JP2011055631A - Relay failure diagnostic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relay failure diagnostic device capable of reliably diagnosing a main relay for welding failure. <P>SOLUTION: The relay failure diagnostic device includes a relay control unit 10 that outputs on/off signals to the respective main relays 5, 7 on the (-) side and on the (+) side and controls connection/disconnection of each relay, a converter drive control unit 12 that outputs a drive command signal for driving a DC/DC converter 9 connected in parallel with an inverter 2 between a negative power line 4 and a positive power line 6, and a relay failure diagnosis unit 11. The diagnosis unit individually switches an on signal or an off signal and outputs them to the individual main relays 5, 7 through the relay control unit 10. It determines whether or not each main relay 5, 7 is welded based on variation in the output current and/or output voltage from the DC/DC converter 9 when a drive command signal is outputted from the converter drive control unit 12 to the DC/DC converter 9. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a relay failure diagnosis device that diagnoses whether or not welding (failure) has occurred in a relay connected between a DC power source such as a high-voltage battery and a load.

  An electric vehicle having a driving motor such as an electric vehicle or a hybrid vehicle includes an inverter that drives the motor and a high-voltage battery that supplies DC power to the inverter. A relay for connecting / disconnecting the power supply line is disposed between the battery and the inverter connected via the power supply line (connection wiring).

  Further, when an overcurrent flows in the power supply line, the relay may be welded and a relay failure may occur. For this reason, conventionally, a relay failure diagnosis device that diagnoses whether or not a relay is welded has been proposed (see, for example, Patent Document 1).

JP-A-2005-116485

  In the device of Patent Document 1 (relay welding detection device), based on the voltage output from the inverter, it is determined whether the positive or negative relay of the battery is welded. For this reason, when an abnormality or the like occurs in the inverter, it is impossible to detect a predetermined voltage output from the inverter, and thus there is a problem that it is not possible to determine whether the relay is welded. .

  Accordingly, an object of the present invention is to provide a relay failure diagnosis device that can reliably diagnose the presence or absence of a relay welding failure even when an abnormality or the like occurs in an inverter.

  In order to achieve the above object, the present invention provides a first relay for connecting / disconnecting a first power line connecting a positive electrode side of a DC power source and a first load, a negative electrode side of the DC power source, and a first power source. In order to diagnose whether or not each relay of the second relay that connects / cuts off the second power line that connects to the load of each of the first and second relays is welded, the first and second relays are turned on / off. A relay control means for outputting a signal to control connection / disconnection of each of the first and second relays, and in parallel with the first load between the first power line and the second power line; It has a drive means for connecting a second load and outputting a drive command signal for driving the second load. Then, the relay failure diagnosis means outputs an on signal or an off signal to the first and second relays separately from the relay control means, and outputs a drive command signal from the drive means to the second load. Based on the change in the output current or / and the output voltage from the second load at this time, it is diagnosed whether each of the first and second relays is welded.

  According to the present invention, if welding occurs in the first relay and / or the second relay, the welded relay is in a connected state even if an OFF signal is output from the relay control means. Therefore, the ON / OFF signal is individually switched and output from the relay control means to the first and second relays, respectively, and the drive command signal is output from the drive means to the first load or the second load. Thus, if welding has occurred in the first relay or / and the second relay, the output current or / and output voltage from the second load will change, so the output current or / and output voltage at this time Based on the change, it is possible to diagnose whether or not the first and second relays are welded.

The figure which shows schematic structure at the time of applying the relay failure diagnostic apparatus which concerns on Embodiment 1 of this invention to the drive system of an electric vehicle. The block diagram which shows the structure of the relay failure diagnostic part of the relay failure diagnostic apparatus which concerns on Embodiment 1 of this invention. The figure which shows the ON / OFF timing of each signal at the time of the failure diagnosis process of each main relay of Embodiment 1-4, and the change of a battery charging current and a power supply voltage. 6 is a flowchart illustrating a failure diagnosis process for a (−) side main relay according to the first embodiment. 6 is a flowchart illustrating a fault diagnosis process for the (+) side main relay according to the first embodiment. 9 is a flowchart showing a failure diagnosis process for a (−) side main relay in the second embodiment. 9 is a flowchart illustrating a fault diagnosis process for a (+) side main relay according to the second embodiment. The block diagram which shows the structure of the relay failure diagnostic part of the relay failure diagnostic apparatus which concerns on Embodiment 3 of this invention. 10 is a flowchart showing a failure diagnosis process for the (−) side main relay in the third embodiment. 10 is a flowchart illustrating a fault diagnosis process for a (+) side main relay according to the third embodiment. 10 is a flowchart showing a failure diagnosis process for the (−) side main relay in the fourth embodiment. 10 is a flowchart illustrating a fault diagnosis process for a (+) side main relay according to the fourth embodiment. The figure which shows the ON / OFF timing of each signal at the time of the failure diagnosis process of each main relay of Embodiments 5-8, and the change of a battery charging current and a power supply voltage. 10 is a flowchart illustrating a failure diagnosis process for a (−) side main relay according to the fifth embodiment. 10 is a flowchart showing a fault diagnosis process for a (+) side main relay in the fifth embodiment. 10 is a flowchart showing a failure diagnosis process of a (−) side main relay in Embodiment 6. 10 is a flowchart showing a fault diagnosis process for the (+) side main relay according to the sixth embodiment. 10 is a flowchart showing a failure diagnosis process of a (−) side main relay in the seventh embodiment. 10 is a flowchart showing a fault diagnosis process for a (+) side main relay in the seventh embodiment. 10 is a flowchart illustrating a failure diagnosis process for a (−) side main relay according to an eighth embodiment. 10 is a flowchart showing a fault diagnosis process for the (+) side main relay according to the eighth embodiment.

Hereinafter, the present invention will be described based on the illustrated embodiments.
<Embodiment 1>
FIG. 1 is a diagram showing a schematic configuration when the relay failure diagnosis apparatus according to Embodiment 1 of the present invention is applied to a drive system of an electric vehicle (electric vehicle in this embodiment).

  As shown in FIG. 1, the drive system of the electric vehicle includes an inverter 2 as a first load that drives a travel drive motor (for example, a three-phase AC motor) 1, and power for supplying power to the inverter 2. A high-power battery (DC power supply) 3 such as a lithium ion battery; a negative-side main relay (hereinafter referred to as “(−)-side main relay”) 5 connected to a negative-side power line 4 between the inverter 2 and the high-power battery 3; The positive main relay (hereinafter referred to as “(+) main relay”) 7 connected to the positive power line 6 between the inverter 2 and the high voltage battery 3 and the (−) main relay 5 are connected in parallel. And a DC / DC converter 9 as a second load having an input side connected between the negative power line 4 and the positive power line 6. The inverter 2 and the DC / DC converter 9 are connected in parallel.

  The inverter 2 converts DC power supplied from the high-power battery 3 into AC power, and supplies the converted AC power to the motor 1. The inverter 2 is connected to a control device (not shown) for switching control of a switching element (not shown) for rotating the motor 1 at a desired rotational speed.

  The (+) side main relay 7 that connects / cuts off the positive power line 6, the (−) side main relay 5 that connects / cuts off the negative power line 4, and the precharge relay 8 are turned on from the relay control unit 10. The connection / disconnection is controlled based on the / OFF signal. Note that the precharge relay 8 is provided with the (−) side main relay 5 in order to prevent a high voltage from being suddenly applied to the (−) side main relay 5 at the time of starting to connect the high voltage battery 3 and the inverter 2. It is a relay connected before connecting. Further, the (−) side main relay 5, the (+) side main relay 7, and the precharge relay 8 are welded to each main relay ((−) side main relay 5, (+) side main relay 7). A relay failure diagnosis unit 11 for diagnosing whether or not is connected is connected.

  The DC / DC converter 9 steps down the direct-current power supplied from the high voltage battery 3 based on the drive command signal from the converter drive control unit 12 and supplies it to auxiliary equipment (not shown) such as a vehicle electrical system. In the present embodiment, a relay failure diagnosis device 13 is configured by the relay control unit 10, the relay failure diagnosis unit 11, and the converter drive control unit 12. As the relay failure diagnosis device 13, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an input / output interface can be used.

  The relay failure diagnosis device 13 is connected to a power source battery (secondary battery) 14 of this device. The power supply voltage of the power supply battery 14 is, for example, 14V. Further, the output side of the DC / DC converter 9 and the power supply battery 14 are connected, and the battery charging current (hereinafter referred to as “charging current”) to the power supply battery 14 when the DC / DC converter 9 is driven is connected between them. Is connected to the ammeter 15.

  As shown in FIG. 2, the relay failure diagnosis unit 11 includes a diagnosis permission determination unit 20 that determines whether or not diagnosis of each main relay ((−) side main relay 5, (+) side main relay 7) is permitted, A drive command unit 21 that outputs a drive command signal to the converter drive control unit 12 when the diagnosis permission determination unit 20 determines diagnosis permission, and each main relay ((−) side when the diagnosis permission determination unit 20 determines diagnosis permission. A parameter calculation unit 22 that calculates parameters used for failure diagnosis of the main relay 5 and the (+) side main relay 7), and whether or not the relay is welded based on the parameters calculated by the parameter calculation unit 22 is determined. It has the determination part 23 to perform (details are mentioned later).

  Next, failure diagnosis processing of each main relay ((−) side main relay 5 and (+) side main relay 7) by the relay failure diagnosis unit 11 will be described. In the failure diagnosis processing of the present embodiment, the abnormality (failure) occurs in the inverter 2 and the main relays (the (−) side main relay 5 and the (+) side main relay 7) that are kept connected are connected to the relay control unit. This is performed after the forcible cut-off process is performed by a cut-off signal from a control unit (not shown) of a system different from 10.

  When the main relays ((−) side main relay 5 and (+) side main relay 7) are connected (ON), a current of a predetermined ampere flows, so that the atmosphere at the moment each main relay is forcibly cut off. There is a possibility that a welding failure may occur in each main relay due to generation of sparks due to discharge. For this reason, when each main relay is forcibly cut off, performing a failure diagnosis process for each main relay is also beneficial for improving the reliability of the entire drive system of the electric vehicle.

  FIG. 3 shows the ON / OFF timing of each signal and the change in battery charging current and power supply voltage (power supply voltage supplied to the relay failure diagnosis device 13) during failure diagnosis processing of each main relay of the present embodiment. 4 is a flowchart showing a failure diagnosis process for the (−) side main relay 5 in the present embodiment, and FIG. 5 is a flowchart showing a failure diagnosis process for the (+) side main relay 7 in the present embodiment. In FIG. 3, before time t1 (left side in FIG. 3), when each main relay is connected and held without abnormality (failure) in the inverter 2, after time t1 (right side in FIG. 3), This shows a failure diagnosis process for each main relay after an abnormality (failure) occurs in the inverter 2 and each main relay is forcibly cut off.

<Failure diagnosis processing of (-) side main relay 5>
After an abnormality (failure) occurs in the inverter 2 and each main relay (the (−) side main relay 5 and the (+) side main relay 7) that has been kept connected is forcibly cut off, FIG. As shown in FIG. 4, at time t <b> 1, an OFF (cutoff) signal is output from the relay control unit 10 to the (−) side main relay 5, and a drive stop signal (from the converter drive control unit 12 to the DC / DC converter 9). OFF signal) is output (step S1 in FIG. 4). At time t1, an ON (connection) signal is output to the (+) side main relay 7, and an OFF (cutoff) signal is output to the precharge relay 8.

  Based on the ON / OFF signal output from the relay control unit 10 at this time, the diagnosis permission determination unit 20 of the relay failure diagnosis unit 11 sends an ON signal to the (+) side main relay 7 and a (−) side main. When the OFF signal is output to the relay 5 and the OFF signal is output to the precharge relay 8, it is determined that the condition for permitting diagnosis of the (−) side main relay 5 is satisfied (step S <b> 2: YES), and the drive command unit 21. Outputs a failure diagnosis start signal. The drive command unit 21 outputs a drive command signal (ON signal) to the converter drive control unit 12 based on the input failure diagnosis start signal (time t2 in FIG. 3), and drives the DC / DC converter 9 (step). S3).

  At this time, a charging current value (charging current value at the time of failure diagnosis) measured by the ammeter 15 when the DC / DC converter 9 is driven is input to the parameter calculation unit 22 of the relay failure diagnosis unit 11. The parameter calculation unit 22 indicates that when the DC / DC converter 9 is driven at a normal time when no welding occurs in each main relay ((−) side main relay 5 and (+) side main relay 7). The charging current value (normal charging current value) is stored. Thus, in the present embodiment, the change in the output current from the DC / DC converter 9 when the DC / DC converter 9 is driven can be grasped by the charging current value measured by the ammeter 15.

  Then, the parameter calculation unit 22 calculates an increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven (time t2) from the charging current value at the time of the failure diagnosis and the charging current value at the time of normality. It is calculated as a parameter (step S4). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the charging current as the parameter calculated in step S4 is equal to or greater than a preset threshold value (step S5).

  When the increase value (or rate of increase) of the charging current as a parameter is greater than or equal to the threshold value in step S5 (step S5: YES), it is assumed that the (−) side main relay 5 has failed due to welding. Determination is made (step S6). Further, when the increase value (or rate of increase) of the charging current as a parameter is less than the threshold value in step S5 (step S5: NO), it is assumed that the (−) side main relay 5 is not welded and is normal. Determination is made (step S7).

  In step S6, after determining that the (−) side main relay 5 is welded (failed), an OFF signal is output from the relay control unit 10 to the (+) side main relay 7 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to time t3 in FIG. 3 (step S5), when the (−) side main relay 5 is out of order (welded), the value of the charging current rises above the threshold value from the normal time.

<Failure diagnosis processing of (+) side main relay 7>
As shown in FIG. 3, at the start of failure diagnosis of the (+) side main relay 7 performed after the failure diagnosis processing of the (−) side main relay 5, the relay control unit 10 switches to the precharge relay 8 at time t4. An ON (connection) signal is output (step S11 in FIG. 5).

  Based on the ON / OFF signal output from the relay control unit 10 at this time, the diagnosis permission determination unit 20 of the relay failure diagnosis unit 11 outputs an OFF signal to the (+) side main relay 7 and a (−) side main. When the OFF signal is output to the relay 5 and the ON signal is output to the precharge relay 8, it is determined that the condition for permitting diagnosis of the (+) side main relay 7 is satisfied (step S <b> 12: YES), and the drive command unit 21. Outputs a failure diagnosis start signal. The drive command unit 21 outputs a drive command signal (ON signal) to the converter drive control unit 12 based on the input failure diagnosis start signal (time t5 in FIG. 3), and drives the DC / DC converter 9 (step). S13).

  At this time, the parameter calculation unit 22 of the relay failure diagnosis unit 11 receives a charging current value at the time of failure diagnosis measured by the ammeter 15 when the DC / DC converter 9 is driven. The parameter calculation unit 22 stores the normal charging current value.

  Then, the parameter calculation unit 22 calculates an increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven (time t5) from the charging current value at the time of the failure diagnosis and the charging current value at the time of normality. It is calculated as a parameter (step S14). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the charging current as the parameter calculated in step S14 is greater than or equal to a preset threshold value (step S15).

  If the increase value (or rate of increase) of the charging current as a parameter is greater than or equal to the threshold value in step S15 (step S15: YES), if the (+) side main relay 7 is welded and has failed. Determination is made (step S16). Further, when the increase value (or increase rate) of the charging current as a parameter is less than the threshold value in step S15 (step S15: NO), it is assumed that the (+) side main relay 7 is normal without welding. Determination is made (step S17).

  In step S16, after determining that the (+) side main relay 7 has failed (welded), an OFF signal is output from the relay control unit 10 to the precharge relay 8 at time t6 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t5 to time t6 in FIG. 3 (step S16), when the (+) side main relay 7 is out of order (welded), the value of the charging current rises above the threshold value from the normal time.

  As described above, in this embodiment, an abnormality (failure) occurs in the inverter 2, and the main relays (the (−) side main relay 5 and the (+) side main relay 7) that are kept connected are forcibly cut off. Even after the processing, by determining whether or not the increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven is greater than or equal to the threshold value, the (−) side main relay 5 and ( It is possible to diagnose whether welding failure has occurred individually for the +) side main relay 7. Therefore, the reliability of the entire drive system of the electric vehicle can be improved.

<Embodiment 2>
In the first embodiment, by determining whether or not the increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven is equal to or greater than the threshold value, the (−) side main relay 5 and (+ In the present embodiment, the power supplied from the power battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven is used. By determining whether or not the voltage increase value (or rate of increase) is equal to or greater than a threshold value, welding (failure) diagnosis is performed on the (−) side main relay 5 and the (+) side main relay 7. . Others are the same as in the first embodiment. Hereinafter, failure diagnosis processing of the (−) side main relay 5 and the (+) side main relay 7 in the present embodiment will be described with reference to the flowcharts of FIGS. 6 and 7.

<Failure diagnosis processing of (-) side main relay 5>
FIG. 6 is a flowchart showing a failure diagnosis process of the (−) side main relay 5 in the present embodiment.

  The processing operations from the steps S21 to S23 of the present embodiment are the same as the processing operations from the steps S1 to S3 of the first embodiment shown in FIG.

  In step S23, the parameter calculation unit 22 of the relay failure diagnosis unit 11 supplies the power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. ) Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown).

  The parameter calculation unit 22 indicates that when the DC / DC converter 9 is driven at a normal time when no welding occurs in each main relay ((−) side main relay 5 and (+) side main relay 7). The power supply voltage value (normal power supply voltage value) supplied from the power supply battery 14 to the relay failure diagnosis device 13 is stored. As described above, in the present embodiment, the change in the output current from the DC / DC converter 9 during the driving of the DC / DC converter 9 is detected from the power supply battery 14 when the DC / DC converter 9 is driven. This can be grasped by the power supply voltage value supplied to the device 13.

  Then, the parameter calculation unit 22 calculates the power supply voltage at the time of failure diagnosis at the time of driving the DC / DC converter 9 (time t2: see FIG. 3) from the charging current value at the time of failure diagnosis and the power supply voltage value at the time of normality. The increase value (or increase rate) is calculated as a parameter (step S24). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the power supply voltage as the parameter calculated in step S24 is equal to or greater than a preset threshold value (step S25).

  When the increase value (or rate of increase) of the power supply voltage as a parameter is greater than or equal to the threshold value in step S25 (step S25: YES), if the (−) side main relay 5 is welded and has failed. Determination is made (step S26). If the increase value (or rate of increase) of the power supply voltage as a parameter is less than the threshold value in step S25 (step S25: NO), it is assumed that the (−) side main relay 5 is not welded and is normal. Determination is made (step S27).

  In step S26, after determining that the (−) side main relay 5 has failed (welded), an OFF signal is output from the relay control unit 10 to the (+) side main relay 7 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, during the period from time t2 to time t3 in FIG. 3 (when the failure is determined in step S26), when the (−) side main relay 5 has failed (welded), the value of the power supply voltage at the time of failure diagnosis is It rises above the threshold from normal.

<Failure diagnosis processing of (+) side main relay 7>
FIG. 7 is a flowchart showing a failure diagnosis process of the (+) side main relay 7 in the present embodiment.

  The processing operations from the steps S31 to S33 of the present embodiment are the same as the processing operations from the steps S11 to S13 of the first embodiment shown in FIG.

  In step S23, the parameter calculation unit 22 of the relay failure diagnosis unit 11 supplies the power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. ) Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown).

  The parameter calculation unit 22 indicates that when the DC / DC converter 9 is driven at a normal time when no welding occurs in each main relay ((−) side main relay 5 and (+) side main relay 7). The power supply voltage value (normal power supply voltage value) supplied from the power supply battery 14 to the relay failure diagnosis device 13 is stored.

  Then, the parameter calculation unit 22 calculates the power supply voltage at the time of failure diagnosis at the time of driving the DC / DC converter 9 (time t2: see FIG. 3) from the charging current value at the time of failure diagnosis and the power supply voltage value at the time of normality. The increase value (or increase rate) is calculated as a parameter (step S34). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the power supply voltage as the parameter calculated in step S34 is greater than or equal to a preset threshold value (step S35).

  If the increase value (or rate of increase) of the power supply voltage as a parameter is greater than or equal to the threshold value in step S35 (step S35: YES), it is assumed that the (+) side main relay 7 has failed due to welding. Determination is made (step S36). In addition, when the increase value (or rate of increase) of the power supply voltage as a parameter is less than the threshold value in step S35 (step S35: NO), it is assumed that the (+) side main relay 7 is normal without welding. Determination is made (step S37).

  In step S36, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an OFF signal to the precharge relay 8 at time t6 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, during the period from time t5 to time t6 in FIG. 3 (step S35), when the (+) side main relay 7 is faulty (welded), the power supply voltage value at the time of fault diagnosis exceeds the threshold value from the normal time. To rise.

  As described above, in this embodiment, an abnormality (failure) occurs in the inverter 2, and the main relays (the (−) side main relay 5 and the (+) side main relay 7) that are kept connected are forcibly cut off. Even after the processing, whether or not the increase value (or rate of increase) of the power supply voltage supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven is greater than or equal to the threshold value. By determining, it is possible to diagnose whether the (−) side main relay 5 and the (+) side main relay 7 are individually failed (welded).

  It should be noted that an increase value (or rate of increase) of the charging current when the DC / DC converter 9 in the first embodiment is driven and a relay failure diagnosis from the power battery 14 when the DC / DC converter 9 in the second embodiment is driven. By determining whether or not both of the rising values (or increasing rates) of the power supply voltage supplied to the device 13 are equal to or greater than the threshold values, the (−) side main relay 5 and the (+) side main relay 7 are determined. Thus, a configuration for diagnosing failure (welding) may be used.

<Embodiment 3>
FIG. 8 is a block diagram illustrating a configuration of a relay failure diagnosis unit of the relay failure diagnosis apparatus according to the third embodiment of the present invention.

  As shown in FIG. 8, the relay failure diagnosis unit 11a of the present embodiment determines whether to permit failure diagnosis of each main relay ((−) side main relay 5 and (+) side main relay 7). A diagnosis permission determination unit 20 to perform, a drive command unit 21 that outputs a drive command to the converter drive control unit 12 when the diagnosis permission determination unit 20 determines to permit failure diagnosis, and a diagnosis permission determination unit 20 When it is determined that the failure diagnosis is permitted, a determination unit 23 that determines a relay failure based on the charging current value when the DC / DC converter 9 is driven is provided. Other configurations are the same as those of the first embodiment, and redundant description is omitted.

  Hereinafter, failure diagnosis processing of the (−) side main relay 5 and the (+) side main relay 7 in the present embodiment will be described with reference to the flowcharts of FIGS. 9 and 10.

<Failure diagnosis processing of (-) side main relay 5>
FIG. 9 is a flowchart showing a failure diagnosis process of the (−) side main relay 5 in the present embodiment.

  The processing operations from the steps S41 to S43 in the present embodiment are the same as the processing operations from the steps S1 to S3 in the first embodiment shown in FIG.

  In step S43, the charging current value (charging current value at the time of failure diagnosis) measured by the ammeter 15 when the DC / DC converter 9 is driven is input to the determination unit 23 of the relay failure diagnosis unit 11. The parameter calculation unit 22 indicates that when the DC / DC converter 9 is driven at a normal time when no welding occurs in each main relay ((−) side main relay 5 and (+) side main relay 7). The charging current value (normal charging current value) is stored.

  And the determination part 23 determines whether the charging current value at the time of the said failure diagnosis is more than the preset threshold value (step S44).

  If the charging current value at the time of failure diagnosis is greater than or equal to the threshold value in step S44 (step S44: YES), it is determined that the (−) side main relay 5 has failed due to welding (step S45). . If the charging current value at the time of failure diagnosis is less than the threshold value in step S45 (step S44: NO), it is determined that the (−) side main relay 5 is not welded and is normal (step S46). .

  In step S45, after determining that the (−) side main relay 5 has failed (welded), an OFF signal is output from the relay control unit 10 to the (+) side main relay 7 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to time t3 in FIG. 3 (step S44), when the (−) side main relay 5 is faulty (welded), the value of the charging current at the time of fault diagnosis is greater than or equal to the threshold value from the normal time. To rise.

<Failure diagnosis processing of (+) side main relay 7>
FIG. 10 is a flowchart showing a failure diagnosis process of the (+) side main relay 7 in the present embodiment.

  The processing operations from the steps S51 to S53 of the present embodiment are the same as the processing operations from the steps S11 to S13 of the first embodiment shown in FIG.

  In step S53, the charging current value (charging current value at the time of failure diagnosis) of the power supply battery 14 measured by the ammeter 15 when the DC / DC converter 9 is driven is input to the determination unit 23 of the relay failure diagnosis unit 11. Is done. The parameter calculation unit 22 indicates that when the DC / DC converter 9 is driven at a normal time when no welding occurs in each main relay ((−) side main relay 5 and (+) side main relay 7). The charging current value (normal charging current value) of the power supply battery 14 is stored.

  And the determination part 23 determines whether the charging current value at the time of the said failure diagnosis is more than the preset threshold value (step S54).

  If the charging current value at the time of failure diagnosis is greater than or equal to the threshold value in step S54 (step S54: YES), it is determined that the (+) side main relay 7 has failed due to welding (step S55). . Further, if the charging current value at the time of failure diagnosis is less than the threshold value in step S54 (step S54: NO), it is determined that the (+) side main relay 7 is normal without welding (step S56). .

  In step S55, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an OFF signal to the precharge relay 8 at time t6 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t5 to t6 in FIG. 3 (step S54), when the (+) side main relay 7 is faulty (welded), the value of the charging current at the time of fault diagnosis is greater than or equal to the threshold value from the normal time. To rise.

  As described above, in this embodiment, an abnormality (failure) occurs in the inverter 2, and the main relays (the (−) side main relay 5 and the (+) side main relay 7) that are kept connected are forcibly cut off. Even after the processing, by determining whether or not the charging current value of the power source battery 14 when the DC / DC converter 9 is driven is equal to or greater than the threshold value, the (−) side main relay 5 and the (+) It is possible to diagnose whether a failure (welding) has occurred with respect to the side main relay 7 individually.

<Embodiment 4>
In the third embodiment, it is determined whether or not the charging current value of the power source battery 14 when the DC / DC converter 9 is driven is greater than or equal to the threshold value, so that the (−) side main relay 5 and the (+) side In the present embodiment, the power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven is configured to diagnose the failure (welding) with respect to the main relay 7. By determining whether or not is greater than or equal to a threshold value, the (−) side main relay 5 and the (+) side main relay 7 are diagnosed (failed). Others are the same as in the third embodiment. Hereinafter, failure diagnosis processing of the (−) side main relay 5 and the (+) side main relay 7 in the present embodiment will be described with reference to the flowcharts of FIGS. 11 and 12.

<Failure diagnosis processing of (-) side main relay 5>
FIG. 11 is a flowchart showing a failure diagnosis process of the (−) side main relay 5 in the present embodiment.

  The processing operations from the steps S61 to S63 of this embodiment are the same as the processing operations from the steps S1 to S3 of the first embodiment shown in FIG.

  In step S63, the determination unit 23 of the relay failure diagnosis unit 11 supplies the power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown).

  It should be noted that the determination unit 23 indicates that the main relay (the (−) side main relay 5, the (+) side main relay 7) is in a normal state where no welding has occurred and the DC / DC converter 9 is being driven. The power supply voltage value (normal power supply voltage value) supplied from the power supply battery 14 to the relay failure diagnosis device 13 is stored.

  And the determination part 23 determines whether the power supply voltage value at the time of the said failure diagnosis is more than the preset threshold value (step S64).

  If the power supply voltage value at the time of failure diagnosis is greater than or equal to the threshold value in step S64 (step S64: YES), it is determined that the (−) side main relay 5 has failed due to welding (step S65). . When the power supply voltage value at the time of failure diagnosis is less than the threshold value in step S64 (step S64: NO), it is determined that the (−) side main relay 5 is not welded and is normal (step S66). .

  In step S65, after determining that the (−) side main relay 5 has failed (welded), an OFF signal is output from the relay control unit 10 to the (+) side main relay 7 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to time t3 in FIG. 3 (step S64), when the (−) side main relay 5 has failed (welded), the value of the power supply voltage at the time of failure diagnosis is greater than or equal to the threshold value from the normal time. To rise.

<Failure diagnosis processing of (+) side main relay 7>
FIG. 12 is a flowchart showing a failure diagnosis process of the (+) side main relay 7 in the present embodiment.

  The processing operations from the steps S71 to S73 of this embodiment are the same as the processing operations from the steps S11 to S13 of the first embodiment shown in FIG.

  In step S73, the determination unit 23 of the relay failure diagnosis unit 11 supplies the power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown).

  It should be noted that the determination unit 23 indicates that the main relay (the (−) side main relay 5, the (+) side main relay 7) is in a normal state where no welding has occurred and the DC / DC converter 9 is being driven. The power supply voltage value (normal power supply voltage value) supplied from the power supply battery 14 to the relay failure diagnosis device 13 is stored.

  And the determination part 23 determines whether the power supply voltage value at the time of the said failure diagnosis is more than the preset threshold value (step S74).

  If the power supply voltage value at the time of failure diagnosis is greater than or equal to the threshold value in step S74 (step S74: YES), it is determined that the (+) side main relay 7 has failed due to welding (step S75). . Further, when the power supply voltage value at the time of failure diagnosis is less than the threshold value in step S74 (step S74: NO), it is determined that the (+) side main relay 7 is normal without welding (step S76). .

  In step S75, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an OFF signal to the precharge relay 8 at time t6 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t5 to t6 in FIG. 3 (step S74), when the (+) side main relay 7 is faulty (welded), the value of the power supply voltage at the time of fault diagnosis is greater than or equal to the threshold value from the normal time. To rise.

  As described above, in this embodiment, an abnormality (failure) occurs in the inverter 2, and the main relays (the (−) side main relay 5 and the (+) side main relay 7) that are kept connected are forcibly cut off. Even after the processing, by determining whether or not the power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven is equal to or larger than the threshold value (− It is possible to diagnose whether or not the main relay 5 and the positive main relay 7 are individually broken (welded).

  The charging current value when the DC / DC converter 9 in the third embodiment is driven, and the power supplied from the power battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 in the fourth embodiment is driven. A configuration in which a failure (welding) diagnosis is performed on the (−) side main relay 5 and the (+) side main relay 7 by determining whether both of the voltage values are equal to or greater than a threshold value may be employed.

  In the above-described first to fourth embodiments, an abnormality (failure) occurs in the inverter 2, and the main relays (the (−) side main relay 5 and the (+) side main relay 7) that are kept connected are forcibly cut off. In this example, failure diagnosis of each main relay is performed after the processing, but before the ignition switch (ING) of the electric vehicle (electric vehicle in this embodiment) is turned on to drive the driving motor 1. A failure diagnosis of each main relay may be performed during the starting process.

  In the following fifth to eighth embodiments, a failure diagnosis process ((−) side main relay 5, (+) side main relay 7) of each main relay during the activation process will be described.

<Embodiment 5>
FIG. 13 is a diagram showing the ON / OFF timing of each signal and the change in the battery charging current and the power supply voltage during the failure diagnosis process of each main relay according to this embodiment, and FIG. 14 is the (−) side in this embodiment. FIG. 15 is a flowchart showing a failure diagnosis process for the (+) side main relay 7 in the present embodiment.

<Failure diagnosis processing of (-) side main relay 5>
As shown in FIGS. 13 and 14, the ignition switch (ING) is turned on at time t1 (step S101), and during the start-up process before driving the motor 1, from the relay control unit 10 to the (−) side at time t2. An ON (connection) signal is output to the main relay 5 and a drive signal (ON signal) is output from the converter drive control unit 12 to the DC / DC converter 9 (step S102). The (+) side main relay 7 and the precharge relay 8 are output with an OFF (cutoff) signal.

  Then, based on the ON / OFF signal output from the relay control unit 10 at time t2, the diagnosis permission determination unit 20 of the relay failure diagnosis unit 11 outputs the OFF signal to the (+) side main relay 7 and the (−) side main. When the ON signal is output to the relay 5 and the OFF signal is output to the precharge relay 8, it is determined that the condition for permitting diagnosis of the (−) side main relay 5 is satisfied (step S103: YES), and the drive command unit 21 Outputs a failure diagnosis start signal. The drive command unit 21 outputs a drive command signal (ON signal) to the converter drive control unit 12 based on the input failure diagnosis start signal, and drives the DC / DC converter 9 (step S104).

  At this time, the charging current value (charging current value at the time of failure diagnosis) of the power source battery 14 measured by the ammeter 15 when the DC / DC converter 9 is driven is input to the parameter calculation unit 22 of the relay failure diagnosis unit 11. Is done. The parameter calculation unit 22 includes a DC / DC converter 9 in a normal state in which no welding has occurred in each main relay ((−) side main relay 5 and (+) side main relay 7) during the previous activation process. The charging current value (normal charging current value) when is driven is stored.

  Then, the parameter calculation unit 22 increases the charging current value (or rate of increase) when the DC / DC converter 9 is driven (time t2) from the charging current value at the time of failure diagnosis and the charging current value at the time of normal operation. Is calculated as a parameter (step S105). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the charging current as the parameter calculated in step S105 is greater than or equal to a preset threshold value (step S106).

  When the increase value (or increase rate) of the charging current as a parameter is greater than or equal to the threshold value in step S106 (step S106: YES), the (−) side main relay 5 is welded and has a failure. Determination is made (step S107). In addition, when the increase value (or increase rate) of the charging current as a parameter is less than the threshold value in step S106 (step S106: NO), it is assumed that the (−) side main relay 5 is normal without welding. Determination is made (step S108).

  In step S107, after determining that the (−) side main relay 5 has failed (welded), an OFF signal is output from the relay control unit 10 to the (−) side main relay 5 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to time t3 in FIG. 13 (step S106), when the (−) side main relay 5 is faulty (welded), the value of the charging current rises to a threshold value or more from the normal time.

<Failure diagnosis processing of (+) side main relay 7>
As shown in FIG. 15, at the time of starting the failure diagnosis of the (+) side main relay 7 performed after the failure diagnosis process of the (−) side main relay 5, the relay control unit 10 sends the (+) side main relay at time t4. An ON signal is output to the relay 7 and a drive command signal (ON signal) is output from the converter drive control unit 12 to the DC / DC converter 9 (step S111 in FIG. 15).

  Then, based on the ON / OFF signal output from the relay control unit 10 at this time (time t4), the diagnosis permission determination unit 20 of the relay failure diagnosis unit 11 outputs an ON signal to the (+) side main relay 7, ( -) When the OFF signal is output to the side main relay 5 and the OFF signal is output to the precharge relay 8, it is determined that the condition for permitting diagnosis of the (+) side main relay 7 is satisfied (step S112: YES). A failure diagnosis start signal is output to the drive command unit 21. The drive command unit 21 outputs a drive command signal (ON signal) to the converter drive control unit 12 based on the input failure diagnosis start signal, and drives the DC / DC converter 9 (step S113).

  At this time, the charging current value (charging current value at the time of failure diagnosis) of the power source battery 14 measured by the ammeter 15 when the DC / DC converter 9 is driven is input to the parameter calculation unit 22 of the relay failure diagnosis unit 11. Is done. The parameter calculation unit 22 includes a DC / DC converter 9 in a normal state in which no welding has occurred in each main relay ((−) side main relay 5 and (+) side main relay 7) during the previous activation process. The charging current value (normal charging current value) when is driven is stored.

  Then, the parameter calculation unit 22 calculates an increase value of the charging current of the power supply battery 14 when the DC / DC converter 9 is driven (time t4) from the charging current value at the time of failure diagnosis and the charging current value at the time of normality (time t4). Alternatively, the rate of increase is calculated as a parameter (step S114). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the charging current as the parameter calculated in step S114 is greater than or equal to a preset threshold value (step S115).

  When the increase value (or rate of increase) of the charging current as a parameter is greater than or equal to the threshold value in step S115 (step S115: YES), it is assumed that the (+) side main relay 7 has failed due to welding. Determination is made (step S116). Further, when the increase value (or increase rate) of the charging current as a parameter is less than the threshold value in step S115 (step S115: NO), it is assumed that the (+) side main relay 7 is normal without welding. Determination is made (step S117).

  In step S116, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an ON signal to the precharge relay 8 at time t5 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t4 to time t5 in FIG. 13 (step S115 in FIG. 15), when the (+) side main relay 7 is out of order (welding), the value of the charging current rises above the threshold value from the normal time. To do.

  In step S117, when it is diagnosed that each main relay ((−) side main relay 5 and (+) side main relay 7) has no failure (welding) and is normal, the relay control unit at time t6. 10 outputs an ON signal to the (−) side main relay 5, outputs an OFF signal to the precharge relay 8 at time t 7, and holds the negative power line 4 and the positive power line 6 in a connected state. Then, the activation process is terminated. After the start-up process is completed, the inverter 2 converts the DC power supplied from the high-power battery 3 into AC power to drive the motor 1, and further drives the DC / DC converter 9 to drive auxiliary equipment such as a vehicle electrical system. Actuate class (not shown).

  Thus, in this embodiment, whether or not the increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven is greater than or equal to the threshold value even during the startup process before driving the motor 1. It is possible to diagnose whether the (−) side main relay 5 and the (+) side main relay 7 are individually broken (welded).

<Embodiment 6>
In the fifth embodiment, by determining whether or not the increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven is equal to or greater than the threshold value, the (−) side main relay 5 and (+ In the present embodiment, the power supplied from the power battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven is used. By determining whether or not the voltage increase value (or rate of increase) is equal to or greater than a threshold value, the (−) side main relay 5 and the (+) side main relay 7 are diagnosed (failed). . Others are the same as in the fifth embodiment. Hereinafter, failure diagnosis processing of the (−) side main relay 5 and the (+) side main relay 7 in the present embodiment will be described with reference to the flowcharts of FIGS. 16 and 17.

<Failure diagnosis processing of (-) side main relay 5>
FIG. 16 is a flowchart showing a failure diagnosis process of the (−) side main relay 5 in the present embodiment.

  The processing operations from the steps S121 to S124 of this embodiment are the same as the processing operations from the steps S101 to S104 of the fifth embodiment shown in FIG.

  In step S124, the parameter calculation unit 22 of the relay failure diagnosis unit 11 includes a power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. ) Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown).

  The parameter calculation unit 22 includes a DC / DC converter 9 in a normal state in which no welding has occurred in each main relay ((−) side main relay 5 and (+) side main relay 7) during the previous activation process. The power supply voltage value (normal power supply voltage value) when is driven is stored.

  The parameter calculation unit 22 then increases the power supply voltage value of the power supply battery 14 when the DC / DC converter 9 is driven (time t2) from the power supply voltage value at the time of failure diagnosis and the power supply voltage value at the time of normal operation. (Or rate of increase) is calculated as a parameter (step S125). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the power supply voltage as the parameter calculated in step S125 is equal to or greater than a preset threshold value (step S126).

  In step S126, if the increase value (or rate of increase) of the power supply voltage as a parameter is greater than or equal to the threshold value (step S126: YES), the (−) side main relay 5 has been welded and has failed. Determination is made (step S127). If the increase value (or rate of increase) of the power supply voltage as a parameter is less than the threshold value in step S126 (step S126: NO), it is assumed that the (−) side main relay 5 is not welded and is normal. Determination is made (step S128).

  In step S127, after determining that the (−) side main relay 5 has failed (welded), an OFF signal is output from the relay control unit 10 to the (−) side main relay 5 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to time t3 in FIG. 13 (step S126), when the (−) side main relay 5 is in failure (welding), the power supply voltage value at the time of failure diagnosis is higher than the threshold value from the normal time. To rise.

<Failure diagnosis processing of (+) side main relay 7>
FIG. 17 is a flowchart showing a failure diagnosis process of the (+) side main relay 7 in the present embodiment.

  The processing operations from the steps S131 to S133 of this embodiment are the same as the processing operations from the steps S111 to S113 of the fifth embodiment shown in FIG.

  In step S133, the parameter calculation unit 22 of the relay failure diagnosis unit 11 includes a power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. ) Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown).

  The parameter calculation unit 22 includes a DC / DC converter 9 in a normal state in which no welding has occurred in each main relay ((−) side main relay 5 and (+) side main relay 7) during the previous activation process. The power supply voltage value (normal power supply voltage value) when is driven is stored.

  Then, the parameter calculation unit 22 uses the power supply voltage value at the time of the failure diagnosis and the power supply voltage value at the normal time to increase the power supply voltage value at the time of driving the DC / DC converter 9 (time t4 in FIG. 13) (or (Increase rate) is calculated as a parameter (step S134). Then, the determination unit 23 of the relay failure diagnosis unit 11 determines whether or not the increase value (or increase rate) of the power supply voltage as the parameter calculated in step S134 is equal to or greater than a preset threshold value (step S135).

  If the increase value (or rate of increase) of the power supply voltage as a parameter is greater than or equal to the threshold value in step S135 (step S135: YES), it is assumed that the (+) side main relay 7 has failed due to welding. Determination is made (step S136). If the increase value (or rate of increase) of the power supply voltage as a parameter is less than the threshold value in step S135 (step S135: NO), it is assumed that the (+) side main relay 7 is normal without welding. Determination is made (step S137).

  In step S136, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an ON signal to the precharge relay 8 at time t5 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, during the period from time t4 to t5 in FIG. 13 (step S135 in FIG. 15), when the (+) side main relay 7 is out of order (welded), the value of the power supply voltage of the power supply battery 14 is normal. Rises above the threshold.

  In step S137, when it is diagnosed that each main relay ((−) side main relay 5 and (+) side main relay 7) is normal without any failure (welding), the relay control unit at time t6. 10 outputs an ON signal to the (−) side main relay 5, outputs an OFF signal to the precharge relay 8 at time t 7, and holds the negative power line 4 and the positive power line 6 in a connected state. Then, the activation process is terminated. After the start-up process is completed, the inverter 2 converts the DC power supplied from the high-power battery 3 into AC power to drive the motor 1, and further drives the DC / DC converter 9 to drive auxiliary equipment such as a vehicle electrical system. Actuate class (not shown).

  Thus, in this embodiment, even during the startup process before driving the motor 1, the increase value (or increase rate) of the power supply voltage of the power supply battery 14 when the DC / DC converter 9 is driven is greater than or equal to the threshold value. It is possible to diagnose whether or not the (−) side main relay 5 and the (+) side main relay 7 are individually broken (welded).

  It should be noted that a relay failure occurs from the rising value (or rate of increase) of the charging current value when the DC / DC converter 9 in the fifth embodiment is driven and the power supply battery 14 when the DC / DC converter 9 in the sixth embodiment is driven. By determining whether or not both of the increase values (or increase rates) of the power supply voltage value supplied to the diagnostic device 13 are equal to or greater than the threshold values, the (−) side main relay 5 and the (+) side main relay 7 are determined. It is also possible to employ a configuration for diagnosing failure (welding).

<Embodiment 7>
In this embodiment, it has the relay failure diagnosis part 11a shown in FIG.

  In the fifth embodiment, by determining whether or not the increase value (or increase rate) of the charging current when the DC / DC converter 9 is driven is equal to or greater than the threshold value, the (−) side main relay 5 and (+ However, in this embodiment, the power supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven is used. By determining whether or not the voltage is equal to or higher than a threshold value, a failure (welding) diagnosis is made on the (−) side main relay 5 and the (+) side main relay 7. Others are the same as in the fifth embodiment. Hereinafter, failure diagnosis processing of the (−) side main relay 5 and the (+) side main relay 7 in the present embodiment will be described with reference to the flowcharts of FIGS. 18 and 19.

<Failure diagnosis processing of (-) side main relay 5>
FIG. 18 is a flowchart showing a failure diagnosis process of the (−) side main relay 5 in the present embodiment.

  The processing operations from step S141 to S144 of the present embodiment are the same as the processing operations from step S101 to S104 of the first embodiment shown in FIG.

  In step S144, the determination unit 23 (see FIG. 9) of the relay failure diagnosis unit 11 receives the charging current value (charging current value at the time of failure diagnosis) measured by the ammeter 15 when the DC / DC converter 9 is driven. Is done. And the determination part 23 determines whether the charging current value at the time of the said failure diagnosis is more than the preset threshold value (step S145).

  If the charging current value is greater than or equal to the threshold value in step S145 (step S145: YES), it is determined that the (−) side main relay 5 has failed due to welding (step S146). If the charging current value is less than the threshold value in step S145 (step S145: NO), it is determined that the (−) side main relay 5 is not welded and is normal (step S147).

  After determining that the (−) side main relay 5 has failed (welded) in step S146, an OFF signal is output from the relay control unit 10 to the (−) side main relay 5 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to t3 in FIG. 13 (step S145), when the (−) side main relay 5 is out of order (welded), the value of the charging current of the power supply battery 14 is the threshold value from the normal time. It rises above.

<Failure diagnosis processing of (+) side main relay 7>
FIG. 19 is a flowchart showing a failure diagnosis process of the (+) side main relay 7 in the present embodiment.

  The processing operations from step S151 to S153 of the present embodiment are the same as the processing operations from step S111 to S113 of the fifth embodiment shown in FIG.

  In step S153, a charging current value (charging current value at failure diagnosis) measured by the ammeter 15 when the DC / DC converter 9 is driven is input to the determination unit 23 of the relay failure diagnosis unit 11. And the determination part 23 determines whether the charging current value at the time of the said failure diagnosis is more than the preset threshold value (step S154).

  If the charging current value at the time of failure diagnosis is greater than or equal to the threshold value in step S154 (step S145: YES), it is determined that the (+) side main relay 7 has failed due to welding (step S155). . If the charging current value at the time of failure diagnosis is less than the threshold value in step S154 (step S154: NO), it is determined that the (+) side main relay 7 is not welded and is normal (step S156). .

  In step S155, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an ON signal to the precharge relay 8 at time t5 in FIG. A drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t4 to time t5 in FIG. 13 (step S154 in FIG. 19), when the (+) side main relay 7 is out of order (welding), the value of the charging current rises above the threshold value from the normal time. To do.

  In step S156, when it is diagnosed that the (+) side main relay 7 is normal without any failure (welding), an ON signal is sent from the relay control unit 10 to the (−) side main relay 5 at time t6. At time t7, an OFF signal is output to the precharge relay 8, and the negative power line 4 and the positive power line 6 are held in a connected state, thereby completing the start-up process. After the start-up process is completed, the inverter 2 converts the DC power supplied from the high-power battery 3 into AC power to drive the motor 1, and further drives the DC / DC converter 9 to drive auxiliary equipment such as a vehicle electrical system. Actuate class (not shown).

  Thus, in the present embodiment, it is determined whether or not the charging current value of the power supply battery 14 when the DC / DC converter 9 is driven is equal to or greater than the threshold value even during the startup process before driving the motor 1. By doing so, it is possible to diagnose whether the (−) side main relay 5 and the (+) side main relay 7 are individually failed (welded).

<Embodiment 8>
In the seventh embodiment, by determining whether or not the charging current value when the DC / DC converter 9 is driven is equal to or larger than the threshold value, the (−) side main relay 5 and the (+) side main relay 7 are determined. In this embodiment, the power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is equal to or greater than the threshold value. It is the structure which diagnoses a failure (welding) with respect to the (-) side main relay 5 and the (+) side main relay 7 by determining. Others are the same as in the seventh embodiment. Hereinafter, failure diagnosis processing of the (−) side main relay 5 and the (+) side main relay 7 in the present embodiment will be described with reference to the flowcharts of FIGS. 20 and 21.

<Failure diagnosis processing of (-) side main relay 5>
FIG. 20 is a flowchart showing a failure diagnosis process of the (−) side main relay 5 in the present embodiment.

  The processing operations from step S161 to S164 in the present embodiment are the same as the processing operations from step S141 to S144 in the first embodiment shown in FIG.

  In step S164, the determination unit 23 (see FIG. 9) of the relay failure diagnosis unit 11 supplies the power supply voltage value (during failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. Power supply voltage value) is input. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown). And the determination part 23 determines whether the power supply voltage value at the time of the said failure diagnosis is more than the preset threshold value (step S165).

  If the power supply voltage value is greater than or equal to the threshold value in step S165 (step S165: YES), it is determined that the (−) side main relay 5 has failed due to welding (step S166). Further, when the power supply voltage value is less than the threshold value in step S165 (step S165: NO), it is determined that the (−) side main relay 5 is not welded and is normal (step S167).

  In step S166, after determining that the (−) side main relay 5 has failed (welded), an OFF signal is output from the relay control unit 10 to the (−) side main relay 5 at time t3 in FIG. At the same time, a drive stop signal (OFF signal) is output from the converter drive control unit 12 to the DC / DC converter 9. Therefore, in the period from time t2 to time t3 in FIG. 13 (the step S165), when the (−) side main relay 5 is out of order (welded), the value of the power supply voltage rises above the threshold value from the normal time.

<Failure diagnosis processing of (+) side main relay 7>
FIG. 21 is a flowchart showing a failure diagnosis process of the (+) side main relay 7 in the present embodiment.

  The processing operations from Steps S171 to S173 of the present embodiment are the same as the processing operations from Steps S111 to S113 of the seventh embodiment shown in FIG.

  In step S173, the determination unit 23 of the relay failure diagnosis unit 11 supplies the power supply voltage value (power supply voltage value at the time of failure diagnosis) supplied from the power supply battery 14 to the relay failure diagnosis device 13 when the DC / DC converter 9 is driven. Is entered. The power supply voltage value supplied from the power supply battery 14 to the relay failure diagnosis device 13 is measured by a voltmeter (not shown). And the determination part 23 determines whether the power supply voltage value at the time of the said failure diagnosis is more than the preset threshold value (step S174).

  If the power supply voltage value at the time of failure diagnosis is greater than or equal to the threshold value in step S174 (step S174: YES), it is determined that the (+) side main relay 7 has failed due to welding (step S175). . Further, when the power supply voltage value at the time of failure diagnosis is less than the threshold value in step S174 (step S174: NO), it is determined that the (+) side main relay 7 is not welded and is normal (step S176). .

  In step S175, after determining that the (+) side main relay 7 has failed (welded), the relay control unit 10 outputs an ON signal to the precharge relay 8 at time t5 in FIG. A drive stop signal (OFF signal) is output from the drive command unit 21 to the DC / DC converter 9. Therefore, in the period from time t4 to t5 in FIG. 13 (step S174 in FIG. 20), when the (+) side main relay 7 has failed (welded), the value of the power supply voltage at the time of failure diagnosis is normal. Rise above the threshold.

  If it is diagnosed in step S176 that the (+) side main relay 7 is normal without any failure (welding), an ON signal is sent from the relay control unit 10 to the (−) side main relay 5 at time t6. At time t7, an OFF signal is output to the precharge relay 8, and the negative power line 4 and the positive power line 6 are held in a connected state, thereby completing the start-up process. After the start-up process is completed, the inverter 2 converts the DC power supplied from the high-power battery 3 into AC power to drive the motor 1, and further drives the DC / DC converter 9 to drive auxiliary equipment such as a vehicle electrical system. Actuate class (not shown).

  Thus, in this embodiment, even during the startup process before driving the motor 1, it is determined whether or not the power supply voltage value when the DC / DC converter 9 is driven is greater than or equal to the threshold value. It is possible to diagnose whether the −) side main relay 5 and the (+) side main relay 7 are individually broken (welded).

  Whether or not both the charging current value when the DC / DC converter 9 in the seventh embodiment is driven and the power supply voltage value when the DC / DC converter 9 in the eighth embodiment is driven are equal to or more than a threshold value, respectively. By determining, it may be configured that a failure (welding) diagnosis is performed on the (−) side main relay 5 and the (+) side main relay 7.

  In each of the above-described embodiments, the DC / DC converter 9 is provided as the second load. However, the present invention is not limited to this, and an air compressor or the like may be used. In each of the above-described embodiments, an example of an electric vehicle is shown as an electric vehicle. However, the present invention can be similarly applied to a hybrid vehicle including a motor and an engine as a driving source.

DESCRIPTION OF SYMBOLS 1 Motor 2 Inverter 3 High power battery 4 Negative side power line 5 Negative side main relay 6 Positive side power line 7 Positive side main relay 8 Precharge relay 9 DC / DC converter 10 Relay control part 11, 11a Relay fault diagnosis part 12 Converter drive Control unit 13 Relay failure diagnosis device 14 Power supply battery 15 Ammeter

Claims (5)

A first relay that connects / cuts off a first power line that connects a positive side of a DC power source and a first load, and a second relay that connects the negative side of the DC power source and the first load In the relay failure diagnosis device for diagnosing the presence or absence of a welding failure with respect to the second relay for connecting / cutting off the power line,
Relay control means for outputting an on / off signal to each of the first and second relays to control connection / disconnection of each of the first and second relays;
A drive for connecting a second load in parallel with the first load between the first power line and the second power line and outputting a drive command signal for driving the second load Means,
When the relay control means individually outputs an on signal or an off signal to each of the first and second relays and outputs a drive command signal from the drive means to the second load, Relay failure diagnosis means for diagnosing whether or not each of the first and second relays is welded based on a change in output current or / and output voltage from the second load. Relay failure diagnosis device.   The relay failure diagnosing means is configured to weld each of the first and second relays when the first load fails and the first and second relays are forcibly disconnected from the connected state. The relay failure diagnosis device according to claim 1, wherein whether or not the relay failure is detected is diagnosed.   The relay failure diagnosing means diagnoses whether or not welding has occurred in the first and second relays before starting the first and second relays from a disconnected state to a connected state. The relay failure diagnosis apparatus according to claim 1.   The relay failure diagnosing means is configured such that, for each of the first and second relays, an increase value or an increase rate of the output current or / and output voltage from the second load from a normal time is greater than or equal to a predetermined threshold value. The relay failure diagnosis apparatus according to claim 1, wherein when it is determined that there is a weld, a diagnosis is made that welding has occurred.   The relay failure diagnosing means has an output current or / and an output voltage value from the first load or the second load equal to or greater than a predetermined threshold for the first and second relays. The relay failure diagnosis apparatus according to any one of claims 1 to 3, wherein when the determination is made, it is diagnosed that welding has occurred.

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