Power supply system

Abstract

To provide a power supply system capable of appropriately determining a backup possibility in an auxiliary machine battery which is much affected by polarization.SOLUTION: A power supply system for controlling power supply to a load using a main machine battery and an auxiliary machine battery comprises: an acquisition section by which charge / discharge information of the auxiliary machine battery is acquired in predetermined timing and stored as a charge / discharge history; a correction section by which an internal resistance value of the auxiliary machine battery is corrected on the basis of the charge / discharge history; and a determination section for determining whether or not backup power feeding using the auxiliary battery can be performed in a case where the main machine battery falls based on the corrected internal resistance value of the auxiliary machine battery.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power supply system that controls power supply to a load using a main battery and an auxiliary battery. [Background technology]

[0002] Patent Document 1 discloses a power supply control device that includes a main power supply that supplies power to a load, and an auxiliary power supply that supplies backup power to the load when the main power supply fails. This power supply control device determines whether the auxiliary power supply is capable of outputting power required for backup processing to the load when the main power supply fails by passing a predetermined current from the auxiliary power supply to the load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-190470 A Summary of the Invention [Problem to be solved by the invention]

[0004] Rather than providing a dedicated auxiliary power source for backup processing of the main power source, it is conceivable to provide a backup function to an auxiliary battery whose main purpose is to supply power to an auxiliary load. However, the auxiliary battery is always subject to polarization, not only due to charging processing from the main battery (main power source), but also due to normal power supply processing to the auxiliary load and discharging processing (pumping processing) to the main battery in response to a drop in the power of the main battery. As such, since the auxiliary battery is more subject to polarization than a dedicated auxiliary power source, when the backup feasibility determination described in Patent Document 1 is performed, there is a risk that it will not be possible to appropriately determine whether the auxiliary battery can output the power required for backup.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a power supply system that can appropriately determine whether or not backup is possible for an auxiliary battery that is greatly affected by polarization. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the disclosed technology is a power supply system that controls power supply to a load using a main battery and an auxiliary battery, and includes an acquisition unit that acquires charge / discharge information of the auxiliary battery at a predetermined timing and accumulates it as a charge / discharge history, a correction unit that corrects the internal resistance value of the auxiliary battery based on the charge / discharge history, and a determination unit that determines whether or not backup power can be provided by the auxiliary battery in the event of a failure of the main battery based on the corrected internal resistance value of the auxiliary battery. Effect of the Invention

[0007] According to the power supply system of the present disclosure, it is possible to appropriately determine whether or not the auxiliary battery is capable of outputting the power required for backup, taking into account the effect of polarization associated with charging and discharging activities. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a functional block diagram of a power supply system and its peripheral parts according to an embodiment of the present disclosure. [Diagram 2] A flowchart illustrating a procedure for processing the charge / discharge history of the auxiliary battery executed by the control device. [Diagram 3] FIG. 13 is a diagram showing an example of a charge / discharge history of an auxiliary battery; [Figure 4] A flowchart illustrating a procedure for determining whether or not the auxiliary battery can be backed up, which is executed by the control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The power supply system of the present disclosure constantly acquires information on charging and discharging performed by the auxiliary battery, and accumulates this acquired information as a charging and discharging history (such as a histogram). The power supply system then corrects the discharge resistance value of the auxiliary battery based on the influence of polarization on the auxiliary battery estimated from the charging and discharging history, and appropriately determines whether or not backup power can be supplied by the auxiliary battery in the event of a failure of the main battery based on the corrected discharge resistance value. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [composition] Fig. 1 is a functional block diagram of a power supply system 1 and its peripheral parts according to an embodiment of the present disclosure. The functional blocks illustrated in Fig. 1 include a power supply system 1, a primary system load 110, and a secondary system load 120. The power supply system 1 includes a main battery 10, an auxiliary battery 20, a DC-DC converter 30, a switch 40, a first sensor 50, a second sensor 60, and a control device 70. In Fig. 1, power lines through which power is exchanged are indicated by solid lines, and signal lines through which control instructions and measured values ​​flow are indicated by dashed lines.

[0011] 1 can be mounted on vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs) that are equipped with functions (loads) that require a redundant power supply configuration, such as autonomous driving. The following description will be given taking as an example a case in which the power supply system 1 according to this embodiment is mounted on a vehicle.

[0012] The main battery 10 is a secondary battery configured to be chargeable and dischargeable, such as a lithium ion battery. The main battery 10 supplies its own stored electric power to a primary system load 110, a secondary system load 120, and the auxiliary battery 20 via a DC-DC converter 30 and a switch 40. The main battery 10 can also store electric power output by a generator (not shown) such as an alternator. In a vehicle, for example, a drive battery corresponds to the main battery 10.

[0013] The auxiliary battery 20 is a secondary battery configured to be chargeable and dischargeable, such as a lead-acid battery or a lithium-ion battery. The auxiliary battery 20 stores the power output from the main battery 10 via the DCDC converter 30, and supplies the power stored in the auxiliary battery 20 to the secondary system load 120 and the auxiliary load (not shown). The auxiliary battery 20 is provided with a function of performing a backup process to maintain (continue) the power supply to the secondary system load 120 in place of the main battery 10 when an abnormality occurs in the main battery 10 due to a power supply failure or the like. The power supply system 1 of this embodiment realizes a suitable determination of whether or not to perform the backup process, taking into account the influence of polarization occurring in the auxiliary battery 20.

[0014] The DCDC converter 30 is a voltage converter provided between the main battery 10 and the auxiliary battery 20, the primary load 110, and the secondary load 120, and converts the input voltage of the main battery 10 into a voltage required for the auxiliary battery 20, the primary load 110, and the secondary load 120, and outputs the voltage. For example, a step-down DCDC converter that steps down the voltage of the main battery 10 and outputs it to the auxiliary battery 20, the primary load 110, and the secondary load 120 can be used as the DCDC converter 30.

[0015] The primary load 110 is an in-vehicle device that operates on power supplied from the main battery 10. The primary load 110 includes important in-vehicle devices related to safe driving of the vehicle. Examples of important in-vehicle devices include devices and systems (brakes, steering, shift-by-wire, etc.) that must use a redundant power source to perform a so-called evacuation action in an emergency such as a main power supply failure in autonomous driving, in which the vehicle runs until it is stopped in a safe place.

[0016] The secondary load 120 is an in-vehicle device that operates with power supplied from the main battery 10 or the auxiliary battery 20 via the DCDC converter 30, with the main battery 10 as the main power source and the auxiliary battery 20 as the redundant power source. The secondary load 120 is provided with at least the same in-vehicle devices as the important in-vehicle devices related to the safe running of the vehicle provided in the primary load 110 in a redundant manner.

[0017] The switch 40 is inserted between the primary system load 110 and the secondary system load 120, and is configured to electrically connect or disconnect the primary system load 110 and the secondary system load 120 based on the control of the control device 70.

[0018] The first sensor 50 is a component for detecting the voltage output from the main battery 10 via the DC-DC converter 30, i.e., the voltage of the primary system, and is typically a voltage sensor. Information on the primary system voltage detected by this first sensor 50 is output to the control device 70.

[0019] The second sensor 60 is configured to detect the state of the auxiliary battery 20. The second sensor 60 includes a voltage sensor for detecting the voltage of the auxiliary battery 20, a current sensor for detecting the current of the auxiliary battery 20, and a temperature sensor for detecting the temperature of the auxiliary battery 20. Information on the state of the auxiliary battery 20 detected by the second sensor 60 is output to the control device 70.

[0020] The control device 70 is a device for determining whether the auxiliary battery 20 is in a state where it can back up the main battery 10 in an emergency, and for executing the backup process if possible. The control device 70 is configured to include an acquisition unit 71, a correction unit 72, and a determination unit 73.

[0021] The acquisition unit 71 acquires information related to the primary system voltage from the first sensor 50, and judges whether or not an abnormality such as a power loss (ground fault, etc.) has occurred in the primary system. This judgment can be made, for example, based on whether or not the detection value of the first sensor 50 is lower than a lower limit voltage value that appears in the primary system during normal times when no abnormality has occurred. The acquisition unit 71 also acquires information related to the state of the auxiliary battery 20 from the second sensor 60, acquires the charge / discharge state related to the charging and discharging actions performed in the auxiliary battery 20, and accumulates it as a charge / discharge history. This charge / discharge history will be described later.

[0022] The correction unit 72 calculates an influence degree indicating an influence of the charge / discharge process on the auxiliary battery 20 based on the charge / discharge history of the auxiliary battery 20 accumulated by the acquisition unit 71. Then, the correction unit 72 calculates a correction value based on the calculated influence degree, and corrects the internal resistance value (discharge resistance value) of the auxiliary battery 20 related to the discharge using this correction value. The internal resistance value can be derived using various well-known methods, such as determining a slope from a combination of the voltage value and current value of the auxiliary battery 20. The influence degree and the correction value will be described later.

[0023] The determination unit 73 determines whether the auxiliary battery 20 is in a state capable of outputting a predetermined backup power to the secondary system load 120 when the main battery 10 fails. This determination is made based on the internal resistance value (discharge resistance value) of the auxiliary battery 20 after being corrected by the correction unit 72.

[0024] A part or the whole of this control device 70 may be configured as an electronic control unit (ECU) that typically includes a processor such as a microcomputer, a memory, an input / output interface, etc. This electronic control unit can realize a part or the whole of the functions performed by each of the components of the acquisition unit 71, the correction unit 72, and the determination unit 73 described above by having the processor read and execute a program stored in the memory.

[0025] [control] Next, the control performed by the power supply system 1 according to this embodiment will be described with further reference to Figures 2, 3, and 4. In this embodiment, the control device 70 of the power supply system 1 performs charge / discharge history processing and backup feasibility determination processing.

[0026] [Charge / discharge history processing] 2 is a flowchart illustrating the procedure of the charge / discharge history processing of the auxiliary battery 20 executed by the control device 70. The charge / discharge history processing of the auxiliary battery 20 illustrated in FIG. 2 is repeatedly executed at a predetermined timing such as a fixed cycle (periodic processing including the start of the vehicle IG-OFF).

[0027] (Step S201) The acquisition unit 71 determines whether or not it is time to acquire information about the state of the auxiliary battery 20 from the second sensor 60. This timing can be set arbitrarily to a fixed period (e.g., several hundred milliseconds). If the acquisition unit 71 determines that it is time to acquire information (step S201, Yes), the process proceeds to step S202.

[0028] (Step S202) The acquisition unit 71 acquires information about the state of the auxiliary battery 20 from the second sensor 60, and accumulates charging and discharging actions performed on the auxiliary battery 20 as a charging and discharging history. An example of the charging and discharging history of the auxiliary battery 20 is shown in FIG.

[0029] The charge / discharge history illustrated in Fig. 3 is frequency information of charge / discharge in the form of a histogram in which the number of times that charging / discharging actions have occurred is classified by current amount, with the discharge current flowing out of the auxiliary battery 20 being a plus sign and the charge current flowing into the auxiliary battery 20 being a minus sign. For example, Fig. 3 shows that the number of times that a current of 5 amperes or more and less than 10 amperes has been discharged from the auxiliary battery 20 is more than 100 times and less than 1000 times, and the number of times that a current of 10 amperes or more and less than 20 amperes has been charged to the auxiliary battery 20 is more than 10 times and less than 100 times. In this charge / discharge history, if the current (absolute value) flowing due to charging / discharging action is small, it is determined that the influence of polarization in the auxiliary battery 20 is small, and if the current (absolute value) flowing due to charging / discharging action is large, it is determined that the influence of polarization in the auxiliary battery 20 is large.

[0030] When the acquisition unit 71 accumulates the charge / discharge history of the auxiliary battery 20, the process proceeds to step S203.

[0031] (Step S203) The determination unit 73 determines whether or not a backup feasibility determination has been performed for the auxiliary battery 20. The backup feasibility determination uses the charge / discharge history of the auxiliary battery 20 that has been accumulated from the time when the previous backup feasibility determination was performed until the time when the current backup feasibility determination is performed. Therefore, this determination is performed to determine whether or not the charge / discharge history accumulated up to that point is unnecessary.

[0032] If the determination unit 73 determines that the backup capability determination of the auxiliary battery 20 has already been performed (step S203, Yes), the process proceeds to step S205. On the other hand, if the determination unit 73 determines that the backup capability determination of the auxiliary battery 20 has not yet been performed (step S203, No), the process proceeds to step S204.

[0033] (Step S204) The determination unit 73 determines whether the auxiliary battery 20 has been disconnected from the primary system load 110 and the secondary system load 120 for a predetermined period of time. The disconnected state includes a state in which the auxiliary battery 20 is not in a state in which it can perform a power supply function, and a state in which the terminals of the auxiliary battery 20 are physically disconnected. If the auxiliary battery 20 is not functioning, the charge / discharge history of the auxiliary battery 20 is not necessary, and therefore this determination is made.

[0034] When the determination unit 73 determines that the auxiliary battery 20 has been disconnected from the primary system load 110 and the secondary system load 120 for a predetermined continuous time (step S204, Yes), the process proceeds to step S205. On the other hand, when the determination unit 73 determines that the auxiliary battery 20 has not been disconnected from the primary system load 110 and the secondary system load 120 for a predetermined continuous time (step S204, No), the process proceeds to step S201.

[0035] (Step S205) The determination unit 73 clears (deletes) the accumulated charge / discharge history of the auxiliary battery 20. This frees up the memory area for storing the charge / discharge history, eliminating the need to prepare a large memory area for storing all of the vast amount of past charge / discharge history. When the charge / discharge history of the auxiliary battery 20 is cleared by the determination unit 73, the process proceeds to step S201.

[0036] [Backup availability determination process] Fig. 4 is a flowchart illustrating the procedure of a backup possibility determination process for the auxiliary battery 20 executed by the control device 70. The backup possibility determination process for the auxiliary battery 20 illustrated in Fig. 4 is started, for example, when the vehicle is in an ignition-on state (IG-ON).

[0037] (Step S401) The correction unit 72 calculates the degree of influence of the auxiliary battery 20 based on the charge / discharge history of the auxiliary battery 20 accumulated by the acquisition unit 71 in the charge / discharge history processing. This degree of influence is a score that quantitatively represents the influence of polarization caused by the charge / discharge processing on the auxiliary battery 20. As an example of a method of calculating the score, in the case of the charge / discharge history shown in FIG. 3, the median value of each charge / discharge current category is set as a score, and the category score is increased in proportion to the number of charges / discharges performed in that category, and the total score of the entire charge / discharge history is calculated as the degree of influence. Note that this score calculation method is merely an example, and scores can be calculated using various other methods. When the degree of influence of the auxiliary battery 20 is calculated by the correction unit 72, the process proceeds to step S402.

[0038] (Step S402) The correction unit 72 determines whether the degree of influence of the auxiliary battery 20 is less than a first threshold value. This determination is made in order to determine whether the auxiliary battery 20 is affected by polarization. Therefore, the first threshold value is set to a value equal to or less than the minimum degree of influence (score) calculated from the charge / discharge history in which a charge / discharge action that is estimated to be affected by polarization on the auxiliary battery 20 has been performed.

[0039] If the correction unit 72 determines that the influence of the auxiliary battery 20 is less than the first threshold (step S402, Yes), the process proceeds to step S404. On the other hand, if the correction unit 72 determines that the influence of the auxiliary battery 20 is equal to or greater than the first threshold (step S402, No), the process proceeds to step S403.

[0040] (Step S403) The correction unit 72 judges whether the degree of influence of the auxiliary battery 20 is less than the second threshold value. This judgment is made to judge whether the influence of the polarization occurring in the auxiliary battery 20 is so large that it is impossible to determine whether backup is possible. Therefore, the second threshold value is set to a value equal to or greater than the maximum degree of influence (score) calculated from the charge / discharge history in which a charge / discharge action estimated to be capable of dealing with the influence of the polarization on the auxiliary battery 20 (capable of determining whether backup is possible) has been performed. The second threshold value is set to be greater than the first threshold value.

[0041] If the correction unit 72 determines that the influence of the auxiliary battery 20 is less than the second threshold (step S403, Yes), the process proceeds to step S405. On the other hand, if the correction unit 72 determines that the influence of the auxiliary battery 20 is equal to or greater than the second threshold (step S403, No), the process proceeds to step S408.

[0042] (Step S404) The correction unit 72 sets the correction value to "0 (zero)." This correction value is a value (resistance value) for correcting the internal resistance value of the auxiliary battery 20 obtained from the actual value detected by the second sensor 60. When the correction value is set to "0" by the correction unit 72, the process proceeds to step S406.

[0043] (Step S405) The correction unit 72 sets the correction value to "X (integer or rational number)". This correction value=X can be derived, for example, by using a map that associates the influence degree with the correction value. In the auxiliary battery 20, charging polarization occurs due to the charging process, and discharging polarization occurs due to the discharging process. For this reason, for the influence degree (negative sign) indicating that the discharging action is more frequent than the charging action, it is necessary to estimate the internal resistance value (discharge resistance value) to be smaller than the actual measured value according to the degree of influence, and for the influence degree (positive sign) indicating that the charging action is more frequent than the discharging action, it is necessary to estimate the internal resistance value (discharge resistance value) to be larger than the actual measured value according to the degree of influence. Therefore, it is desirable that the correspondence map between the influence degree and the correction value is set in advance so that the internal resistance value can be corrected to a value that takes into account the influence of the polarization of the auxiliary battery 20. When the correction value is set to "X" by the correction unit 72, the process proceeds to step S406.

[0044] (Step S406) Correction unit 72 corrects the internal resistance value of auxiliary battery 20 using the correction value (0 or X) set in step S404 or S405 above. The correction is performed by adding (or subtracting) the correction value to the internal resistance value that can be derived from the state of auxiliary battery 20 actually measured by second sensor 60. This correction causes the influence of polarization due to charging and discharging activities to be reflected in the internal resistance value of auxiliary battery 20. Once correction unit 72 has corrected the internal resistance value of auxiliary battery 20 using the correction value, the process proceeds to step S407.

[0045] (Step S407) The determination unit 73 performs a "backup feasibility determination" based on the corrected internal resistance value (discharge resistance value) of the auxiliary battery 20 to determine whether the auxiliary battery 20 is in a state in which it is capable of outputting a predetermined backup power to the secondary system load 120. A well-known method can be used for this backup feasibility determination. When the determination unit 73 performs the backup feasibility determination, the backup feasibility determination process for the auxiliary battery 20 ends.

[0046] (Step S408) The determination unit 73 determines that the auxiliary battery 20 is not in a state in which it can output a predetermined backup power to the secondary system load 120 (backup is not possible). When the determination unit 73 determines that backup is not possible, the backup possibility determination process for the auxiliary battery 20 is terminated.

[0047] <Actions and Effects> According to the power supply system 1 according to the embodiment of the present disclosure described above, charge / discharge information of the auxiliary battery 20 acquired at a predetermined timing is accumulated as a charge / discharge history, and the internal resistance value of the auxiliary battery 20 is corrected based on this charge / discharge history. In this correction process, the degree of influence of polarization caused by the charge / discharge process on the auxiliary battery 20 is calculated based on the charge / discharge history, and the internal resistance value of the auxiliary battery 20 is corrected using a correction value calculated based on this influence. This process makes it possible to appropriately determine whether the auxiliary battery 20 is capable of outputting power required for backup, taking into account the influence of polarization of the auxiliary battery 20 due to charging and discharging actions.

[0048] Furthermore, according to the power supply system 1 of this embodiment, by storing the charge / discharge history of the auxiliary battery 20 in a histogram format, it is no longer necessary to store detailed data detected by the second sensor 60 as is, and it is possible to save the memory area for storing the charge / discharge history. Furthermore, in the power supply system 1 of this embodiment, unnecessary charge / discharge history is cleared to free up the memory area, eliminating the need to prepare a large memory area.

[0049] Although one embodiment of the present disclosure has been described above, the present disclosure can be understood not only as the power supply system described above, but also as a method executed by a power supply system (control device) having a processor and 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]

[0050] The power supply system of the present disclosure can be used in vehicles equipped with a main battery and an auxiliary battery. [Explanation of symbols]

[0051] 1 Power System 10 Main engine battery 20 Auxiliary battery 30 DC-DC converter 40 Switch 50 First Sensor 60 Second Sensor 70 Control device 71 Acquisition Department 72 Correction section 73 Judgment section 110 Primary system load 120 Secondary system load

Claims

1. A power supply system that controls power supply to a load using a main battery and an auxiliary battery, an acquisition unit that acquires charge / discharge information of the auxiliary battery at a predetermined timing and accumulates the information as a charge / discharge history; a correction unit that corrects an internal resistance value of the auxiliary battery based on the charge / discharge history; and a determination unit that determines whether or not backup power supply by the auxiliary battery is possible when the main battery fails, based on the corrected internal resistance value of the auxiliary battery. Power supply system.

2. The charge / discharge history is charge / discharge frequency information obtained by classifying the number of times the auxiliary battery has been charged / discharged by each current amount. The power supply system of claim 1 .

3. The correction unit calculates an influence degree indicating an influence of the charging / discharging process on the auxiliary battery based on the frequency information, calculates a correction value based on the influence degree, and corrects an internal resistance value of the auxiliary battery using the correction value. The power supply system of claim 2 .

4. The acquisition unit erases the charge / discharge history when a state in which the auxiliary battery is not connected to the load continues for a predetermined time. The power supply system of claim 1 .

5. The determination unit determines that backup power supply by the auxiliary battery is impossible when the degree of influence estimated by the correction unit is equal to or greater than a predetermined value. The power supply system of claim 3.

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