used to control charging / discharging of the assembled battery 10.

  A positive electrode line PL is connected to the positive electrode terminal of the assembled battery 10, and a negative electrode line NL is connected to the negative electrode terminal of the assembled battery 10. The assembled battery 10 is connected to the booster circuit 40 via the positive electrode line PL and the negative electrode line NL. The system main relay SMR-B is provided in the positive line PL connecting the assembled battery 10 and the booster circuit 40, and the system main relay SMR-G is provided in the negative line NL connecting the assembled battery 10 and the booster circuit 40. It has been. A resistance element R and a system main relay SMR-P are connected in parallel to the system main relay SMR-G. Resistance element R and system main relay SMR-P are connected in series.

  System main relays SMR-B, SMR-G, and SMR-P receive a drive signal from controller 30 and are switched between on and off. A capacitor C is connected to the positive electrode line PL connecting the assembled battery 10 and the booster circuit 40 and the negative electrode line NL connecting the assembled battery 10 and the booster circuit 40. When the ignition switch of the vehicle is turned on, the controller 30 switches the system main relays SMR-B and SMR-P from off to on. Thereby, the capacitor C is charged by the discharge current of the assembled battery 10. At this time, the inrush current can be prevented from flowing through the capacitor C by causing the discharge current of the assembled battery 10 to flow through the resistance element R.

  After charging the capacitor C, the controller 30 switches the system main relay SMR-G from off to on and switches the system main relay SMR-P from on to off. Thereby, the battery system shown in FIG. 1 will be in a starting state (Ready-On). On the other hand, when the ignition switch is turned off, the controller 30 switches the system main relays SMR-B and SMR-G from on to off. As a result, the battery system shown in FIG. 1 enters a stopped state (Ready-Off).

  The voltage sensor 23 detects the voltage value VL of the capacitor C and outputs the detection result to the controller 30. A current sensor 24 is provided on the positive electrode line PL connecting the assembled battery 10 and the booster circuit 40. The current sensor 24 detects a current value IL of the booster circuit 40, that is, a current value IL flowing through a reactor 41 described later, and outputs a detection result to the controller 30. In this embodiment, the current value IL when the assembled battery 10 is discharged is a positive value, and the current value IL when the assembled battery 10 is charged is a negative value. As is well known, the current value IL is used to control the operation of the booster circuit 40. Here, detailed description of the control of the booster circuit 40 is omitted. The controller 30 has a memory 31, and predetermined information is stored in the memory 31.

  The booster circuit 40 is connected to the inverter 51 via the positive electrode line PL and the negative electrode line NL. The booster circuit 40 boosts the output voltage of the assembled battery 10 and outputs the boosted power to the inverter 51. The booster circuit 40 can step down the output voltage of the inverter 51 and output the stepped down power to the assembled battery 10. The booster circuit 40 operates in response to a control signal from the controller 30.

  The booster circuit 40 includes a reactor 41, diodes 42 and 43, and switching elements 44 and 45. One end of the reactor 41 is connected to the system main relay SMR-B, and the other end of the reactor 41 is connected to a connection point of the switching elements 44 and 45. The switching elements 44 and 45 are connected in series, and a control signal from the controller 30 is input to the bases of the switching elements 44 and 45. The switching elements 44 and 45 are switched between on and off in response to a control signal from the controller 30. Diodes 42 and 43 are connected between the collectors and emitters of the switching elements 44 and 45 so that current flows from the emitter side to the collector side.

  When the boosting operation of the booster circuit 40 is performed, the controller 30 turns on the switching element 45 and turns off the switching element 44. As a result, a current flows from the assembled battery 10 to the reactor 41, and magnetic energy corresponding to the amount of current is accumulated in the reactor 41. Next, the controller 30 causes the current to flow from the reactor 41 to the inverter 51 via the diode 42 by switching the switching element 45 from on to off. As a result, the energy accumulated in the reactor 41 is released, and the boosting operation is performed.

  When performing the step-down operation of the step-up circuit 40, the controller 30 turns on the switching element 44 and turns off the switching element 45. Thereby, the electric power from the inverter 51 is supplied to the assembled battery 10, and the assembled battery 10 is charged. Here, the step-down operation can be performed by flowing the current from the inverter 51 to the reactor 41.

  Inverter 51 converts the DC power output from booster circuit 40 into AC power, and outputs the AC power to motor generator MG2. Motor generator MG2 receives the AC power output from inverter 51 and generates power (kinetic energy). By transmitting the power generated by the motor / generator MG2 to the drive wheels 52, the vehicle can be driven.

  Motor generator MG2 converts kinetic energy generated during braking of the vehicle into AC power, and outputs the AC power to inverter 51. The inverter 51 converts AC power from the motor / generator MG <b> 2 into DC power and outputs the DC power to the assembled battery 10. Thereby, the assembled battery 10 can store regenerative electric power.

  The power split mechanism 53 transmits the power of the engine 54 to the drive wheels 52 or to the motor / generator MG1. Motor generator MG1 receives power from engine 54 to generate power. The AC power generated by the motor / generator MG1 is supplied to the motor / generator MG2 or the assembled battery 10 via the inverter 51.

  If the electric power generated by the motor / generator MG1 is supplied to the motor / generator MG2, the drive wheels 52 can be driven by the power generated by the motor / generator MG2. If the electric power generated by the motor generator MG1 is supplied to the assembled battery 10, the assembled battery 10 can be charged. On the other hand, the engine 54 can be cranked by supplying the electric power of the assembled battery 10 to the motor / generator MG1 and using the power generated by the motor / generator MG1.

  A DC / DC converter 55 is connected to positive line PL between system main relay SMR-B and booster circuit 40 and negative line NL between system main relay SMR-G and booster circuit 40. The DC / DC converter 55 steps down the output voltage of the assembled battery 10 and outputs the reduced power to the auxiliary device 56.

  In this embodiment, the failure of the current sensor 24 is determined. The failure of the current sensor 24 here is a failure in which the current value IL detected by the current sensor 24 is fixed to an arbitrary value, although the actual current value IL of the booster circuit 40 has changed.

  The process for determining the failure of the current sensor 24 will be described with reference to the flowchart shown in FIG. The process shown in FIG. 2 is executed by the controller 30. Further, the process shown in FIG. 2 is repeated at a predetermined cycle when the vehicle is running with the battery system activated.

  In step S <b> 101, the controller 30 detects the current value IL using the current sensor 24 a plurality of times for a predetermined time, and detects the voltage value VL using the voltage sensor 23. In step S102, the controller 30 calculates the ratio k_now based on the current value IL and the voltage value VL detected in the process of step S101, and stores the information of the ratio k_now in the memory 31.

  The ratio k_now is the ratio of the change amount of the voltage value VL to the change amount of the current value IL, as will be described later. Here, every time the ratio k_now is calculated by the process of step S102, the ratio k_now is stored in the memory 31, and the ratio k_now stored in the memory 31 is updated.

  A method for calculating the ratio k_now will be described with reference to FIG. FIG. 3 shows a coordinate system having the current value IL and the voltage value VL as coordinate axes. In this coordinate system, the relationship between the current value IL and the voltage value VL detected in the process of step S101 shown in FIG. 2 is plotted. Black circles shown in FIG. 3 indicate the relationship between the current value IL and the voltage value VL detected at different timings within a predetermined time. If a straight line L_now that approximates a plurality of plots is calculated, the slope of the straight line L_now becomes the ratio k_now.

  The slope of the straight line L_now is the ratio of the change amount of the voltage value VL to the change amount of the current value IL. If the current value IL changes, the voltage value VL changes along the straight line L_now. When current does not flow through reactor 41 and actual current value IL remains 0 [A], current value IL and voltage value VL do not change, and straight line L_now and ratio k_now cannot be calculated. Here, since the current value IL is likely to change during traveling of the vehicle in which the processing shown in FIG. 2 is performed, the straight line L_now and the ratio k_now can be calculated.

  In step S <b> 103 shown in FIG. 2, the controller 30 determines whether or not the ratio k_last is stored in the memory 31. The ratio k_last is the ratio k_now stored in the memory 31. As described above, every time the ratio k_now is calculated, the ratio k_now stored in the memory 31 is updated. Therefore, the ratio k_last is the most recently calculated ratio k_now. When the ratio k_last is not stored in the memory 31, the controller 30 ends the process shown in FIG. As a case where the ratio k_last is not stored in the memory 31, for example, the ratio k_now may be calculated for the first time. On the other hand, when the ratio k_last is stored in the memory 31, the controller 30 proceeds to the process of step S104.

  In step S104, the controller 30 determines whether or not a condition of the following formula (1) is satisfied.

  In the above equation (1), k_now is the ratio calculated in the process of step S102 when the process shown in FIG. 2 is performed this time. k_last is the ratio specified in the process of step S103. A value (k_last / k_now) obtained by dividing the ratio k_last by the ratio k_now is a value obtained by comparing the ratios k_last and k_now. In the determination by the above formula (1), it is determined whether or not the value obtained by dividing the ratio k_last by the ratio k_now is smaller than the constant K.

  The constant K is set in consideration of the ratio k_max that is the slope of the straight line L_max shown in FIG. The straight line L_max is a straight line (one example) showing the relationship between the current value IL and the voltage value VL when the current value IL does not change and the voltage value VL changes. As described above, when the current sensor 24 fails, the voltage value VL changes, but the current value IL is fixed to an arbitrary value. The relationship between the current value IL and the voltage value VL at this time is represented, for example, by a straight line L_max shown in FIG. The current value IL that defines the straight line L_max varies depending on the failure state of the current sensor 24.

  In the straight line L_max shown in FIG. 3, the ratio k_max becomes infinite, and in this embodiment, the ratio k_max is defined as a predetermined upper limit value (predetermined ratio). The constant K is a value obtained by comparing a predetermined ratio k_now when the current value IL is changing with a ratio k_max (the above-described upper limit value) when the current value IL is not changing. That is, the constant K is a value obtained by dividing the predetermined ratio k_now when the current value IL is changing by the ratio k_max (the above-described upper limit value) when the current value IL is not changing.

  Since the ratio k_max is higher than the predetermined ratio k_now when the current value IL is changing, the constant K is larger than 0 and smaller than 1. The constant K can be set in advance, and information on the constant K can be stored in the memory 31. The ratio k_now when the current value IL is changing may vary. At this time, the constant K can be set such that the range that can be taken by the value (k_now / k_max) obtained by dividing the ratio k_now by the ratio k_max is lower than the constant K (corresponding to the predetermined range of the present invention).

  When the current sensor 24 changes from the normal state to the failure state, the ratio k_now shown in FIG. 3 changes to the ratio k_max. In the process of step S104 illustrated in FIG. 2, such a change in the ratio is grasped by comparing the ratios k_last and k_now. That is, when the value of “k_last / k_now” is in a range lower than the constant K, it can be understood that the current sensor 24 has changed from the normal state to the failure state.

  In step S104 shown in FIG. 2, when the condition of the above formula (1) is not satisfied, the controller 30 ends the process shown in FIG. When the current sensor 24 has not failed, the ratio k_now may be lower than the ratio k_last or may be equal to or greater than the ratio k_last, but the value of “k_last / k_now” is equal to or greater than the constant K. For this reason, the condition of the above formula (1) is not satisfied, and the controller 30 can determine that the current sensor 24 has not failed.

  On the other hand, when the condition of the above formula (1) is satisfied, the controller 30 determines in step S105 that a failure of the current sensor 24 has occurred. Here, for example, the controller 30 sets a flag (referred to as a failure flag) indicating a failure of the current sensor 24. When the failure flag is set, the controller 30 can warn a user or the like. As a warning means, a known method can be appropriately employed. For example, a warning can be given by display on a display or generation of sound.

  According to the present embodiment, it is possible to determine whether or not a failure has occurred in the current sensor 24 by comparing the ratios k_last and k_now. Before the failure of the current sensor 24 occurs and after the failure of the current sensor 24, the ratio k_now changes abruptly as described with reference to FIG. In this embodiment, paying attention to this point, the ratios k_last and k_now are compared. If it is determined that a failure has occurred in the current sensor 24, charging / discharging of the assembled battery 10 can be stopped, and the assembled battery 10 can be prevented from excessively generating heat.

  In this embodiment, the ratio k_now is calculated based on the current value IL and the voltage value VL. However, the present invention is not limited to this. Specifically, when calculating the ratio k_now, the voltage value VB can be used instead of the voltage value VL. In this case, the ratio k_now is the ratio of the change amount of the voltage value VB to the change amount of the current value IL, and corresponds to the internal resistance value of the assembled battery 10.

  Here, as the deterioration of the assembled battery 10 progresses, the internal resistance value of the assembled battery 10 may increase, and the ratio k_now may increase. However, even if the internal resistance value of the battery pack 10 increases, the ratio k_now does not increase to the ratio k_max shown in FIG. As described above, the constant K is set in consideration of the ratio k_max, so that an increase in the internal resistance value of the assembled battery 10 and a failure of the current sensor 24 can be distinguished.

  Further, in this embodiment, in order to determine whether or not the failure of the current sensor 24 has occurred, it is determined whether or not the condition shown in the above equation (1) is satisfied. However, the present invention is not limited to this. Absent. That is, the ratios k_last and k_now are compared, and it is only necessary to determine whether or not a failure of the current sensor 24 has occurred based on the comparison result.

  For example, instead of the condition shown in the above formula (1), the condition shown in the following formula (2) can be set. When the ratios k_last and k_now are compared, the ratio k_now can be divided by the ratio k_last as shown in the following equation (2).

  The constant K ′ shown in the above equation (2) is set in consideration of the ratio k_max, like the constant K shown in the above equation (1). However, the constant K ′ is a value obtained by dividing the ratio k_max as a predetermined upper limit value by a predetermined ratio k_now when the current value IL is changing. Here, since the ratio k_max is higher than the predetermined ratio k_now, the constant K ′ is a value larger than 1. The ratio k_now when the current value IL is changing may vary. At this time, the constant K ′ is set so that the range (k_max / k_now) obtained by dividing the ratio k_max by the ratio k_now is higher than the constant K ′ (corresponding to the predetermined range of the present invention). it can. Thereby, when the value of “k_now / k_last” shown in the above equation (2) is in a range higher than the constant K ′, it can be understood that the current sensor 24 has changed from the normal state to the failure state.

  On the other hand, instead of the condition shown in the above formula (1), the condition shown in the following formula (3) can be set. When comparing the ratios k_last and k_now, the difference between the ratios k_last and k_now can be calculated as shown in the following equation (3).

  The constant K ″ shown in the above formula (3) is set in consideration of the ratio k_max, like the constant K shown in the above formula (1) and the constant K ′ shown in the above formula (2). The constant K ″ is a value (absolute value) obtained by subtracting a predetermined ratio k_now when the current value IL is changing from the ratio k_max. The ratio k_now when the current value IL is changing may vary. At this time, the constant K ″ is set so that the range in which the difference (absolute value) between the ratio k_now and the ratio k_max can be higher than the constant K ″ (corresponding to the predetermined range of the present invention). be able to. Accordingly, when the difference (absolute value) between the ratios k_now and k_max is in a range higher than the constant K ″, it can be grasped that the current sensor 24 has changed from the normal state to the failure state.

  Thus, in the present invention, in order to compare two ratios (ratio k_now, k_last) calculated at different timings, as shown in the above formula (1) or the above formula (2), the ratio k_now, When comparing the ratios k_now and k_last by calculating the ratio of k_last, and when comparing the ratios k_now and k_last by calculating the difference between the ratios k_now and k_last, as shown in the above equation (3). Is included.

  A second embodiment of the present invention will be described. In the present embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, differences from the first embodiment will be mainly described.

  In the first embodiment, it is determined that a failure has occurred in the current sensor 24 when the condition expressed by the above formula (1) is satisfied. In the present embodiment, it is determined that a failure has occurred in the current sensor 24 when the condition shown in the above equation (1) is satisfied a predetermined number of times. This process will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 4 corresponds to the flowchart shown in FIG.

  The process of step S201 is the same as the process of step S101. In step S202, the controller 30 calculates the ratio k_now based on the current value IL and the voltage value VL detected in the process of step S201. The method for calculating the ratio k_now is the same as the method described in the process of step S102 shown in FIG.

  In step S <b> 203, the controller 30 determines whether or not the ratio k_last is stored in the memory 31. When the ratio k_last is not stored in the memory 31, the controller 30 stores the information of the ratio k_now calculated in the process of step S202 in the memory 31 in step S204, and then ends the process illustrated in FIG. On the other hand, when the ratio k_last is stored in the memory 31, the controller 30 proceeds to the process of step S205. The process in step S205 is the same as the process in step S104 shown in FIG. Here, as described in the first embodiment, instead of determining whether or not the condition of the above expression (1) is satisfied, whether or not the condition shown in the above expression (2) or the above expression (3) is satisfied is determined. Can be determined.

  When the condition of the above formula (1) is satisfied in step S205, the controller 30 increments the count value c_kc in step S206. Here, the count value c_kc is 0 while the condition of the above expression (1) is not satisfied. Each time the process proceeds from step S205 to step S206, the count value c_kc is incremented. Information on the count value c_kc is stored in the memory 31.

  In step S207, the controller 30 determines whether or not the count value c_kc specified in the process of step S206 is larger than a predetermined value c_th. The predetermined value c_th is a value larger than 0, and can be set as appropriate. Information of the predetermined value c_th can be stored in the memory 31. When the count value c_kc is larger than the predetermined value c_th, the controller 30 proceeds to the process of step S208. The process in step S208 is the same as the process in step S105 shown in FIG.

  On the other hand, when the count value c_kc is equal to or smaller than the predetermined value c_th in step S207, the controller 30 ends the process shown in FIG. In step S205, when the condition shown in the above equation (1) is not satisfied, the controller 30 stores the information of the ratio k_now calculated in step S202 in the memory in step S209 and sets the count value c_kc. Reset.

  In the flowchart shown in FIG. 4, when the count value c_kc is incremented, the ratio k_now at this time is not stored in the memory 31. Therefore, the memory 31 stores the ratio k_now when the count value c_kc is “0”, in other words, the ratio k_now when the current sensor 24 is not broken down. This ratio k_now is used as the ratio k_last shown in the above equation (1) in the process of step S205.

  When the current sensor 24 is out of order, the ratio k_now remains the ratio k_max (see FIG. 3). As described above, since the ratio k_now when the current sensor 24 does not fail is used as the ratio k_last shown in the above expression (1), when the current sensor 24 has failed, The count condition c_kc continues to be incremented. When the count value c_kc is larger than the predetermined value c_th, it is determined that a failure of the current sensor 24 has occurred.

  In the processing of step S205, when the ratios k_last and k_now both indicate the ratio k_max, the value of “k_last / k_now” is 1 and is equal to or greater than the constant K, and therefore the condition shown in the above equation (1) is not satisfied. Become. Therefore, in this embodiment, in order to keep incrementing the count value c_kc when the current sensor 24 has failed, as described above, the ratio k_now when the current sensor 24 has not failed is expressed by the above equation (1). The ratio k_last shown in FIG.

  Depending on fluctuations in the power consumption of the auxiliary machine 56, the current value IL may not change and the voltage value VL may change even when the current sensor 24 has not failed. In this case, the ratios k_last and k_now temporarily satisfy the condition shown in the above equation (1). In consideration of this point, in this embodiment, it is determined that a failure of the current sensor 24 has occurred when the count value c_kc is larger than the predetermined value c_th. Thereby, it can suppress that the failure of the current sensor 24 has generate | occur | produced erroneously, and it becomes easy to confirm that the failure of the current sensor 24 has generate | occur | produced.

  Even if the ratio k_last, k_now temporarily satisfies the condition shown in the above expression (1), the ratio k_last, k_now no longer satisfies the condition shown in the above expression (1). In this case, the process proceeds from step S205 to step S209, and it is not determined that a failure of the current sensor 24 has occurred.

  A third embodiment of the present invention will be described. In the present embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, differences from the first embodiment will be mainly described.

  In this embodiment, the failure of the current sensor 24 is distinguished from the interruption of the current path in the positive line PL and the negative line NL. It is assumed that the current path is interrupted in the positive electrode line PL between the connection point of the capacitor C and the positive electrode line PL and the assembled battery 10. In this case, the positive electrode line PL may be disconnected. Further, it is conceivable that the system main relay SMR-B is turned off even though the system main relay SMR-B is driven on.

  When the battery system shown in FIG. 1 is in the activated state, as described above, if the current path in the positive electrode line PL is interrupted, the current value IL may not change and the voltage value VL may change. . For example, when the vehicle is traveling with power supplied to the motor / generator MG2, if the current path of the positive electrode line PL is interrupted, the assembled battery 10 is not discharged, and only the capacitor C is discharged. At this time, the current value IL may not change. In this case, the current value IL does not change and the voltage value VL decreases. Thereby, the relationship between the current value IL and the voltage value VL is represented by a straight line L_max shown in FIG.

  On the other hand, when the electric power generated by the motor / generator MG1 or the motor / generator MG2 is supplied to the assembled battery 10, if the current path of the positive line PL is interrupted, the assembled battery 10 cannot be charged, and only the capacitor C Is charged. At this time, the current value IL may not change. In this case, the current value IL does not change and the voltage value VL increases. Thereby, the relationship between the current value IL and the voltage value VL is represented by a straight line L_max shown in FIG.

  Even when the current path in the negative electrode line NL between the connection point of the capacitor C and the negative electrode line NL and the assembled battery 10 is interrupted, the relationship between the current value IL and the voltage value VL is similar to the case described above. It may be represented by a straight line L_max shown in FIG. Here, as the interruption of the current path in the negative electrode line NL, the system main relay SMR-G is turned off although the negative electrode line NL is disconnected or the system main relay SMR-G is driven on. It can be mentioned.

  As described above, when the current path in the positive electrode line PL and the negative electrode line NL is interrupted, the relationship between the current value IL and the voltage value VL becomes the same as when the failure of the current sensor 24 occurs. Therefore, it is necessary to distinguish between the interruption of the current path in the positive electrode line PL and the negative electrode line NL and the failure of the current sensor 24.

  This process will be described with reference to the flowchart shown in FIG. The process shown in FIG. 5 is executed by the controller 30. Further, the process shown in FIG. 5 is periodically repeated when the vehicle is running with the battery system in the activated state, similarly to the process shown in FIG.

  In FIG. 5, the processes of steps S301 to S304 are the same as the processes of steps S101 to S104 shown in FIG. In the process of step S304, as described in the first embodiment, instead of determining whether or not the condition of the above expression (1) is satisfied, the condition shown in the above expression (2) or the above expression (3) is satisfied. Whether or not it is satisfied can be determined. In step S304, when the condition shown in the above equation (1) is satisfied, the controller 30 detects the voltage value VL using the voltage sensor 23 in step S305.

  In step S306, the controller 30 determines whether or not the voltage value VL detected in the process of step S305 satisfies a condition represented by the following formula (4). Here, the process of step S305 can be omitted. In this case, in the process of step S301, it can be determined whether or not the voltage value VL detected last satisfies the condition shown in the following formula (4).

  In the determination by the above formula (4), it is determined whether or not the voltage value VL is higher than the lower limit value VL_min and lower than the upper limit value VL_max. In other words, in the determination by the following formula (4), it is determined whether or not the voltage value VL is within a predetermined voltage range defined by the lower limit value VL_min and the upper limit value VL_max.

  The lower limit value VL_min shown in the above equation (4) is a lower limit value that the voltage value VL can take. As described above, when the current path of the positive electrode line PL and the negative electrode line NL is interrupted and the capacitor C continues to be discharged, the voltage value VL becomes 0 [V]. For this reason, 0 [V] can be set as the lower limit VL_min. However, in consideration of the detection error of the voltage sensor 23, a voltage value VL larger than 0 [V] can also be set as the lower limit value VL_min.

  The upper limit value VL_max shown in the above equation (4) is an upper limit value that the voltage value VL can take. As described above, as the current path of the positive electrode line PL and the negative electrode line NL is interrupted, the voltage value VL continues to increase as the capacitor C continues to be charged. When the voltage value VL becomes equal to or higher than the predetermined value VL_th, the controller 30 prohibits the charging current from flowing through the capacitor C. Specifically, the controller 30 can stop the power generation by the motor generators MG1 and MG2 or leave the switching element 44 of the booster circuit 40 off.

  For this reason, the predetermined value VL_th can be set as the upper limit value VL_max. However, the voltage value VL considering the detection error of the voltage sensor 23 with respect to the predetermined value VL_th can be set as the upper limit value VL_max.

  On the other hand, the lower limit value VL_min and the upper limit value VL_max can be set in consideration of the voltage value VB of the assembled battery 10. When controlling charging / discharging of the battery pack 10, a lower limit value VB_min and an upper limit value VB_max are set for the voltage value VB. Here, discharging of the assembled battery 10 is controlled so that the voltage value VB does not become the lower limit value VB_min or less, and charging of the assembled battery 10 is controlled so that the voltage value VB does not become the upper limit value VB_max or more. The lower limit value VB_min is set to suppress overdischarge of the assembled battery 10, and the upper limit value VB_max is set to suppress overcharge of the assembled battery 10. The upper limit value VB_max is lower than the predetermined value VL_th described above.

  When the current paths in the positive electrode line PL and the negative electrode line NL are not interrupted, the voltage value VL is equal to the voltage value VB. In this case, voltage value VL changes between lower limit value VB_min and upper limit value VB_max. Therefore, the lower limit value VB_min can be set as the lower limit value VL_min, and the upper limit value VB_max can be set as the upper limit value VL_max.

  In step S306 shown in FIG. 5, when the voltage value VL does not satisfy the condition shown in the above equation (4), the controller 30 cuts off the current path in at least one of the positive line PL and the negative line NL in step S307. Is determined. At this time, the controller 30 can set a flag indicating interruption of the current path. When this flag is set, a warning can be given to the user or the like. As a warning means, a known method can be appropriately employed. For example, a warning can be given by display on a display or generation of sound.

  When the current path in at least one of the positive electrode line PL and the negative electrode line NL is interrupted and the capacitor C continues to be discharged, the voltage value VL becomes 0 [V] as described above. During the process of step S301, the voltage value VL may drop to 0 [V]. In this case, the voltage value VL is equal to or lower than the lower limit value VL_min, and the condition shown in the above formula (4) is not satisfied. Thereby, based on the process of step S306, S307, it can discriminate | determine that the electric current path is interrupted | blocked.

  When the current path in at least one of the positive line PL and the negative line NL is interrupted and the capacitor C continues to be charged, the voltage value VL rises to the predetermined value VL_th as described above. During the process of step S301, the voltage value VL may rise to the upper limit value VL_max. In this case, the voltage value VL becomes equal to or higher than the upper limit value VL_max, and the condition shown in the above equation (4) is not satisfied. Thereby, based on the process of step S306, S307, it can discriminate | determine that the electric current path is interrupted | blocked.

  In step S306, when the voltage value VL satisfies the condition shown in the above equation (4), the controller 30 determines in step S308 that a failure of the current sensor 24 has occurred. The process in step S308 is the same as the process in step S105 shown in FIG. When the current path in the positive electrode line PL and the negative electrode line NL is not interrupted, that is, when the assembled battery 10 and the capacitor C are connected, the voltage value VL is higher than the lower limit value VL_min and higher than the upper limit value VL_max. Lower. Thereby, when the condition shown in the above equation (1) is satisfied, it can be determined that a failure of the current sensor 24 has occurred.

  According to the present embodiment, it is possible to determine that the failure of the current sensor 24 has occurred based on the ratios k_last and k_now while distinguishing between the failure of the current sensor 24 and the interruption of the current path.

  The present embodiment can also be applied to the second embodiment. Specifically, steps S305 to S308 shown in FIG. 5 can be performed instead of the step S208 shown in FIG. That is, after determining that the count value c_kc is larger than the predetermined value c_th, it is possible to distinguish between failure of the current sensor 24 and interruption of the current path based on the voltage value VL.

  Embodiment 4 of the present invention will be described. In the present embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, differences from the first embodiment will be mainly described.

  In the present embodiment, as in the first embodiment, after comparing the ratios k_last and k_now, based on the change in the current value IL when the control for intentionally changing the current value IL is performed, It is determined whether or not a failure has occurred. In order to intentionally change the current value IL, in this embodiment, as shown in FIG. 6, the rotational speed (operating state of the load) of the motor / generator MG1 is changed. FIG. 6 is a collinear diagram (an example) showing the relationship between the rotational speed of the engine 54 and the rotational speeds of the motor generators MG1 and MG2.

  The dotted line shown in FIG. 6 shows the state before changing the rotational speed of the motor / generator MG1, and the solid line shown in FIG. 6 shows the state after changing the rotational speed of the motor / generator MG1. As shown in FIG. 6, the rotational speed of the engine 54 is changed in accordance with the change of the rotational speed of the motor / generator MG1. In FIG. 6, the rotational speed of the motor / generator MG <b> 1 is changed while keeping the traveling speed of the vehicle constant. If the rotational speed of the motor / generator MG1 is changed under the condition that the traveling speed of the vehicle is kept constant, the current value IL can be changed while maintaining the traveling performance of the vehicle. If the booster circuit 40 is a system connected to a load, the current value IL can be changed by changing the operating state of the load.

  Next, in the present embodiment, processing for determining a failure of the current sensor 24 will be described with reference to a flowchart shown in FIG. The process shown in FIG. 7 is executed by the controller 30. Further, the process shown in FIG. 7 is repeated at a predetermined cycle when the vehicle is running with the battery system in the activated state, similarly to the process shown in FIG.

  The processing from step S401 to S404 is the same as the processing from step S101 to S104 shown in FIG. In the process of step S404, as described in the first embodiment, instead of determining whether or not the condition of the expression (1) is satisfied, the condition shown in the expression (2) or the expression (3) is satisfied. Whether or not it is satisfied can be determined. In step S404, when the condition shown in the above equation (1) is satisfied, the controller 30 changes the rotational speed of the motor / generator MG1 in step S405 as described with reference to FIG. Then, the controller 30 detects the current value IL using the current sensor 24 in step S406.

  In step S407, the controller 30 determines whether or not the difference (absolute value) between the current value IL_last and the current value IL_now is equal to or smaller than a predetermined difference ΔIL_th. The predetermined difference ΔIL_th is a threshold value for determining whether or not the current value IL changes according to the change in the rotation speed of the motor / generator MG1. When a failure occurs in the current sensor 24, the current values IL_last and IL_now are equal to each other, and the difference between the current values IL_last and IL_now is zero. For this reason, the predetermined difference ΔIL_th can be set to zero. However, the predetermined difference ΔIL_th can be set to a value larger than 0 in consideration of the detection error of the current sensor 24 and the like. Information on the predetermined difference ΔIL_th can be stored in the memory 31.

  The current value IL_last is the current value IL before performing the process of step S405. This current value IL_last is detected in the process of step S401. The current value IL_now is the current value IL after the process of step S405 is performed. This current value IL_now is detected in the process of step S406.

  When the difference (absolute value) between the current values IL_last and IL_now is equal to or smaller than the predetermined difference ΔIL_th, the controller 30 determines in step S408 that a failure of the current sensor 24 has occurred. The process of step S408 is the same as the process of step S105 shown in FIG. On the other hand, when the difference (absolute value) between the current values IL_last and IL_now is larger than the predetermined difference ΔIL_th, the controller 30 ends the process shown in FIG.

  In the present embodiment, it is confirmed whether or not the current value IL changes under the condition that the current value IL changes when the condition expressed by the above formula (1) is satisfied. When the current value IL does not change, in other words, when the difference (absolute value) between the current values IL_last and IL_now is equal to or smaller than the predetermined difference ΔIL_th, it is determined that a failure of the current sensor 24 has occurred. In this way, not only the condition shown in the above formula (1) is satisfied, but also by confirming that the current value IL does not change under the condition that the current value IL changes, a failure of the current sensor 24 occurs. It becomes easier to confirm that.

  The present embodiment can also be applied to the second embodiment. That is, instead of the process of step S208 shown in FIG. 4, the processes of steps S405 to S408 shown in FIG. 7 can be performed. That is, in step S207 shown in FIG. 4, when the count value c_kc is larger than the predetermined value c_th, the rotational speed of the motor / generator MG1 is changed, and the difference (absolute value) between the current values IL_last and IL_now is equal to or smaller than the predetermined difference ΔIL_th. It can be determined that a failure of the current sensor 24 has occurred.

  The present embodiment can also be applied to the third embodiment. That is, instead of the process of step S308 shown in FIG. 5, the processes of steps S405 to S408 shown in FIG. 7 can be performed. That is, in step S306 shown in FIG. 5, when the voltage value VL satisfies the condition shown in the above equation (4), the rotational speed of the motor / generator MG1 is changed, and the difference (absolute value) between the current values IL_last and IL_now is determined. After confirming that the difference is equal to or less than the predetermined difference ΔIL_th, it can be determined that a failure of the current sensor 24 has occurred.

  Furthermore, this embodiment and Embodiments 2 and 3 can be combined. The process at this time is shown in FIG. In the flowchart shown in FIG. 8, the same reference numerals are used for the same processes as those described in FIGS. 4, 5, and 7.

  In step S207 shown in FIG. 4, when the count value c_kc is larger than the predetermined value c_th, the voltage value VL is detected as in the process of step S305 shown in FIG. Then, similarly to the process in step S306 shown in FIG. 5, it is determined whether or not the voltage value VL detected in the process in step S305 satisfies the condition shown in the above equation (4).

  When the voltage value VL does not satisfy the condition shown in the above equation (4), the process of step S307 shown in FIG. 5 is performed. On the other hand, when the voltage value VL satisfies the condition shown in the above equation (4), the processing after step S405 shown in FIG. 7 is performed.

10: assembled battery, 21, 23: voltage sensor, 22, 24: current sensor,
30: Controller, 40: Booster circuit, 51: Inverter, 52: Drive wheel,
53: Power split mechanism, 54: Engine, C: Capacitor, PL: Positive electrode line,
NL: Negative electrode line

Claims (5)

A power storage device for charging and discharging; and
A booster circuit connected to the power storage device via a positive electrode line and a negative electrode line, including a reactor, and boosting an output voltage of the power storage device;
A capacitor connected to the positive line and the negative line;
A current sensor for detecting a current value of the reactor;
A voltage sensor for detecting a voltage value of the power storage device or the capacitor;
A controller for discriminating a failure in which a current value detected by the current sensor is fixed,
The controller is
Calculating a ratio indicating a ratio of the voltage value change amount to the current value change amount;
A value obtained by comparing two ratios calculated at different timings is the ratio when the current value and the voltage value are changed, and the current value is not changed due to the voltage value changing. The occurrence of the failure is determined when a value compared with a predetermined ratio that defines the ratio at the time is within a possible predetermined range;
A power storage system characterized by that. A power storage device for charging and discharging; and
A booster circuit connected to the power storage device via a positive electrode line and a negative electrode line, including a reactor, and boosting an output voltage of the power storage device;
A capacitor connected to the positive line and the negative line;
A current sensor for detecting a current value of the reactor;
A voltage sensor for detecting a voltage value of the power storage device or the capacitor;
A controller for discriminating a failure in which a current value detected by the current sensor is fixed,
The controller is
Calculating a ratio indicating a ratio of the voltage value change amount to the current value change amount;
Each time the ratio is calculated, a value obtained by comparing the two ratios calculated at different timings, the ratio when the current value and the voltage value change, and the voltage value change. It is determined whether or not a value obtained by comparing a predetermined ratio that defines the ratio when the current value is not changed is within a predetermined range,
While the value obtained by comparing the two ratios calculated at different timings is within the predetermined range, the count value is incremented,
When the count value is greater than a predetermined value, the occurrence of the failure is determined.
A power storage system characterized by that. A power storage device for charging and discharging; and
A booster circuit connected to the power storage device via a positive electrode line and a negative electrode line, including a reactor, and boosting an output voltage of the power storage device;
A load connected to the booster circuit;
A capacitor connected to the positive line and the negative line;
A current sensor for detecting a current value of the reactor;
A voltage sensor for detecting a voltage value of the power storage device or the capacitor;
A controller for discriminating a failure in which a current value detected by the current sensor is fixed,
The controller is
Calculating a ratio indicating a ratio of the voltage value change amount to the current value change amount;
A value obtained by comparing two ratios calculated at different timings is the ratio when the current value and the voltage value are changed, and the current value is not changed due to the voltage value changing. When the value compared with the predetermined ratio defining the ratio at the time is within a predetermined range that can be taken, the operating state of the load is changed,
When the difference between the current values before and after changing the operating state of the load is a predetermined difference or less, the occurrence of the failure is determined.
A power storage system characterized by that. A power storage device for charging and discharging; and
A booster circuit connected to the power storage device via a positive electrode line and a negative electrode line, including a reactor, and boosting an output voltage of the power storage device;
A capacitor connected to the positive line and the negative line;
A current sensor for detecting a current value of the reactor;
A voltage sensor for detecting a voltage value of the capacitor;
A controller for discriminating a failure in which a current value detected by the current sensor is fixed,
The controller is
Calculating a ratio indicating a ratio of the voltage value change amount to the current value change amount;
A value obtained by comparing two ratios calculated at different timings is the ratio when the current value and the voltage value are changed, and the current value is not changed due to the voltage value changing. Determining whether the voltage value is within a predetermined voltage range when a value compared with a predetermined ratio that defines the ratio is within a possible predetermined range;
Determining the occurrence of the fault when the voltage value is within the predetermined voltage range;
A power storage system characterized by that. The controller determines that a current path for charging / discharging the power storage device is interrupted in a state where charging / discharging of the capacitor is permitted when the voltage value is outside the predetermined voltage range. The electrical storage system of Claim 4 characterized by the above-mentioned.