JP6504855B2 - Deterioration detection device and deterioration detection method - Google Patents

Description

  The present invention relates to a deterioration detection device and a deterioration detection method.

  Conventionally, in a vehicle such as a hybrid car and an electric car, for example, a power supply for supplying power to a motor as a power source is provided. The power supply is configured to be insulated from the vehicle body, and a device for monitoring the insulation state of the power supply, in other words, a device for detecting deterioration of the insulation resistance of the power supply is known (e.g. Reference 1).

  In the above-described prior art, the deterioration of the insulation resistance of the power supply is detected using a flying capacitor method. Specifically, in the prior art, the capacitor is energized to charge the capacitor through the insulation resistance, and the deterioration of the insulation resistance of the power supply is detected based on the voltage of the charged capacitor.

JP, 2014-20914, A

  However, the vehicle has stray capacity that is not intended at design time. Therefore, there is a possibility that the voltage of the capacitor can not be accurately detected under the influence of the stray capacitance, and the accuracy of the detection of the deterioration of the insulation resistance may be lowered.

  Therefore, for example, a resistor or switch for measuring stray capacitance is added to the charging path connecting the power supply, the capacitor, and the insulation resistor to measure the stray capacitance, and the power supply is isolated based on the measured stray capacitance and the voltage of the capacitor. A method of detecting deterioration of resistance can be considered. However, with the above-described method, the addition of an element such as a resistor complicates the configuration of the degradation detection device and may increase the cost.

  The present invention has been made in view of the above, and it is possible to estimate stray capacitance with a simple configuration, and to improve the accuracy of detection of degradation of insulation resistance of a power supply, and a degradation detection device, and It aims at providing a degradation detection method.

In order to solve the above problems and achieve the object, the present invention includes, in a degradation detection device, a capacitor, a voltage detection resistor, a voltage detection unit, a stray capacitance estimation unit, and a degradation detection unit. The capacitor is connected to the isolated power supply to charge and discharge. The voltage detection resistor is provided in the charging path for detecting the deterioration of the insulation resistance of the power supply, and one end side is connected to the ground point. The voltage detection unit detects the voltage of the capacitor and the voltage of the detection point on the other end side of the voltage detection resistor after the charge path for detecting the deterioration of the insulation resistance of the power supply is formed. The floating capacity estimation unit estimates the floating capacity of the charge path based on the voltage at the detection point. The deterioration detection unit detects the deterioration of the insulation resistance of the power supply based on the voltage of the capacitor and the stray capacitance. The floating capacity estimating unit may be configured to calculate the voltage of the detection point immediately after the charge path is formed and the voltage of the detection point after a predetermined time has elapsed since the charge path was formed. The voltage change rate at the detection point is calculated, and the stray capacitance is estimated based on the voltage change rate.

  According to the present invention, it is possible to estimate the stray capacitance while having a simple configuration, and by using the estimated stray capacitance, it is possible to improve the accuracy of detection of deterioration of the insulation resistance of the power supply.

FIG. 1 is a block diagram showing a configuration example of a charge and discharge system including the deterioration detection device according to the first embodiment. FIG. 2 is a block diagram showing a configuration example of the deterioration detection device. FIG. 3 is a diagram showing a configuration example of the voltage detection circuit unit. FIG. 4 is a diagram showing a charge path for charging the capacitor with the voltage of the first stack. FIG. 5 is a diagram showing a discharge path for discharging the charged capacitor. FIG. 6 is a diagram showing a charge path for charging the capacitor with the voltage of the second stack. FIG. 7 is a diagram showing a charge path when detecting deterioration of the insulation resistance on the positive electrode side of the assembled battery. FIG. 8 is a diagram showing a charge path when detecting deterioration of the insulation resistance on the negative electrode side of the assembled battery. FIG. 9 is a flowchart showing a part of the processing procedure of processing executed by the battery monitoring system. FIG. 10 is a block diagram showing a configuration example of a control unit of the deterioration detecting device according to the second embodiment. FIG. 11 is a graph for explaining the floating capacity estimation process performed by the floating capacity estimation unit. FIG. 12 is a graph for explaining the correction processing performed by the deterioration detection unit. FIG. 13 is a flowchart showing a part of the processing procedure of processing executed by the battery monitoring system according to the second embodiment.

  Hereinafter, with reference to the accompanying drawings, embodiments of the degradation detection apparatus and the degradation detection method disclosed in the present application will be described in detail. Note that the present invention is not limited by the embodiments described below.

First Embodiment
<1. Configuration of charge and discharge system>
FIG. 1 is a block diagram showing a configuration example of a charge and discharge system including the deterioration detection device according to the first embodiment. The charge and discharge system 1 is mounted on vehicles, such as a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), an electric vehicle (EV: Electric Vehicle), and a fuel cell electric vehicle (FCV: Fuel Cell Vehicle), not shown. The charge and discharge system 1 is a system that charges and discharges a power supply that supplies electric power to a motor that is a power source of a vehicle.

  Specifically, the charge and discharge system 1 includes a battery pack 10, a battery monitoring system 20, a vehicle control device 30, a motor 40, a voltage converter 50, and a failsafe relay 60. Further, the battery monitoring system 20 includes a plurality of satellite substrates 22 each having a monitor IC (Integrated Circuit) 21 or the like, and a deterioration detection device 23.

  The battery assembly 10 is a power supply (battery) insulated from a vehicle body (not shown), and is constituted by 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 stack 12, and the battery cells 13 are not limited to those described above or illustrated. In addition, as the above-described assembled battery 10, for example, a lithium ion secondary battery, a nickel hydrogen secondary battery, or the like 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 the satellite substrate 22. Then, 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 second monitor ICs 21b, and the first and second monitor ICs 21a and 21b respectively detect voltages of the battery cells 13 of one battery stack 12 minutes.

  The deterioration detection device 23 detects the deterioration of the insulation resistance (described later) of the battery 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 is lowered to cause the leakage of the assembled battery 10.

  The deterioration detection device 23 also has a function of monitoring the individual voltages of the plurality of battery cells 13 and monitoring the voltage of each battery stack 12. That is, the deterioration detection device 23 monitors the charge state of the assembled battery 10.

  Specifically, the deterioration detection device 23 transmits a voltage detection request to the monitor IC 21 to detect individual voltages of the plurality of battery cells 13, and receives the detection result via the communication line L1. , Monitor the voltage of the battery cell 13. Further, the deterioration detection device 23 directly measures the stack voltage by charging the voltage of the battery stack 12 (hereinafter sometimes referred to as “stack voltage”) to a capacitor to be described later via the conducting wire L2, The charge state of the battery 10 is monitored.

  It is preferable that the deterioration detection device 23 also have a function of determining whether the monitor IC 21 is operating normally. Specifically, for example, the deterioration detection device 23 compares the stack voltage obtained by adding the individual voltages of the battery cells 13 received from the monitor IC 21 with the stack voltage detected directly, and the difference between the two is acceptable. When it 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 deterioration detection device 23 may disconnect the fail-safe relay 60, for example, so that charging / discharging of the battery cell 13 is not performed.

  The voltage converter 50 includes a boost converter 51 (see FIG. 3) and an inverter (not shown), and boosts the voltage output from the assembled battery 10 serving as a power source and converts the voltage from direct current to alternating current. In FIG. 1, the deterioration detection device 23 and the voltage converter 50 are illustrated separately, but this is an exemplification and is not limited. For example, the deterioration detection device 23 includes the voltage converter 50. It may be configured.

  The vehicle control device 30 controls the vehicle by charging and discharging the assembled battery 10 in accordance with the charged state of the assembled battery 10. Specifically, the vehicle control device 30 supplies the voltage of the assembled battery 10, which is boosted by the voltage converter 50 and converted into an alternating current, to the motor 40 to drive the motor 40. As a result, the battery pack 10 is discharged.

  In addition, although the motor 40 was mentioned as an electric load to which a voltage is supplied from the voltage converter 50 in the above, this is an illustration and it is not limited, for example, an air conditioner, a lighting, audio equipment, car navigation Other electrical components such as a system may be used.

  The vehicle control device 30 converts the voltage generated by the regenerative braking of the motor 40 by the voltage converter 50 from an alternating current to a direct current voltage, and supplies the voltage to the assembled battery 10. As a result, the battery pack 10 is charged. Thus, the vehicle control device 30 monitors the voltage of the assembled battery 10 based on the charge state of the assembled battery 10 acquired from the deterioration detection device 23, and executes control according to the monitoring result.

<2. Configuration of Deterioration Detection Device>
Next, the configuration of the deterioration detection device 23 will be described. FIG. 2 is a block diagram showing a configuration example of the deterioration detection device 23. In addition, in FIG. 2, the satellite board | substrate 22, the communication line L1, etc. are abbreviate | omitted. Further, in FIG. 2, one of the plurality of blocks 11 is shown for convenience of understanding, and in the following, one of the two battery stacks 12 in the block 11 is referred to as “first stack 12 a”, the other May be described as “second stack 12 b”.

  The deterioration detection device 23 is, for example, an electronic control unit (ECU: Electronic Control Unit), 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 detecting each stack voltage, detecting deterioration of the insulation resistance, and the like. Here, the voltage detection circuit unit 24 will be described in detail with reference to FIG.

  FIG. 3 is a view showing a configuration example of the voltage detection circuit unit 24. As shown in FIG. As shown in FIG. 3, the voltage detection circuit unit 24 includes a capacitor C1, first switches S1 to sixth switches S6, and first to seventh resistors R1 to R7. In addition, the battery assembly 10 includes the insulation resistance Rp on the positive electrode side and the insulation resistance Rn on the negative electrode side.

  In the voltage detection circuit unit 24, a flying capacitor method is applied, and as described later, after charging the capacitor C1 with the voltage of each stack 12a, 12b, the voltage of the capacitor C1 is detected as the voltage of each stack 12a, 12b. ing.

  Specifically, the voltage detection circuit unit 24 is divided into a charge side circuit and a discharge side circuit via the capacitor C1. The charge side circuit is a portion including the stacks 12a and 12b of the battery pack 10 and the capacitor C1 connected to each other and including a path for charging the voltage of each stack 12a and 12b to the capacitor C1. The discharge side circuit is a portion including a path for discharging the voltage charged in the capacitor C1.

  Then, by controlling the on / off of each of the switches S1 to S6, charging and discharging of the capacitor C1 are controlled. For example, a solid state relay (SSR) can be used as each of the switches S1 to S6 described above, but the present invention is not limited to this. The first resistor R1 to the seventh resistor R7 are resistors used for voltage detection of the capacitor C1.

  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 C1. That is, both ends of the capacitor C1 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 C1, and the negative electrode side of the first stack 12a and the capacitor C1 are provided. A second resistor R2 and a second switch S2 are provided in series between the two.

  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 C1, and the negative electrode side of the second stack 12b and the capacitor C1 are provided. A fourth resistor R4 and a fourth switch S4 are provided in series between the two.

  In the discharge side circuit of the voltage detection circuit unit 24, a fifth switch S5 is provided in a path on the positive electrode 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 C1. A resistor R5 is provided. Further, a sixth switch S6 is provided in the 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 C1.

  The other end of the fifth switch S5 is connected to the A / D converter 25, and is branched halfway and 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. The vehicle body GND is an example of a ground point, and the voltage at the ground point may be hereinafter referred to as a "body voltage".

  The A / D conversion unit 25 converts an analog value indicating the voltage at the detection point A of the voltage detection circuit unit 24 into a digital value, and converts the converted digital value to the control unit 26 (precisely, a voltage detection unit or the like described later) Output to

  Here, charging and discharging of the 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 showing a charging path for charging the capacitor C1 with the voltage of the first stack 12a. FIG. 5 is a view showing a discharge path for discharging the charged capacitor C1, and FIG. 6 is a view showing a charge path for charging the capacitor C1 with the voltage of the second stack 12b.

  In the deterioration detection device 23, the capacitor C1 is charged for each of the first and second stacks 12a and 12b. First, an example in which the 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. 4, the first switch S1 and the second switch S2 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 negative electrode side of the first stack 12a via the first resistor R1, the first switch S1, the fifth resistor R5, the capacitor C1, the second switch S2 and the second resistor R2. Connected That is, a first path P1 connecting the first stack 12a and the capacitor C1 is formed, and the capacitor C1 is charged with the first stack voltage.

  Then, after a predetermined time has elapsed since the formation of the first path P1, the voltage of the 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, in the voltage detection circuit unit 24, a second path P2 which is a discharge path is formed. Since the A / D conversion unit 25 is connected to the other end of the fifth switch S5, when the second path P2 is formed, the voltage of the capacitor C1 (that is, the first stack voltage) becomes the A / D conversion unit 25. Is input to The A / D converter 25 converts an analog value input at the moment when the fifth and sixth switches S5 and S6 are turned on into a digital value and outputs the digital value to the controller 26. Thereby, the first stack voltage is detected.

  Next, an example will be described in which the capacitor C1 is charged with the voltage of the second stack 12b (hereinafter sometimes referred to as "second stack voltage"). As shown in FIG. 6, the third switch S3 and the fourth switch S4 are turned on, and the other switches S1, S2, S5, and S6 are turned off.

  Thus, the positive electrode side of the second stack 12b is connected to the negative electrode side of the second stack 12b via the third resistor R3, the third switch S3, the fifth resistor R5, the capacitor C1, the fourth switch S4, and the fourth resistor R4. Connected That is, a third path P3 connecting the second stack 12b and the capacitor C1 is formed, and the capacitor C1 is charged with the second stack voltage.

  Then, after a predetermined time has elapsed since 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, so that the capacitor C1 is turned on. The voltage is discharged (see FIG. 5).

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

  Thus, the first stack voltage and the second stack voltage can be detected by switching the path on the discharge side and the path on the charge side to charge and discharge the capacitor C1.

  Further, in the circuit of the voltage detection circuit section 24, as shown in FIG. 3, 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 are provided. In addition, although each of these insulation resistances Rp and Rn has shown the synthetic | combination resistance of the mounted resistance and the resistance which represented the insulation with respect to the vehicle body GND virtually, here, the mounted resistance and the virtual resistance It does not matter which one.

  The resistance value of each of the insulation resistances Rp and Rn is set to a sufficiently large value, for example, several M.OMEGA. So as to hardly conduct electricity at normal times. However, in the abnormal state where the insulation resistances Rp and Rn are deteriorated, for example, the battery pack 10 is short-circuited with the vehicle body GND or the like, or lowered to a resistance value to the extent that the current flows.

  Here, charging and discharging of the capacitor C1 performed to detect deterioration of the insulation resistances Rp and Rn of the assembled battery 10 will be described with reference to FIGS. 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 assembled battery 10. FIG. 8 is a diagram showing a charging path when detecting the deterioration of the insulation resistance Rn on the negative electrode side of the assembled battery 10.

  First, when deterioration of the insulation resistance Rp on the positive electrode side is detected, as shown in FIG. 7, the fourth switch S4 and the fifth switch S5 are turned on, and the other switches S1 to S3 and S6 are turned off. Thereby, the positive electrode side of the first stack 12a is via the insulation resistance Rp, the sixth resistance R6, the fifth switch S5, the fifth resistance R5, the capacitor C1, the fourth switch S4, the fourth resistance R4 and the second stack 12b. Thus, it is connected to the negative electrode side of the first stack 12a.

  That is, a fourth path P4 is formed, which connects the first and second stacks 12a and 12b and the capacitor C1 via the insulation resistance Rp on the positive electrode side. At this time, when the resistance value of the insulation resistance Rp is normal, the fourth path P4 hardly conducts, and when the insulation resistance Rp is deteriorated and the resistance value is lowered, the fourth path P4 is It will be conducted.

  Then, after a predetermined time has elapsed since the formation of the fourth path P4, the fourth switch S4 is turned off and the sixth switch S6 is turned on to discharge the voltage of the capacitor C1 (see FIG. 5). The voltage of the capacitor C1 detected at this time is referred to as “voltage VRp”, and deterioration of the insulation resistance Rp is detected based on the voltage VRp, which will be described later.

  When the deterioration of the insulation resistance Rn on the negative electrode side is detected, as shown in FIG. 8, the first switch S1 and the sixth switch S6 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 to the first stack 12a via the first resistor R1, the first switch S1, the fifth resistor R5, the capacitor C1, the sixth switch S6, the seventh resistor R7, the insulation resistor Rn, and the second stack 12b. Thus, it is connected to the negative electrode side of the first stack 12a.

  That is, a fifth path P5 is formed to connect the first and second stacks 12a and 12b and the capacitor C1 via the insulation resistance Rn on the negative electrode side. At this time, when the resistance value of the insulation resistance Rn is normal, the fifth path P5 hardly conducts, and when the insulation resistance Rn is deteriorated and the resistance value is decreased, the fifth path P5 is It will be conducted.

  Then, after a predetermined time has elapsed since the fifth path P5 was formed, as shown in FIG. 5, the voltage of the capacitor C1 is discharged. The voltage of the capacitor C1 detected at this time is "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 insulation resistances Rp and Rn, charging is performed for a predetermined time shorter than the time required for full charge, and the charging voltage is used as voltages VRp and VRn to detect deterioration of insulation resistances Rp and Rn. I do.

  By the way, in the charge / discharge system 1 described above, for example, the boost converter 51 may operate in a state where a charge path (fifth path P5) for detecting deterioration of the insulation resistance Rn is formed. In such a case, the body voltage may fluctuate and exceed the voltage of the power supply depending on, for example, the state of the insulation resistance Rn, the operation timing of the boost converter 51, and the like.

  When the body voltage exceeds the voltage of the power supply, the capacitor C1 is charged with a negative voltage. Specifically, as shown in FIG. 8, when a current flows from the boost converter 51 as in the charging path P5a and the current in the charging path P5a becomes larger than the current in the fifth path P5, the capacitor C1 is charged with a negative voltage. It becomes. In such a case, in the prior art, the voltage of the capacitor C1 can not be accurately detected, and as a result, the deterioration detection accuracy of the insulation resistance Rn may be deteriorated.

  Further, as shown in FIG. 7, when boost converter 51 operates in a state where a charge path (fourth path P4) for detecting deterioration of insulation resistance Rp, for example, is formed, charge path P4a from boost converter 51 is performed. The current may flow like. The charging path P4a and the charging path P5a illustrated in FIGS. 7 and 8 are both examples of the flow of current.

  In the above case, the capacitor C1 is charged with the voltage from the boost converter 51 in addition to the voltages from the first and second stacks 12a and 12b, so that the voltage of the capacitor C1 is increased. It has sometimes been difficult to detect deterioration accurately.

  Therefore, in the deterioration detection device 23 according to the present embodiment, even when the boost converter 51 is provided, the deterioration detection accuracy of the insulation resistances Rp and Rn can be improved. Hereinafter, the configuration of the deterioration detection device 23 will be described in more detail.

  As shown in FIG. 2, the control unit 26 of the deterioration detection device 23 is a microcomputer including a CPU, a RAM, a ROM, and the like, and includes the voltage detection circuit unit 24 and the A / D conversion unit 25. Control the whole. Specifically, the control unit 26 includes a charge path formation unit 26a, a discharge path formation unit 26b, a voltage detection unit 26c, a charge state monitoring unit 26d, and a deterioration detection unit 26e.

  The charge path formation unit 26a controls the first to sixth switches S1 to S6 to form first, third to fifth paths P1 and P3 to P5, that is, form a charge path (FIG. 4, FIG. 6 to 8).

  The switching patterns of the first to sixth switches S1 to S6 are stored in advance in a storage unit such as a RAM and a ROM. The charge path formation unit 26a and the discharge path formation unit 26b form a charge path or a discharge path by reading out the switching pattern from the storage unit at an appropriate timing.

  The discharge path formation unit 26b controls the first to sixth switches S1 to S6 to form a second path P2, that is, form a discharge path (see FIG. 5).

  When the discharge path is formed by the discharge path formation unit 26b, the voltage detection unit 26c detects the voltage of the charged capacitor C1 through the A / D conversion unit 25. Specifically, the voltage detection unit 26c detects the first and second stack voltages and the voltages VRp and VRn described above.

  The voltage detection unit 26c is configured to be able to detect the negative voltage charged in the capacitor C1. Thus, for example, as described above, even when the capacitor C1 is charged with a negative voltage, the voltage of the capacitor C1 can be accurately detected, thereby improving the deterioration detection accuracy of the insulation resistances Rp and Rn. be able to.

  Specifically, the A / D conversion unit 25 provided between the voltage detection unit 26c and the capacitor C1 is offset so that the input voltage range includes the positive voltage and the negative voltage. That is, for example, when the input voltage range of the A / D conversion unit 25 is 0V to 200V, this is offset to be -100V to 100V. Thus, the voltage detection unit 26c can detect the negative voltage of the capacitor C1 with a simple configuration.

  Although the input voltage range of the A / D converter 25 is offset in order to detect the negative voltage of the capacitor C1 in the above description, the present invention is not limited to this. That is, for example, the input voltage range of A / D conversion unit 25 is expanded to include positive voltage and negative voltage, or used for detection of A / D conversion unit 25 used for detection of positive voltage and negative voltage. Each of the A / D conversion units 25 may be provided.

  The voltage detection unit 26c outputs a signal indicating the detected voltage of the capacitor C1 to the charge state monitoring unit 26d and the deterioration detection unit 26e.

  The charge state monitoring unit 26d determines the first and second stack voltages based on the first and second stack voltages detected after the capacitor C1 is charged in the first path P1 and the third path P3 (see FIGS. 4 and 6). Monitor the charge status of 12a and 12b. Then, the charge state monitoring unit 26d outputs information indicating the monitoring result of the charge state of the assembled battery 10 including the first and second stacks 12a and 12b to the vehicle control device 30 (see FIG. 1). In addition, the vehicle control apparatus 30 performs vehicle control according to the monitoring result of the charge condition of the assembled battery 10, as mentioned above.

  Deterioration detection unit 26e causes deterioration of insulation resistances Rp and Rn based on voltages VRp and VRn of capacitor C1 detected after charging capacitor C1 in fourth path P4 and fifth path P5 (see FIGS. 7 and 8). To detect

  Specifically, if the insulation resistances Rp and Rn deteriorate, the voltage charged to the capacitor C1 increases. Therefore, when the voltage of the charged capacitor C1 increases, the deterioration of the insulation resistances Rp and Rn is detected Make it

  Specifically, the deterioration detection unit 26e first adds the voltage VRp and the voltage VRn to calculate the voltage VRp + VRn. This makes it possible to eliminate the influence of the boost converter 51 in the detection of deterioration of the insulation resistances Rp and Rn.

That is, as shown in FIGS. 7 and 8, the voltage VRp and the voltage VRn charged to the capacitor C1 include the voltage from the boost converter 51 in addition to the voltage from the first and second stacks 12a and 12b. . Specifically, the voltage VRp and the voltage VRn are expressed by the following two equations.
Voltage VRp = (voltage from stack) + (voltage from boost converter)
Voltage VRn = (voltage from stack)-(voltage from boost converter)

  Therefore, if, for example, voltage VRp or voltage VRn is used as it is for detecting deterioration of insulation resistances Rp and Rn, depending on the magnitude of the voltage from boost converter 51, the deterioration may not be detected accurately.

  Therefore, in the present embodiment, the voltage from the boost converter 51 is canceled by adding the voltage VRp and the voltage VRn. Then, the influence of the boost converter 51 can be eliminated by using the added voltage VRp + VRn for detecting the deterioration of the insulation resistances Rp and Rn.

  Here, it is preferable that the time constants in the charging paths P4 and P4a shown in FIG. 7 and the time constants in the charging paths P5 and P5a shown in FIG. 8 be set to be the same.

  Specifically, as shown in FIG. 7, the sixth resistor R6 is provided in a fourth route P4 which is a charging route for detecting deterioration of the insulation resistance Rp on the positive electrode side, and one end side is the vehicle body GND and the other end side is It is connected to the capacitor C1. Further, as shown in FIG. 8, the seventh resistor R7 is provided in the fifth route P5 which is a charging route for detecting deterioration of the insulation resistance Rn on the negative electrode side, one end side is connected to the vehicle body GND and the other end side is connected to the capacitor C1. Be done.

  For example, if the resistance value of the sixth resistor R6 and the resistance value of the seventh resistor R7 are set to be different, the voltage from the boost converter 51 at the voltage VRp is the voltage from the boost converter 51 at the voltage VRn. It will be different from the voltage. As a result, even if voltage VRp and voltage VRn are added as described above, it may occur that the voltage from the boost converter can not be offset.

  Therefore, in the present embodiment, for example, by setting the resistance value of the sixth resistance R6 and the resistance value of the seventh resistance R7 to the same value, the time constant in the charging path P4, P4a and the time in the charging path P5, P5a I made it the same as the constant. Thus, when voltage VRp and voltage VRn are added, it is possible to reliably offset the voltage from boost converter 51. In the present specification, "same" is used as meaning having a certain width including not only identical but also substantially identical.

  The deterioration detection unit 26e compares the added voltage VRp + VRn with a threshold value Va which is a preset voltage value, and detects deterioration of the insulation resistances Rp and Rn based on the comparison result. Here, in the present embodiment, since the threshold value Va is set to a voltage value, the time required for the process of detecting the deterioration of the insulation resistances Rp and Rn can be shortened in the deterioration detection unit 26e.

  Specifically, in the prior art, the resistance values of the insulation resistors Rp and Rn are calculated based on, for example, the voltage VRp or the voltage VRn of the capacitor C1 and the stack voltage. And in the prior art, when the calculated resistance value becomes below the threshold value which is a preset resistance value, degradation of insulation resistance Rp and Rn was detected. Therefore, it takes time to calculate the resistance values of the insulation resistances Rp and Rn, and the processing time for detecting the deterioration of the insulation resistances Rp and Rn may be relatively long.

  When the insulation resistance Rp and the insulation resistance Rn are not deteriorated and the resistance value is not lowered, the capacitor C1 is hardly charged or a sufficiently small voltage is charged even if it is charged. Therefore, the deterioration detection unit 26e according to the present embodiment compares the voltage VRp + VRn with a threshold value Va preset at a relatively low voltage value.

  Then, when voltage VRp + VRn of capacitor C1 exceeds threshold value Va, deterioration detection unit 26e detects the deterioration of insulation resistances Rp and Rn, in other words, that abnormality occurs in insulation resistances Rp and Rn. judge. On the other hand, when the voltage VRp + VRn is less than the threshold value Va, the deterioration detecting unit 26e determines that the insulation resistances Rp and Rn are not deteriorated, in other words, the insulation resistances Rp and Rn are normal.

  As described above, in the present embodiment, since the threshold value Va is set to the voltage value, deterioration of the insulation resistances Rp and Rn is performed for the processing time for which the resistance values of the insulation resistances Rp and Rn have been calculated. The time required for the detection process can be shortened.

  Although the voltage VRp + VRn is used to detect deterioration of the insulation resistances Rp and Rn in the above description, the present invention is not limited to this. For example, the input voltage of the A / D converter 25 may be used.

  Further, the voltage VRp + VRn of the capacitor C1 described above fluctuates due to the increase and decrease of the stack voltage supplied to the capacitor C1. Therefore, the deterioration detection unit 26e switches the threshold value Va according to the stack voltage. Specifically, the deterioration detection unit 26e increases the threshold value Va as the stack voltage increases. Here, the stack voltage is a value obtained by adding the first stack voltage of the first stack 12 a and the second stack voltage of the second stack 12 b.

  As a result, in the deterioration detecting unit 26e, the threshold value Va can be set to an appropriate voltage value corresponding to increase or decrease of the stack voltage, thereby further improving the detection accuracy of the deterioration of the insulation resistances Rp and Rn. Can.

  Further, it is preferable that the deterioration detection unit 26e switch the threshold value Va in accordance with the stack voltage detected by the voltage detection unit 26c immediately before comparing the voltage VRp + VRn of the capacitor C1 with the threshold value Va. Thereby, it is possible to set the threshold value Va to an appropriate voltage value corresponding to the current charging state of the power supply.

  In the above, the stack voltage detected by the voltage detection unit 26 c is used immediately before the comparison, but the present invention is not limited to this. That is, for example, the deterioration detection unit 26e may calculate the average value of the stack voltages for a plurality of times detected by the voltage detection unit 26c, and switch the threshold value Va according to the average value.

  Thereby, for example, even when the stack voltage instantaneously increases or decreases, threshold value Va does not change rapidly, and thus threshold value Va is set to an appropriate voltage value corresponding to the charging state of the power supply. It becomes possible. In addition, various average values, such as a simple average and a weighted average, can be applied to the above-mentioned average value.

  The threshold value Va described above is, for example, stored in advance in the storage unit. As a result, the deterioration detection unit 26e only needs to read out the threshold value Va corresponding to the stack voltage from the storage unit, and the processing time for detecting deterioration of the insulation resistances Rp and Rn can be further shortened. Can also be reduced.

  Further, in the present embodiment, for example, a reference resistance (not shown) or the like for forcibly creating a short circuit state is connected to the fourth path P4 or the fifth path P5, and the capacitor C1 is charged in such a short circuit state. Preferably, the value of the voltage VRp + VRn is set as the threshold value Va.

  Thus, by setting the threshold value Va based on the actual measurement value, for example, even if there is an individual difference between the capacitor C1 and each of the resistors R1 to R7, the threshold value Va is absorbed as the individual difference is absorbed. Thus, the detection accuracy of the deterioration of the insulation resistances Rp and Rn can be further improved.

  The deterioration detection unit 26e 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 vehicle control according to the deterioration state, a notification operation to the user, and the like.

<3. Specific operation of charge state monitoring process and deterioration detection process>
Next, specific operations of the charge state monitoring process and the deterioration detection process performed by the battery monitoring system 20 configured as described above will be described with reference to FIG. FIG. 9 is a flowchart showing a part of the processing procedure of the processing executed by the battery monitoring system 20. Note that various processes shown in FIG. 9 are executed based on control by the control unit 26 of the deterioration detection device 23.

  As shown in FIG. 9, the control unit 26 detects a first stack voltage of the first stack 12a (step S1), and then detects a voltage VRp of the capacitor C1 (step S2). Next, the control unit 26 detects the second stack voltage of the second stack 12b (step S3), and then detects the voltage VRn of the capacitor C1 (step S4).

  Next, after calculating voltage VRp + VRn (step S5), control unit 26 calculates a stack voltage (step S6). The stack voltage is, for example, a value obtained by adding the first stack voltage and the second stack voltage detected in steps S1 and S3.

  Subsequently, the control unit 26 switches the threshold value Va according to the stack voltage (step S7). The process of switching the threshold value Va is not necessarily performed each time the stack voltage is detected, and may be performed once every time the stack voltage is detected a predetermined number of times, for example.

  Control unit 26 compares voltage VRp + VRn with switched threshold value Va (step S8). Then, when voltage VRp + VRn is equal to or higher than threshold value Va (Yes at step S8), control unit 26 detects deterioration of insulation resistances Rp and Rn (step S9). On the other hand, when voltage VRp + VRn is less than threshold value Va (step S8, No), control unit 26 determines that insulation resistances Rp and Rn are not deteriorated (step S10).

  Next, the control unit 26 transmits information indicating the deterioration state of the insulation resistances Rp and Rn as the deterioration detection result, and information indicating the first and second stack voltages and the stack voltage as the monitoring result of the charge state of the assembled battery 10 It outputs to the control apparatus 30 (step S11).

  As described above, the deterioration detection device 23 according to the first embodiment includes the capacitor C1, the voltage detection unit 26c, and the deterioration detection unit 26e. When the vehicle includes the voltage converter 50, the voltage converter 50 boosts the voltage output from the power supply and supplies the voltage to the motor 40.

  The capacitor C1 is connected to the insulated power supply to perform charging and discharging. The voltage detection unit 26c detects the voltage of the capacitor C1. The deterioration detection unit 26e detects the deterioration of the insulation resistances Rp and Rn based on the voltages VRp and VRn of the capacitor C1 detected by the voltage detection unit 26c. The voltage detection unit 26c can detect the negative voltage charged in the capacitor C1.

  Thus, even in the case where the deterioration detection device 23 includes the voltage converter 50 that boosts the voltage output from the power supply, the deterioration detection accuracy of the insulation resistances Rp and Rn can be improved.

  Further, in the deterioration detection device 23, the voltage detection unit 26c detects the voltages VRp and VRn of the capacitor C1 charged in the charge paths (fourth and fifth paths P4 and P5) for detecting the deterioration of the insulation resistances Rp and Rn. To detect. The deterioration detection unit 26e compares the voltages VRp and VRn of the capacitor C1 with the threshold value Va which is a preset voltage value, and detects deterioration of the insulation resistances Rp and Rn based on the comparison result. Thereby, the time required for the process of detecting the deterioration of the insulation resistances Rp and Rn can be shortened.

<4. Configuration of Deterioration Detection Device According to Second Embodiment>
Second Embodiment
Next, a charge / discharge system 1 including the deterioration detection device 23 according to the second embodiment will be described. In the following, the same components as those in the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

  Vehicles have stray capacities that are not intended at design time. Under the influence of the stray capacitance, for example, there is a possibility that the voltage VRp or the voltage VRn of the capacitor C1 can not be accurately detected, and the accuracy of detecting the deterioration of the insulation resistances Rp and Rn may decrease.

  Therefore, for example, a resistor, a switch, or the like used for measuring the stray capacitance is added to the circuit of the voltage detection circuit unit 24 to measure the stray capacitance, and the degradation of the insulation resistances Rp and Rn is taken into consideration. A method of detecting can be considered. However, with the above-described method, the addition of an element such as a resistor complicates the configuration of the deterioration detection device 23, and may increase costs.

  Therefore, in the second embodiment, in the deterioration detection device 23, the stray capacitance can be estimated while having a simple configuration, and the deterioration of the insulation resistances Rp and Rn can be accurately detected by considering the stray capacitance. It was composition.

  FIG. 10 is a block diagram showing a configuration example of the control unit 26 of the deterioration detection device 23 according to the second embodiment. As shown in FIG. 10, the control unit 26 includes a stray capacitance estimation unit 26f in addition to the deterioration detection unit 26e and the like.

  The floating capacity estimating unit 26 f estimates the floating capacity of the charge path based on the voltage at the detection point A (see FIG. 7). In FIG. 7 and FIG. 8, the stray capacitance is virtually indicated by a broken line and denoted by the reference symbol Cp.

  FIG. 11 is a graph for explaining the estimation process of the stray capacitance Cp performed by the stray capacitance estimation unit 26 f. In the example shown in FIG. 11, a change in voltage at the detection point A when the charging circuit (fourth path P4) for detecting the deterioration of the insulation resistance Rp on the positive electrode side is formed is shown.

  In the example shown in FIG. 11, the voltage change when there is no stray capacitance Cp is shown by the solid line e1 and the voltage when the stray capacitance Cp is increased in the order of the broken line e2, the dashed dotted line e3 and the dashed double dotted line e4. It shows a change.

  Further, in the example shown in FIG. 11, the moment when the fourth path P4 is formed when the fourth and fifth switches S4 and S5 are turned on is referred to as "time t0", which is shorter than the time when the capacitor C1 is fully charged. Let the time point be "time t2". Then, a time between time t0 and t2 and a predetermined time elapsed from time t0 is referred to as "time t1".

  Before the description of FIG. 11, the detection point A will be described with reference to FIG. 7. As described above, the sixth resistor R6 is provided in the fourth path P4 for detecting the deterioration of the insulating resistor Rp, and one end side thereof is connected to the vehicle body GND (ground point). A detection point A is provided on the other end side of the sixth resistor R6.

  When stray capacitance Cp is present, the voltage at the detection point A described above is temporarily increased rapidly to the negative voltage side since the rush current due to the stray capacitance Cp flows at the moment when the fourth and fifth switches S4 and S5 are turned on. (See time t0 in FIG. 11). After that, the voltage at the detection point A gradually changes back to rise. When the stray capacitance Cp does not exist, the voltage at the detection point A is determined by only the resistance values of the insulation resistance Rp, the resistances R4 to R6, and the like, and therefore, the voltage slightly drops to the negative voltage side.

  The voltage change when the stray capacitance Cp exists is, for example, when the stray capacitance Cp is relatively small, the charge is likely to be accumulated. Therefore, as shown by the broken line e2 in FIG. It becomes. On the other hand, for example, when the stray capacitance Cp is relatively large, the charge accumulation is slow, so that the return of the voltage at the detection point A becomes slow as shown by the two-dot chain line e4 in FIG.

  In the second embodiment, the stray capacitance Cp is estimated focusing on the relationship between the stray capacitance Cp and the change in voltage at the detection point A described above.

  Specifically, the stray capacitance estimating unit 26f determines the voltage V0 at the detection point A immediately after the charge path is formed, and the voltage V1 at the detection point A after a predetermined time t1 has elapsed since the charge path was formed. The voltage change rate Vd at the detection point A is calculated based on In FIG. 11, the voltage at the detection point A at the solid line e1 is indicated by V1e1, and the voltages at the detection point A at the lines e2, e3 and e4 are indicated by Ve2, Ve3 and Ve4, respectively.

Specifically, the voltage change rate Vd is obtained by subtracting the absolute value of the voltage V1 from the absolute value of the voltage V0 and dividing the subtracted value by the absolute value of the voltage V0, as shown by the following equation. It is.
Voltage change rate Vd = (| V0 |-| V1 |) / | V0 |

  Then, the stray capacitance estimating unit 26 f estimates the stray capacitance Cp based on the calculated voltage change rate Vd. Specifically, in the stray capacitance estimating unit 26f, the stray capacitance Cp to be estimated is set to decrease as the voltage change rate Vd increases.

  The voltage falling to the negative voltage side at time t0 is substantially the same value (voltage V0) regardless of the magnitude of the stray capacitance Cp if the stray capacitance Cp before the switches S4 and S5 are turned on is fully charged. It becomes. Therefore, the stray capacitance estimating unit 26f may estimate the stray capacitance Cp based on, for example, the voltage V1 at time t1.

  As described above, in the stray capacitance estimating unit 26f, the stray capacitance Cp can be easily estimated with a simple configuration. Moreover, since it is a simple structure, cost reduction of the degradation detection apparatus 23 can also be achieved.

  Although the predetermined time from time t0 to time t1 described above can be set to any value, for example, a time that can distinguish the voltage change (voltage change rate Vd) at the detection point A depending on the magnitude of the floating capacitance Cp. It is preferable to be set to

  Further, since the voltage detection unit 26c is configured to be able to detect a negative voltage, the voltage detection unit 26c can detect the voltage even when the voltage at the detection point A falls to the negative voltage side.

  Further, although the voltage detection unit 26 c detects the negative voltage using the A / D conversion unit 25, the present invention is not limited to this. That is, for example, as shown by an imaginary line in FIG. 3, an A / D conversion unit 25a used to estimate the stray capacitance Cp may be newly provided.

  In addition, although the stray capacitance estimating unit 26 f estimates the stray capacitance Cp based on the voltage at the detection point A, the present invention is not limited to this. That is, for example, the stray capacitance Cp may be estimated based on the voltage at the detection point B shown in FIG.

  The detection point B will be described. First, the seventh resistance R7 is provided on the fifth path P5 for detecting deterioration of the insulation resistance Rn on the negative electrode side, and one end side is connected to the vehicle body GND (grounding point). A detection point B is provided on the other end side of the seventh resistor R7.

  Although illustration is omitted, when stray capacitance Cp is present, the voltage at detection point B is positive because the rush current due to stray capacitance Cp flows at the moment the first and sixth switches S1 and S6 are turned on. The voltage changes so that it rises rapidly to the side and then gradually falls back. Therefore, the stray capacitance estimating unit 26 f can also estimate the stray capacitance Cp based on the voltage at the detection point B. The sixth resistor R6 and the seventh resistor R7 are examples of a voltage detection resistor.

  The deterioration detection unit 26e corrects the voltages VRp and VRn of the capacitor C1 based on the stray capacitance Cp estimated by the stray capacitance estimation unit 26f. FIG. 12 is a graph for explaining the correction processing performed by the deterioration detection unit 26e.

  The example shown in FIG. 12 shows a change in the charging voltage of the capacitor C1 when the charging circuit (fourth path P4) for detecting the deterioration of the insulation resistance Rp on the positive electrode side is formed. In the example shown in FIG. 12, the change in the charging voltage in the absence of the stray capacitance Cp is indicated by a solid line, while the change in the charging voltage in the presence of the stray capacitance Cp is indicated by an alternate long and short dash line.

  When stray capacitance Cp exists, the rush current by the stray capacitance Cp flows into the capacitor C1 at the moment (time t0) at which the fourth and fifth switches S4 and S5 are turned on and the fourth path P4 is formed. The charging voltage increases rapidly as compared to the case where the capacitance Cp is not present. The increase Vf of the charging voltage increases as the stray capacitance Cp increases, in other words, as the inrush current increases.

  Therefore, the deterioration detection unit 26e calculates an increase Vf of the charging voltage of the capacitor C1 generated by the stray capacitance Cp based on the estimated stray capacitance Cp. Then, the deterioration detection unit 26e corrects the voltage VRp of the capacitor C1 detected by the voltage detection unit 26c by the increase amount Vf in the second path (discharge path) P2 after the formation of the fourth path P4. . That is, a value obtained by subtracting the increase Vf from the voltage VRp of the detected capacitor C1 is replaced as a new voltage VRp.

  In addition, the deterioration detection unit 26e may correct the voltage VRn of the capacitor C1 detected by the voltage detection unit 26c in the second path P2 after the formation of the fifth path P5 with the increase Vf. .

  Then, the deterioration detecting unit 26e can improve the accuracy of detecting deterioration of the insulation resistances Rp and Rn by detecting deterioration of the insulation resistances Rp and Rn based on the corrected voltages VRp and VRn of the capacitor C1. .

<5. Specific Operations of Charge State Monitoring Process and Deterioration Detection Process in Second Embodiment>
Next, specific operations of the charge state monitoring process and the deterioration detection process performed by the battery monitoring system 20 according to the second embodiment will be described with reference to FIG. FIG. 13 is a flowchart showing a part of the processing procedure of processing executed by the battery monitoring system 20 according to the second embodiment. In FIG. 13, the same steps as in the first embodiment are assigned the same step numbers.

  As shown in FIG. 13, after detecting the first stack voltage in step S1, the control unit 26 forms a fourth path P4 and detects the voltages V0 and V1 at the detection point A (step S1a). Then, control unit 26 calculates voltage change rate Vd (step S1 b), and estimates stray capacitance Cp based on the calculated voltage change rate Vd (step S1 c).

  Subsequently, the control unit 26 corrects the voltages VRp and VRn based on the stray capacitance Cp after detecting the voltage VRp of the capacitor C1, the second stack voltage, and the voltage VRn of the capacitor C1 in steps S2 to S4. Step S4a).

  As a result, the control unit 26 uses the corrected voltages VRp and VRn in the processes after step S6, and as a result, deterioration detection of the insulation resistances Rp and Rn can be performed with high accuracy.

  In addition, since the control unit 26 performs the process of estimating the stray capacitance Cp in a series of processes of detecting the voltages VRp and VRn and detecting the deterioration of the insulation resistances Rp and Rn, the processing efficiency is good and real time It can be a process excellent in sex.

  As described above, the deterioration detection device 23 according to the second embodiment includes the capacitor C1, the voltage detection resistances (sixth and seventh resistances R6 and R7), the voltage detection portion 26c, and the stray capacitance estimation portion 26f and a deterioration detection unit 26e. The capacitor C1 is connected to the insulated power supply to perform charging and discharging. The voltage detection resistance is provided in the charge path (fourth and fifth paths P4, P5) for detecting deterioration of the insulation resistances Rp, Rn, and one end side is connected to the ground point. The voltage detection unit 26c forms the charge paths for detecting the deterioration of the insulation resistances Rp and Rn, and then forms the voltages VRp and VRn of the capacitor C1 and the detection points A and B at the other end of the voltage detection resistance. Detect the voltage. The stray capacitance estimating unit 26 f estimates the stray capacitance Cp of the charge path based on the voltages at the detection points A and B. The deterioration detection unit detects the deterioration of the insulation resistances Rp and Rn based on the voltages VRp and VRn of the capacitor C1 and the stray capacitance Cp.

  As a result, the stray capacitance Cp can be estimated with a simple configuration, and by using the estimated stray capacitance Cp, the accuracy of detecting the deterioration of the insulation resistances Rp and Rn can be improved.

  Although the voltage VRp + VRn is calculated and compared with the threshold value Va in the detection of deterioration of the insulation resistances Rp and Rn in the second embodiment described above, 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 comparing the voltage VRp of the capacitor C1 and the voltage VRn with the respective threshold values. In such a case, the threshold values respectively compared with voltage VRp and voltage VRn may be set to the same value or different values.

  In the first and second embodiments, the first stack voltage, the voltage VRp, the second stack voltage, and the voltage VRn are detected in this order, but this is an example and is not limited. The order of detection can be set arbitrarily.

  Moreover, the timing which performs a degradation detection process in 1st, 2nd embodiment is not limited above. That is, for example, the timing at which the deterioration detection process is performed may be changed, for example, at the time of starting the vehicle or at the time of stopping the vehicle, at predetermined time intervals or at predetermined traveling distances.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the invention are not limited to the specific details and representative embodiments represented 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 their equivalents.

DESCRIPTION OF SYMBOLS 1 charge / discharge system 10 assembled battery 12a 1st stack 12b 2nd stack 20 battery monitoring system 23 deterioration detection apparatus 24 voltage detection circuit unit 25 A / D conversion unit 26 control unit 26a charge route formation unit 26b discharge route formation unit 26c voltage detection Unit 26d Charge condition monitoring unit 26e Deterioration detection unit 26f Floating capacity estimation unit 30 Vehicle control device 40 Motor 50 Voltage converter 51 Boost converter 60 Failsafe relay

Claims (3)

A capacitor connected to an isolated power supply for charging and discharging;
A voltage detection resistor provided in a charge path for detecting deterioration of the insulation resistance of the power supply, one end of which is connected to the ground point;
A voltage detection unit for detecting a voltage of the capacitor and a voltage at a detection point on the other end side of the voltage detection resistor after the charge path for detecting the deterioration of the insulation resistance of the power supply is formed;
A floating capacity estimation unit configured to estimate floating capacity of the charge path based on the voltage of the detection point;
And a degradation detection unit that detects degradation of the insulation resistance of the power supply based on the voltage of the capacitor and the stray capacitance .
The stray capacity estimation unit
The voltage change rate at the detection point is calculated based on the voltage at the detection point immediately after the charge path is formed and the voltage at the detection point after a predetermined time has elapsed since the charge path was formed. And the stray capacitance is estimated based on the voltage change rate . The deterioration detection unit is
Based on the estimated stray capacitance, an increase in the charging voltage of the capacitor generated by the stray capacitance is calculated, and the voltage of the capacitor detected by the voltage detection unit is corrected with the increase, and the power supply The deterioration detection device according to claim 1, wherein the deterioration of the insulation resistance of the sensor is detected. After the charging path for detecting the deterioration of the insulation resistance of the power supply is formed, the voltage for the capacitor and the charging path for detecting the deterioration of the insulation resistance of the power supply are provided, and one end is connected to the ground point A voltage detection step of detecting a voltage at a detection point on the other end side of the resistor;
A floating capacity estimation step of estimating floating capacity of the charge path based on the voltage at the detection point;
Voltage of the capacitor, and, seen including a deterioration detecting step for detecting deterioration of the insulation resistance of the power supply on the basis of the stray capacitance,
The stray capacity estimation step
The voltage change rate at the detection point is calculated based on the voltage at the detection point immediately after the charge path is formed and the voltage at the detection point after a predetermined time has elapsed since the charge path was formed. And estimating the floating capacity based on the voltage change rate .

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