Power supply device for vehicle

Abstract

To simplify a configuration of a power supply device for a vehicle capable of estimating deterioration.SOLUTION: A power supply device 1 includes: a charging unit 21 that charges a backup power supply 10; a discharging unit 23 that discharges the backup power supply 10; a charging voltage setting unit 34 that updates and sets a target charging voltage in accordance with a change in a charging environment including an environmental temperature; a charge / discharge control unit 35 that controls the charging unit 21 or the discharging unit 23 so that a charging voltage of the backup power supply 10 becomes the target charging voltage; a timing unit 36 that measures a charging maintenance time being a period during which the same target charging voltage continues to be set according to the charging environment from one update timing to the next update timing; a deterioration rate setting unit 37 that sets a deterioration rate α on the basis of the charging environment corresponding to the charging maintenance time; and a deterioration estimation unit 38 that estimates whether or not the backup power supply 10 has deteriorated on the basis of the charging maintenance time and the deterioration rate α.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a vehicle power supply device installed in a vehicle as an auxiliary power supply, in which the backup power supply is formed by multiple capacitors. To predict the lifespan of the auxiliary power supply, the vehicle power supply device constantly measures the internal resistance and internal capacitance of the capacitors during charging, and estimates the lifespan based on the measurement results. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-028908 Summary of the Invention [Problem to be solved by the invention]

[0004] The vehicle power supply device requires a measurement circuit for measuring the internal resistance and capacitance, which makes the configuration complicated.

[0005] An object of the present invention is to simplify the configuration of a vehicle power supply device that is capable of estimating deterioration. [Means for solving the problem]

[0006] One aspect of the present invention provides a vehicle power supply device including: a backup power supply; a charging unit that charges the backup power supply with power supplied from a main power supply; a discharging unit that discharges the backup power supply; a temperature detection unit that detects ambient temperature; a charging voltage setting unit that repeatedly updates and sets a target charging voltage at each update period in accordance with changes in a charging environment including the ambient temperature; a charge / discharge control unit that controls the charging unit or the discharging unit so that the charging voltage of the backup power supply becomes the target charging voltage; a timing unit that measures a charging maintenance time, which is a period during which the same target charging voltage is continuously set in accordance with the charging environment between two adjacent update periods, or a period during which the charging voltage is maintained at the target charging voltage within that period; a deterioration rate setting unit that sets a deterioration rate of the backup power supply based on the charging environment corresponding to the charging maintenance time; and a deterioration estimation unit that estimates whether the backup power supply has deteriorated based on the charging maintenance time and the deterioration rate.

[0007] According to the above configuration, deterioration is estimated based on the ambient temperature and charging voltage. Therefore, there is no need for a measurement circuit to measure special electrical characteristics related to the backup power supply, such as internal resistance or internal capacitance, which simplifies the configuration. [Effects of the Invention]

[0008] According to the present invention, it is possible to simplify the configuration of a vehicle power supply device capable of estimating deterioration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a power supply device according to an embodiment. [Figure 2] FIG. [Figure 3] Graph showing classification of charging environments. [Figure 4] 4 is a flowchart illustrating a control method executed by the power supply device. [Figure 5] Flowchart continued from Figure 4. [Figure 6] FIG. 6 is a diagram corresponding to FIG. 5 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0011] Referring to FIG. 1, the power supply device 1 according to the embodiment is a power supply device for a vehicle, and has an input terminal 11 connected to a main power supply 2, an output terminal 12 connected to a motor 4 of an in-vehicle electric device 3, and a communication terminal 13 connected to an external ECU 5.

[0012] The main power supply 2 is, for example, a DC 12V lead-acid battery mounted on the vehicle. Examples of the on-vehicle electric devices 3 include an electric door latch device, an electric tailgate, an electric sliding door, an electric fuel lid, an electric side mirror, and a power window. The external ECU 5 is mounted on the vehicle and has a CPU, memory, and input / output interface for information processing and communication.

[0013] The main power supply 2 stores the power required to operate the vehicle and functions as a power source for the on-board electric device 3 and the external ECU 5. Normally, the main power supply 2 supplies power to the motor 4, which operates the on-board electric device 3. The vehicle's ignition switch 6 is connected to a power supply line connecting the main power supply 2 to the external ECU 5. When the ignition switch 6 is in an off state, opening the power supply line, power supply from the main power supply 2 to the external ECU 5 is stopped. When the ignition switch 6 is in an on state, closing the power supply line, power is supplied from the main power supply 2 to the external ECU 5, making it operable. The external ECU 5 acquires or generates information indicating the vehicle state and outputs part of that information to the power supply device 1. An example of the information output from the external ECU 5 to the power supply device 1 is ignition information indicating the state (on or off) of the ignition switch 6.

[0014] The power supply device 1 is equipped with a chargeable and dischargeable backup power supply 10. The backup power supply 10 is configured, for example, with one or more capacitors. The charging voltage of the backup power supply 10 when fully charged is, for example, DC 5V to 6V. If an abnormality occurs in the main power supply 2 or its surroundings, the power supply device 1 supplies power from the backup power supply 10 to the motor 4. This allows the in-vehicle electric device 3 to operate even in the event of an abnormality. Abnormalities include, for example, a dead battery in the main power supply 2, a broken wire between the main power supply 2 and the motor 4, a vehicle collision, etc.

[0015] In addition to the backup power supply 10, the power supply device 1 includes a charging unit 21, a boosting unit 22, a discharging unit 23, a regulator 24, a temperature detecting unit 25, and a controller 30.

[0016] Charging unit 21 is located on input line 14 connecting input terminal 11 to backup power supply 10. Charging unit 21 switches between a state in which backup power supply 10 is charged by power supplied from main power supply 2 and a state in which power supply from main power supply 2 to backup power supply 10 is cut off. Boosting unit 22 is located on output line 15 connecting backup power supply 10 to output terminal 12. Boosting unit 22 boosts the voltage supplied from backup power supply 10 to a voltage (e.g., DC 10 V) required to drive motor 4. Boosting unit 22 is implemented by a boost circuit using an inductor, a switch, etc.

[0017] 1, input line 14 and output line 15 are shared on the side of backup power supply 10. In other words, input line 14 and output line 15 are interconnected via node 16, input terminal 11 is connected to output terminal 12 via input line 14, node 16, and output line 15, and node 16 is connected to backup power supply 10 via the shared portion of input line 14 and output line 15. Charging unit 21 is provided between input terminal 11 and node 16, and boosting unit 22 is provided between node 16 and output terminal 12.

[0018] Discharge unit 23 is connected to backup power supply 10 via wiring that is independent of both input line 14 and output line 15. Discharge unit 23 is implemented by an equalization circuit that uses resistors, switches, etc., and discharges backup power supply 10. This discharge is performed intentionally to prevent backup power supply 10 from being fully charged or overcharged, thereby delaying deterioration of backup power supply 10.

[0019] The controller 30 includes, for example, a central processing unit (CPU) or a micro processing unit (MPU) that cooperates with software to realize predetermined functions. The controller 30 may be configured with hardware circuits such as dedicated electronic circuits or reconfigurable electronic circuits designed to realize predetermined functions, or may be configured with various semiconductor integrated circuits. Examples of various semiconductor integrated circuits include, in addition to CPUs and MPUs, microcomputers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), and application specific integrated circuits (ASICs). The controller 30 may also include storage devices such as random access memory (RAM) and read only memory (ROM).

[0020] The controller 30 can operate using the main power supply 2 as a power source. In this regard, the controller 30 is connected to the input line 14 between the input terminal 11 and the charging unit 21 via a control power supply line 17. A regulator 24 is interposed in the control power supply line 17 and reduces the power supplied from the main power supply 2 to a voltage (e.g., 5 V) that ensures stable operation of the controller 30. The controller 30 is supplied with the reduced power.

[0021] The controller 30 controls the operations of the charging unit 21, the boosting unit 22, and the discharging unit 23. Through the control of these operations, the charging voltage of the backup power supply 10 is controlled, and the operation of the motor 4 is controlled. The operation control of the motor 4 is performed when an abnormality occurs, while the charging voltage control is performed at all times.

[0022] Referring to FIG. 2, the controller 30 includes a memory unit 31, an acquisition unit 32, a charge voltage measurement unit 33, a charge voltage setting unit 34, a charge / discharge control unit 35, a timing unit 36, a deterioration rate setting unit 37, a deterioration estimation unit 38, and an output unit 39.

[0023] The storage unit 31 is realized by the above-mentioned storage device. The storage unit 31 temporarily or permanently stores a program for controlling the charging voltage, a program for estimating the deterioration of the backup power supply 10, and information used to execute these programs.

[0024] The acquisition unit 32 acquires temperature information indicating the environmental temperature detected by the temperature detection unit 25 and ignition information output from the external ECU 5.

[0025] The temperature detection unit 25 is configured, for example, by a thermistor, and is disposed near the backup power supply 10. It is connected to the controller 30 and outputs temperature information to the controller 30. The temperature detection unit 25 detects, for example, the ambient air temperature around the backup power supply 10 or the surface temperature of the backup power supply 10 as the environmental temperature. The acquisition unit 32 sequentially acquires the temperature information at a predetermined cycle. Ignition information is input to the controller 30 via the communication terminal 13 and the communication line 18. If the ignition switch 6 is in the on state, the external ECU 5 outputs an on signal (for example, 5 V) indicating that the ignition switch 6 is in the on state. If the ignition switch 6 is in the off state, it may output an off signal indicating that the ignition switch 6 is in the off state, or the signal output may be stopped.

[0026] The charging voltage measuring unit 33 measures the charging voltage of the backup power supply 10. The controller 30 is connected to the common part of the input line 14 and the output line 15 via a voltage detection line 19. The charging voltage of the backup power supply 10 is input to the controller 30 via this common part and the voltage detection line 19. The charging voltage measuring unit 33 has a voltage dividing circuit that divides the input voltage, and measures the charging voltage based on the divided voltage value. Such a charging voltage measuring unit 33 has conventionally been generally provided in a power supply device 1 equipped with a backup power supply 10.

[0027] The charging voltage setting unit 34 determines the charging environment based on the temperature information and ignition information acquired by the acquisition unit 32. The charging voltage setting unit 34 sets a target charging voltage according to the determined charging environment. When the charging environment changes, the charging voltage setting unit 34 resets or updates the target charging voltage.

[0028] 3, the charging environment is determined based on which of a plurality of predetermined temperature categories the environmental temperature belongs to and the state of the ignition switch 6. In this embodiment, as an example, five temperature categories are set, and the state of the ignition switch 6 is either on or off. The charging voltage setting unit 34 determines which of the 10 (5 x 2) categories the charging environment belongs to based on the temperature information and the ignition information.

[0029] For example, the first temperature category is a temperature range of around 80°C. The second temperature category is a temperature range of around 60°C. The third temperature category is a temperature range of around 25°C. The fourth temperature category is a temperature range of around -20°C. The fifth temperature category is a temperature range of around -40°C. However, this is merely an example, and the number of temperature categories and the temperature ranges in each temperature category are not particularly limited.

[0030] The storage unit 31 stores in advance a table that defines the correspondence between each classification of the charging environment and the corresponding target charging voltage. The charging voltage setting unit 34 refers to the table and sets the target charging voltage based on the result of the determination of the charging environment.

[0031] The charging voltage setting unit 34 successively determines the charging environment based on the temperature information and ignition information successively acquired by the acquisition unit 32. Even if the environmental temperature fluctuates slightly, the determination result as to which classification the charging environment belongs is unlikely to change. If the environmental temperature changes significantly or the state of the ignition switch 6 is changed, the classification to which the charging environment belongs changes. In response to such changes in the charging environment, the charging voltage setting unit 34 resets or updates the target charging voltage based on the new determination result.

[0032] The charging environment is classified into 10 categories, and the same target charging voltage is set for some categories. For example, when the ignition switch 6 is off, the target charging voltage is 1.6 V regardless of the temperature category of the environmental temperature. Therefore, if the environmental temperature fluctuates significantly while the ignition switch 6 is off, the charging environment determination result will change, but the target charging voltage value itself will not change before and after the change in the determination result.

[0033] In this document, the term "update time" refers to the time when the charging voltage setting unit 34 determines that the charging environment has changed and resets the target charging voltage. It does not matter whether the target charging voltage value itself has changed at the update time. The charging voltage setting unit 34 repeats this update setting of the target charging voltage at each update time.

[0034] From one update time to the next, that is, in the period between two adjacent update times, the charging environment determination result remains the same, and therefore the target charging voltage is also maintained at the same value.

[0035] Returning to Fig. 2, the charge / discharge control unit 35 controls the charge unit 21 or the discharge unit 23 so that the charge voltage of the backup power supply 10 becomes the target charge voltage set by the charge voltage setting unit 34. If the charge voltage is less than the target charge voltage, the charge / discharge control unit 35 activates the charge unit 21 to increase the charge voltage so that it becomes the target charge voltage. If the charge voltage exceeds the target charge voltage, the charge / discharge control unit 35 activates the discharge unit 23 to decrease the charge voltage so that it becomes the target charge voltage.

[0036] The timer 36 measures the charge maintenance time. In this embodiment, the charge maintenance time is the period from one update time to the next update time, in other words, the period between two adjacent update times. Every time an update time arrives, the timer 36 ends measurement of the charge maintenance time from the previous update time to the present, and starts measurement of the charge maintenance time from the present to the next update time.

[0037] The deterioration estimation unit 38 estimates whether or not the backup power supply 10 has deteriorated. If it is determined that the backup power supply 10 has deteriorated, the output unit 39 outputs deterioration information indicating this to the outside of the controller 30. For example, the deterioration information is output to the external ECU 5. The external ECU 5 may execute a process of displaying a warning on the instrument panel of the vehicle in response to the input of the deterioration information.

[0038] The deterioration estimation unit 38 estimates whether the amount of capacity deterioration of the backup power supply 10 has reached a predetermined value (for example, -30%) without measuring the capacity of the power supply device 1, and thereby estimates the deterioration of the backup power supply 10.

[0039] The mechanism for estimating the deterioration according to the amount of capacity deterioration without actually measuring the capacity will be described below.

[0040] Before the power supply device 1 is mounted on a vehicle, a charging test is performed in which the amount of capacity degradation is measured constantly or at regular intervals from a state in which the amount of capacity degradation is zero, while maintaining a predetermined charging environment (particularly the ambient temperature) and maintaining the charging voltage at a predetermined value, and charging of the backup power supply 10 is continued. This makes it possible to identify the degradation arrival time required for the amount of capacity degradation to go from zero to a predetermined value. The charging test may be performed until the amount of capacity degradation (ΔC) actually reaches the predetermined value, and the degradation arrival time may be identified from the charging test. The charging test may be terminated before the amount of capacity degradation reaches the predetermined value, and an approximation curve may be fitted to the time change in the amount of capacity degradation during the charging test, and the degradation arrival time may be identified from this approximation curve.

[0041] Assume that a charging test is performed under certain reference conditions and a certain degradation time is identified. The reference conditions are set to relatively severe conditions, such as an ambient temperature of 65°C and a target charging voltage of 3.0V. In this case, the degradation time may be approximately 6,200 hours.

[0042] When power supply device 1 is mounted on a vehicle and the charging environment remains the same as the reference conditions, it can be assumed that the capacity degradation of backup power supply 10 has reached a predetermined value when the charge maintenance time reaches the degradation reaching time. However, in reality, it is impossible for charge / discharge control to be performed continuously for such a long period of time as 6,200 hours under such harsh conditions while mounted on a vehicle.

[0043] If the conditions change to lower the ambient temperature, the degradation time will be longer. If the conditions change to lower the target charging voltage, the degradation time will be longer.

[0044] For example, suppose a charging test is performed under conditions of an ambient temperature of 25°C and a target charging voltage of 2.8V, and the charging test period reaches 6200 hours. At this point, the amount of capacity degradation has not yet decreased to a predetermined value. The degradation time under these conditions is longer than 6200 hours, or in other words, a value obtained by multiplying 6200 hours by a multiplier value exceeding 1 (e.g., 32). Conversely, the degradation time under the standard conditions is shorter than the degradation time under conditions of an ambient temperature of 25°C and a target charging voltage of 2.8V, or in other words, a value obtained by multiplying the degradation time by the reciprocal of the multiplier value (e.g., 0.03).

[0045] Then, when charge / discharge control is performed in a vehicle under conditions of an ambient temperature of 25°C and a target charge voltage of 2.8V, the measured charge maintenance time can be converted to the charge maintenance time under the reference conditions by multiplying the measured charge maintenance time by the reciprocal of the multiplication factor. The reciprocal of the multiplication factor can be considered a conversion coefficient for converting the charge maintenance time under conditions other than the reference conditions to the charge maintenance time under the reference conditions. For example, if the actual charge maintenance time is 10 hours and the conversion factor is 0.03, the 10 hours can be converted to 0.3 hours (18 minutes) as the charge maintenance time under the reference conditions.

[0046] In the power supply device 1 according to this embodiment, the deterioration rate setting unit 37 sets a deterioration rate α for each update period in accordance with the charging environment corresponding to the charge maintenance time measured at that update period (the period between that update period and the previous update period). The deterioration rate α is a numerical value expressed in dimensionless units and corresponds to the conversion factor in the above description.

[0047] The deterioration rate α may be set in advance for each classification of the charging environment. In this case, a table defining the correspondence between each classification of the charging environment and the corresponding deterioration rate α is stored in advance in the storage unit 31. The deterioration rate setting unit 37 refers to the table at each update time and sets the deterioration rate α based on the classification of the charging environment immediately before the update time.

[0048] The deterioration rate α may be calculated from the following formula (4) based on the following formulas (1) to (3) in accordance with the charging environment at each time when it should be set.

[0049]

number

[0050] where T k is the temperature coefficient, T R is the ambient temperature under reference conditions (e.g., 65°C), T a is the ambient temperature during the charge maintenance time. V k is the voltage coefficient, V R is the target charging voltage under reference conditions (e.g., 3.0 V), V c is the target charging voltage that was actually set during the charging maintenance time. K is an acceleration coefficient, which corresponds to the multiplication factor in the above explanation.

[0051] Environmental temperature T a The smaller the temperature coefficient T k The acceleration coefficient K increases, and the deterioration rate α decreases. c The smaller the voltage coefficient V kThe acceleration coefficient K increases, and the deterioration rate α decreases. If the ambient temperature and target charging voltage are in the standard condition, the temperature coefficient T k and voltage coefficient V k becomes 1, and the deterioration rate α becomes 1. The measured charge maintenance time is treated as it is as the charge maintenance time under the reference conditions. Even when the table is stored in advance in the storage unit 31, the deterioration rate α is set based on the above formulas (1) to (4).

[0052] The deterioration estimation unit 38 calculates a deterioration value for each update period by multiplying the charge maintenance time measured at that update period by the deterioration rate set by the deterioration rate setting unit 37. The deterioration value is a numerical value expressed in units of time, and corresponds to the charge maintenance time under the reference conditions described above. Calculation of the deterioration value corresponds to the process of converting the charge maintenance time measured under conditions other than the reference conditions into the charge maintenance time under the reference conditions.

[0053] The deterioration estimation unit 38 calculates the cumulative deterioration value by integrating the deterioration values ​​at each update period. The calculated cumulative deterioration value may be stored in the storage unit 31 of the controller 30, or in an external memory 40 communicably connected to the controller 30. When integrating the deterioration value, the deterioration estimation unit 38 reads out the stored cumulative deterioration value, updates the cumulative deterioration value by adding a newly calculated deterioration value to the read cumulative deterioration value, and stores the updated cumulative deterioration value in the storage unit 31 or the external memory 40. The cumulative deterioration value is also a numerical value expressed in units of time. The cumulative deterioration value corresponds to the total charging period under standard conditions, calculated from the total charging maintenance time from when the backup power supply 10 was new to the present.

[0054] The degradation estimation unit 38 compares this accumulated degradation value with a threshold value. The threshold value corresponds to the degradation arrival time (e.g., 6,200 hours) identified in the charging test under the reference conditions described above. In essence, in this comparison process, the degradation estimation unit 38 determines whether the total charging period under the reference conditions has reached the degradation arrival time obtained under the reference conditions; in other words, it determines whether the amount of capacity degradation of the backup power supply 10 has decreased to a predetermined value. If the accumulated degradation value is less than the threshold value, the degradation estimation unit 38 determines that the backup power supply 10 has not yet deteriorated. If the accumulated degradation value is equal to or greater than the threshold value, the degradation estimation unit 38 determines that the backup power supply 10 has deteriorated.

[0055] Although it overlaps with the above, a control method executed by the controller according to this embodiment will be described with reference to the flowcharts of Figures 4 and 5. The processing shown in Figures 4 and 5 is repeatedly executed at a predetermined cycle.

[0056] First, the acquisition unit 32 acquires temperature information and ignition information (steps S1 and S2), and the charge voltage measurement unit 33 measures the charge voltage (step S3). The charge / discharge control unit 35 controls the operation of the charge unit 21 or the discharge unit 23 so that the measured charge voltage becomes the currently set target charge voltage (step S4).

[0057] Next, the charging voltage setting unit 34 determines the charging environment based on the information acquired in steps S1 and S2 (step S5). If there is no change in the charging environment (S6: NO), the process ends. If the charging environment has changed (S6: YES), the charging voltage setting unit 34 resets the target charging voltage according to the changed charging environment (step S10).

[0058] When the update time arrives in this manner, the timer 36 ends measurement of the charge maintenance time since the previous update time (step S11). The deterioration rate setting unit 37 sets a deterioration rate based on the charging environment from the previous update time to the current update time and the target charging voltage that was set according to the charging environment (step S12). The deterioration estimation unit 38 calculates a deterioration value by multiplying the charge maintenance time measured in step S11 by the deterioration rate set in step S12 (step S13). The deterioration estimation unit 38 calculates a deterioration accumulation value using the deterioration value calculated in step S13 (step S14), and updates and stores the calculated deterioration accumulation value in the storage unit 31 or the external memory 40 (step S15).

[0059] The deterioration estimation unit 38 determines whether the updated cumulative deterioration value is equal to or greater than a threshold value (step S16). If the cumulative deterioration value is less than the threshold value (S16: NO), the deterioration estimation unit 38 determines that the backup power supply 10 has not yet deteriorated. The timing unit 36 ​​starts measuring the charge maintenance time from the current update time (step S17), and the process ends. If the cumulative deterioration value is equal to or greater than the threshold value (S16: YES), the deterioration estimation unit 38 estimates that the backup power supply 10 has deteriorated. Furthermore, the deterioration estimation unit 38 estimates that the amount of capacity deterioration of the backup power supply 10 has decreased to a predetermined value. The output unit 39 outputs the deterioration information to an external device, such as the external ECU 5 (step S18), and the process ends.

[0060] According to this embodiment, deterioration is estimated based on the ambient temperature and charging voltage. Therefore, there is no need for a measurement circuit to measure special electrical characteristics of the backup power supply 10, such as internal resistance or internal capacitance. This simplifies the configuration of the power supply device 1.

[0061] 6 shows a flowchart according to a modified example. The charge maintenance time does not necessarily have to be the period between two adjacent update periods, and the start of the charge maintenance time does not have to be the earlier of the two adjacent update periods. For example, when the target charge voltage is changed at an update period, a deviation occurs between the actual charge voltage and the target charge voltage at that time. The start of the charge maintenance time may be the time when this deviation is eliminated (see step S17A).

[0062] Although the embodiments have been described above, the above configurations can be modified as appropriate within the scope of the present invention. [Explanation of symbols]

[0063] 1 Power supply 2 Main power 3 In-vehicle electric equipment 4 motors 5 External ECU 6 Ignition switch 10 Backup power supply 11 Input terminal 12 Output terminal 13 Communication terminal 14 Input lines 15 Output line 16 nodes 17 Control power line 18 Communication lines 19 Voltage detection wire 21 Live parts 22 Booster section 23 Discharge section 24 Regulator 25 Temperature detection unit 30 Controller 31 Storage section 32 Acquisition Department 33 Charging voltage measurement section 34 Charging voltage setting section 35 Charge / discharge control unit 36 Timing section 37 Deterioration rate setting section 38 Deterioration estimation unit 39 Output section 40 External Memory α degradation rate

Claims

1. A backup power supply, a charging unit that charges the backup power supply with power supplied from a main power supply; a discharge unit that discharges the backup power supply; a temperature detection unit that detects an environmental temperature; a charging voltage setting unit that repeatedly updates and sets the target charging voltage at each update time in response to changes in the charging environment including the environmental temperature; a charge / discharge control unit that controls the charging unit or the discharging unit so that the charging voltage of the backup power supply becomes the target charging voltage; a timer that measures a charge maintenance time, which is a period during which the same target charge voltage is continuously set in accordance with the charging environment between two adjacent update times, or a period during which the charge voltage is maintained at the target charge voltage within the period; a deterioration rate setting unit that sets a deterioration rate of the backup power supply based on the charging environment corresponding to the charge maintenance time; a deterioration estimation unit that estimates whether the backup power supply has deteriorated based on the charge maintenance time and the deterioration rate; A vehicle power supply device comprising:

2. The deterioration estimation unit calculating a deterioration value by multiplying the charge maintenance time by the deterioration rate; estimating whether the backup power supply has deteriorated based on the deterioration value; The vehicle power supply device according to claim 1 .

3. The deterioration estimation unit calculating a cumulative deterioration value by integrating the deterioration values; When the cumulative deterioration value is equal to or greater than a predetermined threshold, it is estimated that the backup power supply has deteriorated. The vehicle power supply device according to claim 2 .

4. the deterioration rate setting unit sets the deterioration rate to a larger value as the environmental temperature and the target charging voltage increase. The vehicle power supply device according to any one of claims 1 to 3.

5. the charging voltage setting unit sets the target charging voltage to a smaller value as the environmental temperature increases; The vehicle power supply device according to any one of claims 1 to 3.

6. further comprising an acquisition unit that acquires information indicating whether an ignition switch of the vehicle is on or off; the charging voltage setting unit sets the target charging voltage in accordance with the state of the ignition switch. The vehicle power supply device according to any one of claims 1 to 3.

7. a charging voltage measuring unit for measuring the charging voltage of the backup power supply; the timing unit measures a period during which the measured charging voltage is maintained at the target charging voltage as the charging maintenance time. The vehicle power supply device according to any one of claims 1 to 3.

8. an acquisition unit that acquires ignition information indicating whether an ignition switch of the vehicle is on or off; The charging environment includes a state of the ignition switch. The vehicle power supply device according to any one of claims 1 to 3.

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