power supply

Abstract

To provide a power supply which can suppress battery deterioration with guaranteed backup control.SOLUTION: The power supply includes a first system, a second system, an inter-system switch, a power switch and a control unit. The power of a first power supply is supplied to a first load through the first system. The power of a second power supply is supplied to a second load through the second system. The inter-system switch connects or disconnects between the first and the second systems. The power switch connects or disconnects between the second power supply and the second system. The control unit, on detection of a power failure of the first system, performs backup control which cuts off the inter-system switch and connects the power switch to supply power from the second power supply to the second load, and also performs charge control so that the charge state of the second power supply becomes a set value or higher in which the backup control becomes executable. The control unit sets a set value to be lower as the temperature of the second power supply is higher, and sets to a value close to the minimum electric energy required for the backup control.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device. [Background technology]

[0002] Conventionally, there is a technology that has multiple power supply systems, and if one of the power supply systems fails while the vehicle is running, the other power supply system is switched over to supply power to the onboard equipment, allowing the vehicle to evacuate to a safe location. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-62727 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above technology, in preparation for a power supply failure, it is necessary to perform charge control so that the charge state of the power supply in the other power supply system is maintained at a charge state that allows backup control. However, since power supplies such as lithium-ion batteries tend to deteriorate more rapidly as temperatures increase, there is a risk that battery deterioration will increase if the charge state is maintained near full charge under high-temperature conditions, for example.

[0005] The present invention has been made in view of the above, and has an object to provide a power supply device that can suppress battery degradation while ensuring backup control. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the power supply device of the present invention includes a first system, a second system, an inter-system switch, a power switch, and a control unit. The first system supplies power from a first power source to a first load. The second system supplies power from a second power source to a second load. The inter-system switch connects or disconnects the first system and the second system. The power switch connects or disconnects the second power source and the second system. When a power failure of the first system is detected, the control unit performs backup control to supply power from the second power source to the second load by disconnecting the inter-system switch and connecting the power switch, and also performs charge control to maintain the state of charge of the second power source at or above a set value at which the backup control can be executed. The control unit sets the set value lower as the temperature of the second power source increases, and sets it to a value close to the minimum amount of power required for the backup control. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress battery degradation while ensuring backup control. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an autonomous driving system including a power supply device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the operation of backup control. [Figure 3] FIG. 3 is a diagram illustrating an example of the operation of the charging control. [Figure 4] FIG. 4 is a diagram showing the amount of deterioration of the second power supply for each combination of SOC and temperature. [Figure 5] FIG. 5 is a flowchart showing the procedure of the charge control process executed by the power supply device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the power supply device disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below. The power supply device according to the embodiment is mounted on a vehicle having an automatic driving function and supplies power to a load related to the automatic driving control.

[0010] 1 is a diagram showing an example of the configuration of an autonomous driving system S including a power supply device 1 according to an embodiment. As shown in FIG. 1, the autonomous driving system S includes the power supply device 1, a first power source 10, a vehicle control device 100, a first load 101, and a second load 102.

[0011] The first load 101 includes a load related to autonomous driving. For example, the first load 101 includes a steering motor, an electric brake device, an on-board camera, a radar, etc. that operate during autonomous driving. Note that the first load 101 may also include general loads that are not related to autonomous driving, such as a display, an air conditioner, an audio system, a video system, and various lights.

[0012] The second load 102 includes a load related to autonomous driving. For example, the first load 101 includes a steering motor, an electric brake device, an in-vehicle camera, a radar, and the like that operate during autonomous driving.

[0013] The vehicle control device 100 is a control device that operates a first load 101 and a second load 102 to perform automatic driving control of a vehicle.

[0014] The first power source 10 includes a DC / DC converter 11 (hereinafter referred to as DC / DC 11) and a lead battery 12 (hereinafter referred to as PbB 12). The battery of the first power source 10 may be any secondary battery other than PbB 12.

[0015] The DC / DC converter 11 is connected upstream to a generator (not shown) that converts the vehicle's regenerative energy into electric power to generate electricity, and transforms and outputs the input voltage from the generator. If the vehicle is equipped with an engine, the generator may be an alternator that converts the rotational force of the engine into electric power to generate electricity. The DC / DC converter 11 charges the PbB 12, supplies electric power to the first load 101, supplies electric power to the second load 102, and charges the second power source 20 (described later).

[0016] The power supply device 1 is a device that controls the power supply to a first load 101 and a second load 102. As shown in Fig. 1, the power supply device 1 includes a second power source 20, an inter-system switch 4, a control unit 31, a storage unit 32, and voltage sensors 51 and 52.

[0017] The second power source 20 is a backup power source in case the first power source 10 is unable to supply power. The second power source 20 includes a lithium ion battery 21 (hereinafter referred to as "LiB21") and a power source switch 22. The power source switch 22 connects the LiB21 and the second load 102 so that they can be connected / disconnected. The battery of the second power source 20 may be any secondary battery other than the LiB21.

[0018] The power supply device 1 also includes a first system 110 that supplies power from the first power source 10 to the first load 101, and a second system 120 that supplies power from the second power source 20 to the second load .

[0019] The inter-system switch 4 connects the first system 110 and the second system 120 in a connectable / disconnectable manner.

[0020] The voltage sensor 51 is connected between the first power source 10 and the first load 101, and detects the voltage value of the first system 110. The voltage sensor 52 is connected between the second power source 20 and the second load 102, and detects the voltage value of the second system 120.

[0021] The control unit 31 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various other circuits. The control unit 31 may be configured with hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). The storage unit 32 is configured with a storage device such as a non-volatile memory, data flash, or hard disk drive. Various programs and the like are stored in the storage unit 32.

[0022] The control unit 31 controls the operation of the power supply device 1 by having the CPU execute a program stored in the ROM using the RAM as a work area. The control unit 31 supplies power from the first power source 10 or the second power source 20 to the first load 101 and the second load 102 by controlling the on / off of the inter-system switch 4 and the power switch 22 based on detection results (voltage values) input from the voltage sensors 51 and 52. The control unit 3 also has a battery monitoring function for the LiB 21. Specifically, the LiB 21 is provided with a measuring device (not shown), which measures battery parameters such as the voltage, current, and temperature of the LiB 21. The control unit 3 periodically instructs the measuring device to measure the battery parameters via a communication line (not shown), and detects the state of charge (SOC) of the LiB 21 based on the voltage, current, and temperature of the LiB 21 obtained from the measuring device.

[0023] 1 shows an example of control during normal times (normal control) when no abnormality such as a ground fault occurs in the first system 110 and the second system 120. Specifically, during normal control, the control unit 3 turns on the inter-system switch 4 and turns off the power supply switch 22.

[0024] As a result, power is supplied from the first power source 10 to the first load 101 via the first system 110, and power is supplied from the first power source 10 to the second load 102 via the first system 110, the inter-system switch 4, and the second system 120. This normal control is performed whether the vehicle is in automatic or manual driving mode.

[0025] Here, assume that during normal control in automatic operation, the voltage value of voltage sensor 51 drops below a predetermined threshold value (a threshold value at which a ground fault can be determined). In such a case, control unit 31 turns off inter-system switch 4 and turns on power supply switch 22, and identifies whether a ground fault has occurred in first system 110 or second system 120 based on the voltage values ​​of voltage sensors 51 and 52.

[0026] Here, it is assumed that a power failure in the first system 110 is detected because the voltage value of the voltage sensor 51 is below the threshold. In such a case, the power supply device 1 switches to the backup control shown in Fig. 2. Note that if a power failure in the second system 120 is detected because the voltage value of the voltage sensor 52 is below the threshold, the inter-system switch 4 and the power supply switch 22 are turned off, and power is supplied from the first power source 10 to the first load 101, thereby performing evacuation travel control, which will be described later.

[0027] 2 is a diagram showing an example of the operation of backup control. Backup control is a control for supplying power from the second power source 20 of the second system 120 to the second load 102 when power supply from the first power source 10 to the first load 101 and the second load 102 becomes impossible due to a power supply failure in the first system.

[0028] During backup control, the vehicle control device 100 no longer ensures redundancy in power supply during autonomous driving, so by controlling the second load 102, it executes evacuation driving control to evacuate the vehicle during autonomous driving to a safe place such as the shoulder of the road and stop it.

[0029] 2, when a power failure occurs in the first system 110, the control unit 31 turns off the inter-system switch 4 and turns on the power switch 22. Then, the control unit 31 stops the power supply from the first power source 10 to the first load 101 and supplies power from the second power source 20 to the second load 102. In other words, when a power failure occurs in the first system 110, the vehicle control device 100 performs evacuation travel control using only the power from the second power source 20.

[0030] Furthermore, for example, during normal control as shown in Fig. 1, the power supply device 1 performs charge control so that the SOC of the second power source 20 is equal to or greater than a set value at which backup control can be executed. Here, the charge control of the second power source 20 will be described with reference to Fig. 3.

[0031] 3 is a diagram showing an example of the operation of the charging control, which is a control for charging the LiB 21 of the second power source 20 from the above-mentioned generator via the DC / DC 11 of the first power source 10.

[0032] As shown in Fig. 3, when the state of charge of the second power source 20 falls below a set value, the control unit 31 performs charging control by turning on the inter-system switch 4 and turning on the power supply switch 22. This allows power to be supplied from the first power source 10 to the second power source 20, and the LiB 21, whose state of charge has fallen below the set value, can be charged to the set value or higher. Note that the control unit 31 charges the LiB 21 until the SOC reaches a charge completion value that is a predetermined value higher than the set value; this point will be described later with reference to Fig. 4.

[0033] Here, the LiB21 in the second power source 20 tends to deteriorate more as the temperature increases. For this reason, if the set value of the state of charge of the LiB21 (or the charge completion value described later) is set to a value close to full charge, for example, under high temperature conditions, the state of charge of the LiB21 may be maintained close to full charge, which may result in significant battery deterioration.

[0034] Therefore, the power supply device 1 according to the embodiment sets this setting value lower as the temperature of the LiB 21 in the second power supply 20 increases, and sets it to a value closer to the minimum amount of power required for backup control.

[0035] 4 is a diagram showing the amount of deterioration of the second power source 20 (LiB 21) for various combinations of SOC and temperature. As shown in FIG. 4, the higher the temperature of the second power source 20 and the higher the SOC of the second power source 20, the greater the amount of deterioration of the second power source 20 tends to be.

[0036] 4 is the lower limit of the temperature at which backup control can be performed. That is, when the temperature of the second power source 20 is lower than the lower limit of the backup temperature, backup control is prohibited. Note that the information on the deterioration amount shown in FIG. 4 can be obtained, for example, from experiments or the manufacturer of the LiB 21.

[0037] Fig. 4 shows the minimum amount of power th1 required for backup control. As shown in Fig. 4, due to the temperature characteristics of the LiB 21, the SOC, which is the minimum amount of power th1, tends to decrease as the temperature increases. The control unit 31 then sets the set value th2 to a value close to the minimum amount of power th1.

[0038] 4, the control unit 31 sets the set value th2 to be lower as the temperature of the second power supply 20 is higher, and sets the set value th2 to a value closer to the minimum power amount th1. In other words, the control unit 31 sets the set value th2 to be equal to or greater than the minimum power amount th1 and within the "deterioration level: medium" range rather than the "deterioration level: large" range.

[0039] As a result, the set value th2 can suppress battery degradation while maintaining the minimum power amount th1 or more, compared to when the charging state is maintained at "large deterioration" (when maintained near full charge). In other words, the power supply device 1 according to the embodiment can suppress battery degradation while ensuring backup control.

[0040] The control unit 31 also sets a set value th2 where the SOC is higher by a predetermined value than the minimum power amount th1. In other words, the set value th2 is a curve obtained by sliding the curve of the minimum power amount th1 toward the higher SOC side (to the right on the page). The curve of the set value th2 is set to fall within the "medium deterioration" region shown in FIG. 4.

[0041] This predetermined value (the difference between the minimum power amount th1 and the set value th2) is a value according to the amount of decrease due to natural discharge after the vehicle is stopped. That is, the control unit 31 sets the set value th2 based on the amount of decrease due to natural discharge after the vehicle is stopped.

[0042] For example, the predetermined value is set to a value that keeps the SOC equal to or greater than the minimum power amount th1 even when the vehicle is stopped for a predetermined period (e.g., several tens of days). This allows the state of charge to be maintained at or greater than the minimum power amount th1 even when the SOC drops due to natural discharge caused by the vehicle being stopped for a predetermined period. Therefore, backup control can be performed immediately when the vehicle is started after being stopped for a predetermined period.

[0043] In addition, the control unit 31 starts charging control when the SOC of the second power source 20 becomes less than the set value th2, and performs charging control to charge the second power source 20 from the set value th2 to a charging completion value th3, which is a value where the SOC is higher by a predetermined value.

[0044] That is, the charge completion value th3 is a curve obtained by sliding the curve of the set value th2 toward the higher SOC side (to the right on the page). The predetermined value corresponding to the charge completion value is set to a value that causes the curve of the charge completion value th3 to fall within the "medium deterioration" region shown in FIG.

[0045] This allows for a slight decrease in SOC between the charge completion value th3 and the set value th2, which is the charge start position, and prevents intermittent repetition of charge control across the set value th2.

[0046] Furthermore, by keeping the charge completion value th3 within the "deterioration level: medium" region, it is possible to prevent the SOC of the second power source 20 from being maintained in the "deterioration level: high" state, thereby suppressing battery deterioration.

[0047] The control unit 31 may predict a change in temperature of the second power source 20 after the vehicle has stopped, and set the set value th2 based on the predicted temperature change. For example, the control unit 31 predicts a decrease (or increase) in the temperature of the second power source 20 based on past temperature changes of the second power source 20 after the vehicle has stopped.

[0048] For example, the control unit 31 predicts the temperature change of the second power source 20 based on the location where the vehicle is parked, the parked time, and the temperature. Specifically, for example, when the vehicle is used for commuting, the control unit 31 predicts the temperature change of the second power source 20 until start-up using the past temperature at home and the parked time (for example, 14 hours from 6:00 PM to 8:00 AM).

[0049] Then, the control unit 31 predicts the temperature of the second power source 20 at the time of starting based on the predicted temperature change, and sets the SOC corresponding to the predicted temperature of the second power source 20 as the set value th2 immediately before the vehicle stops.

[0050] For example, if the control unit 31 predicts that the temperature of the second power source 20 will rise after the vehicle is stopped, it sets the set value th2 to the SOC corresponding to the current temperature (before the vehicle is stopped) or the SOC corresponding to the predicted temperature at the time of starting the vehicle.

[0051] As a result, even if the temperature rises between the time the vehicle is stopped and the time it is started, the SOC of the second power source 20 can be maintained at or above the minimum power amount th1, thereby making it possible to avoid with high precision a situation in which backup control cannot be performed immediately after starting.

[0052] Furthermore, when the control unit 31 predicts that the temperature of the second power source 20 will decrease after the vehicle is stopped, it sets the set value th2 based on the amount of electric energy that can be charged during the period from when the vehicle is started until the transition to automatic driving control. As shown in Fig. 4, when the temperature of the second power source 20 decreases after the vehicle is stopped, the minimum amount of electric energy th1 at the time of starting becomes higher than when the vehicle is stopped.

[0053] For this reason, it is preferable that the set value th2 be set when the vehicle is stopped so that it is equal to or greater than the minimum power consumption th1 at startup; however, depending on the degree of temperature drop, it may be difficult to set a set value th2 that satisfies or exceeds the minimum power consumption th1 at startup.

[0054] On the other hand, since it takes a certain amount of time from when the vehicle starts until it transitions to automatic driving control, charging control can be executed during the period from when the vehicle starts until it transitions to automatic driving control.

[0055] Therefore, when the control unit 31 predicts that the temperature of the second power source 20 will decrease after the vehicle stops, and it is difficult to set the set value th2 that satisfies the minimum amount of power th1 or more at startup, the control unit 31 sets the set value th2 by subtracting the amount of power that can be charged during the period from when the vehicle starts until the transition to automatic driving control. This period is a time that is estimated in advance.

[0056] As a result, even if the SOC of the second power source 20 is less than the minimum power amount th1 at startup, by performing charging control during the period until transitioning to automatic driving control, it is possible to meet the minimum power amount th1 or more at the start of automatic driving.

[0057] Next, the procedure of the charge control process executed in the power supply device 1 according to the embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the procedure of the charge control process executed by the power supply device 1 according to the embodiment.

[0058] 5, first, the control unit 31 detects the temperature of the second power supply 20 (step S101). Next, the control unit 31 sets the set value th2 based on the detected temperature of the second power supply 20 (step S102).

[0059] Next, the control unit 31 detects the SOC of the second power supply 20 (step S103). Next, the control unit 31 determines whether the detected SOC of the second power supply 20 is less than a set value th2 (step S104).

[0060] If the SOC of the second power source 20 is less than the set value th2 (step S104: Yes), the control unit 31 executes charging control by turning on the inter-system switch 4 and the power supply switch 22 (step S105). If the SOC of the second power source 20 is equal to or greater than the set value th2 (step S104: No), the control unit 31 ends the process. In other words, the control unit 31 does not execute charging control.

[0061] Next, the control unit 31 determines whether the SOC of the second power source 20 has reached the charging completion value th3 (step S106). If the SOC of the second power source 20 has reached the charging completion value th3 (step S106: Yes), the control unit 31 ends the charging control (step S107) and ends the process.

[0062] If the SOC of the second power source 20 has not reached the charging completion value th3 (step S106: No), the control unit 31 returns to step S105 and continues charging control until the SOC of the second power source 20 reaches the charging completion value th3.

[0063] As described above, the power supply device 1 according to the embodiment includes the first system 110, the second system 120, the inter-system switch 4, the power switch 22, and the control unit 31. The first system 110 supplies power from the first power source 10 to the first load 101. The second system 120 supplies power from the second power source 20 to the second load 102. The inter-system switch 4 connects or disconnects the first system 110 and the second system 120. The power switch 22 connects or disconnects the second power source 20 and the second system 120. When a power failure in the first system 110 is detected, the control unit 31 performs backup control to supply power from the second power source 20 to the second load 102 by disconnecting the inter-system switch 4 and connecting the power switch 22, and also performs charge control to maintain the state of charge of the second power source 20 at or above a set value th2 at which backup control can be executed. The control unit 31 sets the set value th2 lower as the temperature of the second power source 20 increases, and sets the set value th2 to a value closer to the minimum amount of power th1 required for backup control. This makes it possible to suppress battery degradation while ensuring backup control.

[0064] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0065] 1 Power supply 3. Control Unit 4-system switch 10 1st power supply 11 DC / DC converter 12 Lead-acid battery 20 2nd power supply 21 Lithium-ion battery 22 Power switch 31 Control Unit 32 Storage section 51, 52 Voltage sensor 100 Vehicle control device 101 1st load 102 2nd load 110 1st system 120 2nd system S Autonomous Driving System

Claims

1. a first system in which power from a first power source is supplied to a first load; a second system in which power from a second power source configured with a battery is supplied to a second load; an inter-system switch that connects or disconnects the first system and the second system; a power supply switch that connects or disconnects the second power supply and the second system; a control unit that performs backup control to supply power from the second power source to the second load by turning off the inter-system switch and turning on the power supply switch when a power supply failure of the first system is detected, and charge control to supply power from the first power source to the second power source by turning on the inter-system switch and the power supply switch when the power supply failure is not detected and normal; Equipped with The control unit In the charging control, charging is started when the state of charge of the second power source falls below a first set value that is set to be equal to or greater than the minimum amount of power required for the backup control, and that is set to be lower as the temperature of the second power source increases, and charging is ended when the state of charge reaches a second set value that is higher than the first set value and is set in a region lower than a region where the deterioration amount of the battery is high. A power supply device comprising:

2. The control unit The first set value is set higher than the minimum amount of power by a value corresponding to the amount of decrease due to natural discharge after the vehicle is stopped.

2. The power supply device according to claim 1,

3. The second setting value is The first set value, which is set to be lower as the temperature of the second power source increases, is set to a value that is shifted to a side where the state of charge of the second power source increases.

3. The power supply device according to claim 1 or 2,

4. A power supply control method in which a control device controls a power supply device comprising: a first system in which power from a first power source is supplied to a first load; a second system in which power from a second power source consisting of a battery is supplied to a second load; an inter-system switch that connects or disconnects the first system and the second system; and a power supply switch that connects or disconnects the second power source and the second system, When a power failure of the first system is detected, backup control is performed in which power is supplied from the second power source to the second load by cutting off the inter-system switch and connecting the power switch, and charge control is performed in which power is supplied from the first power source to the second power source by connecting the inter-system switch and the power switch during normal times when the power failure is not detected, In the charging control, charging is started when the state of charge of the second power source falls below a first set value that is set to be equal to or greater than the minimum amount of power required for the backup control, and that is set to be lower as the temperature of the second power source increases, and charging is ended when the state of charge reaches a second set value that is higher than the first set value and is set in a region lower than a region where the deterioration amount of the battery is high. A power supply control method comprising:

5. A power supply control program executed by a computer that controls a power supply device comprising: a first system in which power from a first power source is supplied to a first load; a second system in which power from a second power source consisting of a battery is supplied to a second load; an inter-system switch that connects or disconnects the first system and the second system; and a power supply switch that connects or disconnects the second power source and the second system, When a power failure of the first system is detected, backup control is performed in which power is supplied from the second power source to the second load by cutting off the inter-system switch and connecting the power switch, and charge control is performed in which power is supplied from the first power source to the second power source by connecting the inter-system switch and the power switch during normal times when the power failure is not detected, In the charging control, charging is started when the state of charge of the second power source falls below a first set value that is set to be equal to or greater than the minimum amount of power required for the backup control, and that is set to be lower as the temperature of the second power source increases, and charging is ended when the state of charge reaches a second set value that is higher than the first set value and is set in a region lower than a region where the deterioration amount of the battery is high. A power control program characterized by:

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