JP6632372B2 - State determination device and state determination method - Google Patents

Description

  The present invention relates to a state determination device and a state determination method.

  2. Description of the Related Art Conventionally, for example, a vehicle such as a hybrid vehicle or an electric vehicle includes a power supply that supplies power to a motor that is a power source. As a monitoring device that monitors the state of the power supply, a monitoring device using a DC voltage application method is known.

  Since the power supply is configured to be insulated from the vehicle body, the monitoring device has a function of monitoring the insulation state of the power supply, in other words, a function of detecting deterioration of the insulation resistance of the power supply. For example, the monitoring device connects a high-voltage battery mounted on a vehicle, a GND (ground) of a vehicle body, and a vehicle insulation resistor in series to supply a current to a flying capacitor that is insulated from the high-voltage battery, and a charged voltage of the flying capacitor. , The deterioration of the insulation resistance of the power supply is detected.

  Further, since the high-voltage battery is composed of a plurality of power supply stacks, the monitoring device also has a monitoring function of monitoring the power supply stack so that each power supply stack does not become overcharged, and further monitors the monitoring function. It also has the function of performing The monitoring device monitors the overcharge of each power supply stack based on the voltage of the flying capacitor connected in series to each power supply stack even in such double monitoring.

  In recent years, a monitoring device that realizes the plurality of monitoring functions with one circuit has been known (for example, see Patent Document 1). For example, the monitoring device measures the voltage by switching the capacitance of the flying capacitor, and compares the detected voltage states before and after the switching to detect a circuit failure.

JP 2004-245743 A

  However, the above technique cannot detect a failure of the switching element that switches the capacitance of the flying capacitor. For this reason, the monitoring process may be executed without noticing the failure of the switch element, and an erroneous determination may occur, and it is hard to say that the reliability is high.

  The disclosed technology has been made in view of the above, and has as its object to provide a state determination device and a state determination method that can detect a failure of a switch element that switches the capacitance of a flying capacitor.

  In one aspect, a state determination device disclosed in the present application includes a first capacitor connected to an insulated power supply, and a second capacitor connected to the power supply and connected to the first capacitor via a changeover switch. Controlling the changeover switch to obtain a first voltage value of the power storage unit that is charged using the first charging path including the first capacitor without including the second capacitor. A first obtaining unit, and a second obtaining unit that controls the changeover switch to obtain a second voltage value of the power storage unit charged using a second charging path including the second capacitor and the first capacitor. A determination unit that determines a state of the changeover switch based on the first voltage value and the second voltage value.

  ADVANTAGE OF THE INVENTION According to this invention, the failure of the switch element which switches the capacitance of a flying capacitor can be detected.

FIG. 1 is a block diagram illustrating a configuration example of a charge / discharge system including a power supply monitoring device according to an embodiment. FIG. 2 is a block diagram illustrating a configuration example of the power supply monitoring device. FIG. 3 is a diagram illustrating a configuration example of the voltage detection circuit unit. FIG. 4 is a diagram illustrating a charging path for charging the first capacitor with the voltage of the first stack. FIG. 5 is a diagram showing a discharge path for discharging the charged first capacitor. FIG. 6 is a diagram illustrating a charging path for charging the first capacitor with the voltage of the second stack. FIG. 7 is a diagram illustrating a charging path when detecting deterioration of the insulation resistance on the positive electrode side of the battery pack. FIG. 8 is a diagram showing a discharge path for discharging a charged capacitor. FIG. 9 is a diagram showing a charging path when detecting deterioration of the insulation resistance on the negative electrode side of the battery pack. FIG. 10 is a diagram illustrating a charging path for charging both the first capacitor and the second capacitor with the voltage of the first stack. FIG. 11 is a diagram illustrating a discharge path for discharging the charged first and second capacitors. FIG. 12 is a flowchart illustrating a part of the processing procedure of the processing executed by the power supply monitoring system. FIG. 13 is a flowchart illustrating a part of a processing procedure of a changeover switch monitoring process performed by the power supply monitoring system. FIG. 14 is a diagram showing a time chart of the monitoring process of the changeover switch. FIG. 15 is a diagram illustrating a threshold value for failure determination.

  Hereinafter, embodiments of a state determination device and a state determination method disclosed in the present application will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

<1. Configuration of charge / discharge system>
FIG. 1 is a block diagram illustrating a configuration example of a charge / discharge system including a power supply monitoring device according to an embodiment. The charge / discharge system 1 is mounted on a vehicle such as a hybrid electric vehicle (HEV), an electric vehicle (EV), and a fuel cell vehicle (FCV) (not shown). The charging / discharging system 1 is a system that performs charging / discharging of a power supply that supplies electric power to a motor as a power source of a vehicle.

  Specifically, the charging / discharging system 1 includes the battery pack 10, the power supply monitoring system 20, the vehicle control device 30, the motor 40, the voltage converter 50, and the fail-safe relay 60. Further, the power supply monitoring system 20 includes a plurality of satellite boards 22 having a monitor IC (Integrated Circuit) 21 and the like, and a power supply monitoring device 23.

  The battery pack 10 is a power supply (battery) insulated from a vehicle body (not shown) and includes a plurality of blocks 11. One block 11 includes a plurality of, for example, two battery stacks 12 connected in series. Further, one battery stack 12 includes, for example, a plurality of battery cells 13 connected in series.

  The numbers of the blocks 11, the battery stacks 12, and the battery cells 13 are not limited to those described above or illustrated. Further, as the above-described battery pack 10, for example, a lithium ion secondary battery or a nickel hydride secondary battery can be used, but the present invention is not limited to this.

  Each of the plurality of battery cells 13 is electrically connected to a monitor IC 21 provided on a satellite substrate 22. The voltage of each battery cell 13 is detected by the monitor IC 21. The monitor IC 21 includes a plurality of first monitor ICs 21a and a plurality of second monitor ICs 21b, and the first and second monitor ICs 21a and 21b each detect the voltage of the battery cell 13 of one battery stack 12.

  The power supply monitoring device 23 has a function of monitoring each individual voltage of the plurality of battery cells 13 and a function of monitoring the voltage of each battery stack 12. That is, the power supply monitoring device 23 monitors the state of charge of the battery pack 10. Further, the power supply monitoring device 23 monitors the state of the changeover switch that switches the capacitor.

  Specifically, the power supply monitoring device 23 transmits a voltage detection request to the monitor IC 21 to detect the individual voltages of the plurality of battery cells 13 and receives the detection result via the communication line L1. , The voltage of the battery cell 13 is monitored. In addition, the power supply monitoring device 23 directly measures the stack voltage by charging a capacitor (to be described later) (hereinafter, sometimes referred to as a “stack voltage”) to a capacitor described later via the conductor L2, and The state of charge of the battery 10 is monitored.

  It is preferable that the power supply monitoring device 23 also has a function of determining whether the monitor IC 21 is operating normally. Specifically, for example, the power supply monitoring device 23 compares the stack voltage obtained by adding the individual voltages of the respective battery cells 13 received from the monitor IC 21 with the directly detected stack voltage, and if the difference between the two is allowable, When the value is larger than the value, it is determined that the monitor IC 21 is abnormal. Then, when it is determined that the monitor IC 21 is abnormal, the power supply monitoring device 23 may disconnect the fail-safe relay 60, for example, so that the battery cell 13 is not charged or discharged.

  The power supply monitoring device 23 detects the deterioration of the insulation resistance (described later) of the power supply monitoring system 20, which will be described later. Here, the deterioration of the insulation resistance means that, for example, the resistance value of the insulation resistance has decreased and the leakage of the battery pack 10 has occurred.

  The vehicle control device 30 controls the vehicle by charging and discharging the assembled battery 10 according to the state of charge of the assembled battery 10. Specifically, the vehicle control device 30 uses the voltage converter 50 to convert the voltage charged in the battery pack 10 from DC to AC, and supplies the converted voltage to the motor 40 to drive the motor 40. Let it. Thereby, the battery pack 10 is discharged.

  Further, the vehicle control device 30 converts the voltage generated by the regenerative braking of the motor 40 from an AC voltage to a DC voltage by the voltage converter 50 and supplies the voltage to the battery pack 10. Thereby, the battery pack 10 is charged. As described above, the vehicle control device 30 monitors the voltage of the battery pack 10 based on the state of charge of the battery pack 10 acquired from the power supply monitoring device 23, and performs control according to the monitoring result.

<2. Configuration of power supply monitoring device>
Next, the configuration of the power supply monitoring device 23 will be described. FIG. 2 is a block diagram illustrating a configuration example of the power supply monitoring device 23. 2, the satellite board 22, the communication line L1, and the like are omitted. In addition, FIG. 2 shows one of the plurality of blocks 11 for convenience of understanding, and hereinafter, one of the two battery stacks 12 in the block 11 is referred to as a “first stack 12a” and the other May be described as “second stack 12b”.

  The power supply monitoring device 23 is, for example, an electronic control unit (ECU), and includes a voltage detection circuit unit 24, an A / D conversion unit 25, and a control unit 26, as shown in FIG. The voltage detection circuit unit 24 includes a circuit for performing detection of each stack voltage, deterioration detection of insulation resistance, failure detection of a switch for switching a capacitor, and the like.

  Here, for example, if the voltage detection circuit unit 24 has a configuration in which a circuit for detecting each stack voltage and a circuit for detecting insulation resistance deterioration are separately provided, the configuration of the power supply monitoring device 23 is complicated. And the cost may be increased.

  Therefore, in the power supply monitoring device 23 according to the present embodiment, detection of each stack voltage and deterioration detection of the insulation resistance can be performed while simplifying the configuration of the device and suppressing an increase in cost. Hereinafter, the configuration of the power supply monitoring device 23 will be described in more detail.

  FIG. 3 is a diagram illustrating a configuration example of the voltage detection circuit unit 24 of the power supply monitoring device 23. As shown in FIG. 3, the voltage detection circuit unit 24 includes first and second capacitors C1 and C2, first switch S1 to sixth switch S6, changeover switch S7, first resistor R1 to seventh resistor R7, Is provided. Further, the battery pack 10 has an insulation resistance Rp on the positive electrode side and an insulation resistance Rn on the negative electrode side. In the embodiment, the insulation resistances Rp and Rn indicate a combined resistance value of the mounted resistance and a resistance virtually representing the insulation with respect to the vehicle body GND, but may be any of the mounted resistance and the virtual resistance. It does not matter.

  In the voltage detection circuit section 24, a flying capacitor method is applied, and as described later, the first capacitor C1 is charged with the voltage of each of the stacks 12a and 12b, and then the voltage of the first capacitor C1 is charged to each of the stacks 12a and 12b. Detected as voltage.

  Specifically, the voltage detection circuit section 24 is divided into a charging side circuit and a discharging side circuit via the first and second capacitors C1 and C2. Hereinafter, the first and second capacitors C1 and C2 may be collectively referred to as “capacitor C”.

  The charging-side circuit is a portion that includes a path in which each of the stacks 12a and 12b of the battery pack 10 is connected to the capacitor C and charges the capacitor C with the voltage of each of the stacks 12a and 12b. The discharging side circuit is a part including a path for discharging the voltage charged in the capacitor C.

  By controlling the ON / OFF of each of the switches S1 to S7, the charging and discharging of the capacitor C is controlled. The switches S1 to S7 may be, for example, solid state relays (SSRs), but are not limited thereto. The first to seventh resistors R1 to R7 are voltage detection resistors for detecting the voltage of the capacitor C.

  In the charging-side circuit of the voltage detection circuit unit 24, each of the first stack 12a and the second stack 12b is connected in parallel to the capacitor C. That is, both ends of the capacitor C are connected to the positive electrode and the negative electrode of the first stack 12a, and are also connected to the positive electrode and the negative electrode of the second stack 12b.

  A first resistor R1, a first switch S1, and a fifth resistor R5 are provided in series between the positive electrode side of the first stack 12a and the capacitor C. A second resistor R2 and a second switch S2 are provided in series between them.

  Further, a third resistor R3, a third switch S3, and a fifth resistor R5 are provided in series between the positive electrode side of the second stack 12b and the capacitor C. A fourth resistor R4 and a fourth switch S4 are provided in series between them.

  In the discharge side circuit of the voltage detection circuit unit 24, a fifth switch S5 is provided on a path on the positive side of the first stack 12a and the second stack 12b, and a fifth switch S5 is provided between one end of the fifth switch S5 and the capacitor C. A resistor R5 is provided. In addition, a sixth switch S6 is provided in a path on the negative electrode side of the first and second stacks 12a and 12b, and one end of the sixth switch S6 is connected to the capacitor C.

  The other end of the fifth switch S5 is connected to the A / D converter 25, branches off in the middle, and is connected to the vehicle body GND via the sixth resistor R6. The other end of the sixth switch S6 is connected to the vehicle body GND via a seventh resistor R7. Note that the vehicle body GND is an example of a ground point.

  The A / D conversion unit 25 converts an analog value indicating a voltage at the connection point A of the voltage detection circuit unit 24 into a digital value, and outputs the converted digital value to the control unit 26.

  Next, the first and second capacitors C1 and C2 will be described in detail. Since it is desirable that the process of detecting the voltage of each of the stacks 12a and 12b be completed in a relatively short time, the capacitance used in the capacitor used for voltage detection is compared so that the capacitor can be charged in a short time. The smaller is preferable.

  On the other hand, a capacitor used for detecting deterioration of the insulation resistances Rp and Rn preferably has a relatively large capacitance. That is, the vehicle has a stray capacitance that is not intended at the time of design. When detecting the deterioration of the insulation resistances Rp and Rn, the influence of the stray capacitance may make it impossible to accurately detect the voltage of the capacitor, and the accuracy of the deterioration detection may decrease. Therefore, it is preferable to make the capacitance of the capacitor used for detecting the deterioration of the insulation resistances Rp and Rn relatively large to reduce the influence of the stray capacitance on the entire capacitance.

  Therefore, in the present embodiment, the first and second capacitors C1 and C2 are configured as follows. Specifically, the first capacitor C1 is connected in series to the fifth resistor R5. The second capacitor C2 is connected in series to the changeover switch S7.

  Further, the second capacitor C2 and the changeover switch S7 are connected in parallel to the first capacitor C1. Therefore, by controlling the on / off of the changeover switch S7, the capacitors connected in the charging-side circuit and the discharging-side circuit can be easily switched, so that the overall capacitance of each circuit can be made variable. it can.

  Specifically, for example, when the changeover switch S7 is turned off during the process of detecting the voltage of each of the stacks 12a and 12b, only the first capacitor C1 is connected in the charging-side circuit and the discharging-side circuit. The processing is performed with a small capacitance.

  On the other hand, when the changeover switch S7 is turned on during the process of detecting the deterioration of the insulation resistances Rp and Rn, the first and second capacitors C1 and C2 are connected in the charge-side circuit and the discharge-side circuit. Processing will be performed with a large capacitance.

  Here, the capacitance of the second capacitor C2 is set to a value larger than the stray capacitance. Specifically, when the stray capacitance of the vehicle is about 0.1 μF, the capacitance of the second capacitor C2 is set to about 20 times, that is, 2.2 μF. In such a case, the capacitance of the first capacitor C1 is, for example, 0.165 μF. As described above, the capacitance of the second capacitor C2 becomes larger than the capacitance of the first capacitor.

  This makes it possible to further increase the capacitance of the capacitor used for detecting the deterioration of the insulation resistances Rp and Rn, that is, the combined capacitance of the first and second capacitors C1 and C2, and thus the floating of the entire capacitance. The effect of the capacity can be further reduced.

  Thus, the first capacitor C1 is used for both detecting the voltage of each of the stacks 12a and 12b and detecting the deterioration of the insulation resistances Rp and Rn. The second capacitor C2 is used for detecting deterioration of the insulation resistances Rp and Rn.

  Next, charging and discharging of the voltage detection circuit unit 24 configured as described above will be described. First, charging and discharging of the first capacitor C1 performed to detect the voltages of the first and second stacks 12a and 12b will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating a charging path for charging the first capacitor C1 with the voltage of the first stack 12a. FIG. 5 is a diagram illustrating a discharging path for discharging the charged first capacitor C1, and FIG. 6 is a diagram illustrating a charging path for charging the first capacitor C1 with the voltage of the second stack 12b. is there.

  In the power supply monitoring device 23, the first capacitor C1 is charged for each of the first and second stacks 12a and 12b. First, an example in which the first capacitor C1 is charged with the voltage of the first stack 12a (hereinafter, sometimes referred to as "first stack voltage") will be described. As shown in FIG. The switch S2 is turned on, and the other switches S3 to S7 are turned off.

  Accordingly, the positive electrode side of the first stack 12a is connected to the negative electrode of the first stack 12a via the first resistor R1, the first switch S1, the fifth resistor R5, the first capacitor C1, the second switch S2, and the second resistor R2. Connected to the side. That is, a first path P1 connecting the first stack 12a and the first capacitor C1 is formed, and the first capacitor C1 is charged with the first stack voltage.

  Then, after a predetermined time has elapsed since the first path P1 was formed, the voltage of the first capacitor C1 is discharged. Specifically, as shown in FIG. 5, the first switch S1 and the second switch S2 are turned off, and the fifth switch S5 and the sixth switch S6 are turned on.

  As a result, a second path P2 serving as a discharge path is formed in the voltage detection circuit section 24. Since the A / D converter 25 is connected to the other end of the fifth switch S5, when the second path P2 is formed, the voltage of the first capacitor C1 (that is, the first stack voltage) is A / D converted. Input to the unit 25. The A / D converter 25 converts the analog value input at the moment when the fifth and sixth switches S5 and S6 are turned on to a digital value and outputs the digital value to the controller 26. As a result, the first stack voltage is detected. The first stack voltage detected at this time, that is, the voltage of the capacitor C is “VC1”.

  Next, an example in which the first capacitor C1 is charged with the voltage of the second stack 12b (hereinafter, sometimes referred to as “second stack voltage”) will be described. As shown in FIG. 6, the third switch S3 and the fourth switch S4 are turned on, and the other switches S1, S2, S5 to S7 are turned off.

  Thereby, the positive electrode side of the second stack 12b is connected to the negative electrode of the second stack 12b via the third resistor R3, the third switch S3, the fifth resistor R5, the first capacitor C1, the fourth switch S4, and the fourth resistor R4. Connected to the side. That is, the third path P3 connecting the second stack 12b and the first capacitor C1 is formed, and the first capacitor C1 is charged with the second stack voltage. Note that the above-described first and third paths P1 and P3 are examples of a first charging path.

  After a lapse of a predetermined time from the formation of the third path P3, the third and fourth switches S3 and S4 are turned off, and the fifth and sixth switches S5 and S6 are turned on. The voltage of C1 is discharged (see FIG. 5).

  As a result, the second path P2 is formed in the voltage detection circuit section 24, and the voltage of the first capacitor C1 (that is, the second stack voltage) is input to the A / D conversion section 25. Then, the A / D converter 25 converts the analog value of the input voltage into a digital value and outputs the digital value to the control unit 26 in the same manner as described above. As a result, the second stack voltage is detected.

  In this manner, the first stack voltage and the second stack voltage can be detected by switching the path on the discharging side and the path on the charging side to charge and discharge the first capacitor C1.

  In the detection processing of the first and second stack voltages, the first capacitor C1 does not need to be fully charged. That is, for example, in the detection processing of the first and second stack voltages, charging is performed for a predetermined time shorter than the time required for full charge, and the first and second stack voltages are estimated based on the charged voltages. You may. As a result, the processing time for detecting the first and second stack voltages can be reduced.

  Further, as shown in FIG. 3, the circuit of the voltage detection circuit unit 24 is provided with the positive-side insulation resistance Rp and the negative-side insulation resistance Rn of the battery pack 10 described above. Each of the insulation resistances Rp and Rn is a combined resistance of the mounted resistance and a resistance virtually representing insulation with respect to the vehicle body GND. Here, the mounted resistance and the virtual resistance It does not matter which one it is.

  The resistance value of each of the insulation resistances Rp and Rn is set to a value which is sufficiently large that current is hardly supplied in a normal state, for example, several MΩ. However, when the insulation resistances Rp and Rn are abnormal, the resistance value is reduced to such a level that, for example, the battery pack 10 is short-circuited to the vehicle body GND or the like, or close to a short-circuit and is energized.

  Here, the charging and discharging of the capacitor C (that is, the first and second capacitors C1 and C2) performed to detect the deterioration of the insulation resistances Rp and Rn of the battery pack 10 will be described with reference to FIGS. explain.

  FIG. 7 is a diagram showing a charging path when detecting the deterioration of the insulation resistance Rp on the positive electrode side of the battery pack 10. FIG. 8 is a diagram illustrating a discharge path for discharging the charged capacitor C, and FIG. 9 is a diagram illustrating a charge path when detecting deterioration of the insulation resistance Rn on the negative electrode side of the battery pack 10. is there.

  First, when detecting the deterioration of the insulation resistance Rp on the positive electrode side, as shown in FIG. 7, the fourth switch S4, the fifth switch S5, and the changeover switch S7 are turned on, and the other switches S1 to S3, S6 are turned off. Is done. Thereby, the positive electrode side of the first stack 12a is connected via the insulation resistance Rp, the sixth resistance R6, the fifth switch S5, the fifth resistance R5, the capacitor C, the fourth switch S4, the fourth resistance R4, and the second stack 12b. To the negative side of the first stack 12a.

  That is, the fourth path P4 connecting the first and second stacks 12a and 12b and the capacitor C via the positive-side insulation resistance Rp is formed. At this time, when the resistance value of the insulation resistance Rp is normal, the fourth path P4 is hardly conductive, and when the insulation resistance Rp is deteriorated and the resistance value is reduced, the fourth path P4 is It becomes conductive.

  Then, after a predetermined time has elapsed since the fourth path P4 was formed, the voltage of the capacitor C is discharged. Specifically, as shown in FIG. 8, the fourth switch S4 is turned off and the sixth switch S6 is turned on. Thus, a fifth path P5 serving as a discharge path is formed in the voltage detection circuit unit 24. The voltage of the capacitor C detected at this time is referred to as “voltage VRp”, and the deterioration of the insulation resistance Rp is detected based on the voltage VRp, which will be described later.

  When detecting the deterioration of the insulation resistance Rn on the negative electrode side, as shown in FIG. 9, the first switch S1, the sixth switch S6, and the changeover switch S7 are turned on, and the other switches S2 to S5 are turned off. Thus, the positive electrode side of the first stack 12a is connected via the first resistor R1, the first switch S1, the fifth resistor R5, the capacitor C, the sixth switch S6, the seventh resistor R7, the insulation resistor Rn, and the second stack 12b. To the negative side of the first stack 12a.

  That is, a sixth path P6 connecting the first and second stacks 12a and 12b and the capacitor C via the negative-side insulation resistance Rn is formed. At this time, when the resistance value of the insulation resistance Rn is normal, the sixth path P6 is hardly conductive, and when the insulation resistance Rn is deteriorated and the resistance value is reduced, the sixth path P6 is It becomes conductive.

  Then, after a predetermined time has elapsed since the sixth path P6 was formed, the voltage of the capacitor C is discharged as shown in FIG. The voltage of the capacitor C detected at this time is referred to as “voltage VRn”, and the deterioration of the insulation resistance Rn is detected based on the voltage VRn, which will be described later. The above-described fourth and sixth paths P4 and P6 are examples of a second charging path.

  In the process of detecting deterioration of the insulation resistances Rp and Rn, charging is performed for a predetermined time shorter than the time required for full charge, and the charge voltage is used as the voltages VRp and VRn to detect deterioration of the insulation resistances Rp and Rn. I do.

  Next, a case where both the first capacitor C1 and the second capacitor C2 are charged and a case where they are discharged will be described. FIG. 10 is a diagram illustrating a charging path for charging both the first capacitor C1 and the second capacitor C2 with the voltage of the first stack 12a. FIG. 11 is a diagram showing a discharge path for discharging the charged first capacitor C1 and second capacitor C2.

  As shown in FIG. 10, the first switch S1, the second switch S2, and the changeover switch S7 are turned on, and the other switches S3 to S6 are turned off. Thus, the positive electrode side of the first stack 12a is connected to the first resistor R1, the first switch S1, the fifth resistor R5, the first capacitor C1, the changeover switch S7, the second capacitor C2, the second switch S2, and the second resistor R2. Is connected to the negative electrode side of the first stack 12a. That is, a seventh path P7 connecting the first stack 12a to the first capacitor C1 and the second capacitor C2 is formed, and the first capacitor C1 and the second capacitor C2 are charged with the first stack voltage.

  Then, after a predetermined time has elapsed since the seventh path P7 was formed, the voltages of the first capacitor C1 and the second capacitor C2 are discharged. Specifically, as shown in FIG. 11, after a predetermined time has elapsed since the seventh path P7 was formed, the first and second switches S1 and S2 are turned off, and the fifth and sixth switches S5 are turned off. , S6 are turned on to discharge the voltage of the first capacitor C1 and the voltage of the second capacitor C2.

  Thus, an eighth path P8 as a discharge path is formed in the voltage detection circuit section 24. Since the A / D converter 25 is connected to the other end of the fifth switch S5, when the eighth path P8 is formed, the voltage of the first capacitor C1 and the voltage of the second capacitor C2 (the voltage of the capacitor C) is increased. The signal is input to the A / D converter 25. The A / D converter 25 converts the analog value input at the moment when the fifth and sixth switches S5 and S6 are turned on to a digital value and outputs the digital value to the controller 26. Thereby, the voltage of the capacitor C is detected. The voltage of the capacitor C detected at this time, that is, the voltage of the first capacitor C1 and the voltage of the second capacitor C2 is referred to as “VC2”.

  Returning to the description of FIG. 2, the control unit 26 of the power supply monitoring device 23 is a microcomputer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The entire power supply monitoring device 23 including the unit 24 and the A / D conversion unit 25 is controlled.

  Specifically, the control unit 26 includes a charge / discharge path forming unit 26a, a voltage detecting unit 26b, a power monitoring unit 26c, and a switch monitoring unit 26d. The charging / discharging path forming unit 26a may be a first, third, fourth, sixth, and seventh paths P1, P3, P4, P6, and P7 that are charging paths, or second, fifth, and fifth paths that are discharging paths. Eight routes P2, P5, and P8 are formed.

  Specifically, the charge / discharge path forming unit 26a includes first to sixth switch control units 26a1 and a capacitor switching unit 26a2. The first to sixth switch control units 26a1 control the first to sixth switches S1 to S6 and the changeover switch S7 to form a charging path or a discharging path.

  Then, the capacitor switching unit 26a2 controls the switch S7 to switch the capacitor connected in the charging path or the discharging path. Specifically, the capacitor switching unit 26a2 controls the changeover switch S7 to control the charging path (first and third paths P1 and P3) including the first capacitor C1 without including the second capacitor C2, and the first and third paths. Switching is performed between the charging paths (the fourth and sixth paths P4 and P6) including the second capacitors C1 and C2. The capacitor switching unit 26a2 controls the first to sixth switches S1 to S6 and the switch S7 to form a charging path P7 including the first capacitor C1 and the second capacitor C2.

  Similarly, at the time of discharging, the capacitor switching unit 26a2 controls the changeover switch S7 so that the discharging path (the second path P2) that does not include the second capacitor C2 but includes the first capacitor C1, and the first and second paths. Switching is performed between the discharge path (the fifth path P5) including the capacitors C1 and C2. Further, the capacitor switching unit 26a2 controls the first to sixth switches S1 to S6 and the switch S7 to form a discharge path P8 including the first capacitor C1 and the second capacitor C2.

  Note that the switching patterns of the first to sixth switches S1 to S6 and the changeover switch S7 are stored in a storage unit such as a RAM and a ROM in advance. Then, the charging / discharging path forming unit 26a forms a charging path or a discharging path by reading the switching pattern from the storage unit at an appropriate timing.

  The voltage detection unit 26b detects the charged voltage of the first capacitor C1 and the like via the A / D conversion unit 25 when the charge / discharge path formation unit 26a forms the discharge path. The voltage detector 26b detects the first and second stack voltages and the voltages VRp, VRn, VC1, and VC2.

  Then, the voltage detection unit 26b outputs signals indicating the detected first and second stack voltages to the power supply monitoring unit 26c. The voltage detector 26b outputs the detected voltages VC1 and VC2 to the switch monitor 26d.

  Specifically, when the insulation resistance Rp and the insulation resistance Rn are not deteriorated and the resistance value is not reduced, the capacitor C is hardly charged, or a sufficiently small voltage is charged even if charged. . Therefore, the power supply monitoring unit 26c compares the voltage VRp and the voltage VRn with the threshold Va set to a relatively low value.

  Then, when the voltage VRp of the capacitor C becomes equal to or higher than the threshold value Va, the power supply monitoring unit 26c detects the deterioration of the insulation resistance Rp, in other words, determines that the insulation resistance Rp is abnormal. On the other hand, when the voltage VRp is less than the threshold value Va, the power supply monitoring unit 26c determines that the insulation resistance Rp is not deteriorated, in other words, the insulation resistance Rp is normal.

  Similarly, the power supply monitoring unit 26c detects the deterioration of the insulation resistance Rn when the voltage VRn is equal to or higher than the threshold value Va, while there is no deterioration in the insulation resistance Rn when the voltage VRn is less than the threshold value Va. Is determined. In the above description, the values to be compared with the voltages VRn and VRp are set to the same threshold value Va. However, the present invention is not limited to this, and threshold values set to different values may be used.

  Then, the power supply monitoring unit 26c outputs information indicating the result of the deterioration state of the insulation resistances Rp and Rn to the vehicle control device 30 and the like. Then, the vehicle control device 30 performs a vehicle control according to the deterioration state, a notification operation to the user, and the like.

  As described above, the power supply monitoring unit 26c determines the stack voltage based on the voltage of the capacitors charged in the first and third paths P1 and P3 or the fourth and sixth paths P4 and P6 switched by the capacitor switching unit 26a2. Detection and detection of deterioration of the insulation resistances Rp and Rn are performed.

  Specifically, the power supply monitoring unit 26c detects the stack voltage at the time of the first and third paths P1 and P3, and detects the deterioration of the insulation resistances Rp and Rn at the time of the fourth and sixth paths P4 and P6. Monitor the status of the power supply.

  Accordingly, the power supply monitoring device 23 can switch to a charging path having a different overall capacitance with a simple configuration that only controls the changeover switch S7, and can detect the stack voltage and the deterioration of the insulation resistances Rp and Rn. Can be performed with high accuracy.

  Further, since the voltage detection circuit unit 24 of the power supply monitoring device 23 has a common circuit configuration other than the capacitor, it is possible to detect the stack voltage and detect the deterioration of the insulation resistances Rp and Rn with a simpler configuration. it can.

  Further, in the power supply monitoring device 23, the current is kept flowing at the time of detecting the stack voltage and detecting the deterioration of the insulation resistances Rp and Rn.

  The switch monitoring unit 26d monitors the state of the changeover switch S7 using the voltage VC1 and the voltage VC2. Specifically, the switch monitoring unit 26d uses the same voltage source to determine the voltage of the capacitor C when the switch S7 is off (VC1) and the voltage of the capacitor C when the switch S7 is on (VC2). Are compared, it is determined whether the changeover switch S7 is operating normally.

  Specifically, when the changeover switch S7 is off, the battery is almost fully charged, and thus a voltage equivalent to the voltage of the voltage source, that is, the voltage of the first stack 12a is obtained. On the other hand, when the changeover switch S7 is on, the charge of the capacitor C is larger than when it is off, so that little charge is charged.

  Therefore, when the difference voltage “ΔV” between the voltages VC1 and VC2 is larger than the first threshold, the switch monitoring unit 26d determines that the changeover switch S7 is operating normally. When the difference voltage “ΔV” is equal to or smaller than the first threshold, the switch monitoring unit 26d determines that the changeover switch S7 has failed.

  Furthermore, if the voltage VC1 or VC2 is equal to or less than the second threshold, the switch monitoring unit 26d determines that the state of the changeover switch S7 is an ON-fixed state (an ON-fixed state) in which the switch cannot be turned off. On the other hand, if the voltage VC1 or VC2 is larger than the second threshold, the switch monitoring unit 26d determines that the state of the changeover switch S7 is an off-fixed state (an off-fixed state) that cannot be turned on. The first threshold can be set arbitrarily, but is preferably a value close to 0, for example, + 5V or -5V. The second threshold value can also be set arbitrarily. For example, a voltage equivalent to the voltage of the first stack 12a can be set.

  Then, the switch monitoring unit 26d outputs information indicating the result of the state determination of the changeover switch S7 to a host ECU such as the vehicle control device 30 or the like. Then, the host ECU performs a vehicle control or a notification operation to the user according to the determination result.

  For example, in the case of ON sticking, the stack voltage is measured with a small-capacitance capacitor, and full charge cannot be performed in a short time. For this reason, the host ECU does not execute the full charge control, ends the charging in a shorter time, and switches to the control for estimating the stack voltage.

  For example, the upper ECU measures the relational expression (calculation formula) between the time and the charging voltage by measuring the time-series change of the charging voltage and how much time can be charged in normal time. calculate. Then, the host ECU estimates the stack voltage from the voltage value after elapse of t seconds from the start of charging, using a relational expression.

  In addition, in the case of off-fixation, the host ECU measures the stack voltage with a large-capacity capacitor, so that an error such as a physical value conversion occurs and determines that there is a possibility of a functional loss of insulation abnormality detection. . For this reason, the host ECU switches constants when performing physical value conversion in software. For example, the host ECU may switch the threshold value used at the time of insulation abnormality detection to a higher value.

  Further, the host ECU compares the voltage value of the capacitor C with the reference value, and when it is determined that a leakage has occurred, the resistance value can be calculated backward from the charging voltage for a predetermined time.

  For example, the host ECU can estimate the stack voltage by equation (1). Here, VB is the stack voltage, Vc is the charge voltage of the flying capacitor, t is the charge time, and C is the capacitance of the flying capacitor. Rc is a circuit resistance, for example, a total resistance of R1, R5, and R2, or a total resistance of R3, R5, and R4.

  Further, the host ECU can also calculate the value of the insulation resistance using equation (2). Here, Ro is the insulation resistance, VB is the total battery voltage (the voltage of the stack 12a + the voltage of the stack 12b), Vc is the charge voltage of the flying capacitor, t is the charge time, C is the capacity of the flying capacitor. Rc is a circuit resistance, for example, a total resistance of R1, R5, and R7, or a total resistance of R6, R5, and R4.

  Note that, in equation (2), by using an equation in which VB is replaced with Vg, only the insulation resistance Rp can be calculated. At this time, Vg is the GND potential of the body, and Rc is the total resistance of R6, R5, and R4. Also, by using the equation in which VB is replaced by (Vb−Vg) in equation (2), only the insulation resistance Rn can be calculated. At this time, VB is the total battery voltage (the voltage of the stack 12a + the voltage of the stack 12b), Vg is the GND potential of the body, and Rc is the total resistance of R1, R5, and R7.

  In the above example, the processing executed by the host ECU when the failure of the changeover switch S7 occurs is exemplified. However, these processings can also be executed by the power supply monitoring device 23.

<3. Specific operation of charge state monitoring processing and deterioration detection processing>
Next, specific operations of the charge state monitoring process and the deterioration detection process performed by the power supply monitoring system 20 configured as described above will be described with reference to FIG. FIG. 12 is a flowchart illustrating a part of the processing procedure of the processing executed by the power supply monitoring system 20. Note that the various processes illustrated in FIG. 12 are executed based on control by the control unit 26 of the power supply monitoring device 23.

  As shown in FIG. 12, first, the control unit 26 controls the changeover switch S7 and the like to form the first path P1 (step S1). Next, after a predetermined time has elapsed, the controller 26 forms the second path P2 and detects the first stack voltage (Step S2).

  Subsequently, the control unit 26 controls the changeover switch S7 and the like to form the fourth path P4 (step S3), and after a lapse of a predetermined time, forms the fifth path P5 to detect the voltage VRp of the capacitor C (step S3). S4).

  Next, the control unit 26 controls the changeover switch S7 and the like to form the third path P3 (Step S5). Then, after a predetermined time has elapsed, the control unit 26 forms the second path P2 and detects the second stack voltage (Step S6).

  Subsequently, the control unit 26 controls the changeover switch S7 and the like to form the sixth path P6 (step S7), and after a lapse of a predetermined time, forms the fifth path P5 to detect the voltage VRn of the capacitor C (step S7). S8).

  Then, the control unit 26 detects the deterioration of the insulation resistances Rp and Rn based on the voltages VRp and VRn of the capacitor C detected in steps S4 and S8 (step S9). Next, the control unit 26 transmits the information indicating the deterioration state of the insulation resistances Rp and Rn as the deterioration detection result and the information indicating the first and second stack voltages as the monitoring result of the charging state of the battery pack 10 to the vehicle control device 30. (Step S10).

  In the above description, the detection is performed in the order of the first stack voltage, the voltage VRp, the second stack voltage, and the voltage VRn. However, this is merely an example, and the detection is not limited. can do.

<4. Specific operation of changeover switch monitoring processing>
Next, a specific operation of the changeover switch monitoring process performed by the power supply monitoring system 20 configured as described above will be described with reference to FIG. FIG. 13 is a flowchart illustrating a part of the processing procedure of the changeover switch monitoring processing executed by the power supply monitoring system 20. The various processes shown in FIG. 13 are executed based on control by the control unit 26 of the power supply monitoring device 23. The determination of the state of the changeover switch may be performed every time after the charge state monitoring processing or the deterioration detection processing, or may be performed once every several times.

  As illustrated in FIG. 13, when the voltage of the capacitor C is not 0 (Step S101: No), the control unit 26 performs the discharging process (Step S102), and then executes Step S103 and the subsequent steps. Note that the threshold value “0” shown here is an example, and does not limit the numerical value, but can have a certain width. Here, an example in which the discharging process is performed before the following process is performed will be described. However, the present invention is not limited to this, and the discharging process may be omitted.

  On the other hand, when the voltage of the capacitor C is 0 (Step S101: Yes) or when Step S102 is executed, the control unit 26 turns off the switch S7 (Step S103).

  Subsequently, the control unit 26 turns on the switch S1 and the switch S2 (step S104), waits for t seconds, and charges the capacitor C (step S105). Thereafter, the control unit 26 turns off the switches S1 and S2 (Step S106), turns on the switches S5 and S6 (Step S107), and acquires the voltage value (VC1) of the capacitor C (Step S108). . Thereafter, the control unit 26 turns off the switch S5 and the switch S6 (step S109), and executes a discharging process (step S110).

  Then, the control unit 26 turns on the changeover switch S7 (step S111), turns on the switches S1 and S2 (step S112), and waits for t seconds to charge the capacitor C (step S113). The charging time can be arbitrarily changed.

  Thereafter, the control unit 26 turns off the switches S1 and S2 (step S114), turns on the switches S5 and S6 (step S115), and acquires the voltage value (VC2) of the capacitor C (step S116). ), The switches S5 and S6 are turned off (step S117), and the discharging process is executed (step S118).

  In parallel with the discharge processing and the like, the control unit 26 calculates VC1−VC2 = ΔV (step S119), and when ΔV is equal to or smaller than the first threshold (step S120: Yes) and V1 (or V2) is equal to or smaller than the second threshold. If there is (Step S121: Yes), the ON fixation of the changeover switch S7 is detected (Step S122).

  On the other hand, when ΔV is equal to or smaller than the first threshold (Step S120: Yes) and V1 (or V2) is larger than the second threshold (Step S121: No), the control unit 26 detects that the changeover switch S7 is stuck off (Step S121). Step S123). When ΔV is larger than the first threshold (Step S120: No), the control unit 26 determines that there is no abnormality.

  Next, a time chart of the above processing will be described with reference to FIG. FIG. 14 is a diagram showing a time chart of the monitoring process of the changeover switch.

  As shown in FIG. 14, when the switches S1 and S2 are turned on and the changeover switch S7 is turned off, charging of the capacitor C is started. Then, at the timing when the switches S1 and S2 are turned off and the switches S5 and S6 are turned on and the discharge is started, the voltage (VC1) of the capacitor C is measured.

  Thereafter, the switches S1 and S2 are turned on, and the charging of the capacitor C is started when the changeover switch S7 is turned on. Then, at the timing when the switches S1 and S2 are turned off and the switches S5 and S6 are turned on and the discharge is started, the voltage (VC2) of the capacitor C is measured.

  As described above, the control unit 26 controls the off and on of the changeover switch S7 to execute charging of the capacitor C having a different capacity, and measures the voltage.

  Next, the threshold value used for the failure determination of the changeover switch S7 will be described with reference to FIG. FIG. 15 is a diagram illustrating a threshold value for failure determination. As shown in FIG. 15, the first threshold value is for determining the difference between VC1 and VC2, and varies depending on how much error is allowed, but is preferably close to zero. Further, the second threshold can be set from the relationship between the charging time and the charging voltage. As a result, when VC1 or VC2 is smaller than the second threshold value by a predetermined value or more, the changeover switch S7 may be stuck on, and it can be determined that there is a possibility of leakage. If VC1 or VC2 is larger than the second threshold by a predetermined value or more, it can be determined that the changeover switch S7 may be stuck off.

<5. Effects and Modifications>
As described above, the power supply monitoring device 23 according to the embodiment includes the first and second capacitors C1 and C2, the capacitor switching unit 26a2, and the power supply monitoring unit 26c. The first capacitor C1 is used for detecting a voltage of a power supply. The second capacitor C2 is connected to the first capacitor C1 via the changeover switch S7, and is used for detecting deterioration of the insulation resistances Rp and Rn.

  The capacitor switching unit 26a2 controls the changeover switch S7 to control the first charging path (first and third paths P1 and P3) including the first capacitor C1 without including the second capacitor C2, and the second capacitor C2. Is switched between the second charging paths (the fourth and sixth paths P4 and P6) that include at least. The power supply monitoring unit 26c detects the voltage of the power supply in the first charging path based on the voltage of the capacitor charged in the first charging path or the second charging path, and detects the voltage of the insulation resistances Rp and Rn in the second charging path. Detect deterioration and monitor power supply status.

  This makes it possible to detect the power supply voltage and detect the deterioration of the insulation resistances Rp and Rn while simplifying the configuration of the power supply monitoring device 23 and suppressing an increase in cost.

  Note that, in the above-described embodiment, the positions and the numbers of the first capacitor C1, the second capacitor C2, the changeover switch S7, and the like are examples and are not limited. That is, the position of the first and second capacitors C1 and C2 and the like are different in the overall capacitance between the charging path for detecting the power supply voltage and the charging path for detecting the deterioration of the insulation resistances Rp and Rn. Anything can be used as long as it is possible.

  For example, in the voltage detection circuit unit 24, a switch connected in series with the first capacitor C1 and connected in parallel with the second capacitor C2 and the changeover switch S7 is newly provided. Then, the switch and the changeover switch S7 may be controlled to switch between a charging path including only the first capacitor C1 and a charging path including only the second capacitor C2.

  In the voltage detection circuit section 24, for example, the second capacitor C2 and the changeover switch S7 are connected in series to the first capacitor C1. Further, a switch connected in parallel to the first capacitor C1 and the changeover switch S7 is newly provided. Then, the switch and the changeover switch S7 may be controlled to switch between a charging path including the first and second capacitors C1 and C2 connected in series and a charging path including only the second capacitor C2.

  Further, in the above-described deterioration detection of the insulation resistances Rp and Rn, the voltage VRp and the voltage VRn of the capacitor C are compared with the threshold value Va, respectively, but the present invention is not limited to this. That is, for example, the deterioration of the insulation resistances Rp and Rn may be detected by adding the voltage VRp and the voltage VRn and comparing the added voltage with another predetermined threshold value.

  The timing at which the process of detecting the deterioration of the insulation resistances Rp and Rn is not limited to the above. That is, the timing at which the deterioration detection process is executed may be changed, for example, at the time of starting or stopping the vehicle, at predetermined time intervals or at predetermined traveling distances.

  Further, as described above, the control unit 26 can identify the failure of the changeover switch S7 when the voltage when the changeover switch S7 is turned on and the voltage when the changeover switch S7 is turned off are close values. If the acquired voltage is equal to or less than a second threshold value that can be set by setting a time during which almost no charge is accumulated when the changeover switch S7 is on, the control unit 26 determines that the changeover switch S7 is fixed to the on state. Is larger than the second threshold value, it is determined that the changeover switch S7 is stuck off.

  Therefore, the control unit 26 can execute the failure diagnosis of the changeover switch S7 that switches the capacity. Further, the control unit 26 can specify the failure content of the changeover switch S7. Further, a failure response according to the failure content of the changeover switch S7 can be executed, so that a functional loss can be avoided. Further, since the failure diagnosis of the changeover switch S7 can be performed using the circuit for switching the capacitance of the capacitor, a circuit for failure diagnosis is not required, and the circuit can be reduced in size and cost can be reduced.

  Further, in the above-described embodiment, an example has been described in which the switches S1 and S2 are turned on, the stack voltage of the first stack 12a is charged in the capacitor, and the state of the changeover switch S7 is determined. Not something. For example, instead of the switches S1 and S2, the switches S3 and S4 may be turned on to charge the capacitor with the stack voltage of the second stack 12b, and the state of the changeover switch S7 may be determined.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Charge / discharge system 10 Battery pack 12a 1st stack 12b 2nd stack 20 Power supply monitoring system 23 Power supply monitoring device 24 Voltage detection circuit unit 25 A / D conversion unit 26 Control unit 26a Charge / discharge path forming unit 26a1 First to sixth switches Control unit 26a2 Capacitor switching unit 26b Voltage detection unit 26c Power supply monitoring unit 26d Switch monitoring unit 30 Vehicle control device 40 Motor 50 Voltage converter 60 Fail safe relay C1 First capacitor C2 Second capacitor

Claims (5)

A power storage unit having a first capacitor connected to an insulated power supply, and a second capacitor connected to the power supply and connected to the first capacitor via a changeover switch;
Controlling the changeover switch to obtain a first voltage value of the power storage unit charged for a predetermined time using a first charging path including the first capacitor without including the second capacitor. 1 acquisition unit,
Controlling the changeover switch to obtain a second voltage value of the power storage unit charged during the predetermined time using a second charging path including the second capacitor and the first capacitor; Department and
A state determination device that determines a state of the changeover switch based on a difference between the first voltage value and the second voltage value.   The state determination device according to claim 1, wherein the second capacitor is connected in series to the changeover switch and is connected in parallel to the first capacitor.   The determination unit may include an on-fixed state in which the changeover switch cannot be turned off when a difference between the first voltage value and the second voltage value is equal to or less than a first threshold value and the first voltage value is less than a second threshold value. When the difference between the first voltage value and the second voltage value is equal to or less than a first threshold value and the first voltage value is equal to or more than a second threshold value, it is determined that the changeover switch cannot be turned on and is in an off-fixed state. The state determination device according to claim 1, wherein: The first acquisition unit, after discharging the voltage charged in the power storage unit, acquires the first voltage value by controlling the changeover switch,
2. The state determination device according to claim 1, wherein the second acquisition unit acquires the second voltage value by controlling the changeover switch after discharging the voltage charged in the power storage unit. 3. A state determination device having a power storage unit including a first capacitor connected to an insulated power supply and a second capacitor connected to the power supply and connected to the first capacitor via a changeover switch,
Controlling the changeover switch to obtain a first voltage value of the power storage unit charged for a predetermined time using a first charging path including the first capacitor without including the second capacitor. 1 acquisition process,
Controlling the changeover switch to obtain a second voltage value of the power storage unit charged during the predetermined time using a second charging path including the second capacitor and the first capacitor; Process and
A determination step of determining a state of the changeover switch based on a difference between the first voltage value and the second voltage value.

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