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 Art

[0002] Patent Document 1 discloses a power supply control device including a main power supply that supplies power to a load and an auxiliary power supply that backup-supplies power to the load when the main power supply fails. In this power supply control device, it is determined whether the auxiliary power supply can output the power necessary for backup processing to the load by flowing a predetermined current from the auxiliary power supply to the load.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Rather than providing a dedicated auxiliary power supply for backup processing of the main power supply, it is conceivable to give the auxiliary battery, which is mainly used to supply power to the auxiliary load, a backup function. However, the auxiliary battery is always affected by polarization, not only in the charging process from the main battery (main power supply), but also in the normal power supply process to the auxiliary load and the discharging process (pumping process) to the main battery due to the power reduction of the main battery. Thus, since the auxiliary battery is more affected by polarization than a dedicated auxiliary power supply, there is a risk that it may not be possible to appropriately determine whether the auxiliary battery can output the power necessary for backup when performing the backup availability determination described in Patent Document 1.

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

[0006] To solve the above problems, one aspect of the disclosed technology is a power supply system for controlling the supply of power to a load using a main battery and an auxiliary battery, comprising: an acquisition unit that acquires charge and discharge information of the auxiliary battery at predetermined timings and stores it as a charge and discharge history; a correction unit that corrects the internal resistance value of the auxiliary battery based on the charge and discharge history; and a determination unit that determines whether 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. [Effects of the Invention]

[0007] According to the power supply system of the present disclosure described above, it is possible to appropriately determine whether or not the auxiliary battery is capable of outputting the power necessary for backup, taking into account the effects of polarization associated with charging and discharging. [Brief explanation of the drawing]

[0008] [Figure 1] Functional block diagram of a power supply system and its peripheral parts according to one embodiment of the present disclosure. [Figure 2] A flowchart illustrating the procedure for processing the charge and discharge history of the auxiliary battery, as performed by the control unit. [Figure 3] A diagram showing an example of the charge and discharge history of an auxiliary battery. [Figure 4] A flowchart illustrating the procedure for determining whether the auxiliary battery backup is possible, as performed by the control unit. [Modes for carrying out the invention]

[0009] The power supply system disclosed herein continuously acquires information on the charging and discharging of the auxiliary battery and stores this acquired information as a charge / discharge history (histogram, etc.). The power supply system then corrects the discharge resistance value of the auxiliary battery based on the effect of polarization on the auxiliary battery estimated from the charge / discharge history, and appropriately determines whether backup power supply by the auxiliary battery is possible in the event of a failure of the main battery based on the corrected discharge resistance value. The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0010] <Embodiment> [composition] Figure 1 is a functional block diagram of a power supply system 1 and its peripheral parts according to one embodiment of the present disclosure. The functional block illustrated in Figure 1 includes the 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 Figure 1, power lines through which power is exchanged are shown as solid lines, and signal lines through which control instructions and measured values ​​are carried are shown as dashed lines.

[0011] The configuration of the power supply system 1 shown in Figure 1 can be installed, as an example, in vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs) that implement functions (loads) requiring a redundant power supply configuration, such as autonomous driving. The following explanation will use the case in which the power supply system 1 according to this embodiment is installed in a vehicle as an example.

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

[0013] The auxiliary battery 20 is a rechargeable secondary battery, such as a lead-acid battery or a lithium-ion battery. The auxiliary battery 20 stores power output from the main battery 10 via the DC-DC converter 30 and supplies the power it has stored to the secondary system load 120 and auxiliary loads (not shown). The auxiliary battery 20 is equipped with a function to perform backup processing to maintain (continue) the power supply to the secondary system load 120 in place of the main battery 10 if an abnormality occurs in the main battery 10 due to power failure or the like. In the power supply system 1 of this embodiment, a suitable determination of whether or not backup processing is possible is realized, taking into account the effects of polarization occurring in the auxiliary battery 20.

[0014] The DC-DC converter 30 is installed between the main battery 10, the auxiliary battery 20, the primary system load 110, and the secondary system load 120. It is a voltage converter that converts the voltage of the main battery 10, which is input to the auxiliary battery 20, the primary system load 110, and the secondary system load 120 to the voltages required for output. For example, a step-down type DC-DC converter that steps down the voltage of the main battery 10 and outputs it to the auxiliary battery 20, the primary system load 110, and the secondary system load 120 can be used for this DC-DC converter 30.

[0015] The primary system load 110 consists of in-vehicle equipment powered by the main battery 10. This primary system load 110 includes important in-vehicle equipment related to the safe operation of the vehicle. Examples of important in-vehicle equipment include devices and systems (such as brakes, steering, and shift-by-wire) that must be powered by redundant power to perform so-called evasive maneuvers, such as driving the vehicle to a safe location in the event of an emergency such as a main power failure during autonomous driving.

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

[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 configured to detect the voltage output from the main battery 10 via the DCDC converter 30, that is, the voltage of the primary system, and is typically a voltage sensor. Information regarding 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. This 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, etc. Information regarding 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 that determines whether the auxiliary battery 20 is in a state where it can back up the main battery 10 in an emergency, and executes the backup process if possible. This control device 70 includes an acquisition unit 71, a correction unit 72, and a determination unit 73.

[0021] The acquisition unit 71 acquires information on the primary system voltage from the first sensor 50 and determines whether an abnormality such as a power loss (ground fault, etc.) has occurred in the primary system. This determination can be made based on whether the detected value of the first sensor 50 is lower than the lower limit voltage value that appears in the primary system during normal times when no abnormality has occurred, for example. Also, the acquisition unit 71 acquires information on the state of the auxiliary battery 20 from the second sensor 60, obtains the charge-discharge state regarding the charge and discharge actions performed on the auxiliary battery 20, and accumulates it as a charge-discharge history. The charge-discharge history will be described later.

[0022] The correction unit 72 calculates the degree of influence indicating the impact 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 degree of influence and uses this correction value to correct the internal resistance value (discharge resistance value) of the auxiliary battery 20 related to discharge. For the derivation of the internal resistance value, various well-known methods can be used, such as obtaining the slope from the combination of the voltage value and current value of the auxiliary battery 20. Note that the degree of influence and the correction value will be described later.

[0023] The determination unit 73 determines whether the auxiliary battery 20 is in a state where it can output 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] Part or all of this control device 70 can typically be configured as an electronic control unit (ECU: Electronic Control Unit) including a processor such as a microcomputer, a memory, and an input / output interface. By the processor reading and executing the program stored in the memory, part or all of the functions performed by the above-described acquisition unit 71, correction unit 72, and determination unit 73 can be realized.

[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] Figure 2 is a flowchart illustrating the procedure for processing the charge and discharge history of the auxiliary battery 20, which is performed by the control device 70. The charge and discharge history processing of the auxiliary battery 20, as illustrated in Figure 2, is repeatedly performed at predetermined timings, such as a fixed cycle (periodic processing including the vehicle's IG-OFF startup).

[0027] (Step S201) The acquisition unit 71 determines whether it is time to acquire information regarding the status of the auxiliary battery 20 from the second sensor 60. This timing can be arbitrarily set to a fixed period (for example, 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 regarding the status of the auxiliary battery 20 from the second sensor 60 and stores the charging and discharging activities performed on the auxiliary battery 20 as a charging and discharging history. Figure 3 shows an example of the charging and discharging history of the auxiliary battery 20.

[0029] The charge-discharge history illustrated in Figure 3 is a histogram of charge-discharge frequency information, where the number of times charge-discharge operations occurred is divided by current amount, with the discharge current flowing out of the auxiliary battery 20 being assigned a positive sign and the charge current flowing into the auxiliary battery 20 being assigned a negative sign. For example, Figure 3 shows that the number of times a current of 5 amperes or more and less than 10 amperes was discharged from the auxiliary battery 20 was 100 or more and less than 1000 times, and the number of times a current of 10 amperes or more and less than 20 amperes was charged into the auxiliary battery 20 was 10 or more and less than 100 times. In this charge-discharge history, if the current (absolute value) that flowed due to charge-discharge operations was small, it is judged that the effect of polarization in the auxiliary battery 20 was small, and if the current (absolute value) that flowed due to charge-discharge operations was large, it is judged that the effect of polarization in the auxiliary battery 20 was large.

[0030] Once the charge and discharge history of the auxiliary battery 20 is accumulated by the acquisition unit 71, the process proceeds to step S203.

[0031] (Step S203) The determination unit 73 determines whether or not a backup feasibility determination for the auxiliary battery 20 has already been performed. The backup feasibility determination uses the charge and discharge history of the auxiliary battery 20 accumulated from the time of the previous backup feasibility determination to the time of the current determination. Therefore, this determination is made to determine whether or not the charge and discharge history accumulated so far is unnecessary.

[0032] If the determination unit 73 determines that it has already performed a determination on whether the auxiliary battery 20 can be backed up (step S203, yes), the process proceeds to step S205. On the other hand, if the determination unit 73 determines that it has not yet performed a determination on whether the auxiliary battery 20 can be backed up (step S203, no), the process proceeds to step S204.

[0033] (Step S204) The determination unit 73 determines whether the auxiliary battery 20 has remained disconnected from the primary system load 110 and the secondary system load 120 for a predetermined period of time. Disconnection includes situations where the auxiliary battery 20 is not in a state to perform its power supply function, or where the terminals of the auxiliary battery 20 are physically disconnected. This determination is made because if the auxiliary battery 20 is not functioning, its charge and discharge history is unnecessary.

[0034] If 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 period of time (step S204, yes), the process proceeds to step S205. On the other hand, if the determination unit 73 determines that the auxiliary battery 20 has been connected to the primary system load 110 and the secondary system load 120 for a predetermined period of time (step S204, no), the process proceeds to step S201.

[0035] (Step S205) The determination unit 73 clears (erases) the accumulated charge and discharge history of the auxiliary battery 20. This frees up the memory area that stores the charge and discharge history, eliminating the need to prepare a large memory area to store all of the vast past charge and discharge history. Once the determination unit 73 clears the charge and discharge history of the auxiliary battery 20, the process proceeds to step S201.

[0036] [Backup feasibility determination process] Figure 4 is a flowchart illustrating the procedure for determining whether the auxiliary battery 20 can be backed up, as performed by the control device 70. The auxiliary battery 20 backup feasibility determination process illustrated in Figure 4 is initiated, for example, when the vehicle is turned on (IG-ON).

[0037] (Step S401) The correction unit 72 calculates the influence of the auxiliary battery 20 based on the charge and discharge history of the auxiliary battery 20 accumulated by the acquisition unit 71 during the charge and discharge history processing. This influence is a score that quantitatively represents the effect that polarization caused by the charge and discharge process has on the auxiliary battery 20. As an example of the score calculation method, using the charge and discharge history shown in Figure 3, the midpoint value of each charge and discharge current category is taken as the score, and the score of the category increases in proportion to the number of charge and discharge operations performed in that category, and the total score of the entire charge and discharge history is calculated as the influence. Note that this score calculation method is merely an example, and it is possible to calculate the score using various other methods. Once the 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 influence of the auxiliary battery 20 is less than a first threshold. This determination is made to determine whether or not polarization is affecting the auxiliary battery 20. Therefore, this first threshold is set to a value less than or equal to the minimum influence (score) calculated from the charge / discharge history in which charge / discharge operations that are estimated to have affected the auxiliary battery 20 by polarization have occurred.

[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 determines whether the influence of the auxiliary battery 20 is less than the second threshold. This determination is made to determine whether the effect of polarization occurring in the auxiliary battery 20 is so large that it is impossible to determine whether backup is possible. Therefore, this second threshold is set to a value greater than or equal to the maximum influence (score) calculated from the charge / discharge history in which charge / discharge operations that are estimated to be able to address the effect of polarization on the auxiliary battery 20 (i.e., whether backup is possible) are performed. The second threshold is set to be greater than the first threshold.

[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) used to correct the internal resistance value of the auxiliary battery 20, which is determined from the actual value detected by the second sensor 60. Once 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 (an integer or rational number)". This correction value = X can be derived, for example, using a map that associates the degree of influence with the correction value. In the auxiliary battery 20, charging polarization occurs during the charging process, and discharging polarization occurs during the discharging process. For this reason, for an influence degree (negative sign) indicating that discharging is more frequent than charging, the internal resistance value (discharge resistance value) must be estimated to be smaller than the measured value according to the degree of influence, and for an influence degree (positive sign) indicating that charging is more frequent than discharging, the internal resistance value (discharge resistance value) must be estimated to be larger than the measured value according to the degree of influence. Therefore, it is desirable that the correspondence map between the degree of influence and the correction value be pre-set so that the internal resistance value can be corrected to a value that takes into account the effect of polarization in 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) The correction unit 72 corrects the internal resistance value of the auxiliary battery 20 using the correction value (0 or X) set in step S404 or S405. The correction is performed by adding (or subtracting) the correction value to the internal resistance value that can be derived from the state of the auxiliary battery 20 measured by the second sensor 60. This correction reflects the effect of polarization due to charging and discharging in the internal resistance value of the auxiliary battery 20. Once the internal resistance value of the auxiliary battery 20 is corrected by the correction unit 72 using the correction value, the process proceeds to step S407.

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

[0046] (Step S408) The determination unit 73 determines that the auxiliary battery 20 is not in a state where 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 feasibility determination process for the auxiliary battery 20 is terminated.

[0047] <Effects and Actions> According to the power supply system 1 of one embodiment of the present disclosure described above, charge and discharge information of the auxiliary battery 20 acquired at predetermined timings is stored as a charge and discharge history, and the internal resistance value of the auxiliary battery 20 is corrected based on this charge and discharge history. In this correction process, the degree to which polarization generated during the charge and discharge process affects the auxiliary battery 20 is calculated based on the charge and discharge history, and the internal resistance value of the auxiliary battery 20 is corrected using a correction value calculated based on this degree of influence. Through this process, it is possible to appropriately determine whether the auxiliary battery 20 is capable of outputting the power necessary for backup, taking into account the effect of polarization of the auxiliary battery 20 due to the charging and discharging process.

[0048] Furthermore, according to the power supply system 1 of this embodiment, by storing the charge and discharge history of the auxiliary battery 20 in histogram format, it becomes unnecessary to store the detailed data detected by the second sensor 60 as is, thus saving the memory area used to store the charge and discharge history. Moreover, in the power supply system 1 of this embodiment, unnecessary charge and discharge history is cleared to free up memory area, eliminating the need to provide 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) equipped with a processor and memory, a program for that method, a computer-readable non-temporary recording medium storing that program, or a vehicle equipped with the power supply system. [Industrial applicability]

[0050] The power supply system disclosed herein can be used in vehicles equipped with a main battery and an auxiliary battery, etc. [Explanation of Symbols]

[0051] 1. Power System 10 Main unit battery 20 Auxiliary battery 30 DC-DC converters 40 switches 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 the supply of power to a load using a main battery and an auxiliary battery, An acquisition unit that acquires charge and discharge information of the auxiliary battery at a predetermined timing and stores it as a charge and discharge history, A correction unit corrects the internal resistance value of the auxiliary battery based on the charge and discharge history, The system includes a determination unit that determines whether backup power supply by the auxiliary battery is possible in the event of a failure of the main battery, based on the corrected internal resistance value of the auxiliary battery. The aforementioned charge / discharge history is charge / discharge frequency information, which is the number of charge / discharge cycles performed by the auxiliary battery, categorized by current amount. Power supply system.

2. The correction unit calculates the degree of influence of the charge / discharge process on the auxiliary battery based on the frequency information, calculates a correction value based on the degree of influence, and corrects the internal resistance value of the auxiliary battery using the correction value. The power supply system according to claim 1.

3. The determination unit determines that backup power supply by the auxiliary battery is impossible if the degree of influence estimated by the correction unit is greater than or equal to a predetermined value. The power supply system according to claim 2.

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