Vehicle power system

Abstract

The present invention provides a vehicle power supply system. When a backup low-voltage power supply is in a state capable of supplying power to operate an important load in an emergency, the vehicle power supply system can output a signal indicating that the backup low-voltage power supply is in a state capable of supplying power to operate an important load in an emergency in a short period of time when the vehicle power supply system changes from an off state to an on state. The vehicle power supply system (1) includes a main power supply system (10) having a main low-voltage power supply (11) and a backup power supply system (20) having a backup low-voltage power supply (23). When the vehicle power supply system (1) is in an off state and the state of a vehicle (V) satisfies a specified condition, a backup power supply control device (25) of the backup power supply system (20) performs a backup low-voltage power supply state estimation process.

Description

Technical Field

[0001] The present invention relates to a vehicle power supply system mounted on a vehicle. Background Art

[0002] In recent years, efforts to improve traffic safety have been underway to make cities and human settlements inclusive, safe, resilient, and sustainable. For example, vehicles are required to maintain traffic safety even in the event of a vehicle malfunction.

[0003] Therefore, there is a known vehicle power supply system that can continue to supply power to specific important loads by supplying power from a backup power supply when an abnormality occurs in the main power supply, thereby ensuring traffic safety even when an abnormality occurs in the main power supply (for example, refer to patent document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-218013 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In the vehicle power supply system of Patent Document 1, in order to reliably supply power from the backup power supply to a specific critical load in the event of an abnormality in the main power supply, it is preferable to pre-estimate or detect whether the backup power supply is in a state of supplying power to the specific critical load. One method for pre-estimate or detect whether the backup power supply is in a state of supplying power to the specific critical load is to calculate the internal impedance of the backup power supply. However, in order to calculate the internal impedance of the backup power supply with the desired accuracy, it is necessary to measure the internal resistance value of the backup power supply for a predetermined time (e.g., approximately 5 to 10 minutes).

[0009] In this case, the estimation result or detection result of whether the backup power supply is supplying power to the specific essential load is not output from the time the vehicle power system transitions from the off state to the on state until the estimation process or detection process of whether the backup power supply is supplying power to the specific essential load is completed. Therefore, for example, in a vehicle capable of autonomous driving, there is a problem that even if the backup power supply is supplying power to the specific essential load, it is impossible to determine whether autonomous driving is possible and thus cannot be executed from the time the vehicle power system transitions from the off state to the on state until the estimation process or detection process of whether the backup power supply is supplying power to the specific essential load is completed.

[0010] The present invention provides a vehicle power supply system, which, when a backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency, when the vehicle power supply system changes from a closed state to an open state, the vehicle power supply system can output a signal indicating that the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency in a short period of time.

[0011] Means for solving problems

[0012] The present invention provides a vehicle power supply system mounted on a vehicle, comprising:

[0013] a main power system having a main low voltage power source and typical loads; and

[0014] A backup power supply system, which has a backup low-voltage power supply and important emergency loads, and is connected to the main power supply system, wherein:

[0015] The backup power supply system is capable of supplying power from the backup low-voltage power supply to the main power supply system.

[0016] The backup power system comprises:

[0017] a switching device capable of switching between a connected state and a disconnected state with the main power system, and

[0018] A backup power supply control device, which controls the switching device,

[0019] The backup power supply control device is capable of executing a backup low-voltage power supply state estimation process, wherein the backup low-voltage power supply state estimation process estimates whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important load.

[0020] The backup power supply control device can output a signal indicating whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important load based on the estimation result of the backup low-voltage power supply state estimation process.

[0021] The backup power supply control device executes the backup low-voltage power supply state estimation process when the vehicle power supply system is in the off state and the state of the vehicle satisfies a predetermined condition.

[0022] Effects of the Invention

[0023] According to the present invention, when the vehicle power supply system is in a closed state and the state of the vehicle meets the specified conditions, a backup low-voltage power supply state estimation process is performed to estimate whether the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency. Thus, when the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency, when the vehicle power supply system changes from a closed state to an open state, a signal indicating that the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency can be output in a short period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 FIG. 1 is a schematic diagram of a vehicle power supply system according to one embodiment of the present invention.

[0025] Figure 2 This is a flowchart (Part 1) showing an example of the operation of the vehicle power supply system when the vehicle power supply system is in the off state according to one embodiment of the present invention.

[0026] Figure 3 This is a flowchart (part 2) showing an example of the operation of the vehicle power supply system when the vehicle power supply system is in the off state according to one embodiment of the present invention.

[0027] Figure 4 This is a flowchart (Part 3) showing an example of the operation of the vehicle power supply system when the vehicle power supply system is in the off state according to one embodiment of the present invention.

[0028] Figure 5 This is a flowchart showing an example of the operation of the vehicle power supply system when the vehicle power supply system according to one embodiment of the present invention transitions from the off state to the on state.

[0029] Figure 6 This is a flowchart (part 1) showing an example of a standby low-voltage power supply state estimation process in a vehicle power supply system according to one embodiment of the present invention.

[0030] Figure 7 This is a flowchart (part 2) showing an example of a standby low-voltage power supply state estimation process in a vehicle power supply system according to one embodiment of the present invention.

[0031] Figure 8 This is a flowchart showing a modified example of the standby low-voltage power supply state estimation process in the vehicle power supply system according to one embodiment of the present invention.

[0032] Figure 9 This is a flowchart showing an example of the operation of the vehicle power supply system when an abnormality occurs in the main power supply system while the vehicle power supply system is in the ON state according to one embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1 Vehicle power system

[0035] 10 Main power system

[0036] 12 Normal load

[0037] 20 Backup power system

[0038] 22 Important loads in emergencies

[0039] 23 Backup low voltage power supply

[0040] 24 Switching device

[0041] 25 Backup power supply control device

[0042] 30 High voltage power supply system

[0043] 31 High-voltage power supply

[0044] 32 High voltage load

[0045] 40 Pressure reducing device

[0046] Q discharge capacity

[0047] Qset specified value

[0048] t Elapsed time

[0049] tset specified time

[0050] T temperature

[0051] T0 temperature

[0052] Tset specified value

[0053] ΔT temperature difference

[0054] V Vehicle. DETAILED DESCRIPTION

[0055] Hereinafter, one embodiment of a vehicle power supply system according to the present invention will be described with reference to the drawings.

[0056] [Overall structure of vehicle power supply system]

[0057] like Figure 1As shown, a vehicle power supply system 1 in this embodiment is mounted on a vehicle V. The vehicle power supply system 1 includes a main power supply system 10, a backup power supply system 20 connected to the main power supply system 10, a high-voltage power supply system 30, and a step-down device 40. The high-voltage power supply system 30 is connected to the main power supply system 10 and the backup power supply system 20 via a step-down device (DC / DC CONY) 40. The step-down device 40 steps down the voltage of the power flowing through the high-voltage power supply system 30. The step-down device 40 is, for example, a DC-DC converter.

[0058] A vehicle V equipped with a vehicle power supply system 1 is equipped with a drive unit 321 having a rotary electric machine MG, which will be described later, and a high-voltage power supply 31 that supplies power for driving the drive unit 321. Furthermore, the vehicle V is a vehicle that can be driven by the power of the rotary electric machine MG driven by the power of the high-voltage power supply 31. Furthermore, the vehicle V may also be equipped with an internal combustion engine. The internal combustion engine can function as a power source for driving the vehicle V, or as a power source for driving a generator (not shown). In other words, the vehicle V may be an electric vehicle without an internal combustion engine, or a hybrid vehicle with an internal combustion engine and a rotary electric machine MG for driving the vehicle. Furthermore, in this embodiment, the vehicle V is a vehicle that can be driven automatically under specific conditions.

[0059] <Main Power System>

[0060] The main power supply system 10 includes a main low-voltage power supply 11 and a normal load 12 .

[0061] The main low-voltage power supply 11 is, for example, a secondary battery such as a lithium-ion battery or a lead-acid battery, and outputs power at a voltage of, for example, 12 V.

[0062] The main low-voltage power supply 11 is provided on a connection line L11. One end of the connection line L11 is connected to a contact C11 formed on the connection line L10, and the other end is connected to a ground line having a reference potential in the vehicle power supply system 1. The positive side of the main low-voltage power supply 11 is connected to the contact C11 side of the connection line L11, and the negative side is connected to the ground line side of the connection line L11.

[0063] The normal loads 12 include loads that perform functions related to the driving operation, stopping operation, or driving control of the vehicle V. The normal loads 12 include an ECU (Electronic Control Unit) 50 capable of performing driving control of the vehicle V. Furthermore, the normal loads 12 may include at least one of auxiliary loads for braking the vehicle V, such as an automatic braking system, auxiliary loads for steering the vehicle V, such as an automatic steering system, auxiliary loads for acquiring external information about the vehicle V, such as a light detection and ranging (LiDAR) system, a wiper system, a power window system, and measuring instruments.

[0064] Normally, the load 12 is connected to one end of the connection line L10 .

[0065] <Backup Power System>

[0066] The backup power supply system 20 includes a backup power supply unit 21 and an emergency important load 22 .

[0067] The backup power supply unit 21 includes a backup low-voltage power supply 23 , a switching device 24 , and a backup power supply control device (BMS) 25 that controls the switching device 24 .

[0068] The backup power supply unit 21 includes a first external connection terminal T211, a second external connection terminal T212, and a ground terminal T213. The first external connection terminal T211 is connected to the other end of the connection line L10. The ground terminal T213 is connected to the ground line.

[0069] The important emergency loads 22 include loads that undertake functions related to the driving operation, stopping operation, or driving control of the vehicle V. The important emergency loads 22 are loads that undertake functions related to the execution of the minimum risk maneuver (MRM), which is the minimum driving operation, stopping operation, or driving control required to safely move the vehicle V to the shoulder of the road and stop even in the event of a loss of driving force from the driving source. The important emergency loads 22 include the above-mentioned ECU 50 that is capable of executing driving control of the vehicle V. In addition, the important emergency loads 22 may also include at least one of auxiliary loads such as an automatic braking device for braking the vehicle V, auxiliary loads such as an automatic steering device for steering the vehicle V, and auxiliary loads such as a light detection and ranging (LiDAR) for obtaining external information of the vehicle V.

[0070] The emergency important load 22 of the backup power supply system 20 and the normal load 12 of the main power supply system 10 may also have some overlapping functions. For example, the emergency important load 22 may also be a load that overlaps with a part of the normal load 12 of the main power supply system 10. Thus, the emergency important load 22 can be multiplexed and redundant. In other words, the functions that are repeated in the normal load 12 of the main power supply system 10 and the emergency important load 22 can be operated by the main power supply system 10 and can also be operated by the backup power supply system 20. Thus, the functions that are repeated in the normal load 12 of the main power supply system 10 and the emergency important load 22 are configured so that they can be operated even if an abnormality occurs in the main power supply system 10, and can also be operated even if an abnormality occurs in the backup power supply system 20.

[0071] In an emergency, the important load 22 is connected to the second external connection terminal T212 of the backup power supply unit 21 through the connection line L21.

[0072] The switching device 24 includes a first terminal T241, a second terminal T242, and a third terminal T243. The first terminal T241 is connected to the first external connection terminal T211 of the backup power supply unit 21 via a connection line L211. The second terminal T242 is connected to the second external connection terminal T212 of the backup power supply unit 21 via a connection line L212.

[0073] The switching device 24 includes a connecting line L241 that connects the first terminal T241 and the second terminal T242. A first switch SW1 is provided on the connecting line L241. In the present embodiment, the first switch SW1 is a switch having a normally open (NO) contact. A normally open contact is a contact that maintains the first switch SW1 in an open state and the connecting line L241 in a disconnected state when no operating signal is applied to the first switch SW1. Specifically, in the case of an electromagnetic switch (e.g., an electromagnetic contactor, an electromagnetic switch) in which the operating force is an electromagnetic force, the first switch SW1 is maintained in an open state and the connecting line L241 is maintained in a disconnected state when no electromagnetic force caused by the operating current is generated. The first switch SW1 is, for example, a semiconductor switch.

[0074] The switching device 24 includes a connection line L242 that connects the connection line L241 to the third terminal T243. One end of the connection line L242 is connected to the connection line L241 at a contact C241 formed between the first switch SW1 and the second terminal T242 of the connection line L241, and the other end is connected to the third terminal T243. A second switch SW2 is provided on the connection line L242. In this embodiment, the second switch SW2 is a DC-DC converter (DC / DC CONY). When the second switch SW2 is in the on state, the connection line L242 is maintained in the connected state, and when it is in the off state, the connection line L242 is maintained in the disconnected state. Furthermore, since the second switch SW2 is a DC-DC converter, when the second switch SW2 is in the on state, the voltage of the power flowing in the connection line L242 can be increased or decreased. In this way, the second switch SW2 can switch the connection line L242 between a connected state and a disconnected state, and can step up or down the voltage of the power flowing through the connection line L242 when the connection line L242 is in the connected state.

[0075] The switching device 24 includes a connection line L243 connected in parallel with the connection line L241. One end of the connection line L243 is connected to a contact C242 formed between the first terminal T241 and the first switch SW1 on the connection line L241, and the other end is connected to a contact C243 formed between the contact C241 and the second terminal T242 on the connection line L241. A third switch SW3 is provided on the connection line L243. In this embodiment, the third switch SW3 is a switch having a normally closed (NC) contact. A normally closed contact is a contact that maintains the third switch SW3 in an on state and the connection line L243 in a connected state when no operating signal is applied to the third switch SW3. Specifically, in the case of an electromagnetic switch (e.g., an electromagnetic contactor or an electromagnetic switch) whose operating force is electromagnetic force, the third switch SW3 is maintained in an on state and the connection line L243 is maintained in a connected state when no electromagnetic force is generated by the operating current. The third switch SW3 is, for example, a semiconductor switch.

[0076] Thus, in the backup power supply system 20, the first switch SW1 having a normally open contact and the third switch SW3 having a normally closed contact are provided in parallel.

[0077] When at least one of the first switch SW1 and the third switch SW3 is in the on state, the backup power supply system 20 is connected to the main power supply system 10, and power from the backup low-voltage power supply 23 can be supplied to the main power supply system 10, and power can be supplied from the main power supply system 10 to the emergency critical load 22. On the other hand, when both the first switch SW1 and the third switch SW3 are in the off state, the connection between the backup power supply system 20 and the main power supply system 10 is cut off.

[0078] Therefore, even in a state where electric power is not being supplied to the backup power supply control device 25 , electric power can be supplied from the main power supply system 10 to the emergency important load 22 .

[0079] In this embodiment, the first switch SW1 and the third switch SW3 are modularized into a switch module 241 .

[0080] Switching device 24 includes a connection line L244 connecting connection line L241 to a ground line. One end of connection line L244 is connected to contact C244 formed between first switch SW1 and contact C241 on connection line L241, and the other end is connected to the ground line. A capacitor CP is provided on connection line L244.

[0081] The backup low-voltage power supply 23 is, for example, a secondary battery such as a lithium-ion battery, and outputs power at a voltage of, for example, 12 V.

[0082] The backup low-voltage power supply 23 is provided on the connection line L213. One end of the connection line L213 is connected to the third terminal T243 of the switching device 24, and the other end is connected to the ground line. The backup low-voltage power supply 23 is provided on the connection line L213 so that the positive side is connected to the third terminal T243 of the switching device 24, and the negative side is connected to the ground line.

[0083] Therefore, when the second switch SW2 is in the on state, the backup low-voltage power supply 23 supplies power to the backup power supply system 20 from the connection line L213 through the connection line L242 of the switching device 24. At this time, the power output from the backup low-voltage power supply 23 is stepped up or down to the desired voltage by the second switch SW2 and supplied to the backup power supply system 20. On the other hand, when the second switch SW2 is in the off state, the connection line L242 of the switching device 24 is disconnected, and therefore the backup low-voltage power supply 23 does not supply power to the backup power supply system 20.

[0084] The backup power supply control device 25 includes a processor (not shown) such as a CPU (Central Processing Unit) and a storage medium 25 a such as a ROM (Read Only Memory).

[0085] The backup power supply control device 25 operates using the power stored in the backup low-voltage power supply 23 , for example.

[0086] The backup power supply control device 25 controls the first switch SW1, the second switch SW2, and the third switch SW3 using a program stored in the storage medium 25a. Specifically, the backup power supply control device 25 switches the first switch SW1, the second switch SW2, and the third switch SW3 between the on and off states. The backup power supply control device 25 is connected to the first switch SW1, the second switch SW2, and the third switch SW3 via signal lines. The backup power supply control device 25 transmits operation signals to the first switch SW1, the second switch SW2, and the third switch SW3 via the signal lines. The operation signals include signals that switch the first switch SW1, the second switch SW2, and the third switch SW3 between the on and off states.

[0087] The backup power supply control device 25 can execute a backup low-voltage power supply status estimation process using a program stored in the storage medium 25a. This process estimates whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22. The details of the backup low-voltage power supply status estimation process will be described later. Furthermore, based on the estimation results of the backup low-voltage power supply status estimation process, the backup power supply control device 25 can output a signal indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22.

[0088] <High-voltage power supply system>

[0089] The high-voltage power supply system 30 includes a high-voltage power supply 31 and a high-voltage load 32 .

[0090] The high-voltage power supply 31 is a secondary battery such as a lithium-ion battery, and outputs power at a higher voltage than the main low-voltage power supply 11 and the backup low-voltage power supply 23. The high-voltage power supply 31 outputs power at, for example, 200 V.

[0091] The high-voltage power supply 31 is connected to a connection line L31. One end of the connection line L31 is connected to the ground line, and the negative electrode side of the high-voltage power supply 31 is connected to the ground line side of the connection line L31.

[0092] The high-voltage load 32 operates at a higher voltage than the normal load 12 and the emergency important load 22. In this embodiment, the high-voltage load 32 includes a drive unit 321 for driving the vehicle V and an air conditioner (A / C) 322 for adjusting the temperature inside the vehicle V.

[0093] The drive unit 321 includes a rotary electric machine MG that generates power for driving the vehicle V and a power control unit PCU that controls the rotary electric machine MG. The power control unit PCU includes a DC-DC converter, an inverter, and the like.

[0094] The drive unit 321 is connected to the other end of the connection line L31. The high-voltage power supply 31 can supply power to the drive unit 321. The drive unit 321 uses the power control unit PCU to convert the DC power supplied from the high-voltage power supply 31 into three-phase AC power, and then supplies this three-phase AC power to the rotating electric machine MG. The rotating electric machine MG thus generates power to propel the vehicle V using the power from the high-voltage power supply 31. Furthermore, when the vehicle V is braking, the drive unit 321 can utilize the three-phase AC power generated by the rotating electric machine MG, convert this into DC power using the power control unit PCU, and use this DC power to charge the high-voltage power supply 31.

[0095] Air conditioner 322 is connected to connection line L32, which is connected to connection line L31 at contact point C31 formed on connection line L31 between high-voltage power supply 31 and drive unit 321. Air conditioner 322 is operated by power from high-voltage power supply 31.

[0096] <Pressure Reducing Device>

[0097] Voltage reducing device 40 is provided on connection line L40. One end of connection line L40 is connected to contact C32 formed between high-voltage power supply 31 and contact C31 on connection line L31, and the other end is connected to contact C12 formed between contact C11 on connection line L10 and the other end of connection line L10 (i.e., first external connection terminal T211 of backup power supply unit 21 of backup power supply system 20).

[0098] In this manner, the high-voltage power supply system 30 is connected to the main power supply system 10 and the backup power supply system 20 via the voltage step-down device 40 .

[0099] The step-down device 40 steps down the voltage of the power flowing through the high-voltage power supply system 30. The step-down device 40 is, for example, a DC-DC converter. Therefore, the power flowing through the high-voltage power supply system 30 is reduced in voltage by the step-down device 40 and can be supplied to the main power supply system 10 and the backup power supply system 20.

[0100] Furthermore, the voltage reducing device 40 can be switched between a connected state and a disconnected state. When the voltage reducing device 40 is in the connected state, the high-voltage power supply system 30 is connected to the main power supply system 10 and the backup power supply system 20 via the connection line L40 and the voltage reducing device 40. When the voltage reducing device 40 is in the disconnected state, the connection between the high-voltage power supply system 30 and the main power supply system 10 and the backup power supply system 20 is disconnected.

[0101] Therefore, even if the remaining amount of power stored in the main low-voltage power supply 11 of the main power supply system 10 and the backup low-voltage power supply 23 of the backup power supply system 20 is exhausted, the vehicle power supply system 1 can still supply power from the high-voltage power supply system 30 to the normal loads 12 of the main power supply system 10 and the critical emergency loads 22 of the backup power supply system 20 via the step-down device 40. Thus, even if the remaining amount of power stored in the main low-voltage power supply 11 of the main power supply system 10 and the backup low-voltage power supply 23 of the backup power supply system 20 is exhausted, the vehicle power supply system 1 can still operate the normal loads 12 of the main power supply system 10 and the critical emergency loads 22 of the backup power supply system 20.

[0102] Furthermore, the vehicle power supply system 1 can charge the main low-voltage power supply 11 of the main power supply system 10 via the step-down device 40 using the power of the high-voltage power supply 31 of the high-voltage power supply system 30. This prevents the main low-voltage power supply 11 of the main power supply system 10 from being depleted.

[0103] Furthermore, the vehicle power supply system 1 can charge the backup low-voltage power supply 23 of the backup power supply system 20 using the power from the high-voltage power supply 31 of the high-voltage power supply system 30 via the voltage step-down device 40. Specifically, the backup power supply control device 25 controls at least one of the first switch SW1 and the third switch SW3 to be in the on state, and controls the second switch SW2 to be in the on state, thereby charging the backup low-voltage power supply 23 of the backup power supply system 20 using the power from the high-voltage power supply 31 of the high-voltage power supply system 30 via the voltage step-down device 40. This prevents the backup low-voltage power supply 23 of the backup power supply system 20 from being depleted.

[0104]

Operation of vehicle power supply system

[0105] Next, refer to Figures 2 to 9 The operation of vehicle power supply system 1 will be described.

[0106] In this specification, etc., the on-state of the vehicle power supply system 1 refers to a state in which the vehicle power supply system 1 has been turned on, the drive source of the vehicle V has been started, and the power required to drive the vehicle V is being supplied to the auxiliary devices required for driving. This refers to a state in which the vehicle V is traveling or is immediately ready to travel. In this embodiment, the on-state of the vehicle power supply system 1 refers to a state in which the drive unit 321 is activated and the normal loads 12 and the emergency critical loads 22 are activated. For example, the on-state operation of the vehicle power supply system 1 occurs when the operator of the vehicle V turns on a power switch (not shown) provided on the vehicle V. Furthermore, if the vehicle V is equipped with an internal combustion engine, the on-state of the vehicle power supply system 1 may also occur when the internal combustion engine is started and the normal loads 12 and the emergency critical loads 22 are activated. Furthermore, if the vehicle V is equipped with an internal combustion engine, the on-state operation of the vehicle power supply system 1 may also occur when the operator of the vehicle V turns on the ignition power switch provided on the vehicle V.

[0107] On the other hand, the off state of the vehicle power supply system 1 refers to a state in which the vehicle power supply system 1 has been shut down, the vehicle V's drive source has not been activated, and no power required to drive the vehicle V is being supplied to auxiliary equipment required for driving. In this embodiment, the off state of the vehicle power supply system 1 refers to a state in which the high-voltage load 32 including the drive unit 321 is not activated, the normal loads 12 and the emergency essential loads 22 are not activated, and standby power is being supplied to the normal loads 12 and the emergency essential loads 22. The shut-down operation of the vehicle power supply system 1 may, for example, be the operator of the vehicle V turning off a power switch (not shown) provided on the vehicle V. Furthermore, if the vehicle V is equipped with an internal combustion engine, the shut-down state of the vehicle power supply system 1 may also be a state in which the internal combustion engine is not started, the normal loads 12 and the emergency essential loads 22 are not started, and standby power is being supplied to the normal loads 12 and the emergency essential loads 22. Furthermore, if the vehicle V is equipped with an internal combustion engine, the shut-down operation of the vehicle power supply system 1 may, for example, be the operator of the vehicle V turning off the ignition power switch provided on the vehicle V.

[0108] The operation of the vehicle power supply system 1 described below is realized by executing a program stored in advance in the backup power supply control device 25 .

[0109] <Operation of the Vehicle Power System When the Vehicle Power System is Off>

[0110] like Figure 2 As shown, first, in step S110, it is determined whether the vehicle power system 1 is turned off. Before the vehicle power system 1 is turned off, the vehicle power system 1 is in a standby state (step S110: No loop). If the vehicle power system 1 is turned off (step S110: Yes), the process proceeds to step S120.

[0111] In step S120, the temperature T0 of the backup low-voltage power supply 23 when the vehicle power supply system 1 is shut down is acquired. Then, the process proceeds to step S130.

[0112] In step S130 , the measurement of the discharge amount Q of the backup low-voltage power supply 23 after the vehicle power supply system 1 is shut down is started. Then, the process proceeds to step S140 .

[0113] In step S140 , the number of skipping times of the low-voltage backup power supply state estimation process is set to N = 0. Then, the process proceeds to step S150 .

[0114] In step S150, the measurement of the elapsed time t is started. Then, the process proceeds to step S210 (refer to Figure 3 ).

[0115] like Figure 3 As shown, in step S210, a determination is made as to whether the elapsed time t measured since step S150 is greater than or equal to a predetermined time tset. The predetermined time tset can be preset to any value, such as 4 hours, 12 hours, 24 hours, 120 hours (5 days), or 168 hours (1 week). For example, the predetermined time tset can be set based on a prediction of the time until the vehicle power supply system 1 is next turned on, using machine learning or other means based on past usage of the vehicle V. If the elapsed time t is not greater than or equal to the predetermined time tset, the vehicle power supply system 1 remains in a standby state until the elapsed time t becomes greater than or equal to the predetermined time tset (a loop of step S210: No). If the elapsed time t is greater than or equal to the predetermined time tset (step S210: Yes), the process proceeds to step S220.

[0116] In step S220, the temperature T of the backup low-voltage power supply 23 is obtained. Based on the obtained temperature T of the backup low-voltage power supply 23 and the temperature T0 of the backup low-voltage power supply 23 when the vehicle power supply system 1 was most recently shut down, obtained in step S120, a temperature difference ΔT = |T-T0| is calculated. The process then proceeds to step S230.

[0117] In step S230, it is determined whether the temperature difference ΔT (=|T-T0|) obtained in step S220 is greater than or equal to a predetermined value Tset. If the temperature difference ΔT is greater than or equal to the predetermined value Tset (step S230: Yes), the process proceeds to step S240. If the temperature difference ΔT is not greater than or equal to the predetermined value Tset (step S230: No), the process proceeds to step S250.

[0118] In step S240, it is determined whether the discharge amount Q of the backup low-voltage power supply 23 measured in step S130 after the vehicle power supply system 1 was recently shut down is greater than the specified value Qset. If the discharge amount Q is greater than the specified value Qset (step S240: Yes), the process proceeds to step S300, and the backup power supply control device 25 executes the backup low-voltage power supply state estimation process described later (see Figure 6 as well as Figure 7 ). When the discharge amount Q is not greater than the predetermined value Qset (step S240: No), the process proceeds to step S250.

[0119] In step S250, it is determined whether the number of skip times N[times] of the backup low-voltage power supply state estimation process exceeds the specified number Nset[times]. The specified number Nset[times] can be set to any number, such as 3[times], 5[times], etc. If the number of skip times N[times] of the backup low-voltage power supply state estimation process exceeds the specified number Nset[times] (step S250: Yes), the process proceeds to step S300, and the backup power supply control device 25 executes the backup low-voltage power supply state estimation process described later (refer to Figure 6 as well as Figure 7 ). When the number of skip times N[times] of the backup low-voltage power supply state estimation process does not exceed the prescribed number Nset[times] (step S250: No), the backup low-voltage power supply state estimation process is not executed, and the process proceeds to step S260. Therefore, when the vehicle power supply system 1 is in the off state for a long time, the backup low-voltage power supply state estimation process is executed every time (prescribed time tset)×(prescribed number Nset[times]) elapses, regardless of the values of the temperature difference ΔT and the discharge amount Q. Thus, when the vehicle power supply system 1 is in the off state for a long time, regardless of the values of the temperature difference ΔT and the discharge amount Q, it is possible to confirm by estimation at regular intervals whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency.

[0120] In step S260 , the number of times N [times] of skipping the low-voltage backup power supply state estimation process is incremented by 1 and set to N+1 [times]. Then, the process proceeds to step S270 .

[0121] In step S270 , the elapsed time t is reset to t=0, and the measurement of the elapsed time t is restarted. Then, the process returns to step S210 .

[0122] In this way, when the vehicle power supply system 1 is in the off state and the state of the vehicle V meets the specified conditions, the backup low-voltage power supply state estimation processing is executed. When the state of the vehicle V does not meet the specified conditions, the backup low-voltage power supply state estimation processing is not executed and skipped, and returns to step S210.

[0123] (Backup low-voltage power supply status estimation processing)

[0124] Here, refer to Figure 6 as well as Figure 7 An example of the backup low-voltage power supply state estimation process will be described.

[0125] like Figure 6 as well as Figure 7 As shown, in step S300, when the backup low-voltage power supply status estimation process begins, the process first proceeds to step S301, where the required remaining capacity Rset of the backup low-voltage power supply 23 is calculated. The required remaining capacity Rset calculated when the vehicle power supply system 1 is in the off state, i.e., the required remaining capacity Rset calculated during the backup low-voltage power supply status estimation process in step S300, is the power capacity required by the backup low-voltage power supply 23 to operate the emergency critical load 22 after (predetermined time tset) - (elapsed time t) has elapsed from the time the required remaining capacity Rset is calculated. This required remaining capacity Rset is calculated based on the temperature T of the backup low-voltage power supply 23 obtained in step S220 and the discharge capacity Q of the backup low-voltage power supply 23 measured starting in step S130 after the vehicle power supply system 1 is shut down. The process then proceeds to step S302.

[0126] In step S302, a determination is made as to whether the remaining amount R of the backup low-voltage power supply 23 is greater than or equal to the required remaining amount Rset calculated in step S301. For example, the open circuit voltage (OCV) of the backup low-voltage power supply 23 is measured, and the remaining amount R of the backup low-voltage power supply 23 is calculated based on the measured open circuit voltage. If the remaining amount R of the backup low-voltage power supply 23 is greater than or equal to the required remaining amount Rset (step S302: Yes), the process proceeds to step S303. If the remaining amount R of the backup low-voltage power supply 23 is not greater than or equal to the required remaining amount Rset calculated in step S301 (step S302: No), the process proceeds to step S323, where the result of the backup low-voltage power supply state estimation processing is set as "due to insufficient remaining amount of power in the backup low-voltage power supply 23, the backup low-voltage power supply 23 is unable to supply power to operate the emergency critical load 22," and the backup low-voltage power supply state estimation processing is terminated.

[0127] In step S303, power supply from the backup low-voltage power supply 23 to the emergency essential load 22 begins, and measurement of the power supply time t1 from the backup low-voltage power supply 23 to the emergency essential load 22 begins. Furthermore, in step S303, measurement of the internal resistance of the backup low-voltage power supply 23 begins. The process then proceeds to step S304.

[0128] In step S304, a determination is made as to whether a predetermined time t1set has elapsed since the start of power supply from the backup low-voltage power supply 23 to the emergency critical load 22 in step S303. Specifically, a determination is made as to whether the power supply time t1 from the backup low-voltage power supply 23 to the emergency critical load 22, measured starting in step S303, is greater than or equal to the predetermined time t1set. The predetermined time t1set is set, for example, based on the total time required to determine whether an abnormality has occurred in the main power supply system 10, the time required to execute a driver replacement request if an abnormality has occurred in the main power supply system 10, and the time required to execute the minimum required driving, stopping, and driving control, i.e., the minimum risk management (MRM), to safely move the vehicle V to the shoulder of the road and stop. The predetermined time t1set is set, for example, to an arbitrary time between approximately 20 and 60 seconds. When the power supply time t1 from the backup low-voltage power supply 23 to the important emergency load 22 is not longer than the specified time t1set (step S304: no loop), continue to supply power from the backup low-voltage power supply 23 to the important emergency load 22 until the power supply time t1 from the backup low-voltage power supply 23 to the important emergency load 22 becomes longer than the specified time t1set. If the power supply time t1 from the backup low-voltage power supply 23 to the important emergency load 22 becomes longer than the specified time t1set (step S304: yes), enter step S305.

[0129] In step S305, the power supply from the backup low-voltage power supply 23 to the emergency important load 22 started in step S303 is terminated. Then, the process proceeds to step S306.

[0130] In step S306, a determination is made as to whether power of a specified voltage was supplied from the backup low-voltage power supply 23 to the emergency essential load 22 during the period from step S303 to step S305, that is, during the specified time t1set from the start of power supply from the backup low-voltage power supply 23 to the emergency essential load 22 in step S303. If power of the specified voltage was supplied from the backup low-voltage power supply 23 to the emergency essential load 22 (step S306: Yes), the process proceeds to step S307. If power of the specified voltage was not supplied from the backup low-voltage power supply 23 to the emergency essential load 22 (step S306: No), the process proceeds to step S322, where the result of the backup low-voltage power supply state estimation processing is set to "due to performance degradation of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is in a state incapable of supplying power to operate the emergency essential load 22," and the backup low-voltage power supply state estimation processing is terminated.

[0131] Thus, in this embodiment, during a predetermined time t1set, which is set based on the total time required to determine whether an abnormality has occurred in the main power system 10, the time to execute a driver replacement request if an abnormality has occurred in the main power system 10, and the time required to execute the Minimal Risk Maneuver (MRM), power is actually supplied from the backup low-voltage power supply 23 to the emergency critical load 22, and a determination is made as to whether power of a predetermined voltage has been supplied from the backup low-voltage power supply 23 to the emergency critical load 22. This allows determination of whether an abnormality has occurred in the main power system 10, execution of a driver replacement request if an abnormality has occurred in the main power system 10, and, if an abnormality has occurred in the main power system 10, more accurately determination of whether the backup low-voltage power supply 23 can continue to supply power of a predetermined voltage to the emergency critical load 22 until the Minimal Risk Maneuver (MRM) is completed.

[0132] In step S307, a determination is made as to whether the remaining power level R of the backup low-voltage power supply 23 is greater than or equal to the required remaining power level Rset obtained in step S301. Since power was supplied from the backup low-voltage power supply 23 to the emergency critical load 22 during the period from step S303 to step S305, the remaining power level R of the backup low-voltage power supply 23 decreased. Therefore, even if the remaining power level R of the backup low-voltage power supply 23 is greater than or equal to the required remaining power level Rset obtained in step S301 in step S302, the remaining power level R of the backup low-voltage power supply 23 may still be less than the required remaining power level Rset obtained in step S301 in step S307. If the remaining power level R of the backup low-voltage power supply 23 is greater than or equal to the required remaining power level Rset obtained in step S301 (step S307: Yes), the process proceeds to step S311. If the remaining power level R of the backup low-voltage power supply 23 is not greater than or equal to the required remaining power level Rset obtained in step S301, the process proceeds to step S308.

[0133] In step S308, charging of the backup low-voltage power supply 23 is started. The power for charging the backup low-voltage power supply 23 is supplied from at least one of the high-voltage power supply 31 and the main low-voltage power supply 11. Then, the process proceeds to step S309.

[0134] In step S309, similar to step S307, a determination is made as to whether the remaining amount R of the backup low-voltage power supply 23 is greater than or equal to the required remaining amount Rset obtained in step S301. If the remaining amount R of the backup low-voltage power supply 23 is not greater than or equal to the required remaining amount Rset obtained in step S301, charging of the backup low-voltage power supply 23 continues until the remaining amount R of the backup low-voltage power supply 23 reaches or exceeds the required remaining amount Rset obtained in step S301 (a loop of step S309: No). If the remaining amount R of the backup low-voltage power supply 23 is greater than or equal to the required remaining amount Rset obtained in step S301 (step S309: Yes), the process proceeds to step S310, and charging of the backup low-voltage power supply 23 is terminated. The process then proceeds to step S311.

[0135] By executing the processing from step S308 to step S310, even if the power of the backup low-voltage power supply 23 is consumed during the period from step S303 to step S305, that is, during the specified time t1set from the start of power supply from the backup low-voltage power supply 23 to the emergency important load 22 in step S303, and the remaining power R of the backup low-voltage power supply 23 is less than the required remaining power Rset obtained in step S301, the remaining power R of the backup low-voltage power supply 23 can be returned to above the required remaining power Rset obtained in step S301.

[0136] In step S311, the measurement of the internal resistance value of the backup low-voltage power supply 23 started in step S303 is terminated. Then, after step S311, the process proceeds to step S312.

[0137] In step S312, the internal impedance Z of the backup low-voltage power supply 23 is calculated based on the internal resistance value of the backup low-voltage power supply 23 measured from the start of power supply from the backup low-voltage power supply 23 to the emergency important load 22 in step S303 to the termination of measurement of the internal resistance value of the backup low-voltage power supply 23 in step S311. The process then proceeds to step S313.

[0138] In step S313, based on the internal impedance Z of the backup low-voltage power supply 23 calculated in step S312, a determination is made as to whether the power supplied from the backup low-voltage power supply 23 to the emergency essential load 22 during the period from step S303 to step S305, that is, during the predetermined time t1set from the start of power supply from the backup low-voltage power supply 23 to the emergency essential load 22 in step S303, satisfies the current value required to operate the emergency essential load 22. For example, if the internal impedance Z of the backup low-voltage power supply 23 is large, even if power of a predetermined voltage is supplied from the backup low-voltage power supply 23 to the emergency essential load 22, the current supplied from the backup low-voltage power supply 23 to the emergency essential load 22 may be reduced, and the current required to operate the emergency essential load 22 may not be supplied. In step S313, based on the internal impedance Z of the backup low-voltage power supply 23 calculated in step S312, it is determined whether the power supplied from the backup low-voltage power supply 23 to the emergency important load 22 during the period from step S303 to step S305, that is, during the specified time t1set from the start of power supply from the backup low-voltage power supply 23 to the emergency important load 22 in step S303, meets the current value required to operate the emergency important load 22. This enables a more accurate determination of whether the emergency important load 22 can be operated by the power supplied from the backup low-voltage power supply 23 to the emergency important load 22 when an abnormality occurs in the main power supply system 10.

[0139] In step S313, based on the internal impedance Z of the backup low-voltage power supply 23 calculated in step S312, when it is determined that the required current is supplied from the backup low-voltage power supply 23 to the emergency important load 22 during the period from step S303 to step S305, that is, during the specified time t1set from the start of power supply from the backup low-voltage power supply 23 to the emergency important load 22 in step S303 (step S313: yes), step S321 is entered, and the inference result of the backup low-voltage power supply status inference processing is set to "the backup low-voltage power supply 23 is in a state where it can supply power to operate the emergency important load 22", and the backup low-voltage power supply status inference processing is terminated.

[0140] On the other hand, in step S313, based on the internal impedance Z of the backup low-voltage power supply 23 calculated in step S312, if it is determined that the required current is not supplied from the backup low-voltage power supply 23 to the emergency important load 22 during the period from step S303 to step S305, that is, during the specified time t1set from the start of power supply from the backup low-voltage power supply 23 to the emergency important load 22 in step S303 (step S313: No), step S322 is entered, and the inference result of the backup low-voltage power supply status inference processing is set to "due to the degradation of the performance of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is in a state where it cannot supply power to operate the emergency important load 22", and the backup low-voltage power supply status inference processing is terminated.

[0141] Thus, a series of processes of the standby low-voltage power supply state estimation process is terminated.

[0142] return Figure 4 When the standby low-voltage power supply state estimation process in step S300 is terminated, step S410 is entered.

[0143] In step S410, a determination is made as to whether the result of the backup low-voltage power supply status estimation process in step S300 indicates that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22. If the result of the backup low-voltage power supply status estimation process in step S300 indicates that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22 (step S410: Yes), the process proceeds to step S471. If the result of the backup low-voltage power supply status estimation process in step S300 indicates that the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 (step S410: No), the process proceeds to step S420.

[0144] In step S420, a determination is made as to whether the result of the backup low-voltage power supply state estimation process in step S300 is "the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 due to insufficient remaining power in the backup low-voltage power supply 23." If the result of the backup low-voltage power supply state estimation process in step S300 is "the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 due to insufficient remaining power in the backup low-voltage power supply 23" (step S420: YES), the process proceeds to step S430. When the inference result of the backup low-voltage power supply status inference processing in step S300 is not "due to insufficient remaining power storage of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency", that is, when the inference result of the backup low-voltage power supply status inference processing in step S300 is "due to the degradation of the performance of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is in a state where it cannot supply power to operate the important load 22 in an emergency" (step S420: No), go to step S472.

[0145] In step S430, information indicating that "the backup low-voltage power supply 23 is in a state where it cannot supply power to operate the emergency important load 22" is stored in the storage medium 25a. Then, the process proceeds to step S440.

[0146] In step S440, charging of the backup low-voltage power supply 23 is started. The power for charging the backup low-voltage power supply 23 is supplied from at least one of the high-voltage power supply 31 and the main low-voltage power supply 11. Then, the process proceeds to step S450.

[0147] In step S450, it is determined whether the remaining amount R of the backup low-voltage power supply 23 is greater than or equal to the required remaining amount Rset obtained in step S301. If the remaining amount R of the backup low-voltage power supply 23 is not greater than or equal to the required remaining amount Rset obtained in step S301, the backup low-voltage power supply 23 is continuously charged until the remaining amount R of the backup low-voltage power supply 23 becomes greater than or equal to the required remaining amount Rset obtained in step S301 (a loop of step S450: No).

[0148] If the remaining amount R of the backup low-voltage power supply 23 is greater than the required remaining amount Rset obtained in step S301 (step S450: Yes), the process proceeds to step S460, where charging of the backup low-voltage power supply 23 is terminated. The process then returns to step S300, where the backup low-voltage power supply state estimation process is executed again. At this point, through the processes of steps S440 to S460, the remaining amount R of the backup low-voltage power supply 23 has become greater than the required remaining amount Rset obtained in step S301. Therefore, in step S302, the remaining amount R of the backup low-voltage power supply 23 is greater than the required remaining amount Rset (step S302: Yes), and the process proceeds to step S303. Therefore, the inference result of the backup low-voltage power supply status inference processing in step S300 is "the backup low-voltage power supply 23 is in a state where it can supply power to operate the important load 22 in an emergency" (step S321), or "due to the degradation of the performance of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency" (step S322).

[0149] In step S471 , information indicating that “the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency important load 22 ” is stored in the storage medium 25 a , and the process proceeds to step S480 .

[0150] In step S472, information indicating that "the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22" is stored in the storage medium 25a. Then, the process proceeds to step S480.

[0151] In steps S471, S472, and S430, when information indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency is stored in the storage medium 25a through the previous series of processing, the information stored in the previous series of processing is rewritten and overwritten in the storage medium 25a.

[0152] In step S480, the elapsed time t is reset to t=0, and the measurement of the elapsed time t is restarted. Then, the process returns to step S210.

[0153] When the vehicle power supply system 1 is in the off state, the vehicle power supply system 1 repeatedly performs a series of processes from step S110 to step S480 described above.

[0154] <Operation of the Vehicle Power Supply System When the Vehicle Power Supply System Transitions from the Off State to the On State>

[0155] like Figure 5As shown, if the vehicle power supply system 1 is turned on when the vehicle power supply system 1 is in the off state, the series of processes from step S110 to step S480 described above are terminated and the process proceeds to step S510 .

[0156] In step S510, information indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22, stored in the storage medium 25a, is retrieved, and a determination is made as to whether the information stored in the storage medium 25a indicates that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22. After this determination, the information indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22, stored in the storage medium 25a, is deleted.

[0157] When the information stored in the storage medium 25a indicates that "the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency" (step S510: yes), the process proceeds to step S581, and the backup power supply control device 25 outputs a signal to the ECU 50 indicating that "the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency", and terminates a series of processing.

[0158] In this manner, when the vehicle power supply system 1 is in the off state and the state of the vehicle V satisfies specified conditions, the backup low-voltage power supply state estimation process is executed to estimate whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22. Therefore, if the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22, the backup power supply control device 25 can omit the backup low-voltage power supply state estimation process when the vehicle power supply system 1 transitions from the off state to the on state. Thus, if the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22, the backup power supply control device 25 can output a signal indicating that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22 to the ECU 50 in a short period of time when the vehicle power supply system 1 transitions from the off state to the on state.

[0159] In addition, when the specified condition is met that the time t elapsed since the vehicle power supply system 1 was last shut down is greater than the specified time tset, the backup low-voltage power supply state estimation processing is performed, thereby suppressing the power consumption of the vehicle power supply system 1 when it is in the shut-down state, and when there is a high probability that the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency due to the reduction of the remaining storage capacity R of the backup low-voltage power supply 23 due to the standby power of the normal load 12 and the important load 22 in an emergency, the backup low-voltage power supply state estimation processing can be performed.

[0160] Moreover, when the specified condition is satisfied that the temperature difference ΔT = |T-T0| between the temperature T of the backup low-voltage power supply 23 and the temperature T0 of the backup low-voltage power supply 23 when the vehicle power supply system 1 was most recently shut down is greater than the specified value Tset, the backup low-voltage power supply state estimation processing is performed. Therefore, when there is a high probability that the temperature T of the backup low-voltage power supply 23 drops or rises sharply after the vehicle power supply system 1 was most recently shut down and the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the important load 22 in an emergency, the backup low-voltage power supply state estimation processing is performed. When there is a low probability that the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the important load 22 in an emergency, the backup low-voltage power supply state estimation processing is not performed. Therefore, the power consumption when the vehicle power supply system 1 is in the shut-down state can be further suppressed.

[0161] In addition, when the specified condition is met that the discharge amount Q of the backup low-voltage power supply 23 after the vehicle power supply system 1 was recently shut down is greater than the specified value Qset, the backup low-voltage power supply state estimation processing is performed. Therefore, when there is a high probability that the discharge amount Q of the backup low-voltage power supply 23 increases after the vehicle power supply system 1 was recently shut down and the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency, the backup low-voltage power supply state estimation processing is performed. When there is a low probability that the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency, the backup low-voltage power supply state estimation processing is not performed. Therefore, the power consumption when the vehicle power supply system 1 is in the shut-down state can be further suppressed.

[0162] On the other hand, when the information stored in the storage medium 25a is not information indicating that "the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency" (step S510: No), that is, when the information stored in the storage medium 25a is information indicating that "the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the important load 22 in an emergency", or when the information indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency is not stored in the storage medium 25a, proceed to step S600.

[0163] In step S600, the backup low-voltage power supply state estimation process is executed. The backup low-voltage power supply state estimation process in step S600 is similar to the backup low-voltage power supply state estimation process in step S300 described above. Furthermore, the required remaining capacity Rset calculated in the backup low-voltage power supply state estimation process when the vehicle power supply system 1 is in the on-state, i.e., the required remaining capacity Rset calculated in the backup low-voltage power supply state estimation process in step S600, is the power capacity required by the backup low-voltage power supply 23 to operate the emergency critical load 22 at the time the required remaining capacity Rset is calculated.

[0164] If the backup low-voltage power supply state estimation process in step S600 is completed, the process proceeds to step S520 .

[0165] In step S520, a determination is made as to whether the result of the backup low-voltage power supply status estimation process in step S600 indicates that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22. If the result of the backup low-voltage power supply status estimation process in step S600 indicates that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22 (step S520: Yes), the process proceeds to step S581, where the backup power supply control device 25 outputs a signal to the ECU 50 indicating that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency essential load 22, and the series of processes terminates. If the result of the backup low-voltage power supply status estimation process in step S600 indicates that the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 (step S520: No), the process proceeds to step S530.

[0166] In step S530, a determination is made as to whether the result of the backup low-voltage power supply state estimation process in step S600 is "the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 due to insufficient remaining power in the backup low-voltage power supply 23." If the result of the backup low-voltage power supply state estimation process in step S600 is "the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 due to insufficient remaining power in the backup low-voltage power supply 23" (step S530: YES), the process proceeds to step S540. If the inference result of the backup low-voltage power supply status inference processing in step S600 is not "due to insufficient remaining power of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the important load 22 in an emergency" (step S530: No), that is, if the inference result of the backup low-voltage power supply status inference processing in step S600 is "due to reduced performance of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the important load 22 in an emergency", enter step S582.

[0167] In step S540 , the backup power supply control device 25 outputs a signal indicating that the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 to the ECU 50 .

[0168] In step S550, charging of the backup low-voltage power supply 23 is started. The power for charging the backup low-voltage power supply 23 is supplied from at least one of the high-voltage power supply 31 and the main low-voltage power supply 11. Then, the process proceeds to step S560.

[0169] In step S560, it is determined whether the remaining amount R of the backup low-voltage power supply 23 is greater than the required remaining amount Rset. If the remaining amount R of the backup low-voltage power supply 23 is not greater than the required remaining amount Rset, charging of the backup low-voltage power supply 23 is continued until the remaining amount R of the backup low-voltage power supply 23 becomes greater than the required remaining amount Rset (a loop of step S560: No).

[0170] If the remaining amount of power R of the backup low-voltage power supply 23 is greater than the required remaining amount Rset (step S560: yes), the process proceeds to step S570 to terminate the charging of the backup low-voltage power supply 23. Then, the process returns to step S600 and the backup low-voltage power supply state estimation process is executed again. At this time, by executing the processes of steps S550 to S570, the remaining amount of power R of the backup low-voltage power supply 23 becomes greater than the required remaining amount Rset. Therefore, the estimation result of the backup low-voltage power supply state estimation process in step S600 is "the backup low-voltage power supply 23 is in a state where it can supply power to operate the important load 22 in an emergency" (step S321), or "due to the degradation of the performance of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency" (step S322).

[0171] In step S582 , the backup power supply control device 25 outputs a signal indicating that the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 to the ECU 50 . The process then proceeds to step S583 .

[0172] In step S583, the backup power supply control device 25 outputs a signal indicating that the performance of the backup low-voltage power supply 23 has deteriorated to the ECU 50. Then, a series of processes are terminated.

[0173] As described above, in this embodiment, the vehicle V is capable of automatic driving under specific conditions. Furthermore, upon receiving a signal from the backup power supply control device 25 indicating that the backup low-voltage power supply 23 is capable of supplying power to operate the critical load 22 in an emergency, the ECU 50 permits automatic driving of the vehicle V. This enables the vehicle V to be driven automatically.

[0174] On the other hand, if the backup power supply control device 25 receives a signal indicating that the backup low-voltage power supply 23 is not in a state capable of supplying power to operate the emergency essential load 22 , the ECU 50 disallows the automatic driving of the vehicle V. As a result, the vehicle V suspends the automatic driving.

[0175] Furthermore, upon inputting a signal indicating that the performance of the backup low-voltage power supply 23 has degraded from the backup power supply control device 25, the ECU 50 activates, for example, a notification device (not shown) provided in the interior of the vehicle V, to notify the user of the vehicle V of the degraded performance of the backup low-voltage power supply 23. The notification device may be a display device capable of indicating that the performance of the backup low-voltage power supply 23 has degraded, or may be an indicator lamp that illuminates when the performance of the backup low-voltage power supply 23 has degraded.

[0176] (Modification of the Backup Low-Voltage Power Supply State Estimation Process)

[0177] The backup low voltage power state estimation process in step S300 and step S600 can also refer to the Figure 6 and Figure 7 Here, refer to Figure 8 A modified example of the low-voltage backup power supply state estimation process will be described.

[0178] like Figure 8 As shown, the backup low-voltage power supply status estimation process first enters step S341 to calculate the required remaining capacity Rset of the backup low-voltage power supply 23. Step S341 is the same process as step S301 described above. The required remaining capacity Rset calculated when the vehicle power supply system 1 is in the off state, that is, the required remaining capacity Rset calculated in the backup low-voltage power supply status estimation process in step S300, refers to the power capacity required by the backup low-voltage power supply 23 to operate the important load 22 in an emergency after (predetermined time tset) - (elapsed time t) from the time when the required remaining capacity Rset is calculated, based on the temperature T of the backup low-voltage power supply 23 obtained in step S220 and the discharge capacity Q of the backup low-voltage power supply 23 measured starting in step S130 after the vehicle power supply system 1 is shut down. On the other hand, the required remaining capacity Rset calculated during the backup low-voltage power supply state estimation process when the vehicle power supply system 1 is in the on state, i.e., the required remaining capacity Rset calculated during the backup low-voltage power supply state estimation process in step S600, is the power capacity required by the backup low-voltage power supply 23 to operate the emergency important load 22 at the time the required remaining capacity Rset is calculated. Then, the process proceeds to step S342.

[0179] In step S342, the backup low-voltage power supply 23 is charged for a predetermined period of time in order to manage and estimate the status of the backup low-voltage power supply 23. The power used to charge the backup low-voltage power supply 23 is supplied from at least one of the high-voltage power supply 31 and the main low-voltage power supply 11. Furthermore, in step S342, the current and voltage of the power flowing through the backup low-voltage power supply 23 are continuously measured during the predetermined period of time during which the backup low-voltage power supply 23 is charged. Furthermore, in step S342, the internal resistance of the backup low-voltage power supply 23 may also be continuously measured during the predetermined period of time during which the backup low-voltage power supply 23 is charged. If charging of the backup low-voltage power supply 23 is terminated after the predetermined period of time in step S342, the process proceeds to step S343.

[0180] In step S343, the remaining amount of power R of the backup low-voltage power supply 23 after charging the backup low-voltage power supply 23 in step S342 is calculated. The remaining amount of power R of the backup low-voltage power supply 23 is calculated, for example, based on the current and voltage values of the power flowing through the backup low-voltage power supply 23, which are continuously measured while charging the backup low-voltage power supply 23 in step S342. The process then proceeds to step S344.

[0181] In step S344, a determination is made as to whether the remaining amount R of the backup low-voltage power supply 23 calculated in step S343 is greater than or equal to the required remaining amount Rset. If the remaining amount R of the backup low-voltage power supply 23 calculated in step S343 is greater than or equal to the required remaining amount Rset (step S344: Yes), the process proceeds to step S345. If the remaining amount R of the backup low-voltage power supply 23 calculated in step S343 is not greater than or equal to the required remaining amount Rset (step S344: No), the process proceeds to step S353, where the result of the backup low-voltage power supply state estimation processing is set to "due to insufficient remaining amount of power in the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state capable of supplying sufficient power to operate the emergency critical load 22," and the backup low-voltage power supply state estimation processing is terminated.

[0182] In step S345, the internal impedance Z of the backup low-voltage power supply 23 is calculated. The internal impedance Z of the backup low-voltage power supply 23 is calculated, for example, based on the behavior of the current and voltage values of the power flowing through the backup low-voltage power supply 23, which are continuously measured while the backup low-voltage power supply 23 is being charged in step S342. Alternatively, the internal impedance Z of the backup low-voltage power supply 23 may be calculated based on the behavior of the internal resistance value of the backup low-voltage power supply 23, which is measured during the predetermined charging time in step S342. The process then proceeds to step S346.

[0183] In step S346, a determination is made as to whether the internal impedance Z of the backup low-voltage power supply 23 calculated in step S345 is less than or equal to a predetermined value Zset. If the internal impedance Z of the backup low-voltage power supply 23 calculated in step S345 is less than or equal to the predetermined value Zset (step S346: Yes), the process proceeds to step S351, where the result of the backup low-voltage power supply status estimation process is set as "the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency critical load 22," and the backup low-voltage power supply status estimation process is terminated.

[0184] On the other hand, in step S346, when the internal impedance Z of the backup low-voltage power supply 23 calculated in step S345 is not below the specified value Zset (step S346: No), step S352 is entered, and the inference result of the backup low-voltage power supply status inference processing is set to "due to the performance degradation of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is not in a state where it can supply power to operate the important load 22 in an emergency", and the backup low-voltage power supply status inference processing is terminated.

[0185] Thus, a series of processes of the standby low-voltage power supply state estimation process is terminated.

[0186] <Operation of the Vehicle Power System When the Vehicle Power System is On>

[0187] Next, the operation of the vehicle power supply system 1 when the vehicle power supply system 1 is in the ON state will be described.

[0188] (Normal operation of the vehicle power system when the vehicle power system is turned on)

[0189] First, the operation of the vehicle power supply system 1 in a normal state when the vehicle power supply system 1 is in the ON state will be described.

[0190] When the vehicle power supply system 1 is in the on-state and operating normally, the backup power supply control device 25 controls the first switch SW1 to be in the on-state, the second switch SW2 to be in the off-state, and the third switch SW3 to be in the off-state. That is, when the vehicle power supply system 1 is in the on-state and operating normally, the switching device 24 maintains the first switch SW1 in the on-state, the second switch SW2 in the off-state, and the third switch SW3 in the off-state. Thus, when the vehicle power supply system 1 is in the on-state and operating normally, the normal loads 12 and the emergency critical loads 22 operate using the power supplied from the main low-voltage power supply 11.

[0191] (Operation of the Vehicle Power System When an Abnormality Occurs in the Main Power System While the Vehicle Power System is On)

[0192] Next, refer to Figure 9 The operation of the vehicle power supply system 1 when an abnormality occurs in the main power supply system 10 while the vehicle power supply system 1 is in the ON state will be described.

[0193] A voltage sensor (not shown) is connected to the main low-voltage power supply 11 to detect the output voltage of the main low-voltage power supply 11. The voltage sensor outputs a signal indicating the output voltage of the main low-voltage power supply 11. The signal indicating the output voltage of the main low-voltage power supply 11 output from the voltage sensor can be input to the ECU 50 or to the backup power supply control device 25. When the signal indicating the output voltage of the main low-voltage power supply 11 is input to the backup power supply control device 25, the signal indicating the output voltage of the main low-voltage power supply 11 can be input to the backup power supply control device 25 via the ECU 50 or directly from the voltage sensor.

[0194] Furthermore, the vehicle power supply system 1 is capable of executing an abnormality determination process to determine whether an abnormality has occurred in the main power supply system 10. The abnormality determination process can be executed by the ECU 50 or by the backup power supply control device 25. Here, the control flow in the case where the abnormality determination process is executed by the backup power supply control device 25 is described as an example.

[0195] like Figure 9 As shown, first, in step S710, it is determined whether the vehicle power supply system 1 is in the ON state. If the vehicle power supply system 1 is in the ON state (step S710: Yes), the process proceeds to step S720, where abnormality determination processing is executed. On the other hand, if the vehicle power supply system 1 is not in the ON state, that is, if the vehicle power supply system 1 is in the OFF state, the abnormality determination processing is not performed, and the vehicle power supply system 1 is in the standby state until it is turned on (a loop of step S710: No). Thus, abnormality determination processing is not performed when the vehicle power supply system 1 is in the OFF state, thereby reducing power consumption in the vehicle power supply system 1.

[0196] In step S720, based on the signal indicating the output voltage of the main low-voltage power supply 11 input to the backup power supply control device 25, a determination is made as to whether the output voltage Vmain of the main low-voltage power supply 11 is less than the preset lower limit voltage Vmin. If the output voltage Vmain of the main low-voltage power supply 11 is not less than the preset lower limit voltage Vmin (step S720: No), the process proceeds to step S732, where it is determined that no abnormality has occurred in the main power supply system 10, and the process returns to step S710.

[0197] When the output voltage Vmain of the main low-voltage power supply 11 is lower than the preset lower limit voltage Vmin (step S720 : Yes), the process proceeds to step S731 , where it is determined that an abnormality has occurred in the main power supply system 10 , and the process proceeds to step S740 .

[0198] In step S740 , the backup power supply control device 25 controls to switch the first switch SW1 to an OFF state, switch the second switch SW2 to an ON state, and maintain the third switch SW3 in an OFF state.

[0199] Therefore, when the vehicle power supply system 1 is in the ON state, if the abnormality detection process is executed and it is determined that an abnormality has occurred in the main power supply system 10, the first switch SW1 and the third switch are both in the OFF state, thereby disconnecting the main power supply system 10 from the backup power supply system 20. Furthermore, because the second switch SW2 is in the ON state, power from the backup low-voltage power supply 23 is supplied to the backup power supply system 20 from the connection line L213 via the connection line L242 of the switching device 24. At this time, the power output from the backup low-voltage power supply 23 is stepped up or down to the desired voltage by the second switch SW2 and supplied to the backup power supply system 20. The power from the backup low-voltage power supply 23 is then supplied from the connection line L21 to the emergency critical load 22 via the connection line L241 and the connection line L212.

[0200] Then, when step S740 is completed, step S750 is entered, and the backup power supply control device 25 outputs a signal to the ECU 50 indicating that an abnormality has occurred in the main power supply system 10, the backup power supply system 20 and the main power supply system 10 are cut off, and the important load 22 is operated by the power from the backup low-voltage power supply 23 of the backup power supply system 20 in an emergency, and a series of processing is terminated.

[0201] When ECU50 receives a signal from the backup power supply system 20 indicating that an abnormality has occurred in the main power supply system 10, the backup power supply system 20 and the main power supply system 10 are disconnected, and the important load 22 is operated by the power of the backup low-voltage power supply 23 from the backup power supply system 20 in an emergency, it executes the minimum driving operation, stopping operation or driving control required to safely move the vehicle V to the shoulder of the road and stop, that is, the minimum risk strategy (MRM: Minimal Risk Maneuver).

[0202] Thus, even if an abnormality occurs in the main power supply system 10 while the vehicle power supply system 1 is in the on state, the emergency critical loads 22 can be operated using power from the backup low-voltage power supply 23. This allows for the minimum driving, stopping, or driving control required to safely move the vehicle V to the shoulder of the road and stop, namely, the Minimum Risk Maneuver (MRM). Furthermore, when the vehicle power supply system 1 transitions from the off state to the on state, the backup power supply control device 25 outputs a signal indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency critical loads 22. Therefore, the ECU 50 can control the driving of the vehicle V based on the signal indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the emergency critical loads 22. This allows for reliable power supply from the backup low-voltage power supply 23 to operate the emergency critical loads 22 even if an abnormality occurs in the main power supply system 10 while the vehicle power supply system 1 is in the on state. For example, ECU50 allows the vehicle V to drive automatically on the condition that a signal indicating that the backup low-voltage power supply 23 is in a state capable of supplying power to operate the important load 22 in an emergency is output from the backup power supply control device 25. Thus, even if an abnormality occurs in the main power supply system 10 during the automatic driving of the vehicle V, the backup low-voltage power supply 23 can reliably supply power to operate the important load 22 in an emergency, and the minimum driving operation, stopping operation or driving control required to safely move the vehicle V to the shoulder of the road and stop, namely the minimum risk strategy (MRM: Minimal Risk Maneuver), can be reliably executed.

[0203] Furthermore, if an abnormality occurs in the main power supply system 10 while the vehicle power supply system 1 is in the on state, the backup power supply system 20 is disconnected from the main power supply system 10, and power from the backup low-voltage power supply 23 is not supplied to the normal loads 12. This suppresses power consumption of the backup low-voltage power supply 23 while enabling operation of the critical loads 22 in an emergency.

[0204] Furthermore, since the first and third switches SW1 and SW3 are semiconductor switches, and the second switch SW2 is a DC-DC converter, the time required for the second switch SW2 to switch between the on and off states is longer than for the first and third switches SW1 and SW3. However, since the switching device 24 includes a capacitor CP as described above, the power stored in the capacitor CP is discharged between the time the first switch SW1 is switched off and the time the second switch SW2 is switched on. Therefore, power can be supplied to the critical emergency load 22 even after the first switch SW1 is switched off and the time the second switch SW2 is switched on.

[0205] Thus, when the vehicle power supply system 1 is in the on state, it performs an abnormality determination process to determine whether an abnormality has occurred in the main power supply system 10. This allows the vehicle power supply system 1 to constantly monitor whether an abnormality has occurred in the main power supply system 10 while in the on state, allowing the switching device 24 to be quickly activated if an abnormality occurs in the main power supply system 10. Conversely, when the vehicle power supply system 1 transitions from the off state to the on state, the backup power supply control device 25 outputs a signal indicating whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the critical emergency loads 22. This allows the vehicle power supply system 1 to be activated without constantly monitoring whether the backup low-voltage power supply 23 is in a state capable of supplying power to operate the critical emergency loads 22, thereby reducing power consumption.

[0206] While one embodiment of the present invention has been described above with reference to the accompanying drawings, it is needless to say that the present invention is not limited to this embodiment. Those skilled in the art will readily be able to devise various variations or modifications within the scope of the technical solution, and these variations or modifications naturally fall within the technical scope of the present invention. Furthermore, the various components of the above-described embodiments may be arbitrarily combined without departing from the spirit of the invention.

[0207] For example, the abnormality determination process for determining whether an abnormality has occurred in the main power supply system 10 as described in this embodiment is merely an example. The abnormality determination process may use any means or methods to determine whether an abnormality has occurred in the main power supply system 10. For example, a voltage sensor, a current sensor, or the like (not shown) may be provided in the main power supply system 10. The voltage and current of the main power supply system 10 may be estimated based on signals indicating the voltage and current values output by the voltage and current sensors. The process then determines whether the voltage and current of the main power supply system 10 are within a predetermined range. If the voltage and current of the main power supply system 10 are not within the predetermined range, the process determines that an abnormality has occurred in the main power supply system 10.

[0208] Furthermore, for example, in this embodiment, the switching device 24 includes a connection line L243 connected in parallel with the connection line L241, a first switch SW1 is provided on the connection line L241, and a third switch SW3 is provided on the connection line L243. However, the switching device 24 may not include the connection line L243, and a switch may be provided on the connection line L241 that combines the functions of the first switch SW1 and the third switch SW3 of this embodiment, replacing the first switch SW1 and the third switch SW3. Specifically, for example, the switch may have normally closed (NC) contacts, or the switch may remain in the on state and the connection line L241 may remain connected when no operating signal is applied to the switch. Furthermore, the switch may be an electromagnetic switch (e.g., an electromagnetic contactor or an electromagnetic switch) whose operating force is electromagnetic force, or the switch may remain in the on state and the connection line L241 may remain connected when no electromagnetic force is generated by the operating current. Furthermore, the switch may be, for example, a semiconductor switch. Furthermore, in the abnormality determination process, when it is determined that an abnormality has occurred in the main power supply system 10 , the backup power supply control device 25 switches the selector switch to the OFF state.

[0209] In addition, for example, in this embodiment, in step S130 (refer to Figure 2 ), the discharge amount Q of the backup low-voltage power supply 23 after the vehicle power supply system 1 is turned off is measured, and in step S240 (refer to Figure 3 ), it is determined whether the discharge amount Q of the backup low-voltage power supply 23 after the vehicle power supply system 1 is shut down is below the specified value Qset. However, steps S130 and S240 may be omitted. Thus, when the vehicle power supply system 1 is in the shut-down state, the power required to measure the discharge amount Q of the backup low-voltage power supply 23 is not consumed, thereby reducing power consumption when the vehicle power supply system 1 is in the shut-down state.

[0210] In addition, for example, in this embodiment, in step S120 (refer to Figure 2 ), obtain the temperature T0 of the backup low-voltage power supply 23 when the vehicle power supply system 1 is turned off, and in step S220 (refer to Figure 3 ), the temperature T of the backup low-voltage power supply 23 is obtained, and the temperature difference ΔT=|T-T0| is calculated based on the obtained temperature T of the backup low-voltage power supply 23 and the temperature T0 of the backup low-voltage power supply 23 when the vehicle power supply system 1 is shut down, which is obtained in step S120. Figure 3), a determination is made as to whether the temperature difference ΔT (=|T-T0|) obtained in step S220 is below a predetermined value Tset. However, steps S120, S220, and S230 may be omitted. Thus, when the vehicle power supply system 1 is in the off state, the temperature sensor for measuring the temperature T0 and the temperature T of the backup low-voltage power supply 23 is not required.

[0211] Furthermore, for example, in this embodiment, the second switch SW2 is a DC-DC converter, but the second switch SW2 only needs to be able to switch the connection line L242 between a connected state and a disconnected state. Therefore, the second switch SW2 can be any switch that can switch the connection line L242 between a connected state and a disconnected state, for example, a semiconductor switch having a normally open (NO) or normally closed (NC) contact.

[0212] In addition, for example, in this embodiment, in the switching device 24, a capacitor CP is provided on the connecting line L244, but in the switching device 24, for example, in a case where the second switch SW2 can be switched between the on state and the off state in a short time, the capacitor CP may not be provided on the connecting line L244.

[0213] This specification describes at least the following matters: Although corresponding components and the like in the above-described embodiment are shown in parentheses as an example, the present invention is not limited thereto.

[0214] (1) A vehicle power supply system (vehicle power supply system 1) mounted on a vehicle (vehicle V), comprising:

[0215] a main power supply system (main power supply system 10 ) having a main low-voltage power supply (main low-voltage power supply 11 ) and a normal load (normal load 12 ); and

[0216] A backup power supply system (backup power supply system 20) having a backup low-voltage power supply (backup low-voltage power supply 23) and an emergency important load (emergency important load 22) and connected to the main power supply system, wherein:

[0217] The backup power supply system is capable of supplying power from the backup low-voltage power supply to the main power supply system.

[0218] The backup power supply system comprises:

[0219] a switching device (switching device 24 ) capable of switching connection and disconnection with the main power supply system; and

[0220] A backup power supply control device (backup power supply control device 25), which controls the switching device,

[0221] The backup power supply control device is capable of executing a backup low-voltage power supply state estimation process, wherein the backup low-voltage power supply state estimation process estimates whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important load.

[0222] The backup power supply control device can output a signal indicating whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important load based on the estimation result of the backup low-voltage power supply state estimation process.

[0223] The backup power supply control device executes the backup low-voltage power supply state estimation process when the vehicle power supply system is in the off state and the state of the vehicle satisfies a predetermined condition.

[0224] According to (1), when the vehicle power supply system is in the off state and the state of the vehicle meets the specified conditions, the backup low-voltage power supply state estimation processing is performed to estimate whether the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency. Therefore, when the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency, when the vehicle power supply system changes from the off state to the on state, a signal indicating that the backup low-voltage power supply is in a state capable of supplying power to operate important loads in an emergency can be output in a short time.

[0225] (2) The vehicle power supply system according to (1), wherein

[0226] The predetermined condition includes that the time (elapsed time t) that has elapsed since the vehicle power supply system was last shut down is equal to or longer than a predetermined time (predetermined time tset).

[0227] According to (2), the backup low-voltage power supply state estimation processing is performed when the specified condition that the time elapsed since the vehicle power supply system was last shut down is longer than the specified time is met, thereby suppressing the power consumption when the vehicle power supply system is in the shut-down state, and when there is a high probability that the backup low-voltage power supply is not in a state where it can supply power to operate the important loads in an emergency due to the reduced remaining power of the backup low-voltage power supply due to the standby power of normal loads and important loads in an emergency, the backup low-voltage power supply state estimation processing can be performed.

[0228] (3) The vehicle power supply system according to (2), wherein

[0229] The specified conditions also include that the temperature difference (temperature difference ΔT) between the current temperature (temperature T) of the backup low-voltage power supply and the temperature (temperature T0) of the backup low-voltage power supply when the vehicle power supply system was most recently shut down is greater than a specified value (specified value Tset).

[0230] According to (3), the standby low-voltage power supply state estimation processing is performed when the specified condition is satisfied that the temperature difference between the temperature of the standby low-voltage power supply and the temperature of the standby low-voltage power supply when the vehicle power supply system was most recently shut down is greater than the specified value. Therefore, when there is a high probability that the temperature of the standby low-voltage power supply drops or rises sharply after the vehicle power supply system was most recently shut down and the standby low-voltage power supply is not in a state capable of supplying power to operate important loads in an emergency, the standby low-voltage power supply state estimation processing is performed. When there is a low probability that the standby low-voltage power supply is not in a state capable of supplying power to operate important loads in an emergency, the standby low-voltage power supply state estimation processing is not performed. Therefore, the power consumption when the vehicle power supply system is in the shut-down state can be further suppressed.

[0231] (4) The vehicle power supply system according to (2) or (3), wherein:

[0232] The predetermined condition further includes that a discharge amount (discharge amount Q) discharged from the backup low-voltage power supply since the vehicle power supply system was most recently shut down is equal to or greater than a predetermined value (predetermined value Qset).

[0233] According to (4), the standby low-voltage power supply state estimation processing is performed when the specified condition that the discharge amount of the standby low-voltage power supply since the vehicle power supply system was most recently shut down is greater than the specified value is met. Therefore, when there is a high probability that the discharge amount of the standby low-voltage power supply increases after the vehicle power supply system was most recently shut down and the standby low-voltage power supply is not in a state capable of supplying power to operate important loads in an emergency, the standby low-voltage power supply state estimation processing is performed. When there is a low probability that the standby low-voltage power supply is not in a state capable of supplying power to operate important loads in an emergency, the standby low-voltage power supply state estimation processing is not performed. Therefore, the power consumption when the vehicle power supply system is in the shut-down state can be further suppressed.

[0234] (5) The vehicle power supply system according to any one of (1) to (4), wherein

[0235] When an abnormality occurs in the main power supply system, the backup power supply control device controls the switching device to cut off the connection between the backup power supply system and the main power supply system, and supplies power from the backup low-voltage power supply to the emergency important load.

[0236] According to (5), if an abnormality occurs in the main power supply system, the backup power supply control device controls the switching device to supply power from the backup low-voltage power supply to the emergency important loads. Therefore, even if an abnormality occurs in the main power supply system when the vehicle power supply system is in the on state, the emergency important loads can be operated using the power of the backup low-voltage power supply, thereby enabling the vehicle to safely move to the shoulder of the road and stop, thereby enabling the minimum driving operation, stopping operation, or driving control required, i.e., the minimum risk maneuver (MRM), to be performed. Furthermore, when the vehicle power supply system transitions from the off state to the on state, the backup power supply control device outputs a signal indicating whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important loads. Therefore, based on the signal indicating whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important loads, the vehicle driving control can be performed. Thus, even if an abnormality occurs in the main power supply system when the vehicle power supply system is in the on state, power to operate the emergency important loads can be reliably supplied from the backup low-voltage power supply.

[0237] Furthermore, if an abnormality occurs in the main power supply system while the vehicle power supply system is on, the backup power supply system is disconnected from the main power supply system, preventing the supply of power from the backup low-voltage power supply to normal loads. This reduces power consumption in the backup low-voltage power supply while enabling critical emergency loads to operate.

[0238] (6) The vehicle power supply system according to any one of (1) to (5), wherein

[0239] When the vehicle power supply system is in an on state, the vehicle power supply system executes an abnormality determination process of determining whether an abnormality occurs in the main power supply system.

[0240] According to (6), when the vehicle power supply system is in the ON state, it is possible to constantly monitor whether an abnormality has occurred in the main power supply system, so that when an abnormality has occurred in the main power supply system, the switching device can be quickly activated.

[0241] (7) The vehicle power supply system according to any one of (1) to (6), wherein

[0242] The vehicle power supply system further comprises:

[0243] a high-voltage power supply system (high-voltage power supply system 30) including a high-voltage power supply (high-voltage power supply 31) that outputs power at a higher voltage than the main low-voltage power supply and the backup low-voltage power supply, and a high-voltage load (high-voltage load 32) that operates with power at a higher voltage than the normal load and the emergency critical load; and

[0244] a step-down device (step-down device 40 ) that steps down the voltage of the electric power flowing in the high-voltage power supply system,

[0245] The high-voltage power supply system is connected to the backup power supply system via the voltage reducing device.

[0246] The electric power of the high-voltage power supply can be used to charge the backup low-voltage power supply via the voltage step-down device.

[0247] According to (7), the backup low-voltage power supply can be charged with the electric power of the high-voltage power supply via the step-down device, thereby preventing the backup low-voltage power supply of the backup power supply system from being depleted.

Claims

1. A vehicle power supply system, mounted on a vehicle, comprising: a main power system having a main low voltage power source and typical loads; and A backup power supply system, which has a backup low-voltage power supply and important emergency loads, and is connected to the main power supply system, wherein: The backup power supply system is capable of supplying power from the backup low-voltage power supply to the main power supply system. The backup power supply system comprises: a switching device capable of switching connection and disconnection with the main power supply system; and A backup power supply control device, which controls the switching device, The backup power supply control device is capable of executing a backup low-voltage power supply state estimation process, wherein the backup low-voltage power supply state estimation process estimates whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important load. The backup power supply control device can output a signal indicating whether the backup low-voltage power supply is in a state capable of supplying power to operate the emergency important load based on the estimation result of the backup low-voltage power supply state estimation process. The backup power supply control device executes the backup low-voltage power supply state estimation process when the vehicle power supply system is in the off state and the state of the vehicle satisfies a prescribed condition. The predetermined condition includes that the time elapsed since the vehicle power supply system was last shut down is equal to or longer than a predetermined time.

2. The vehicle power supply system according to claim 1, wherein: The predetermined condition further includes that a temperature difference between a current temperature of the backup low-voltage power supply and a temperature of the backup low-voltage power supply when the vehicle power supply system was most recently shut down is greater than a predetermined value.

3. The vehicle power supply system according to claim 1 or 2, wherein: The predetermined condition further includes that the amount of discharge from the backup low-voltage power supply since the vehicle power supply system was most recently shut down is equal to or greater than a predetermined value.

4. The vehicle power supply system according to claim 1 or 2, wherein: When an abnormality occurs in the main power supply system, the backup power supply control device controls the switching device to cut off the connection between the backup power supply system and the main power supply system, and supplies power from the backup low-voltage power supply to the emergency important load.

5. The vehicle power supply system according to claim 1 or 2, wherein: When the vehicle power supply system is in an on state, the vehicle power supply system executes an abnormality determination process of determining whether an abnormality has occurred in the main power supply system.

6. The vehicle power supply system according to claim 1 or 2, wherein: The vehicle power supply system further comprises: a high-voltage power supply system comprising a high-voltage power supply and a high-voltage load, wherein the high-voltage power supply outputs power at a higher voltage than the main low-voltage power supply and the backup low-voltage power supply, and the high-voltage load operates with power at a higher voltage than the normal load and the emergency important load; and a step-down device for stepping down the voltage of the electric power flowing in the high-voltage power supply system, The high-voltage power supply system is connected to the backup power supply system via the voltage reducing device. The power of the high-voltage power supply can be used to charge the backup low-voltage power supply via the voltage step-down device.

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