Sticking diagnosis method and sticking diagnosis device

Abstract

This sticking diagnosis method includes: a selection step of selecting, as a diagnostic relay, one relay among a plurality of negative electrode relays N1-Nn and a plurality of charging relays C1-Cn included in a plurality of battery pack circuits M1-Mn; a step of charging a capacitor C in a state where the one diagnostic relay is turned on for each start of a vehicle and the charging relays C1-Cn or the negative electrode relays N1-Nn paired with the one diagnostic relay are turned on; and a step of diagnosing off-fixing of the charging relays C1-Cn and the negative electrode relays N1-Nn according to the charged state of the capacitor C.

Description

Method and device for diagnosing sticking

[0001] The present invention relates to a method and an apparatus for diagnosing a stuck state.

[0002] Conventionally, there have been known power supply circuit control devices that determine whether a relay is welded. For example, in a power supply circuit control device described in Patent Document 1, the power supply circuit includes a first relay that controls electrical conduction / de-energization between a load and one pole of a power storage mechanism, a circuit having a resistor connected in series with the first relay, a second relay connected in parallel with the circuit, and a third relay that controls electrical conduction / de-energization between the load and the other pole of the power storage mechanism, and the control device distinguishes between a fixation on the energized side and a fixation on the non-energized side of the relay to determine an abnormality in the relay (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2006-081340

[0004] However, when the power supply circuit is configured with multiple parallel circuits in which multiple circuits each including a first relay, a second relay, a third relay, and a resistor are connected in parallel, there is a problem that the time required to diagnose a stuck relay increases.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for diagnosing a stuck relay, which can shorten the time required for diagnosing a stuck relay.

[0006] The present invention solves the above problem by selecting one of the multiple negative electrode relays and multiple charging relays included in each of the multiple battery pack circuits as a diagnostic relay, and each time the vehicle is started, charging a capacitor with one diagnostic relay turned on and the charging relay or negative electrode relay paired with the diagnostic relay turned on, and diagnosing whether the charging relay and negative electrode relay are stuck off depending on the charging state of the capacitor.

[0007] According to the present invention, the time required to diagnose a stuck relay can be reduced.

[0008] Fig. 1 is a block diagram of a vehicle power supply system according to an embodiment of the present invention. Fig. 2 is a flowchart showing steps of a method for diagnosing a stuck capacitor according to an embodiment of the present invention. Fig. 3 is a graph showing characteristics of a capacitor voltage during charging of the capacitor. Fig. 4 is a graph showing characteristics of a capacitor voltage during charging of the capacitor.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a block diagram of a vehicle power supply system according to an embodiment of the present invention.

[0010] The vehicle power supply system 1 according to this embodiment includes multiple battery pack circuits M1-Mn, an inverter 2, a capacitor 3, a voltage sensor 5, and a controller 10. The vehicle power supply system is installed in a vehicle and supplies power to a load installed in the vehicle. The multiple battery pack circuits M1-Mn are configured as multiple parallel circuits in which the battery pack circuits M1-Mn are connected in parallel. The multiple battery pack circuits M1-Mn are circuits that switch between supplying and cutting off power between a vehicle power source and the load. The multiple battery pack circuits M1-Mn correspond to the "battery pack parallel circuits" of the present invention, and the circuit including the multiple battery pack circuits M1-Mn and the capacitor 3 corresponds to the "power supply circuit" of the present invention. Furthermore, the device including the multiple battery pack circuits M1-Mn, the capacitor 3, and the controller 10 corresponds to the "sticking diagnosis device" of the present invention.

[0011] The battery pack circuit M1 includes a battery pack B1, a positive electrode relay P1, a negative electrode relay N1, a charging relay C1, and a charging resistor R1. The positive electrode relay P1, the negative electrode relay N1, and the charging relay C1 are relay switches with mechanical contacts, and are switched on and off under the control of the controller 10. Note that the positive electrode relay P1, the negative electrode relay N1, and the charging relay C1 may also be semiconductor switches. The battery pack B1 is a battery group in which multiple secondary batteries, such as lithium-ion batteries or lead batteries, are connected in parallel and / or series. The battery pack B1 corresponds to a vehicle power source. The battery pack B1 is electrically connected to the positive electrode relay P1 and other circuit elements included in the battery pack circuit M1, and to the capacitor 3.

[0012] In the battery pack circuit M1, a positive electrode relay P1 is connected in parallel to a series circuit connecting a charging relay C1 and a charging resistor R1 in series, and a battery pack B1 and a negative electrode relay N1 are connected to a parallel circuit connecting the series circuit of the charging relay C1 and the charging resistor R1 and the positive electrode relay P1 in parallel. The series circuit of the charging relay C1 and the charging resistor R1 is a pre-charge circuit that charges the capacitor 3. The charging resistor R1 limits the current value during capacitor charging. The charging relay C1 and the positive electrode relay P1 are connected in series with the positive electrode of the battery pack B1. The negative electrode relay N1 is connected in series with the negative electrode of the battery pack B1. The charging relay C1, the positive electrode relay P1, and the negative electrode relay are also electrically connected to the inverter 2. When charging the capacitor 3, the paired negative electrode relay N1 and charging relay C1 are turned on. After the capacitor 3 is charged, the negative and positive relays N1 and P1, which form a pair, are turned on when power from the battery pack B1 is supplied to the inverter 2. The current sensor S1 is connected to the battery pack B1 and detects the charge / discharge current of the battery pack B1.

[0013] The battery pack circuits M2 and Mn have the same circuit configuration as the battery pack circuit M1, and include battery packs B2 and Bn, positive electrode relays P1 and Pn, negative electrode relays N1 and Nn, charging relays C1 and Cn, and charging resistors R1 and Rn. n represents the number of battery pack circuits incorporated in the power supply circuit. As shown in Figure 1, the battery pack circuits M1, M2, and Mn are connected in parallel to a capacitor 3 and arranged in order from the first battery pack circuit M1 to the second battery pack circuit M2, and finally to the nth battery pack circuit Mn.

[0014] The connection lines (C, N lines) electrically connecting the charging relays C1 to Cn and the negative relays N1 to Nn in series are charging lines (charging circuits) for precharging. The connection lines (P, N lines) electrically connecting the positive relays P1 to Pn and the negative relays N1 to Nn in series are high-voltage lines (high-voltage circuits) for supplying current when the vehicle is running or the battery is being charged. In other words, the power supply circuit included in the vehicle power supply system includes n connection lines (C, N lines) and n connection lines (P, N lines).

[0015] The inverter 2 is an example of a load of the vehicle, includes a power conversion circuit, converts the power output from the assembled batteries B1 to Bn, and outputs it to the motor. During regenerative operation of the motor, the inverter 2 converts the power generated by the motor and outputs the converted power to the assembled batteries B1 to Bn.

[0016] A smoothing capacitor 3 is connected to the input side of the inverter 2 (the connection side of the assembled batteries B1 to Bn). The capacitor 3 is connected in parallel to a parallel battery circuit in which a plurality of assembled battery circuits M1 to Mn are connected in parallel. A voltage sensor 5 is a sensor that detects the voltage of the capacitor 3, and is connected in parallel to the capacitor 3. Note that while the capacitor 3 and the voltage sensor 5 are shown in FIG. 1 as components outside the inverter 2 circuit, the capacitor 3 and the voltage sensor 5 may be components inside the inverter 2 circuit or outside the inverter 2 circuit.

[0017] The controller 10 has functions such as switching the charging relays C1 to Cn, positive electrode relays P1 to Pn, and negative electrode relays N1 to Nn on and off, diagnosing whether the charging relays C1 to Cn, positive electrode relays P1 to Pn, and negative electrode relays N1 to Nn are stuck, and managing the state of the capacitor 3. The controller 10 has a processor for implementing the various functions, a memory that stores programs executed by the processor, and the like. The controller 10 acquires information about the current flowing through the battery pack circuits M1 to Mn from current sensors S1 to Sn, and acquires voltage information about the capacitor 3 from a voltage sensor 5. Note that the controller 10 is not limited to the function of switching the relays on and off, and may also have a function of managing the state of the battery packs B1 to Bn, for example.

[0018] In the following description, when referring to the charging relays C1 to Cn collectively, or when referring to a charging relay without specifying a relay among the charging relays C1 to Cn, the symbols for the charging relays C1 to Cn will be written as "C1 to Cn." For example, when referring to turning on the charging relays C1 to Cn, it is sufficient that at least one of the charging relays C1 to Cn is turned on. When referring to turning on one charging relay C1 to Cn, it is sufficient that one of the charging relays C1 to Cn is turned on. When referring to turning on all the charging relays C1 to Cn, it is sufficient that n charging relays C1 to Cn are turned on. The symbol notations for the negative and positive relays, "N1 to Nn" and "P1 to Pn," are the same as the symbol notations for the charging relays.

[0019] The relay fixation diagnosis function will now be described. The controller 10 diagnoses whether the charging relays C1 to Cn, the positive electrode relays P1 to Pn, and the negative electrode relays N1 to Nn are fixed on the basis of the currents detected by the current sensors S1 to Sn and / or the voltages detected by the voltage sensor 5. For example, the controller 10 charges the capacitor 3 with the charging relay C1 and the negative electrode relay N1 turned on and detects the capacitor voltage using the voltage sensor 5. If the detected voltage from the voltage sensor 5 does not increase, the controller 10 determines that at least one of the charging relay C1 and the negative electrode relay N1 is fixed off. The controller 10 may also diagnose whether the charging relay C1 and the negative electrode relay N1 are fixed off on the basis of the detected voltage from the current sensor S1. For example, if the current detected by the current sensor S1 is equal to or lower than a predetermined value, the controller 10 determines that at least one of the charging relay C1 and the negative electrode relay N1 is fixed off. Furthermore, the controller 10 can diagnose whether the charging relays C2 to Cn and the negative relays N2 to Nn are stuck off using the same diagnostic method as for the charging relay C1 and the negative relay N1 being stuck off.

[0020] The controller 10 may turn on all of the charging relays C1 to Cn and all of the negative relays N1 to Nn and diagnose whether the charging relays C1 to Cn and the negative relays N1 to Nn are stuck off based on the detected voltage of the capacitor 3 and the detected current of the current sensors S1 to Sn while the capacitor 3 is being charged. For example, if the detected voltage of the capacitor 3 increases while the current detected by the current sensor S2 is equal to or less than a predetermined value while the capacitor 3 is being charged, the controller 10 determines that at least one of the charging relay C2 and the negative relay N2 is stuck off. Note that the controller 10 does not necessarily need to turn on all of the charging relays C1 to Cn and all of the negative relays N1 to Nn when charging the capacitor 3. The controller 10 may turn on multiple of the charging relays C1 to Cn and multiple negative relays N1 to Nn and diagnose whether the charging relays C1 to Cn and the negative relays N1 to Nn are stuck off using the same method as described above.

[0021] The following describes the function of managing the states of the capacitor 3 and the battery packs B1 to Bn. While the controller 10 is charging the capacitor 3 with the charging relays C1 to Cn and the negative electrode relays N1 to Nn turned on, it acquires the detected voltage from the voltage sensor 5 and manages the charging state of the capacitor 3. When the charging state of the capacitor 3 reaches full charge, the controller 10 switches the positive electrode relays P1 to Pn from off to on and switches the charging relays C1 to Cn off.

[0022] Next, the method for diagnosing a stuck state according to this embodiment will be described. Fig. 2 is a flowchart showing the steps of the method for diagnosing a stuck state. When the vehicle starts, the controller 10 executes the control flow shown in Fig. 2.

[0023] In step S1, the controller 10 turns on all of the charging relays C1 to Cn and diagnoses whether the negative relays N1 to Nn are stuck on. If the controller 10 determines that a stuck-on state has occurred, it may notify the user by displaying a warning light or the like. Alternatively, it may turn on all of the negative relays N1 to Nn and diagnose whether the charging relays C1 to Cn are stuck on.

[0024] In step S2, the controller 10 selects one relay from among the plurality of negative relays N1 to Nn and the plurality of charging relays C1 to Cn as a diagnostic relay. The diagnostic relay refers to a relay to be diagnosed for a stuck-off state during the vehicle startup sequence. The vehicle startup sequence is a control sequence executed by the controller 10 from the time the vehicle's main switch is turned on until the precharge of the controller 10 is completed. The diagnostic relay may be the relay diagnosed as stuck-on in the control flow of step S1. Note that the diagnostic relay is not limited to the negative relays N1 to Nn, but may also be the charging relays C1 to Cn. For example, if the controller 10 turns on all negative relays N1 to Nn and diagnoses the charging relays C1 to Cn as stuck-on in step S1, the controller 10 selects one of the charging relays C1 to Cn as a diagnostic relay in step S2. When the controller 10 determines a diagnostic priority circuit (described later), the controller 10 selects one of the negative relays N1 to Nn included in the diagnostic priority circuit as a diagnostic relay.

[0025] The controller 10 may select a diagnostic relay according to a predetermined diagnostic order. For example, the controller 10 may select a diagnostic relay according to the arrangement order of the battery pack circuits M1 to Mn. Specifically, if the controller 10 selected the negative electrode relay N1 as the diagnostic relay in the previous control flow of step S3, the controller 10 may select the negative electrode relay N2 as the diagnostic relay in the current control flow of step S3. The controller 10 may also select a diagnostic relay randomly, regardless of the arrangement order of the battery pack circuits M1 to Mn. For example, the battery pack circuits M1 to Mn may be assigned numbers rather than the arrangement order, and the controller 10 may select a diagnostic relay in the order of those numbers.

[0026] In step S3, the controller 10 charges the capacitor 3 with one diagnostic relay turned on and the charging relays C1 to Cn paired with that diagnostic relay turned on. All of the charging relays C1 to Cn were turned on during the stuck-on diagnosis in step S1, and all of the charging relays C1 to Cn are maintained in the on state. Therefore, when the control flow in step S3 is executed, one charging relay C1 to Cn paired with one diagnostic relay is turned on, and the other charging relays C1 to Cn not paired with that diagnostic relay are also turned on. If a charging relay C1 to Cn is selected as the diagnostic relay, the controller 10 charges the capacitor 3 with one diagnostic relay turned on and the negative relays N1 to Nn paired with that diagnostic relay turned on.

[0027] In step S4, the controller 10 diagnoses whether the charging relays C1 to Cn and the diagnostic relay are stuck-off, depending on the charging state of the capacitor 3. The controller 10 may manage the charging state of the capacitor 3 based on the detected voltage of the voltage sensor 5 and / or the detected current of the current sensors S1 to Sn. For example, if the detected voltage of the voltage sensor 5 does not increase with the charging relay C1 and the negative relay N1 turned on, the controller 10 determines that the charging relay C1 and / or the negative relay N1 is stuck-off. Note that the controller 10 may also determine that the charging relay C1 and / or the negative relay N1 is stuck-off if the detected current of the current sensor S1 is equal to or less than a predetermined value with the charging relay C1 and the negative relay N1 turned on. Note that if the controller 10 determines that a stuck-off state has occurred, the controller 10 may notify the user by, for example, displaying a warning light.

[0028] In step S5, regardless of the results of the stuck-off diagnosis of the charging relays C1 to Cn and the diagnostic relay in the control flow of step S4, the controller 10 turns on all of the charging relays C1 to Cn and all of the negative electrode relays N1 to Nn to charge the capacitor 3. That is, if it is determined in the control flow of step S4 that the capacitor 3 is charged and the relays are normal, the controller 10 turns on all of the charging relays C1 to Cn and all of the negative electrode relays N1 to Nn to charge the capacitor 3.

[0029] FIG. 3 is a graph showing the voltage transition from when the relay is determined to be normal in the stuck-off diagnosis in step S4 until the capacitor 3 is fully charged. In FIG. 3, Vth is the determination threshold for the stuck-off diagnosis. Vm is the voltage of the capacitor 3 when fully charged. In the stuck-off diagnosis in step S4, if the voltage of the capacitor 3 is less than the determination threshold (Vth), the controller 10 determines that the charging relay C1 and / or the negative relay N1 is stuck-off. As shown in FIG. 3, the capacitor 3 is charged by the charge control in step S3 until the voltage of the capacitor 3 reaches the determination threshold (Vth). Then, after the voltage of the capacitor 3 reaches the determination threshold (Vth), the capacitor 3 is charged by the charge control in step S5.

[0030] Furthermore, in the control flow of step S4, if the voltage of the capacitor 3 does not increase even after a certain period of time has elapsed and it is determined that the charging relay C1 and / or the negative relay N1 is stuck off, all of the charging relays C1 to Cn and all of the negative relays N1 to Nn are turned on to charge the capacitor 3. In other words, even if it is determined from the diagnosis results that some of the charging relays C1 to Cn or some of the negative relays N1 to Nn are stuck off, other normal charging relays C1 to Cn or other negative relays N1 to Nn are turned on to charge the capacitor 3.

[0031] Figure 4 is a graph showing the voltage transition from when the relay is determined to be stuck off in the sticking diagnosis of step S4 until the capacitor 3 is fully charged. Vth and Vm in Figure 4 are the same as those in Figure 3. As shown in Figure 4, if the diagnostic relay and / or the relay paired with the diagnostic relay is stuck off, the voltage of the capacitor 3 does not increase during the stuck-off diagnosis. After the stuck-off diagnosis, the capacitor 3 is charged to full charge by the charging control of step S5.

[0032] Returning to FIG. 2 , in step S6, while the capacitor 3 is being charged by the charge control of step S5, the controller 10 diagnoses whether all of the charging relays C1-Cn and all of the negative electrode relays N1-Nn are stuck-off based on the detected currents of all of the current sensors S1-Sn. The controller 10 detects the currents flowing through the multiple assembled battery circuits M1-Mn using all of the current sensors S1-Sn. While the capacitor 3 is being charged, the controller 10 determines whether the currents detected by the current sensors S1-Sn are equal to or less than a predetermined value. If the detected currents of the current sensors S1-Sn are equal to or less than the predetermined value, the controller 10 determines that the charging relays C1-Cn and / or negative electrode relays N1-Nn included in the same assembled battery circuit M1-Mn as the current sensor S1-Sn whose detected current is equal to or less than the predetermined value are stuck-off.

[0033] In step S7, the controller 10 determines whether or not there is a relay that is stuck off based on the diagnosis result of step S4 or the diagnosis result of step S6. If there is a relay that is stuck off, the controller 10 executes the control flow of step S8, and if there is no relay that is stuck off, the controller 10 executes the control flow of step S9.

[0034] If there is a relay that is stuck off, in step S8, the controller 10 determines the battery pack circuits M1-Mn whose detected current is equal to or less than a predetermined value, i.e., the battery pack circuits M1-Mn including the relay diagnosed as stuck off, as the diagnosis priority circuits. The diagnosis priority circuits indicate circuits that will be prioritized for diagnosis during the next stuck-off diagnosis. When the next vehicle startup is performed, the controller 10 selects one of the negative relays N1-Nn or the charging relays C1-Cn included in the diagnosis priority circuit as the diagnostic relay when executing charging control of the capacitor 3 for the stuck-off diagnosis according to the control flow in step S3. That is, each time the vehicle is started, the controller 10 charges the capacitor 3 with one diagnostic relay and the charging relays C1-Cn or the negative relays N1-Nn paired with the diagnostic relay turned on, and diagnoses the relay for stuck-off. However, if there is no diagnosis priority circuit, the controller 10 selects a diagnostic relay according to, for example, a predetermined diagnosis order. If a diagnosis priority circuit has been determined when the vehicle is started, the controller 10 selects, as the diagnostic relay, a charging relay C1 to Cn or a negative relay N1 to Nn included in the diagnosis priority circuit, regardless of the predetermined diagnosis order. When performing the stuck-off diagnosis in step S4, all of the charging relays C1 to Cn may be turned on, or only one charging relay C1 to Cn paired with the diagnostic relay may be turned on. In other words, it is sufficient that at least one charging relay C1 to Cn paired with the diagnostic relay is turned on.

[0035] As described above, the fixation diagnosis method according to this embodiment includes a selection step of selecting, as a diagnostic relay, one of the plurality of negative electrode relays N1 to Nn and the plurality of charging relays C1 to Cn included in each of the plurality of assembled battery circuits M1 to Mn; a step of charging the capacitor 3 with one diagnostic relay turned on and the charging relay C1 to Cn or negative electrode relay N1 to Nn paired with the one diagnostic relay turned on each time the vehicle is started; and a step of diagnosing whether the charging relays C1 to Cn and the negative electrode relays N1 to Nn are stuck off according to the charge state of the capacitor 3.

[0036] Furthermore, in the sticking diagnostic device according to this embodiment, the controller 10 selects one of the plurality of negative electrode relays N1 to Nn and the plurality of charging relays C1 to Cn included in each of the plurality of assembled battery circuits M1 to Mn as a diagnostic relay, and each time the vehicle is started, the controller 10 turns on one diagnostic relay, and charges the capacitor 3 with the charging relay C1 to Cn or the negative electrode relay N1 to Nn paired with the selected diagnostic relay turned on, and diagnoses whether the charging relays C1 to Cn and the negative electrode relays N1 to Nn are stuck off according to the charge state of the capacitor 3.

[0037] In this embodiment, a stuck-off diagnosis is performed for one battery pack circuit M1-Mn each time the vehicle is started. After the stuck-off diagnosis, the capacitor 3 is charged with the power of all the battery packs B1-Bn. That is, only one diagnostic relay is selected each time the vehicle is started, and the remaining negative electrode relays N1-Nn and charging relays C1-Cn are individually diagnosed for stuck-off status the next time the vehicle is started. For example, as a reference example, the control flow of steps S3 and S4 may be modified to perform a stuck-off diagnosis for all battery pack circuits M1-Mn at the start of the vehicle, rather than just for one battery pack circuit M1-Mn. However, a stuck-off diagnosis such as the reference example requires switching the charging relays C1-Cn and negative electrode relays N1-Nn on and off for all charging relays C1-Cn and all negative electrode relays N1-Nn, which increases the number of relay on / off switching and lengthens the diagnosis time. On the other hand, in this embodiment, a stuck-off diagnosis is performed on one battery pack circuit M1 to Mn each time the vehicle is started, so the number of times the relay is switched on and off is reduced, thereby shortening the diagnosis time.

[0038] In this embodiment, the multiple battery pack circuits M1-Mn are connected in parallel and connected to the capacitor 3. Therefore, if the relays of at least one of the multiple battery pack circuits M1-Mn are normal, the capacitor 3 can be charged. Therefore, in this embodiment, the targets of the stuck-off diagnosis at vehicle start are the charging relays C1-Cn and negative relays N1-Nn included in one battery pack circuit M1-Mn. That is, after determining that the charging relays C1-Cn and negative relays N1-Nn included in one battery pack circuit M1-Mn are normal, the stuck-off diagnosis priority of the other charging relays C1-Cn and negative relays N1-Nn is lowered, and a stuck-off diagnosis of the lowered priority relays is performed from the next start onwards. This shortens the diagnosis time at vehicle start and accelerates the start of charging of the capacitor 3.

[0039] In this embodiment, the power supply circuit is configured by connecting multiple battery pack circuits M1 to Mn in parallel, which allows it to meet higher output requirements compared to a power supply circuit configured with a single battery pack circuit.

[0040] The fixation diagnosis method according to this embodiment also includes a step of diagnosing whether the charging relays C1 to Cn and the negative relays N1 to Nn are stuck on before diagnosing whether the charging relays C1 to Cn and the negative relays N1 to Nn are stuck off. This allows relays that may be stuck on to be diagnosed preferentially in the off diagnosis.

[0041] Furthermore, regardless of the diagnostic result of whether the charging relays C1 to Cn and the negative electrode relays N1 to Nn are stuck-off, the fixation diagnosis method according to this embodiment includes, after diagnosing that they are stuck-off, a step of turning on all of the charging relays C1 to Cn and all of the negative electrode relays N1 to Nn to charge the capacitor 3. As a result, even if some of the charging relays C1 to Cn or the negative electrode relays N1 to Nn are stuck-off, the capacitor 3 can be charged and the vehicle can be made runnable.

[0042] The fixation diagnosis method according to this embodiment includes a detection step of detecting the current flowing through each of the plurality of battery pack circuits M1-Mn using all current sensors S1-Sn included in the plurality of battery pack circuits M1-Mn, and a determination step of determining, while the capacitor 3 is being charged, the battery pack circuits M1-Mn in which the current detected by the current sensors S1-Sn is equal to or less than a predetermined value as the diagnosis priority circuit. When diagnosing a fixation at the start of the vehicle, the negative relays N1-Nn included in the diagnosis priority circuit are selected as the diagnostic relay. This shortens the time that a charging relay C1-Cn or a negative relay N1-Nn is left unattended after it is stuck off.

[0043] As a first modification of this embodiment, when there are multiple diagnostic priority circuits, the controller 10 may select multiple negative relays N1 to Nn or multiple charging relays C1 to Cn included in the multiple diagnostic priority circuits as diagnostic relays, turn on the multiple diagnostic relays and the multiple negative relays N1 to Nn or charging relays C1 to Cn paired with the multiple diagnostic relays at the start of the vehicle, and diagnose whether the multiple negative relays N1 to Nn and the multiple charging relays C1 to Cn are stuck-off according to the charge state of the capacitor 3. For example, if it is determined that there is no diagnostic priority circuit (if the control flow in step S7 above returns "No") or if it is determined that there is one diagnostic priority circuit, the controller 10 turns on one diagnostic relay and performs a stuck-off diagnosis when executing the control flow in steps S2 to S4 at the next startup. On the other hand, if it is determined that there are two or more diagnostic priority circuits, the controller 10 selects, as a diagnostic relay, one of the negative relays N1 to Nn or one of the charging relays C1 to Cn included in the multiple diagnostic priority circuits when executing the control flow of steps S2 to S4 at the next startup. Then, the controller 10 turns on at least one of the multiple diagnostic relays, the negative relay C1 to Cn or the negative relay N1 to Nn paired with at least one of the negative relays N1 to Nn or one of the charging relays C1 to Cn, to charge the capacitor 3. Note that when charging the capacitor 3, all of the charging relays C1 to Cn, including the charging relay C1 to Cn paired with the diagnostic relay, or all of the negative relays N1 to Nn, including the negative relay N1 to Nn paired with the diagnostic relay, may be turned on, or only one charging relay C1 to Cn paired with the diagnostic relay or one negative relay N1 to Nn paired with the diagnostic relay may be turned on. The controller 10 diagnoses whether at least one of the diagnostic relays and the paired charging relays C1 to Cn or negative relays N1 to Nn are stuck-off, depending on the charge state of the capacitor 3. After completing the stuck-off diagnosis of one of the diagnostic relays, the controller 10 similarly performs stuck-off diagnosis on the other diagnostic relays included in the plurality of diagnostic relays. That is, in the first modification, the controller 10 performs stuck-off diagnosis on all relays with high diagnostic priority during one vehicle start sequence.

[0044] As a specific example, assume that in the control flow of step S8, battery pack circuits M1 and Mn are determined to be diagnosis priority circuits. Furthermore, assume that the diagnostic relay order for the current vehicle startup was battery pack circuit M2. If the predetermined diagnostic order was followed, the controller 10 would turn on the negative relay N2 and charging relay C2 during the current vehicle startup and diagnose whether the negative relay N2 and charging relay C2 are stuck off. In Modification 1, instead of following the predetermined diagnostic order, the controller 10 turns on the negative relays N1, Nn and charging relays C1, Cn during the current vehicle startup and, while charging the capacitor 3, diagnoses whether the negative relays N1, Nn and charging relays C1, Cn are stuck off based on the detected voltage of capacitor 3 and the detected currents of current sensors S1 to Sn. For example, if the detected voltage of the capacitor 3 rises while the capacitor 3 is being charged and the current detected by the current sensor S1 is equal to or less than a predetermined value, the controller 10 determines that at least one of the charging relay C1 and the negative electrode relay N1 is stuck off. This makes it possible to shorten the time that the charging relays C1 to Cn or the negative electrode relays N1 to Nn are left stuck off.

[0045] In the first modification, in order to diagnose whether the multiple charging relays C1 to Cn and the multiple diagnostic relays are stuck-off in accordance with the charge state of the capacitor 3, the controller 10 may diagnose whether the multiple charging relays C1 to Cn and the multiple negative relays N1 to Nn are stuck-off by turning on each of them one by one, or may diagnose whether the multiple charging relays C1 to Cn and the multiple negative relays N1 to Nn are stuck-off by turning on the multiple charging relays C1 to Cn and the multiple negative relays N1 to Nn simultaneously. Also, all of the charging relays C1 to Cn and the negative relays N1 to Nn, including the multiple diagnostic relays, may be turned on to perform the stuck-off diagnosis.

[0046] In a second modification of this embodiment, when there are multiple diagnosis priority circuits, the controller 10 may select a predetermined number of diagnostic relays, turn on the predetermined number of diagnostic relays and the plurality of charging relays C1 to Cn or negative relays N1 to Nn paired with the predetermined number of diagnostic relays at the start of the vehicle, and diagnose whether the predetermined number of charging relays C1 to Cn or negative relays N1 to Nn are stuck-off according to the charge state of the capacitor 3. The predetermined number of selections is the upper limit number of relays for which the diagnostic time required to diagnose whether the relays are stuck-off is within a predetermined time threshold. For example, the predetermined time threshold is a predetermined upper limit diagnostic time at the start of the vehicle. The upper limit diagnostic time is the upper limit of the time from when the vehicle's main switch is turned on until the vehicle is ready to run, and is set according to the time acceptable to the user. The number of battery pack circuits M1 to Mn that can be diagnosed at the start of the vehicle corresponds to the number of loops when the control flow of steps S2 to S4 is repeatedly executed.

[0047] As a specific example, assume that three battery pack circuits M1-Mn are determined to be diagnosis priority circuits in the control flow of step S8. Also assume that the predetermined selection number, i.e., the upper limit of the number of battery pack circuits that can be diagnosed during one vehicle start, is two. During the current vehicle start, the controller 10 turns on the charging relays C1-Cn and negative relays N1-Nn included in the two battery pack circuits M1-Mn and diagnoses whether the charging relays C1-Cn and negative relays N1-Nn are stuck off. It is recommended that the diagnosis priority circuits that were not subject to diagnosis during the current vehicle start (one charging relay C1-Cn and one negative relay N1-Nn) be diagnosed during the next vehicle start. This shortens the time until vehicle start preparations are complete.

[0048] As a third modification of this embodiment, the controller 10 may determine, among the multiple assembled battery circuits M1-Mn, the assembled battery circuits M1-Mn including the current sensors S1-Sn that may be abnormal as the diagnosis priority circuits based on the detected voltage of the voltage sensor 5 and the detected current of the current sensors S1-Sn. For example, when executing the control flow of step S3, the controller 10 diagnoses whether the charging relay C1 and the negative relay N1 are stuck off based on the detected voltage of the voltage sensor 5 and the detected current of the current sensor while the charging relay C1 and the negative relay N1 are turned on. If the detected current of the current sensor S1 is equal to or less than a predetermined value, the controller 10 determines whether the capacitor 3 is being charged based on the detected voltage of the voltage sensor 5. If the detected current of the current sensor S1 is equal to or less than the predetermined value and the detected voltage of the voltage sensor 5 is increasing, the charging relay C1 and the negative relay N1 are in a normal state, and an abnormality may have occurred in the current sensor S1. That is, when the detected current of the current sensor S1 is equal to or less than a predetermined value and the detected voltage of the voltage sensor 5 is rising, the controller 10 determines that the battery pack circuit M1 is the diagnosis priority circuit. The diagnosis priority circuit M1 may then be given priority for diagnosis the next time the vehicle is started. When the vehicle is next started, the battery pack circuit M1 is diagnosed again, and if an abnormality in the current sensor S1 is determined, the controller 10 may notify the user of the abnormality by displaying a warning light or the like. Furthermore, because the current sensors S1 to Sn that may be abnormal cannot be used to diagnose a lock, the controller 10 may diagnose a lock in the battery pack circuits M2 to Mn other than the battery pack circuit M1.

[0049] As described above, in Modification 3, if the result of the relay fixation diagnosis indicates that the diagnosis cannot be continued due to an abnormality in one of the current sensors S1 to Sn, the relay to be diagnosed is determined according to the progress of the diagnosis the next time the vehicle is started. This makes it possible to shorten the time that the current sensor S1 to Sn is left undiagnosed after the abnormality occurs.

[0050] In this embodiment, the controller 10 may select a diagnostic relay based on the number of times a fixation diagnosis is performed according to the control flow of steps S2 to S4. As a specific example, assume that the power supply circuit is composed of three parallel battery pack circuits M1 to M3. Assume that the battery pack circuits M1 to M3 are arranged in the following order: battery pack circuit M1 is first, battery pack circuit M2 is second, and battery pack circuit M3 is third. When starting the vehicle, the controller 10 counts the number of times a fixation diagnosis is performed according to the control flow of steps S2 to S4. In the control flow of step S2, the controller 10 selects a diagnostic relay using the remainder obtained by dividing the number of times a fixation diagnosis is performed by the number (n) of parallel battery pack circuits M1 to Mn. For example, after completing 78 diagnoses, the next time the vehicle is started, the 79th diagnosis will be performed. When starting the vehicle, the controller 10 executes the control flow of step S2. The controller 10 selects the negative relay N1 or the charging relay C1 included in the first battery pack circuit M1 as the diagnostic relay based on the remainder (1) of the result of dividing the number of times of fixation diagnosis (79) by the number of parallel circuits (3) of the battery pack circuits M1 to M3 (79 divided by 3 = 26, remainder 1). Note that, since the remainder is 2 at the 80th diagnosis, the negative relay N2 or the charging relay C2 included in the second battery pack circuit M2 is selected as the diagnostic relay. That is, at the (n+1)th diagnosis, the negative relay N1 or the charging relay C1 included in the first battery pack circuit M1 is selected as the diagnostic relay. At the (n+2)th diagnosis, the negative relay N2 or the charging relay C2 included in the second battery pack circuit M2 is selected as the diagnostic relay. At the (n+3)th diagnosis, the negative relay N3 or the charging relay C3 included in the third battery pack circuit M3 is selected as the diagnostic relay. This allows the charging relays C1 to Cn and the negative electrode relays N1 to Nn to be diagnosed in sequence as the vehicle starts.

[0051] In this embodiment, the power supply circuit included in the vehicle power supply system 1 is not limited to the circuit configuration shown in FIG. 1 and may have other circuit configurations. For example, the battery packs B1-Bn do not necessarily have to be provided in each of the battery pack circuits M1-Mm. For example, the battery packs B1-Bn may be connected in series or in parallel to form a single battery, and the single battery may be connected to a parallel circuit of the battery pack circuits M1-Mm that does not include the battery packs B1-Bn. Furthermore, the battery pack circuits M1-Mm may be divided into a first parallel circuit including charging relays C1-Cn, charging resistors R1-Rn, and positive relays P1-Pn, and a second parallel circuit including negative relays N1-Nn. Furthermore, a battery formed by connecting the battery packs B1-Bn in series or in parallel may be connected between the first parallel circuit and the second parallel circuit.

[0052] In this embodiment, the controller 10 does not need to execute all of the control flows shown in Fig. 2, and some of the control flows may be omitted, or the order of the control flows may be changed. For example, the control flow of step S1 may be omitted, and a diagnostic relay may be selected without executing the stuck-on diagnosis.

[0053] REFERENCE SIGNS LIST 1 Vehicle power supply system 2 Inverter 3 Capacitor 5 Voltage sensor 10 Controller B1 to Bn Assembled battery C1 to Cn Charging relay M1 to Mn Assembled battery circuit N1 to Nn Negative electrode relay P1 to Pn Positive electrode relay R1 to Rn Charging resistor

Claims

1. A method for diagnosing a stuck state of a relay included in a power supply circuit mounted on a vehicle, wherein the power supply circuit has: an assembled battery parallel circuit in which assembled battery circuits, each including a positive relay, a negative relay, a charging relay, and a charging resistor, are connected in parallel; a capacitor connected in parallel to the assembled battery parallel circuit; and an assembled battery electrically connected to the assembled battery circuit and the capacitor, wherein the assembled battery circuit has: the positive relay connected in parallel to a series circuit that connects the charging relay and the charging resistor in series; and the negative relay connected to a parallel circuit that connects the series circuit and the positive relay in parallel, the sticking state diagnosis method comprising: a selection step of selecting, as a diagnostic relay, one of a plurality of negative relays and a plurality of charging relays included in each of a plurality of the assembled battery circuits; a step of charging the capacitor with one diagnostic relay turned on and the charging relay or negative relay paired with the one diagnostic relay turned on each time the vehicle is started; and a step of diagnosing whether the charging relay and the negative relay are stuck off according to the charge state of the capacitor.

2. A method for diagnosing a stuck state according to claim 1, comprising the step of diagnosing whether the charging relay or the negative relay is stuck in the ON position before diagnosing whether the charging relay and the negative relay are stuck in the OFF position.

3. A fixation diagnosis method according to claim 1 or 2, comprising the step of turning on all of the charging relays and all of the negative relays to charge the capacitor, regardless of the diagnostic result that the charging relays and the negative relays are stuck off, after diagnosing that they are stuck off.

4. A method for diagnosing a stuck state as claimed in claim 3, wherein the battery pack circuit has a current sensor connected to the battery pack, and the method includes a detection step of detecting the current flowing through each of the plurality of battery pack circuits using all current sensors included in the plurality of battery pack circuits, and a determination step of determining, during charging of the capacitor, the battery pack circuit in which the current detected by the current sensor is equal to or less than a predetermined value as a diagnosis priority circuit, and the selection step selects the negative relay or the charging relay included in the diagnosis priority circuit as the diagnostic relay.

5. A method for diagnosing a stuck state as claimed in claim 4, wherein, when there are a plurality of said diagnostic priority circuits, the plurality of negative relays or the plurality of charging relays included in a plurality of said diagnostic priority circuits are selected as said diagnostic relays, the plurality of said diagnostic relays and the plurality of charging relays or the plurality of said negative relays paired with said plurality of diagnostic relays are turned on when the vehicle is started, and the plurality of charging relays and the plurality of said negative relays are diagnosed as being stuck off according to the charge state of said capacitor.

6. A method for diagnosing a stuck-off condition as claimed in claim 4, wherein, when there are a plurality of the diagnostic priority circuits, a predetermined number of diagnostic relays are selected, the predetermined number being an upper limit number of relays for which the diagnostic time required to diagnose a relay stuck-off is within a predetermined time threshold, the predetermined number of diagnostic relays and the plurality of charging relays or the plurality of negative relays paired with the predetermined number of diagnostic relays are turned on when the vehicle is started, and the plurality of charging relays or the plurality of negative relays are diagnosed as stuck-off according to the charge state of the capacitor.

7. A method for diagnosing a stuck state as claimed in claim 4, wherein the power supply circuit has a voltage sensor that detects the voltage of the capacitor, and the determining step includes a step of determining, based on the voltage detected by the voltage sensor and the current detected by the current sensor, the battery pack circuit that includes the current sensor that may be abnormal, as the diagnosis priority circuit, among the plurality of battery pack circuits.

8. A sticking diagnostic device comprising: a battery pack parallel circuit in which battery pack circuits including a battery pack, a positive electrode relay, a negative electrode relay, a charging relay, and a charging resistor are connected in parallel; a capacitor connected in parallel to the battery pack parallel circuit; a battery pack electrically connected to the battery pack circuit and the capacitor; and a controller that switches the positive electrode relay, the negative electrode relay, and the charging relay on and off, wherein the battery pack circuit connects the positive electrode relay in parallel to a series circuit that connects the charging relay and the charging resistor in series, and connects the negative electrode relay to a parallel circuit that connects the series circuit and the positive electrode relay in parallel, and the controller selects one relay from among a plurality of negative electrode relays and a plurality of charging relays included in each of a plurality of battery pack circuits as a diagnostic relay, and charges the capacitor with one diagnostic relay turned on and the charging relay or negative electrode relay paired with one diagnostic relay turned on each time the vehicle is started, and diagnoses whether the charging relay and the negative electrode relay are stuck off according to the charge state of the capacitor.

Images