Vehicle power supply system

Abstract

To provide a vehicle power system that can prevent an increase in the number of components.SOLUTION: In a vehicle power system 1, a backup power device 30 has a 12 V LI battery 33 for backup and a control ECU 36. Here, a load part LD1, a load part LD2, and a load part LD3 are a load part having a specific function related to a vehicle. In this case, the load part LD3 is a load part having another function in addition to the specific function, and as the another function, has a discharge function of discharging electric power in estimating the battery state of the 12 V LI battery 33 for backup. The control ECU 36 can be switched between a normal mode, an abnormal mode, and a battery state estimation mode. The battery state estimation mode is a mode for supplying electric power from the 12 V LI battery 33 for backup to the load part LD3 in a state where electric power is not supplied from a main power device 20 to the load part LD3, and estimating the battery state of the 12 V LI battery 33 for backup.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as a vehicle power supply system, for example, Patent Document 1 describes a vehicle power supply system including a main power supply device mounted on a vehicle that supplies power to a first load unit and a second load unit, and a backup power supply device mounted on the vehicle that supplies power to the second load unit when the main power supply device is abnormal. When the main power supply device is normal, this vehicle power supply system supplies power from the main power supply device to the first load unit and the second load unit, enabling the vehicle to run in a normal mode which is a normal operating state. Also, 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, enabling the vehicle to run in an abnormal mode with restricted functions compared to the normal mode. Such a vehicle power supply system having a normal mode and an abnormal mode discharges the power of the backup battery by a discharge circuit and estimates the battery state of the backup battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, it is desired to suppress an increase in the number of components in the vehicle power supply system described in Patent Document 1 above.

[0005] Therefore, the present invention has been made in view of the above, and an object thereof is to provide a vehicle power supply system capable of suppressing an increase in the number of components.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, a vehicle power supply system according to the present invention includes a main power supply device mounted on a vehicle that supplies power to a first load unit, a second load unit, and a third load unit, and a backup power supply device mounted on the vehicle that supplies power to at least the second load unit when the main power supply device is abnormal. 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 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 functions. As the other function, it has a discharge function of discharging power when estimating the battery state of the backup battery. The control unit can switch between a normal mode in which power is supplied from the main power supply device to at least the first load unit and the second load unit when the main power supply device is normal, an abnormal mode in which 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 when the main power supply device is abnormal, and a battery state estimation mode in which power is supplied from the backup battery to the third load unit to estimate the battery state of the backup battery in a state where power is not supplied from the main power supply device to the third load unit.

Advantages of the Invention

[0007] In the vehicle power supply system according to the present invention, since the third load unit also serves as a load unit used when estimating the battery state of the backup battery, a dedicated load unit for estimating the battery state can be reduced. As a result, an increase in the number of components can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Also, the constituent elements described below include those that can be easily assumed by those skilled in the art and substantially the same ones. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0010] The vehicle power supply system 1 according to 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 the load section of the vehicle. The load section of the vehicle includes, for example, a load section LD1 as a first load section, a load section LD2 as a second load section, and a load section LD3 as a third load section. The load section LD1 is equipment for the vehicle occupants to comfortably spend time in the vehicle interior, and is composed of, for example, a general load section such as an audio system. The load section LD2 is equipment necessary for autonomous driving and the like, and is composed of, for example, an autonomous driving load section such as ADAS (Advanced Driver-Assistance Systems), brakes, door locks, and remote parking functions. The load section LD3 is equipment for the vehicle occupants to comfortably spend time in the vehicle interior and has a relatively large electrical resistance. For example, it is composed of a resistive load section LD3a such as a heater having a heating function. The load section 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 and the resistive load section LD3a described later. The vehicle power supply system 1 appropriately supplies power (also referred to as "DC power") to the load sections LD1 to LD3, and as shown in FIG. 1, includes a high-voltage power supply system 10, a main power supply device 20, and a backup power supply device 30.

[0011] 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 the 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 make the vehicle run.

[0012] The main power supply device 20 supplies power to the load section LD1, the load section LD2, and the load section LD3. The main power supply device 20 has a high-voltage DC / DC converter 21, a 12V lead battery 22, and a power management ECU 23.

[0013] The high-voltage DC / DC converter 21 transforms DC voltage. The high-voltage DC / DC converter 21 steps down the voltage of the DC power output from the high-voltage battery 11 and steps it down to, for example, 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. Also, 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.

[0014] The 12V lead battery 22 stores electric power and is, for example, a lead-acid battery. The 12V lead battery 22 is connected to the high-voltage DC / DC converter 21 and stores the DC power stepped down by 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.

[0015] 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 includes an electronic circuit mainly composed of 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 state of charge of the 12V lead battery 22 and controls the high-voltage DC / DC converter 21 according to the state of charge of the 12V lead battery 22. For example, when the state of charge 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 to charge the 12V lead battery 22. On the other hand, when the state of charge of the 12V lead battery 22 is equal to or higher than the reference value, the power management ECU 23 decreases the output voltage of the high-voltage DC / DC converter 21 to maintain the state of charge of the 12V lead battery 22.

[0016] The backup power supply device 30 supplies power to the load unit LD2 in place of the main power supply device 20 in case of an abnormality such as a ground fault in the main power supply device 20. 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 LI battery 33 as a backup battery, a switch unit 34, a detection unit 35, and a control ECU 36 as a control unit.

[0017] The housing 31 houses various electronic components. The housing 31 is formed in a box shape with a heat dissipation function. The housing 31 is configured separately from the main power supply device 20. The housing 31 houses the 12V DC / DC converter 32, the switch unit 34, and the control ECU 36 in its internal space. Although the backup 12V LI battery 33 is externally attached to the housing 31, the backup 12V LI battery 33 may be housed in the internal space.

[0018] The 12V DC / DC converter 32 transforms DC voltage. The 12V DC / DC converter 32 is connected to the high-voltage DC / DC converter 21 via a switch unit 34 (switch circuit SW1). When the backup 12V LI battery 33 needs to be charged, the 12V DC / DC converter 32 receives the DC power transformed from high voltage to low voltage and output by the high-voltage DC / DC converter 21, and boosts the voltage to be higher than the terminal voltage of the backup 12V LI battery 33. The 12V DC / DC converter 32 is connected to the backup 12V LI battery 33 and charges the backup 12V LI battery 33 with the boosted DC power.

[0019] The backup 12V LI battery 33 stores electric power and is, for example, a lithium-ion battery. The backup 12V LI battery 33 is connected to the 12V DC / DC converter 32 and stores the DC power boosted by the 12V DC / DC converter 32. The backup 12V LI battery 33 is connected to the load units LD2 and LD3 via a switch unit 34 (switch circuit SW2) and supplies the stored DC power to the load units LD2 and LD3. Also, the backup 12V LI battery 33 is connected to the load unit LD3 via a 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 via the switch circuit SW2 and the switch circuit SW3.

[0020] The switch unit 34 conducts or cuts off current. The switch unit 34 is composed of including 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.

[0021] 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. The switch circuit SW1 is located, for example, between the high-voltage DC / DC converter 21 and the 12V DC / DC converter 32, and switches the connection between the high-voltage DC / DC converter 21 and the 12V DC / DC converter 32. When the switch circuit SW1 is turned on, it energizes the current path connecting the high-voltage DC / DC converter 21 and the 12V DC / DC converter 32, and when it is turned off, it cuts off the current path connecting the high-voltage DC / DC converter 21 and the 12V DC / DC converter 32. Also, the switch circuit SW1 is located between the high-voltage DC / DC converter 21 and the load units LD2, LD3, and switches the connection between the high-voltage DC / DC converter 21 and the load units LD2, LD3. When the switch circuit SW1 is turned on, it energizes the current path connecting the high-voltage DC / DC converter 21 and the load units LD2, LD3, and when it is turned off, it cuts off the current path connecting the high-voltage DC / DC converter 21 and the load units LD2, LD3. Further, the switch circuit SW1 is located between the 12V lead battery 22 and the load units LD2, LD3, and switches the connection between the 12V lead battery 22 and the load units LD2, LD3. When the switch circuit SW1 is turned on, it energizes the current path connecting the 12V lead battery 22 and the load units LD2, LD3, and when it is turned off, it cuts off the current path connecting the 12V lead battery 22 and the load units LD2, LD3.

[0022] For example, when the main power supply device 20 and the backup power supply device 30 are normal, the switch circuit SW1 turns on based on the ON signal output from the control ECU 36, and energizes the current path connecting the main power supply device 20 and the backup power supply device 30. On the other hand, when an abnormality occurs in the main power supply device 20 or the backup power supply device 30, the switch circuit SW1 turns off upon receiving the output of a circuit that detects the abnormality (not shown), and can also turn off based on the OFF signal output from the control ECU 36, cutting off the current path connecting the main power supply device 20 and the backup power supply device 30.

[0023] The switch circuit SW2 is provided between the backup 12V LI battery 33, the load unit LD2, and the load unit LD3, and switches the connection between the backup 12V LI battery 33, the load unit LD2, and the load unit LD3. When the switch circuit SW2 is turned on, it energizes the current path connecting the backup 12V LI battery 33, the load unit LD2, and the load unit LD3, and when it is turned off, it cuts off the current path connecting the backup 12V LI battery 33, the load unit LD2, and the load unit LD3.

[0024] For example, when the main power supply device 20 and the backup power supply device 30 are normal, the switch circuit SW2 turns off based on the OFF signal output from the control ECU36, and cuts off the current path connecting the backup 12V LI battery 33, the load unit LD2, and the load unit LD3. On the other hand, when the main power supply device 20 is abnormal, the switch circuit SW2 can turn on by receiving the output of a circuit that detects the abnormality (not shown) and can also turn on based on the ON signal output from the control ECU36, and energizes the current path connecting the backup 12V LI battery 33, the load unit LD2, and the load unit LD3.

[0025] The switch circuit SW3 is provided between the backup 12V LI battery 33 and the load unit LD3, and switches the connection between the backup 12V LI battery 33 and the load unit LD3. When the switch circuit SW3 is turned on, it energizes the current path connecting the backup 12V LI battery 33 and the load unit LD3, and when it is turned off, it cuts off the current path connecting the backup 12V LI battery 33 and the load unit LD3.

[0026] For example, when estimating the battery state of the backup 12V LI battery 33, the switch circuit SW3 turns on based on the ON signal output from the control ECU36, and energizes the current path connecting the backup 12V LI battery 33 and the load unit LD3. On the other hand, when not estimating the battery state of the backup 12V LI battery 33, the switch circuit SW3 turns off based on the OFF signal output from the control ECU36, and cuts off the current path connecting the backup 12V LI battery 33 and the load unit LD3.

[0027] 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 resistive load portion LD3a of the load portion 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 resistive load portion LD3a of the load portion LD3. The voltage sensor 35b outputs the detected voltage value to the control ECU 36.

[0028] The control ECU 36 controls the 12VDC / DC converter 32 and the switch unit 34. The control ECU 36 includes an electronic circuit mainly composed of a well-known microcomputer including a CPU, a storage unit, and an interface. Based on the control program stored in the storage unit, the control ECU 36 monitors, for example, the state of charge of the backup 12VLI battery 33, and controls the 12VDC / DC converter 32 according to the state of charge of the backup 12VLI battery 33. For example, when the state of charge of the backup 12VLI 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 12VLI battery 33. On the other hand, when the state of charge of the backup 12VLI battery 33 is equal to or higher than the reference value, the control ECU 36 stops the output voltage of the 12VDC / DC converter 32 to maintain the state of charge of the backup 12VLI battery 33.

[0029] In addition, when the main power supply device 20 and the backup power supply device 30 are normal, the control ECU 36 makes the vehicle run in the normal mode. Here, the normal mode is a normal operating state. For example, both the 12V lead battery 22 and the backup 12V LI battery 33 are in a normal state, and it is a mode in which at least the load units LD1 and LD2 are operated. In this example, the load units LD1, LD2, and LD3 are being operated. When in the normal mode, the control ECU 36 outputs an ON signal to the switch circuit SW1, energizes 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 resistive load unit LD3a is energized. Also, when in the normal mode, the control ECU 36 outputs an OFF signal to the switch circuit SW2 to cut off the current path connecting the backup 12V LI battery 33 and the load units LD2 and LD3, outputs an OFF signal to the switch circuit SW3 to cut off the current path connecting the backup 12V LI battery 33 and the load unit LD3, and turns off the 12V DC / DC converter 32. As a result, as shown in FIG. 2, the control ECU 36 can pass a load current I1 from the high-voltage DC / DC converter 21 or the 12V lead battery 22 to the load units LD1, LD2, and LD3. Note that when the OFF signal is output, the switch circuit SW4 cuts off the current path connecting the main power supply device 20 and the resistive load unit 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 units LD1 and LD2, and the load current I1 does not flow to the load unit LD3.

[0030] On the other hand, when an abnormality occurs in the main power supply device 20 due to a ground fault or the like, the control ECU 36 causes the vehicle to run in an abnormal mode. Here, the abnormal mode is the driving state when an abnormality occurs. For example, when the main power supply device 20 is in an abnormal state, it is a mode in which the load unit LD2 is operated and the load units LD1 and LD3 are not operated. In this way, the abnormal mode is a mode in which the functions of the vehicle are restricted more than in the normal mode. Even in this abnormal mode, the vehicle can run by itself, for example, by autonomous driving, and can run in the abnormal mode to a place where the safety of the vehicle is ensured.

[0031] In the case of the abnormal mode, the control ECU 36 outputs an OFF 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, outputs an OFF signal to the switch circuit SW3 to cut off the current path connecting the backup 12V LI battery 33 and the load unit LD3. Also, in the case of the abnormal mode, the control ECU 36 outputs an ON signal to the switch circuit SW2 to energize the current path connecting the backup 12V LI battery 33, the load unit LD2, and the load unit 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 unit LD3 is turned on, and when the OFF signal is output, the load unit LD3 is turned off. However, it is assumed that the load unit LD3 can be preferentially turned off in case of an abnormality. As a result, as shown in FIG. 3, the control ECU 36 can supply a load current I2 from the backup 12V LI battery 33 to the load unit LD2 with the main power supply device 20 disconnected from the backup power supply device 30. At this time, the control ECU 36 does not supply power from the backup 12V LI battery 33 to the load unit LD1, and for the load unit LD3, it depends on the operation of the vehicle system or the driver, and there are cases where power is supplied and cases where power is not supplied.

[0032] Here, as described above, the load unit LD1 is composed of a general load unit such as an audio device, the load unit LD2 is composed of a load unit for autonomous driving such as ADAS, and the load unit LD3 is composed of a resistive load unit LD3a such as a heater. 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, different from the load units LD1 and LD2, the load unit LD3 is a load unit having other functions in addition to specific functions. As another function, the load unit LD3 has a discharging function of discharging power when estimating the battery state of the backup 12V LI battery 33. Specifically, the load unit LD3 serves as both a resistive load unit LD3a such as a heater as a specific function and a load unit (discharging circuit) that discharges power when estimating the battery state as another function. 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 discharging function when estimating the battery state.

[0033] 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 LI battery 33 to the load unit LD3 in a state where power is not supplied from the main power supply device 20 to the load unit LD3, and the battery state of the backup 12V LI battery 33 is estimated. The control ECU 36 shifts to the battery state estimation mode for estimating the battery state of the backup 12V LI battery 33 at a predetermined timing. The control ECU 36 shifts to the battery state estimation mode, for example, at the timing when the main power supply device 20 is OFF when the vehicle is parked, or at the timing when the ACC (accessory) power supply or IG (ignition) power supply of the vehicle is turned ON and the main power supply device 20 is turned ON. When the control ECU 36 shifts to the battery state estimation mode at the timing when the main power supply device 20 is OFF, for example, when the vehicle is parked, as shown in FIG. 4, an ON signal is output to the switch circuit SW3 and OFF signals are output to the switch circuits SW1 and SW2 to energize the current path connecting the backup 12V LI battery 33 and the load unit LD3. At this time, the switch circuit SW4 is OFF. Thereby, the control ECU 36 can cause a discharge current I3 to flow from the backup 12V LI battery 33 to the load unit LD3.

[0034] Also, when the control ECU 36 shifts to the battery state estimation mode at the timing when the ACC (accessory) power supply or IG (ignition) power supply of the vehicle is turned ON and the main power supply device 20 is turned ON, as shown in FIG. 5, ON signals are output to the switch circuits SW1 and SW3 and an OFF signal is output to the switch circuit SW2 to energize the current path connecting the high-voltage DC / DC converter 21 and the 12V lead battery 22 and the load units LD1, LD2, LD3, and to energize the current path connecting the backup 12V LI battery 33 and the load unit LD3. At this time, the vehicle system turns the SW4 OFF. Thereby, the control ECU 36 can cause a discharge current I3 to flow from the backup 12V LI battery 33 to the load unit LD3 while causing a load current I1 to flow through the load units LD1 and LD2.

[0035] When estimating the degradation state of the backup 12V LI battery 33 in the battery state estimation mode, the control ECU 36 obtains the internal resistance of the backup 12V LI 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 degradation state of the backup 12V LI battery 33 based on the obtained internal resistance of the backup 12V LI battery 33. Here, the degradation state represents the degree (level) of degradation of the backup 12V LI battery 33. The degree (level) of degradation is estimated according to the internal resistance of the backup 12V LI battery 33. For example, when the internal resistance of the backup 12V LI battery 33 is equal to or greater than a predetermined reference resistance, the control ECU 36 estimates that the degree of degradation of the backup 12V LI battery 33 is in an abnormal state with a high level. On the other hand, when the internal resistance of the backup 12V LI battery 33 is less than the reference resistance, the control ECU 36 estimates that the degree of the backup 12V LI battery 33 is low and not in an abnormal state.

[0036] Next, an operation example of the vehicle power supply system 1 will be described. As shown in FIG. 6, the control ECU 36 determines whether it is in the battery state estimation mode (step S1). For example, when the control ECU 36 shifts to the battery state estimation mode at the timing when the main power supply device 20 is OFF, such as when the vehicle is parked (step S1; Yes), it supplies power from the backup 12V LI battery 33 to the resistive load unit LD3a, which is a heater having a heating function (step S2). For example, as shown in FIG. 4, the control ECU 36 outputs an ON signal to the switch circuit SW3 and OFF signals to the switch circuits SW1 and SW2, energizes the current path connecting the backup 12V LI battery 33 and the load unit LD3, supplies power from the backup 12V LI battery 33 to the resistive load unit LD3a, and discharges the backup 12V LI battery 33 due to the resistance of the load unit LD3, which is a heater. At this time, the switch circuit SW4 is OFF. In the battery state estimation mode, for example, the backup 12V LI battery 33 is discharged due to the resistance of the load unit LD3 for several seconds to several tens of seconds. Next, the control ECU 36 estimates the battery state of the backup 12V LI battery 33 (step S3). For example, the control ECU 36 obtains the internal resistance of the backup 12V LI 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 LI battery 33 based on the obtained internal resistance of the backup 12V LI battery 33. In step S1 described above, when the control ECU 36 has not shifted to the battery state estimation mode (step S1; No), it determines again whether it is in the battery state estimation mode.

[0037] 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 LI 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 LI 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 function, and as another function, it has a discharge function of discharging power when estimating the battery state of the backup 12V LI battery 33. The control ECU 36 can be switched 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 20 is normal, power is supplied from the main power supply device 20 to at least the load unit LD1 and the load unit LD2. The abnormal mode is a mode in which when the main power supply device 20 is abnormal, power is supplied from the backup 12V LI battery 33 to at least the load unit LD2 and power is not supplied from the backup 12V LI battery 33 to the load unit LD1. The battery state estimation mode is a mode in which power is supplied from the backup 12V LI battery 33 to the load unit LD3 in a state where power is not supplied from the main power supply device 20 to the load unit LD3, and the battery state of the backup 12V LI battery 33 is estimated.

[0038] With this configuration, since the vehicle power supply system 1 also serves as the load part used when the load part LD3 estimates the battery state of the backup 12V LI battery 33, a dedicated load part (discharge circuit) for estimating the battery state can be reduced. As a result, the vehicle power supply system 1 can suppress an increase in the number of components and suppress enlargement, thereby reducing costs. Also, since 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, it is possible to suppress widening the interval between components in consideration of heat dissipation, and the mounting area can be reduced to an area larger than the area occupied by each component unit.

[0039] In the above vehicle power supply system 1, the backup power supply device 30 includes a switch circuit SW1 that switches the connection with the main power supply device 20, a switch circuit SW2 that switches the connection between the backup 12V LI battery 33 and the load part LD2, and a switch circuit SW3 that switches the connection between the backup 12V LI battery 33 and the load part LD3. The load part LD3 includes a switch circuit SW4 that switches the connection with the main power supply device 20. When the main power supply device 20 is normal, the control ECU 36 switches to the normal mode by turning on the switch circuit SW1 and turning off the switch circuit SW2 and the switch circuit SW3. 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 switches to the abnormal mode by turning on the switch circuit SW2 and turning off the switch circuit SW1 and the switch circuit SW3. When the control ECU 36 estimates the battery state of the backup 12V LI battery 33, it switches to the battery state estimation mode by turning on the switch circuit SW3 and turning off the switch circuit SW2 in a state where the fourth switch circuit SW4 is off. In this way, the vehicle power supply system 1 can appropriately switch between the normal mode, the abnormal mode, and the battery state estimation mode by switching each switch circuit.

[0040] In the vehicle power supply system 1 described above, 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 LI battery 33 by the resistance of the load unit LD3 which is a heater. With this configuration, the vehicle power supply system 1 can use a heater having a relatively large electrical resistance as a discharge circuit when estimating the battery state, so that the power of the backup 12V LI battery 33 can be sufficiently discharged, and the internal resistance of the backup 12V LI battery 33 can be appropriately obtained.

[0041] In the above description, the backup power supply device 30 has the switch circuit SW1, the switch circuit SW2, and the switch circuit SW3, and the load unit LD3 has the switch circuit SW4, and each mode is switched by switching each switch circuit. However, the configuration of the switch circuit for switching to each mode is not limited to the above, and other switch circuit configurations may be used. For example, the switch circuit SW4 is a switch that can be operated by a user such as a vehicle system or a driver. However, when estimating the battery state, the switch control is performed so that it automatically turns off, and after the battery state estimation is completed, the switch setting may be returned to the state immediately before. The switch circuit SW4 may be either within or outside the control range of the control ECU 36 of the backup power supply device 30.

[0042] Also, although the case where the load unit LD3 is a heater has been described, it is not limited to this, and other load units may be used.

[0043] Also, the housing 31 has been separated from the inside space portion without accommodating the power distribution portion and the fuse F, but it is not limited to this. For example, in the vehicle power supply system 1A shown in FIG. 7, the housing 31A accommodates the power distribution portion and the fuse F in its internal space portion, and the power distribution portion and the fuse F are integrated as a unit. With this configuration, the vehicle power supply system 1A can reduce the size of components such as connectors and bolt fastening parts, and can suppress an increase in the number of these components. Also, the vehicle power supply system 1A can shorten the connection path length of cables and the like for connecting between components.

[0044] Further, the load units LD1 and LD2 may each include devices that together constitute one actuator. For example, the load unit LD1 includes a first steering device, and the load unit LD2 includes a second steering device. Then, the load units LD1 and LD2 combine the first steering device and the second steering device to constitute one actuator (steering device). This actuator operates normally (normal mode) when the devices of the load unit LD1 and the devices of the load unit LD2 operate. Also, the actuator performs a restricted operation with functions restricted more than the normal operation when the devices of the load unit LD1 do not operate and the devices of the load unit LD2 operate (abnormal mode). With this configuration, the vehicle power supply system 1 can run the vehicle to a place where the safety of the vehicle can be ensured even when the main power supply device 20 is abnormal.

[0045] Also, although the battery state estimation mode has been described as estimating the degradation state of the backup 12V LI battery 33, other states than the degradation state may be estimated. For example, the battery state estimation mode may estimate the charge capacity or an abnormal state, and may also perform other state estimations related to the battery in combination with the degradation state.

Explanation of Reference Numerals

[0046] 1 Vehicle power supply system LD1 Load unit (first load unit) LD2 Load unit (second load unit) LD3 Load unit (third load unit) 20 Main power supply device 30 Backup power supply device 33 Backup 12V LI battery (backup battery) 36 Control ECU (control unit) SW1 Switch circuit (first switch circuit) SW2 Switch circuit (second switch circuit) SW3 Switch circuit (third switch circuit) SW4 Switch circuit (fourth switch circuit)

Claims

【Claim 1】 A main power supply device mounted on a vehicle that supplies power to a first load unit, a second load unit, and a third load unit, and a backup power supply device mounted on the vehicle that supplies power to at least the second load unit when the main power supply device is abnormal. 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, a control unit that controls the power supplied from the main power supply device and the backup battery, a first switch circuit that switches the connection with the main power supply device, a second switch circuit that switches the connection between the backup battery and the second load unit, and a third switch circuit that switches the connection between the backup battery and the third load unit. 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 as the other function, it has a discharge function of discharging power when estimating the battery state of the backup battery, and has a fourth switch circuit that switches the connection with the main power supply device. When the main power supply device is normal, the control unit has a normal mode in which power is supplied from the main power supply device to at least the first load unit and the second load unit, When the main power supply device is abnormal, an abnormal mode in which 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, and it can be switched to a battery state estimation mode in which power is supplied from the backup battery to the third load unit and the battery state of the backup battery is estimated while power is not being supplied from the main power supply device to the third load unit. When the main power supply device is normal, the normal mode is switched 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 abnormal mode is switched 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, in a state where the fourth switch circuit is off, the third switch circuit is turned on and the second switch circuit is turned off to switch to the battery state estimation mode. Vehicle power supply system. Claim 2 The third load unit is a heater having a heating function as the specific function. The control unit discharges the backup battery by the resistance of the third load unit, which is the heater, in the case of the battery state estimation mode. The vehicle power supply system according to claim 1. Claim 3: In the battery state estimation mode, the control unit supplies power to the third load unit to obtain the internal resistance of the backup battery, and estimates the deterioration state of the backup battery based on the internal resistance. The vehicle power supply system according to claim 1 or 2.

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