In-vehicle power supply system

Abstract

A vehicle-mounted power supply system includes: a main battery; an upper power supply unit configured to supply power to the main battery; a first power line allocated to conduct power of a first voltage; a second power line allocated to conduct power of a second voltage lower than the first voltage; a buck conversion unit configured to step down the voltage of the first power line to supply power to the second power line; and a capacitor. The input of the buck conversion unit, the upper power supply unit, and the capacitor are connected to the first power line. The output of the buck conversion unit and the main battery are connected to the second power line.

Description

Technical Field

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

[0002] In the prior art, in the auxiliary device system of an ordinary vehicle, the power supply includes an alternator (generator) that can supply power with a voltage of 12V and a vehicle-mounted battery, and this power supply supplies the power required for various electrical components to the various electrical components via a wiring harness wired in each part of the vehicle.

[0003] For example, the power supply redundancy system of Patent Document 1 includes multiple power supplies that handle two types of voltages, 12V and 48V. Since the DC / DC converter provided in the power supply can be used to convert the power supply voltage, even if a ground fault or short circuit occurs in one of the power supply systems, power can be supplied to the load.

[0004] Patent Document 1: JP-A-2019-193517 Summary of the Invention

[0005] A large number of various types of electrical components are provided in the auxiliary device system on the vehicle. Among these electrical components, large power loads that consume a very large current and small power loads that consume a small current are mixed. Examples of large power loads on the vehicle include an electric stabilizer device and an electric power steering device.

[0006] The power supply voltage required for small power loads is usually 12V, and the power supply voltage required for large power loads is usually higher than 12V. Therefore, in an ordinary vehicle with a 12V power supply, the required 48V power supply voltage, etc. is obtained by boosting the 12V power supply voltage by a DC / DC converter installed on each device with a large power load. In order to avoid an increase in power loss caused by the influence of the large current flowing through each large power load, a thick wire with a large cross-sectional area is required for the power supply wire of the wiring harness. Therefore, the power supply required for large power loads is a factor that increases the cost of the entire vehicle.

[0007] On the other hand, in the case of a vehicle having two types of power supply systems as in Patent Document 1, it is possible to supply a voltage corresponding to the power supply voltage required for each electrical component from a predetermined power supply system in a steady state. That is, it is possible to supply power from a 12V vehicle-mounted battery to electrical components that require a 12V power supply voltage, and it is possible to supply power from a 48V vehicle-mounted battery to electrical components that require a 48V power supply voltage.

[0008] However, in the system disclosed in Patent Document 1, since power supply units such as vehicle-mounted batteries for voltages of 12V and 48V respectively need to be installed for the auxiliary device system, the cost of the entire vehicle inevitably increases significantly.

[0009] However, when there are two types of power supply systems with different voltages, if only one in-vehicle battery is installed, it is expected that the power supply capacity of the power supply in the power supply system not directly connected to the in-vehicle battery will be insufficient. When a large power load is used, there is a concern that large fluctuations will occur in the power supply voltage and the operation of the in-vehicle device will become unstable.

[0010] In order to prevent large power losses from occurring when supplying power to a large power load, it is necessary to form a power supply line of a wire harness with thick wires. Since there is a possibility that relatively large voltage fluctuations will occur in the power supply voltage due to the influence of a large current flowing through the large power load, it is necessary to provide a margin for power supply voltage fluctuations for the load side circuit of the 12V system, which results in an increase in power loss.

[0011] In view of the above circumstances, the present disclosure has been made, and an object of the present disclosure is to provide an in-vehicle power supply system that can prevent an increase in the cost of the entire vehicle, reduce the diameter of the power supply line in the wire harness, and reduce power loss.

[0012] The object of the present disclosure is achieved by the following configuration.

[0013] An in-vehicle power supply system configured to supply vehicle-side power to an in-vehicle device serving as a load on a vehicle, the in-vehicle power supply system including: a main battery configured to charge and discharge power; an upper power supply unit configured to supply the power to the main battery; a first power supply line allocated to conduct power of a first voltage; a second power supply line allocated to conduct power of a second voltage lower than the first voltage; a buck conversion unit configured to step down the voltage of the first power supply line to supply power to the second power supply line; and a capacitor, wherein the input of the buck conversion unit, the upper power supply unit, and the capacitor are connected to the first power supply line, and wherein the output of the buck conversion unit and the main battery are connected to the second power supply line.

[0014] A vehicle-mounted power supply system configured to supply vehicle-side power to vehicle-mounted devices serving as loads on a vehicle, the vehicle-mounted power supply system comprising: a main battery configured to charge and discharge power; an upper power supply unit configured to supply power to the main battery; a first power line assigned to conduct power of a first voltage; a second power line assigned to conduct power of a second voltage lower than the first voltage; a buck conversion unit configured to step down the voltage of the first power line to supply power to the second power line; and a capacitor, wherein the input of the buck conversion unit, the upper power supply unit, and the main battery are connected to the first power line, and wherein the output of the buck conversion unit and the capacitor are connected to the second power line.

[0015] A vehicle-mounted power supply system configured to supply vehicle-side power to vehicle-mounted devices serving as loads on a vehicle, the vehicle-mounted power supply system comprising: a main battery configured to charge and discharge power; an upper power supply unit configured to supply power to the main battery; a first power line assigned to conduct power of a first voltage; a second power line assigned to conduct power of a second voltage lower than the first voltage; a buck conversion unit configured to step down the voltage of the first power line to supply power to the second power line; and a dark current supply circuit connected in parallel with the buck conversion unit, wherein the input of the buck conversion unit, the upper power supply unit, and the main battery are connected to the first power line, wherein the output of the buck conversion unit is connected to the second power line, and wherein the dark current supply circuit is configured to supply, as dark current, the power generated by stepping down the voltage of the first power line to the second power line when the ignition device of the vehicle is turned off.

[0016] The vehicle-mounted power supply system according to the present disclosure can prevent an increase in the cost of the entire vehicle and can also reduce the diameter of the power lines in the wiring harness and reduce power loss.

[0017] The present disclosure has been briefly described above. In addition, the details of the present disclosure will be clarified by reading the embodiments (hereinafter referred to as "Examples") of the present disclosure to be described with reference to the accompanying drawings below. Description of the Drawings

[0018] Figure 1 is a block diagram showing the main part of a vehicle-mounted power supply system according to a first embodiment of the present disclosure.

[0019] Figure 2 is a diagram showing Figure 1 the main control in the vehicle-mounted power supply system of

[0020] Figure 3 is a block diagram showing an example of connections of components installed in each part of a vehicle.

[0021] Figure 4 is a block diagram showing a main part of an in-vehicle power supply system according to a second embodiment of the present disclosure.

[0022] Figure 5 is a flowchart showing main control in an in-vehicle power supply system of Figure 4 .

[0023] Figure 6 is a block diagram showing a main part of an in-vehicle power supply system according to a third embodiment of the present disclosure. Detailed Description of the Invention

[0024] Specific embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0025] <First Embodiment>

[0026] Figure 1 is a block diagram showing a main part of an in-vehicle power supply system 10A according to a first embodiment of the present disclosure.

[0027] Figure 1 The in-vehicle power supply system 10A shown in is installed in, for example, a hybrid vehicle, an electric vehicle, or an ordinary vehicle that uses only an engine as a drive source, and can be used to supply power to various electrical components in an auxiliary device system on the vehicle.

[0028] Figure 1 The in-vehicle power supply system 10A in includes an auxiliary device system battery 13, which can supply power to various loads in an auxiliary device system that does not belong to the vehicle drive system. The auxiliary device system battery 13 is a main battery in the vehicle's auxiliary device system and is a rechargeable secondary battery having a voltage specification of 12V. The positive electrode side of the auxiliary device system battery 13 is connected to a second power line 52 of a system that processes power having a voltage of 12V. The negative electrode side of the auxiliary device system battery 13 is connected to the ground (earth) 19 of the vehicle.

[0029] On the other hand, the upstream side of the first power line 51 of the system that processes the power of the power supply with a voltage of 48V is connected to the output of the power supply control unit PCU. The input side of the power supply control unit PCU is connected to the drive system high-voltage power line 12a. The drive system high-voltage power line 12a can output power of a DC high voltage of about several hundred volts to supply a large amount of power to the motor that drives the vehicle. The power supply control unit PCU has a built-in DC / DC converter 12. The DC / DC converter 12 can step down the high voltage of the drive system high-voltage power line 12a to generate DC power of a power supply with a voltage of 48V.

[0030] In the case of a normal vehicle without the drive system high-voltage power line 12a, an alternator (ALT) is connected to the upstream side of the first power line 51 instead of the DC / DC converter 12.

[0031] The power of the power supply output by the power supply control unit PCU can be used to charge the auxiliary device system battery 13 and supply the power required for each load on the vehicle. However, when the ignition device of the vehicle is turned off, the power supply control unit PCU does not supply power to the first power line 51 side.

[0032] As Figure 1 shown, the output of the power supply control unit PCU, the capacitor 20, the large power load 14, and the input 15a of the area ECU 15 are connected to the first power line 51. The switch circuit SW1 is connected between the capacitor 20 and the first power line 51.

[0033] The large power load 14 is an electrical component that consumes a very large amount of power among various electrical components belonging to the auxiliary device system. For example, when the electric stabilizer device and the electric power steering device are operating, the electric stabilizer device and the electric power steering device installed on the vehicle consume a very large amount of power, and thus need to be treated as the large power load 14.

[0034] In the case of a normal vehicle, even for a large power load, power of a voltage of 12V is usually supplied via a standard power line, and a large current flows through the large power load. Therefore, it is necessary to make the power line for supplying power to the large power load very thick.

[0035] On the other hand, in Figure 1 the in-vehicle power supply system 10A shown, since the power of a voltage of 48V is supplied from the first power line 51 to the large power load 14, the current flowing through the large power load 14 can be significantly reduced. Therefore, the diameter of the power line of the first power line 51 can be reduced. There is no need to install a boost circuit in the large power load 14.

[0036] However, when the large power load 14 is used, the large power load 14 temporarily consumes a very large amount of power supply power, such that even when the ignition device of the vehicle is turned on, the power supply power supplied from the output of the area ECU 15 to the large power load 14 may be insufficient. To compensate for the shortage of power supply power, the capacitor 20 is included in the in-vehicle power supply system 10A.

[0037] That is, by previously accumulating charge in the capacitor 20 and discharging the charge accumulated in the capacitor 20 when the large power load 14 operates, it is possible to avoid the shortage of power supply power required by the large power load 14. It is also possible to prevent fluctuations in the power supply voltage on the second power supply line 52 and the like due to the operation of the large power load 14.

[0038] The capacitor 20 is characterized in that it is suitable for applications that supply a large current in a relatively short time compared to a storage battery such as the auxiliary device system battery 13. On the other hand, when the capacitor 20 is in a state where charge is always stored therein, the characteristics may deteriorate.

[0039] Therefore, in order to prevent the capacitor 20 from deteriorating, in the Figure 1 in-vehicle power supply system 10A, the main ECU 30A performs on-off control of the switch circuit SW1 according to the situation and performs charging and discharging of the charge in the capacitor 20 at an appropriate time.

[0040] The area ECU 15 is a device for managing the power supply to loads in a specific area on the vehicle and has a built-in DC / DC converter 16 and an internal power supply circuit 15c. The area managed by the area ECU 15 may represent a specific area in the space on the vehicle or may represent a specific group in a functional grouping. Therefore, a plurality of area ECUs 15 independent of each other are usually installed on the vehicle.

[0041] The DC / DC converter 16 in the area ECU 15 can output 12V DC power supply power generated by stepping down the 48V DC power supply power input from the first power supply line 51 to the second power supply line 52. The DC / DC converter 16 can also output 48V DC power supply power generated by stepping up the 12V DC power supply power input from the second power supply line 52 to the first power supply line 51.

[0042] As Figure 1 shown, the auxiliary device system battery 13 and the small power load 18 are connected to the second power supply line 52 on the downstream side of the area ECU 15. The second power supply line 52 belongs to a system that processes power supply power having a voltage of 12V.

[0043] The small power load 18 corresponds to an electrical component that consumes a relatively small amount of power among various electrical components belonging to the auxiliary device system. For example, electrical components such as various ECUs, various lighting devices, audio devices, and navigation devices can be treated as the small power load 18.

[0044] In Figure 1 the in-vehicle power supply system 10A, by supplying the second power line 52 with 12V power generated by stepping down the 48V power supply power appearing on the first power line 51 side using the DC / DC converter 16 in the regional ECU 15, the auxiliary device system battery 13 can be charged. The power supply power required by the small power load 18 can generally be supplied from the auxiliary device system battery 13.

[0045] On the other hand, the 12V power supply power supplied from the auxiliary device system battery 13 can be boosted by the regional ECU 15 and supplied to the first power line 51 so that the power can be supplied to the large power load 14 or can be used to charge the capacitor 20. When driving the large power load 14, if the current flowing from the second power line 52 side to the large power load 14 on the first power line 51 side increases, voltage fluctuations may occur in the second power line 52. Therefore, the charge accumulated in the capacitor 20 in advance is supplied to the large power load 14, and the current flowing from the second power line 52 side to the first power line 51 side decreases. Therefore, voltage fluctuations in the second power line 52 can be prevented.

[0046] Figure 2 is a flowchart showing Figure 1 the main control in the in-vehicle power supply system 10A. That is, through Figure 1 the main ECU 30A in Figure 2 executes the control in Figure 2 the switch circuit SW1 can be controlled according to the vehicle conditions, and the charging and discharging of the capacitor 20 can be performed at an appropriate time. The control in

[0047] When the ignition device (IG) of the vehicle is started, the main ECU 30A advances from S11 to S12. If the capacitor 20 is not charged, the switch circuit SW1 is closed to charge the capacitor 20 (S13).

[0048] When the capacitor 20 is charged, the 48V power supply power output from the power control unit PCU can be supplied to the capacitor 20, or the 48V power supply power boosted in the regional ECU 15 based on the output of the auxiliary device system battery 13 can be supplied to the capacitor 20 from the first power line 51 via the switch circuit SW1.

[0049] When the charging of the capacitor 20 is completed, the main ECU 30A turns off the switch circuit SW1 to cut off the circuit connection of the capacitor 20 (S14). Whether the charging of the capacitor 20 is completed can be determined by, for example, monitoring the voltage or current of the first power supply line 51 or managing the charging time.

[0050] In S15, the main ECU 30A monitors the state of a predetermined signal indicating the start of energization of the large power load 14, and proceeds to the process of S16 when the large power load 14 starts to be energized. The main ECU 30A closes the switch circuit SW1 to connect the circuit of the capacitor 20 to the first power supply line 51. Therefore, the charge accumulated in the capacitor 20 is discharged, and the power supply power is supplied to the large power load 14 via the first power supply line 51. A part of the power supply power output from the regional ECU 15 to the first power supply line 51 is also supplied to the large power load 14 at the same time.

[0051] Since the accumulated charge of the capacitor 20 becomes empty by executing S16, after the energization of the large power load 14 ends, the main ECU 30A proceeds to the next process of S17 to charge the capacitor 20. In fact, by keeping the switch circuit SW1 closed, the capacitor 20 is charged with the power supply power output from the power control unit PCU or the regional ECU 15.

[0052] When the charging of the capacitor 20 is completed, the main ECU 30A turns off the switch circuit SW1 to cut off the circuit connection of the capacitor 20 (S18).

[0053] On the other hand, as in the case of a parked vehicle, when the ignition device of the vehicle is turned from on to off, the main ECU 30A proceeds from S11 to S19 to the process of S20. The main ECU 30A closes the switch circuit SW1 to connect the capacitor 20 to the first power supply line 51.

[0054] When the ignition device is turned off, most of the various devices on the vehicle stop, but the circuits of some devices consume a small amount of power supply power as dark current. In the state where the switch circuit SW1 is closed in S20, the charge accumulated in the capacitor 20 is discharged as dark current to the first power supply line 51. The 12V power supply power obtained by stepping down the power supply power of the first power supply line 51 in the regional ECU 15 can be supplied as dark current to the second power supply line 52.

[0055] By supplying the dark current, the charge accumulated in the capacitor 20 gradually decreases, and the charge amount becomes 0 after a certain period of time from the start of the process of S20. When the accumulated charge in the capacitor 20 becomes 0, that is, when the discharge end state is reached, the main ECU 30A proceeds from S21 to S22 and turns off the switch circuit SW. That is, the circuit of the capacitor 20 is cut off from the first power supply line 51.

[0056] That is to say, by executing Figure 2 the control shown, when the large power load 14 is energized, the charge accumulated in the capacitor 20 can be effectively used, and the shortage of the power supply consumed by the large power load 14 and the voltage fluctuation in the first power supply line 51 can be prevented.

[0057] In addition, when the ignition device is turned off, such as in the case of vehicle parking, the charge accumulated in the capacitor 20 is automatically discharged, so that the deterioration of the characteristics of the capacitor 20 can be avoided.

[0058] Figure 3 is a block diagram showing an example of the connection of components installed in each part of the vehicle. That is, Figure 3 a specific configuration example of the in-vehicle power supply system 10A according to an embodiment of the present invention is shown. Figure 3 shows an outline of an example of the arrangement of main components in a state of observing the vehicle from above.

[0059] Figure 3 The vehicle body 50 shown in includes an engine room 50a, a cabin instrument panel area 50b, and a trunk room 50c. In the engine room 50a, various electrical components in the auxiliary device system are provided, such as a water pump 31, an oil pump 32, a cooling fan 33, an air conditioner (A / C) compressor 34, a brake actuator (ACT) 35, a catalyst heater 37, a defroster 38, an electric stabilizer 39, an electric power steering (EPS) actuator 40, and an air conditioner blower 41.

[0060] In the cabin, various electrical components in the auxiliary device system are provided, such as a positive temperature coefficient (PTC) heater 42, a seat heater 43, and an electric seat 44. Inside the trunk room 50c, various electrical components in the auxiliary device system are provided, such as an electric power assisted brake (EPB) actuator 45, an electric stabilizer 46, and a defogger 47.

[0061] In Figure 3 In the example of the in-vehicle power supply system 10A shown, the area ECU 15A is installed in the engine room 50a to manage the area allocated to the engine room 50a. To manage the left area and the right area of the cabin instrument panel area 50b, the area ECUs 15B and 15D are respectively installed in the left part and the right part of the cabin instrument panel area 50b. The area ECU 15C is installed in the trunk room 50c to manage the area allocated in the trunk room 50c.

[0062] The area ECUs 15A and 15B are connected to each other through the power supply main line 11C, the area ECUs 15B and 15C are connected to each other through the power supply main line 11D, and the area ECUs 15B and 15D are connected to each other through the power supply main line 11E.

[0063] The DC / DC converter 12 and the auxiliary device system battery 13 are connected to the regional ECU 15A via the power supply mains 11A and 11B. The input side of the DC / DC converter 12 is connected to the output of the high-voltage battery 21. The high-voltage battery 21 is formed of a secondary battery such as a lithium-ion battery, capable of storing electric power with a high voltage of, for example, about several hundred volts, and capable of supplying the stored electric power to a motor for vehicle running or the like.

[0064] The DC / DC converter 12 converts the power supply electric power of the DC high voltage of about several hundred volts output from the high-voltage battery 21 into 48V DC power supply electric power, and supplies the 48V DC power supply electric power to the power supply main 11A corresponding to the first power supply line 51 in Figure 1 .

[0065] The auxiliary device system battery 13 can be charged by inputting the DC power supply electric power stepped down from 48V to 12V in the regional ECU 15A from the power supply main 11B. The 12V DC power supply electric power accumulated by charging by the auxiliary device system battery 13 can be output to the power supply main 11B.

[0066] The power supply mains 11A, 11B, and 11C are electrically connected to each other inside the regional ECU 15A. The power supply mains 11C and 11D are electrically connected to each other inside the regional ECU 15B. Therefore, the 48V DC power supply electric power output from the DC / DC converter 12 or the 12V DC power supply electric power output from the auxiliary device system battery 13 is supplied to the power supply mains 11C and 11D. Each of the power supply mains 11C and 11D includes a power supply line for at least distributing 12V DC power supply electric power.

[0067] Each of the regional ECUs 15A, 15B, and 15C has a built-in DC / DC converter 16. Since there is no load consuming a large amount of power in the area managed by the regional ECU 15D, the regional ECU 15D is not equipped with a DC / DC converter 16. The power supply main 11E connecting the regional ECU 15B and the regional ECU 15D includes a power supply line for distributing 12V DC power supply electric power.

[0068] As Figure 3 shown, the power supply branch line 17A connected to the downstream side of the regional ECU 15A includes a 48V power supply line 22 and a 12V power supply line 23.

[0069] The 48V power supply line 22 can supply the 48V power supply electric power output from the DC / DC converter 12 or the 48V power supply electric power generated by the step-up conversion of the 12V power supply electric power by the DC / DC converter 16 in the regional ECU 15A.

[0070] The 12V power line 23 can supply 12V power generated by stepping down the 48V power by the DC / DC converter 16 in the regional ECU 15A. The 12V power line 23 can supply 12V power output from the auxiliary device system battery 13.

[0071] In Figure 3 In the illustrated example, the water pump 31, the oil pump 32, the cooling fan 33, the air conditioner compressor 34, the brake actuator 35, the catalyst heater 37, the de-icer 38, the electric stabilizer 39, the EPS actuator 40, and the air conditioner blower 41 are connected to the 48V power line 22.

[0072] In particular, since the electric stabilizer 39 and the EPS actuator 40 consume a very large amount of power, it is effective to connect the electric stabilizer 39 and the EPS actuator 40 to the 48V power line 22 supplied with 48V voltage for the purpose of reducing the diameter of wires such as the 48V power line 22 and the main line. Various small power loads that require 12V power supply voltage can be connected to the 12V power line 23.

[0073] On the other hand, the PTC heater 42, the seat heater 43, and the electric seat 44 installed in the passenger compartment are connected to the downstream side of the regional ECU 15B via the power supply branch line 17B. The power supply branch line 17B includes a power line that distributes 12V power obtained by stepping down the 48V power supplied to the power main line 11C by the DC / DC converter 16 in the regional ECU 15B.

[0074] The 12V power generated by stepping down using the DC / DC converter 16 in the regional ECU 15B is supplied to the 12V power line included in the power main line 11E. The 12V power obtained by distributing or branching the power of the 12V power line of the power main line 11E is supplied to the power supply branch line 17D connected to the downstream side of the regional ECU 15D.

[0075] On the other hand, the power supply branch line 17C of the regional ECU 15C installed in the trunk room 50c includes a 48V power line 24 and a 12V power line 25. The 48V power line 24 can output 48V power obtained by distributing or branching the 48V power supplied from the power main line 11D to the regional ECU 15C.

[0076] The 12V power line 25 can output 12V power obtained by stepping down the 48V power supplied from the power main line 11D using the DC / DC converter 16 in the regional ECU 15C.

[0077] The EPB actuator 45, the electric stabilizer 46, and the defroster 47 installed in the luggage compartment 50c are connected to the 48V power line 24. In particular, since the electric stabilizer 46 consumes a very large amount of power, it is effective to connect the electric stabilizer 46 to the 48V power line 24 supplied with 48V voltage for the purpose of reducing the diameter of wires such as the 48V power line 24 and the main line. Various small power loads that require a 12V power supply voltage can be connected to the 12V power line 25.

[0078] In Figure 3 the vehicle power supply system 10A of

[0079] <Second Embodiment>

[0080] Figure 4 is a block diagram showing a main part of a vehicle power supply system 10B according to a second embodiment of the present disclosure. Figure 4 The vehicle power supply system 10B shown in Figure 1 is a modification of the vehicle power supply system 10A shown in Figure 4 In

[0081] Figure 4 the vehicle power supply system 10B in

[0082] includes an auxiliary device system battery 13B, which can supply power to various loads in the auxiliary device system that do not belong to the vehicle drive system. The auxiliary device system battery 13B is the main battery corresponding to the 48V voltage in the auxiliary device system and is a rechargeable secondary battery. The auxiliary device system battery 13B is, for example, a lithium-ion battery. The positive electrode side of the auxiliary device system battery 13B is connected to the first power line 51. The negative electrode side of the auxiliary device system battery 13B is connected to the vehicle ground 19.

[0083] In the case of an ordinary vehicle without the high-voltage power supply line 12a of the drive system, the alternator is connected to the upstream side of the first power supply line 51 instead of the DC / DC converter 12.

[0084] The power supply power output by the power control unit PCU can be used to supply the power required for the in-vehicle power supply system 10B and each load connected to the downstream side of the in-vehicle power supply system 10B. However, when the ignition device of the vehicle is turned off, the power control unit PCU does not supply power to the first power supply line 51 side.

[0085] As Figure 4 shown, the output of the power control unit PCU, the auxiliary device system battery 13B, the large power load 14, and the input 15a of the area ECU 15 are connected to the first power supply line 51.

[0086] Therefore, when the ignition device of the vehicle is started, the 48V power supply power output from the power control unit PCU can be supplied to the auxiliary device system battery 13B via the first power supply line 51 to charge the auxiliary device system battery 13B.

[0087] The large power load 14 is an electrical component that consumes a very large amount of power among various electrical components belonging to the auxiliary device system.

[0088] In Figure 4 the in-vehicle power supply system 10B shown, since the power supply power with a voltage of 48V is supplied from the first power supply line 51 to the large power load 14, the current flowing through the large power load 14 can be significantly reduced. Therefore, the diameter of the power supply line of the first power supply line 51 can be reduced. There is no need to install a boost circuit in the large power load 14.

[0089] The 48V power supply power accumulated in the auxiliary device system battery 13B can be supplied to the large power load 14 via the first power supply line 51. When the ignition device is started, the 48V power supply power can also be supplied from the output of the power control unit PCU to the large power load 14.

[0090] The in-vehicle power supply system 10B can supply the 48V power supply power accumulated in the auxiliary device system battery 13B and the 48V power supply power output from the power control unit PCU to the area ECU 15 and the downstream side of the area ECU 15.

[0091] The area ECU 15 has a built-in DC / DC converter 16 and an internal power supply circuit 15c. The area ECU 15 has an input 15a connected to the first power supply line 51 and an output 15b connected to the second power supply line 52.

[0092] The DC / DC converter 16 in the regional ECU 15 can generate DC power with a stepped-down voltage of 12V based on the DC power supplied from the 48V voltage side of the first power line 51. The 12V DC power generated by the DC / DC converter 16 is supplied from the output 15b of the regional ECU 15 to the second power line 52.

[0093] As Figure 4 shown, the output 15b of the regional ECU 15, the capacitor 20A, and the small power load 18 are connected to the second power line 52.

[0094] One end (high potential side) of the capacitor 20A is connected to the second power line 52 via the switch circuit SW2, and the other end (low potential side) of the capacitor 20A is connected to the ground 19. The switch circuit SW3 is connected in parallel with the capacitor 20A. The switch circuit SW3 includes a switch and a resistor connected in series.

[0095] The switch circuits SW2 and SW3 can be independently opened and closed by a control signal output from the main ECU 30B. The switch circuit SW2 is controlled to close when performing a charging operation for accumulating charge in the capacitor 20A and when supplying the charge accumulated in the capacitor 20A to the load side, and to open in other cases. When the charge accumulated in the capacitor 20A is not required, the switch circuit SW3 is controlled to close so as to discharge the charge.

[0096] The small power load 18 corresponds to an electrical component that consumes a relatively small amount of power among various electrical components belonging to the auxiliary device system. For example, electrical components such as various ECUs, various lighting devices, audio devices, and navigation devices can be treated as the small power load 18.

[0097] When the ignition device of the vehicle is started, the power supplied from the auxiliary device system battery 13B can be supplied to the regional ECU 15 via the first power line 51. The 12V power generated by stepping down the voltage by the DC / DC converter 16 in the regional ECU 15 is supplied to the second power line 52, so that the required power can be supplied to the small power load 18 connected to the second power line 52.

[0098] On the other hand, when the ignition device is turned off, the small power load 18 and the like hardly operate, but some circuits consume a small amount of power as dark current as needed.

[0099] When the DC / DC converter 16 in the area ECU 15 always operates to enable the supply of the dark current, a relatively large power loss always occurs in the DC / DC converter 16. When the ignition device is turned off, power is not supplied from the power supply control unit PCU side, increasing the consumption of the power accumulated in the auxiliary device system battery 13B and potentially causing battery depletion.

[0100] However, in this embodiment, when the ignition device is turned off, the charge accumulated in the capacitor 20A can be used. Therefore, it is not necessary to always operate the DC / DC converter 16, and an increase in power loss can be prevented. When the ignition device is turned off, the charge accumulated in the capacitor 20A is intermittently charged using the power of the auxiliary device system battery 13B. Therefore, when needed, the power supply (dark current) can be supplied from the capacitor 20A to the small power load 18 or the like. That is, the operation of the DC / DC converter 16 can be limited to a temporary operation when the ignition device is turned off, and an increase in power loss can be prevented.

[0101] Compared with a storage battery such as the auxiliary device system battery 13B, the capacitor 20A has the characteristic suitable for supplying a large current in a relatively short time. On the other hand, when the capacitor 20A is kept in a state where charge is always stored therein, the deterioration of the characteristic may develop in a short time.

[0102] Therefore, in order to prevent the deterioration of the capacitor 20A, in Figure 4 the vehicle-mounted power supply system 10B, the main ECU 30B performs the opening and closing control of the switch circuits SW2 and SW3 according to the situation, and performs the charging and discharging of the charge in the capacitor 20A at an appropriate time. For example, when the ignition device is started, the switch circuit SW3 is closed to release the charge accumulated in the capacitor 20A.

[0103] Figure 5 is a flowchart showing the main control in Figure 4 the vehicle-mounted power supply system 10B. That is, Figure 4 the main ECU 30B in Figure 5 keeps the capacitor 20A in an appropriate state by performing the control in Figure 5 . The control in

[0104] The main ECU 30B identifies in S31 whether the ignition device (IG) of the vehicle is started or turned off, and proceeds from S31 to S32 when the ignition device is turned off, and proceeds from S31 to S34 when the ignition device is started.

[0105] In this embodiment, when the ignition device is turned off, the charging process of the capacitor 20A is performed at a predetermined constant time interval "as intermittent charging". That is, whenever the timing of intermittent charging arrives, the main ECU 30B proceeds with the processing from S32 to S33. Then, the switch circuit SW2 is closed so that current flows from the second power supply line 52 to the capacitor 20A to charge the capacitor 20A (S33). At this time, the switch circuit SW3 remains open.

[0106] When the capacitor 20A is being charged, the DC / DC converter 16 temporarily operates to step down the 48V power supply power supplied from the auxiliary device system battery 13B to 12V in the DC / DC converter 16, and supplies the stepped-down power supply power to the second power supply line 52.

[0107] In the case where a load that requires a dark current is connected to the second power supply line 52, when the ignition device is turned off, the switch circuit SW2 is closed as needed, the charge accumulated in the capacitor 20A discharges toward the second power supply line 52, and the dark current is supplied to the load.

[0108] On the other hand, when the ignition device is started, the main ECU 30B opens the switch circuit SW2 and closes the switch circuit SW3 (S34). Therefore, the charge accumulated in the capacitor 20A gradually discharges due to the resistor in the switch circuit SW3. As time passes, the accumulated charge amount of the capacitor 20A becomes 0. Therefore, deterioration of the characteristics of the capacitor 20A can be prevented.

[0109] <Third Embodiment>

[0110] Figure 6 is a block diagram showing a main part of the in-vehicle power supply system 10C according to the third embodiment of the present disclosure. Figure 6 The in-vehicle power supply system 10C shown in Figure 4 is a modification of the in-vehicle power supply system 10B shown in Figure 6 In

[0111] Figure 6 The in-vehicle power supply system 10C in

[0112] The upstream side of the first power supply line 51 that processes 48V voltage is connected to the output of the power control unit PCU. The input side of the power control unit PCU is connected to the high-voltage power supply line 12a of the drive system. The high-voltage power supply line 12a of the drive system can output power electricity with a DC high voltage of approximately several hundred volts to supply a large amount of power to the motor that drives the vehicle. The power control unit PCU has a built-in DC / DC converter 12. The DC / DC converter 12 can step down the high voltage of the high-voltage power supply line 12a of the drive system to generate DC power electricity with a 48V voltage.

[0113] In the case of an ordinary vehicle without the high-voltage power supply line 12a of the drive system, an alternator is connected to the upstream side of the first power supply line 51 instead of the DC / DC converter 12.

[0114] The power electricity output by the power control unit PCU can be used to supply the power electricity required by the in-vehicle power supply system 10C and each load connected to the downstream side of the in-vehicle power supply system 10C. However, when the ignition device of the vehicle is turned off, the power control unit PCU does not supply power electricity to the first power supply line 51 side.

[0115] As Figure 6 shown, the output of the power control unit PCU, the auxiliary device system battery 13B, the large power load 14, and the input 15a of the area ECU 15 are connected to the first power supply line 51.

[0116] Therefore, when the ignition device of the vehicle is started, the 48V power electricity output from the power control unit PCU can be supplied to the auxiliary device system battery 13B via the first power supply line 51 to charge the auxiliary device system battery 13B.

[0117] The large power load 14 is an electrical component that consumes a very large amount of power among various electrical components belonging to the auxiliary device system.

[0118] In Figure 4 the in-vehicle power supply system 10B shown, since power electricity with a voltage of 48V is supplied from the first power supply line 51 to the large power load 14, the current flowing through the large power load 14 can be significantly reduced. Therefore, the diameter of the power supply line of the first power supply line 51 can be reduced. There is no need to install a boost circuit in the large power load 14.

[0119] The 48V power electricity accumulated in the auxiliary device system battery 13B can be supplied to the large power load 14 via the first power supply line 51. When the ignition device is started, the 48V power electricity can be supplied from the output of the power control unit PCU to the large power load 14.

[0120] The in-vehicle power supply system 10C can supply the 48V power electric power accumulated in the auxiliary device system battery 13B and the 48V power electric power output from the power control unit PCU to the area ECU 15 and the downstream side of the area ECU 15.

[0121] The area ECU 15 has an input 15a connected to the first power supply line 51 and an output 15b connected to the second power supply line 52. The area ECU 15 has a built-in DC / DC converter 16 and an internal power supply circuit 15c. The internal power supply circuit 15c of the in-vehicle power supply system 10C includes a dark current regulator 15d.

[0122] The input side of the dark current regulator 15d is connected to the first power supply line 51, and the output side of the dark current regulator 15d is connected to the second power supply line 52. The main ECU 30C controls the dark current regulator 15d.

[0123] The DC / DC converter 16 in the area ECU 15 can generate DC power electric power with a voltage stepped down to 12V based on the DC power electric power with a voltage of 48V supplied from the first power supply line 51 side. The 12V DC power electric power generated by the DC / DC converter 16 is supplied from the output 15b of the area ECU 15 to the second power supply line 52.

[0124] In Figure 6 the in-vehicle power supply system 10C, the dark current regulator 15d in the area ECU 15 can generate DC power electric power with a voltage stepped down to 12V based on the DC power electric power with a voltage of 48V supplied from the first power supply line 51 side. In this case, the 12V DC power electric power generated by the dark current regulator 15d is supplied from the output 15b of the area ECU 15 to the second power supply line 52.

[0125] Compared with other power supply circuits, the capacity of the power electric power that can be generated by the dark current regulator 15d is very small. Therefore, the 12V power electric power can be supplied only to loads that require very little power electric power such as dark current. On the contrary, compared with other circuits, the power loss that occurs when using the dark current regulator 15d is also very small.

[0126] Specifically, when using the DC / DC converter 16 to step down the 48V voltage on the first power supply line 51 side to 12V and supply it to the second power supply line 52 side, relatively large power loss is expected to occur inside the DC / DC converter 16. However, when the operation of the DC / DC converter 16 stops and the dark current regulator 15d is used, the 12V power electric power generated by stepping down the 48V power electric power on the first power supply line 51 side with low loss is supplied to the second power supply line 52.

[0127] When the ignition device is turned off, the small power load 18 connected to the second power supply line 52 side is in a standby state and in a state of consuming only a small dark current, so that the power supply power supplied only by the dark current regulator 15d is sufficient.

[0128] When the ignition device is started, the main ECU 30C controls the DC / DC converter 16 to be in an always operable state and stops the operation of the dark current regulator 15d. When the ignition device is turned off, the operation of the DC / DC converter 16 stops, and the dark current regulator 15d switches to an operable state.

[0129] That is to say, in the vehicle-mounted power supply system 10C, when the ignition device is started, the DC / DC converter 16 in the area ECU 15 operates to generate the required 12V power supply power for the small power load 18 connected to the second power supply line 52, etc. based on the 48V power supply power on the first power supply line 51 side. In the vehicle-mounted power supply system 10C, when the ignition device is turned off, the DC / DC converter 16 is not used, but instead the dark current regulator 15d is used to generate the required 12V power supply power for the small power load 18 connected to the second power supply line 52, etc. based on the 48V power supply power on the first power supply line 51 side.

[0130] As described above, in the present embodiment, since the dark current regulator 15d is used when the ignition device is turned off, the DC / DC converter 16 can be stopped. Therefore, an increase in power loss can be prevented and battery depletion of the auxiliary device system battery 13B can be prevented.

[0131] As described above, in Figure 1 In the vehicle-mounted power supply system 10A shown, since 48V power supply power is supplied from the first power supply line 51 to the large power load 14, when the large power load 14 is driven, the current flowing through the first power supply line 51 can be reduced. Therefore, it is easy to reduce the diameter of the wire at the position of the first power supply line 51, etc. and reduce the size of the terminal.

[0132] In addition, since the charge accumulated in the capacitor 20 can be supplied to the large power load 14 via the first power supply line 51, the temporary power shortage when the power supplied to the large power load 14 is turned on can be eliminated, and the fluctuation of the power supply voltage generated in the second power supply line 52 can be prevented. Therefore, since the voltage of the second power supply line 52 is stable, the margin of the power supply voltage specification supplied to the small power load 18 can be reduced, and the power loss generated in the power supply circuit of the small power load 18 can be reduced. By connecting the auxiliary device system battery 13 to the second power supply line 52 side, an increase in cost can be prevented.

[0133] Since the main ECU 30A executes Figure 2The control shown in can thus automatically discharge the charge accumulated in the capacitor 20 when the ignition device is turned off. Therefore, deterioration of the characteristics of the capacitor 20 can be prevented.

[0134] In Figure 4 the in-vehicle power supply system 10B shown in , by connecting only the auxiliary device system battery 13B to the first power line 51 side, an increase in cost can be prevented. By connecting the capacitor 20A to the second power line 52, it is possible to supply the dark current of the power supply required for the small power load 18 from the capacitor 20A when the ignition device is turned off, without always operating the DC / DC converter 16. Therefore, the power loss that occurs in the DC / DC converter 16 when the ignition device is turned off can be reduced.

[0135] Since the main ECU 30B executes Figure 5 the control in , the capacitor 20A can be intermittently charged when the ignition device is turned off and the charged charge can be used. In addition, since the charge accumulated in the capacitor 20A automatically discharges when the ignition device is started, deterioration of the characteristics of the capacitor 20A can be prevented.

[0136] Similarly, in Figure 6 the in-vehicle power supply system 10C shown in , by connecting only the auxiliary device system battery 13B to the first power line 51 side, an increase in cost can be prevented. By using the dark current regulator 15d in the area ECU 15, it is possible to supply the dark current of the power supply required for the small power load 18 when the ignition device is turned off while the DC / DC converter 16 is stopped. By using the dedicated dark current regulator 15d, the power loss that occurs when the ignition device is turned off can be significantly reduced compared to the case of using the DC / DC converter 16.

[0137] The present disclosure is not limited to the above-described embodiments, and modifications, improvements, etc. can be appropriately made. In addition, the materials, shapes, sizes, quantities, arrangement positions, etc. of the components in the above-described embodiments are optional and not limited as long as the present invention can be implemented.

[0138] Here, the in-vehicle power supply system according to the above embodiments of the present invention will be briefly outlined below.

[0139] The in-vehicle power supply system (10A) is configured to supply vehicle-side power electric power to in-vehicle devices that serve as loads on the vehicle. The in-vehicle power supply system includes: a main battery (auxiliary device system battery 13), which is configured to charge and discharge power electric power; an upper power supply unit (power control unit PCU), which is configured to supply power electric power to the main battery; a first power line (51), which is allocated to conduct power electric power of a first voltage (e.g., 48V); a second power line (52), which is allocated to conduct power electric power of a second voltage lower than the first voltage (e.g., 12V); a step-down conversion unit (DC / DC converter 16), which is configured to step down the voltage of the first power line to supply power electric power to the second power line; and a capacitor (20). The input of the step-down conversion unit, the upper power supply unit, and the capacitor are connected to the first power line, and the output of the step-down conversion unit and the main battery are connected to the second power line.

[0140] According to the in-vehicle power supply system having the above configuration, when a large-power load is connected to the first power line, it is possible to supply sufficient power to the large-power load using the charge in the capacitor. Therefore, voltage fluctuations of the second power line can be prevented.

[0141] The in-vehicle power supply system (10A) further includes: a switch unit (switch circuit SW1), which is configured to control the circuit connection between the capacitor and the first power line; and a control unit (main ECU 30A), which is configured to control the switch unit. The control unit is configured to: control the switch unit to perform discharge of the capacitor (S20) in association with the ignition device of the vehicle being switched to off; and control the switch unit to discharge the charge accumulated in the capacitor (S15, S16) when the ignition device is in the start state and at least power electric power needs to be supplied to the large-power load.

[0142] According to the in-vehicle power supply system having the above configuration, it is possible to prevent charge from accumulating in the capacitor for a long time, thereby preventing deterioration of the capacitor. When needed, it is possible to supply power to the large-power load using the capacitor.

[0143] The in-vehicle power supply system (10B) is configured to supply vehicle-side power electric power to in-vehicle devices that serve as loads on the vehicle. The in-vehicle power supply system includes: a main battery (auxiliary device system battery 13B) configured to charge and discharge power electric power; an upper power supply unit (power control unit PCU) configured to supply power electric power to the main battery; a first power line (51) allocated to conduct power electric power of a first voltage (e.g., 48V); a second power line (52) allocated to conduct power electric power of a second voltage lower than the first voltage (e.g., 12V); a buck conversion unit (DC / DC converter 16) configured to step down the voltage of the first power line to supply power electric power to the second power line; and a capacitor (20A). The input of the buck conversion unit, the upper power supply unit, and the main battery are connected to the first power line, and the output of the buck conversion unit and the capacitor are connected to the second power line.

[0144] According to the in-vehicle power supply system having the above configuration, it is possible to supply, from the capacitor, the power electric power required for the dark current when the ignition device is turned off, so that it is not always necessary to operate the buck conversion unit, and the occurrence of power loss can be prevented. Therefore, the occurrence of battery depletion can be prevented.

[0145] The in-vehicle power supply system (10B) further includes: a switch unit (switch circuits SW2, SW3) configured to control the circuit connection between the capacitor and the second power line; and a control unit (main ECU 30B) configured to control the switch unit. The control unit is configured to: control the switch unit to charge the capacitor (S33) when the ignition device of the vehicle is turned off and a predetermined condition is satisfied; and control the switch unit to discharge the capacitor (S34) when the ignition device is started.

[0146] According to the in-vehicle power supply system having the above configuration, it is possible to accumulate the required charge in the capacitor without always operating the buck conversion unit. Since unnecessary charge is automatically discharged, the deterioration of the capacitor can be prevented.

[0147] The in-vehicle power supply system (10C) is configured to supply vehicle-side power electric power to in-vehicle devices that serve as loads on the vehicle. The in-vehicle power supply system includes: a main battery (auxiliary device system battery 13B) configured to charge and discharge power electric power; an upper power supply unit (power control unit PCU) configured to supply power electric power to the main battery; a first power line (51) assigned to conduct power electric power of a first voltage (e.g., 48V); a second power line (52) assigned to conduct power electric power of a second voltage (e.g., 12V) lower than the first voltage; a buck conversion unit (DC / DC converter 16) configured to step down the voltage of the first power line to supply power electric power to the second power line; and a dark current supply circuit (dark current regulator 15d) connected in parallel with the buck conversion unit. The input of the buck conversion unit, the upper power supply unit, and the main battery are connected to the first power line, and the output of the buck conversion unit is connected to the second power line. The dark current supply circuit is configured to supply, as dark current, the power electric power generated by stepping down the voltage of the first power line to the second power line when the ignition device of the vehicle is turned off.

[0148] According to the in-vehicle power supply system having the above configuration, it is possible to supply, from the dark current supply circuit, the power electric power required for the dark current when the ignition device is turned off, so that it is not always necessary to operate the buck conversion unit, and the occurrence of power loss can be prevented. Therefore, the occurrence of battery depletion can be prevented.

Claims

1. A vehicle power supply system configured to supply vehicle - side power to in - vehicle devices serving as loads on a vehicle, the vehicle power supply system comprising: A main battery configured to charge and discharge power; An upper - level power supply unit configured to supply power to the main battery; A first power line allocated to conduct power of a first voltage; A second power line allocated to conduct power of a second voltage, the second voltage being lower than the first voltage; A step - down conversion unit configured to step down the voltage of the first power line to supply power to the second power line; A capacitor; A switch unit configured to control the circuit connection between the capacitor and the first power line and the circuit connection between the capacitor and a high - power load; And A control unit configured to control the switch unit; Wherein, the input of the step - down conversion unit, the upper - level power supply unit, and the capacitor are connected to the first power line, and Wherein, the output of the step - down conversion unit and the main battery are connected to the second power line, Wherein, the control unit is configured to: Control the switch unit to close to discharge the capacitor in association with the vehicle ignition device being switched off; and When the ignition device is in the start state and it is necessary to supply power to at least a high - power load, control the switch unit to close to discharge the charge accumulated in the capacitor.

2. A vehicle power supply system configured to supply vehicle - side power to in - vehicle devices serving as loads on a vehicle, the vehicle power supply system comprising: A main battery configured to charge and discharge power; An upper - level power supply unit configured to supply power to the main battery; A first power line allocated to conduct power of a first voltage; A second power line allocated to conduct power of a second voltage, the second voltage being lower than the first voltage; A step - down conversion unit configured to step down the voltage of the first power line to supply power to the second power line; A capacitor; A switch unit configured to control the circuit connection between the capacitor and the second power line; And A control unit configured to control the switch unit, Wherein, the input of the step - down conversion unit, the upper - level power supply unit, and the main battery are connected to the first power line, and Wherein, the output of the step - down conversion unit and the capacitor are connected to the second power line, Wherein, the control unit is configured to: Control the switch unit to intermittently charge the capacitor when the vehicle ignition device is off and a predetermined condition is met; and When the ignition device is started, control the switch unit to discharge the capacitor.

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