JP2017208873A - On-vehicle battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle battery system that can determine presence of welding of each of a plurality relays even when the relays are provided on a path of an AC loop.SOLUTION: In a first welding determination step, connection commands are given to relays SMRB1, SMRG1, SMRB2, and SMRG2 of first and second battery modules 10A and 10B, and the command to the relay SMRG1 is switched to an interruption command. A welding determination portion, when a detected value VL by a voltage sensor 16 exceeds a prescribed threshold, determines that welding is present in the relay SMRG1. In a second welding determination step, the interruption command to the relay SMRG1 is maintained, the relays SMRB1, SMRG1, SMRB2 for which the commands are switched to interruption commands are changed sequentially. When AC currents are outputted from an AC power source 34 and amplitude of AC currents detected by a current sensor 36 exceeds a prescribed threshold, the welding determination portion determines that welding is present in the relays for which the commands are switched to the interruption commands.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-vehicle battery system that determines the presence or absence of welding of a relay provided in a battery unit.

  A hybrid vehicle or electric vehicle using a rotating electrical machine as a drive source is equipped with a battery unit as a power source. In addition to the battery body, the battery unit is provided with a relay called a system main relay that switches between conduction and interruption between the battery body and the load. The system main relay is provided on each of the positive electrode line and the negative electrode line.

  When the system main relay is switched on / off (connected / disconnected), an arc may occur between the movable contact and the fixed contact, and the two contacts may be welded. Therefore, a determination system for determining whether or not the system main relay is welded is conventionally provided in the in-vehicle battery system.

  For example, in Patent Document 1, as shown in FIG. 8, a main battery 100 (DC power supply), a load 102, and a high voltage provided with system main relays SMRB and SMRG respectively provided on a positive electrode line and a negative electrode line connecting both of them. A welding determination unit 104 is connected to the circuit. The welding determination unit 104 includes an AC power source 106, one end of which is connected to the high voltage circuit, and the other end is grounded to the vehicle body 108 (body).

  In determining whether the system main relays SMRB, SMRG are welded or not, first, an OFF command (shut-off command) is given to both relays SMRB, SMRG. Thereafter, an alternating current is output from the alternating current power source 106. At this time, when the system main relay SMRB on the positive electrode side is welded, an AC loop L1 is formed by the AC current flowing from the AC power source 106 as shown in FIG. Further, when the negative-side system main relay SMRG is welded, an AC loop L2 is formed by the AC current flowing from the AC power source 106. A broken line between the load 102 and the vehicle body 108 represents capacitive coupling.

  On the other hand, if welding has not occurred on both the positive and negative system main relays SMRB and SMRG (when the movable contact and the fixed contact can be separated), an AC loop is provided by giving a shutoff command to both relays SMRB and SMRG. L1 and AC loop L2 are broken. To be precise, a capacitive coupling is formed between the movable contact and the fixed contact of the relay, but the current amplitude of the AC loops L1 and L2 is reduced as compared with that during welding due to the impedance derived from the capacitive coupling. Welding determination unit 104 determines whether system main relays SMRB and SMRG are welded based on the presence / absence of AC loops L1 and L2 and the amplitude comparison.

Japanese Patent Laying-Open No. 2015-35708

  By the way, in recent years, there are cases where the battery unit is divided (divided) into a plurality of battery modules and these are connected in series so that the battery can be arranged in a slight gap of the vehicle. Assuming that the battery module is used alone, a system main relay is provided on each of the positive line and the negative line of each battery module.

  As shown in FIG. 9, when a plurality (for example, two) of battery modules 110A and 110B are connected in series, a plurality (for example, three) of system main relays SMRB1, SMRG2, SMBG2, and the like on the path of the positive-side AC loop L10. SMRB2 is provided. Then, even if welding occurs in one of them (for example, SMRG2), since the other two (for example, SMRB1, SMRB2) are not welded, a shut-off command is given to the system main relays SMRB1, SMRG2, SMRB2 At that time, the AC loop L10 is broken. As a result, it becomes difficult to detect the occurrence of welding of system main relay SMRG2.

  Therefore, an object of the present invention is to provide an in-vehicle battery system capable of determining whether or not each system main relay is welded when a plurality of system main relays are provided on an AC loop path.

  The present invention relates to an in-vehicle battery system. The system includes a battery and a first battery module including a relay provided on each of a positive electrode side and a negative electrode side of the battery, a battery and a relay provided on each of a positive electrode side and a negative electrode side of the battery, A second battery module connected in series to the positive side of the battery module; a voltage sensor for detecting a voltage between the negative line drawn from the first battery module and the positive line drawn from the second battery module; An AC power source having one end connected between the positive electrode side relay and the negative electrode side relay of the first battery module and the other end grounded to a vehicle body, and a current sensor that detects a current flowing through the AC power source. The positive electrode side and the negative electrode of the welding determination unit and the first and second battery modules, respectively. And a control unit for switching the connection and disconnection of the relay. The control unit is configured to connect only the negative relay of the first battery module from a state where the connection command is given to the positive and negative relays of the first and second battery modules. The first welding determination step for switching from to the disconnection command and maintaining the connection command for other relays can be executed. Further, the positive-side relay of the first battery module, and the second battery module, in which a command to be given to the negative-side relay of the first battery module is maintained as a cutoff command and a connection command is given The second welding determination step of sequentially changing the relays to be switched from the connection command to the disconnection command can be executed for the positive and negative relays. The welding determination unit determines that welding is present in the negative relay of the first battery module when a detection value of the voltage sensor exceeds a predetermined threshold during an execution period of the first welding determination step. In addition, when an AC current is output from the AC power source during an execution period of the second welding determination step, and the amplitude of the AC current detected by the current sensor exceeds a predetermined threshold, when the threshold is exceeded, It is determined that there is welding for the relay that is the target of switching from the connection command to the disconnection command.

  According to the present invention, it is possible to determine whether or not individual system main relays are welded even when a plurality of system main relays are provided on the AC loop path.

It is a circuit diagram which illustrates the vehicle-mounted battery system which concerns on this embodiment. It is a figure which illustrates the welding determination flow (SMRG1 welding presence determination) based on this embodiment. It is a figure which illustrates the welding determination flow (SMRB2 welding presence determination) based on this embodiment. It is a figure which illustrates the welding determination flow (SMRG2 welding presence determination) based on this embodiment. It is a figure which illustrates the welding determination flow (SMRB1 welding presence determination) based on this embodiment. It is a flowchart (1/2) which illustrates the welding determination flow concerning this embodiment. It is a flowchart (2/2) which illustrates the welding determination flow concerning this embodiment. It is a figure explaining the conventional welding determination. It is a figure explaining the conventional welding determination.

<Overall configuration>
FIG. 1 illustrates a circuit diagram of an in-vehicle battery system according to the present embodiment. Arrow lines indicate signal lines. The in-vehicle battery system is mounted on a hybrid vehicle or an electric vehicle using, for example, a rotating electric machine as a drive source. The in-vehicle battery system includes battery modules 10 </ b> A and 10 </ b> B, a welding determination unit 12, a control unit 14, and a voltage sensor 16.

  The battery module 10A (first battery module) includes a battery 18A, a system main relay SMRB1 (positive relay) provided on the positive electrode side of the battery 18A, and a system main relay SMRG1 (provided on the negative electrode side of the battery 18A). Negative electrode side relay).

  Similarly, the battery module 10B (second battery module) includes a battery 18B, a system main relay SMRB2 (positive relay) provided on the positive side of the battery 18B, and a system provided on the negative side of the battery 18B. A main relay SMRG2 (negative electrode side relay) is provided.

  In FIG. 1, two battery modules are connected in series so that the battery module 10A is on the negative electrode side and the battery module 10B is on the positive electrode side. Specifically, the positive electrode wire 20 drawn from the system main relay SMRB1 of the battery module 10A and the negative electrode wire 22 drawn from the system main relay SMRG2 of the battery module 10B are connected.

  Both the batteries 18A and 18B are configured by connecting a plurality of cylindrical batteries made of secondary batteries such as nickel metal hydride batteries and lithium ion batteries. For example, about 5 groups in which about 5 to 10 cylindrical batteries are connected in parallel are provided, and the respective batteries 18A and 18B are configured by connecting the groups in series.

  System main relays SMRB1, SMRG1, SMRB2, and SMRG2 switch between conduction / interruption of batteries 18A and 18B and the load, respectively. In principle, it is sufficient to provide a system main relay on the negative electrode line 24 of the negative battery module 10A and the positive electrode line 26 of the positive battery module 10B, but the battery modules 10A and 10B can be used alone. In consideration of the expandability of the battery module, each of the battery modules 10A and 10B is provided with a positive system main relay SMRB and a negative system main relay SMRG.

  Voltage sensor 16 detects voltage VL between negative electrode line 24 drawn from system main relay SMRG1 of battery module 10A and positive line 26 drawn from system main relay SMRB2 of battery module 10B. Further, a smoothing capacitor CL is provided in parallel with the voltage sensor 16 in order to smooth (absorb) voltage fluctuations of the batteries 18A and 18B.

  When system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are all connected, the voltage between positive line 26 and negative line 24 becomes a power supply voltage that is the voltage sum of battery 18A and battery 18B. This power supply voltage is a reference value that determines the duty ratio of a DC / DC converter described later.

  When any one of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 is in a cut-off state, the voltage between the positive electrode line 26 and the negative electrode line 24 is reduced according to the discharge (discharge) of the charge accumulated in the smoothing capacitor CL. Finally, it reaches 0 [V]. As will be described later, the presence or absence of welding of system main relay SMRG1 is determined based on the voltage value detected by voltage sensor 16 after a predetermined charge discharge period.

  A power control unit 30 is connected to the tip of the voltage sensor 16. The power control unit 30 includes, for example, a DC / DC converter and an inverter (both not shown). The power control unit 30 boosts the DC voltage output from the battery modules 10A and 10B. The inverter also converts the DC power after boosting into AC power. The converted AC power is supplied to a load such as a rotating electric machine (not shown).

  Since the power control unit 30 is a high voltage device, it is insulated from the vehicle body 32 (body). For example, the power control unit 30 is fixed to the vehicle body 32 via an insulating material. As will be described later, when an alternating current is output from the alternating current power supply 34 of the welding determination unit 12, a capacitive coupling Cs (FIG. 3 and the like) is formed between the power control unit 30 and the vehicle body 32.

  Weld determination unit 12 determines whether system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are welded. The welding determination unit 12 includes an AC power supply 34, a current sensor 36, and a calculation unit 38.

  One end of AC power supply 34 is connected between system main relays SMRB1, SMRG1 of battery module 10A, and the other end is connected to vehicle body 32. In FIG. 1, one end of the AC power supply 34 is connected between the system main relay SMRG1 and the battery 18A, but one end of the AC power supply 34 may be connected between the battery 18A and the system main relay SMRB1. Further, when connecting to the battery module 10A, the AC power supply 34 and the battery module 10A may be connected via a coupling capacitor CC in order to prevent inflow of DC current and to enable supply of AC current. .

  The current sensor 36 detects an alternating current flowing through the alternating current power supply 34. The current sensor 36 is provided in a wiring between the AC power supply 34 and the vehicle body 32, for example.

  The arithmetic unit 38 is configured by a computer, for example, and includes a CPU that is an arithmetic circuit and a memory that is a storage device. The memory stores a program for executing a welding determination flow described later, a threshold value used in the determination flow, and the like.

  The calculation unit 38 acquires the AC current waveform detected by the current sensor 36 and the voltage value detected by the voltage sensor 16. Calculation unit 38 determines whether system main relays SMRB1, SMRG2, and SMRB2 are welded based on the amplitude of the alternating current acquired from current sensor 36. Further, based on the voltage value acquired from the voltage sensor 16, it is determined whether or not the system main relay SMRG1 is welded.

  The control unit 14 controls equipment in the vehicle including the battery system. The control unit 14 is configured by a computer, for example, and includes a CPU that is an arithmetic circuit and a memory that is a storage device. The memory includes a volatile memory such as an SRAM and a nonvolatile memory such as a ROM and a hard disk. The memory stores a program for executing a welding determination flow described later, a threshold value used in the determination flow, and the like.

  The control unit 14 receives detection values from various sensors mounted on the vehicle. Specifically, the voltage value VL between the positive electrode line 26 and the negative electrode line 24 is received from the voltage sensor 16, and the current value flowing (flowing) into the AC power supply 34 is received from the current sensor 36. In addition, the control unit 14 receives welding determination information from the calculation unit 38 of the welding determination unit 12.

  Moreover, the control part 14 controls the apparatus in a vehicle. For example, on / off control of the switching elements of the DC / DC converter in the power control unit 30 is performed based on a comparison between the low voltage side voltage VL acquired from the voltage sensor 16 and the high voltage side voltage VH (not shown).

  Control unit 14 controls connection / disconnection (on / off) of system main relays SMRB1, SMRG1, SMRB2, and SMRG2. Control unit 14 gives a connection command or a disconnection command to system main relays SMRB1, SMRG1, SMRB2, and SMRG2. For example, the connection command is a current signal for exciting the electromagnets in the system main relays SMRB1, SMRG1, SMRB2, and SMRG2. The cutoff command is, for example, cutoff of current supply to the electromagnet (I = 0 [A]).

  In addition, the control unit 14 transmits the connection / disconnection state of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 to the calculation unit 38 of the welding determination unit 12 in a welding determination flow described later. The calculation unit 38 performs welding determination according to the connection / disconnection state of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2.

<Welding determination flow>
2 to 5 exemplify respective welding determination steps of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 according to the present embodiment, and also include these steps in FIGS. A flowchart is illustrated. 2 to 5, signal lines (arrow lines) that are less relevant to each welding determination are omitted as appropriate.

  The welding determination flow according to the present embodiment is started with a Ready-Off operation of the vehicle as a trigger. The Ready-Off operation indicates an off operation with respect to the power switch of the vehicle, and is an operation for stopping the vehicle system. As a result of the Ready-Off operation, system main relays SMRB1, SMRG1, SMRB2, and SMRG2 that have been in the on state (connected state) are switched to the off state, and the batteries 18A and 18B are disconnected from the load. In the present embodiment, the welding determination flow is executed during a period in which the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are shifted from the on state to the off state.

  First, when the control unit 14 receives a Ready-Off operation, that is, when it detects that the power switch of the vehicle is turned off, the control unit 14 has given a connection command (on command) to the system main relays SMRB1, SMRG1, SMRB2, and SMRG2. From the connection command to only the system main relay SMRG1 is switched from the connection command to the disconnection command, and the first welding determination step is performed to maintain the connection command for the other system main relays SMRB1, SMRG1, and SMRB2. Step S10 in FIG. 6). Further, control unit 14 transmits the command (connection command / cutoff command) given to system main relays SMRB1, SMRG1, SMRB2, and SMRG2 to the calculation unit 38 of welding determination unit 12 by executing the first welding determination step. To do.

  The calculation unit 38 monitors the detection value of the voltage sensor 16 during the execution period of the first welding determination step. That is, the calculation unit 38 waits until the charge discharge period (discharge period) of the smoothing capacitor CL elapses (S12 in FIG. 6), and then whether or not the detection value VL to be monitored exceeds a predetermined threshold value Vth. Is determined (S14). The threshold value Vth is 0 [V], for example.

  When the detected value VL exceeds the threshold value Vth in step S14, the calculation unit 38 determines that the system main relay SMRG1 is welded (S16). The calculation unit 38 transmits the determination result to the control unit 14. In response to the determination result that there is welding, the control unit 14 outputs a warning to a display in the vehicle, a user terminal, or the like (S18). For example, a message that prompts inspection by a dealer is output.

  Further, the control unit 14 gives a cutoff command to all system main relays for which a connection command is currently given (S20), and stops the electric system of the vehicle (ends the flow).

  Returning to step S14, when the detection value VL is equal to or less than the threshold value Vth, the calculation unit 38 determines that the system main relay SMRG1 is not welded (S22). The determination result is transmitted to the control unit 14.

  Upon receiving the determination result that the system main relay SMRG1 is not welded, the control unit 14 executes a second welding determination step for switching the system main relay to be subjected to welding determination. That is, the control unit 14 maintains the cutoff command for the system main relay SMRG1 to which the cutoff command is given. Further, the system main relays to be switched from the connection command to the cutoff command are sequentially changed with respect to the system main relays SMRB1, SMRB2, and SMRG2 to which the connection command is given in the first welding step (FIGS. 3 to 5, (S24, S34, S44 in FIG. 6).

  In the flow shown in FIG. 6, the control unit 14 switches the connection command to the cutoff command for the system main relay SMRB2. A connection command is maintained for system main relays SMRB1 and SMRG2, and a disconnection command is maintained for system main relay SMRG1 (S24 in FIGS. 3 and 6). The control unit 14 transmits the command content to each system main relay to the calculation unit 38.

  In response to this, the calculation unit 38 outputs an alternating current from the alternating current power supply 34 (S26). If welding has occurred in the system main relay SMRB2, an AC loop L20 as shown in FIG. 3 is formed. That is, AC power supply 34 → coupling capacitor CC → battery 18A → system main relay SMRB1 (connected) → system main relay SMRG2 (connected) → battery 18B → system main relay SMRB2 (welding) → power control unit 30 → capacitive coupling An AC loop L20 with Cs (floating capacitance) → vehicle body 32 → AC power supply 34 is formed.

  At this time, the current sensor 36 detects an alternating current flowing through the alternating current loop L20. The calculation unit 38 refers to the amplitude (crest value) of the alternating current detected by the current sensor 36, and determines whether or not the amplitude A exceeds a predetermined threshold Ath (S28). When it exceeds, the calculating part 38 determines with welding to the system main relay SMRB2 which was the switching target from the connection command to the cutoff command at the time of the excess (S30). This determination result is transmitted to the control unit 14. The control unit 14 executes step S18 (warning output) and step S20 (relay cutoff) described above, and ends the flow.

  In step S28, when the amplitude A of the alternating current is equal to or smaller than the predetermined threshold Ath, the arithmetic unit 38 determines that the system main relay SMRB2 is not welded (S32). The determination result is sent to the control unit 14.

  Upon receiving the determination result that the system main relay SMRB2 is not welded, the control unit 14 switches the system main relay to be subjected to welding determination to SMRG2. Control unit 14 maintains the cutoff command for system main relay SMRG1 to which the cutoff command is given. Further, the connection command is maintained for system main relay SMRB1 to which the connection command is given. Further, for the system main relay SMRB2 once given a disconnection command, the disconnection command is switched to the connection command, and for the system main relay SMRG2 given a connection command, the connection command is switched to the disconnection command ( S34 in FIG. 4 and FIG. The control unit 14 transmits the command content to each system main relay to the calculation unit 38.

  The calculation unit 38 receives this and outputs an alternating current from the alternating current power supply 34 (S36). If welding has occurred in the system main relay SMRG2, an AC loop L20 similar to that in FIG. 3 is formed.

  At this time, the current sensor 36 detects an alternating current flowing through the alternating current loop L20. The calculation unit 38 refers to the amplitude of the alternating current detected by the current sensor 36 and determines whether or not the amplitude A exceeds a predetermined threshold Ath (S38). If it exceeds, the calculation unit 38 determines that the system main relay SMRG2 is welded (S40). This determination result is transmitted to the control unit 14. The control unit 14 executes step S18 (warning output) and step S20 (relay cutoff) described above, and ends the flow.

  In step S38, when the amplitude A of the alternating current is equal to or smaller than the predetermined threshold Ath, the calculation unit 38 determines that the system main relay SMRG2 is not welded (S42). The determination result is sent to the control unit 14.

  Upon receiving the determination result that the system main relay SMRG2 is not welded, the control unit 14 switches the system main relay to be subjected to welding determination to SMRB1. Control unit 14 maintains the cutoff command for system main relay SMRG1 to which the cutoff command is given. Further, the connection command is maintained for system main relay SMRB2 to which the connection command is given. Further, for the system main relay SMRG2 to which the disconnection command is once given, the cutoff command is switched to the connection command, and for the system main relay SMRB1 to which the connection command is given, the connection command is switched to the cutoff command ( S44 in FIGS. 5 and 7). The control unit 14 transmits the command content to each system main relay to the calculation unit 38.

  The calculation unit 38 receives this and outputs an alternating current from the alternating current power supply 34 (S46). If welding has occurred in the system main relay SMRB1, an AC loop L20 similar to that in FIG. 3 is formed.

  At this time, the current sensor 36 detects an alternating current flowing through the alternating current loop L20. The computing unit 38 refers to the amplitude of the alternating current detected by the current sensor 36 and determines whether or not the amplitude A exceeds a predetermined threshold Ath (S48). When it exceeds, the calculating part 38 determines with welding to the system main relay SMRB1 (S50). This determination result is transmitted to the control unit 14. The control unit 14 executes step S18 (warning output) and step S20 (relay cutoff) described above, and ends the flow.

  In step S48, when the amplitude A of the alternating current is equal to or smaller than the predetermined threshold Ath, the calculation unit 38 determines that the system main relay SMRB1 is not welded (S52). The determination result is sent to the control unit 14.

  In step S52, in response to the determination result indicating that no system main relay SMRB1 is welded, that is, no system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are welded, the control unit 14 is currently connected. The system main relay that is in the state is switched to the cutoff state. That is, a cutoff command is given to system main relays SMRB2 and SMRG2 (S54). All system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are cut off, and the electric system of the vehicle is stopped.

  By performing the above welding determination flow, it is possible to determine whether or not all the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are welded. In addition, in the welding determination flow according to the present embodiment, the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 are controlled to be connected / disconnected (ON / OFF) and the deterioration of each system main relay is suppressed. doing.

  As described above, when the system main relay is connected / disconnected, the distance between the fixed contact and the movable contact becomes shorter than the insulation distance, and an arc is generated. Also, with the aim of shortening the arc generation period, that is, shortening the period in which the distance between the fixed contact and the movable contact is shorter than the insulation distance, the movable contact was given a predetermined biasing force when connected. It is made to collide with a fixed contact in a state. Due to this collision, the movable contact and the fixed contact are worn. In this way, the contact deterioration (welding and wear) of the system main relay progresses as the number of connection / disconnection increases.

  In the present embodiment, when performing the welding determination flow, the number of switching of the connection / disconnection of the system main relay is suppressed, and the contact deterioration of the system main relay accompanying the connection / disconnection switching as described above is suppressed. .

Specifically, referring to the flow in FIG. 6 and FIG. 7, the number of switching of connection / disconnection of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2 is as follows.
SMRB1: Connect → Block: 1 time, Block → Connect: 0 times SMRG1: Connect → Block: 1 time, Block → Connect: 0 times SMRB2: Connect → Block: 2 times, Block → Connect: 1 time SMRG2: Connect → Block : 2 times, blocking → connection: 1 time.

  In particular, in the former two system main relays SMRB1 and SMRG1, in the welding determination flow, switching from connection to disconnection is limited to one time, and switching from disconnection to connection is 0. This is the same as the operation performed when the electric system of the vehicle changes from the start state to the stop state in response to the Ready-Off command. That is, in the welding determination flow according to the present embodiment, the presence / absence of welding of the system main relays SMRB1, SMRG1 is determined without increasing the number of connection / blocking and blocking / connection operations from the normal Ready-Off process. .

  In the above example, among the three main system relays SMRB1, SMRB2, and SMRG2, the determination target of welding presence / absence is set so that the number of SMRG1 connection / disconnection switching is relatively small. It is not limited to form. That is, with reference to the welding determination flow of FIGS. 6 and 7, the connection / disconnection switching frequency of the three main system relays for which the presence or absence of welding is finally determined is relatively reduced. Based on this, the order of performing the welding determination of the system main relays SMRB1, SMRB2, and SMRG2 may be appropriately changed. For example, the determination order of the presence / absence of welding of the one having the highest possibility of welding among the three members, for example, the one having the highest temperature among the three main relays may be rotated last.

  Further, in the welding determination flow according to the present embodiment, as shown in step S20, whether or not welding is present is determined when it is determined that welding is present in any one of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2. Even if an undetermined system main relay remains, the welding determination flow is terminated in order to prevent a so-called accompanying failure.

  For example, when system main relays SMRG1 and SMRG2 are welded and the welding presence / absence determination is advanced thereafter, when switching system main relay SMRB2 from the disconnected state to the connected state in step S34, batteries 18A and 18B are electrically connected to the load. As a result, an inrush current may flow into the smoothing capacitor CL (cooperating failure). As in the welding determination flow according to the present embodiment, when it is determined that welding is present in any one of the system main relays SMRB1, SMRG1, SMRB2, and SMRG2, the welding determination flow is terminated. Along with the failure can be prevented.

  10A, 10B battery module, 12 welding determination unit, 14 control unit, 16 voltage sensor, 18A, 18B battery, 24 negative line, 26 positive line, 32 vehicle body, 34 AC power supply, 36 current sensor, 38 calculation unit, L20 AC loop , SMRB Positive system main relay, SMRG Negative system main relay.

Claims (1)

A first battery module including a battery and a relay provided on each of a positive electrode side and a negative electrode side of the battery;
A second battery module comprising a battery and a relay provided on each of the positive electrode side and the negative electrode side of the battery and connected in series to the positive electrode side of the first battery module;
A voltage sensor for detecting a voltage between the negative electrode line drawn from the first battery module and the positive electrode line drawn from the second battery module;
An AC power source having one end connected between the positive electrode side relay and the negative electrode side relay of the first battery module and the other end grounded to a vehicle body, and a current sensor for detecting a current flowing through the AC power source, A welding determination unit provided;
A controller that switches connection and disconnection of the positive and negative relays of the first and second battery modules, and
An in-vehicle battery system comprising:
The controller is
Switching from a connection command to a disconnection command for only the negative relay of the first battery module from a state where a connection command is given to the positive and negative relays of the first and second battery modules, respectively. A first welding determination step for maintaining a connection command for other relays;
The command given to the negative side relay of the first battery module is maintained as a cutoff command, and the positive side relay of the first battery module, to which the connection command is given, and the second battery module A second welding determination step for sequentially changing a relay to be switched from a connection command to a cutoff command for the positive electrode side and the negative electrode side relay;
Is possible and
The welding determination unit
When the detection value of the voltage sensor exceeds a predetermined threshold in the execution period of the first welding determination step, it is determined that the negative relay of the first battery module is welded,
When the second welding determination step is performed, an alternating current is output from the alternating current power source, and when the amplitude of the alternating current detected by the current sensor exceeds a predetermined threshold, the connection at the time when the threshold is exceeded It is determined that there is welding for the relay that is the target of switching from the command to the shut-off command.
An in-vehicle battery system characterized by the above.

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