JP2007329045A - Relay fault diagnostic system - Google Patents

Abstract

An object of the present invention is to improve diagnosis accuracy in failure diagnosis for diagnosing a relay failure.
A high voltage system includes at least a drive motor, a secondary battery, and a high voltage path. The first relays 15 to 17 are relays that can cut off the connection between the drive motor 11 and the secondary battery 13 via the high voltage path 14 according to the open / close state of the first relays 15 to 17. The insulation resistance sensor 30 is connected to the high voltage path 14 and is a coupling capacitor type sensor that detects an insulation resistance between the high voltage system 10 and the ground potential. The state changing unit 21 is connected to the side facing the insulation resistance sensor 30 via the first relays 15 to 17 in the high voltage path 14, and the capacitance between the high voltage system 10 and the ground potential. Or the insulation resistance is changed. The failure diagnosis unit 41 performs failure diagnosis of the first relays 15 to 17.
[Selection] Figure 1

Description

  The present invention relates to a relay failure diagnosis apparatus that diagnoses a failure of a relay.

  In vehicles equipped with high-voltage systems such as electric vehicles and fuel cell vehicles, there is a large negative effect due to electric leakage, and it is not connected to the ground for safety reasons. Therefore, it is necessary to detect insulation resistance to prevent electric leakage. There is. Therefore, an insulation resistance detection device that detects an insulation resistance between a high voltage system (such as a high voltage battery) and a ground (vehicle body) insulated from the high voltage system is known. In this insulation resistance detection device, a rectangular wave signal is output to a high voltage system via a detection resistor and a coupling capacitor, and the insulation resistance is detected based on the voltage fluctuation at the connection point between the coupling capacitor and the detection resistor. Is done.

For example, according to Patent Document 1, a diagnostic method is disclosed that uses an output value of an insulation resistance detection device to detect whether a relay of a high-voltage system is open-fixed or closed-fixed. . According to such a technique, the output value of the insulation resistance detection device in the combination of ON / OFF of the relays of each part is stored, and the output value is stored in advance (the impedance in the state where each relay is turned on). If the output value is not a value stored in advance, it is diagnosed that the relay is abnormal (failure).
JP-A-2005-149843

  However, according to the technique disclosed in Patent Document 1, when the insulation resistance of the device existing in the path of the high voltage system is deteriorated due to aging, the diagnosis is performed based on the impedance estimated in advance. This may become an error and lead to a misdiagnosis. Further, in the case where the high voltage system includes a fuel cell, the resistance and impedance of the liquid water of the fuel cell vary depending on environmental conditions such as the air temperature, which makes it difficult to ensure the accuracy of diagnosis.

  The present invention has been made in view of such circumstances, and an object of the present invention is to improve diagnosis accuracy in failure diagnosis for diagnosing a failure in a relay.

  In order to solve such a problem, the present invention provides a relay failure diagnosis apparatus having a high voltage system, a first relay, an insulation resistance sensor, a state change unit, and a failure diagnosis unit. Here, the high voltage system includes at least a load, a secondary battery, and a high voltage path that electrically connects the load and the secondary battery. A 1st relay is a relay which can interrupt | block the connection between the load and secondary battery via a high voltage path | route according to its own opening / closing state. The insulation resistance sensor is a coupling capacitor type sensor that is connected to a high voltage path and detects an insulation resistance between the high voltage system and a ground potential. The state change unit is connected to the side facing the insulation resistance sensor via the first relay in the high voltage path, and changes the capacitance or insulation resistance between the high voltage system and the ground potential. The failure diagnosis unit performs failure diagnosis of the first relay.

  Here, the failure diagnosing unit has a closed sticking diagnosis means, an open sticking diagnosis means, and a determination means. The closed adhesion diagnosis means is configured such that the insulation resistance detected by the insulation resistance sensor and the capacitance or the insulation resistance are changed by the state change unit in a state in which the open state is instructed to the first relay. Based on the difference from the insulation resistance detected by the sensor, the first relay is diagnosed as closed. The open adhesion diagnostic means is detected by the insulation resistance sensor detected by the insulation resistance sensor when the open state is instructed to the first relay, and detected by the insulation resistance sensor when the close state is instructed by the first relay. Based on the difference between the insulation resistance and the first relay, the first relay is diagnosed as being openly stuck. The determination means is conditioned on the condition that the first relay is diagnosed as not being closed and stuck by the closed sticking diagnosis means, and the first relay is diagnosed as not being stuck and stuck by the open sticking diagnosis means. It is determined that 1 relay has not failed.

  According to the present invention, it is diagnosed that the first relay is closed and stuck, and that the first relay is diagnosed as not being closed and stuck, and has been diagnosed as not being open and stuck. As a condition, it is determined that the first relay has not failed. This makes it possible to perform a diagnosis that comprehensively evaluates both the closed and open fixations, thereby improving the accuracy of failure diagnosis. Furthermore, in each diagnosis, the diagnosis can be made by relative comparison of the outputs of the insulation resistance sensors (that is, whether or not there is a difference between the outputs). Therefore, even when impedance and insulation resistance change over time, diagnosis can be performed with high accuracy.

  FIG. 1 is a configuration diagram of a fuel cell vehicle to which a relay failure diagnosis apparatus according to an embodiment of the present invention is applied. The relay failure diagnosis apparatus according to the present embodiment is applied to a fuel cell vehicle in which a fuel cell system that generates power by a chemical reaction between a fuel gas and an oxidant gas is mounted as a vehicle drive source.

  The relay failure diagnosis apparatus is mainly configured by a high voltage system 10 to which a high voltage is applied, an insulation resistance sensor 30 that detects an insulation resistance between the high voltage system 10 and a ground potential, and a control unit 40. Yes.

  The high voltage system 10 includes a drive motor 11 that applies driving force to the wheels of the vehicle, a fuel cell 12 that generates electric power, a power generated from the fuel cell 12, and a power that is discharged and supplied to the drive motor 11. Secondary battery 13 and a high voltage path 14 that electrically connects these high voltage auxiliary machines. The high voltage system 10 including the drive motor 11, the fuel cell 12, the secondary battery 13, and the high voltage path 14 is electrically insulated from the vehicle body (ground) by an insulation resistance.

  The high voltage system 10 is provided with relays 15 to 17 that can cut off the connection between the drive motor 11 and the secondary battery 13 via the high voltage path 14 according to the open / closed state of the high voltage system 10. The positive main relay 15 is provided on the positive electrode side of the secondary battery 13 in the high voltage path 14, and the negative main relay 17 is provided on the negative electrode side of the secondary battery 13. Further, the high voltage system 10 is provided with a system charging relay 16 in parallel with the plus-side main relay 15. Further, a fuel cell cutoff relay 18 is provided between the high voltage path 14 and the fuel cell 12, which can cut off the connection between the high voltage path 14 and the fuel cell 12 in accordance with the opening and closing of the self. . The open / close states of the plus side main relay 15, the system charging relay 16, the minus side main relay 17 and the fuel cell cutoff relay 18 are controlled by a control unit 40 which will be described later.

  FIG. 2 is a block diagram showing the insulation resistance sensor 30. The insulation resistance sensor 30 is a coupling capacitor type sensor that detects an insulation resistance between the high voltage system 10 and a ground potential (a potential of the vehicle body (ground)). The insulation resistance sensor 30 includes a rectangular wave generation means 31, a detection resistor 32, a coupling capacitor 33, a fluctuation detection means 34, and an insulation resistance calculation means 35.

  The rectangular wave generating means 31 generates a rectangular wave signal (pulse signal) having a predetermined frequency with a duty ratio of 50%, and outputs this to the high voltage path 14 via the detection resistor 32 and the coupling capacitor 33 (this book). In the embodiment, it is output to the secondary battery 13 side via the relays 15 to 17 on the high voltage path 14). Since the high voltage system 10 is insulated from the ground via the insulation resistance, the rectangular wave signal is output to the high voltage path 14 via the detection resistor 32 and the coupling capacitor 33. And output to the insulation resistance. Here, as the rectangular wave generating means 31, for example, a transmission circuit can be used. The detection resistor 32 and the coupling capacitor 33 are connected in series with each other, and are arranged in the order of the detection resistor 32 and the coupling capacitor 33 from the rectangular wave generating means 31 to the high voltage path 14.

  As the fluctuation detection means 34 and the insulation resistance calculation means 35, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an input / output interface can be used. However, the fluctuation detecting means 34 and the insulation resistance calculating means 35 may realize these functions by using an arithmetic circuit as well as realizing these functions described later by arithmetic processing of a microcomputer.

  The fluctuation detecting means 34 detects the voltage at the connection point P between the detection resistor 32 and the coupling capacitor 33, and detects the fluctuation of the detected voltage. Specifically, the fluctuation detecting means 34 has a timing (hereinafter referred to as “the peak voltage on the higher side” in the transition of the voltage at the connection point P corresponding to a predetermined sampling period (in this embodiment, the transmission period of the rectangular wave pulse). And a timing at which a lower peak voltage is reached (hereinafter referred to as a “lower peak timing”). Here, the peak voltage on the higher side is a voltage at the connection point P corresponding to the maximum voltage (the higher voltage level side) of the rectangular wave signal corresponding to one cycle, and the peak voltage on the lower side is a rectangle corresponding to one cycle. This is the voltage at the connection point P corresponding to the minimum voltage (low voltage level side) of the wave signal. The detected higher-order peak timing and lower-order peak timing are output to the insulation resistance calculating means 35.

  The insulation resistance calculation means 35 is a voltage at the connection point P between the detection resistor 32 and the coupling capacitor 33 at the high-order peak timing and low-order peak timing detected by the fluctuation detection means 34 (that is, the high-order and low-order positions). The insulation resistance is calculated based on the peak voltage on the side. The amplitude of the voltage fluctuation at the connection point P, that is, the difference between the high-side peak voltage and the low-side peak voltage is correlated with the insulation resistance. In general, the insulation resistance increases as the amplitude increases. By checking this characteristic in advance, the insulation resistance calculation means 35 calculates the insulation resistance RV from the peak voltages on the high and low sides. The calculated insulation resistance RV is output to the control unit 40.

  The control unit 40 can use a macro computer mainly composed of a CPU, a ROM, a RAM, and an input / output interface. The control unit 40 performs various arithmetic processes related to the driving state of the vehicle according to the control program stored in the ROM.

  In relation to the present embodiment, the control unit 40 includes a failure diagnosis unit 41. The failure diagnosis unit 41 is a relay that can cut off the connection between the drive motor 11 and the secondary battery 13 via the high voltage path 14, that is, the plus side main relay 15, the system charging relay 16, and the minus side main relay. 17 is a diagnosis target (hereinafter, these relays are collectively referred to as a “diagnosis target relay”), and the diagnosis target relays 15 to 17 in the high-voltage system 10 fail based on the insulation resistance detected by the insulation resistance sensor 30. Make a diagnosis. In order to perform such a failure diagnosis, the detection signal RV from the insulation resistance sensor 30 and the detection signal from the voltage sensor 22 that detects the voltage of the high voltage system 10 as the system voltage are input to the control unit 40. ing.

  The failure diagnosis unit 41 has the following three functions. First, the failure diagnosis unit 41 closes the insulation resistance detected by the insulation resistance sensor 30 and the fuel cell cutoff relay 18 from the open state to the closed state in the state in which the diagnosis target relays 15 to 17 are instructed to be closed. On the basis of the difference from the insulation resistance detected by the insulation resistance sensor 30 when the switch is switched to, a diagnosis is made of the closed adherence of the diagnostic relays 15 to 17 (closed adherence diagnosis). Here, the closed adhering is a state in which the relay is adhering while it is closed (on) due to attachment or the like.

  Secondly, the failure diagnosis unit 41 opens the insulation resistance detected by the insulation resistance sensor 30 in the state in which the diagnosis target relays 15 to 17 are instructed to be closed, and the diagnosis target relays 15 to 17. Based on the difference with the insulation resistance detected by the insulation resistance sensor 30 in the instructed state, the diagnosis target relays 15 to 17 are diagnosed for open fixation (open fixation diagnosis). Here, the open fixation is a state in which the relay is fixed while it is open (off).

  Third, the failure diagnosis unit 41 diagnoses that the diagnosis target relays 15 to 17 are not closed and fixed in the closed fixation diagnosis, and diagnoses that the diagnosis target relays 15 to 17 are not open and fixed in the open fixation diagnosis. It is determined that the diagnosis target relays 15 to 17 are not malfunctioning on the condition.

  In the present embodiment, the fuel cell 12 and the fuel cell cutoff relay 18 are connected to the side facing the insulation resistance sensor 30 via the relays 15 to 17 described above in the high voltage path 14. In this case, the fuel cell 12 and the fuel cell cutoff relay 18 change the capacitance or insulation resistance between the high voltage system and the ground potential by switching the open / close state of the fuel cell cutoff relay 18. Function as.

  FIG. 3 is a flowchart showing a procedure of failure diagnosis processing according to the present embodiment. The process shown in this flowchart is called at predetermined intervals and executed by the control unit 40. First, in step 1 (S1), it is determined whether or not a diagnosis condition, that is, a condition for executing diagnosis is satisfied. In the present embodiment, the diagnosis target relays 15 to 17 are diagnosed before the drive motor 11 connected to the secondary battery 13 by the diagnosis target relays 15 to 17 starts operating. Therefore, on the assumption that the drive motor 11 starts to operate, for example, on the assumption that the power is supplied to the drive motor 11 when the vehicle is started, this diagnosis condition is satisfied. The condition is not met. If an affirmative determination is made in step 1, that is, if the diagnosis condition is satisfied, the process proceeds to step 2 (S2). On the other hand, if a negative determination is made in step 1, that is, if the diagnosis condition is not satisfied, the processing after step 2 is skipped and the routine is exited.

  FIG. 4 is a flowchart showing the processing procedure of the closed adhering diagnosis in step 2. First, in step 10 (S10), the diagnosis target relays 15 to 17 and the fuel cell cutoff relay 18 are turned off. That is, the failure diagnosis unit 41 instructs the diagnosis target relays 15 to 17 and the fuel cell cutoff relay 18 to be in the open state. In step 11 (S11), the insulation resistance RV11 is acquired from the insulation resistance sensor 30 after a predetermined time t1 has elapsed from the timing when the closed state is instructed to the relays 15 to 18 in step 10. The acquired insulation resistance RV11 is stored in a memory (RAM). Here, the time t1 is set in advance by examining the reaction speed of the insulation resistance sensor 30 in advance through experiments and simulations and stabilizing the sensor response. Note that the capacitor coupling type sensor, such as the insulation resistance sensor 30 of this embodiment, has a fast response, and the response stabilizes in about several hundreds msec. Therefore, the time t1 is, for example, between 500 msec and 1 sec. Can be set.

  In step 12 (S12), the fuel cell cutoff relay 18 is turned on. That is, the failure diagnosis unit 41 instructs the fuel cell cutoff relay 18 to be closed. In step 13 (S 13), the insulation resistance RV 12 after the elapse of a predetermined time t 1 from the timing when the open state is instructed to the fuel cell cutoff relay 18 in step 12 is acquired from the insulation resistance sensor 30. The acquired insulation resistance RV12 is stored in a memory (RAM).

  In step 14 (S14), the insulation resistances RV11 and RV12 are compared, and it is determined whether or not the difference (absolute value) between them is greater than the first resistance determination value DRV1. Here, when there is a difference larger than the first resistance determination value DRV1 between the insulation resistances RV11 and RV12 acquired in the previous steps 11 and 13, any one of the relays to be diagnosed 15 to 17 is used. Is diagnosed as closed (welded). This is because if none of the diagnosis target relays 15 to 17 is closed and fixed, even if the state downstream of the diagnosis target relays 15 to 17 (that is, the side farther from the insulation resistance sensor 30) changes, This is because the output of the insulation resistance sensor 30 does not change. Specifically, when the downstream state changes, that is, when the fuel cell cutoff relay 18 is switched from the open state to the closed state, the stray capacitance between the high voltage system 10 and the ground potential changes. For this reason, if any of the diagnostic relays 15 to 17 is closed and stuck, the insulation resistance sensor 30 detects the change. That is, if the diagnosis target relays 15 to 17 are in the open state (off) according to the opening instruction of the failure diagnosis unit 41, the insulation resistance sensor 30 cannot detect the change in the stray capacitance.

  If the output of the insulation resistance sensor 30 does not change when there is no closed fixation, the first resistance determination value DRV1 can be set to “0”. However, in consideration of slight changes in the value of the insulation resistance sensor 30 due to sensor output noise and sampling timing, the first resistance determination value DRV1 is set to any one of the diagnosis target relays 15 to 17. The difference between the insulation resistances RV11 and RV12 that can be regarded as the occurrence of closed adhesion is set through experiments and simulations. Here, the sampling by the insulation resistance sensor 30 can set the first resistance determination value DRV1 to a small value by taking an average between several milliseconds to several seconds, thereby improving the diagnostic performance of closed adhesion. Can be planned. That is, the first resistance determination value DRV1 may be determined from the viewpoint of achieving both reduction in the time required for detection and improvement in diagnostic performance.

  If a negative determination is made in step 14, that is, if the difference between the insulation resistances RV11 and RV12 is equal to or less than the first resistance determination value DRV1 (| RV11−RV12 | ≦ DRV1), the process proceeds to step 15 (S15). On the other hand, if an affirmative determination is made in step 14, that is, if the difference between the insulation resistances RV11 and RV12 is greater than the first resistance determination value DRV1 (| RV11−RV12 |> DRV1), the process proceeds to step 16 (S16). move on.

  In step 15, a flag indicating that the diagnosis target relays 15 to 17 are not closed and stuck is set at a predetermined address in the backup ROM of the control unit 40 (diagnosis result: OK), and the routine is exited. On the other hand, in step 16, a flag indicating that closed fixation has occurred in any one of the diagnosis target relays 15 to 17 is set at a predetermined address in the backup ROM of the control unit 40 (diagnosis result: NG). . Then, in step 17 following step 16, after performing closed adhering spot detection processing for detecting a closed adhering place (diagnostic relays 15 to 17), the routine is exited.

  FIG. 5 is a flowchart showing a processing procedure for detecting the closed adhering portion in step 17. First, in step 20 (S20), it is determined whether or not the start-up preparation of the high voltage system 10 has been completed. In this embodiment, as will be described later, the closed charging location is detected by instructing the system charging relay 16 to be in the closed state. At this time, if the minus side main relay 17 is closed and fixed, electric power is supplied to the high voltage path 14 with the system charging relay 16 turned on, and the high voltage system 10 is started. Therefore, it is determined in advance whether or not the start-up preparation is completed so that there is no problem even if the high-voltage system 10 is started. Here, preparation for starting up the high-voltage system 10 is system diagnosis, and specifically includes diagnosis of CAN communication of the drive motor 11, diagnosis of an emergency stop line of the drive motor 11, and the like.

  If an affirmative determination is made in step 20, that is, if preparation for starting the high voltage system 10 is completed, the process proceeds to step 21 (S21). On the other hand, if a negative determination is made in step 20, that is, if the preparation for starting the high voltage system is not completed, the process returns to step 20, and the same determination is made after a predetermined time.

  In step 21, the diagnostic object relays 15 to 17 and the fuel cell cutoff relay 18 are turned off. That is, the failure diagnosis unit 41 instructs the diagnosis target relays 15 to 17 and the fuel cell cutoff relay 18 to be in the open state. In step 22 (S22), the system charging relay 16 is turned on. That is, the failure diagnosis unit 41 instructs the system charging relay 16 to be closed. In step 23 (S23), the system voltage VD1 is acquired from the voltage sensor 22.

  In step 24 (S24), it is determined whether or not system voltage VD1 is larger than voltage determination value DVD1. When the minus side main relay 17 is closed and fixed, power is supplied to the high voltage path 14 by instructing the system charging relay 16 to be in the closed state. By setting to an appropriate value through simulation, it can be determined whether or not the minus side main relay 17 is closed and fixed. If the determination in step 24 is affirmative, that is, if the system voltage VD1 is greater than the voltage determination value DVD1 (VD1> DVD1), the process proceeds to step 25 (S25). On the other hand, if a negative determination is made in step 24, that is, if the system voltage VD1 is equal to or lower than the voltage determination value DVD1 (VD1 ≦ DVD1), the process proceeds to step 26.

  In step 25, a flag indicating that the minus side main relay 17 is closed and fixed is set at a predetermined address in the backup ROM of the control unit 40, and the routine is exited. On the other hand, in step 26, a flag indicating that the plus-side relay, that is, the plus-side main relay 15 or the system charging relay 16 is closed and stuck is set at a predetermined address in the backup ROM of the control unit 40. Exit the routine.

  Referring to FIG. 3 again, in step 3 (S3), open adhesion diagnosis is executed. FIG. 6 is a flowchart showing the procedure of the open adhesion diagnosis in step 3. In step 30 (S30), the diagnostic object relays 15 to 17 and the fuel cell cutoff relay 18 are turned off. That is, the failure diagnosis unit 41 instructs the diagnosis target relays 15 to 17 and the fuel cell cutoff relay 18 to be in the open state. In step 31 (S31), the insulation resistance RV21 is acquired from the insulation resistance sensor 30 after a predetermined time t1 has elapsed from the timing at which the relays 15 to 18 are instructed to be opened in step 30. The acquired insulation resistance RV21 is stored in a memory (RAM).

  In step 32 (S32), the system charging relay 16 is turned on. That is, the failure diagnosis unit 41 instructs the system charging relay 16 to be closed. In step 33 (S33), the insulation resistance RV22 after the predetermined time t1 has elapsed from the timing when the closed state is instructed to the system charging relay 16 in step 32 is obtained from the insulation resistance sensor 30. The acquired insulation resistance RV22 is stored in a memory (RAM).

  In step 34 (S34), the insulation resistances RV21 and RV22 are compared, and it is determined whether or not the difference (absolute value) between them is greater than the second resistance determination value DRV2. Here, when there is a difference larger than the second resistance determination value DRV2 between the insulation resistances RV21 and RV22 acquired in the previous steps 31 and 33, the insulation resistance or stray capacitance of the high voltage system 10 is This means that the system charging relay 16 is normally closed (ON). The second resistance determination value DRV2 can be determined from the same viewpoint as the first resistance determination value DRV1 shown in the above-described closed adhesion diagnosis process.

  If an affirmative determination is made in step 34, that is, if the difference (absolute value) between the insulation resistances RV21 and RV22 is greater than the second resistance determination value DRV2 (| RV21−RV22 |> DRV2), step 35 (S35) ) On the other hand, if a negative determination is made in step 34, that is, if the difference (absolute value) between the insulation resistances RV21 and RV22 is equal to or smaller than the second resistance determination value DRV2 (RV21−RV22 | ≦ DRV2), step 48 described later. Proceed to

  In step 35, a flag indicating that the system charging relay 16 is not open and fixed is set at a predetermined address of the backup ROM of the control unit 40 (diagnosis result of the system charging relay 16: OK).

  In step 36 (S36), the diagnostic object relays 15 to 17 and the fuel cell cutoff relay 18 are turned off. That is, the failure diagnosis unit 41 instructs the diagnosis target relays 15 to 17 and the fuel cell cutoff relay 18 to be in the open state. In step 37 (S37), the insulation resistance RV31 is acquired from the insulation resistance sensor 30 after a predetermined time t1 has elapsed from the timing at which the relays 15-18 are instructed to be opened in step 10. The acquired insulation resistance RV31 is stored in a memory (RAM).

  In step 38 (S38), the plus side main relay 15 is turned on. That is, the failure diagnosis unit 41 instructs the plus main relay 15 to be closed. In step 39 (S39), the insulation resistance RV32 is acquired from the insulation resistance sensor 30 after the elapse of a predetermined time t1 from the timing when the open state is instructed to the plus main relay 15 in step 38. The acquired insulation resistance RV32 is stored in a memory (RAM).

  In step 40 (S40), the insulation resistances RV31 and RV32 are compared, and it is determined whether or not the difference (absolute value) between them is greater than the third resistance determination value DRV3. Here, when there is a difference larger than the third resistance determination value DRV3 between the insulation resistances RV31 and RV32 acquired in the previous steps 37 and 39, the insulation resistance or stray capacitance of the high voltage system 10 is This means that it has changed, and it is determined that the plus-side main relay 15 is normally closed. The third resistance determination value DRV3 can be determined from the same viewpoint as the first resistance determination value DRV1 shown in the above-described closed adhesion diagnosis process.

  If an affirmative determination is made in step 40, that is, if the difference (absolute value) between the insulation resistances RV31 and RV32 is greater than the third resistance determination value DRV3 (| RV31−RV32 |> DRV3), step 41 (S41) ) On the other hand, if a negative determination is made in step 40, that is, if the difference (absolute value) between the insulation resistances RV31 and RV32 is equal to or smaller than the third resistance determination value DRV3 (RV31−RV32 | ≦ DRV3), step 48 described later. Proceed to

  In step 41, a flag indicating that the plus-side main relay 15 is not fixed open is set at a predetermined address in the backup ROM of the control unit 40 (diagnosis result of the plus-side main relay 15: OK).

  In step 42 (S42), the diagnostic object relays 15 to 17 and the fuel cell cutoff relay 18 are turned off. That is, the failure diagnosis unit 41 instructs the diagnosis target relays 15 to 17 and the fuel cell cutoff relay 18 to be in the open state. In step 43 (S43), the insulation resistance RV41 is acquired from the insulation resistance sensor 30 after a predetermined time t1 has elapsed from the timing at which the relays 15 to 18 are instructed to be opened in step 10. The acquired insulation resistance RV41 is stored in a memory (RAM).

  In step 44 (S44), the minus side main relay 17 is turned on. That is, the failure diagnosis unit 41 instructs the minus main relay 17 to be closed. In step 45 (S45), the insulation resistance RV42 is acquired from the insulation resistance sensor 30 after a predetermined time t1 has elapsed from the timing when the minus main relay 17 is instructed to be closed in step 44. The acquired insulation resistance RV42 is stored in a memory (RAM).

  In step 46 (S46), the insulation resistances RV41 and RV42 are compared, and it is determined whether or not the difference (absolute value) between them is larger than the fourth resistance determination value DRV4. Here, if there is a difference larger than the fourth resistance determination value DRV4 between the insulation resistances RV41 and RV42 acquired in the previous steps 43 and 45, the insulation resistance or stray capacitance of the high voltage system 10 is This means that the negative main relay 17 is normally closed. The fourth resistance determination value DRV4 can be determined from the same viewpoint as the first resistance determination value DRV1 shown in the above-described closed adhesion diagnosis process.

  If an affirmative determination is made in step 46, that is, if the difference (absolute value) between the insulation resistances RV41 and RV42 is greater than the fourth resistance determination value DRV4 (| RV41−RV42 |> DRV4), step 47 (S47) ) On the other hand, when a negative determination is made in step 46, that is, when the difference (absolute value) between the insulation resistances RV41 and RV42 is equal to or smaller than the fourth resistance determination value DRV4 (RV41−RV42 | ≦ DRV4), step 48 described later. Proceed to

  In step 47, a flag indicating that the minus side main relay 17 is not fixed open is set at a predetermined address in the backup ROM of the control unit 40 (diagnosis result of the minus side main relay 17: OK), and this routine is exited. . On the other hand, in step 48, a flag indicating that the diagnostic object relays 15 to 17 are open and fixed is set at a predetermined address in the backup ROM of the control unit 40 (diagnosis result: NG), and the routine is exited. .

  FIG. 7 shows a timing chart in the closed adhesion diagnosis. As shown in the figure, when the fuel cell cutoff relay 18 is turned on (ON), the output (insulation resistance) RV of the insulation resistance sensor 30 does not change unless the diagnosis target relays 15 to 17 are closed and fixed. However, when any one of the diagnosis target relays 15 to 17 is closed and stuck (failed), its output RV changes. Therefore, it is possible to diagnose the closed adherence of the diagnosis target relays 15 to 17 from this output change. FIG. 8 is a timing chart in the open adhesion diagnosis. As shown in the figure, when each of the relays 15 to 17 to be diagnosed is turned on one by one, the insulation resistance or stray capacitance of the high voltage system 10 changes as the relay is turned on. The output of 30 varies. Therefore, when there is no such output change, it is possible to diagnose whether the diagnostic relays 15 to 17 are stuck open. By such a series of processes, the failure diagnosis unit 41 comprehensively determines that no failure has occurred in the relays 15 to 17 on the condition that the relays 15 to 17 to be diagnosed are not closed and open. Make a decision.

  Such a series of failure diagnosis processing is executed before the high voltage system 10 is started with the start of the fuel cell vehicle or after the high voltage system 10 is stopped with the stop of the fuel cell vehicle.

  FIG. 9 is a flowchart showing the startup procedure of the fuel cell vehicle. The process shown in this flowchart is executed by the control unit 40. First, in step 50, the control unit 40 determines whether or not the start switch of the fuel cell vehicle is turned on. If an affirmative determination is made in step 50, that is, if the start switch is turned on, the routine proceeds to step 51. On the other hand, if a negative determination is made in step 50, that is, if the start switch is not turned on, the process returns to step 50 after a predetermined time, and the same determination is performed again.

  In step 51, the control unit 40 (particularly, the failure diagnosis unit 41) performs the series of failure diagnosis processes described above. Then, on the condition that the diagnosis target relays 15 to 17 are not closed and open, the failure diagnosis unit 41 performs a comprehensive determination that no failure has occurred in these relays 15 to 17. In step 52, the high voltage system 10 is turned on, thereby starting the high voltage system. In step 54, processing associated with the travel of the fuel cell vehicle is performed. In step 51, if a failure has occurred in the diagnosis target relays 15 to 17, it is preferable to skip the subsequent processing and stop the activation.

  FIG. 10 is a flowchart showing a stop procedure of the fuel cell vehicle. The process shown in this flowchart is executed by the control unit 40. First, in step 60, the control unit 40 determines whether or not the start switch of the fuel cell vehicle is turned off. If an affirmative determination is made in step 60, that is, if the start switch is turned off, the routine proceeds to step 61. On the other hand, if a negative determination is made in step 60, that is, if the start switch is not turned off, the process returns to step 60 after a predetermined time, and the same determination is performed again.

  In step 61, the high voltage system 10 is turned off, thereby stopping the high voltage system 10. In step 62, the control unit 40 (particularly, the failure diagnosis unit 41) performs the series of failure diagnosis processes described above. In consideration of the fact that the high-voltage system 10 has just been turned on, it is not necessary to perform the open fixation diagnosis, but it may be performed depending on the characteristics of the system. In the closed fixation diagnosis, as shown in the timing chart of FIG. 11, the output (insulation resistance) of the insulation resistance sensor 30 stored in the ON state of the high voltage system 10, the plus side main relay 15, and the minus side The output value after the main relay 17 is turned off is compared, and if there is no difference between the two, it may be determined that one of the relays 15 and 17 is closed and fixed. In step 54, the fuel cell vehicle is stopped.

  Thus, according to the present embodiment, the relay failure diagnosis apparatus includes the high voltage system 10, the diagnosis target relay (first relay), the insulation resistance sensor 30, the state change unit 21, and the failure diagnosis unit 41. Have Here, the high voltage system 10 includes at least a load (in the present embodiment, the drive motor 11), the secondary battery 13, and a high voltage path 14 that electrically connects the drive motor 11 and the secondary battery 13. Including. The relay to be diagnosed can cut off the connection between the drive motor 11 and the secondary battery 13 via the high voltage path 14 according to its own open / closed state. The insulation resistance sensor 30 is connected to the high voltage path 14 and is a coupling capacitor type sensor that detects an insulation resistance between the high voltage system 10 and the ground potential. The state change unit 21 is connected to the side opposite to the insulation resistance sensor 30 via the diagnosis target relay in the high voltage path 14, and the capacitance or insulation resistance between the high voltage system 10 and the ground potential is set. Change. The failure diagnosis unit 41 performs failure diagnosis of the diagnosis target relay.

  The failure diagnosis unit 41 includes a closed adhesion diagnosis unit, an open adhesion diagnosis unit, and a determination unit when this is functionally grasped. In this case, the closed fixing diagnostic means changes the insulation resistance detected by the insulation resistance sensor 30 and the capacitance or the insulation resistance by the state changing unit 21 in a state in which the diagnosis target relay is instructed to open. In this case, based on the difference from the insulation resistance detected by the insulation resistance sensor 30, the closure of the diagnosis target relay is diagnosed. The open adhesion diagnostic means is detected by the insulation resistance sensor 30 when the diagnosis target relay is instructed to be in the open state and detected by the insulation resistance sensor 30 when the diagnosis target relay is instructed to be in the closed state. Based on the difference from the insulation resistance, the open adhesion of the diagnosis target relay is diagnosed. The determination means is a diagnosis object relay on condition that the diagnosis object relay is diagnosed as not being closed and fixed by the closed adhesion diagnosis means, and the diagnosis object relay is diagnosed as not being open and adhered by the open adhesion diagnosis means. Is determined not to have failed. The individual functions executed by the closed adhesion diagnostic means, the open adhesion diagnostic means, and the determination means are executed by the failure diagnosis unit 41 in the present embodiment.

  According to this configuration, the diagnosis of the relay to be diagnosed is diagnosed as being closed and the diagnosis target relay is assured to be open, and it is diagnosed that the diagnosis object relay is not closed and stuck, and has been diagnosed as not being open and stuck. As a result, it is determined that the diagnosis target relay has not failed. This makes it possible to perform a diagnosis that comprehensively evaluates both the closed and open fixations, thereby improving the accuracy of failure diagnosis.

  Further, in the diagnosis of the closed adhesion, when diagnosing the closed adhesion of the relay to be diagnosed, the state change unit 21 is operated, and the relative comparison of the outputs of the insulation resistance sensor 30 (that is, whether there is a difference between the outputs) Whether or not it is closed is diagnosed. Therefore, even when the impedance of the vehicle and the insulation resistance change over time, it is possible to accurately diagnose the open fixation. In addition, according to the closed sticking diagnosis, it is possible to suppress a situation in which the high voltage system 10 is inadvertently turned on (power supply). Further, in the diagnosis of open fixation, the diagnosis of open fixation is made by relative comparison of the outputs of the insulation resistance sensor 30 when the opening / closing state of the relay to be diagnosed is switched (that is, whether there is a difference between the outputs). Done. Therefore, even when the impedance of the vehicle and the insulation resistance change over time, it is possible to accurately diagnose the open fixation.

  In addition, according to the present embodiment, the relay to be diagnosed includes the positive main relay 15 provided on the positive electrode side of the secondary battery 13 and the negative electrode provided on the negative electrode side of the secondary battery 13 in the high voltage path 14. Side main relay 17 and system charging relay 16 connected in parallel to plus side main relay 15. Here, the failure diagnosis unit 41, which is an open sticking diagnosis means, diagnoses the open sticking related to the plus main relay 15, the minus main relay 17, and the system charging relay 16, which are diagnosis target relays. The diagnosis is performed from the system charging relay 16 in preference to the relay 15 and the minus side main relay 17.

  In the open adhesion diagnosis, the insulation resistance is acquired in a state in which the diagnosis target relays 15 to 17 are instructed to be closed. That is, when the relay to be diagnosed is turned on, if the relay connected to the pole on the opposite side is welded to the pole connected to the relay to be turned on, the high voltage system is turned on. In this regard, according to the present embodiment, since the system charging relay 16 is first turned on by diagnosing open fixation from the system charging relay 16, even if the minus side main relay 17 is closed and fixed, The instantaneous current accompanying energization can be suppressed. Moreover, when the plus side main relay 15 is closed and fixed, the high voltage system is not turned on, and the system failure accompanying the failure diagnosis can be suppressed.

  In this embodiment, the relay failure diagnosis apparatus further includes a voltage sensor 22 that detects the voltage of the high voltage system 10 as a system voltage. In this case, the failure diagnosis unit 41 instructs the system charging relay 16 to be in a closed state when it is diagnosed that the diagnosis target relay is closed and fixed in the closed and fixed diagnosis. Then, based on the system voltage detected by the voltage sensor 22, the failure diagnosis unit 41 determines whether at least one of the plus side main relay 15 and the system charging relay 16 is closed and fixed, or the minus side main relay 17 is closed. It further has welding location detection means for detecting whether it is fixed. According to this configuration, it is possible to specify the location of the relay that is closed and fixed. Thereby, the failure location can be easily identified by referring to the diagnosis result.

  In addition, prior to the start of load operation, the failure diagnosis unit 41 performs failure diagnosis on a diagnosis target relay that can disconnect the connection between the load and the secondary battery 13. Here, in this embodiment, the drive motor 11 is illustrated as a load, and the diagnosis target relay that can cut off the connection state between the drive motor 11 and the secondary battery 13 prior to the start of the operation of the drive motor 11. Failure diagnosis is performed for 15-17. In the present embodiment, only the drive motor 11 is used as a load. However, other fuel cell vehicles include a fuel cell air supply compressor, a fuel cell fuel circulation pump, an air conditioner compressor, and the like. It is connected to the path 14. That is, when relays are provided corresponding to these loads, failure diagnosis can be executed for these relays. At this time, if it is attempted to perform a fault diagnosis for these relays through a series of operations, the processing time increases. However, since there are few scenes in which each load starts to operate simultaneously, failure diagnosis can be performed in parallel with the processing operation of the entire system by performing failure diagnosis prior to the start of each load operation. Therefore, it is possible to suppress the occurrence of inconvenience that the diagnosis time becomes redundant.

  In the present embodiment, the failure diagnosis unit 41 performs failure diagnosis before starting the high voltage system 10 or after stopping the high voltage system 10. According to such a configuration, failure diagnosis is performed when the system is started or stopped, so that the diagnosis frequency can be increased. Thereby, the failure detection performance of the diagnosis target relay can be improved.

  In the present embodiment, the failure diagnosis unit 41 performs diagnosis (open adhesion diagnosis) by the open adhesion diagnosis means after performing diagnosis (closed adhesion diagnosis) by the closed adhesion diagnosis means. Assuming that any one of the relays is welded, the high voltage system may be inadvertently turned on when the relay is turned on / off in performing the fault diagnosis. However, after diagnosing closed adhesion and finding that it is not closed, the high voltage system is turned on even if the relay is turned on only on the positive side or the negative side for fault diagnosis. Never become. This suppresses the possibility that the high voltage system is inadvertently turned on.

  Further, in the present embodiment, the state changing unit 21 can cut off the connection between the fuel cell 12 connected to the high voltage path 14 and the fuel cell 12 and the high voltage path 14 according to its own open / closed state. The fuel cell cutoff relay 18 is provided, and the capacitance or insulation resistance between the high voltage system 10 and the ground potential is changed by switching the open / close state of the fuel cell cutoff relay 18. According to this configuration, in a fuel cell vehicle, diagnosis can be performed using the fuel cell cutoff relay 18 that is normally equipped. Therefore, it is possible to diagnose the closed adhering of the diagnosis target relay without increasing the cost.

  In the present embodiment, the capacitance or the insulation resistance of the high voltage system 10 is changed by switching the open / close state of the fuel cell cutoff relay 18, but the present invention is not limited to this. For example, the state change unit 21 can cut off the connection between the resistor 19 or the capacitor 20 connected to the high voltage path 14 and the resistor 19 or the capacitor 20 and the high voltage path 14 according to its open / closed state. A change relay (fuel cell cutoff relay) 18 may be provided. In this case, by switching the open / close state of the change relay 18, the insulation resistance or capacitance between the high voltage system 10 and the ground potential can be reduced. Change. According to such a configuration, the failure diagnosis of the diagnosis object relay can be performed only by adding the resistor 19 or the capacitor 20 and the change relay 18.

1 is a configuration diagram of a fuel cell vehicle to which a relay failure diagnosis apparatus according to an embodiment is applied. Block diagram showing insulation resistance sensor 30 The flowchart which shows the procedure of the failure diagnosis processing concerning this embodiment The flowchart which shows the process sequence of the closed sticking diagnosis in step 2 The flowchart which shows the process sequence of the closed adhering location detection in step 17 The flowchart which shows the process sequence of the open adhesion diagnosis in step 3 Timing chart for closed fixation diagnosis Timing chart for open adhesion diagnosis Flow chart showing start-up procedure of fuel cell vehicle Flow chart showing stop procedure of fuel cell vehicle Timing chart for closed adhesion diagnosis at stop

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 High voltage system 11 Drive motor 12 Fuel cell 13 Secondary battery 14 High voltage path 15 Positive side main relay 16 System charge relay 17 Negative side main relay 18 Fuel cell cutoff relay 19 Resistance 20 Capacitor 21 State change part 22 Voltage sensor 30 Insulation Resistance sensor 31 Rectangular wave generation means 32 Detection resistance 33 Coupling capacitor 34 Fluctuation detection means 35 Insulation resistance calculation means 40 Control unit 41 Fault diagnosis unit

Claims (9)

In the relay fault diagnosis device,
A high voltage system including at least a load, a secondary battery, and a high voltage path electrically connecting the load and the secondary battery;
A first relay capable of cutting off a connection between the load and the secondary battery via the high-voltage path according to its open / closed state;
A coupling capacitor type insulation resistance sensor connected to the high voltage path for detecting an insulation resistance between the high voltage system and a ground potential;
In the high-voltage path, a state change that is connected to the side facing the insulation resistance sensor via the first relay and changes a capacitance or an insulation resistance between the high-voltage system and a ground potential. And
A failure diagnosis unit that performs failure diagnosis of the first relay;
The failure diagnosis unit
In the state in which the open state is instructed to the first relay, the insulation resistance sensor detects when the insulation resistance detected by the insulation resistance sensor and the capacitance or the insulation resistance are changed by the state change unit. Closed adhesion diagnostic means for diagnosing the closed adhesion of the first relay based on a difference from the detected insulation resistance;
Insulation resistance detected by the insulation resistance sensor when the first relay is instructed to open, and detected by the insulation resistance sensor when the first relay is instructed to be closed An open adhesion diagnosis means for diagnosing the open adhesion of the first relay based on a difference with an insulation resistance;
On condition that the first relay is diagnosed as not being closed and fixed by the closed fixation diagnostic means, and the first relay is diagnosed as not being open and fixed by the open fixation diagnostic means, A relay failure diagnosis apparatus comprising: determination means for determining that the first relay has not failed. The first relay includes a positive main relay provided on the positive electrode side of the secondary battery, a negative main relay provided on the negative electrode side of the secondary battery, and the positive side in the high voltage path. A system charging relay connected in parallel to the main relay,
In the case of diagnosing open sticking related to the positive main relay, the negative main relay, and the system charging relay, which is the first relay, the open sticking diagnosis means is configured to detect the positive main relay and the negative side. The relay failure diagnosis apparatus according to claim 1, wherein diagnosis is performed from the system charging relay in preference to a main relay. A voltage sensor for detecting a voltage of the high voltage system as a system voltage;
The failure diagnosis unit instructs the system charging relay to be in a closed state and is detected by the voltage sensor when the closed adhesion diagnosis unit diagnoses that the first relay is closed and fixed. A welding location detecting means for detecting whether at least one of the plus side main relay and the system charging relay is closed and fixed, or whether the minus side main relay is closed and fixed, based on the system voltage The relay failure diagnosis apparatus according to claim 2, wherein   The failure diagnosis unit performs the failure diagnosis on the first relay that can cut off a connection between the load and the secondary battery prior to starting the operation of the load. The relay failure diagnosis device according to any one of Items 1 to 3.   5. The fault diagnosis unit according to claim 1, wherein the fault diagnosis unit performs the fault diagnosis before starting the high voltage system or after stopping the high voltage system. Relay failure diagnosis device.   The relay failure diagnosis apparatus according to claim 1, wherein the failure diagnosis unit performs diagnosis by the open adhesion diagnosis unit after performing diagnosis by the closed adhesion diagnosis unit. . The state change unit is
A fuel cell connected to the high voltage path;
A second relay capable of cutting off the connection between the fuel cell and the high voltage path according to its open / closed state;
7. The capacitance or insulation resistance between the high voltage system and a ground potential is changed by switching an open / close state of the second relay. 8. Relay failure diagnosis device. The state change unit is
A capacitor connected to the high voltage path;
A second relay capable of interrupting a connection between the capacitor and the high voltage path according to a switching state of the self;
The relay according to any one of claims 1 to 6, wherein a capacitance between the high voltage system and a ground potential is changed by switching an open / close state of the second relay. Fault diagnosis device. The state change unit is
A resistor connected to the high voltage path;
A second relay capable of cutting off the connection between the resistor and the high-voltage path according to its open / closed state;
The relay failure according to any one of claims 1 to 6, wherein an insulation resistance between the high voltage system and a ground potential is changed by switching an open / close state of the second relay. Diagnostic device.

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