System Main Relay Welding Check Method

Abstract

This invention provides a system main relay welding check method that can prevent the auxiliary battery from being drained when performing a welding check on the system main relay after the vehicle's main switch has been turned OFF. [Solution] A method for checking the welding of a system main relay provided between a high-voltage battery mounted on a vehicle and one or more auxiliary loads, comprising the steps of: stopping the power supply from the high-voltage battery to the auxiliary load after the vehicle is ready-off; performing a welding check of the system main relay after stopping the power supply to the auxiliary load; and, if the welding check shows that the system main relay is not welded, starting the power supply to the auxiliary load in response to a request from the auxiliary load.

Description

Technical Field

[0001] The present disclosure relates to a method for checking the presence or absence of welding of a system main relay provided between a high-voltage battery mounted on a vehicle and one or more auxiliary loads.

Background Art

[0002] Patent Document 1 discloses a method of supplying power from a high-voltage battery to a specific auxiliary load while maintaining the system main relay in the ON state when the main switch of the vehicle is turned off while the system main relay is ON and there is a specific auxiliary load (auxiliary battery as the main power source) that operates after the main switch is turned off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The OBD (On-Board Diagnostics) regulations require checking the presence or absence of welding of the system main relay at a specified monitor rate.

[0005] In the technique described in Patent Document 1 above, when there is a specific auxiliary load that operates after the main switch is turned off, the system main relay is maintained in the ON state, so it is impossible to perform a welding check of the system main relay. Therefore, as a countermeasure to satisfy the requirements of the OBD regulations, it is conceivable to forcibly stop the power supply from the high-voltage battery to the specific auxiliary load after the main switch is turned off and perform a welding check of the system main relay.

[0006] However, while the power supply from the high-voltage battery to a specific auxiliary load is stopped, the power from the auxiliary battery is consumed solely by the operation of that auxiliary load, which could lead to the auxiliary battery running out.

[0007] This disclosure was made in view of the above-mentioned problems, and aims to provide a system main relay welding check method that can prevent the auxiliary battery from being drained when the welding check of the system main relay is performed after the vehicle's main switch is turned OFF. [Means for solving the problem]

[0008] To solve the above problems, one aspect of the disclosed technology is a method for checking the welding of a system main relay provided between a high-voltage battery mounted on a vehicle and one or more auxiliary loads, the method comprising: stopping the power supply from the high-voltage battery to the auxiliary load after the vehicle is ready-off; performing a welding check of the system main relay after stopping the power supply to the auxiliary load; and, if the welding check shows that the system main relay is not welded, starting the power supply to the auxiliary load in response to a request from the auxiliary load. [Effects of the Invention]

[0009] According to the system main relay welding check method described above, when the welding check of the system main relay is performed after the vehicle's main switch is turned OFF, it is possible to prevent the auxiliary battery from running out. [Brief explanation of the drawing]

[0010] [Figure 1] Functional block diagram of a control unit and its peripheral parts for realizing a system main relay welding check method according to one embodiment of the present disclosure. [Figure 2A] Process flowchart illustrating a system main relay welding check method according to one embodiment of this disclosure. [Figure 2B] Process flowchart illustrating a system main relay welding check method according to one embodiment of this disclosure. [Figure 3] Example timing chart when IGB-ON requests are made due to other factors. [Figure 4] Example timing chart when there are no IGB-ON requests due to other factors. [Modes for carrying out the invention]

[0011] The system main relay welding check method disclosed herein, when stopping the power supply from the high-voltage battery to the auxiliary load after the vehicle is turned off in order to perform a welding check of the system main relay, treats this stoppage as temporary and promptly resumes power supply from the high-voltage battery to the auxiliary load after the welding check. This suppresses the draining of the auxiliary battery. Hereinafter, one embodiment of this disclosure will be described in detail with reference to the drawings.

[0012] <Embodiment> [composition] Figure 1 is a functional block diagram of a control unit 60 and its surrounding components for realizing a system main relay welding check method according to one embodiment of the present disclosure. The functional block illustrated in Figure 1 includes a high-voltage battery 10, a system main relay (SMR) 20, a DC-DC converter (DDC) 30, an auxiliary battery 40, a plurality of auxiliary loads 51 and 52, and the control unit 60. In Figure 1, power signal lines are shown as solid lines, and control / communication signal lines are shown as dotted lines.

[0013] This system main relay welding check method can be installed in vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs) that use electric motors as a power source.

[0014] The high-voltage battery 10 is a rechargeable secondary battery, such as a lithium-ion battery, and is a so-called drive battery that mainly supplies power to a starter motor, a traction motor, etc. (not shown). This high-voltage battery 10 can supply power to auxiliary loads 51 and 52 via the system main relay 20 and the DC-DC converter 30.

[0015] The system main relay 20 is a switching element for controlling the power transfer state of the high-voltage battery 10 and is installed between the high-voltage battery 10 and the DC-DC converter 30. An example of the system main relay 20 is a mechanical relay having movable terminals and fixed terminals. This system main relay 20 can switch between a state in which the input / output terminals are electrically connected (relay ON) and a state in which the input / output terminals are electrically disconnected (relay OFF) based on instructions from the control unit 60.

[0016] The DC-DC converter 30 is a power converter that can convert input power into power of a predetermined voltage and output it. One end of the DC-DC converter 30 is connected to the high-voltage battery 10 via the system main relay 20, and the other end is connected to the auxiliary battery 40, auxiliary load 51, and auxiliary load 52. The DC-DC converter 30 can supply the power output by the high-voltage battery 10 connected to one end to the auxiliary battery 40, auxiliary load 51, and auxiliary load 52 connected to the other end. The operation of the DC-DC converter 30 is controlled by the control unit 60.

[0017] The auxiliary battery 40 is a rechargeable secondary battery, such as a lead-acid battery or a lithium-ion battery, that supplies power to multiple auxiliary loads 51 and 52. This auxiliary battery 40 is connected to the DC-DC converter 30 so that it can be charged by the power of the high-voltage battery 10. Generally, the auxiliary battery 40 has a lower rated voltage than the high-voltage battery 10.

[0018] Auxiliary loads 51 and 52 are devices mounted on the vehicle, such as devices and equipment that consume electric power necessary to perform predetermined operations. The auxiliary loads 51 and 52 include specific auxiliary loads (for example, in-vehicle devices such as a drive recorder with a parking monitoring function) that consume electric power when the vehicle's power system is stopped (Ready-OFF), such as when parked. The auxiliary loads 51 and 52 operate with electric power supplied from the high-voltage battery 10 via the system main relay 20 and the DCDC converter 30, and electric power stored in the auxiliary battery 40. Note that in FIG. 1, an example in which two auxiliary loads 51 and 52 are mounted on the vehicle is shown, but the number of auxiliary loads mounted on the vehicle is not limited to this.

[0019] The control unit 60 is configured to control the ON / OFF operation of the system main relay 20 to control the power supply from the high-voltage battery 10 to the auxiliary battery 40 and the auxiliary loads 51 and 52. This control unit 60 includes at least each function of "IGSW control" for controlling the ON / OFF state of the IGB, "auxiliary power supply control" for supplying power to a specific auxiliary load during Ready-OFF, "auxiliary load control" for controlling the auxiliary loads 51 and 52, "power supply control" for controlling the supply of startup power to the DCDC converter 30, "system control" for controlling the power supply from the high-voltage battery 10 to the auxiliary loads 51 and 52 through the DCDC converter 30, and "SMR welding check" for determining whether or not the movable terminal and the fixed terminal of the system main relay 20 are in a welded state. These functions are communicably connected via a network such as CAN (Controller Area Network).

[0020] Part or all of this control unit 60 can typically be constituted by an electronic control unit (ECU: Electronic Control Unit) including a processor such as a microcomputer, a memory, and an input / output interface. As an example, each of the functions of IGSW control, auxiliary power supply control, and auxiliary load control described above can be included in the extended body ECU, and each of the functions of power supply control, system control, and SMR welding check can be included in the HV-ECU. This electronic control device can realize part or all of the functions described above by the processor reading and executing a program stored in the memory.

[0021] [Control] Next, referring further to FIGS. 2A and 2B, a system main relay welding check method according to this embodiment will be described. FIGS. 2A and 2B are flowcharts showing the processing procedures of the SMR welding check executed by the control unit 60. The processing in FIG. 2A and the processing in FIG. 2B are respectively connected by connectors X, Y, and Z.

[0022] The SMR welding check shown in FIGS. 2A and 2B is started when the ignition switch is turned off and the vehicle is in the Ready-OFF state. [[ID=!2]]

[0023] (Step S201) The control unit 60 determines whether it is necessary to perform a welding check on the system main relay 20. This determination can be made, for example, based on whether a state where the welding check of the system main relay 20 cannot be performed continues for a predetermined period due to a specific auxiliary load operating after the vehicle is in Ready-OFF. The predetermined period is set based on the requirements specified by the OBD regulations. The necessity of this welding check of the system main relay 20 is determined, for example, by the HV-ECU (SMR welding check function).

[0024] When the control unit 60 determines that a welding check of the system main relay 20 is necessary (Yes in step S201), the process proceeds to step S202. On the other hand, if the control unit 60 determines that a welding check of the system main relay 20 is unnecessary (step S201, No), the process proceeds to step S213.

[0025] (Step S202) The control unit 60 performs a process to temporarily suspend the auxiliary power supply control, or in other words, a process to turn off the request for auxiliary power supply control. A concrete example of this process is that the HV-ECU (system control function) first sends a signal to the expansion body ECU (auxiliary power supply control function) requesting a "temporary suspension of the auxiliary power supply control state," and upon receiving this signal, the expansion body ECU (auxiliary power supply control function) sends a signal to the HV-ECU (system control function) indicating "no request for auxiliary power supply control," and also sends a request to the expansion body ECU (IGSW control function) for "IGB-OFF due to auxiliary power supply control." In addition, the expansion body ECU disables sleep mode for CAN communication with the HV-ECU.

[0026] When the control unit 60 temporarily suspends the auxiliary power supply control, the process proceeds to step S203.

[0027] (Step S203) The control unit 60 performs IGB-OFF processing based on auxiliary power supply control. A concrete example of this processing is that the extended body ECU (IGSW control function), upon receiving a request for "IGB-OFF based on auxiliary power supply control," outputs an IGB-OFF signal to the HV-ECU (power supply control function). This process turns off the power to the DCDC converter 30, stopping the power supply from the high-voltage battery 10 to the auxiliary loads 51 and 52.

[0028] When the control unit 60 performs the IGB-OFF process by controlling the auxiliary power supply, the process proceeds to step S204.

[0029] (Step S204) The control unit 60 performs a welding check of the system main relay 20. This process is carried out by the HV-ECU (SMR welding check function). The welding check of the system main relay 20 can be performed using well-known methods such as monitoring the terminal voltage of the system main relay 20 by applying voltage fluctuation processing.

[0030] Once the control unit 60 performs a welding check on the system main relay 20, the process proceeds to step S205.

[0031] (Step S205) The control unit 60 determines whether or not welding has occurred in the system main relay 20. This determination is made by the HV-ECU (SMR welding check function). For example, if the terminal voltages of both terminals of the system main relay 20 are the same despite the voltage fluctuation, it can be determined that the fixed terminal (one or both of the positive and negative sides) and the movable terminal are welded together.

[0032] If the control unit 60 determines that no welding has occurred on the system main relay 20 (step S205, none), the process proceeds to step S206. On the other hand, if the control unit 60 determines that welding has occurred on the system main relay 20 (step S205, present), this SMR welding check is terminated.

[0033] (Step S206) The control unit 60 determines the result of the auxiliary power supply control feasibility determination. This auxiliary power supply control feasibility determination determines whether power can be started (startable) or not (cannot start) to a specific auxiliary load (such as a drive recorder) from the high-voltage battery 10. This determination is made based on the result of the auxiliary power supply control feasibility determination shown before IGB-OFF is performed by the auxiliary power supply control in step S203 above. The result of this auxiliary power supply control feasibility determination is received from the HV-ECU (system control) by the extended body ECU (auxiliary power supply control function) after the auxiliary power supply control state is temporarily suspended.

[0034] If the control unit 60 determines that the auxiliary power supply control can be started (step S206, start possible), the process proceeds to step S208. On the other hand, if the control unit 60 determines that the auxiliary power supply control cannot be started (step S206, cannot be started), the SMR welding check is terminated. In this case, the extended body ECU (auxiliary power supply control function) remains requesting the extended body ECU (IGSW control function) to perform "IGB-OFF due to auxiliary power supply control," and the CAN communication is set to sleep enabled. In addition, the "request for auxiliary power supply control" that was displayed before the IGB-OFF due to auxiliary power supply control was performed is discarded. Alternatively, if the control unit 60 determines that it has not received the result of the auxiliary power supply control feasibility determination (step S206, not received), the process proceeds to step S207.

[0035] (Step S207) The control unit 60 determines whether or not 1 hour has elapsed since the IGB-OFF was performed by the auxiliary power supply control in step S203. This determination is made to determine whether or not to maintain the temporarily suspended auxiliary power supply control in its current state if the result of the auxiliary power supply control feasibility determination has not been received. The 1 hour can be set arbitrarily and can be set to, for example, 35 seconds.

[0036] If the control unit 60 determines that one hour has elapsed since the IGB-OFF was performed by the auxiliary power supply control (step S207, yes), this SMR welding check is terminated. In this case, the extended body ECU (auxiliary power supply control function) remains requesting the extended body ECU (IGSW control function) to perform "IGB-OFF by auxiliary power supply control," and CAN communication is set to sleep enabled. In addition, the "request for auxiliary power supply control" that was displayed before the IGB-OFF by auxiliary power supply control was performed is discarded. Furthermore, auxiliary power supply control for specific auxiliary loads is prohibited until the next Ready-ON. On the other hand, if the control unit 60 determines that 1 hour has not elapsed since the IGB-OFF was performed by the auxiliary power supply control (step S207, no), the process proceeds to step S206.

[0037] (Step S208) The control unit 60 determines whether or not there is an IGB-ON request due to other factors. This IGB-ON request due to other factors refers to an IGB-ON request for auxiliary power supply control due to an auxiliary load other than a specific auxiliary load (e.g., air conditioning, battery, charging, etc.), rather than an IGB-ON request for auxiliary power supply control due to a specific auxiliary load. This IGB-ON request due to other factors is received by the extended body ECU (IGSW control function).

[0038] If the control unit 60 determines that there is an IGB-ON request due to other factors (step S208, yes), the process proceeds to step S209. On the other hand, if the control unit 60 determines that there are no IGB-ON requests due to other factors (step S208, none), the process proceeds to step S210.

[0039] (Step S209) The control unit 60 determines whether or not it has detected that the status of the auxiliary power supply control is undetermined. This auxiliary power supply control status = undetermined can be received from the HV-ECU (system control function) by the extended body ECU (auxiliary power supply control function) after the auxiliary power supply control status has been temporarily suspended. Figure 3 shows the status of each control and request in the case of an IGB-ON request due to other factors in a timing chart.

[0040] If the control unit 60 detects that the status of the auxiliary power supply control is undetermined (step S209, yes), the process proceeds to step S211. On the other hand, if the control unit 60 does not detect that the status of the auxiliary power supply control is undetermined (step S209, no), this SMR welding check is terminated.

[0041] (Step S210) The control unit 60 determines whether or not it has detected that CAN communication between the expansion body ECU and the HV-ECU has been interrupted for two hours or more. This second hour can be set to any time necessary to determine the communication interruption, for example, it can be 1 second. Figure 4 shows the status of each control and request in a timing chart when there are no IGB-ON requests due to other factors.

[0042] If the control unit 60 detects a communication interruption between the expanded body ECU and the HV-ECU for two hours or more (step S210, yes), the process proceeds to step S211. On the other hand, if the control unit 60 has not detected a communication interruption between the extended body ECU and the HV-ECU for two hours or more (step S210, no), this SMR welding check is terminated.

[0043] (Step S211) The control unit 60 performs IGB-ON processing based on auxiliary power supply control. A concrete example of this processing is that the extended body ECU (auxiliary power supply control function) sends a request for "IGB-ON based on auxiliary power supply control" to the extended body ECU (IGSW control function).

[0044] When the control unit 60 performs the IGB-ON process by controlling the supply of auxiliary power, the process proceeds to step S212.

[0045] (Step S212) The control unit 60 performs a process to restore the auxiliary power supply control state from a temporary suspension. A concrete example of this process is that the extended body ECU (auxiliary power supply control function) restores the "request for auxiliary power supply control" status, which was the result of the auxiliary power supply control feasibility determination shown before the IGB-OFF was performed by the auxiliary power supply control, to ON (request ON).

[0046] When the control unit 60 performs the process of restoring the auxiliary power supply control from a temporary state, the process proceeds to step S213.

[0047] (Step S213) The control unit 60 performs auxiliary power supply control, supplying power from the high-voltage battery 10 to the auxiliary battery 40, auxiliary load 51, and auxiliary load 52 via the system main relay 20 and the DC-DC converter 30. This control is performed by the extended body ECU (auxiliary power supply control function).

[0048] When the control unit 60 performs auxiliary power supply control, this SMR welding check is completed.

[0049] <Effects and Actions> As described above, according to the system main relay welding check method according to one embodiment of the present disclosure, when determining whether or not welding has occurred in a system main relay 20 provided between a high-voltage battery 10 mounted on a vehicle and one or more auxiliary loads 51 and 52, the power supply from the high-voltage battery 10 to the auxiliary loads 51 and 52 is temporarily stopped after the vehicle is turned Ready-OFF, and then a welding check of the system main relay 20 is performed. If the welding check shows that there is no welding in the system main relay 20, the power supply to the auxiliary loads 51 and 52 is promptly resumed upon request.

[0050] This method prevents the auxiliary battery 40 from draining while the welding check of the system main relay 20 is being performed after the vehicle has been turned Ready-OFF.

[0051] Although one embodiment of the present disclosure has been described above, the present disclosure can be understood not only as a system main relay welding check method, but also as a control unit for performing this method, a program for performing this method, a computer-readable non-temporary recording medium storing the program, a vehicle equipped with the control unit, etc. [Industrial applicability]

[0052] The method disclosed herein can be used, for example, when it is desirable to suppress the drain of the auxiliary battery when performing a welding check on the system's main relay. [Explanation of symbols]

[0053] 10 High-voltage batteries 20 System Main Relay (SMR) 30 DC-DC Converters (DDC) 40 Auxiliary battery 51, 52 Auxiliary load 60 control units

Claims

1. A method for checking the welding of a system main relay installed between a high-voltage battery mounted on a vehicle and one or more auxiliary loads, After the vehicle is ready-off, the power supply from the high-voltage battery to the auxiliary load is stopped. The steps include: stopping the power supply to the auxiliary load and then performing a welding check on the system main relay; The process includes, if the welding check indicates that the system main relay is not welded, starting to supply power to the auxiliary load in response to a request from the auxiliary load, System main relay welding check method.

2. The step of stopping the power supply to the auxiliary load is to stop the power supply from the high-voltage battery to the auxiliary load if the operation of a specific auxiliary load after the vehicle is ready-off prevents the welding check of the system main relay from being performed continuously for a predetermined period. The method for checking the welding of the system main relay according to claim 1.

3. The aforementioned specific auxiliary load is a drive recorder that activates the parking surveillance function after the vehicle is Ready-OFF. The method for checking the welding of the system main relay according to claim 2.

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