Vehicle power supply system

Abstract

This vehicle power supply system comprises: an auxiliary battery provided as a power supply for auxiliary machinery in a vehicle; a relay interposed between the auxiliary battery and the auxiliary machinery; a control part that controls the relay to be turned off according to a decrease in the remaining amount of the auxiliary battery and performs capacity-decrease-time interruption control for interrupting power supply from the auxiliary battery to the auxiliary machinery; and a light detector that detects light. The control part performs control for turning on the relay when light of a prescribed lighting pattern is detected by the light detector in a state where the relay is turned off.

Description

Vehicle power supply system

[0001] The present invention relates to the technical field of a vehicle power supply system provided with a battery for supplying power to auxiliary devices in a vehicle.

[0002] As a substitute for a 12V lead battery for auxiliary devices, the use of a lithium-ion battery has been considered.

[0003] Regarding related prior art, Patent Document 1 below can be cited. Patent Document 1 below discloses a technique for improving the safety of a vehicle by ensuring power supply in an emergency such as a vehicle crash.

[0004] Japanese Unexamined Patent Application Publication No. 2022-167433

[0005] Here, when a lithium-ion battery is used as the auxiliary battery, the behavior when the battery is fully charged is different from that when a lead battery is used. In the case of a lithium-ion battery, a control unit called a BMS (Battery Management System) for protecting the battery cells is mounted. When the battery cells are not charged for some reason and the SOC (State Of Charge) as the remaining battery level decreases, a relay function (called SMR: System Main Relay) that self-shuts off the power is implemented to prevent the battery from entering an irreversibly non-reusable state.

[0006] However, due to the function of this SMR, the power of auxiliary devices including various in-vehicle ECUs (Electric Control Unit) is lost, so even if repair or recharging is desired, the vehicle cannot be restarted. At this time, since the power supply of the auxiliary devices is lost, the diagnostic tool cannot be used either.

[0007] Therefore, when attempting to recharge and reuse a lithium-ion battery, it is necessary to either connect a separate power source to the vehicle to power the diagnostic tool and send a restart command to the BMS, or, if there is no separate power source near the vehicle, remove the lithium-ion battery and send a restart command to the BMS in an environment where power can be supplied, or replace the lithium-ion battery with a new one. These measures complicate the work and lead to increased repair costs.

[0008] This invention has been made in view of the above circumstances, and aims to prevent the handling of battery failure from becoming complicated and to prevent a decrease in maintainability.

[0009] A vehicle power supply system according to one aspect of the present invention comprises: an auxiliary battery provided as a power source for auxiliary equipment in a vehicle; a relay inserted between the auxiliary battery and the auxiliary equipment; a control unit that controls the relay to turn off in accordance with the decrease in the remaining charge of the auxiliary battery, thereby cutting off the power supply from the auxiliary battery to the auxiliary equipment; and a photodetector that detects light, wherein the control unit controls the relay to turn on when the photodetector detects light of a predetermined lighting pattern while the relay is off.

[0010] According to the present invention, it is possible to prevent the handling of battery failure from becoming complicated and to prevent a decrease in maintainability.

[0011] This figure shows an example configuration of a vehicle equipped with a vehicle power supply system as an embodiment. This figure is for explaining an example configuration of a vehicle power supply system. This figure shows an example of the arrangement of photodetectors. This is a flowchart of the control unit's processing.

[0012] <1. Configuration of the Vehicle Power Supply System 1> Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. Figure 1 is a diagram showing an example of the configuration of a vehicle 100 equipped with the vehicle power supply system 1 as an embodiment. Note that in Figure 1, only the components according to this embodiment are extracted and shown from among the various components of the vehicle 100 as an embodiment.

[0013] As shown in Figure 1, the vehicle 100 is a Hybrid Electric Vehicle (HEV) equipped with an engine 2 and an MG (motor generator) 4 as drive sources. The vehicle 100 is equipped with a high-voltage battery 5 (driving battery) to supply the driving power to the MG 4. In the HEV vehicle 100, the engine 2 may be used as a drive source for the wheels, or it may be used as a power source to generate power for driving the MG 4 and for charging the high-voltage battery 5.

[0014] In this example, a four-wheeled vehicle is assumed for vehicle 100, but the vehicle in the embodiment may be any vehicle with at least two wheels. Furthermore, vehicle 100 may be a gasoline-powered vehicle equipped only with engine 2 as a drive source, or it may be an electric vehicle equipped only with MG4.

[0015] The vehicle 100 is equipped with an inverter 6 for the MG 4. When the MG 4 is powering, the inverter 6 outputs a drive voltage to the MG 4 based on the input voltage from the high-voltage battery 5, and when the MG 4 is regenerating, it charges the high-voltage battery 5 using the regenerative power from the MG 4.

[0016] Furthermore, the vehicle 100 is equipped with auxiliary equipment 3. The auxiliary equipment 3 broadly includes various electronic components for operating the engine 2, such as fuel injectors and electronic throttles, as well as various ECUs (Electric Control Units) for controlling various vehicle operations, such as the engine 2 and MG4, and onboard electronic equipment such as meters, navigation equipment, and audio equipment.

[0017] The vehicle power supply system 1 includes an auxiliary battery unit 10 for supplying power to such auxiliary equipment 3. The auxiliary battery unit 10 has an auxiliary battery 11 provided as a power source for the auxiliary equipment 3. The rated output voltage of the auxiliary battery 11 is 12V. However, the rated output voltage of the auxiliary battery 11 may be 24V, for example, and is not limited to 12V. The rated output voltage of the auxiliary battery 11 is lower than the rated output voltage of the high-voltage battery 5 (for example, 400V).

[0018] The auxiliary battery 11 is a secondary battery, and a lithium-ion battery is used. Compared to lead-acid batteries, lithium-ion batteries can be made smaller and lighter in terms of battery weight and size, and have advantages in terms of reducing vehicle weight and installation space.

[0019] In vehicle 100, the auxiliary battery 11 can be charged by the high-voltage battery 5. When the auxiliary battery 11 is charged by the high-voltage battery 5, a DC / DC converter 7 is used. The DC / DC converter 7 has a step-down function and charges the auxiliary battery 11 by stepping down the input voltage from the high-voltage battery 5 to 12V and outputting it to the auxiliary battery unit 10.

[0020] Figure 2 is a diagram illustrating an example configuration of the vehicle power supply system 1. In addition to the example configuration of the vehicle power supply system 1, Figure 2 also shows the auxiliary equipment 3, high-voltage battery 5, and DC / DC converter 7 shown in Figure 1.

[0021] Here, the connector section 22 shown in Figure 2 has various terminals formed for connecting a diagnostic device, for example, a CAN (Controller Area Network) terminal is formed therein. When a CAN communication device such as a diagnostic device is connected to the connector section 22, it is possible to supply power to the communication device from the vehicle power supply system 1 side via the connector section 22.

[0022] As shown in Figure 2, the vehicle power supply system 1 includes an auxiliary battery unit 10 and a photodetector 20.

[0023] The auxiliary battery unit 10 comprises an auxiliary battery 11, a relay 12, and a control unit 13. The auxiliary battery unit 10 also has terminals including a positive terminal Tp, a negative terminal Tm, a data terminal Td, a switch signal terminal Ts, and a GND (ground) terminal Tg.

[0024] Outside the auxiliary battery unit 10, as shown in the figure, the auxiliary components 3 are inserted between the positive terminal Tp and the negative terminal Tm, which is grounded to GND. Similarly, the DC / DC converter 7 and the high-voltage battery 5 are also inserted between the positive terminal Tp and the negative terminal Tm.

[0025] Within the auxiliary battery unit 10, a series connection circuit between the relay 12 and the auxiliary battery 11 is inserted between the positive terminal Tp and the negative terminal Tm. The relay 12 is configured as an electromagnetic relay, and its on / off switching is controlled by the control unit 13.

[0026] In the vehicle power supply system 1, when the relay 12 is ON, the auxiliary battery 11 and the positive terminal Tp are electrically connected, and power from the auxiliary battery 11 can be supplied to the auxiliary equipment 3. In addition, in the vehicle power supply system 1, the electrical connection between the auxiliary battery 11 and the positive terminal Tp makes it possible to supply power from the high-voltage battery 5 to the auxiliary battery 11 via the DC / DC converter 7.

[0027] On the other hand, in the vehicle power supply system 1, when the relay 12 is turned off, the auxiliary battery 11 and the positive terminal Tp become electrically disconnected, making it impossible to supply power from the auxiliary battery 11 to the auxiliary equipment 3. Furthermore, in the vehicle power supply system 1, it also becomes impossible to charge the auxiliary battery 11 with the high-voltage battery 5.

[0028] The control unit 13 is configured with a microcomputer having, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU performs various processes according to the program stored in the ROM, thereby performing various controls on the auxiliary battery unit 10. Although not shown in the diagram, the control unit 13 operates by being powered by the auxiliary battery 11.

[0029] The control unit 13 can communicate data with external devices such as diagnostic equipment connected to the connector unit 22 via the data terminal Td. The control unit 13 can also communicate data with an ECU (Electric Control Unit) (not shown) via the data terminal Td. Furthermore, the control unit 13 can execute processing based on external instructions, such as commands sent by a diagnostic equipment.

[0030] Furthermore, the control unit 13 has a function for monitoring the status of the auxiliary battery 11. For example, the control unit 13 monitors the output voltage value, output current value, battery temperature, etc., of the auxiliary battery 11, and calculates the State of Charge (SOC) and State of Health (SOH).

[0031] Furthermore, the control unit 13 also controls the relay 12 based on the status monitoring results of the auxiliary battery 11. Specifically, the control unit 13 controls the relay 12 to turn off in response to a decrease in the remaining charge of the auxiliary battery 11, thereby performing capacity-reducing cutoff control to cut off the power supply from the auxiliary battery 11 to the auxiliary equipment 3. For example, the control unit 13 controls the relay 12 to turn off in response to the detection that the State of Charge (SOC) of the auxiliary battery 11 has fallen below a predetermined threshold (e.g., 10%). Note that the conditions for turning off the relay 12 in capacity-reducing cutoff control are not limited to the condition that the SOC falls below a predetermined threshold. For example, a temporal element may be incorporated, and the condition may be that the state in which the SOC is below a predetermined threshold has elapsed for a predetermined time or longer. Alternatively, a frequency condition may be incorporated, and the condition may be that the number of times the SOC falls below a certain value per unit time is greater than or equal to a predetermined number. Furthermore, other conditions can also be defined.

[0032] By performing the capacity reduction shutdown control described above, when a lithium-ion battery is used as the auxiliary battery 11, it is possible to prevent the auxiliary battery 11 from becoming irreversibly unusable.

[0033] If the capacity-reducing shutdown control is performed, power to the auxiliary equipment 3, including various ECUs, will be lost, making it impossible to restart the vehicle 100 even when repairs or recharging are desired. Therefore, when attempting to recharge and reuse the auxiliary battery 11, it is conceivable to connect a separate power source to the vehicle 100 to enable power supply to the diagnostic tool and send a restart command to the control unit 13. Alternatively, if there is no separate power source near the vehicle 100, it is conceivable to remove the auxiliary battery unit 10 and send a restart command to the control unit 13 in an environment where power can be supplied. It is also conceivable to take measures such as replacing the auxiliary battery unit 10 with a new one. However, in any case, this leads to increased complexity of the work and increased repair costs.

[0034] Therefore, in this embodiment, a photodetector 20 for detecting light is provided, and the control unit 13 controls the relay 12 to turn on when the photodetector 20 detects light of a predetermined lighting pattern while the relay 12 is off. As a result, even when power supply to the auxiliary equipment 3 is stopped due to a capacity-low cutoff control for the protection of the auxiliary battery 11, the relay 12 will be forcibly turned on when the user illuminates the photodetector 20 with light of a predetermined lighting pattern, enabling power supply to the auxiliary equipment 3.

[0035] In the vehicle power supply system 1, once power can be supplied to the auxiliary equipment 3, the auxiliary battery 11 can be charged by the high-voltage battery 5, and thereafter, power can be supplied from the auxiliary battery 11 to the auxiliary equipment 3 as usual. In other words, in this case, the only action required to deal with a dead battery is for the user to illuminate the photodetector 20 with light of a predetermined lighting pattern. In this way, even when a lithium-ion battery is provided as the auxiliary battery 11, it is possible to prevent the procedures for dealing with a dead battery from becoming complicated.

[0036] Here, a photodiode can be used as the photodetector 20. A photodiode flows a current proportional to the intensity (illuminance) of the light it receives. When no light is irradiated, the photodiode is in an off state and does not flow any current. On the other hand, when light is irradiated, the photodiode flows a current proportional to the intensity of that light.

[0037] In the vehicle power supply system 1, a signal supply unit 21 is formed to supply a switch signal to the control unit 13 according to the intensity of light irradiated onto the photodetector 20. The anode of the photodetector 20 is connected to the control unit 13 via the switch signal terminal Ts. The line connecting the anode of the photodetector 20 to the control unit 13 via the switch signal terminal Ts is referred to as the positive electrode line. The cathode of the photodetector 20 is connected to the control unit 13 via the GND terminal Tg. The line connecting the cathode of the photodetector 20 to the control unit 13 via the GND terminal Tg is referred to as the negative electrode line.

[0038] The signal supply unit 21 includes a resistor Ru as a pull-up resistor connected to the positive terminal line and a resistor Rd as a pull-down resistor connected to the negative terminal line. A 12V voltage from the auxiliary battery 11 is supplied to the pull-up resistor Ru. This prevents the photodetector 20 from being mistakenly determined to be ON when the positive terminal line is short-circuited to GND. In other words, it prevents the relay 12 from being stuck ON when GND is short-circuited, and prevents power from being mistakenly supplied from the auxiliary battery 11 to the auxiliary equipment 3 under the capacity reduction cutoff control.

[0039] The control unit 13 detects the voltage of the positive electrode line, which is input based on the current value that flows according to the intensity of the light received by the photodetector 20, and determines whether the photodetector 20 is in an ON state when light of an intensity equal to or greater than a predetermined intensity threshold is irradiated onto it. As described above, the photodetector 20 flows a current amount corresponding to the intensity of the light it receives, so the voltage of the positive electrode line changes depending on the amount of current flowing to the photodetector 20, that is, the intensity of the light received by the photodetector 20. Therefore, the control unit 13 can detect the intensity of the light received by the photodetector 20 by detecting the voltage of the positive electrode line. Based on the voltage of the positive electrode line, the control unit 13 determines that the photodetector 20 is in an ON state when the intensity of the light received by the photodetector 20 is equal to or greater than a predetermined intensity threshold, and that it is in an OFF state when the intensity of the light irradiated onto the photodetector 20 is less than a predetermined intensity threshold.

[0040] The control unit 13 then controls the relay 12 to turn on when the photodetector 20 detects light of a predetermined lighting pattern. For example, the control unit 13 turns on the relay 12 if the photodetector 20 detects flashing of light at or above an intensity threshold at least a predetermined number of times (e.g., 3 times) within a predetermined time (e.g., 3 seconds). In other words, the control unit 13 turns on the relay 12 if the number of times the photodetector 20 has been turned on within a predetermined time is greater than or equal to a predetermined number.

[0041] Thus, even when the photodetector 20 is turned on by receiving sunlight or unintended light, the relay 12 will not be immediately turned on, so that the possibility of the relay 12 being erroneously turned on can be reduced.

[0042] In addition, when a predetermined exception condition is satisfied, the control unit 13 maintains the relay 12 in the off state regardless of whether the photodetector 20 is in the on state or the off state. Specifically, when a predetermined exception condition that may lead to a battery failure, such as overcurrent, overcharge, high temperature, or overdischarge of the auxiliary battery 11, is satisfied while the relay 12 is in the off state, the control unit 13 maintains the relay 12 in the off state even when the photodetector 20 detects light of a predetermined lighting pattern. Thereby, failure of the auxiliary battery 11 can be prevented, and safety can be improved.

[0043] FIG. 3 is a diagram showing an example of the arrangement of the photodetector 20. The photodetector 20 may be installed at a position where a user such as a driver can receive light irradiated from an LED light of a portable terminal such as a smartphone. Further, the photodetector 20 may be arranged at a position where it does not receive, or hardly receives, sunlight or unintended light.

[0044] Specifically, as shown in FIG. 3, the photodetector 20 may be installed inside the doorknob 31 provided on the driver's side door 30 such that the light receiving surface faces the ground side from the horizontal direction. By being installed in this way, the photodetector 20 can be prevented from being directly irradiated by sunlight being blocked by the doorknob 31. Further, the photodetector 20 can also be prevented from being directly irradiated by light such as streetlights.

[0045] In addition, the user can irradiate the photodetector 20 with the light of the LED light by inserting the portable terminal into the inside of the doorknob 31 so that the LED light of the portable terminal faces the photodetector 20. Therefore, the photodetector 20 can be switched on and off only by the light of the intentionally directed LED light.

[0046] Figure 4 is a flowchart of the processing of the control unit 13. The control unit 13 executes the processing shown in Figure 4 when the relay 12 is in the off state.

[0047] First, in step S1, the control unit 13 detects the on / off state of the photodetector 20 based on the voltage of the positive electrode side line. In the subsequent step S2, the control unit 13 determines whether the photodetector 20 has detected light of a predetermined lighting pattern based on the on / off state of the photodetector 20.

[0048] If the photodetector 20 has not detected light of a predetermined lighting pattern (No in step S2), the process returns to step S1. On the other hand, if the photodetector 20 has detected light of a predetermined lighting pattern (Yes in step S2), in step S3, the control unit 13 determines whether an exception condition is satisfied. Specifically, taking the overcurrent, overcharge, high temperature, and overdischarge of the auxiliary battery 11 exemplified above as exception conditions, it is determined whether any of these conditions is satisfied.

[0049] If it is determined that the exception condition is not satisfied (No in step S3), the control unit 13 controls the relay 12 to be turned on in step S4.

[0050] On the other hand, if it is determined that the exception condition is satisfied (Yes in step S3), the control unit 13 maintains the relay 12 in the off state in step S5.

[0051] In response to executing either the process of step S4 or S5, the control unit 13 ends the series of processes shown in Figure 3.

[0052] <2. Modified Example> The above embodiments are examples of implementing the present invention, and the implementation of the present invention is not limited to the above examples, and various modified examples can be considered.

[0053] For example, in the above-described embodiment, the case where a lithium-ion battery is used as the auxiliary battery 11 is exemplified. However, the auxiliary battery 11 is not limited to a lithium-ion battery, and any battery that can be the target of cut-off control during capacity reduction may be used.

[0054] Furthermore, in the embodiment described above, the predetermined lighting pattern detected by the photodetector 20 for controlling the relay 12 to turn on was described as a predetermined number of flashes within a predetermined time. However, the predetermined lighting pattern may also be the photodetector 20 being in the ON state for a predetermined time or longer, or it may be any other lighting state.

[0055] Furthermore, in the embodiment described above, the photodetector 20 is provided inside the door handle 31 of the door 30. However, the photodetector 20 may also be provided inside the door handle of any door other than the driver's side. Alternatively, it may be provided at a predetermined location on the exterior of the vehicle 100, such as the outer wall of the vehicle 100, where the user can shine light.

[0056] <3. Summary> As described above, the vehicle power supply system 1 of the embodiment includes an auxiliary battery 11 provided as a power source for auxiliary equipment 3 in the vehicle 100, a relay 12 inserted between the auxiliary battery 11 and the auxiliary equipment 3, a control unit 13 that controls the relay 12 to turn off in accordance with the decrease in the remaining charge of the auxiliary battery 11, thereby cutting off the power supply from the auxiliary battery 11 to the auxiliary equipment 3, and a photodetector 20 that detects light. The control unit 13 controls the relay 12 to turn on when the photodetector 20 detects light of a predetermined lighting pattern while the relay 12 is off. As a result, even when the power supply to the auxiliary equipment 3 is stopped due to the capacity-decreasing cutoff control for the protection of the auxiliary battery 11, if the user shines light on the photodetector 20 in a predetermined lighting pattern, the relay 12 will be forcibly turned on, and power supply to the auxiliary equipment 3 will be possible. Therefore, even when a lithium-ion battery is provided as an auxiliary battery 11, it is possible to prevent the work required to deal with a dead battery from becoming complicated, and to prevent a decrease in maintainability compared to when a conventional lead-acid battery is used. Here, in a vehicle 100 that does not have a physical key, that is, a vehicle 100 in which the door 30 is unlocked by an electrical signal, if the relay 12 is turned off and power is not supplied to the auxiliary equipment 3, the door 30 cannot be unlocked. Even in such a vehicle 100, the user can turn on the relay 12 by shining light from outside the vehicle 100 toward the photodetector 20, thereby supplying power to the auxiliary equipment 3 and unlocking the door 30.

[0057] The photodetector 20 is positioned at a predetermined location on the vehicle's exterior where it is not directly exposed to sunlight. This reduces the likelihood of the photodetector 20 being turned on by sunlight. In other words, the control unit 13 can perform on / off control of the relay 12 with greater precision.

[0058] The photodetector 20 is positioned inside a door handle 31 located on one of the doors 30 of the vehicle 100. This reduces the amount of sunlight that directly shines on the photodetector 20, and also allows the user to easily shine light on the photodetector 20 using a mobile device or the like.

[0059] The control unit 13 controls the relay 12 to turn on when the photodetector 20 detects light in a flashing pattern. This prevents the relay 12 from being turned on even if the photodetector 20 is turned on by sunlight or other unintended light, allowing the control unit 13 to control the relay 12 on and off with greater precision.

[0060] The control unit 13 controls the relay 12 to turn on when the photodetector 20 detects flashing light at least a predetermined number of times within a predetermined period. This prevents the relay 12 from being turned on by unintended flashing light, and allows the control unit 13 to control the relay 12 on and off with greater precision.

[0061] 1. Vehicle power supply system 3. Auxiliary equipment 10. Auxiliary battery unit 11. Auxiliary battery 12. Relay 13. Control unit 20. Photodetector

Claims

1. A vehicle power supply system comprising: an auxiliary battery provided as a power source for auxiliary equipment in a vehicle; a relay inserted between the auxiliary battery and the auxiliary equipment; a control unit that controls the relay to turn off in accordance with the decrease in the remaining charge of the auxiliary battery, thereby cutting off the power supply from the auxiliary battery to the auxiliary equipment; and a photodetector that detects light, wherein the control unit controls the relay to turn on when the photodetector detects light of a predetermined lighting pattern while the relay is in the off state.

2. The vehicle power supply system according to claim 1, wherein the photodetector is positioned at a predetermined location on the exterior of the vehicle where it is not directly exposed to sunlight.

3. The vehicle power supply system according to claim 2, wherein the photodetector is positioned inside a door handle provided on one of the doors of the vehicle.

4. The vehicle power supply system according to any one of claims 1 to 3, wherein the control unit controls the relay to turn on when the photodetector detects flashing light.

5. The vehicle power supply system according to claim 4, wherein the control unit controls the relay to turn on when the photodetector detects flashing light at least a predetermined number of times within a predetermined period.

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