On-board power supply system

Abstract

The auxiliary system battery and small power loads are connected to the first power line, and power boosted by the DC / DC converter in the zone ECU is supplied to the second power line. Large power loads and capacitors are connected to the second power line. When driving large power loads, the capacitors are connected to supply the necessary power and prevent voltage fluctuations. When the ignition is off, the switching circuit closes, supplying dark current from the capacitors and releasing the charge to prevent degradation. Alternatively, the auxiliary system battery can be connected to the second power line, and when the ignition is off, dark current is supplied to the first power line using a capacitor or a dedicated circuit.

Description

Technical Field

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

[0002] In the prior art, in the auxiliary device system of an ordinary vehicle, a power supply supplies the power required by various electrical components to various electrical components via a wiring harness wired in each part of the vehicle, and the power supply includes an AC generator (generator) capable of supplying power with a voltage of 12V and a vehicle battery.

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

[0004] Reference List

[0005] Patent Literature

[0006] Patent Document 1: JP-A-2019-193517 Summary of the Invention

[0007] Vehicle auxiliary systems are equipped with a large number of various electrical components. These components include a mixture of high-power loads that consume very high currents and low-power loads that consume low currents. Examples of high-power loads on vehicles include electric stabilizers and electric power steering systems.

[0008] The power supply voltage required for small power loads is typically 12V, while that required for large power loads is often higher. Therefore, in standard vehicles with a 12V power supply, a DC / DC converter installed in each device with large power loads steps up the 12V supply voltage to obtain the required 48V supply voltage. To avoid increased power loss due to the high current flowing through each large power load, thick wires with a large cross-sectional area are used for the power supply wiring in the wiring harness. Consequently, the power supply required for large power loads contributes to the overall cost of the vehicle.

[0009] On the other hand, in the case of a vehicle having two types of power supply systems, as in Patent Document 1, a voltage corresponding to the power supply voltage required by each electrical component can be supplied from the predetermined power supply system in a stable state. In other words, power can be supplied from the 12V vehicle battery to electrical components requiring a 12V power supply voltage, and power can be supplied from the 48V vehicle battery to electrical components requiring a 48V power supply voltage.

[0010] However, in the system disclosed in Patent Document 1, since power supply units such as on-board batteries for voltages of 12V and 48V need to be installed for the auxiliary device system, the cost of the entire vehicle is inevitably increased significantly.

[0011] However, when there are two types of power supply systems with different voltages, if only one vehicle-mounted battery is installed, the power supply capacity of the power supply system not directly connected to the vehicle-mounted battery is expected to be insufficient. When using a large power load, there is a concern that large fluctuations in the power supply voltage will occur and the operation of the vehicle-mounted device will become unstable.

[0012] To prevent significant power loss when supplying power to high-power loads, the power supply wiring harness must be constructed of thick wires. Because the high current flowing through high-power loads can potentially cause relatively large voltage fluctuations in the power supply voltage, it is necessary to provide a margin for power supply voltage fluctuations in the load-side circuits of 12V systems, which results in increased power loss.

[0013] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle-mounted power supply system that can prevent an increase in the cost of the entire vehicle, reduce the diameter of a power line in a wiring harness, and reduce power loss.

[0014] The objects of the present invention are achieved by the following configuration.

[0015] An on-vehicle power supply system that supplies power from a vehicle to an on-vehicle device serving as a load on the vehicle, the on-vehicle power supply system comprising:

[0016] a main battery configured to charge and discharge the power supply;

[0017] an upper power supply unit configured to supply power to the main battery;

[0018] a first power line assigned to be energized with power supply power at a first voltage, the first voltage being a relatively low voltage;

[0019] a second power line assigned to be energized with power at a second voltage, the second voltage being higher than the first voltage;

[0020] a voltage conversion unit configured to convert a voltage of power supply power between the first power supply line and the second power supply line; and

[0021] capacitor.

[0022] The main battery, the upper power supply unit, and the voltage conversion unit are connected to the first power supply line, and the capacitor and the voltage conversion unit are connected to the second power supply line.

[0023] An on-vehicle power supply system that supplies power from a vehicle to an on-vehicle device serving as a load on the vehicle, the on-vehicle power supply system comprising:

[0024] a main battery configured to charge and discharge the power supply;

[0025] an upper power supply unit configured to supply power to the main battery;

[0026] a first power line assigned to be energized with power supply power at a first voltage, the first voltage being a relatively low voltage;

[0027] a second power line assigned to be energized with power at a second voltage, the second voltage being higher than the first voltage;

[0028] a voltage conversion unit configured to convert a voltage of power supply power between the first power supply line and the second power supply line; and

[0029] capacitor.

[0030] The upper power supply unit, the voltage conversion unit, and the capacitor are connected to the first power supply line, and the main battery and the voltage conversion unit are connected to the second power supply line.

[0031] An on-vehicle power supply system that supplies power from a vehicle to an on-vehicle device serving as a load on the vehicle, the on-vehicle power supply system comprising:

[0032] a main battery configured to charge and discharge the power supply;

[0033] an upper power supply unit configured to supply power to the main battery;

[0034] a first power line assigned to be energized with power supply power at a first voltage, the first voltage being a relatively low voltage;

[0035] a second power line assigned to be energized with power at a second voltage, the second voltage being higher than the first voltage;

[0036] a voltage conversion unit configured to convert a voltage of power supply power between the first power supply line and the second power supply line; and

[0037] A dark current supply circuit is connected in parallel with the voltage conversion unit.

[0038] The upper power supply unit, the voltage conversion unit, and the dark current supply circuit are connected to the first power line, and the main battery, the voltage conversion unit, and the dark current supply circuit are connected to the second power line, and

[0039] The dark current supply circuit supplies power generated by stepping down a voltage of the second power line to the first power line as dark current when an ignition of the vehicle is turned off.

[0040] According to the vehicle-mounted power supply system of the present invention, it is possible to prevent an increase in the cost of the entire vehicle, and also to reduce the diameter of the power line in the wiring harness and reduce power loss.

[0041] The present invention has been briefly described above. Further, details of the present invention will be clarified by reading an embodiment for carrying out the present invention (hereinafter referred to as "embodiment"), and the present invention will be described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 1 is a block diagram showing the main parts of the vehicle-mounted power supply system according to the first embodiment of the present invention.

[0043] Figure 2 It shows Figure 1 Flowchart of the main control in the vehicle power supply system.

[0044] Figure 3 is a block diagram showing a connection example of components installed in each portion of a vehicle.

[0045] Figure 4 1 is a block diagram showing a main portion of an in-vehicle power supply system according to a second embodiment of the present invention.

[0046] Figure 5 It shows Figure 4 Flowchart of the main control in the vehicle power supply system.

[0047] Figure 6 1 is a block diagram showing a main portion of an in-vehicle power supply system according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0048] Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0049] Figure 1 1 is a block diagram showing the main parts of an in-vehicle power supply system 10A according to a first embodiment of the present invention.

[0050] Figure 1 The vehicle-mounted power supply system 10A shown in FIG is mounted on, for example, a hybrid car, an electric vehicle, or an ordinary vehicle using 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.

[0051] Figure 1 The vehicle-mounted power supply system 10A includes an auxiliary system battery 13, which is capable of supplying power to various loads in the auxiliary system that are not part of the vehicle's drive system. The auxiliary system battery 13 is a rechargeable secondary battery and serves as the main battery for the vehicle's auxiliary system. The positive electrode of the auxiliary system battery 13 is connected to the first power line 51 via a switching circuit SW. The negative electrode of the auxiliary system battery 13 is connected to the vehicle ground (earth).

[0052] The upstream side of the first power line 51 is connected to the output of the power control unit (PCU). The input side of the power control unit (PCU) is connected to the drive system high-voltage power line 12a. The drive system high-voltage power line 12a is capable of outputting power with a DC high voltage of approximately several hundred volts, enabling the supply of high power to the electric motor that drives the vehicle. The power control unit (PCU) has a built-in DC / DC converter 12. The DC / DC converter 12 is capable of stepping down the high voltage of the drive system high-voltage power line 12a to generate DC power with a voltage of 12V.

[0053] In the case of an ordinary vehicle without the drive system high-voltage power supply line 12 a , an alternating current generator (ALT) is connected to the upstream side of the first power supply line 51 instead of the DC / DC converter 12 .

[0054] The power output by the power control unit PCU can be used to charge the auxiliary device system battery 13 and supply power required by each load on the vehicle. However, when the ignition of the vehicle is turned off, the power control unit PCU does not supply power to the first power line 51 side.

[0055] like Figure 1 As shown, the output of the power control unit PCU, the auxiliary device system battery 13 , the small power loads 18 , and the input 15 a of the zone ECU 15 are connected to a first power line 51 .

[0056] The small power load 18 corresponds to an electric component that consumes a relatively small amount of power among various electric components belonging to the auxiliary device system. For example, electric components such as various ECUs, various lighting devices, audio devices, and navigation devices can be handled as the small power load 18.

[0057] The regional ECU 15 manages power supply to loads in specific areas of the vehicle and has a built-in DC / DC converter 16 and internal power supply circuit 15c. The areas managed by the regional ECU 15 can represent specific areas within the vehicle's space or specific groups within a functional grouping. Therefore, multiple independent regional ECUs 15 are typically installed in the vehicle.

[0058] The DC / DC converter 16 in the regional ECU 15 can generate DC power having a voltage stepped up to 48 V based on the 12 V DC power supplied from the first power line 51. The 48 V DC power generated by the DC / DC converter 16 is supplied from the output 15 b of the regional ECU 15 to the second power line 52.

[0059] like Figure 1 As shown, the capacitor 20 and the large power load 14 are connected to the second power supply line 52 on the output side of the zone ECU 15. A switch circuit SW1 is provided between the second power supply line 52 and the capacitor 20.

[0060] The high-power load 14 is an electrical component that consumes a significant 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 in operation, the electric stabilizer device and the electric power steering device installed on the vehicle consume a significant amount of power from the power supply and therefore need to be handled as the high-power load 14.

[0061] In the case of ordinary vehicles, even for large power loads, power supply power with a voltage of 12V is generally supplied via a standard power line, and a large current flows through the large power load. Therefore, the power line for supplying power to the large power load needs to be made very thick.

[0062] On the other hand, Figure 1 In the illustrated in-vehicle power supply system 10A, since the power supply having a voltage of 48V is supplied to the high-power load 14 from the second power supply line 52, the current flowing through the high-power load 14 can be significantly reduced. Consequently, the diameter of the power line of the second power supply line 52 can be reduced. This eliminates the need to install a boost circuit within the high-power load 14.

[0063] However, when the large-power load 14 is used, the large-power load 14 temporarily consumes a very large amount of power, so that even when the ignition of the vehicle is turned on, the power supplied to the large-power load 14 from the output of the zone ECU 15 may be insufficient. In order to compensate for the insufficient power, the capacitor 20 is provided in the vehicle power supply system 10A.

[0064] That is, by accumulating charge in the capacitor 20 in advance and discharging the charge accumulated in the capacitor 20 when the high-power load 14 is operating, it is possible to avoid a shortage of power required by the high-power load 14. It is also possible to prevent the power supply voltage on the first power supply line 51 side from fluctuating due to the energization of the high-power load 14.

[0065] The capacitor 20 has characteristics for applications of supplying a large current in a relatively short time compared to a secondary battery such as the auxiliary device system battery 13. On the other hand, when the capacitor 20 is kept in a state where electric charge is always stored therein, the characteristics may deteriorate.

[0066] Therefore, in order to prevent the capacitor 20 from deteriorating, Figure 1 In the in-vehicle power supply system 10A, the main ECU 30A performs opening and closing control of the switch circuit SW1 according to the situation, and performs charging and discharging of the electric charge in the capacitor 20 at appropriate times.

[0067] Figure 2 It shows Figure 1 Flowchart of the main control in the vehicle-mounted power supply system 10A. Figure 1 The main ECU 30A executes Figure 2 The control in the vehicle can control the switch circuit SW1 and perform charging and discharging of the capacitor 20 at an appropriate time according to the situation of the vehicle. Figure 2 in the control.

[0068] When the ignition (IG) of the vehicle is turned on, the main ECU 30A proceeds from S11 to S12 . If the capacitor 20 is not charged, the switch circuit SW1 is closed to charge the capacitor 20 .

[0069] When the capacitor 20 is charged, the DC / DC converter 16 in the area ECU 15 generates 48V power supply power based on the power supply power supplied from the auxiliary device system battery 13. The power supply power is supplied to the capacitor 20 via the switch circuit SW1.

[0070] When charging of capacitor 20 is completed, main ECU 30A opens switch circuit SW1 to disconnect capacitor 20. Whether charging of capacitor 20 is completed can be determined by, for example, monitoring the voltage or current of second power supply line 52 or managing charging time.

[0071] In S15, the main ECU 30A monitors the status of a predetermined signal indicating the start of energization of the large-power load 14 and, when energization of the large-power load 14 begins, proceeds to S16. The main ECU 30A closes the switch circuit SW1 to connect the circuit of the capacitor 20 to the second power supply line 52. As a result, the charge accumulated in the capacitor 20 is discharged, and power is supplied to the large-power load 14 via the second power supply line 52. The power output from the zone ECU 15 to the second power supply line 52 is also simultaneously supplied to the large-power load 14.

[0072] Since the accumulated charge of capacitor 20 is drained by executing S16, after the energization of large power load 14 ends, main ECU 30A proceeds to the next S17 process to charge capacitor 20. In practice, by keeping switch circuit SW1 closed, capacitor 20 is charged by the power supply output from zone ECU 15.

[0073] When 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 ).

[0074] On the other hand, when the ignition of the vehicle is turned off from on, as in the case of a parked vehicle, the main ECU 30A proceeds to S20 via S11 to S19 . The main ECU 30A closes the switch circuit SW1 to connect the capacitor 20 to the second power supply line 52 .

[0075] When the ignition is turned off, most of the various devices on the vehicle are turned off, but the circuits of some devices consume a small amount of 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 to the second power line 52 as dark current.

[0076] Therefore, the charge accumulated in capacitor 20 gradually decreases and becomes zero after a period of time from the start of the process in S20. When the accumulated charge in capacitor 20 becomes zero, that is, when the discharge is completed, main ECU 30A proceeds from S21 to S22 and turns off switch circuit SW1. In other words, the circuit of capacitor 20 is disconnected from second power supply line 52.

[0077] That is, by executing Figure 2 The control shown can effectively use the charge accumulated in the capacitor 20 when the large-power load 14 is energized, and can prevent the shortage of the power consumed by the large-power load 14 and the voltage fluctuation in the second power supply line 52.

[0078] Furthermore, when the ignition is turned off, as in a case where the vehicle is parked, the charge accumulated in the capacitor 20 is automatically discharged, so that degradation of the characteristics of the capacitor 20 can be avoided.

[0079] Figure 3 It is a block diagram showing a connection example 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 the embodiment of the present invention is shown. Figure 3 An outline of an arrangement example of main components in a state where the vehicle is viewed from above is shown.

[0080] Figure 3 The vehicle body 50 shown in FIG. 5 includes an engine compartment 50 a, a dashboard area 50 b, and a trunk compartment 50 c. Various electrical components of an auxiliary system are located in the engine compartment 50 a, such as a water pump 31, an oil pump 32, a cooling fan 33, an air conditioning (A / C) compressor 34, a brake actuator (ACT) 35, a catalyst heater 37, a de-icer 38, an electric stabilizer 39, an electric power steering (EPS) actuator 40, and an air conditioning blower 41.

[0081] In the vehicle cabin, various electrical components of the auxiliary device system are provided, such as a positive temperature coefficient (PTC) heater 42, a seat heater 43, and a power seat 44. In the trunk room 50c, various electrical components of the auxiliary device system are provided, such as an electric power assist brake (EPB) actuator 45, an electric stabilizer 46, and a defogger 47.

[0082] exist Figure 3 In the example of an in-vehicle power supply system 10A shown, a zone ECU 15A is installed in the engine compartment 50a to manage the zone assigned to the engine compartment 50a. To manage the left and right zones of the instrument panel area 50b, zone ECUs 15B and 15D are installed in the left and right portions of the instrument panel area 50b, respectively. A zone ECU 15C is installed in the trunk compartment 50c to manage the zone assigned to the trunk compartment 50c.

[0083] The area ECUs 15A and 15B are connected to each other via a power supply trunk line 11C, the area ECUs 15B and 15C are connected to each other via a power supply trunk line 11D, and the area ECUs 15B and 15D are connected to each other via a power supply trunk line 11E.

[0084] The DC / DC converter 12 and the auxiliary device system battery 13 are connected to the regional ECU 15A via 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, is capable of storing electric power having a high voltage of, for example, approximately several hundred volts, and is capable of supplying the stored electric power to the electric motor used for vehicle travel, etc.

[0085] The DC / DC converter 12 converts the power supply power having a DC high voltage of about several hundred volts output from the high voltage battery 21 into a 12V DC power supply power and supplies the 12V DC power supply power to the Figure 1 The first power line 51 in FIG. 1 corresponds to the power main line 11A. The auxiliary device system battery 13 is charged by the 12V DC power supplied from the DC / DC converter 12, and the 12V DC power accumulated by the charging can be output to the power main line 11B.

[0086] Power supply mains 11A, 11B, and 11C are electrically connected to one another within regional ECU 15A. Power supply mains 11C and 11D are electrically connected to one another within regional ECU 15B. Thus, 12V DC power output from DC / DC converter 12 or auxiliary device system battery 13 is supplied to power supply mains 11C and 11D. Each of power supply mains 11C and 11D includes at least a power line for distributing the 12V DC power.

[0087] Each of the regional ECUs 15A, 15B, and 15C has a built-in DC / DC converter 16. Since there are no loads that consume large amounts 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 trunk line 11E connecting the regional ECUs 15B and 15D includes a power supply line for distributing 12V DC power.

[0088] like Figure 3 As 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. The 48V power supply line 22 is a power supply line for outputting the power supply power (48V) output from the DC / DC converter 16 in the regional ECU 15A. The DC / DC converter 16 generates the 48V power supply power by step-up conversion of the 12V power supply power. The 12V power supply line 23 is a power supply line for outputting the power supply power (12V) obtained by dividing or branching the 12V DC power supply power supplied from the power supply main line 11A or 11B.

[0089] exist Figure 3 In the example shown, a water pump 31 , an oil pump 32 , a cooling fan 33 , an air conditioning compressor 34 , a brake actuator 35 , a catalyst heater 37 , a de-icer 38 , an electric stabilizer 39 , an EPS actuator 40 , and an air conditioning blower 41 are connected to the 48V power line 22 .

[0090] In particular, since the electric stabilizer 39 and the EPS actuator 40 consume a very large amount of electric 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 electric wires such as the 48V power line 22 and the main line. Various small electric loads that require a 12V power supply voltage can be connected to the 12V power line 23.

[0091] On the other hand, the PTC heater 42, seat heater 43, and power seat 44 installed in the vehicle cabin are connected to the downstream side of the regional ECU 15B via a power branch line 17B. The power branch line 17B includes a power line that distributes 12V power obtained by dividing or branching the 12V power supply power supplied to the power supply trunk line 11C in the regional ECU 15B.

[0092] The 12V power supply line included in the power trunk line 11E is supplied with 12V power branched in the area ECU 15B. The 12V power supply line 17D connected to the downstream side of the area ECU 15D is supplied with 12V power supply obtained by dividing or branching the power of the 12V power supply line of the power trunk line 11E.

[0093] 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 supply line 24 and a 12V power supply line 25. The 48V power supply line 24 is capable of outputting 48V power obtained by boosting the 12V power supplied from the power supply main line 11D using the DC / DC converter 16 in the regional ECU 15C. The 12V power supply line 25 is capable of outputting 12V power obtained by dividing or branching the 12V power supplied from the power supply main line 11D in the regional ECU 15C.

[0094] The EPB actuator 45, the electric stabilizer 46, and the defogger 47 installed in the trunk room 50c are connected to the 48V power line 24. In particular, since the electric stabilizer 46 consumes a significant amount of power, connecting the electric stabilizer 46 to the 48V power line 24, which is supplied with a 48V voltage, is effective for reducing the diameter of wires such as the 48V power line 24 and the main line. Various small electrical loads requiring a 12V power supply voltage can be connected to the 12V power line 25.

[0095] exist Figure 3 In the vehicle power supply system 10A, since there are relatively few high-power loads in the area to the right of the instrument panel in the vehicle cabin, which is managed by the area ECU 15D, the area ECU 15D, which includes a 12V power line and does not include a DC / DC converter 16, is installed in the power supply trunk line 11E. It is desirable that the power supply trunk line 11E also includes a 48V power line so that high-power loads can also be connected to the downstream side of the area ECU 15D.

[0096] <Second embodiment>

[0097] Figure 4 1 is a block diagram showing the main parts of an in-vehicle power supply system 10B according to a second embodiment of the present invention. Figure 4 The vehicle-mounted power supply system 10B shown in FIG. Figure 1 A variation of the vehicle-mounted power supply system 10A shown in FIG. Figure 4 Components identical to those of the in-vehicle power supply system 10A are denoted by the same reference numerals.

[0098] Figure 4 The onboard power supply system 10B includes an auxiliary system battery 13B, which is capable of supplying power to various loads in the auxiliary system that are not part of the vehicle's drive system. The auxiliary system battery 13B is a rechargeable secondary battery that operates at 48V and is the main battery in the auxiliary system. For example, the auxiliary system battery 13B is a lithium-ion battery. The positive electrode of the auxiliary system battery 13B is connected to the second power supply line 52 via a switch circuit SW0. The negative electrode of the auxiliary system battery 13B is connected to the vehicle ground 19.

[0099] On the other hand, the upstream side of the first power supply line 51, which handles 12V 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 drive system high-voltage power supply line 12a. The drive system high-voltage power supply line 12a is capable of outputting power with a DC high voltage of approximately several hundred volts, thereby supplying a large amount of power to the electric motor that drives the vehicle. The power control unit (PCU) has a built-in DC / DC converter 12. The DC / DC converter 12 is capable of stepping down the high voltage of the drive system high-voltage power supply line 12a to generate DC power with a voltage of 12V.

[0100] In the case of an ordinary vehicle without the drive system high-voltage power supply line 12 a , an alternator is connected to the upstream side of the first power supply line 51 instead of the DC / DC converter 12 .

[0101] The power output by the power control unit PCU can be used to supply the power required by the vehicle power supply system 10B and each load connected to the downstream side of the vehicle power supply system 10B. However, when the ignition of the vehicle is turned off, the power control unit PCU does not supply power to the first power line 51.

[0102] like Figure 4 As shown, the output of the power control unit PCU, the circuit of the capacitor 20A, the small power load 18 , and the input 15 a of the zone ECU 15 are connected to a first power line 51 .

[0103] One end (high potential side) of the capacitor 20A is connected to the first power supply line 51 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.

[0104] Switch circuits SW2 and SW3 can be independently opened and closed by control signals output from main ECU 30B. Switch circuit SW2 is controlled to be closed when charging capacitor 20A and supplying the charge accumulated in capacitor 20A to the load side, and is otherwise open. When the charge accumulated in capacitor 20A is no longer needed, switch circuit SW3 is controlled to be closed to discharge the charge.

[0105] 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 handled as the small power load 18.

[0106] The area ECU 15 has a built-in DC / DC converter 16 and an internal power supply circuit 15 c . The area ECU 15 has an input 15 a connected to a first power supply line 51 and an output 15 b connected to a second power supply line 52 .

[0107] The DC / DC converter 16 in the regional ECU 15 can generate DC power having a voltage stepped up to 48 V based on the 12 V DC power supplied from the first power line 51. The 48 V DC power generated by the DC / DC converter 16 is supplied from the output 15 b of the regional ECU 15 to the second power line 52.

[0108] exist Figure 4 In the in-vehicle power supply system 10B, the DC / DC converter 16 in the regional ECU 15 is also capable of performing voltage conversion in the opposite direction to that described above. Specifically, the DC / DC converter 16 is capable of generating DC power having a voltage reduced to 12V based on the 48V DC power supplied from the second power line 52. In this case, the 12V DC power generated by the DC / DC converter 16 is supplied from the input 15a of the regional ECU 15 to the first power line 51.

[0109] like Figure 4 As shown, the output 15b of the zone ECU 15, the large power load 14, and the auxiliary device system battery 13B are connected to the second power supply line 52. A switch circuit SW0 is connected between the auxiliary device system battery 13B and the second power supply line 52.

[0110] The large power load 14 is an electric component that consumes a very large amount of electric power among various electric components belonging to the auxiliary device system.

[0111] exist Figure 4 In the illustrated in-vehicle power supply system 10B, since the power supply having a voltage of 48V is supplied to the high-power load 14 from the second power supply line 52, the current flowing through the high-power load 14 can be significantly reduced. Consequently, the diameter of the power line of the second power supply line 52 can be reduced, eliminating the need to install a boost circuit within the high-power load 14.

[0112] The 48V power accumulated in the auxiliary device system battery 13B can be supplied to the large-power load 14 via the second power supply line 52. The power accumulated in the auxiliary device system battery 13B can be stepped down to 12V in the regional ECU 15 and supplied to the small-power load 18 from the first power supply line 51. Furthermore, the power accumulated in the auxiliary device system battery 13B can be stepped down to 12V in the regional ECU 15 and supplied to the capacitor 20A from the first power supply line 51 to charge the capacitor 20A.

[0113] On the other hand, when the vehicle's ignition is on, power output from the power control unit PCU can be supplied to the area ECU 15 via the first power line 51. The 48V power generated by the DC / DC converter 16 in the ECU 15, which is stepped up, can be used to charge the auxiliary device system battery 13B or to supply power to the large power load 14 to cope with power shortages.

[0114] On the other hand, when the ignition of the vehicle is off, the power control unit PCU does not output power, so that the power accumulated in the auxiliary device system battery 13B is used. When the capacitor 20A accumulates charge, the power of the capacitor 20A can also be used.

[0115] When the ignition is off, some circuits of various loads consume a small amount of power as dark current as needed, making the required power consumption very small. However, it is necessary to use the DC / DC converter 16 to supply the power of the auxiliary device system battery 13B to the first power line 51 side. When the DC / DC converter 16 is always running, it is expected that relatively large power loss will always occur inside the DC / DC converter 16.

[0116] However, in this embodiment, the charge accumulated in capacitor 20A can be used when the ignition is turned off. Therefore, it is not necessary to always operate DC / DC converter 16, and an increase in power loss can be prevented. When the ignition is turned off, the charge accumulated in capacitor 20A is intermittently charged using power from auxiliary system battery 13B. Therefore, power (dark current) can be supplied from capacitor 20A to small power loads 18, etc., when necessary. In other words, the operation of DC / DC converter 16 when the ignition is turned off can be limited to temporary operation, and an increase in power loss can be prevented.

[0117] Compared to a secondary battery such as the auxiliary device system battery 13B, the capacitor 20A has characteristics suitable for applications where a large current is supplied in a relatively short time. On the other hand, when the capacitor 20A is kept in a state where charge is always stored therein, degradation of the characteristics may develop in a short time.

[0118] Therefore, in order to prevent the capacitor 20A from deteriorating, Figure 4 In the vehicle power supply system 10B, main ECU 30B controls the opening and closing of switch circuits SW2 and SW3 according to the situation, charging and discharging the charge in capacitor 20A at the appropriate time. For example, when the ignition is turned on, switch circuit SW3 closes to release the charge accumulated in capacitor 20A.

[0119] Figure 5 It shows Figure 4 Flowchart of the main control in the vehicle power supply system 10B. That is, Figure 4 The main ECU 30B in the Figure 5 The control in the capacitor 20A is kept in the appropriate state. Figure 5 in the control.

[0120] The main ECU 30B identifies whether the ignition (IG) of the vehicle is on or off in S31 , and proceeds from S31 to S32 when the ignition is off, and proceeds from S31 to S34 when the ignition is on.

[0121] In this embodiment, when the ignition is off, capacitor 20A is charged as "intermittent charging" at predetermined, constant time intervals. That is, whenever intermittent charging is timed, main ECU 30B proceeds to steps S32 through S33. Switch circuit SW2 then closes to allow current to flow from first power line 51 to capacitor 20A, charging capacitor 20A (S33). At this time, switch circuit SW3 remains open.

[0122] When the capacitor 20A is charged, the DC / DC converter 16 temporarily operates to step down 48V power supplied from the auxiliary device system battery 13B to 12V in the DC / DC converter 16 and supply the stepped-down power to the first power line 51 .

[0123] When a load requiring dark current is connected to the first power line 51 , when the ignition is turned off, the switch circuit SW2 is closed as needed, the charge accumulated in the capacitor 20A is discharged toward the first power line 51 , and dark current is supplied to the load.

[0124] On the other hand, when the ignition is turned on, main ECU 30B opens switch circuit SW2 and closes switch circuit SW3 (S34). Consequently, the charge accumulated in capacitor 20A gradually discharges through the resistor in switch circuit SW3. Over time, the accumulated charge in capacitor 20A reaches zero. This prevents degradation of the characteristics of capacitor 20A.

[0125] <Third embodiment>

[0126] Figure 6 10C is a block diagram showing the main parts of an in-vehicle power supply system 10C according to a third embodiment of the present invention. Figure 6 The vehicle-mounted power supply system 10C shown in FIG. Figure 4 A variation of the vehicle-mounted power supply system 10B shown in FIG. Figure 6 Components identical to those of the in-vehicle power supply system 10B are denoted by the same reference numerals.

[0127] Figure 6 The vehicle-mounted power supply system 10C includes an auxiliary system battery 13B, which is capable of supplying power to various loads in the auxiliary system that are not part of the vehicle's drive system. The auxiliary system battery 13B is a rechargeable secondary battery that operates at 48V and is the main battery in the auxiliary system. For example, the auxiliary system battery 13B is a lithium-ion battery. The positive electrode of the auxiliary system battery 13B is connected to the second power supply line 52 via a switch circuit SW0. The negative electrode of the auxiliary system battery 13B is connected to the vehicle ground 19.

[0128] On the other hand, the upstream side of the first power supply line 51, which handles 12V 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 drive system high-voltage power supply line 12a. The drive system high-voltage power supply line 12a is capable of outputting power with a DC high voltage of approximately several hundred volts, thereby supplying a large amount of power to the electric motor that drives the vehicle. The power control unit (PCU) has a built-in DC / DC converter 12. The DC / DC converter 12 is capable of stepping down the high voltage of the drive system high-voltage power supply line 12a to generate DC power with a voltage of 12V.

[0129] In the case of an ordinary vehicle without the drive system high-voltage power supply line 12 a , an alternator is connected to the upstream side of the first power supply line 51 instead of the DC / DC converter 12 .

[0130] The power output by the power control unit PCU can be used to supply the power required by the vehicle power supply system 10C and each load connected to the downstream side of the vehicle power supply system 10C. However, when the ignition of the vehicle is turned off, the power control unit PCU does not supply power to the first power line 51.

[0131] like Figure 6 As shown, the output of the power control unit PCU, the small power load 18 , and the input 15 a of the zone ECU 15 are connected to a first power line 51 .

[0132] 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 handled as the small power load 18.

[0133] The regional ECU 15 has an input 15a connected to a first power line 51 and an output 15b connected to a second power line 52. The regional 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 vehicle-mounted power supply system 10C includes a dark current regulator 15d.

[0134] The input side of the dark current regulator 15d is connected to the second power supply line 52 via the switch circuit SW4, and the output side of the dark current regulator 15d is connected to the first power supply line 51 via the diode D1. The diode D1 prevents reverse current from flowing. The main ECU 30C controls the switch circuit SW4.

[0135] The DC / DC converter 16 in the regional ECU 15 can generate DC power having a voltage stepped up to 48 V based on the 12 V DC power supplied from the first power line 51. The 48 V DC power generated by the DC / DC converter 16 is supplied from the output 15 b of the regional ECU 15 to the second power line 52.

[0136] exist Figure 6 In the in-vehicle power supply system 10C, the dark current regulator 15d in the regional ECU 15 is capable of generating DC power having a voltage of 12V based on the DC power having a voltage of 48V supplied from the second power line 52. The 12V DC power generated by the dark current regulator 15d passes through a diode D1 and is supplied from the input 15a of the regional ECU 15 to the first power line 51.

[0137] Compared to other power supply circuits, the capacity of power generated by the dark current regulator 15d is very small. Therefore, 12V power can be supplied only to loads that require very little power, such as dark current. Conversely, the power loss incurred when using the dark current regulator 15d is also very small compared to other circuits.

[0138] Specifically, when the 48V voltage on the second power supply line 52 side is stepped down to 12V using the DC / DC converter 16 and supplied to the first power supply line 51 side, it is expected that relatively large power loss will occur inside the DC / DC converter 16. However, when the operation of the DC / DC converter 16 is stopped and the dark current regulator 15d is used, the 12V power supply power generated by stepping down the 48V power supply power on the second power supply line 52 side with low loss can be supplied to the first power supply line 51.

[0139] When the ignition is off, the small power load 18 connected to the first power line 51 side is in a standby state and is in a state of consuming only a small dark current, so that only the power supply power supplied by the dark current regulator 15d is sufficient.

[0140] The main ECU 30C opens the switch circuit SW4 when the ignition is on, and closes the switch circuit SW4 when the ignition is off. When the ignition is off, the operation of the DC / DC converter 16 stops.

[0141] When the switch circuit SW4 is closed, the power accumulated in the auxiliary device system battery 13B is supplied to the input of the dark current regulator 15d through the switch circuit SW0, the second power line 52, and the switch circuit SW4, so that the dark current regulator 15d generates 12V power. The 12V power generated by the dark current regulator 15d is then supplied to the small power load 18 through the diode D1 and the first power line 51.

[0142] like Figure 6 As shown, the output 15b of the zone ECU 15, the large power load 14, and the auxiliary device system battery 13B are connected to the second power supply line 52. A switch circuit SW0 is connected between the auxiliary device system battery 13B and the second power supply line 52.

[0143] exist Figure 6 In the illustrated in-vehicle power supply system 10C, since the power supply having a voltage of 48V is supplied to the high-power load 14 from the second power supply line 52, the current flowing through the high-power load 14 can be significantly reduced. Consequently, the diameter of the power line of the second power supply line 52 can be reduced, eliminating the need to install a boost circuit within the high-power load 14.

[0144] When the vehicle's ignition is on, power output from the power control unit PCU can be supplied to the zone ECU 15 via the first power line 51. The 48V power generated by stepping up the DC / DC converter 16 in the zone ECU 15 can be used to charge the auxiliary device system battery 13B or to supply power to the high-power load 14 to cope with a power shortage. The 48V power accumulated in the auxiliary device system battery 13B can be supplied to the high-power load 14 via the second power line 52.

[0145] On the other hand, when the ignition of the vehicle is turned off, the power control unit PCU does not output power, so that power of approximately the dark current required by the load on the first power line 51 side is generated based on the power accumulated in the auxiliary device system battery 13B. That is, the power accumulated in the auxiliary device system battery 13B is stepped down to 12 V by the dark current regulator 15 d in the zone ECU 15 and supplied to the small power load 18 from the first power line 51.

[0146] As described above, in this embodiment, since the dark current regulator 15d is used when the ignition is turned off, the DC / DC converter 16 can be stopped. Therefore, an increase in power loss can be prevented.

[0147] As mentioned above, in Figure 1 In the illustrated in-vehicle power supply system 10A, 48V power is generated by boosting the 12V power supplied from the first power line 51 using a DC / DC converter 16 and then supplied to the high-power load 14. This facilitates reducing the wire diameter and terminal size at locations such as the second power line 52. Connecting the auxiliary device system battery 13 to the first power line 51 prevents cost increases. Connecting the capacitor 20 to the second power line 52 also helps prevent temporary power shortages and power voltage fluctuations when the high-power load 14 is energized.

[0148] Since the main ECU 30A executes Figure 2 By the control shown in , it is possible to automatically discharge the charge accumulated in the capacitor 20 when the ignition is turned off. Therefore, it is possible to prevent the characteristics of the capacitor 20 from being deteriorated.

[0149] exist Figure 4 In the illustrated in-vehicle power supply system 10B, cost increases can be prevented by connecting the auxiliary device system battery 13 only to the second power line 52. By connecting the capacitor 20A to the first power line 51, the dark current required to power the small power loads 18 when the ignition is off can be supplied from the capacitor 20A, eliminating the need to constantly operate the DC / DC converter 16. Consequently, power loss in the DC / DC converter 16 when the ignition is off can be reduced.

[0150] Since the main ECU 30B executes Figure 5 Because the control in the ignition is turned off, the capacitor 20A can be intermittently charged and the charged charge can be used. In addition, since the charge accumulated in the capacitor 20A is automatically discharged when the ignition is turned on, it is possible to prevent the characteristics of the capacitor 20A from deteriorating.

[0151] Also in Figure 6 In the illustrated in-vehicle power supply system 10C, cost increases can be prevented by connecting the auxiliary device system battery 13B only to the second power line 52. By using a dark current regulator 15d in the zone ECU 15, it is possible to supply dark current required to power small power loads 18 when the ignition is off and the DC / DC converter 16 is stopped. Using a dedicated dark current regulator 15d significantly reduces power loss when the ignition is off, compared to using a DC / DC converter 16.

[0152] The present invention is not limited to the above-described embodiments and can be appropriately modified, improved, etc. In addition, the materials, shapes, sizes, numbers, arrangement positions, etc. of the components in the above-described embodiments are optional and not limited as long as the present invention can be achieved.

[0153] The characteristic features related to the above-mentioned vehicle power supply system will be briefly summarized and listed in the following [1] to [5].

[0154] [1] An on-vehicle power supply system (10A) that supplies power from a vehicle side power supply to an on-vehicle device serving as a load on the vehicle, the on-vehicle power supply system comprising:

[0155] a main battery (auxiliary device system battery 13 ) configured to charge and discharge power supply electric power;

[0156] a host power supply unit (power control unit PCU) configured to supply power to the main battery;

[0157] a first power line (51) configured to be energized with power supply power of a first voltage (e.g., 12V), which is a relatively low voltage;

[0158] a second power line (52) configured to be energized with power at a second voltage (e.g., 48V) that is higher than the first voltage;

[0159] a voltage conversion unit (DC / DC converter 16 ) configured to convert the voltage of the power supply electric power between the first power supply line and the second power supply line; and

[0160] capacitor (20), wherein

[0161] The main battery, the upper power supply unit, and the voltage conversion unit are connected to the first power supply line, and the capacitor and the voltage conversion unit are connected to the second power supply line.

[0162] According to the in-vehicle power supply system having the configuration of [1] described above, the power generated by boosting the power of the first power line by the voltage conversion unit is supplied to a large power load, making it easy to reduce the diameter of the wires at the location of the second power line, etc. and to reduce the size of the terminals. By connecting the main battery only to the first power line side, it is possible to prevent cost increases.

[0163] [2] The vehicle-mounted power supply system according to [1] further includes:

[0164] a switching unit (switching circuit SW1 ) configured to control a circuit connection between the capacitor and the second power supply line; and

[0165] A control unit (main ECU 30A) configured to control the switch unit, wherein

[0166] In association with the vehicle's ignition device being switched off, the control unit controls the switch unit and performs discharge of the capacitor (S20), and when it is necessary to supply power to at least a large power load in the ignition device-on state, the control unit controls the switch unit and releases the charge accumulated in the capacitor (S16).

[0167] According to the in-vehicle power supply system having the configuration of [2] described above, it is possible to prevent electric charge from being accumulated in the capacitor for a long period of time, thereby preventing deterioration of the capacitor.

[0168] [3] An on-vehicle power supply system (10B) that supplies power from a vehicle side power supply to an on-vehicle device serving as a load on the vehicle, the on-vehicle power supply system comprising:

[0169] a main battery (auxiliary device system battery 13B) configured to charge and discharge power supply electric power;

[0170] a host power supply unit (power control unit PCU) configured to supply power to the main battery;

[0171] a first power line (51) configured to be energized with power supply power of a first voltage (e.g., 12V), which is a relatively low voltage;

[0172] a second power line (52) configured to be energized with power at a second voltage (e.g., 48V) that is higher than the first voltage;

[0173] a voltage conversion unit (DC / DC converter 16 ) configured to convert the voltage of the power supply electric power between the first power supply line and the second power supply line; and

[0174] Capacitor (20A), where

[0175] The upper power supply unit, the voltage conversion unit, and the capacitor are connected to the first power supply line, and the main battery and the voltage conversion unit are connected to the second power supply line.

[0176] According to the vehicle power supply system having the configuration of [3] above, dark current required for powering small power loads when the ignition is turned off can be supplied from the capacitor. Therefore, power loss occurring in the voltage conversion unit when the ignition is turned off can be reduced.

[0177] [4] The vehicle-mounted power supply system according to [3] further includes:

[0178] a switching unit (switch circuits SW2, SW3) configured to control a circuit connection between the capacitor and the first power supply line; and

[0179] A control unit (main ECU 30B) configured to control the switch unit, wherein

[0180] When a predetermined condition is satisfied while the ignition of the vehicle is off, the control unit controls the switch unit and performs charging of the capacitor ( S32 , S33 ), and when the ignition is on, the control unit controls the switch unit and performs discharging of the capacitor ( S34 ).

[0181] According to the in-vehicle power supply system having the configuration of [4] above, when the ignition is turned off, the capacitor can be intermittently charged and the charged charge can be used. In addition, since the charge accumulated in the capacitor is automatically discharged when the ignition is turned on, it is possible to prevent the characteristics of the capacitor from deteriorating.

[0182] [5] An on-vehicle power supply system (10C) that supplies power from a vehicle to an on-vehicle device serving as a load on the vehicle, the on-vehicle power supply system comprising:

[0183] a main battery (auxiliary device system battery 13B) configured to charge and discharge power supply electric power;

[0184] a host power supply unit (power control unit PCU) configured to supply power to the main battery;

[0185] a first power line (51) configured to be energized with power supply power of a first voltage (e.g., 12V), which is a relatively low voltage;

[0186] a second power line (52) configured to be energized with power at a second voltage (e.g., 48V) that is higher than the first voltage;

[0187] a voltage conversion unit (DC / DC converter 16 ) configured to convert the voltage of the power supply electric power between the first power supply line and the second power supply line; and

[0188] A dark current supply circuit (dark current regulator 15d) is connected in parallel with the voltage conversion unit, wherein

[0189] The upper power supply unit, the voltage conversion unit, and the dark current supply circuit are connected to the first power supply line, and the main battery, the voltage conversion unit, and the dark current supply circuit are connected to the second power supply line, and

[0190] The dark current supply circuit supplies power generated by boosting a voltage of the second power line to the first power line as dark current when an ignition of the vehicle is turned off.

[0191] According to the in-vehicle power supply system having the configuration of [5] described above, by using a dedicated dark current supply circuit, the power loss occurring when the ignition is turned off can be significantly reduced compared to the case of using a voltage conversion unit.

Claims

1. A vehicle-mounted power supply system for supplying vehicle-side power to a vehicle-mounted device serving as a load on the vehicle, the vehicle-mounted power supply system comprising: a main battery configured to charge and discharge power from the power supply; an upper power supply unit configured to supply power to the main battery; a first power line assigned to be energized with power supply power at a first voltage, the first voltage being a relatively low voltage; a second power line assigned to be energized with power at a second voltage, the second voltage being higher than the first voltage; a voltage conversion unit configured to convert a voltage of power supply power between the first power line and the second power line; capacitors; a switch unit configured to control a circuit connection between the capacitor and the first power line; as well as A control unit configured to control the switch unit, wherein The upper power supply unit, the voltage conversion unit, and the capacitor are respectively connected to the first power line, and the main battery and the voltage conversion unit are connected to the second power line, The control unit controls the switching unit and intermittently performs charging of the capacitor while an ignition of the vehicle is turned off, and controls the switching unit and performs discharging of the capacitor while the ignition is turned on.

2. A vehicle-mounted power supply system for supplying vehicle-side power to a vehicle-mounted device serving as a load on the vehicle, the vehicle-mounted power supply system comprising: a main battery configured to charge and discharge power from the power supply; an upper power supply unit configured to supply power to the main battery; a first power line assigned to be energized with power supply power at a first voltage, the first voltage being a relatively low voltage; a second power line assigned to be energized with power at a second voltage, the second voltage being higher than the first voltage; a voltage conversion unit configured to convert a voltage of power supply power between the first power line and the second power line; as well as A dark current supply circuit is connected in parallel with the voltage conversion unit, wherein: The upper power supply unit, the voltage conversion unit, and the dark current supply circuit are connected to the first power line, and the main battery, the voltage conversion unit, and the dark current supply circuit are connected to the second power line, and The dark current supply circuit supplies power generated by stepping down a voltage of the second power line to the first power line as dark current when an ignition of the vehicle is turned off.

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