JP2014095628A - Insulation resistance reduction detection apparatus, vehicle including the same, and insulation resistance reduction detection method - Google Patents

Abstract

In detection of a decrease in insulation resistance of an electric system, erroneous detection due to individual differences is suppressed without separately providing a circuit for setting a threshold value.
An insulation resistance decrease detection device detects a decrease in insulation resistance of an electric system mounted on a vehicle. The determination unit 53 determines that the insulation resistance is reduced when the first peak value detected by the detection unit 43 falls below the threshold value when the connection state is the first connection state. The self-diagnosis unit 51 diagnoses the insulation resistance decrease detection device based on the second peak value detected by the detection unit 43 when the connection state is the second connection state. The setting unit 52 sets the threshold value such that the threshold value increases as the second peak value increases.
[Selection] Figure 1

Description

  The present invention relates to an insulation resistance decrease detection device, a vehicle including the same, and an insulation resistance decrease detection method, and more particularly, to an insulation resistance decrease detection device for detecting a decrease in insulation resistance of an electric system mounted on a vehicle and the same. The present invention relates to a vehicle and a method for detecting decrease in insulation resistance.

  Japanese Patent Laying-Open No. 2006-170714 (Patent Document 1) discloses a ground fault detection device that detects a ground fault of a high-voltage power supply. The ground fault detection device measures a pulse generation circuit, a coupling capacitor connected to a high voltage power supply, a resistance connected between the coupling capacitor and the pulse generation circuit, and a voltage between the coupling capacitor and the resistance. Voltage measuring means and ground fault detecting means for detecting a ground fault of the high voltage power supply are provided.

  In this ground fault detection device, the ground fault detection means determines that a ground fault has occurred in the high voltage power supply when the voltage detected by the voltage measurement means is lower than the threshold value (see Patent Document 1). ).

JP 2006-170714 A JP 2008-273369 A JP 2007-209158 A JP 2006-208222 A

  Since the ground fault detection apparatus as described above has individual differences, the pulse output from the pulse generation circuit and the voltage measured by the voltage measuring unit may vary due to the influence of the individual difference. Thereby, the ground fault detection device may erroneously detect the ground fault of the high voltage power supply.

  On the other hand, erroneous detection can be prevented by setting a threshold for detecting a ground fault of the high-voltage power supply for each ground fault detection device. However, for this purpose, it is necessary to separately provide a circuit for setting a threshold value in the ground fault detection device.

  Therefore, an object of the present invention is to provide an insulation resistance lowering detection device that suppresses erroneous detection due to individual differences without separately providing a circuit for setting a threshold value in the detection of a decrease in insulation resistance of an electrical system, and It is to provide a vehicle equipped with.

  Another object of the present invention is to provide a method for detecting a decrease in insulation resistance that suppresses erroneous detection due to individual differences without separately providing a circuit for setting a threshold when detecting a decrease in insulation resistance of an electrical system. It is to be.

  According to the present invention, the insulation resistance decrease detecting device detects a decrease in insulation resistance of an electric system mounted on a vehicle. The insulation resistance lowering detection apparatus includes a signal line, a detection unit, a resistance, a switching unit, and a control device. The signal line is supplied with an AC signal for determining a decrease in insulation resistance. The detection unit detects the peak value of the AC signal in the signal line. The resistor has a predetermined resistance value. The switching unit is configured such that the first connection state in which the signal line is electrically connected to the electrical system, the electrical connection between the signal line and the electrical system is interrupted, and the signal line is electrically connected to the resistor. The connection state of the signal line is switched between the second connection state and the second connection state. The control device determines a decrease in insulation resistance. The control device includes a determination unit, a self-diagnosis unit, and a setting unit. The determination unit determines that the insulation resistance has decreased when the first peak value indicating the peak value detected by the detection unit when the connection state is the first connection state falls below a threshold value. To do. The self-diagnosis unit diagnoses the insulation resistance drop detection device based on the second peak value indicating the peak value detected by the detection unit when the connection state is the second connection state. The setting unit sets the threshold value such that the threshold value increases as the second peak value increases.

  Preferably, the control device further includes a storage unit. In the storage unit, a threshold value is stored in advance corresponding to the magnitude of the second peak value. The setting unit selects the threshold value stored by the storage unit according to the magnitude of the second peak value.

  Preferably, the self-diagnosis unit diagnoses the insulation resistance decrease detection device when the vehicle is activated. The setting unit sets a threshold when diagnosis by the self-diagnosis unit is executed.

  Preferably, the electrical system has a characteristic that the rate of change of the crest value with respect to the resistance value of the insulation resistance increases as the resistance value of the insulation resistance decreases. The threshold value is set corresponding to the resistance value of the insulation resistance. The predetermined resistance value is smaller than the resistance value of the insulation resistance corresponding to the threshold value.

  Preferably, the insulation resistance decrease detecting device further includes a signal generating unit. The signal generator applies an AC signal to the signal line. The switching unit includes a first switch and a second switch. The first switch is provided between the signal line and the electrical system. The second switch is provided between the signal line and a resistor having a predetermined resistance value.

  According to the present invention, the vehicle includes any one of the above-described insulation resistance decrease detection devices.

  According to the present invention, the insulation resistance decrease detection method detects a decrease in insulation resistance of an electrical system mounted on a vehicle. The vehicle includes a signal line, a detection unit, a resistor, and a switching unit. The signal line is supplied with an AC signal for determining a decrease in insulation resistance. The detection unit detects the peak value of the AC signal in the signal line. The resistor has a predetermined resistance value. The switching unit is configured such that the first connection state in which the signal line is electrically connected to the electrical system, the electrical connection between the signal line and the electrical system is interrupted, and the signal line is electrically connected to the resistor. The connection state of the signal line is switched between the second connection state and the second connection state. Insulation resistance decrease detection method is such that when the first peak value indicating the peak value detected by the detector when the connection state is the first connection state falls below a threshold value, the insulation resistance decreases. A step of determining that the vehicle is present, a step of diagnosing the vehicle based on a second peak value indicating a peak value detected by the detection unit when the connection state is the second connection state, and a second peak value And setting the threshold value such that the higher the threshold value, the higher the threshold value.

  In the present invention, it is determined that the insulation resistance is lowered when the peak value falls below the threshold value. The threshold value is set so that the threshold value increases as the peak value used for diagnosis by the self-diagnosis unit increases. Thereby, the threshold value according to the individual difference can be set by using the self-diagnosis circuit. Therefore, according to the present invention, in the detection of a decrease in the insulation resistance of the electric system, it is possible to suppress erroneous detection due to individual differences without separately providing a circuit for setting a threshold value.

It is a figure showing composition of vehicles provided with an insulation resistance fall detection device by an embodiment of this invention. It is a figure which shows the relationship between the crest value which the detector shown in FIG. 1 outputs, and the insulation resistance value of an electric system. It is a graph which shows the relationship between the crest value at the time of self-diagnosis, and a threshold value. It is a functional block diagram regarding the insulation resistance fall detection of the control apparatus shown in FIG. It is a flowchart explaining the process regarding the insulation resistance fall detection performed with the control apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram showing a configuration of a vehicle including an insulation resistance decrease detecting device according to an embodiment of the present invention. Referring to FIG. 1, vehicle 100 includes a power storage device B, an electric system 70, a detector 40, a control device 50, and a warning lamp 60.

  Vehicle 100 is an electric vehicle that travels using electric power stored in power storage device B. The vehicle 100 is, for example, a hybrid vehicle or an electric vehicle.

  The power storage device B is a chargeable / dischargeable DC power supply, and is configured by, for example, a secondary battery such as a nickel metal hydride battery or a lithium ion battery, or a capacitor. The power storage device B supplies electric power to the electric system 70 and is charged by electric power from the electric system 70 during power regeneration.

  Electrical system 70 includes an inverter (not shown). The inverter converts the electric power from power storage device B into electric power for driving a motor (not shown). The electric system 70 is controlled by a signal from the control device 50. The electric system 70 is electrically insulated from the ground node GND (vehicle chassis).

  Detector 40 is provided to detect a decrease in insulation resistance between electrical system 70 and ground node GND. The detector 40 is connected to the electrical system 70. The detector 40 outputs an AC signal having a low frequency (for example, 2.5 Hz) to the electric system 70, and outputs a peak value Vk of the AC signal to the control device 50. The peak value Vk decreases as the insulation resistance decreases.

  Detector 40 includes a signal generation unit 41, resistors R <b> 1 and R <b> 2, a capacitor C, a switching unit 42, and a detection unit 43. The switching unit 42 includes switches SW1 and SW2. The detection unit 43 includes a band pass filter 43a and a peak hold circuit 43b.

  Signal generator 41 and resistor R1 are connected in series between node N1 and ground node GND. Capacitor C and switch SW1 are connected in series between node N1 and electrical system 70. Resistor R2 and switch SW2 are connected in series between signal line SL connected to node N1 and ground node GND.

  The switching unit 42 is configured such that the first connection state in which the signal line SL is electrically connected to the electric system 70, the electric connection between the signal line SL and the electric system 70 is interrupted, and the signal line SL is connected to the resistor R2. The connection state of the signal line SL can be switched between the second connection state electrically connected. Specifically, when the connection state is the first connection state, the switch SW1 is closed and the switch SW2 is opened. When the connection state is the second connection state, the switch SW1 is opened and the switch SW2 is closed. The connection state of the switching unit 42 is controlled by a signal CMD received from the control device 50.

  The signal generator 41 outputs the low-frequency AC signal. The band pass filter 43a receives an AC signal transmitted through the signal line SL connected to the node N1, extracts only a component of a predetermined frequency (for example, 2.5 Hz) from the received AC signal, and performs peak hold. Output to the circuit 43b. Peak hold circuit 43b holds the peak of the AC signal received from bandpass filter 43a, and outputs the held peak value Vk to control device 50.

  Control device 50 receives activation instruction IG. The activation instruction IG is switched from the off state to the on state when the driver turns on a start switch such as an ignition switch when the vehicle 100 is activated. The start instruction IG is switched from the on state to the off state when the driver turns off the ignition switch when the operation of the vehicle 100 is stopped.

  When vehicle 100 is activated, control device 50 determines the presence or absence of a decrease in insulation resistance based on the magnitude of peak value Vk when the connection state is the first connection state. The electrical system 70 is electrically insulated from the ground node GND as described above. However, if the insulation resistance between electrical system 70 and ground node GND decreases due to some factor, the voltage at node N1 decreases. Therefore, the control device 50 determines that the insulation resistance is reduced when the peak value Vk falls below the threshold value.

  When it is determined that the insulation resistance is reduced, the control device 50 generates a signal EMG and outputs the signal EMG to the warning lamp 60. The warning lamp 60 lights up in response to the signal EMG. Thereby, the driver | operator can know that the fall of insulation resistance has arisen.

  Furthermore, the control device 50 detects an abnormality of the detector 40 based on the magnitude of the peak value Vk when the connection state is the second connection state (hereinafter also referred to as self-diagnosis). The control device 50 determines that the detector 40 is normal when the peak value Vk is within a predetermined range. On the other hand, when a disconnection or a short circuit occurs in the circuit of the detector 40, the peak value Vk is not within the predetermined range. Therefore, the control device 50 determines that the detector 40 is abnormal when the peak value Vk is not within the predetermined range.

  Here, the detector 40 has individual differences. For example, the voltage output from the signal generation unit 41 of the detector 40 varies depending on the individual difference of the parts constituting the signal generation unit 41. In addition, the peak value Vk output from the detection unit 43 of the detector 40 varies depending on the individual difference of the parts constituting the detection unit 43. Thereby, there is a possibility that the presence or absence of a decrease in insulation resistance is erroneously determined.

  Therefore, in the present embodiment, a threshold value is set based on the peak value Vk output at the time of self-diagnosis. As a result, it is possible to prevent erroneous determination of the presence or absence of a decrease in insulation resistance due to individual differences in the detector 40. Since the threshold value is set by using the peak value Vk output at the time of self-diagnosis, it is not necessary to provide a separate resistor for setting the threshold value.

  FIG. 2 is a diagram showing the relationship between the peak value Vk output from the detector 40 shown in FIG. 1 and the insulation resistance value of the electrical system. Referring to FIG. 2, solid lines LN <b> 1 to LN <b> 3 indicate the characteristics of detectors 40 having different peak values detected due to individual differences. For example, even if the insulation resistance values are the same, the detector 40 that outputs the peak value represented by the solid line LN3 outputs a larger value than the detector 40 that outputs the peak value represented by the solid line LN2. On the other hand, the detector 40 that outputs the peak value represented by the solid line LN1 outputs a smaller value than the detector 40 that outputs the peak value represented by the solid line LN2.

  The resistance value Y1 indicates a resistance value at the time of self-diagnosis (resistance value of the resistor R2). The resistance value Y2 indicates a resistance value when it is determined that the insulation resistance of the electrical system 70 is abnormal. The resistance value Y3 indicates a resistance value when it is determined that the insulation resistance of the electric system 70 is normal.

  In solid lines LN1 to LN3, the peak value Vk decreases as the insulation resistance value decreases. Therefore, a decrease in insulation resistance can be detected by detecting the peak value Vk. However, the peak value Vk may fluctuate due to individual differences of the detector 40 as described above.

  Therefore, in the present embodiment, a threshold value is set based on the peak value Vk detected at the time of self-diagnosis. Specifically, in the solid line LN1, when the insulation resistance value is Y1, the detector 40 outputs a peak value X1. When the insulation resistance value is Y2, the detector 40 outputs a peak value A1, and when the insulation resistance value is Y3, the detector 40 outputs a peak value B1.

  Therefore, when the peak value Vk detected at the time of self-diagnosis is X1, control device 50 sets A1 as a threshold value (hereinafter also referred to as an abnormality determination value) for determining that the insulation resistance is abnormal. The threshold value for determining that the insulation resistance is normal (hereinafter also referred to as a normal determination value) is set to B1.

  Similarly, in the solid line LN2, when the insulation resistance value is Y1, the detector 40 outputs a peak value X2. When the insulation resistance value is Y2, the detector 40 outputs a peak value A2, and when the insulation resistance value is Y3, the detector 40 outputs a peak value B2. Therefore, when the peak value Vk detected at the time of self-diagnosis is X2, control device 50 sets the abnormality determination value to A2 and sets the normality determination value to B2.

  Similarly, in the solid line LN3, when the insulation resistance value is Y1, the detector 40 outputs a peak value X3. When the insulation resistance value is Y2, the detector 40 outputs a peak value A3, and when the insulation resistance value is Y3, the detector 40 outputs a peak value B3. Therefore, when the peak value Vk detected at the time of self-diagnosis is X3, control device 50 sets the abnormality determination value to A3 and sets the normality determination value to B3.

  FIG. 3 is a chart showing the relationship between the crest value and the threshold during self-diagnosis. Referring to FIG. 3, control device 50 has a storage unit that stores a table representing the relationship between peak values X1 to Xn, abnormality determination values A1 to An, and normal determination values B1 to Bn at the time of self-diagnosis. The control device 50 acquires the abnormality determination value and the normal determination value by referring to the table based on the peak value Vk obtained at the time of self-diagnosis. And the control apparatus 50 determines the presence or absence of a fall of insulation resistance with the acquired abnormality determination value and normality determination value.

  FIG. 4 is a functional block diagram related to detection of a decrease in insulation resistance of the control device 50 shown in FIG. Referring to FIG. 4, control device 50 includes a self-diagnosis unit 51, a setting unit 52, and a determination unit 53.

  When the vehicle 100 is activated, the self-diagnosis unit 51 outputs a signal CMD for controlling the switching unit 42 to the switching unit 42 so that the connection state becomes the second connection state. When the connection state is switched to the second connection state, the self-diagnosis unit 51 receives the peak value Vk from the detector 40. The self-diagnosis unit 51 determines that the detector 40 is normal when the peak value Vk is within a predetermined range. On the other hand, the self-diagnosis unit 51 determines that the detector 40 is abnormal when the peak value Vk is not within the predetermined range. Note that the predetermined range is a range for determining that no disconnection or short-circuit has occurred in the circuit of the detector 40.

  When the self-diagnosis is completed, the setting unit 52 receives the peak value Vk used during the self-diagnosis from the self-diagnosis unit 51. The setting unit 52 sets the threshold value by selecting the threshold value stored in the storage unit based on the peak value Vk. The setting unit 52 outputs the threshold value to the determination unit 53.

  The determination unit 53 outputs a signal CMD that controls the switching unit 42 to the switching unit 42 so that the connection state becomes the first connection state. When the connection state is switched to the first connection state, the determination unit 53 receives the peak value Vk from the detector 40. The determination unit 53 determines the presence or absence of a decrease in insulation resistance based on the peak value Vk. The determination unit 53 determines that the insulation resistance has decreased when the peak value Vk falls below the abnormality determination value. On the other hand, the determination unit 53 determines that the insulation resistance has not decreased when the peak value Vk exceeds the normal determination value.

  FIG. 5 is a flowchart for explaining processing related to detection of a decrease in insulation resistance executed by the control device 50 shown in FIG. Note that each step in the flowchart shown in FIG. 5 is executed in response to a predetermined period or a predetermined condition being established when a program stored in advance in control device 50 is called from the main routine. It is realized by. Alternatively, for some steps, it is also possible to construct dedicated hardware (electronic circuit) and realize processing.

  Referring to FIG. 5, in step (hereinafter, step is abbreviated as S) 10, control device 50 determines whether or not detector 40 is powered on. Specifically, when electric power is supplied to the detector 40 when the vehicle 100 is activated, the control device 50 determines that the power source of the detector 40 is turned on. When it is not determined that the power of detector 40 is turned on (NO in S10), control device 50 does not perform the subsequent processing.

  When it is determined that the power of detector 40 is turned on (YES in S10), control device 50 determines whether or not the self-diagnosis is completed (S20). If it is not determined that self-diagnosis has been completed (NO in S20), control device 50 executes self-diagnosis (S30).

  Specifically, the control device 50 outputs a signal CMD for controlling the switching unit 42 to the switching unit 42 so that the connection state becomes the second connection state. When the connection state is switched to the second connection state, control device 50 receives peak value Vk from detector 40. The control device 50 determines that the detector 40 is normal when the peak value Vk is within a predetermined range. On the other hand, the control device 50 determines that the detector 40 is abnormal when the peak value Vk is not within the predetermined range.

  When it is determined that the self-diagnosis is completed (YES in S20), control device 50 determines whether or not the setting of the threshold value for determining the decrease in insulation resistance of electric system 70 is completed. (S40). If it is not determined that the threshold setting has been completed (NO in S40), control device 50 sets the threshold (S50). Specifically, the control device 50 sets the threshold value by referring to the table shown in FIG. 3 based on the peak value Vk used during the self-diagnosis.

  When it is determined that the setting of the threshold value has been completed (YES in S40), control device 50 executes a process for determining a decrease in insulation resistance (S60). Specifically, the control device 50 outputs a signal CMD for controlling the switching unit 42 to the switching unit 42 so that the connection state becomes the first connection state. When the connection state is switched to the first connection state, control device 50 receives peak value Vk from detector 40. The control device 50 determines that the insulation resistance has decreased when the peak value Vk falls below the abnormality determination value. On the other hand, the control device 50 determines that the insulation resistance is not lowered when the peak value Vk exceeds the normal determination value.

  As described above, in this embodiment, it is determined that the insulation resistance is lowered when the peak value is below the threshold value. The threshold value is set so that the threshold value increases as the peak value used for diagnosis by the self-diagnosis unit 51 increases. Thereby, the threshold value according to the individual difference can be set by using the self-diagnosis circuit. Therefore, according to this embodiment, in the detection of the decrease in the insulation resistance of the electric system 70, it is possible to suppress erroneous detection due to individual differences without separately providing a circuit for setting a threshold value.

  In this embodiment, self-diagnosis is executed when vehicle 100 is activated. A threshold is set when self-diagnosis is performed. For this reason, the influence when the detector 40 changes with time can be suppressed.

  Further, in this embodiment, the electric system 70 has a characteristic that the rate of change of the crest value with respect to the resistance value of the insulation resistance increases as the resistance value of the insulation resistance decreases. The threshold value is set corresponding to the resistance value of the insulation resistance. The predetermined resistance value is smaller than the resistance value of the insulation resistance corresponding to the threshold value. Therefore, since the peak value for self-diagnosis can be detected in a region where the rate of change of the peak value with respect to the resistance value is high, the threshold value can be set with high accuracy.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  40 detectors, 41 signal generation units, 42 switching units, 43 detection units, 43a band pass filters, 43b peak hold circuits, 50 control devices, 60 warning lamps, 70 electrical systems, 100 vehicles, B power storage devices, C capacitors, GND Ground node, R1, R2 resistance, SL signal line, SW1, SW2 switch.

Claims (7)

An insulation resistance decrease detection device for detecting a decrease in insulation resistance of an electrical system mounted on a vehicle,
A signal line to which an AC signal for determining a decrease in the insulation resistance is provided;
A detection unit for detecting a peak value of the AC signal in the signal line;
A resistor having a predetermined resistance value;
The first connection state in which the signal line is electrically connected to the electrical system, the electrical connection between the signal line and the electrical system is interrupted, and the signal line is electrically connected to the resistor. A switching unit that switches a connection state of the signal line with a second connection state.
A controller for determining a decrease in the insulation resistance,
The control device includes:
When the first peak value indicating the peak value detected by the detector when the connection state is the first connection state falls below a threshold value, it is determined that the insulation resistance has decreased. A determination unit to perform,
A self-diagnosis unit for diagnosing the insulation resistance decrease detection device based on a second peak value indicating a peak value detected by the detection unit when the connection state is the second connection state;
And a setting unit configured to set the threshold value such that the threshold value increases as the second peak value increases. The control device further includes a storage unit in which the threshold is stored in advance corresponding to the magnitude of the second peak value,
The insulation resistance reduction detecting device according to claim 1, wherein the setting unit selects the threshold value stored by the storage unit according to the magnitude of the second peak value. The self-diagnosis unit diagnoses the insulation resistance decrease detection device when the vehicle is activated,
The insulation resistance lowering detection apparatus according to claim 1, wherein the setting unit sets the threshold value when diagnosis by the self-diagnosis unit is executed. The electrical system has a characteristic that the rate of change of the crest value with respect to the resistance value of the insulation resistance increases as the resistance value of the insulation resistance decreases.
The threshold value is set corresponding to the resistance value of the insulation resistance,
The insulation resistance lowering detection apparatus according to claim 1, wherein the predetermined resistance value is smaller than a resistance value of the insulation resistance corresponding to the threshold value. A signal generation unit for supplying the AC signal to the signal line;
The switching unit is
A first switch provided between the signal line and the electrical system;
The insulation resistance lowering detection apparatus according to claim 1, further comprising: a second switch provided between the signal line and the resistor having a predetermined resistance value.   A vehicle comprising the insulation resistance reduction detecting device according to claim 1. An insulation resistance decrease detection method for detecting a decrease in insulation resistance of an electrical system mounted on a vehicle,
The vehicle is
A signal line to which an AC signal for determining a decrease in the insulation resistance is provided;
A detection unit for detecting a peak value of the AC signal in the signal line;
A resistor having a predetermined resistance value;
The first connection state in which the signal line is electrically connected to the electrical system, the electrical connection between the signal line and the electrical system is interrupted, and the signal line is electrically connected to the resistor. A switching unit that switches a connection state of the signal line with a second connection state.
The insulation resistance drop detection method is:
When the first peak value indicating the peak value detected by the detector when the connection state is the first connection state falls below a threshold value, it is determined that the insulation resistance has decreased. And steps to
Diagnosing the vehicle based on a second peak value indicating a peak value detected by the detection unit when the connection state is the second connection state;
Setting the threshold value such that the threshold value increases as the second peak value increases.

Images