Sticking diagnosis method and sticking diagnosis device

Abstract

The present invention relates to a sticking diagnosis method for a relay included in a power supply circuit. The power supply circuit includes: a battery pack parallel circuit in which a plurality of battery pack circuits M1-Mn are connected in parallel; a capacitor 3 connected in parallel to the battery pack parallel circuit; and battery packs B1-Bn electrically connected to the battery pack circuits M1-Mn and the capacitor 3. The sticking diagnosis method includes: a step of charging a capacitor 3, in a state where charging relays C1-Cn and negative electrode relays N1-Nn are ON, for each of a plurality of connection lines (C, N lines) respectively included in a plurality of battery pack circuits M1-Mn; and a step of diagnosing OFF sticking of the charging relays C1-Cn and the negative electrode relays N1-Nn according to the charging state of the capacitor 3.

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 control devices for power supply circuits that determine whether a relay is welded. For example, in a control device for a power supply circuit described in Patent Document 1, the power supply circuit includes a circuit having a first relay that controls electrical conduction / de-energization between a load and one pole of a power storage mechanism and 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, the circuit configuration of the power supply circuit described in Patent Document 1 has a problem in that it cannot meet high input / output requirements for the battery.

[0005] The problem to be solved by the present invention is to provide a method and apparatus for diagnosing a stuck relay in a power supply circuit that can meet high output requirements.

[0006] The present invention solves the above problem by charging a capacitor with the charging relay and negative electrode relay turned on for each of multiple connection lines included in each of multiple battery pack circuits, 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, it is possible to diagnose whether a relay has stuck in a power supply circuit that can meet high output demands.

[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 pre-charging of the capacitor. Fig. 4 is a graph showing characteristics of a capacitor voltage during pre-charging of the capacitor. Fig. 5 is a graph showing characteristics of input / output values ​​of a battery pack.

[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). The connection lines (C, N lines) correspond to the "relay connection lines" of the present invention.

[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 the converted power 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 charges the capacitor 3 with the charging relays C1 to Cn and the negative electrode relays N1 to Nn turned on for each of the multiple connection lines (C and N lines), and diagnoses whether the charging relays C1 to Cn and the negative electrode relays N1 to Nn are stuck off depending on the charging state of the capacitor.

[0021] The controller 10 diagnoses whether the positive electrode relays P1-Pn and the negative electrode relays N1-Nn are stuck off based on the detected currents detected by the current sensors S1-Sn during discharging or charging of the battery packs B1-Bn in response to input / output requests for the battery packs B1-Bn. When the vehicle starts, the controller 10 turns on the charging relays C1-Cn and the negative electrode relays N1-Nn to start charging the capacitor 3 (pre-charge start). When charging of the capacitor 3 is completed (pre-charge completion), the controller 10 turns on all positive electrode relays P1-Pn and turns off all charging relays C1-Cn. The battery packs B1-Bn input and output power in response to input / output requests. Input / output requests include system requests from the system, such as requests from user operations such as the vehicle's main switch (vehicle start), accelerator, and brake, requests from user operations of auxiliary devices such as the navigation system, charging of the auxiliary battery, and vehicle driving. Examples of input / output requests include DCDC startup current, motor excitation current, and driving / charging current. When an input / output request is made to the battery packs B1-Bn, the controller 10 controls the vehicle load so that the input / output values ​​(input / output power) from the battery packs B1-Bn correspond to the input / output request. The controller 10 detects the current flowing through the battery pack circuits M1-Mn using current sensors S1-Sn while the battery packs B1-Bn are being discharged or charged. If the current detected by the current sensors S1-Sn is equal to or less than a predetermined value, the controller 10 determines that at least one of the positive electrode relays P1-Pn and the negative electrode relays N1-Nn is stuck off. The controller 10 may diagnose whether the positive electrode relays P1-Pn and the negative electrode relays N1-Nn are stuck off based on the current detected by the current sensors S1-Sn while the battery packs B1-Bn are being charged.

[0022] 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.

[0023] 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. The controller 10 executes the control flow shown in Fig. 2.

[0024] In step S1, the controller 10 determines that the vehicle has been started. If the vehicle has not been started, the controller 10 enters a sleep state, and the control flow waits in step S1. The controller 10 determines that the vehicle has been started by receiving an ON command for the main switch (ignition switch) of the vehicle.

[0025] In step S2, the controller 10 turns on all negative relays N1 to Nn. In step S3, the controller 10 sets the on-time (Ton_m) and voltage threshold (Vth_m) of the charging relays C1 to Cn according to the results of the previous stuck-off diagnosis. In this embodiment, the controller 10 executes the pre-charge and stuck-off diagnosis sequentially, starting with the connection line (C, N line) included in the first assembled battery circuit M1 and continuing through the connection line (C, N line) included in the nth assembled battery circuit Mn. m indicates the order (diagnosis line number) of the connection lines targeted for the pre-charge and stuck-off diagnosis and is represented by a natural number from 1 to n. Note that m starts at "1" and increases by 1 for each cycle of the control loop from steps S3 to S7.

[0026] The previous diagnosis result of a stuck-off state corresponds to the diagnosis result in the control flow of step S6. The on-time (Ton_m) is the time for which one charging relay is turned on, and corresponds to the charging time for charging capacitor 3 with one battery pack B1-Bn. It is determined in advance based on the resistance values ​​of charging resistors R1-Rn, the capacitance of capacitor 3, and the like. The voltage threshold (Vth_m) corresponds to the target voltage when capacitor 3 is charged with one battery pack B1-Bn. Capacitor 3 is charged until the voltage of capacitor 3 reaches the voltage threshold (Vth_m). Note that if battery packs B1-Bn are the same batteries, such as in terms of battery capacity, charging resistors R1-Rn have the same resistance value, and no stuck-off state occurs in charging relays C1-Cn, the voltage threshold (Vth_m) increases by a fixed voltage as m increases. In the initial state (m=1), the controller 10 sets the on-time (Ton_1) and voltage threshold (Vth_1) of the charging relay P1 to initial values ​​(To, Vo), respectively. Note that in the following explanation and in the notation of Figures 3 and 4, for ease of explanation, the on-time (Ton_m) of each of the charging relays C1 to Cn is set to the same time, but as the charging of the capacitor 3 progresses, the charging rate of the capacitor 3 slows down, so it is preferable to lengthen the on-time (Ton_m).

[0027] In step S4, the controller 10 turns off the (m-1)th charging relay Cm-1 and turns on the mth charging relay Cm to charge the capacitor 3. The controller 10 also measures the charging time of the capacitor 3. In step S5, the controller 10 determines whether the measured charging time has reached the on-time (Ton_m) of the charging relay Cm. If the charging time has not reached the on-time (Ton_m) of the charging relay Cm, the control flow returns to step S4, and charging of the capacitor 3 continues until the charging time reaches the on-time (Ton_m) of the charging relay Cm.

[0028] When the charging time reaches the on-time (Ton_m) of the charging relay Cm, the controller 10 diagnoses whether the charging relay Cm and the negative electrode relay Nm are stuck-off, depending on the charging state of the capacitor 3. Specifically, the controller 10 compares the detected voltage (Vm) of the voltage sensor 5 with a voltage threshold (Vth_m), and if the detected voltage (Vm) is equal to or greater than the voltage threshold (Vth_m), determines that the charging relay Cm and the negative electrode relay Nm are not stuck-off. On the other hand, if the detected voltage (Vm) is less than the voltage threshold (Vth_m), the controller 10 determines that either the charging relay Cm or the negative electrode relay Nm is stuck-off. Note that if the detected voltage (Vm) becomes equal to or greater than the voltage threshold (Vth_m) before the charging time reaches the on-time (Ton_m) of the charging relay Cm, the controller 10 may execute step S7 without waiting for the on-time to elapse.

[0029] The controller 10 may diagnose whether the charging relay Cm and the negative relay Nm are stuck off based on the current detected by the current sensor (Sm). If the current detected by the current sensor (Sm) is greater than a predetermined value, the controller 10 determines that the charging relay Cm and the negative relay Nm are not stuck off. If the current detected by the current sensor (Sm) is equal to or less than a predetermined value, the controller 10 determines that either the charging relay Cm or the negative relay Nm is stuck off.

[0030] In step S7, the controller 10 determines whether the stuck-off diagnosis has been completed up to the nth connection line. That is, if m=n is satisfied, it is determined that the stuck-off diagnosis has been completed up to the nth connection line. If the stuck-off diagnosis has not been completed up to the nth connection line, the control flow returns to step S3, and m is incremented by 1.

[0031] After the control flow proceeds to "No" in step S7, when the controller 10 executes the control flow in step S3, it sets the on-time (Ton_m) and the voltage threshold (Vth_m) according to the result of the stuck-off diagnosis (previous diagnosis result) in step S6. If the previous diagnosis result for the stuck-off state is determined to be normal (no stuck-off state has occurred), the on-time (Ton_m) is the same as the previous on-time (Ton_m-1), which is the same as the on-time in the initial state (m = 1). As the charging of the capacitor 3 progresses, the on-time (Ton_m) may be longer than the previous on-time (Ton_m-1). The voltage threshold (Vth_m) is a voltage value obtained by adding a fixed voltage to the previous voltage threshold (Vth_m-1) or the current voltage of the capacitor 3. The fixed voltage corresponds to the increased voltage that increases with each charging of each connection line (C, N).

[0032] On the other hand, if the previous diagnosis result for the stuck-off state is determined to be abnormal (a stuck-off state has occurred), the on-time (Ton_m) is the sum of the previous on-time (Ton_m-1) and the on-time (Ton_1). The voltage threshold (Vth_m) is the sum of the previous voltage threshold (Vth_m-1) and the voltage threshold (Vth_1). In other words, if it is determined that a stuck-off state has occurred in the (m-1)th connection line, the charging time for the mth connection line is twice the charging time for the (m-1)th connection line, and the voltage increase due to charging of the capacitor 3 is twice the increase in voltage per connection line. In reality, the charging time becomes longer as the charging of the capacitor 3 progresses, and the on-time (Ton_m) may be longer than the sum of the previous on-time (Ton_m-1) and the on-time (Ton_1), and the charging time for the mth connection line may be longer than twice the charging time for the (m-1)th connection line.

[0033] When the stuck-off diagnosis has been completed up to the nth connection line, the controller 10 determines whether the voltage of the capacitor 3 has reached full charge (step S8). In the control flow from steps S3 to S7, if a stuck-off occurs on the nth control line, the capacitor 3 has not reached full charge. Therefore, in step S9, the controller 10 turns on all charging relays C1 to Cn, or charging relays C1 to Cn determined not to be stuck-off, to charge the capacitor 3 to full charge. In other words, when a fixed-off relay is diagnosed to have occurred on the nth connection line (C, N line), the controller 10 executes the control flow of step S9 to turn on all charging relays C1 to Cn and all negative relays N1 to Nn, thereby charging the capacitor 3 to full charge.

[0034] If it is determined in the determination flow of step S8 that the battery has reached full charge, or if the capacitor 3 has been fully charged in the control flow of step S9, the controller 10 turns on all positive relays P1 to Pn in step S10. In step S11, the controller 10 turns off all charging relays C1 to Cn. When the control flow of step S11 is executed, the vehicle power supply state ends the Ready On state. The controller 10 then controls the vehicle load so that the input / output values ​​(input / output power) from the battery packs B1 to Bn correspond to the input / output requirements. In step S12, the controller 10 diagnoses whether the positive relays P1 to Pn and the negative relays N1 to Nn are stuck-off based on the detected currents detected by the current sensors S1 to Sn. The controller 10 may repeatedly execute the stuck-off diagnosis of step S12 until the vehicle's main switch is turned off. If the result of the stuck-off diagnosis in step S6 indicates that either the charging relays C1 to Cn or the negative electrode relays N1 to Nn are stuck-off in all of the first to nth connection lines, the controller 10 executes the vehicle stop mode.

[0035] Next, a time chart of the on / off states of the charging relays C1 to Cn and the capacitor voltage when either the charging relay C2 or the negative relay N2 is stuck off will be described with reference to Fig. 3. Fig. 3 is a graph showing the characteristics of the capacitor voltage during precharging of the capacitor 3 after the vehicle starts. The time chart shown in Fig. 3 corresponds to the voltage characteristics of the capacitor 3 when the control flow from step S2 to step S8 in Fig. 2 is executed.

[0036] The controller 10 sets the on-time (Ton_1) and voltage threshold (Vth_1) of the charging relay C1 as the initial state. When the charging relay C1 is on for the on-time (Ton_1), the voltage of the capacitor 3 rises. After the on-time (Ton_1) has elapsed, the voltage of the capacitor 3 becomes equal to or close to the voltage threshold (Vth_1), and precharging using the first connection line (C, N) ends. The charging relay C1 changes from on to off, and after a predetermined off-time (Toff_1) has elapsed, the charging relay C2 changes from off to on. The off-time (Toff_1) is set to prevent interference between the on-off of adjacent charging relays C1 to Cn and is set to a time longer than the delay time between the on-off of the charging relays C1 to Cn. The off-time (Toff_1) is the same as the subsequent off-times (Toff_2 to Toff_n-1).

[0037] In the example of FIG. 3 , either the charging relay C2 or the negative relay N2 is stuck off. Therefore, even if the off time (Toff_1) elapses and the controller 10 controls the charging relay C2 to switch from off to on, the second connection line (C, N) does not conduct, and the voltage of the capacitor 3 does not increase. The voltage threshold (Vth_2) for determining whether the second connection line (C, N) is stuck off is a value obtained by adding a certain voltage to the previous voltage threshold (Vth_1). When the on time (Ton_2) elapses, the voltage V2 of the capacitor 3 becomes lower than the voltage threshold (Vth_2), so the controller 10 determines that either the charging relay C2 or the negative relay N2 is stuck off. If the controller 10 determines that a stuck-off state has occurred in the second connection line (C, N), i.e., if the second diagnostic result for the stuck-off state is determined to be abnormal, the controller 10 sets the third on-time (Ton_3) to the sum of the second on-time (Ton_2) and the on-time (Ton_1). Note that the third on-time (Ton_3) may be longer than the sum of the second on-time (Ton_2) and the on-time (Ton_1). The controller 10 also sets the voltage threshold (Vth_3) for determining a stuck-off state to the sum of the second voltage threshold (Vth_2) and the voltage threshold (Vth_1).

[0038] After a predetermined off-time (Toff_2) has elapsed, the charging relay C3 changes from off to on. The third on-time (Ton_3) is set to a time equivalent to twice the first on-time (Ton_1). Note that the third on-time (Ton_3) may be longer than twice the first on-time (Ton_1). When the on-time (Ton_3) has elapsed, the voltage (V3) of the capacitor 3 becomes equal to or close to the voltage threshold (Vth_3), and precharging using the third connection line (P, N) ends. Because the voltage (V3) of the capacitor 3 is equal to or greater than the voltage threshold (Vth_3), the controller 10 determines that the charging relay C3 and the negative electrode relay N3 are not stuck off and that the relays of the third connection line (C, N line) are normal.

[0039] Then, when the final on-time (Ton_n) has elapsed, the voltage Vn of the capacitor 3 becomes equal to or close to the voltage threshold (Vth_n), and precharging using the nth connection line (C, N) ends. This ends precharging using all the connection lines (C, N), and precharging of the capacitor 3 ends.

[0040] In the above example, if it is determined that the relay of the mth connection line (C, N line) is stuck off, the on time (Ton_m+1) of the charging relay Cm+1 is lengthened when precharging the m+1th connection line. That is, to make up for the charge that was not possible due to the stuck off relay, the precharge time of the next connection line (C, N line) is lengthened. The precharge time is not limited to the line next to the connection line diagnosed as stuck off, as in the above example, but may also be lengthened for another connection line (C, N line). An example of lengthening the on time (Ton_n) of the charging relay when precharging the nth connection line (C, N line) will be described with reference to FIG. 4 .

[0041] FIG. 4 is a graph showing a time chart of the on / off states of the charging relays C1 to Cn and the capacitor voltage. In the example of FIG. 4 , similar to FIG. 3 , either the charging relay C2 or the negative relay N2 is stuck-off. In the example of FIG. 4 , when it is determined that the second connection line (C, N line) is stuck-off, the controller 10 sets the third on-time (Ton_3) to the same time as the second on-time (Ton_2) and sets the voltage threshold (Vth_3) to the same value as the second voltage threshold (Vth_2). Then, when precharging the nth connection line (C, N line), the controller 10 sets the nth on-time (Ton_n) to the n-1th on-time (Ton_n-1) plus the on-time (Ton_1 or Ton_m-2). As the charging of the capacitor 3 progresses, the on-time (Ton_m) may be made longer than the previous on-time (Ton_m-1), or the nth on-time (Ton_n) may be made longer than the sum of the on-time (Ton_1 or Ton_m-2) and the on-time (Ton_n-1) for the n-1th time. The controller 10 also sets the voltage threshold (Vth_n) for determining a stuck-off state to the sum of the voltage threshold (Vth_n-2) for the n-1th time. After the final on-time (Ton_n), the voltage Vn of the capacitor 3 becomes equal to or close to the voltage threshold (Vth_n), and precharging using the nth connection line (P, N) is completed. This completes precharging using all the connection lines (P, N), and precharging of the capacitor 3 is completed.

[0042] In the example of FIG. 4 , if the relay on the nth connection line (C, N line) is also stuck off in addition to the second connection line (C, N line), the capacitor 3 cannot be fully charged by precharging on the nth connection line (C, N line). Therefore, for example, the controller 10 diagnoses that the relay on the nth connection line (C, N line) is not stuck off by confirming that the capacitor 3 is being charged based on the detected voltage of the voltage sensor 5 during precharging on the nth connection line (C, N line). Then, after confirming that the relay on the nth connection line (C, N line) is not stuck off, the controller 10 charges the capacitor 3 to full charge.

[0043] That is, in this embodiment, if it is diagnosed that the relay is stuck off in at least one connection line (C, N line) among the 1st to n-1th connection lines (C, N lines), and if it is diagnosed that the relay is not stuck off in the nth connection line (C, N line), the controller 10 charges the capacitor 3 to full charge with the charging relay Cn and negative relay Pn included in the nth connection line (C, N line) turned on.

[0044] As described above, in the fixation diagnosis method according to this embodiment, the power supply circuit includes an assembled battery parallel circuit in which a plurality of assembled battery circuits M1 to Mn are connected in parallel, a capacitor 3 connected in parallel to the assembled battery parallel circuit, and assembled batteries B1 to Bn electrically connected to the assembled battery circuits M1 to Mn and the capacitor 3, and the fixation diagnosis method includes the steps of charging the capacitor 3 with the charging relays C1 to Cn and the negative electrode relays N1 to Nn turned on for each of a plurality of connection lines (C, N lines) included in each of the plurality of assembled battery circuits M1 to Mn, and diagnosing whether the charging relays C1 to Cn and the negative electrode relays N1 to Nn are stuck off in accordance with the charge state of the capacitor 3. This makes it possible to diagnose whether the relays are stuck in the off state in a power supply circuit that can handle high output requirements.

[0045] The sticking diagnosis device of this embodiment also includes a battery pack parallel circuit in which a plurality of battery pack circuits M1 to Mn are connected in parallel, a capacitor 3 connected in parallel to the battery pack parallel circuit, and a controller 10, and the controller 10 charges the capacitor 3 with the charging relays C1 to Cn and negative electrode relays N1 to Nn turned on for each of a plurality of connection lines (C, N lines) included in each of the plurality of battery pack circuits M1 to Mn, and diagnoses whether the charging relays C1 to Cn and negative electrode relays N1 to Nn are stuck off according to the charging state of the capacitor 3. This makes it possible to diagnose whether the relays are stuck in a power supply circuit that can meet high output requirements.

[0046] Furthermore, the fixation diagnosis method according to the embodiment includes the steps of turning on a plurality of positive electrode relays P1 to Pn and a plurality of negative electrode relays N1 to Nn included in a plurality of assembled battery circuits M1 to Mn, and diagnosing whether the positive electrode relays P1 to Pn and the negative electrode relays N1 to Nn are stuck off based on the detected currents of the current sensors S1 to Sn. This makes it possible to diagnose whether the positive electrode relays P1 to Pn and the negative electrode relays N1 to Nn are stuck off in a power supply circuit that can meet high output requirements.

[0047] Furthermore, the fixation diagnosis method according to the embodiment includes a step of charging the capacitor C to full charge while turning on the charging relay Cn and the negative relay Nn included in the nth connection line (C, N line), when it is diagnosed that the relay is stuck off in at least one connection line (C, N line) among the 1st to n-1th connection lines (C, N lines) and when it is diagnosed that the relay is not stuck off in the nth connection line (C, N line). This allows the capacitor 3 to be fully charged when the relays of some of the connection lines (C, N lines) are stuck off.

[0048] Furthermore, the fixation diagnosis method according to the embodiment includes a step of turning on all the charging relays C1 to Cn and all the negative electrode relays N1 to Nn and fully charging the capacitor 3 when it is diagnosed that a relay is stuck off in the n-th connection line (C, N lines). This allows the capacitor 3 to be fully charged when a relay in some of the connection lines (C, N lines) is stuck off.

[0049] As a first modification of this embodiment, when diagnosing whether the positive electrode relays P1 to Pn and the negative electrode relays N1 to Nn are stuck in the off state, the controller 10 may compare the predicted values ​​of the charge / discharge currents of the assembled batteries B1 to Bn with the detected values ​​of the current sensors S1 to Sn, and diagnose whether the relays are stuck in the off state based on the comparison result.

[0050] The following describes the stuck-off diagnosis method according to Modification 1. When there is an input / output request for the battery packs B1 to Bn, the controller 10 calculates the total current value (I ｔｏｔａｌ_ｃａｌ ) and the shunt current value (I ｐｎ_ｃａｌ =I ｔｏｔａｌ_ｃａｌ / n) is calculated. ｔｏｔａｌ_ｃａｌ ) is the total value of the current flowing through the battery pack circuits M1 to Mn when the battery packs B1 to Bn output power according to the input / output requirements. ｐｎ_ｃａｌ ) is the total current value (I ｔｏｔａｌ_ｃａｌ ) divided by the number (n) of assembled battery circuits M1 to Mn, and corresponds to the predicted value of the current flowing through one of the assembled battery circuits M1 to Mn.

[0051] The controller 10 also receives the detected values ​​(I ｍ_ｓｃ ) and obtain the detected value (I ｍ_ｓｃ ) the sum of (I ｔｏｔａｌ_ｓｃ =I ｍ_ｓｃ ×n), where m is the number of the connection line (P, N line) and is a natural number greater than or equal to 1 and less than or equal to n. The controller 10 calculates the total current value (I ｔｏｔａｌ_ｃａｌ ) and the sum of the detected values ​​of the current sensors S1 to Sn (I ｔｏｔａｌ_ｓｃ ) and if they are the same, it can be confirmed that the current according to the input / output requirements is flowing through the battery pack circuits M1 to Mn. ｐｎ_ｃａｌ ) and the detected value (I ｍ_ｓｃ ) and if they are the same value, it is determined that none of the positive relays P1 to Pn and negative relays N1 to Nn are stuck off.

[0052] On the other hand, the shunt current value (I ｐｎ_ｃａｌ ) and the detected value (I ｍ_ｓｃ) are different values, the controller 10 detects the number of connection lines (P, N lines) in which the stuck-off state occurs (hereinafter also referred to as the "number of stuck-off lines") using the following two methods. As a first method, the controller 10 calculates the number of normal lines (I ｔｏｔａｌ_ｓｃ / I ｍ_ｓｃ As a second method, the controller 10 calculates the number of stuck-off lines by subtracting the detected value (I ｍ_ｓｃ The number of connection lines (P and N lines) including the current sensors S1 to Sn where the current sensor output voltage (V) is zero amperes (0 A) is calculated as the number of stuck-off lines. The controller 10 can then double-check the stuck-off diagnosis of the connection lines (P and N lines) by confirming that the numbers of stuck-off lines detected by the two methods match. As a result, the accuracy of the stuck-off diagnosis is improved.

[0053] As a second modification of this embodiment, the controller 10 may limit the input / output values ​​of the battery packs B1 to Bn to be equal to or less than a predetermined input / output upper limit value until the diagnosis according to the control flow of step S12 is completed.

[0054] The limitations on input / output values ​​during the stuck-off diagnosis will be described with reference to FIG. 5. FIG. 5 is a graph showing the characteristics of the input / output values ​​of the battery packs B1 to Bn. In FIG. 5, Pn represents the input / output value requested of the battery packs B1 to Bn by user operation or the system. In the example of FIG. 5, it is assumed that an output request is made to the battery packs B1 to Bn to output the maximum output of the vehicle.

[0055] Pc is a predetermined input / output upper limit. Pc is set to a value lower than the maximum input / output value of the components on the circuit and corresponds to the power (current value) at which the components, harnesses, and other components included in the battery pack circuits M1-Mn, on the power supply circuit, do not malfunction or deteriorate. The input / output upper limit (Pc) is set to a value lower than the maximum input / output value of the components on the circuit. If all of the positive relays P1-Pn and negative relays N1-Nn are normal, all battery packs output power according to the input / output requirements. On the other hand, if a fixed-off state occurs in any of the positive relays P1-Pn and negative relays N1-Nn, the battery pack circuits M1-Mn cannot pass current through the fixed-off relays. After starting the vehicle, there is a possibility that a fixed-off state occurs in any of the positive relays P1-Pn and negative relays N1-Nn until the first fixed-off diagnosis is completed. Therefore, when an attempt is made to input or output power from or to the battery packs B1-Bn in response to input / output requests when any of the positive electrode relays P1-Pn and the negative electrode relays N1-Nn is stuck off, the input / output per battery pack B1-Bn becomes larger than when all relays are normal. Furthermore, the input / output per battery pack B1-Bn becomes larger as the number of battery pack circuits M1-Mn in which current cannot flow due to the stuck-off relay increases.

[0056] Therefore, in Modification 2 of this embodiment, an input / output upper limit value (Pc) is set in advance to prepare for the possibility of a stuck-off state until the first stuck-off diagnosis after starting the vehicle is completed. Until the stuck-off diagnosis is completed, the controller 10 compares the input / output demand values ​​for the battery packs B1 to Bn with the input / output upper limit value (Pc), and if the input / output demand values ​​are greater than the input / output upper limit value (Pc), the controller 10 limits the input / output demand values ​​to be equal to or less than the input / output upper limit value (Pc). If the input / output demand values ​​are equal to or less than the input / output upper limit value (Pc), the controller 10 does not limit the input / output demand values. This prevents excessive thermal load from being applied to circuit components until the stuck-off diagnosis of the positive relays P1 to Pn and the negative relays N1 to Nn is completed.

[0057] As shown in FIG. 5 , the controller 10 starts the stuck-off diagnosis at time t0 and ends the first stuck-off diagnosis at time te. During the stuck-off diagnosis, an input / output demand value (Pn) for each battery pack B1 to Bn is input in response to a user operation or a request from the system. Until time te, an input / output upper limit value (Pc) is set, and the controller 10 limits the input / output demand value (Pn) to the input / output upper limit value (Pc). After time te has elapsed, the controller 10 releases the limit on the input / output upper limit value (Pc) and controls the vehicle load so that each battery pack B1 to Bn inputs and outputs the input / output demand value (Pn). Note that, as shown in Modification 3 described below, if a relay is diagnosed as being stuck-off, the controller 10 may limit the input / output demand value (Pn) using a different limiting method from the limiting method of the input / output upper limit value (Pc) according to Modification 2.

[0058] As a third modification of this embodiment, if the controller 10 determines that a relay is stuck-off based on the diagnosis result of the control flow in step S12 while the vehicle is running, the controller 10 may limit the input / output values ​​of the multiple assembled batteries B1 to Bn depending on the number of assembled battery circuits M1 to Mn including the relay determined to be stuck-off. The controller 10 limits the input / output values ​​of the multiple assembled batteries B1 to Bn so that the input / output values ​​are equal to the input / output demand values ​​for the assembled batteries B1 to B3 multiplied by (n - m / n), where m is the number of assembled battery circuits M1 to Mn including the relay that is stuck-off. As a specific example, suppose a power supply circuit is composed of three assembled battery circuits M1 to M3 connected in parallel, and two positive relays P2 and P3 are stuck-off. Furthermore, suppose there is an output demand for 300 A to be output from the assembled batteries B1 to B3. In this specific example, because the two battery pack circuits M2 and M3 include fixed-off relays, the battery packs B2 and B3 cannot output power to the loads, and the output demand must be met only by the battery pack B1. Therefore, the controller 10 multiplies the input / output demand value (300 A) by 1 / 3 to obtain a post-limiting input / output demand value of 100 A, and controls the vehicle load so that the post-limiting input / output demand value is output from the battery pack B1. This prevents excessive thermal load from being applied to a normal relay.

[0059] 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.

[0060] In this embodiment, the method for diagnosing the stuck-off of the charging relays C1 to Cn and the negative relays N1 to Nn may be to turn on all the negative relays N1 to Nn and diagnose the stuck-on of the negative relays N1 to Nn, and then gradually charge the capacitor 3 while turning on and off each of the charging relays C1 to Cn one by one to diagnose the stuck-off of the charging relays C1 to Cn and the negative relays N1 to Nn. Also, the method for diagnosing the stuck-off of the charging relays C1 to Cn and the negative relays N1 to Nn may be to turn on all the charging relays C1 to Cn and diagnose the stuck-on of the charging relays C1 to Cn, and then gradually charge the capacitor 3 while turning on and off each of the negative relays N1 to Nn one by one to diagnose the stuck-off of the charging relays C1 to Cn.

[0061] 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.

[0062] 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 connects the positive relay in parallel to a series circuit that connects the charging relay and the charging resistor in series, and includes a connection line that electrically connects the charging relay and the negative relay in series, the sticking state diagnosis method comprising: a step of charging the capacitor with the charging relay and the negative relay turned on for each of a plurality of the connection lines included in each of a plurality of the assembled battery circuits; and a first diagnostic step of diagnosing whether the charging relay and the negative relay are stuck off depending on the charge state of the capacitor.

2. A method for diagnosing a stuck state according to claim 1, wherein the battery pack circuit has a current sensor, and the method for diagnosing a stuck state includes: a step of turning on a plurality of the positive electrode relays and a plurality of the negative electrode relays included in the plurality of battery pack circuits; and a second diagnostic step of diagnosing whether the positive electrode relays and the negative electrode relays are stuck off based on the current detected by the current sensor.

3. A sticking diagnosis method according to claim 1 or 2, wherein the first diagnostic step is executed for each of the first to nth relay connection lines among the plurality of connection lines, and the sticking diagnosis method includes a step of charging the capacitor to full charge with the charging relay and the negative relay included in the nth relay connection line turned on when it is diagnosed that a relay is stuck off in at least one of the first to n-1th relay connection lines and that a relay is not stuck off in the nth relay connection line, where n is the number of the plurality of assembled battery circuits.

4. A method for diagnosing a stuck battery according to claim 1 or 2, wherein the first diagnostic step is performed for each of the first to nth relay connection lines among the plurality of connection lines, and the method for diagnosing a stuck battery is further characterized by the step of turning on all of the charging relays and all of the negative electrode relays and charging the capacitor to full charge when it is diagnosed that a relay is stuck off in the nth relay connection line, where n is the number of the plurality of assembled battery circuits.

5. A method for diagnosing a stuck state as claimed in claim 2, further comprising a step of limiting the input / output values ​​of the battery pack to a predetermined input / output upper limit value or less until the first diagnosis by the second diagnostic step after the vehicle is started is completed, the input / output upper limit value being lower than the maximum input / output value of a component on the circuit.

6. A method for diagnosing a stuck state according to claim 2 or 5, wherein the input / output values ​​of the battery pack are limited depending on the number of circuits in the battery pack circuit that include a relay determined to be stuck off in the second diagnostic step.

7. A sticking diagnostic device for a relay included in a power supply circuit mounted on a vehicle, wherein the power supply circuit comprises: a battery pack parallel circuit in which battery pack 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 battery pack parallel circuit; a battery pack electrically connected to the battery pack circuit and the capacitor; and a controller that switches the positive relay, the negative relay, and the charging relay on and off; the battery pack circuit connects the positive relay in parallel to a series circuit that connects the charging relay and the charging resistor in series, and includes a relay connection line that electrically connects the charging relay and the negative relay in series; the controller charges the capacitor for each of a plurality of relay connection lines included in a plurality of the battery pack circuits, with the charging relay and the negative relay turned on; and the sticking diagnostic device diagnoses whether the charging relay and the negative relay are stuck off depending on the charge state of the capacitor.

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