Electric power source system

Abstract

To provide an electric power source system enabling the necessity of charging of an auxiliary battery to be optimally determined.SOLUTION: An electric power source system for controlling an auxiliary battery mounted on a vehicle is provided, including a first processing unit that monitors the discharge capacity of an auxiliary battery from its fully charged state, a second processing unit that determines whether the discharge capacity exceeds a threshold determined on the basis of the fully charged capacity and temperature of the auxiliary battery, and a third processing unit that charges the auxiliary battery using the high-voltage battery mounted on the vehicle when the discharge capacity exceeds the threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply system that controls an auxiliary battery mounted on a vehicle. [Background technology]

[0002] Patent Document 1 discloses a power supply system for a vehicle that can charge an auxiliary battery while the vehicle is parked while preventing a delay in starting the vehicle system. This power supply system describes that when the count value of a parking time timer that counts up while the vehicle is parked reaches a predetermined value (for example, a value equivalent to 10 days), the auxiliary battery is charged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-107968 Summary of the Invention [Problem to be solved by the invention]

[0004] In the power supply system described in Patent Document 1, whether or not the auxiliary battery needs to be charged is determined based on timer control. However, the remaining capacity of the auxiliary battery changes dynamically depending on the amount of dark current discharged from the auxiliary battery, the capacity degradation of the auxiliary battery, temperature conditions, etc. Therefore, if the need for charging the auxiliary battery is determined based solely on timer control, as in Patent Document 1, there is a risk that the auxiliary battery will run out of power or the dark current will be limited.

[0005] Therefore, there is room for further study regarding the method for determining whether or not the auxiliary battery needs to be charged.

[0006] The present disclosure has been made in consideration of the above-described problems, and has an object to provide a power supply system that can suitably determine whether or not charging of an auxiliary battery is required. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of the disclosed technology is a power supply system that controls an auxiliary battery mounted on a vehicle, and includes: a first processing unit that monitors the discharge capacity of the auxiliary battery from a fully charged state; a second processing unit that determines whether the discharge capacity exceeds a threshold value determined based on the fully charged capacity and temperature of the auxiliary battery; and a third processing unit that charges the auxiliary battery using a high-voltage battery mounted on the vehicle when the discharge capacity exceeds the threshold value. [Effects of the Invention]

[0008] According to the power supply system of the present disclosure, it is possible to suitably determine whether or not the auxiliary battery needs to be charged by the high-voltage battery based on the discharge capacity and temperature of the auxiliary battery. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a power supply system and a load according to an embodiment of the present disclosure; [Figure 2] Auxiliary battery control process flowchart executed by the power supply system [Figure 3] Example of a map for deriving a discharge capacity threshold from the full charge capacity and temperature of an auxiliary battery DETAILED DESCRIPTION OF THE INVENTION

[0010] The power supply system of the present disclosure performs charging (pumping charging) from the high-voltage battery to the auxiliary battery when it determines that the auxiliary battery, which has been fully charged, has discharged a capacity exceeding a predetermined threshold from the fully charged state, thereby reducing the possibility of the auxiliary battery running out of power. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [composition] Fig. 1 is a block diagram showing a schematic configuration of a power supply system 100 according to an embodiment of the present disclosure and a load 200 that receives power supply from the power supply system 100. The power supply system 100 shown in Fig. 1 includes a high-voltage battery 110, an auxiliary battery 120, a high-voltage DC-DC converter 130, and a B-DC converter 140.

[0012] The configuration shown in FIG. 1 can be mounted on, for example, an electrically powered vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV).

[0013] The high-voltage battery 110 is a secondary battery, such as a lithium-ion battery, that is configured to be chargeable and dischargeable. The high-voltage battery 110 can supply its own stored power to the auxiliary battery 120 and the load 200 via the high-voltage DC-DC converter 130 and the B-DC 140. The high-voltage battery 110 can also store power output by a generator (not shown), such as an alternator. In an electric vehicle, the high-voltage battery 110 corresponds to, for example, a drive battery.

[0014] The auxiliary battery 120 is a secondary battery configured to be rechargeable, such as a lithium-ion battery. The auxiliary battery 120 stores the power output from the high-voltage battery 110 via the high-voltage DC-DC converter 130 and the B-DC 140, and supplies its own stored power to the load 200 via the B-DC 140. The auxiliary battery 120 includes a battery 121, a microcomputer 122, and a temperature sensor 123.

[0015] The battery 121 is, for example, an assembled battery configured by connecting a plurality of battery cells in series and / or parallel. In the following description, to make the comparison with the high-voltage battery 110 easier to understand, the battery 121 itself may be referred to as the "auxiliary battery 120" as necessary.

[0016] The microcomputer 122 is configured to manage the state of the auxiliary battery 120, including the charge / discharge control of the battery 121. The microcomputer 122 acquires the full charge capacity and temperature of the auxiliary battery 120 (acquisition process), and monitors the capacity discharged from the auxiliary battery 120 to the load 200, etc. (hereinafter referred to as "discharge capacity") (monitoring process). The microcomputer 122 also acquires a discharge capacity threshold (described later) based on the full charge capacity and temperature of the auxiliary battery 120 (acquisition process), determines the relationship between the discharge capacity and the discharge capacity threshold (determination process), and requests the B-DC 140 to charge the auxiliary battery 120 (charging process).

[0017] The temperature sensor 123 is a device for detecting the temperature of the battery 121. The temperature of the battery 121 detected by the temperature sensor 123 is output to the microcomputer 122 as the temperature of the auxiliary battery 120.

[0018] The high-voltage DCDC converter 130 is a voltage converter that is provided between the high-voltage battery 110 and the B-DC 140, and converts the input voltage of the high-voltage battery 110 into a voltage required for the auxiliary battery 120 and the load 200, and outputs it to each component via the B-DC 140. For example, a step-down DCDC converter that steps down the voltage of the high-voltage battery 110 and outputs it to the auxiliary battery 120 and the load 200 can be used as this high-voltage DCDC converter 130.

[0019] The B-DC 140 is a configuration (electronic control unit) for comprehensively controlling the exchange of power between the high-voltage battery 110, the auxiliary battery 120, and the load 200. The B-DC 140 includes a microcomputer 141 and a plurality of switches 142.

[0020] The microcomputer 141 is communicably connected to the microcomputer 122 of the auxiliary battery 120 via an in-vehicle network such as a CAN or a direct line. In response to a pumping request (described later) output from the microcomputer 122, the microcomputer 141 controls charging of the auxiliary battery 120 by the high-voltage battery 110, i.e., performs so-called pumping charge control.

[0021] The multiple SWs 142 are switch elements that can switch the electrical connection state (conduction / disconnection) under the control of the microcomputer 141. Note that the number and insertion positions of the SWs included in the B-DC 140 are not limited to those shown in FIG.

[0022] The load 200 is an in-vehicle device that operates on power supplied from the high-voltage battery 110 via the high-voltage DC-DC converter 130 and the B-DC 140, and / or power supplied from the auxiliary battery 120 via the B-DC 140. Note that the number of loads mounted on the vehicle is not limited to the number shown in FIG.

[0023] [control] Next, control performed by the power supply system 100 according to an embodiment of the present disclosure will be described with further reference to Figures 2 and 3. Figure 2 is a flowchart illustrating the processing procedure for auxiliary battery control executed by each component of the power supply system 100. Figure 3 is a diagram showing an example of a map used to derive a discharge capacity threshold from the full charge capacity and temperature of the auxiliary battery 120.

[0024] The auxiliary battery control illustrated in FIG. 2 is started, for example, when the vehicle is parked, and is repeatedly performed until the vehicle is no longer parked.

[0025] (Step S201) The microcomputer 122 of the auxiliary battery 120 monitors the charge / discharge state of the auxiliary battery 120. Specifically, the microcomputer 122 monitors the discharge capacity discharged from the auxiliary battery 120 to the load 200 or the like, that is, the capacity of the auxiliary battery 120 that is reduced from a fully charged state due to the discharge. This monitoring of the auxiliary battery 120 by the microcomputer 122 may be performed continuously, but from the viewpoint of reducing the power consumption of the auxiliary battery 120 while the vehicle is parked, it is desirable to monitor the auxiliary battery 120 intermittently at a predetermined cycle, such as at the time of regular startup.

[0026] When the microcomputer 122 starts monitoring the discharge capacity of the auxiliary battery 120, the process proceeds to step S202.

[0027] (Step S202) The microcomputer 122 of the auxiliary battery 120 acquires a discharge capacity threshold of the auxiliary battery 120. This discharge capacity threshold is acquired by deriving it from a map shown in FIG. 3 based on the current full charge capacity and temperature of the auxiliary battery 120. The temperature of the auxiliary battery 120 can be acquired from a temperature sensor 123. The full charge capacity of the auxiliary battery 120 can be derived using a well-known current integration method or the like. The map in FIG. 3 shows the correspondence relationship between the full charge capacity [Ah] when the auxiliary battery 120 is fully charged and the discharge capacity threshold [Ah] that determines whether charging is necessary to prevent the auxiliary battery 120 from running out, at several temperatures (e.g., 25°C, 0°C, -20°C, and -30°C) within the range of temperatures that the auxiliary battery 120 can be at.

[0028] The map illustrated in FIG. 3 is created based on the following concept. When the full charge capacity of the auxiliary battery 120 decreases due to deterioration, there is a possibility that the auxiliary battery 120 may quickly become low-voltage even with a small amount of discharge, even from a fully charged state. Therefore, the discharge capacity threshold is set low in proportion to the decrease in the full charge capacity, so that the auxiliary battery 120 can be charged even with a small amount of discharge. Furthermore, when the temperature of the auxiliary battery 120 is low, the resistance value increases, making it easier for the voltage of the auxiliary battery 120 to drop. Therefore, the discharge capacity threshold is set low in proportion to the decrease in temperature, so that the auxiliary battery 120 can be charged even with a small amount of discharge, so that a high voltage can be maintained. This setting prevents the auxiliary battery 120 from running out of power or causing dark current limitations.

[0029] When the microcomputer 122 acquires the discharge capacity threshold of the auxiliary battery 120, the process proceeds to step S203.

[0030] (Step S203) The microcomputer 122 of the auxiliary battery 120 determines whether the discharge capacity of the auxiliary battery 120 monitored in step S201 exceeds the discharge capacity threshold of the auxiliary battery 120 acquired in step S202. This determination is made to determine whether the auxiliary battery 120 needs to be charged in order to prevent the auxiliary battery 120 from running out of power or to prevent dark current limitation of the load 200 or the like.

[0031] If the microcomputer 122 determines that the discharge capacity of the auxiliary battery 120 exceeds the discharge capacity threshold (step S203, Yes), the process proceeds to step S204. On the other hand, if the microcomputer 122 determines that the discharge capacity of the auxiliary battery 120 does not exceed the discharge capacity threshold (step S203, No), the process proceeds to step S201.

[0032] (Step S204) The microcomputer 122 of the auxiliary battery 120 requests pumping charge, which is an action of transferring power from the high-voltage battery 110 to the auxiliary battery 120 and charging the auxiliary battery 120. This request is made by the microcomputer 122 outputting a "pumping request" to the microcomputer 141 of the B-DC 140 to request the execution of pumping charge, and the microcomputer 141 receiving this pumping request controls the high-voltage DC-DC converter 130.

[0033] When the microcomputer 122 requests pumping charge of the high voltage battery 110, the process proceeds to step S205.

[0034] (Step S205) In response to a request from the microcomputer 122 of the auxiliary battery 120 , the high-voltage DC-DC converter 130 starts transferring power from the high-voltage battery 110 to the auxiliary battery 120 to charge the auxiliary battery 120 .

[0035] When the high-voltage DC-DC converter 130 starts charging the auxiliary battery 120 from the high-voltage battery 110, the process proceeds to step S206.

[0036] (Step S206) The microcomputer 122 of the auxiliary battery 120 determines whether the auxiliary battery 120 is fully charged or not. Whether the auxiliary battery 120 is fully charged or not can be determined based on the current flowing into the auxiliary battery 120, the output voltage of the auxiliary battery 120, and the like.

[0037] If the microcomputer 122 determines that the auxiliary battery 120 is fully charged (YES in step S206), the process proceeds to step S207. On the other hand, if the microcomputer 122 determines that the auxiliary battery 120 is not fully charged (NO in step S206), the process proceeds to step S205.

[0038] (Step S207) The microcomputer 122 of the auxiliary battery 120 ends the request for pumping charge to the high-voltage battery 110. This request ends when the microcomputer 122 stops outputting the pumping request to the microcomputer 141 of the B-DC 140, and the microcomputer 141, which no longer receives this pumping request, ends control of the high-voltage DC-DC converter 130.

[0039] When the microcomputer 122 ends the request for pumping charge of the high voltage battery 110, the process proceeds to step S208.

[0040] (Step S208) In response to the end of the request from the microcomputer 122 of the auxiliary battery 120, the high-voltage DC-DC converter 130 stops the power transfer from the high-voltage battery 110 to the auxiliary battery 120 and ends the charging of the auxiliary battery 120.

[0041] When the charging of the auxiliary battery 120 from the high-voltage battery 110 by the high-voltage DC-DC converter 130 is completed, the process returns to step S201.

[0042] <Actions and Effects> As described above, according to the power supply system 100 of one embodiment of the present disclosure, the discharge capacity from the fully charged state of the auxiliary battery 120 is monitored, and it is determined whether the discharge capacity exceeds a discharge capacity threshold determined based on the fully charged capacity and temperature of the auxiliary battery 120, and if the discharge capacity exceeds the discharge capacity threshold, the auxiliary battery 120 is charged by the high-voltage battery 110.

[0043] This charging control makes it possible to appropriately determine whether or not the auxiliary battery 120 needs to be charged by the high-voltage battery 110, based on the discharge capacity and temperature of the auxiliary battery 120. This makes it possible to prevent the auxiliary battery 120 from running out of power and to prevent dark current limitations on the load 200, etc.

[0044] One embodiment of the present disclosure has been described above, but the present disclosure can be understood not only as the above-described power supply system, but also as a method executed by a power supply system having a processor and a memory, a program for that method, a computer-readable non-transitory recording medium storing the program, or a vehicle equipped with a power supply system, etc. [Industrial Applicability]

[0045] The power supply system of the present disclosure can be used in vehicles equipped with a high-voltage battery and an auxiliary battery. [Explanation of symbols]

[0046] 100 Power System 110 High-voltage battery 120 Auxiliary Battery 121 Battery 122 Microcomputer 123 Temperature Sensor 130 High-voltage DC / DC converter 140 B-DC 141 Microcomputer 142 SW 200 load

Claims

[Claim 1] A power supply system for controlling an auxiliary battery mounted on a vehicle, a first processing unit that monitors a discharge capacity of the auxiliary battery from a fully charged state; a second processing unit that determines whether the discharge capacity exceeds a threshold value that is determined based on a full charge capacity and a temperature of the auxiliary battery; a third processing unit that charges the auxiliary battery using a high-voltage battery mounted on the vehicle when the discharge capacity exceeds the threshold value; Power supply system.

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