JP6668102B2 - Deterioration detection device and deterioration detection method - Google Patents

Description

  The present invention relates to a deterioration detection device and a deterioration detection 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. Note that the GND of the vehicle body may be described as a vehicle body GND, a vehicle body GND, a vehicle ground, or the like, as necessary.

  For example, a voltage (VRp) obtained by measurement (hereinafter sometimes referred to as Rp measurement) connected between the positive side (positive side) of the high-voltage battery and the GND of the vehicle body, and the negative side (negative side) of the high-voltage battery The insulation state is measured based on a voltage (VRn) obtained by a measurement (hereinafter, sometimes referred to as Rn measurement) connected between the vehicle side and the GND of the vehicle body.

JP 2012-181141 A JP-A-2002-291167 JP 2006-105824 A

  However, in the above technique, the GND of the vehicle body becomes unstable between the Rn measurement and the Rp measurement, and an error increases compared to the time when the measurement is stable. Therefore, when the next measurement is performed, erroneous detection occurs. There is. For example, a vehicle includes a Y capacitor for noise suppression and a so-called stray capacitance generated unintentionally (hereinafter, also referred to as a common capacitance in some cases). These change the potential of the GND of the vehicle body at the time of insulation measurement, so that extra charges are charged to the flying capacitor until the electric potential becomes stable, resulting in measurement errors.

  In other words, when describing the Rn measurement as an example, at the time of the Rn measurement, the body potential approaches the n-line and the body potential is in an unstable state. In this state, if the circuit is switched to the circuit at the time of Rp measurement, the charge voltage (VRp) is raised, which causes a measurement error.

  The disclosed technology has been made in view of the above, and has as its object to provide a deterioration detection device and a deterioration detection method that can reduce the influence of stray capacitance.

  In one aspect, a deterioration detection device disclosed in the present application is a deterioration detection device mounted on a vehicle, wherein a capacitor connected to an insulated power supply for charging / discharging, and a charge detecting deterioration of the insulation resistance of the power supply. A voltage detection unit that detects the voltage of the capacitor charged in the path, and a time period in which a difference value between successive voltages detected continuously by the voltage detection unit for a predetermined time is less than a threshold value, and / or An estimating unit for estimating a stray capacitance existing in the vehicle using an insulation resistance value of the vehicle.

  According to one embodiment of the deterioration detection device and the deterioration detection method disclosed in the present application, the influence of the stray capacitance can be reduced.

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 a voltage detection circuit unit of the power supply monitoring device. FIG. 4 is a diagram showing a charging path when detecting deterioration of the insulation resistance Rp on the positive electrode side of the battery pack. FIG. 5 is a diagram showing a discharge path for discharging the charged capacitor C. FIG. 6 is a diagram illustrating a charging path when detecting deterioration of the insulation resistance Rn on the negative electrode side of the battery pack. FIG. 7 is a diagram illustrating an example of estimating the stabilization time. FIG. 8 is a diagram illustrating an example of determining a threshold increase. FIG. 9 is a flowchart illustrating a part of the processing procedure of the deterioration detection processing. FIG. 10A is a flowchart illustrating a part of the processing procedure in the test mode. FIG. 10B is a flowchart illustrating a part of the processing procedure in the test mode. FIG. 11 is a time chart illustrating a part of the processing procedure of the deterioration detection processing.

  Hereinafter, embodiments of a deterioration detection device and a deterioration detection 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: Hybrid Electric Vehicle), an electric vehicle (EV: Electric Vehicle), and a fuel cell vehicle (FCV: Fuel Cell Vehicle) 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 can monitor the individual voltages of the plurality of battery cells 13 and also monitor 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.

  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. The monitoring of the state of charge of the battery pack 10 may be performed by directly measuring the stack voltage or by directly measuring the voltage (block voltage) of a block that is a set of a plurality of cells.

  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. In FIG. 2, the satellite substrate 22, the communication line L1, and the like are omitted. FIG. 2 shows one of the plurality of blocks 11 for convenience of understanding. Hereinafter, one of the two battery stacks 12 in the block 11 is referred to as a “first stack 12a” and the other is referred to as a “first stack 12a”. 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.

  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.

  By the way, since the process of detecting the voltage of each of the stacks 12a and 12b is desirably completed in a relatively short time, the capacitance of the capacitor C used for voltage detection is set so that it can be charged in a short time. A relatively small one is preferred.

  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 C, 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.

  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. The processing is performed with the capacitance.

  Note that 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 2.0 μF, which is 20 times the stray capacitance of the vehicle. In such a case, the capacitance of the first capacitor C1 is, for example, about 0.7 μF. As described above, the capacitance of the second capacitor C2 is larger than the capacitance of the first capacitor C1.

  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 and second capacitors C1 and C2 are used for detecting deterioration of the insulation resistances Rp and Rn.

  Here, as shown in FIG. 3, the circuit of the voltage detection circuit unit 24 is provided with the insulation resistance Rp on the positive electrode side and the insulation resistance Rn on the negative electrode side 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. 4 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. 5 is a diagram illustrating a discharge path for discharging the charged capacitor C, and FIG. 6 is a diagram illustrating a charging path when detecting deterioration of the insulation resistance Rn on the negative electrode side of the battery pack 10. is there.

  First, when detecting deterioration of the insulation resistance Rp on the positive electrode side, as shown in FIG. 4, 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 first path P1 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 first path P1 is hardly conductive, and when the insulation resistance Rp is deteriorated and the resistance value is reduced, the first path P1 is It becomes conductive.

  Then, after a predetermined time has passed since the first path P1 was formed, the voltage of the capacitor C is discharged. Specifically, as shown in FIG. 5, the fourth switch S4 is turned off and the sixth switch S6 is turned on. As a result, a second path P2 serving as a discharge path is formed in the voltage detection circuit section 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. 6, 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 third path P3 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 third path P3 is hardly conductive, and when the insulation resistance Rn is deteriorated and the resistance value is reduced, the third path P3 is It becomes conductive.

  Then, after a predetermined time has elapsed since the third path P3 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.

  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.

  By the way, in the above-described deterioration detection of the insulation resistances Rp and Rn, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 connected to the positive electrode side and the negative electrode side of each battery stack 12, respectively. Is operating normally. That is, it is preferable to confirm the state of each of the switches on the high voltage side before performing the voltage detection and the deterioration detection.

  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 charging path forming unit 26a, a discharging path forming unit 26b, a voltage detecting unit 26c, a deterioration detecting unit 26d, and a common capacity estimating unit 26e. As described in FIG. 4 and FIG. 6, the charging path forming unit 26a controls the first to sixth switches S1 to S6 and the changeover switch S7 to change the first path P1 and the third path P3, which are charging paths. Form. As described with reference to FIG. 5, the discharge path forming unit 26b controls the first to sixth switches S1 to S6 and the changeover switch S7 to form a second path P2 that is a discharge path. The charging path forming unit 26a and the discharging path forming unit 26b form a charging path and a discharging path according to instructions from the voltage detecting unit 26c, the deterioration detecting unit 26d, the common capacity estimating unit 26e, and the like.

  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. The charging path forming unit 26a and the discharging path forming unit 26b form a charging path or a discharging path by reading a switching pattern from the storage unit at an appropriate timing.

  When the discharge path is formed by the discharge path forming section 26b, the voltage detecting section 26c detects the charged voltage of the capacitor C or the like via the A / D converter 25. The voltage detector 26c detects the voltages VRp and VRn described above. The voltage detection unit 26c outputs the detected voltages VRp and VRn to the deterioration detection unit 26d, the common capacity estimation unit 26e, the vehicle control device 30, and the like.

  The deterioration detection unit 26d detects deterioration of the insulation resistances Rp and Rn based on the voltages VRp and VRn of the capacitor C. 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 deterioration detection unit 26d compares the voltage VRp and the voltage VRn with a threshold Va set to a relatively low value.

  When the voltage VRp of the capacitor C becomes equal to or higher than the threshold value Va, the deterioration detection unit 26d 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 deterioration detection unit 26d determines that the insulation resistance Rp is not deteriorated, in other words, the insulation resistance Rp is normal.

  Similarly, the deterioration detection unit 26d 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 lower 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.

  As another example, the deterioration detection unit 26d generates a charging path or the like at different times, acquires the voltage VRn twice, and sets the two as VRn1 and VRn2. Similarly, the deterioration detection unit 26d generates a charging path and the like at different times, acquires the voltage VRp twice, and sets the voltages to VRp1 and VRp2. Then, the deterioration detecting unit 26d calculates the first sum of the voltage values (V1 = VRn1 + VRp1), and calculates the second sum of the voltage values (V2 = VRn2 + VRp2).

  If ΔV (= V2−V1) is equal to or larger than the threshold value, the deterioration detection unit 26d can detect that the insulation is abnormal, and if ΔV (= V2−V1) is smaller than the threshold value, it can determine normal. By doing so, it is possible to execute the deterioration determination in which the influence of the common capacitance is reduced.

  Then, the deterioration detection unit 26d 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.

  The common capacity estimating unit 26e calculates the stabilization time of the common capacity existing in the entire vehicle by using the insulation resistance (Rp, Rn) of the vehicle, and sets a waiting time between the Rn measurement and the Rp measurement. Specifically, the common capacitance estimating unit 26e measures the above stabilization time as a test mode before starting abnormality detection of the insulation resistance (Rp, Rn), and applies the insulation resistance (Rp , Rn).

  For example, the common capacitance estimating unit 26e measures the voltage VRn a plurality of times, and calculates the time during which the difference value of each measurement is less than the threshold, that is, the time during which the common capacitance is stabilized. Similarly, the common capacitance estimating unit 26e measures the voltage VRp a plurality of times, and calculates the time during which the difference value of each time is less than the threshold, that is, the time during which the common capacitance is stabilized. Then, the common capacity estimating unit 26e sets the longer one of the calculated two stabilization times as the waiting time, and causes the Rn measurement and the Rp measurement to be executed.

  FIG. 7 is a diagram illustrating an example of estimating the stabilization time. A description will be given of an example of Rp measurement as an example. For example, as shown in FIG. 7, the difference ΔV1 between VRp0 at time t0 and VRp1 at time t1 and the difference ΔV2 between VRp1 at time t1 and VRp2 at time t2 have substantially the same magnitude. In some cases, it can be estimated that the common capacitance is stable at least at time t1. Therefore, the common capacity estimating unit 26e sets the time t1 to a stable time.

  As described above, since the common capacitance estimating unit 26e can detect the abnormality detection of the insulation resistance after calculating the stabilization time, the stabilization time can be dynamically changed. Note that the timing for calculating the stabilization time may be, for example, periodically executed, may be always executed before detecting the insulation resistance abnormality, or may be executed after a plurality of insulation resistance abnormality detections, It can be set arbitrarily.

  Further, the common capacitance estimating unit 26e can estimate the common capacitance that will actually exist and dynamically change the threshold value used for the insulation resistance abnormality detection. For example, the common capacity estimating unit 26e calculates the resistance of the vehicle (insulation resistance + charging resistance in the circuit) by using the calculation formula of Expression (1), and estimates by the time constant using the calculation result and the stabilization time. Can also be performed.

  Vc in the equation (1) is “Vc = second VRn measurement result in test mode (VRn1) + second VRp measurement result in test mode (VRp1)”, and Vo is “Vo = test mode Of the first VRn measurement in the test mode (VRn0) + the first VRn measurement result in the test mode (VRn0) ”. VB is the battery voltage, and R is the insulation resistance plus the charging resistance in the circuit.

  Then, the common capacitance estimating unit 26e calculates the common capacitance Cs by substituting the calculated R and the measured stabilization time t into “t = Cs × R × 7τ” (τ is a time constant). After that, the common capacitance estimating unit 26e determines the increment of the threshold from the common capacitance Cs and the resistance R, and notifies the deterioration detecting unit 26d and the like. As a result, the deterioration detection unit 26d updates the threshold and detects the deterioration of the insulation resistance using the new threshold.

  FIG. 8 is a diagram illustrating an example of determining a threshold increase. The horizontal axis of FIG. 8 is the vehicle insulation resistance R, and the vertical axis is the increase (V) of the threshold. The common capacitance estimating unit 26e selects a graph corresponding to the estimated common capacitance Cs from the graph of FIG. 8, and specifies a threshold increase corresponding to the resistance R in the graph. Then, the common capacity estimating unit 26e notifies the deterioration detecting unit 26d and the like of the specified increase in the threshold value. The method using the graph is an example, and a calculation formula for calculating the increase from the common capacitance and the resistance may be defined in advance, and the calculation may be performed using the calculation formula.

  Note that the threshold may be changed when the stabilization time exceeds the threshold.

<3. Specific operation of deterioration detection processing>
Next, a specific operation of the deterioration detection process performed by the power supply monitoring system 20 configured as described above will be described with reference to FIGS. 9, 10A, and 10B. FIG. 9 is a flowchart showing a part of the processing procedure of the deterioration detection processing. FIGS. 10A and 10B are flowcharts showing a part of the processing procedure of the test mode.

  As shown in FIG. 9, when the voltage of the capacitor C is lower than the threshold value (for example, near 0 V) (Step S101: Yes), the power supply monitoring device 23 turns on the changeover switch S7 (Step S102), and the voltage of the capacitor C Is greater than or equal to the threshold value (step S101: No), the discharge process is executed (step S103), and then the changeover switch S7 is turned on (step S102).

  Subsequently, the power supply monitoring device 23 executes the test mode (step S104), and when the test mode is completed, turns on the first switch S1 and the sixth switch S6 (step S105), and charges the capacitor C for x seconds. , Rn measurement (step S106).

  Then, after turning off the first switch S1 and the sixth switch S6 (step S107), the power supply monitoring device 23 turns on the fifth switch S5 and the sixth switch S6 (step S108), and obtains VRn1 (step S108). Step S109).

  Subsequently, the power supply monitoring device 23 turns off the fifth switch S5 and the sixth switch S6 (step S110), turns on the first switch S1 and the sixth switch S6 (step S111), and resets the capacitor C again. Charge for x seconds, and execute Rn measurement (step S112).

  Thereafter, the power supply monitoring device 23 turns off the first switch S1 and the sixth switch S6 (step S113), turns on the fifth switch S5 and the sixth switch S6 (step S114), and acquires VRn2 (step S114). Step S115).

  Subsequently, the power supply monitoring device 23 turns off the fifth switch S5 and the sixth switch S6 (step S116), and waits for a predetermined time (stabilization time) set in the test mode (step S117).

  Then, after waiting for a predetermined time (stabilization time) set in the test mode, the power supply monitoring device 23 turns on the fourth switch S4 and the fifth switch S5 (step S118), and charges the capacitor C for x seconds. , Rp measurement is executed (step S119).

  Then, after turning off the fourth switch S4 and the fifth switch S5 (step S120), the power supply monitoring device 23 turns on the fifth switch S5 and the sixth switch S6 (step S121), and acquires VRp1 (step S121). Step S122).

  Subsequently, the power monitoring device 23 turns off the fifth switch S5 and the sixth switch S6 (step S123), turns on the fourth switch S4 and the fifth switch S5 (step S124), and resets the capacitor C again. Charge for x seconds, and execute Rp measurement (step S125).

  Then, after turning off the fourth switch S4 and the fifth switch S5 (step S126), the power supply monitoring device 23 turns on the fifth switch S5 and the sixth switch S6 (step S127), and obtains VRp2 (step S127). Step S128).

  Then, the power supply monitoring device 23 calculates V1 = VRn1 + VRp1 and V2 = VRn2 + VRp2 (step S129), and calculates ΔV = V2-V1 (step S130).

  Thereafter, if ΔV is equal to or larger than the threshold value (Step S131: Yes), the power supply monitoring device 23 detects the occurrence of an insulation abnormality (Step S132). If ΔV is smaller than the threshold value (Step S131: No), it is determined to be normal. (Step S133). Here, the threshold value is a predetermined value or a value obtained by adding the increment calculated in the test mode to the value.

  Further, in parallel with the determination of the insulation abnormality, the power supply monitoring device 23 turns off the fifth switch S5 and the sixth switch S6 (step S134), and executes a discharge process (step S135). Note that the VRn measurement and the VRp measurement are in no particular order.

  Next, the test mode will be described. As shown in FIG. 10A, when the voltage of the capacitor C is lower than the threshold value (for example, near 0 V) (Step S201: Yes), the power supply monitoring device 23 turns on the changeover switch S7 (Step S202), and the voltage of the capacitor C Is greater than or equal to the threshold value (step S201: No), the discharge process is executed (step S203), and then the changeover switch S7 is turned on (step S202).

  Subsequently, the power supply monitoring device 23 turns on the first switch S1 and the sixth switch S6 (step S204), charges the capacitor C for x seconds, and executes Rn measurement (step S205).

  Thereafter, the power supply monitoring device 23 turns off the first switch S1 and the sixth switch S6 (step S206), turns on the fifth switch S5 and the sixth switch S6 (step S207), and obtains VRn0 (step S207). (Step S208), the fifth switch S5 and the sixth switch S6 are turned off (Step S209).

  Further, the power supply monitoring device 23 acquires the VRn1 by executing the same processing as the steps S204 to S209 (steps S210 to S215) and acquires the VRn2 (steps S216 to S221).

  Thereafter, the power supply monitoring device 23 calculates ΔV1 = VRn1−VRn0 and ΔV2 = VRn2−VRn1 (step S222), and compares the difference value of ΔV2−ΔV1 with a threshold (step S223).

  Here, when the difference value is equal to or greater than the threshold value (step S223: No), the power supply monitoring device 23 substitutes VRn1 for VRn0, that is, sets the value of VRn1 to VRn0 (step S224), and it takes time to measure VRn1. The counted time is counted (Step S225), and Step S207 and the subsequent steps are repeated.

  On the other hand, when the difference value is smaller than the threshold value (Step S223: Yes), the power supply monitoring device 23 holds VRn0 and VRn1 (Step S226), and measures the time taken to measure VRn1, in other words, from the start of processing. The time (t) until the VRn1 measurement is held (step S227).

  Subsequently, as shown in FIG. 10B, the power supply monitoring device 23 turns on the fourth switch S4 and the fifth switch S5 (step S228), charges the capacitor C for x seconds, and executes Rp measurement (step S229). ).

  Then, after turning off the fourth switch S4 and the fifth switch S5 (step S230), the power supply monitoring device 23 turns on the fifth switch S5 and the sixth switch S6 (step S231), and acquires VRp0 (step S231). (Step S232), the fifth switch S5 and the sixth switch S6 are turned off (Step S233).

  Further, the power supply monitoring device 23 obtains VRp1 by executing the same processing as in steps S228 to S233 (steps S234 to S239) and obtains VRp2 (steps S240 to S245).

  Thereafter, the power supply monitoring device 23 calculates ΔV1 = VRp1−VRp0 and ΔV2 = VRp2−VRp1 (step S246), and compares the difference value of ΔV2−ΔV1 with a threshold (step S247).

  Here, when the difference value is equal to or larger than the threshold value (Step S247: No), the power supply monitoring device 23 substitutes VRp1 for VRp0, that is, sets the value of VRp1 to VRp0 (Step S248), and takes a time to measure VRp1. The counted time is counted (step S249), and the steps after step S231 are repeated.

  On the other hand, if the difference value is smaller than the threshold value (step S247: Yes), the power supply monitoring device 23 holds VRp0 and VRp1 (step S250), and measures the time taken to measure VRp1, ie, from the start of processing. The time (t) until the VRp1 measurement is held (step S251).

  Thereafter, the power supply monitoring device 23 estimates the common capacity (step S252), compares the time held in S227 with the time held in S251, and determines the longer time as the waiting time (stabilization time) (step S252). S253). Note that the power supply monitoring device 23 also determines an increase in the threshold value in step S252. The order of the VRn measurement and the VRp measurement is not specified.

<4. Time chart>
FIG. 11 is a time chart illustrating a part of the processing procedure of the deterioration detection processing. Here, an example in which the changeover switch S7 is turned off will be described as an example.

  As shown in FIG. 11, when the process is started, the power supply monitoring device 23 controls various switches, measures VRn0 after t0 from the start of the process, measures VRn1 after t1 from the start of the process, VRn2 is measured t2 after the processing is started.

  Here, when the difference between VRn0 and VRn1 is large, the power supply monitoring device 23 can determine that the difference occurs due to the influence of the common capacitance from time t0 to t1, and thus the common capacitance is still stable at time t1. It is determined that it has not been performed. Then, when the difference between VRn1 and VRn2 is small, the power supply monitoring device 23 can determine that the influence of the common capacitance is small from time t1 to t2, and thus determines that the common capacitance is stable after time t1. I do.

  Therefore, the power supply monitoring device 23 determines the time t1 as a candidate for the waiting time (stabilization time). In addition, the power supply monitoring device 23 performs the same process on the VRp measurement based on the start of the VRp measurement, and determines the time t2 as a candidate for the waiting time (stabilization time). Then, the power supply monitoring device 23 sets the longer time as the waiting time so as to perform control so as not to be more affected by the common capacitance in both the VRn measurement and the VRp measurement.

<5. Effects and Modifications>
As described above, since the common capacitance existing in the vehicle can be estimated using the amount of change in the voltage of the capacitor C and the insulation resistance value of the vehicle, the time at which the vehicle body GND stabilizes can be predicted. In addition, the effect of the common capacitance can be reduced. In addition, since the waiting time at the time of switching between the VRn measurement and the VRp measurement can be dynamically changed according to the actually measured value, it is possible to follow the aging of the circuit and the like. Furthermore, since it can follow the aging of the circuit and the like, the influence of the stray capacitance can be reduced and the reduction accuracy can be maintained.

  Further, even when the waiting time at the time of switching between the VRn measurement and the VRp measurement becomes longer than the threshold value, the threshold value for the deterioration determination can be dynamically changed. And the deterioration of the determination accuracy can be suppressed.

  Further, in the above-described embodiment, an example in which VRn or VRp is obtained continuously for a predetermined time and the time during which the difference between successive VRn or VRp is less than the threshold, in other words, the time during which the difference value (change amount) converges, is specified. Although described, the present invention is not limited to this. For example, the voltage value of the time specified as the stabilization time or the difference value determined as the stabilization time in the previous test mode may be held, and these may be used as the threshold. Specifically, a time when the difference between VRn0 and the held voltage value is less than a threshold value is specified, or a time when the difference between ΔV and the held difference value is less than the threshold value is specified. I do.

  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 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 path formation unit 26b Discharge path formation unit 26c Voltage detection Unit 26d Degradation detection unit 26e Common capacity estimation unit 30 Vehicle control device 40 Motor 50 Voltage converter 60 Fail safe relay C1 First capacitor C2 Second capacitor

Claims (4)

In a deterioration detection device mounted on a vehicle,
A capacitor connected to an insulated power supply for charging and discharging;
A voltage detection unit that detects a voltage of the capacitor charged in a charging path that detects deterioration of insulation resistance of the power supply;
A stray capacitance existing in the vehicle using a time during which a difference value between successive voltages detected continuously for a predetermined time by the voltage detection unit is less than a threshold value, and / or an insulation resistance value of the vehicle. an estimation unit for estimating,
Wherein comparing the threshold value and a voltage with a preset voltage value of the capacitor detected by the voltage detection unit, possess a degradation detecting unit for detecting deterioration of the insulation resistance of the power supply based on the comparison result,
The estimating unit may be configured such that a difference value between a first voltage acquired after a first time after the measurement of the voltage is started and a second voltage acquired after a second time is less than the threshold. In this case, a time until the stray capacitance stabilizes is determined as the first time . The voltage detection unit is configured to switch between a first discharge path connecting the positive electrode of the power supply and the ground of the vehicle and a second discharge path connecting the negative electrode of the power supply and the ground of the vehicle. the deterioration detecting apparatus according to claim 1, characterized in that switching from the lapse of the first time. The estimating unit determines an increase in the threshold from the estimated stray capacitance, the first time, and the insulation resistance value of the vehicle, and determines a new threshold obtained by adding the determined increase to the power supply. 2. The deterioration detection device according to claim 1 , wherein the threshold value is set to a threshold value used for detecting insulation resistance deterioration. The deterioration detection device mounted on the vehicle,
A voltage detection step of detecting the voltage of the capacitor, wherein the capacitor connected to the insulated power supply for charging and discharging is charged by a charging path for detecting the deterioration of the insulation resistance of the power supply,
A stray capacitance existing in the vehicle using a time during which a difference value between successive voltages detected continuously for a predetermined time in the voltage detection step is less than a threshold value, and / or an insulation resistance value of the vehicle. and estimating step of estimating a,
A deterioration detection step of comparing the voltage of the capacitor detected in the voltage detection step with a threshold value that is a preset voltage value, and detecting deterioration of the insulation resistance of the power supply based on the comparison result;
Including
In the estimating step, a difference value between a first voltage acquired after a first time after the measurement of the voltage is started and a second voltage acquired after a second time is less than the threshold. And determining the time until the stray capacitance stabilizes as the first time .

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