Vehicle power supply system

Abstract

In a vehicle power supply system (1), a backup power supply device (30) has a backup 12V lithium battery (33) and a control ECU (36). Here, the load section (LD1), the load section (LD2), and the load section (LD3) are load sections having specific functions related to the vehicle. In this case, the load unit (LD3) is a load unit having other functions in addition to the specific function, and has, as the other functions, a discharge function for discharging power when the battery state of the backup 12V lithium battery (33) is estimated. The control ECU (36) can be switched to a normal mode, an abnormal mode, and a battery state estimation mode. The battery state estimation mode is a mode in which power is supplied from the standby 12V lithium battery (33) to the load unit (LD3) and the battery state of the standby 12V lithium battery (33) is estimated in a state in which power is not supplied from the main power supply device (20) to the load unit (LD3).

Description

Technical Field

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

[0002] In the past, as a vehicle power supply system, for example, Patent Document 1 describes a vehicle power supply system that includes: a main power supply device mounted on the vehicle and supplying power to a first load unit and a second load unit; and a backup power supply device mounted on the vehicle and supplying power to the second load unit when the main power supply device is abnormal. When the main power supply device is normal, the vehicle power supply system supplies power from the main power supply device to the first load unit and the second load unit, so that the vehicle can travel in a normal driving state, that is, in a normal mode. In addition, when the main power supply device is abnormal, the vehicle power supply system supplies power from the backup battery to the second load unit and does not supply power from the backup battery to the first load unit, so that the vehicle can travel in an abnormal mode, and the function of the abnormal mode is limited compared to the normal mode. The vehicle power supply system having such a normal mode and an abnormal mode estimates the battery state of the backup battery by discharging the power of the backup battery through a discharge circuit.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-35208 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, the vehicle power supply system described in Patent Document 1 described above is expected to suppress an increase in the number of components.

[0008] Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle power supply system capable of suppressing an increase in the number of components.

[0009] Means for solving problems

[0010] A vehicle power supply system, characterized in that it comprises: a main power supply device, which is mounted on the vehicle and supplies power to a first load unit, a second load unit, and a third load unit; and a backup power supply device, which is mounted on the vehicle and supplies power to at least the second load unit when the main power supply device is abnormal, the backup power supply device comprising: a backup battery, which stores the power supplied from the main power supply device and supplies power to at least the second load unit; and a control unit, which controls the power supplied from the main power supply device and the backup battery, the first load unit, the second load unit, and the third load unit are load units having specific functions related to the vehicle, and the third load unit is a load unit having other functions in addition to the specific functions, As the other function, it has a discharge function of discharging electric power when estimating the battery state of the backup battery, and the control unit is capable of switching between a normal mode, an abnormal mode, and a battery state estimation mode. The normal mode is a mode in which, when the main power supply unit is normal, electric power is supplied from the main power supply unit to at least the first load unit and the second load unit. The abnormal mode is a mode in which, when the main power supply unit is abnormal, electric power is supplied from the backup battery to at least the second load unit and electric power is not supplied from the backup battery to the first load unit. The battery state estimation mode is a mode in which, without supplying electric power from the main power supply unit to the third load unit, electric power is supplied from the backup battery to the third load unit and the battery state of the backup battery is estimated.

[0011] Effects of the Invention

[0012] In the vehicle power supply system of the present invention, the third load unit also serves as a load unit used when estimating the battery state of the backup battery. Therefore, dedicated load units for estimating the battery state can be reduced, resulting in an increase in the number of components. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a block diagram showing a configuration example of a vehicle power supply system according to an embodiment.

[0014] Figure 2 1 is a block diagram showing a normal mode of the vehicle power supply system according to the embodiment.

[0015] Figure 3 1 is a block diagram showing an abnormal mode of the vehicle power supply system according to the embodiment.

[0016] Figure 4 This is a block diagram showing a battery state estimation mode (part 1) of the vehicle power supply system according to the embodiment.

[0017] Figure 5This is a block diagram showing a battery state estimation mode (part 2) of the vehicle power supply system according to the embodiment.

[0018] Figure 6 This is a flowchart showing an operation example of the vehicle power supply system according to the embodiment.

[0019] Figure 7 It is a block diagram showing a configuration example of a vehicle power supply system according to a modification of the embodiment. DETAILED DESCRIPTION

[0020] The mode (embodiment) for implementing the present invention is described in detail with reference to the accompanying drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the constituent elements described below include elements that can be easily thought of by those skilled in the art, and substantially the same elements. Furthermore, the structures described below can be appropriately combined. In addition, various omissions, substitutions or changes in the structure can be made within the scope of the gist of the present invention.

[0021] The vehicle power supply system 1 of the embodiment will be described with reference to the drawings. The vehicle power supply system 1 is mounted on a vehicle and supplies power to a load unit of the vehicle. The load unit of the vehicle is configured to include, for example, a load unit LD1 as a first load unit, a load unit LD2 as a second load unit, and a load unit LD3 as a third load unit. The load unit LD1 is a device for allowing the occupants of the vehicle to spend time comfortably in the vehicle cabin, and is composed of, for example, a general load unit such as an audio system. The load unit LD2 is a device necessary for autonomous driving, and is composed of, for example, an autonomous driving load unit such as ADAS (Advanced Driver-Assistance Systems), brakes, door locks, and remote parking functions. The load unit LD3 is a device for allowing the occupants of the vehicle to spend time comfortably in the vehicle cabin, and is a device with a relatively large resistance, and is composed of, for example, a resistance-type load unit LD3a such as a heater having a heating function. The load unit LD3 has a switch circuit SW4 as a fourth switch circuit, and the switch circuit SW4 is provided between the main power supply device 20 described later and the resistance-type load unit LD3a. The vehicle power supply system 1 appropriately supplies power (also referred to as "DC power") to the load units LD1 to LD3. Figure 1 As shown, a high-voltage power supply system 10 , a main power supply device 20 , and a backup power supply device 30 are provided.

[0022] The high-voltage power supply system 10 constitutes a high-voltage power supply system, and includes a high-voltage battery 11, an inverter 12, and a motor 13. The high-voltage battery 11 supplies charged power (DC power) to the inverter 12. The inverter 12 is connected to the high-voltage battery 11, converts the power (DC power) supplied from the high-voltage battery 11 into AC power, and supplies the converted AC power to the motor 13. The motor 13 is a motor for driving, and is connected to the inverter 12. The motor 13 is driven by the power supplied from the inverter 12 to drive the vehicle.

[0023] The main power supply device 20 supplies electric power to the load unit LD1 , the load unit LD2 , and the load unit LD3 . The main power supply device 20 includes a high-voltage DC / DC converter 21 , a 12V lead battery 22 , and a power supply management ECU 23 .

[0024] The high-voltage DC / DC converter 21 transforms the DC voltage. The high-voltage DC / DC converter 21 steps down the voltage of the DC power output from the high-voltage battery 11, for example, to a voltage of 12V on the spot. The high-voltage DC / DC converter 21 is connected to the 12V lead battery 22, and charges the 12V lead battery 22 with the stepped-down DC power. In addition, the high-voltage DC / DC converter 21 is connected to the load unit LD1, and is connected to the load units LD2 and LD3 via the backup power supply device 30. The high-voltage DC / DC converter 21 supplies power of 12V voltage to the load unit LD1, and supplies power of 12V voltage to the load units LD2 and LD3 via the backup power supply device 30.

[0025] The 12V lead battery 22 is a component for storing power, such as a lead storage battery. The 12V lead battery 22 is connected to the high-voltage DC / DC converter 21, and stores the DC power obtained by stepping down the voltage of the high-voltage DC / DC converter 21. The 12V lead battery 22 is connected to the load unit LD1, and is connected to the load units LD2 and LD3 via the backup power supply device 30. The 12V lead battery 22 supplies power to the load unit LD1, and supplies power to the load units LD2 and LD3 via the backup power supply device 30.

[0026] The power management ECU 23 controls the high-voltage power supply system 10 and the high-voltage DC / DC converter 21. The power management ECU 23 is configured to include an electronic circuit mainly including a well-known microcomputer including a CPU, a storage unit, and an interface. The power management ECU 23 controls the high-voltage power supply system 10 based on a control program stored in the storage unit. The power management ECU 23 monitors the power storage state of the 12V lead battery 22 and controls the high-voltage DC / DC converter 21 according to the power storage state of the 12V lead battery 22. For example, when the power storage rate of the 12V lead battery 22 is less than a predetermined reference value, the power management ECU 23 increases the output voltage of the high-voltage DC / DC converter 21 and charges the 12V lead battery 22. On the other hand, when the power storage rate of the 12V lead battery 22 is greater than the reference value, the power management ECU 23 reduces the output voltage of the high-voltage DC / DC converter 21 to maintain the power storage rate of the 12V lead battery 22.

[0027] The backup power supply device 30 replaces the main power supply device 20 to supply power to the load unit LD2 when the main power supply device 20 is abnormal, such as a ground fault. The backup power supply device 30 is connected to the main power supply device 20 and the load units LD2 and LD3 via a connector (not shown), for example. The backup power supply device 30 is connected to the load units LD2 and LD3 via a fuse F. The backup power supply device 30 includes a housing 31, a 12V DC / DC converter 32, a backup 12V lithium battery 33 as a backup battery, a switch unit 34, a detection unit 35, and a control ECU 36 as a control unit.

[0028] The housing 31 accommodates various electronic components. The housing 31 is formed in a box shape with a heat dissipation function. The housing 31 is independently configured from the main power supply device 20. The housing 31 accommodates a 12V DC / DC converter 32, a switch unit 34, and a control ECU 36 in its internal space. In addition, a backup 12V lithium battery 33 is externally mounted on the housing 31, but the backup 12V lithium battery 33 may also be accommodated in the internal space.

[0029] The 12VDC / DC converter 32 transforms the DC voltage. The 12VDC / DC converter 32 is connected to the high-voltage DC / DC converter 21 via the switch unit 34 (switch circuit SW1). When the backup 12V lithium battery 33 needs to be charged, the 12VDC / DC converter 32 receives the DC power that has been transformed from high voltage to low voltage and output by the high-voltage DC / DC converter 21, and boosts the voltage to a voltage higher than the terminal voltage of the backup 12V lithium battery 33. The 12VDC / DC converter 32 is connected to the backup 12V lithium battery 33, and charges the backup 12V lithium battery 33 with the boosted DC power.

[0030] The backup 12V lithium battery 33 is a component that stores power, such as a lithium-ion battery. The backup 12V lithium battery 33 is connected to the 12VDC / DC converter 32, and stores the DC power boosted by the 12VDC / DC converter 32. The backup 12V lithium battery 33 is connected to the load unit LD2 and the load unit LD3 via the switch unit 34 (switch circuit SW2), and supplies the stored DC power to the load unit LD2 and the load unit LD3. In addition, the backup 12V lithium battery 33 is connected to the load unit LD3 via the switch unit 34 (switch circuit SW3), and supplies the stored DC power to the load unit LD3. The load unit LD3 has a path connected to the switch circuit SW2 via the switch circuit SW3.

[0031] The switch unit 34 conducts or blocks current and is configured to include a switch circuit SW1 as a first switch circuit, a switch circuit SW2 as a second switch circuit, and a switch circuit SW3 as a third switch circuit.

[0032] The switch circuit SW1 is provided between the main power supply device 20 and the backup power supply device 30, and switches the connection between the main power supply device 20 and the backup power supply device 30. For example, the switch circuit SW1 is located between the high-voltage DC / DC converter 21 and the 12VDC / DC converter 32, and switches the connection between the high-voltage DC / DC converter 21 and the 12VDC / DC converter 32. The switch circuit SW1 energizes the current path connecting the high-voltage DC / DC converter 21 and the 12VDC / DC converter 32 by turning on, and cuts off the current path connecting the high-voltage DC / DC converter 21 and the 12VDC / DC converter 32 by turning off. In addition, the switch circuit SW1 is located between the high-voltage DC / DC converter 21 and the load parts LD2 and LD3, and switches the connection between the high-voltage DC / DC converter 21 and the load parts LD2 and LD3. The switch circuit SW1 energizes the current path connecting the high-voltage DC / DC converter 21 and the load parts LD2 and LD3 by turning on, and cuts off the current path connecting the high-voltage DC / DC converter 21 and the load parts LD2 and LD3 by turning off. In addition, the switch circuit SW1 is located between the 12V lead battery 22 and the load parts LD2 and LD3, and switches the connection between the 12V lead battery 22 and the load parts LD2 and LD3. The switch circuit SW1 energizes the current path connecting the 12V lead battery 22 and the load parts LD2 and LD3 by turning on, and cuts off the current path connecting the 12V lead battery 22 and the load parts LD2 and LD3 by turning off.

[0033] For example, when the main power supply device 20 and the backup power supply device 30 are normal, the switch circuit SW1 is turned on based on the on signal output from the control ECU 36, and the current path connecting the main power supply device 20 and the backup power supply device 30 is energized. On the other hand, when the main power supply device 20 or the backup power supply device 30 is abnormal, the switch circuit SW1, although not shown in the figure, can receive the output of the circuit detecting the abnormality and turn off, and turn off based on the disconnection signal output from the control ECU 36, and cut off the current path connecting the main power supply device 20 and the backup power supply device 30.

[0034] The switch circuit SW2 is provided between the backup 12V lithium battery 33 and the load unit LD2 and the load unit LD3, and switches the connection between the backup 12V lithium battery 33 and the load unit LD2 and the load unit LD3. The switch circuit SW2 energizes the current path connecting the backup 12V lithium battery 33 and the load unit LD2 and the load unit LD3 by turning on, and cuts off the current path connecting the backup 12V lithium battery 33 and the load unit LD2 and the load unit LD3 by turning off.

[0035] For example, when the main power supply device 20 and the backup power supply device 30 are normal, the switch circuit SW2 is disconnected based on the disconnection signal output from the control ECU 36, and the current path connecting the backup 12V lithium battery 33 and the load part LD2 and the load part LD3 is cut off. On the other hand, when the main power supply device 20 is abnormal, the switch circuit SW2, although not shown in the figure, can receive the output of the circuit for detecting the abnormality and turn on, and is turned on based on the connection signal output from the control ECU 36, so that the current path connecting the backup 12V lithium battery 33 and the load part LD2 and the load part LD3 is energized.

[0036] The switch circuit SW3 is provided between the backup 12V lithium battery 33 and the load unit LD3, and switches the connection between the backup 12V lithium battery 33 and the load unit LD3. The switch circuit SW3 energizes the current path connecting the backup 12V lithium battery 33 and the load unit LD3 by turning on, and cuts off the current path connecting the backup 12V lithium battery 33 and the load unit LD3 by turning off.

[0037] For example, when estimating the battery state of the backup 12V lithium battery 33, the switch circuit SW3 is turned on based on the on signal output from the control ECU 36, and the current path connecting the backup 12V lithium battery 33 and the load unit LD3 is energized. On the other hand, when not estimating the battery state of the backup 12V lithium battery 33, the switch circuit SW3 is turned off based on the off signal output from the control ECU 36, and the current path connecting the backup 12V lithium battery 33 and the load unit LD3 is cut off.

[0038] The detection unit 35 detects current and voltage, and includes a current sensor 35a and a voltage sensor 35b. The current sensor 35a detects the current flowing through the resistance load unit LD3a of the load unit LD3. The current sensor 35a outputs the detected current value to the control ECU 36. The voltage sensor 35b detects the voltage applied to the resistance load unit LD3a of the load unit LD3. The voltage sensor 35b outputs the detected voltage value to the control ECU 36.

[0039] The control ECU 36 controls the 12VDC / DC converter 32 and the switch unit 34. The control ECU 36 is configured as an electronic circuit mainly including a well-known microcomputer including a CPU, a storage unit, and an interface. The control ECU 36 monitors the power storage state of the backup 12V lithium battery 33 based on the control program stored in the storage unit, for example, and controls the 12VDC / DC converter 32 according to the power storage state of the backup 12V lithium battery 33. For example, when the power storage rate of the backup 12V lithium battery 33 is less than a predetermined reference value, the control ECU 36 increases the output voltage of the 12VDC / DC converter 32 to charge the backup 12V lithium battery 33. On the other hand, when the power storage rate of the backup 12V lithium battery 33 is greater than the reference value, the control ECU 36 stops the output voltage of the 12VDC / DC converter 32 and maintains the power storage rate of the backup 12V lithium battery 33.

[0040] In addition, when the main power supply device 20 and the backup power supply device 30 are normal, the control ECU 36 drives the vehicle in the normal mode. Here, the normal mode refers to a normal driving state, for example, the 12V lead battery 22 and the backup 12V lithium battery 33 are both in a normal state, and it is a mode in which at least the load parts LD1 and LD2 are operated. In this example, the load parts LD1, LD2, and LD3 are operated. In the normal mode, the control ECU 36 outputs an on signal to the switch circuit SW1 to energize the current path connecting the main power supply device 20 and the backup power supply device 30, and the switch circuit SW4 is arbitrarily operated by the vehicle system or the driver to output an on signal or an off signal. When the on signal is output, the current path connecting the main power supply device 20 and the resistance load part LD3a is energized. In addition, in the normal mode, the control ECU 36 outputs a disconnection signal to the switch circuit SW2 to cut off the current path connecting the backup 12V lithium battery 33 with the load unit LD2 and the load unit LD3, and outputs a disconnection signal to the switch circuit SW3 to cut off the current path connecting the backup 12V lithium battery 33 with the load unit LD3, so that the 12VDC / DC converter 32 is disconnected. Figure 2As shown, the control ECU 36 can make the load current I1 flow from the high-voltage DC / DC converter 21 or the 12V lead battery 22 to the load parts LD1, LD2, and LD3. In addition, when the switch circuit SW4 outputs a disconnection signal, it cuts off the current path connecting the main power supply device 20 and the resistance load part LD3a. In this case, the load current I1 flows from the high-voltage DC / DC converter 21 or the 12V lead battery 22 to the load parts LD1 and LD2, and the load current I1 does not flow to the load part LD3.

[0041] On the other hand, when the main power supply device 20 is abnormal due to a ground fault or the like, the control ECU 36 causes the vehicle to travel in an abnormal mode. Here, the abnormal mode refers to a driving state when an abnormality occurs, for example, a mode in which the main power supply device 20 is in an abnormal state and the load unit LD2 operates while the load units LD1 and LD3 do not operate. In this way, the abnormal mode is a mode in which the functions of the vehicle are limited compared to the normal mode. Even in this abnormal mode, the vehicle can be automatically driven by automatic driving or the like, for example, it can be automatically driven in the abnormal mode to a place where the safety of the vehicle is ensured.

[0042] In the case of abnormal mode, the control ECU 36 outputs a disconnect signal to the switch circuit SW1 to cut off the current path connecting the main power supply device 20 and the backup power supply device 30, and outputs a disconnect signal to the switch circuit SW3 to cut off the current path connecting the backup 12V lithium battery 33 and the load part LD3. In addition, in the case of abnormal mode, the control ECU 36 outputs a connection signal to the switch circuit SW2 to energize the current path connecting the backup 12V lithium battery 33 and the load parts LD2 and LD3. The switch circuit SW4 is arbitrarily operated by the vehicle system or the driver to output an on signal or an off signal. When the on signal is output, the load part LD3 is turned on, and when the off signal is output, the load part LD3 is turned off. However, it is conceivable that the load part LD3 is preferentially disconnected in an abnormality, and thus, Figure 3 As shown, the control ECU 36 can make the load current I2 flow from the backup 12V lithium battery 33 to the load part LD2 while isolating the main power supply device 20 from the backup power supply device 30. At this time, the control ECU 36 does not supply power from the backup 12V lithium battery 33 to the load part LD1, and for the load part LD3, there is a situation where power is supplied or not supplied according to the operation of the vehicle system or the driver.

[0043] Here, as described above, the load unit LD1 is composed of a general load unit such as an audio system, the load unit LD2 is composed of a load unit for automatic driving such as ADAS, and the load unit LD3 is composed of a resistance load unit LD3a such as a heater. Moreover, the load unit LD1, the load unit LD2, and the load unit LD3 are load units having specific functions related to the vehicle. In this case, the load unit LD3 is different from the load units LD1 and LD2, and is a load unit having other functions in addition to the specific functions. As other functions, the load unit LD3 has a discharge function that discharges power when estimating the battery state of the backup 12V lithium battery 33. Specifically, the load unit LD3 is used as both a resistance load unit LD3a such as a heater as a specific function and a load unit (discharge circuit) that discharges power when estimating the battery state as other functions. In other words, the load unit LD3 is not a dedicated load unit that discharges power when estimating the battery state, but has other functions as a load unit in addition to the discharge function when estimating the battery state.

[0044] The control ECU 36 has a battery state estimation mode. The battery state estimation mode is a mode in which power is supplied from the backup 12V lithium battery 33 to the load unit LD3 in a state in which power is not supplied from the main power supply unit 20 to the load unit LD3, and the battery state of the backup 12V lithium battery 33 is estimated. The control ECU 36 switches to the battery state estimation mode for estimating the battery state of the backup 12V lithium battery 33 at a predetermined timing. The control ECU 36 switches to the battery state estimation mode, for example, when the main power supply unit 20 is disconnected, such as when the vehicle is parked, or when the ACC (accessory) power supply or IG (ignition) power supply of the vehicle is turned on and the main power supply unit 20 is turned on. In a case in which the control ECU 36 switches to the battery state estimation mode, for example, when the main power supply unit 20 is disconnected, such as when the vehicle is parked, Figure 4 As shown, an on signal is output to the switch circuit SW3 and an off signal is output to the switch circuits SW1 and SW2, so that the current path connecting the backup 12V lithium battery 33 and the load unit LD3 is energized. At this time, the switch circuit SW4 is turned off. As a result, the control ECU 36 can make the discharge current I3 flow from the backup 12V lithium battery 33 to the load unit LD3.

[0045] In addition, when the ACC (accessory) power supply or the IG (ignition) power supply of the vehicle is turned on and the main power supply device 20 is turned on, the control ECU 36 switches to the battery state estimation mode. Figure 5As shown, an on signal is output to the switch circuits SW1 and SW3 and an off signal is output to the switch circuit SW2, so that the current path connecting the high-voltage DC / DC converter 21 and the 12V lead battery 22 and the load parts LD1, LD2, and LD3 is energized, and the current path connecting the backup 12V lithium battery 33 and the load part LD3 is energized. At this time, SW4 is disconnected through the vehicle system. As a result, the control ECU 36 can make the load current I1 flow to the load parts LD1 and LD2, and make the discharge current I3 flow from the backup 12V lithium battery 33 to the load part LD3.

[0046] When the control ECU 36 estimates the deterioration state of the backup 12V lithium battery 33 in the battery state estimation mode, the internal resistance of the backup 12V lithium battery 33 is obtained based on the current value output from the current sensor 35a and the voltage value output from the voltage sensor 35b. Then, the control ECU 36 estimates the deterioration state of the backup 12V lithium battery 33 based on the obtained internal resistance of the backup 12V lithium battery 33. Here, the deterioration state represents the degree (level) of deterioration of the backup 12V lithium battery 33. The degree (level) of deterioration is estimated based on the internal resistance of the backup 12V lithium battery 33. For example, when the internal resistance of the backup 12V lithium battery 33 is greater than a predetermined reference resistance, the control ECU 36 estimates that the backup 12V lithium battery 33 is in an abnormal state with a high degree of deterioration. On the other hand, when the internal resistance of the backup 12V lithium battery 33 is less than the reference resistance, the control ECU 36 estimates that the degree of deterioration of the backup 12V lithium battery 33 is low and not in an abnormal state.

[0047] Next, an operation example of the vehicle power supply system 1 will be described. Figure 6 As shown, the control ECU 36 determines whether it is in the battery state estimation mode (step S1). When the control ECU 36 switches to the battery state estimation mode when the main power supply device 20 is disconnected, such as when the vehicle is parked (step S1; yes), the backup 12V lithium battery 33 supplies power to the resistance load part LD3a as a heater with a heating function (step S2). Figure 4As shown, the control ECU 36 outputs an on signal to the switch circuit SW3 and an off signal to the switch circuits SW1 and SW2, so that the current path connecting the backup 12V lithium battery 33 and the load unit LD3 is energized, and power is supplied from the backup 12V lithium battery 33 to the resistance load unit LD3a, and the backup 12V lithium battery 33 is discharged through the resistance of the load unit LD3 as a heater. At this time, the switch circuit SW4 is turned off. In the battery state estimation mode, for example, the backup 12V lithium battery 33 is discharged through the resistance of the load unit LD3 for a period of several seconds to several tens of seconds. Next, the control ECU 36 estimates the battery state of the backup 12V lithium battery 33 (step S3). The control ECU 36 obtains the internal resistance of the backup 12V lithium battery 33 based on the current value output from the current sensor 35a and the voltage value output from the voltage sensor 35b. Then, the control ECU 36 estimates the battery state of the backup 12V lithium battery 33 based on the obtained internal resistance of the backup 12V lithium battery 33. In addition, in the above-mentioned step S1, when the control ECU 36 has not switched to the battery state estimation mode (step S1; No), it determines again whether it is the battery state estimation mode.

[0048] As described above, the vehicle power supply system 1 according to the embodiment includes a main power supply device 20 and a backup power supply device 30. The main power supply device 20 is mounted on the vehicle and supplies power to the load unit LD1, the load unit LD2, and the load unit LD3. The backup power supply device 30 is mounted on the vehicle and supplies power to at least the load unit LD2 when the main power supply device 20 is abnormal. The backup power supply device 30 includes: a backup 12V lithium battery 33 that stores the power supplied from the main power supply device 20 and supplies power to at least the load unit LD2; and a control ECU 36 that controls the power supplied from the main power supply device 20 and the backup 12V lithium battery 33. Here, the load unit LD1, the load unit LD2, and the load unit LD3 are load units having specific functions related to the vehicle. In this case, the load unit LD3 is a load unit having other functions in addition to the specific functions, and as other functions, has a discharge function of discharging power when estimating the battery state of the backup 12V lithium battery 33. The control ECU 36 can switch between a normal mode, an abnormal mode, and a battery state estimation mode. The normal mode is a mode in which power is supplied from the main power supply device 20 to at least the load unit LD1 and the load unit LD2 when the main power supply device 20 is normal. The abnormal mode is a mode in which power is supplied from the backup 12V lithium battery 33 to at least the load unit LD2 and power is not supplied from the backup 12V lithium battery 33 to the load unit LD1 when the main power supply device 20 is abnormal. The battery state estimation mode is a mode in which power is supplied from the backup 12V lithium battery 33 to the load unit LD3 and the battery state of the backup 12V lithium battery 33 is estimated in a state in which power is not supplied from the main power supply device 20 to the load unit LD3.

[0049] According to this structure, in the vehicle power supply system 1, the load unit LD3 is also used as a load unit used when estimating the battery state of the backup 12V lithium battery 33, so that the dedicated load unit (discharge circuit) for estimating the battery state can be reduced. As a result, the vehicle power supply system 1 can suppress the increase in the number of components and can suppress the large-scale, thereby reducing costs. In addition, the vehicle power supply system 1 does not provide a heat dissipation circuit for estimating the battery state in the backup power supply device 30, so it is possible to suppress the situation of increasing the spacing between components in consideration of heat dissipation, and can reduce the mounting area to more than the area occupied by a single component.

[0050] In the above-mentioned vehicle power supply system 1, the backup power supply device 30 has a switch circuit SW1 for switching the connection with the main power supply device 20, a switch circuit SW2 for switching the connection between the backup 12V lithium battery 33 and the load unit LD2, and a switch circuit SW3 for switching the connection between the backup 12V lithium battery 33 and the load unit LD3. The load unit LD3 has a switch circuit SW4 for switching the connection with the main power supply device 20. When the main power supply device 20 is normal, the control ECU 36 turns on the switch circuit SW1 and turns off the switch circuit SW2 and the switch circuit SW3, thereby switching to the normal mode. At this time, the switch circuit SW4 is arbitrarily controlled by the vehicle system or the driver. When the main power supply device 20 is abnormal, the control ECU 36 turns on the switch circuit SW2 and turns off the switch circuit SW1 and the switch circuit SW3, thereby switching to the abnormal mode. When estimating the battery state of the backup 12V lithium battery 33, the control ECU 36 turns on the switch circuit SW3 and turns off the switch circuit SW2 in the state where the fourth switch circuit SW4 is turned off, thereby switching to the battery state estimation mode. In this way, the vehicle power supply system 1 can switch between the normal mode, the abnormal mode, and the battery state estimation mode as appropriate by switching each switch circuit.

[0051] In the vehicle power supply system 1, the load unit LD3 is a heater having a heating function as a specific function. In the case of the battery state estimation mode, the control ECU 36 discharges the backup 12V lithium battery 33 through the resistance of the load unit LD3 as a heater. According to this structure, the vehicle power supply system 1 can use a heater with a relatively large resistance as a discharge circuit when estimating the battery state, so that the power of the backup 12V lithium battery 33 can be fully discharged, and the internal resistance of the backup 12V lithium battery 33 can be appropriately calculated.

[0052] In addition, in the above description, the backup power supply device 30 has a switch circuit SW1, a switch circuit SW2, and a switch circuit SW3, and the load unit LD3 has a switch circuit SW4. Each mode is switched by switching each switch circuit, but the structure of the switch circuit that switches to each mode is not limited to the above, and may also be a structure of other switch circuits. For example, the switch circuit SW4 is a switch that can be operated by a user such as a vehicle system or a driver, but it can also be controlled in a way that the switch is automatically disconnected when the battery state estimation is performed, and the switch setting is returned to the previous state after the battery state estimation is completed. The switch circuit SW4 can be within the control range of the control ECU 36 of the backup power supply device 30, or it can be outside the control range of the control ECU 36.

[0053] Furthermore, although the example in which the load portion LD3 is a heater has been described, the present invention is not limited to this and may be another load portion.

[0054] In addition, the housing 31 is formed as a separate body that does not accommodate the power distribution unit and the fuse F in its internal space, but is not limited to this. Figure 7 In the vehicle power supply system 1A shown, the housing 31A accommodates the power distribution unit and the fuse F in its internal space, and the power distribution unit and the fuse F are integrated as a unit. According to this structure, the vehicle power supply system 1A can miniaturize the components of the connector and the bolt fastening part, and can suppress the increase in the number of these components. In addition, the vehicle power supply system 1A can also shorten the length of the connection path of the cable etc. connecting the components.

[0055] In addition, the load unit LD1 and the load unit LD2 may also be configured to include devices that are combined with each other to form an actuator. For example, the load unit LD1 includes a first steering device, and the load unit LD2 includes a second steering device. Moreover, the load unit LD1 and the load unit LD2 combine the first steering device and the second steering device to form an actuator (steering device). The actuator performs normal operation (normal mode) by operating the device of the load unit LD1 and the device of the load unit LD2. In addition, the actuator performs limited operation (abnormal mode) in which the function is limited compared to normal operation by making the device of the load unit LD1 inoperative and the device of the load unit LD2 operative. According to this structure, the vehicle power supply system 1 can drive the vehicle to a place where the safety of the vehicle can be ensured even when the main power supply device 20 is abnormal.

[0056] In addition, the battery state estimation mode is described as estimating the deterioration state of the backup 12V lithium battery 33, but it can also estimate states other than the deterioration state. For example, the battery state estimation mode can estimate the charge capacity, abnormal state, or estimate other battery states together with the deterioration state.

[0057] Description of Reference Numerals

[0058] 1Vehicle power system

[0059] LD1 load part (first load part)

[0060] LD2 load part (second load part)

[0061] LD3 load part (third load part)

[0062] 20 Main power supply unit

[0063] 30 Backup power supply unit

[0064] 33 Spare 12V lithium battery (spare battery)

[0065] 36 Control ECU (control unit)

[0066] SW1 switch circuit (first switch circuit)

[0067] SW2 switch circuit (second switch circuit)

[0068] SW3 switch circuit (third switch circuit)

[0069] SW4 switch circuit (fourth switch circuit)

Claims

1. A vehicle power supply system, characterized in that: have: a main power supply device mounted on the vehicle and supplying electric power to the first load unit, the second load unit, and the third load unit; and a backup power supply device mounted on the vehicle and supplying power to at least the second load unit when the main power supply device fails, The backup power supply device includes: a backup battery that stores power supplied from the main power supply device and supplies power to at least the second load unit; and a control unit that controls the power supplied from the main power supply device and the backup battery. The first load unit, the second load unit, and the third load unit are load units having specific functions related to the vehicle. The third load unit is a load unit having other functions in addition to the specific function, and has, as the other function, a discharge function of discharging electric power when estimating the battery state of the backup battery, The control unit is capable of switching between a normal mode, an abnormal mode, and a battery state estimation mode. The normal mode is a mode in which, when the main power supply device is normal, power is supplied from the main power supply device to at least the first load unit and the second load unit. The abnormal mode is a mode in which, when the main power supply device is abnormal, power is supplied from the backup battery to at least the second load unit and power is not supplied from the backup battery to the first load unit. The battery state estimation mode is a mode in which power is supplied from the backup battery to the third load unit while power is not supplied from the main power supply device to the third load unit, and the battery state of the backup battery is estimated.

2. The vehicle power supply system according to claim 1, characterized in that: The backup power supply device comprises: a first switch circuit, the first switch circuit switches the connection between the backup power supply device and the main power supply device; a second switch circuit, the second switch circuit switches the connection between the backup battery and the second load unit; and a third switch circuit, the third switch circuit switches the connection between the backup battery and the third load unit. The third load unit includes a fourth switch circuit, and the fourth switch circuit switches the connection between the third load unit and the main power supply device. When the main power supply device is normal, the control unit switches to the normal mode by turning on the first switch circuit and turning off the second switch circuit and the third switch circuit. When the main power supply device is abnormal, the control unit switches to the abnormal mode by turning on the second switch circuit and turning off the first switch circuit and the third switch circuit. When estimating the battery state of the backup battery, the control unit switches to the battery state estimation mode by turning on the third switch circuit and turning off the second switch circuit while the fourth switch circuit is turned off.

3. The vehicle power supply system according to claim 1 or 2, characterized in that: The third load unit is a heater having a heating function as the specific function, The control unit discharges the backup battery through the resistance of the third load unit serving as the heater in the battery state estimation mode.

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