Backup power supply system and control method of backup power supply system

Abstract

A backup power supply system is provided with a first port, a second port, a charging circuit unit, an output circuit unit, a deterioration detection unit, and a control unit. The charging circuit unit charges the power storage unit with power input from the power supply via the first port. The output circuit unit supplies power from the power storage unit to the load via the second port in a power-off state in which the power supply is powered off. The deterioration detection unit detects a deterioration state of the power storage unit. The control unit controls, on the basis of the detection result of the deterioration detection unit, a set value of the charging voltage when the charging circuit unit charges the power storage unit.

Description

Technical Field

[0001] The present disclosure relates to a backup power supply system and a method for controlling the backup power supply system. More specifically, the present disclosure relates to a backup power supply system that supplies power from a power storage unit to a load in a power outage state in which power is cut off and a method for controlling the backup power supply system. Background Art

[0002] Patent Document 1 discloses a vehicle power supply device including a power backup unit using a capacitor unit formed of a plurality of capacitors. This vehicle power supply device supplies power from the power backup unit to the vehicle's electronic control unit when a battery in the vehicle malfunctions.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-322987 Summary of the Invention

[0006] When the capacitor forming the capacitor cell (electricity storage unit) deteriorates, the internal resistance of the capacitor increases and the capacitance (capacity) of the capacitor decreases, thereby reducing the amount of electricity that can be stored in the capacitor cell.

[0007] A backup power supply system according to one embodiment of the present disclosure includes a first port, a second port, a charging circuit unit, an output circuit unit, a degradation detection unit, and a control unit. The first port is connectable to a power source. The second port is connectable to a load. The charging circuit unit uses the power input from the power source via the first port to charge the storage unit so that the voltage of the storage unit, i.e., the charging voltage, reaches a set value. In a power-off state where the power source is cut off, the output circuit unit supplies power from the storage unit to the load via the second port. The degradation detection unit detects the degradation state of the storage unit. The control unit controls the set value of the charging voltage when the charging circuit unit charges the storage unit based on the detection result of the degradation detection unit.

[0008] A control method for a backup power supply system according to one embodiment of the present disclosure is a control method for a backup power supply system having a first port, a second port, a charging circuit unit, and an output circuit unit, and includes a degradation detection process and a control process. The backup power supply system comprises a first port, a second port, a charging circuit unit, and an output circuit unit. The first port is connectable to a power supply. The second port is connectable to a load. The charging circuit unit uses the power input from the power supply via the first port to charge the storage unit so that the voltage of the storage unit, i.e., the charging voltage, reaches a set value. In a power-off state where the power supply is turned off, the output circuit unit supplies power from the storage unit to the load via the second port. In the degradation detection process, the degradation state of the storage unit is detected. In the control process, the set value of the charging voltage when the charging circuit unit charges the storage unit is controlled based on the detection result of the degradation state of the storage unit.

[0009] According to the present disclosure, it is possible to provide a backup power supply system and a method for controlling the backup power supply system that can extend the life of a power storage unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic circuit block diagram of a backup power supply system according to one embodiment of the present disclosure.

[0011] Figure 2 This is a graph showing the relationship between the cumulative usage time and the capacitance of the power storage unit included in the backup power supply system.

[0012] Figure 3 This is a graph showing the relationship between the cumulative usage time and the internal resistance of the power storage unit included in the backup power supply system.

[0013] Figure 4 This is a graph showing the relationship between the cumulative usage time of the power storage unit and the set value of the charging voltage in the backup power supply system.

[0014] Figure 5 This is a graph showing the relationship between the cumulative usage time and the capacitance of the storage unit in the backup power supply system.

[0015] Figure 6 Flowchart illustrating the operation of the backup power supply system.

[0016] Figure 7 Flowchart illustrating the operation of the backup power supply system.

[0017] Figure 8 This is a graph showing temporal changes in the power supplied to the load and the terminal voltage of the power storage unit when power is supplied from the power storage unit to the load in the initial stage of use of the power storage unit.

[0018] Figure 9 This is a graph showing temporal changes in the terminal voltage of the power storage unit when power is supplied from the power storage unit to the load in an end-of-life state where the cumulative usage time of the power storage unit exceeds the life time.

[0019] Figure 10 This is a graph showing the relationship between the cumulative usage time of the power storage unit and the setting value of the charging voltage in the backup power supply system according to Modification 1. DETAILED DESCRIPTION

[0020] The following describes in detail the backup power supply system and the control method for the backup power supply system according to the embodiments with reference to the accompanying drawings. The configuration described in the following embodiments is merely an example of the present disclosure. The present disclosure is not limited to the following embodiments; various modifications may be made based on design, etc., as long as the effects of the present disclosure are achieved.

[0021] (Implementation Method)

[0022] (1) Summary

[0023] Figure 1 This is a schematic circuit block diagram of the backup power supply system 1 according to the present embodiment.

[0024] The backup power supply system 1 includes a first port P1 , a second port P2 , a charging circuit unit 11 , an output circuit unit 12 , a degradation detection unit 21 , and a control unit 22 .

[0025] The first port P1 can be connected to a power source 2 .

[0026] The second port P2 can be connected to a load 3 .

[0027] The charging circuit unit 11 charges the power storage unit 10 using the electric power input from the power supply 2 via the first port P1 so that the voltage of the power storage unit 10 , ie, the charging voltage, reaches a set value.

[0028] In the power-off state where the power source 2 is turned off, the output circuit unit 12 supplies electric power from the power storage unit 10 to the load 3 via the second port P2 .

[0029] Degradation detection unit 21 detects a degradation state of power storage unit 10 .

[0030] The control unit 22 controls the setting value of the charging voltage when the charging circuit unit 11 charges the power storage unit 10 based on the detection result of the degradation detection unit 21 .

[0031] Here, the first port P1 is connected to the power source 2 via the wire 32, and the second port P2 is connected to the load 3 via the wire 33. The first port P1 and the second port P2 may be components (terminals) for connecting the wires 32 and 33, etc., or may be, for example, leads of electronic components or portions of conductive materials formed as wiring on a circuit board. Furthermore, "connecting" two elements means electrically connecting the two elements; other elements may exist between the two elements.

[0032] Figure 2 This is a graph showing the relationship between the cumulative usage time and the capacitance of the storage unit 10. A1, A2, and A3 in the graph respectively represent the time variation of the capacitance when the setting value of the charging voltage is set to V1, V2, and V3 (V1 < V2 < V3). In addition, the cumulative usage time is the time elapsed from the initial use of the storage unit 10, when the cumulative usage time of the storage unit 10 is zero and is set as the initial use. The cumulative usage time may also include the time when the storage unit 10 is not storing electricity. In addition, Figure 3 This is a graph showing the relationship between the cumulative usage time of the power storage unit 10 and the internal resistance (e.g., DC resistance). B1, B2, and B3 in the graph respectively represent the time variation of the internal resistance when the setting value of the charging voltage is set to V1, V2, and V3 (V1 < V2 < V3). Figure 2 and Figure 3 As can be seen, as the cumulative usage time of power storage unit 10 increases, the degradation of power storage unit 10 becomes more severe, resulting in a decrease in the capacitance and an increase in the internal resistance of power storage unit 10. Furthermore, the higher the set charging voltage value, the greater the rate of decrease in capacitance and the rate of increase in internal resistance relative to the cumulative usage time. In other words, the higher the set charging voltage value, the faster the degradation of power storage unit 10.

[0033] In the backup power supply system of the comparative example, the charging voltage set value (target value) used by the charging circuit unit 11 when charging the power storage unit 10 is always set to a constant value, regardless of the degradation state of the power storage unit 10. In this case, to ensure that the power storage unit 10 can supply the required power (power required for the load 3 to perform a predetermined operation) to the load 3 even when the cumulative usage time reaches the end of its lifespan, the charging voltage set value must be based on the capacitance of the power storage unit 10 at the end of its lifespan. On the other hand, in the early stages of the use of the power storage unit 10, the capacitance of the power storage unit 10 is greater and the internal resistance is lower than at the end of its lifespan. Therefore, the charging voltage set value of the power storage unit 10 required to supply the required power to the load 3 at the initial capacitance is lower than the charging voltage set value based on the capacitance at the end of its lifespan. Therefore, if the charging voltage set value is based on the capacitance at the end of its lifespan, as in the backup power supply system of the comparative example, the power storage unit 10 will be charged at an unnecessarily high voltage during the early stages of use, potentially accelerating the degradation of the power storage unit 10. Note that the life time referred to here refers to the time from the start of use of power storage unit 10 until it becomes unable to supply power required for load 3 to perform a predetermined operation.

[0034] In contrast, in the backup power supply system 1 of the present embodiment, the control unit 22 controls the charging voltage set value used by the charging circuit unit 11 when charging the power storage unit 10 based on the detection results of the degradation detection unit 21. For example, the control unit 22 can control the charging voltage set value to a lower value than at the end of the life of the power storage unit 10 during its initial use, when the capacitance of the power storage unit 10 is greater and the internal resistance is lower than at the end of its life. As the charging voltage set value of the power storage unit 10 increases, the degradation of the power storage unit 10 becomes more severe. Therefore, by controlling the charging voltage set value to a lower value than at the end of its life during the initial use, the control unit 22 can suppress degradation of the power storage unit 10. Furthermore, by delaying the onset of degradation of the power storage unit 10, the life of the power storage unit 10 can be extended.

[0035] (2) Details

[0036] Below, refer to Figures 1 to 9 The backup power supply system 1 of this embodiment will be described in detail.

[0037] (2.1) Structure

[0038] The backup power supply system 1 of this embodiment is assumed to be mounted on a vehicle 100 such as an automobile (see Figure 1 The vehicle 100 is equipped with a power source 2 and a load 3. In addition, the backup power supply system 1 is mounted on the vehicle 100 and supplies power to the load 3 provided in the vehicle 100.

[0039] The power source 2 connected to the first port P1 via the electric wire 32 is, for example, a battery of the vehicle 100 .

[0040] Load 3, connected to second port P2 via electrical wire 33, is an electrical device mounted on vehicle 100. Load 3 may be, for example, an electric brake system, a shift-by-wire system, or a control system that controls the electric brake system, shift-by-wire system, or an advanced driver-assistance system (ADAS). Load 3 is not limited to a single electrical device and may include multiple electrical devices.

[0041] Backup power supply system 1 supplies power from power storage unit 10 to load 3 when power supply 2 of vehicle 100 (e.g., a car battery) is disconnected. Thus, even when power supply 2 is disconnected, load 3 can operate by supplying power from power storage unit 10. Furthermore, in a non-disconnected state when power supply 2 is not disconnected, power is supplied from power supply 2 to load 3 via, for example, a power supply circuit 34 provided external to backup power supply system 1.

[0042] Here, the power-off state of the power supply 2 refers to a state in which the voltage Vin input from the power supply 2 to the first port P1 is reduced to less than a prescribed reference voltage due to a fault in the power supply 2, grounding of the power supply 2 or the wire 32 connecting the power supply 2 and the first port P1, etc. The non-power-off state of the power supply 2 refers to a state in which the voltage Vin input from the power supply 2 to the first port P1 is greater than the reference voltage. The reference voltage is preferably set to a voltage that is lower than the rated voltage of the power supply 2 and higher than the minimum operating voltage (also referred to as the minimum guaranteed voltage) required for the normal operation of the load 3. In addition, the minimum operating voltage of the load 3 refers to the lower limit value of the operating voltage required for the operation of the load 3, or a voltage obtained by adding a prescribed margin voltage to the lower limit value of the operating voltage.

[0043] As described above, the backup power supply system 1 includes the first port P1, the second port P2, the charging circuit unit 11, and the output circuit unit 12. Furthermore, the backup power supply system 1 includes the processing unit 20 having the functions of the aforementioned degradation detection unit 21 and control unit 22. Furthermore, the backup power supply system 1 includes the third port P3, the power failure detection unit 13, the discharge circuit unit 14, and the communication circuit unit 15.

[0044] The power storage unit 10 includes, for example, a plurality of power storage cells connected in series or in parallel. Each of the plurality of power storage cells includes, for example, an electric double layer capacitor (EDLC) capable of rapid charge and discharge. In other words, the power storage unit 10 includes an electric double layer capacitor.

[0045] The charging circuit unit 11 includes, for example, a semiconductor switching element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) connected between the first port P1 and the power storage unit 10. The semiconductor switching element has its on / off state or on-resistance controlled by a drive signal input from the control unit 22. Alternatively, the charging circuit unit 11 may further include a drive circuit that controls the on / off state of the semiconductor switching element in response to the drive signal input from the control unit 22. The charging circuit unit 11 controls the current value flowing through the semiconductor switching element to the power storage unit 10 by varying the on / off state or on-resistance of the semiconductor switching element in response to the drive signal input from the control unit 22. This allows the charging circuit unit 11 to charge the power storage unit 10 using the power input from the power supply 2 via the first port P1, thereby controlling the charge level and terminal voltage VB of the power storage unit 10. The terminal voltage VB of power storage unit 10 refers to the voltage at the output terminal of power storage unit 10. The value of terminal voltage VB varies depending on the charging and discharging of power storage unit 10. The set value of the charging voltage is the set value (target value) set by charging circuit unit 11 when charging power storage unit 10. It is the value of terminal voltage VB when charging is complete. Charging circuit unit 11 is configured to charge power storage unit 10 so that the voltage of power storage unit 10, i.e., the charging voltage, reaches the set value.

[0046] The power failure detection unit 13 detects the voltage value of the voltage Vin input from the power supply 2 to the first port P1 and compares the voltage value of the voltage Vin with a reference voltage. If the voltage value of the voltage Vin is greater than the reference voltage, the power failure detection unit 13 outputs a detection signal to the processing unit 20 indicating that the power supply 2 is not disconnected. If the voltage value of the voltage Vin is less than the reference voltage, the power failure detection unit 13 outputs a detection signal to the processing unit 20 indicating that the power supply 2 is disconnected.

[0047] The output circuit unit 12 includes, for example, a semiconductor switching element, such as a MOSFET, connected between the power storage unit 10 and the second port P2. The semiconductor switching element is controlled to be turned on or off based on a drive signal input from the control unit 22. Alternatively, the output circuit unit 12 may further include a drive circuit that controls the on / off state of the semiconductor switching element based on the drive signal input from the control unit 22. By turning on the semiconductor switching element based on the drive signal input from the control unit 22, the output circuit unit 12 can supply power from the power storage unit 10 to the load 3 via the output circuit unit 12 and the second port P2.

[0048] Upon receiving a discharge command from the control unit 22, the discharge circuit unit 14 discharges the charge stored in the power storage unit 10. For example, the discharge circuit unit 14 includes a series circuit comprising a switch and a discharge resistor connected in parallel with the power storage unit 10. Upon receiving a discharge command from the processing unit 20, for example, the discharge circuit unit 14 turns on the switch and discharges the charge stored in the power storage unit 10 via the discharge resistor.

[0049] The third port P3 is connected to a communication line 35 that connects, for example, an ECU (Electronic Control Unit) 4 of the vehicle 100 and the communication circuit unit 15 .

[0050] The communication circuit unit 15 includes, for example, a communication module compliant with a communication standard such as the CAN standard or the LIN standard used in an in-vehicle network, and communicates with the ECU 4 of the vehicle 100 .

[0051] The processing unit 20 is comprised, for example, of a microcomputer equipped with a processor and memory. Specifically, the processing unit 20 is implemented by a computer system equipped with a processor and memory. Furthermore, the computer system functions as the processing unit 20 by executing an appropriate program on the processor. The program may be pre-recorded in memory, provided via a telecommunications link such as the internet, or recorded on a non-transitory recording medium such as a memory card. Furthermore, the processing unit 20 is not limited to being implemented by a computer system; it may also be implemented by analog circuits, gate drive circuits, and the like.

[0052] Processing unit 20 has the functions of the aforementioned degradation detection unit 21 and control unit 22. Processing unit 20 also has the function of notification unit 23. Furthermore, degradation detection unit 21, control unit 22, and notification unit 23 merely represent functions implemented by processing unit 20 and do not necessarily represent actual structures.

[0053] Degradation detection unit 21 detects the degradation state of power storage unit 10. In backup power supply system 1, when vehicle 100 is no longer in use (for example, when the ignition key is switched from START to OFF), processing unit 20 outputs a discharge command to discharge circuit unit 14, causing the charge stored in power storage unit 10 to be discharged. When vehicle 100 is used again, charging circuit unit 11 charges power storage unit 10. Degradation detection unit 21 uses current sensor 16 to detect the current value of current I1 flowing from charging circuit unit 11 to power storage unit 10 while charging, and obtains terminal voltage VB of power storage unit 10 from power storage unit 10. Degradation detection unit 21 calculates the internal resistance (DC resistance) of power storage unit 10 based on the current value of current I1 flowing from charging circuit unit 11 to power storage unit 10 and terminal voltage VB of power storage unit 10, for example. Furthermore, degradation detection unit 21 calculates the capacitance of power storage unit 10 by calculating the cumulative value (i.e., the amount of charge) of current I1 flowing through power storage unit 10 until terminal voltage VB of power storage unit 10 reaches a predetermined voltage value. Degradation detection unit 21 then detects the degradation state of power storage unit 10 (the degree of degradation at that time) based on the capacitance and internal resistance of power storage unit 10. While degradation detection unit 21 detects the degradation state of power storage unit 10 by detecting the internal resistance and capacitance of power storage unit 10, the method for detecting the degradation state may be modified as appropriate.

[0054] Based on the detection result of the degradation state of power storage unit 10 by degradation detection unit 21, control unit 22 controls the set value (target value) of the charging voltage used by charging circuit unit 11 when charging power storage unit 10. As degradation of power storage unit 10 becomes more severe, the capacitance of power storage unit 10 decreases and the internal resistance of power storage unit 10 increases. Therefore, based on the detection result of degradation detection unit 21, control unit 22 controls the set value of the charging voltage to a higher voltage as degradation of power storage unit 10 becomes more severe.

[0055] Furthermore, based on the detection result of the degradation state of the power storage unit 10, the control unit 22 controls the set value of the charging voltage to the voltage value required to charge the power storage unit 10 to a specified storage capacity. The specified storage capacity refers to the storage capacity that can supply a voltage above the minimum operating voltage to the load 3 for a specified power supply time or longer in a power-off state. In other words, based on the detection result of the degradation detection unit 21, the control unit 22 controls the set value of the charging voltage (when the charging circuit unit 11 charges the power storage unit 10) to a voltage value that can supply the power required for the load 3 to perform the specified operation (required power). This allows the backup power supply system 1 to supply the power required for operation from the power storage unit 10 to the load 3 even when the power source 2 is off.

[0056] Figure 4This is a graph showing the relationship between the cumulative usage time of power storage unit 10 and the set value of the charging voltage. E1 in the graph represents the set value of the charging voltage when control unit 22 changes the set value of the charging voltage according to the degradation state of power storage unit 10. E2 in the graph represents the set value of the charging voltage when the set value of the charging voltage is set to a fixed value V10 regardless of the degradation state of power storage unit 10. Fixed value V10 is set based on the capacitance and internal resistance of power storage unit 10 when the cumulative usage time of power storage unit 10 reaches the end of its life, which is a predetermined life span, and is the required charging voltage value required for power storage unit 10 to supply the required power to load 3.

[0057] like Figure 2 and Figure 3 As shown, in the initial use of the storage unit 10, the capacitance of the storage unit 10 is larger and the internal resistance is smaller than when the storage unit 10 is used for a long time. Therefore, in the initial use of the storage unit 10, the set value of the charging voltage can be set to a set value V11 that is smaller than the fixed value V10. If the degradation of the storage unit 10 becomes more serious as the cumulative use time of the storage unit 10 increases, the control unit 22 gradually increases the set value of the charging voltage according to the increase in the cumulative use time. Here, Figure 4 In the figure, time t3 represents the life of the storage unit 10 when the set value of the charging voltage is set to a fixed value V10. In contrast, the backup power supply system 1 of this embodiment sets the set value of the charging voltage to a voltage value lower than the fixed value V10 during the period T1 before time t1. Therefore, in this embodiment, compared with the case where the set value of the charging voltage is controlled to a constant value (fixed value V10), it is possible to delay the degradation of the storage unit 10 from becoming serious, and the life can be extended from t3 to t1. In addition, Figure 5 Graph showing the relationship between the cumulative usage time and the capacitance of power storage unit 10 . Figure 5 F1 indicates that the setting value of the charging voltage is as follows Figure 4 The capacitance changes when the degradation state changes as shown in E1 in FIG. Figure 5 F2 means setting the charging voltage to Figure 4 The capacitance change when it is set to a fixed value V10 as in E2 in FIG.

[0058] like Figure 4 As shown, control unit 22 sets the charging voltage setting value at the initial stage of use to a setting value V11 that is lower than fixed value V10. As degradation of power storage unit 10 progresses, the charging voltage setting value is gradually increased. This delays the decrease in the capacitance of power storage unit 10 compared to a case where the charging voltage setting value is fixed at fixed value V10. Therefore, backup power supply system 1 of this embodiment can delay the onset of degradation of power storage unit 10.

[0059] Here, when the cumulative usage time of the power storage unit 10 reaches time t2, the set value of the charging voltage reaches the upper limit value V12 (see Figure 4 ), the control unit 22 maintains the set value of the charging voltage at the upper limit V12. Specifically, the control unit 22 controls the set value of the charging voltage to a voltage range below the upper limit V12. Here, the upper limit V12 of the charging voltage is set to a voltage value that is a predetermined margin voltage lower than the voltage value at which an abnormality such as valve opening or gas generation may occur in the EDLC constituting the power storage unit 10. If the set value of the charging voltage reaches the upper limit V12, the control unit 22 maintains the set value of the charging voltage at the upper limit V12. This prevents the power storage unit 10 from being charged to a voltage higher than the upper limit V12, thereby reducing the possibility of an abnormality in the power storage unit 10.

[0060] Here, when the set value of the charging voltage determined by the control unit 22 reaches the upper limit value V12, the notification unit 23 transmits a notification signal from the communication circuit unit 15 to the ECU 4 of the vehicle 100, notifying that the power storage unit 10 has reached the limit of its life. Based on the notification signal received from the backup power supply system 1, the ECU 4 can recognize that the power storage unit 10 has reached the limit of its life.

[0061] Furthermore, when the communication circuit unit 15 receives information from the ECU 4 indicating that the vehicle 100 has stopped, the control unit 22 determines the discharge amount of the power storage unit 10 based on the information and outputs a discharge command to the discharge circuit unit 14. In other words, upon receiving information indicating that the vehicle 100 is stopped, the control unit 22 outputs a discharge command to the discharge circuit unit 14. Upon receiving the discharge command, the discharge circuit unit 14 turns on a switch, allowing charge to flow from the power storage unit 10 through the switch to the discharge resistor, thereby discharging the power storage unit 10. Thus, when the communication circuit unit 15 receives information from the ECU 4 indicating that the vehicle 100 has stopped, the control unit 22 outputs a discharge command to the discharge circuit unit 14, causing the charge to be discharged from the power storage unit 10. When the vehicle 100 is stopped, the backup power supply system 1 does not need to supply power to the load 3. Therefore, the control unit 22 controls the discharge circuit unit 14 to reduce the terminal voltage VB of the power storage unit 10, thereby further delaying degradation of the power storage unit 10.

[0062] The stop information input from ECU 4 also includes information indicating the stop status of vehicle 100. The information indicating the stop status of vehicle 100 includes, for example, at least one of information indicating that the shift lever of vehicle 100 is in the park position, information indicating that the side brake of vehicle 100 is applied, and information indicating that the driving speed of vehicle 100 is zero. The time required for vehicle 100 to resume driving varies depending on the stop status of vehicle 100. Because power storage unit 100 must be charged to a set charging voltage value before vehicle 100 resumes driving, control unit 22 preferably controls the amount of discharge from power storage unit 10 so that the shorter the time to resume driving determined based on the stop information, the smaller the amount of discharge from power storage unit 10.

[0063] Furthermore, the control unit 22 may control the amount of discharge from the power storage unit 10 by the discharge circuit unit 14 based on the stop information and the degradation state of the power storage unit 10. In other words, the control unit 22 may determine the amount of discharge from the power storage unit 10 based on both the stop information and the degradation state of the power storage unit 10. After calculating the discharge amount based on the time to resume driving determined from the stop information, the control unit 22 adjusts the discharge amount calculated based on the stop information according to the degradation state of the power storage unit 10. For example, as degradation of the power storage unit 10 worsens, the capacitance of the power storage unit 10 decreases, shortening the time required to charge the power storage unit 10. Therefore, the control unit 22 may control the discharge amount of the power storage unit 10 to increase as degradation of the power storage unit 10 worsens. Thus, when the vehicle 100 is stopped, the control unit 22 controls the discharge circuit unit 14 to reduce the terminal voltage VB of the power storage unit 10, thereby further delaying degradation of the power storage unit 10.

[0064] (2.2) Action Description

[0065] The following is based on Figure 6 and Figure 7 The operation of the backup power supply system 1 according to this embodiment will be described below. Figure 6 and Figure 7 The flowchart shown is merely an example of the control method of the backup power supply system 1 according to the present embodiment, and the order of the processes may be changed as appropriate, and processes may be added or omitted as appropriate.

[0066] First, based on Figure 6 The flowchart of FIG. 1 illustrates the operation of charging the power storage unit 10 by the backup power supply system 1 .

[0067] When the ignition key of the vehicle 100 is turned on (step ST1 : YES), the backup power supply system 1 starts operating, and the control unit 22 controls the charging circuit unit 11 to start charging the power storage unit 10 (step ST2 ).

[0068] When current I1 flows from charging circuit unit 11 to power storage unit 10 and terminal voltage VB of power storage unit 10 gradually increases, degradation detection unit 21 calculates the internal resistance and capacitance of power storage unit 10 based on the detection results of current I1 and terminal voltage VB. Degradation detection unit 21 then detects the degradation state of power storage unit 10 based on the internal resistance and capacitance of power storage unit 10 (step ST3).

[0069] When degradation detection unit 21 detects a degradation state of power storage unit 10, control unit 22 determines a set value for the charging voltage of power storage unit 10 based on the detection result of the degradation state of power storage unit 10 (step ST4). Here, control unit 22 determines the set value for the charging voltage based on the degradation state of power storage unit 10 to be a voltage value that enables power storage unit 10 to store enough power to supply the required power to load 3.

[0070] After determining the set value of the charging voltage, the control unit 22 controls the charging circuit unit 11 to charge the power storage unit 10 so that the terminal voltage VB of the power storage unit 10 reaches the set value determined in step ST4 (step ST5).

[0071] While continuing to charge the power storage unit 10 , the control unit 22 monitors whether or not a power failure of the power supply 2 has occurred based on the detection signal input from the power failure detection unit 13 (step ST6 ).

[0072] Here, when the power supply 2 is not in the power-off state (step ST6 : NO), the control unit 22 returns to step ST5 and continues charging the power storage unit 10 .

[0073] On the other hand, when the power supply 2 is powered off (step ST6: yes), the control unit 22 controls the output circuit unit 12 to supply power from the power storage unit 10 to the load 3 (step ST7), thereby enabling the load 3 to operate even when the power supply 2 is powered off.

[0074] In the backup power supply system 1 of the present embodiment, when the vehicle 100 temporarily stops while the power storage unit 10 is being charged, an interruption process is executed to discharge the power storage unit 10. Figure 7 The flowchart illustrates the interrupt processing.

[0075] When vehicle 100 is temporarily stopped while power storage unit 10 is charged to the set charging voltage, and communication circuit unit 15 receives a stop message from ECU 4 of vehicle 100 (step ST11: YES), control unit 22 determines the amount of discharge from power storage unit 10 based on the stop message (step ST12). Control unit 22 then outputs a discharge command to discharge circuit unit 14, causing discharge circuit unit 14 to discharge the charge stored in power storage unit 10 (step ST13).

[0076] Here, when the amount of discharge from power storage unit 10 has not reached the amount of discharge determined in step ST12 (step ST14 : NO), control unit 22 controls discharge circuit unit 14 to continue discharging from power storage unit 10 .

[0077] On the other hand, if the amount discharged from power storage unit 10 reaches the amount discharged determined in step ST12 (step ST14: YES), control unit 22 causes discharge circuit unit 14 to stop discharging from power storage unit 10 (step ST15). Subsequently, upon receiving a release notification of the stop information from ECU 4 (step ST16), control unit 22 controls charging circuit unit 11 to charge power storage unit 10 (step ST17), charging power storage unit 10 to the set charging voltage determined in step ST4 before vehicle 100 begins traveling.

[0078] If the stop information is not received in step ST11 (step ST11 : NO), the control unit 22 ends the interruption process.

[0079] Here, Figure 8 The graph shows the time variation of the power supplied to the load 3 and the terminal voltage VB of the power storage unit 10 when the power supply is cut off at the initial stage of use of the power storage unit 10 and the power is supplied from the power storage unit 10 to the load 3. Figure 8 G1 in FIG. 1 represents a waveform when the set value of the charging voltage is set to a set value V21 corresponding to the degradation state of the power storage unit 10 . Figure 8 G2 in FIG. 5 represents a waveform when the set value of the charging voltage is set to a fixed value V10.

[0080] When power supply 2 loses power at time t10 and backup power supply system 1 begins supplying power to load 3, load 3's power consumption is high from time t10, when load 3 begins operating, to time t11. However, starting at time t11, power consumption decreases. Consequently, at time t10, the current flowing to load 3 increases sharply, causing the terminal voltage VB of power storage unit 10 to drop sharply from its initial set value V21 at time t10 to voltage V22, and then gradually decrease from time t11. Then, at time t11, the power supplied to load 3 decreases sharply, causing the terminal voltage VB of power storage unit 10 to recover from voltage V23 to voltage V24, and then gradually decrease from voltage V24. Furthermore, during the power supply time T10 from time t10 to time t12, the terminal voltage VB of power storage unit 10 remains above the minimum operating voltage Vmin of load 3, allowing the power required for operation to be supplied from power storage unit 10 to load 3.

[0081] Here, if the set value for the charging voltage of power storage unit 10 is set to a fixed value V10, power storage unit 10 is charged to a fixed value V10 that is higher than the set value V21 determined based on the degradation state of power storage unit 10. Therefore, at time t12, after a predetermined power supply time T10 has elapsed from time t10, terminal voltage VB of power storage unit 10 also increases by difference dV1. Thus, when the set value for the charging voltage of power storage unit 10 is set to a fixed value V10, during a period when degradation of power storage unit 10 is less severe than at the end of its life (e.g., during initial use), the charging voltage set value is set to an unnecessarily high voltage compared to a case where the charging voltage set value is determined based on the degradation state of power storage unit 10. In contrast, in the present embodiment, the control unit 22 determines the set value of the charging voltage based on the degradation state of the storage unit 10. Therefore, compared with the case where the set value of the charging voltage is set to a fixed value V10, the terminal voltage VB of the storage unit 10 can be lowered, the degradation of the storage unit 10 can be suppressed, and the degradation of the storage unit 10 can be delayed from becoming serious.

[0082] in addition, Figure 9 The graph shows the time variation of the terminal voltage VB of the storage unit 10 when the power supply 2 is disconnected and power is supplied from the storage unit 10 to the load 3 in the end-of-life state where the cumulative usage time of the storage unit 10 exceeds the life time. Figure 9 H1 in FIG. 1 represents a temporal change in terminal voltage VB when the set value of the charging voltage is set to a set value V21A corresponding to the degradation state of power storage unit 10 . Figure 9 H2 in FIG. 1 represents a temporal change in the terminal voltage VB when the set value of the charging voltage is set to a fixed value V10 .

[0083] When the charging voltage is set to a constant fixed value V10, in the end-of-life state where the cumulative usage time exceeds the life time, at time t23 after a predetermined power supply time T10 has elapsed from time t21 when power supply from power storage unit 10 to load 3 was started, the terminal voltage VB of power storage unit 10 falls below the minimum operating voltage Vmin, and thus the required power cannot be supplied to load 3.

[0084] In contrast, in this embodiment, control unit 22 determines the set value of the charging voltage based on the degradation state of power storage unit 10. In the end-of-life state, the set value of the charging voltage is set to a set value V21A that is higher than the fixed value V10. This allows the terminal voltage VB of power storage unit 10 to be maintained at a voltage higher than the minimum operating voltage Vmin even at time t23, which is the time of power supply time T10 after time t21. In other words, by determining the set value of the charging voltage based on the degradation state of power storage unit 10, control unit 22 can supply the required power required for load 3 to operate from power storage unit 10. Thus, by setting the set value of the charging voltage higher than the fixed value V10, control unit 22 can extend the life of power storage unit 10 and ensure its usability, compared to a case where the set value of the charging voltage is set to a constant fixed value V10.

[0085] Furthermore, when control unit 22 sets a set value for the charging voltage based on the degradation state of power storage unit 10, and if the set value for the charging voltage reaches upper limit value V12, control unit 22 limits the set value for the charging voltage to upper limit value V12. At this time, notification unit 23 transmits a notification signal from communication circuit 15 to ECU 4 of vehicle 100 notifying ECU 4 of the reaching of the life limit of power storage unit 10, thereby enabling ECU 4 of vehicle 100 to recognize that power storage unit 10 has reached its life limit.

[0086] (3) Modification

[0087] The above embodiment is only one of the various embodiments of the present disclosure. As long as the purpose of the present disclosure can be achieved, the above embodiment can be modified in various ways according to the design, etc. In addition, the same function as that of the backup power supply system 1 can also be achieved by a control method of the backup power supply system 1, a computer program, or a non-temporary recording medium having a program recorded thereon. A control method of a backup power supply system 1 in one embodiment is a control method of a backup power supply system 1 having a first port P1, a second port P2, a charging circuit unit 11, and an output circuit unit 12, and includes degradation detection processing and control processing. The first port P1 can be connected to the power supply 2. The second port P2 can be connected to the load 3. The charging circuit unit 11 uses the power input from the power supply 2 via the first port P1 to charge the storage unit 10. In the power-off state where the power supply 2 is off, the output circuit unit 12 supplies power from the storage unit 10 to the load 3 via the second port P2. The degradation state of the storage unit 10 is detected in the degradation detection process. In the control process, the setting value of the charging voltage when charging circuit unit 11 charges storage unit 10 is controlled based on the detection result of the degradation state of storage unit 10. One embodiment of the (computer) program is a program for causing a computer system to execute the control method of backup power supply system 1.

[0088] The following lists variations of the above embodiment. The variations described below can be combined and applied as appropriate. Hereinafter, the backup power supply system 1 of the above embodiment may also be referred to as a basic structure.

[0089] The backup power supply system 1 in the present disclosure includes a computer system. The computer system is mainly composed of a processor and a memory as hardware. The functions of the backup power supply system 1 in the present disclosure are realized by the processor executing the program recorded in the memory of the computer system. The program can be pre-recorded in the memory of the computer system, or provided through an electrical communication line, or recorded in a non-temporary recording medium such as a memory card, an optical disk, a hard disk drive, etc. that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits such as IC or LSI mentioned here are called differently according to the degree of integration, including integrated circuits called system LSI, VLSI (Very Large Scale Integration) or ULSI (Ultra Large Scale Integration). In addition, an FPGA (Field-Programmable Gate Array) programmed after the LSI is manufactured, or a logic device that can reconfigure the connection relationship within the LSI or reconfigure the circuit division within the LSI can also be used as a processor. Multiple electronic circuits can be integrated into one chip or distributed on multiple chips. Multiple chips can be integrated into a single device or distributed across multiple devices. The computer system described herein includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also comprised of one or more electronic circuits including semiconductor integrated circuits or large-scale integrated circuits.

[0090] (3.1) Modification 1

[0091] In the basic configuration, control unit 22 continuously changes the set value of the charging voltage based on the result of detection of the degradation state of power storage unit 10 by degradation detection unit 21 . However, the set value of the charging voltage may be changed in stages. Figure 10 Graph showing the relationship between the cumulative usage time of power storage unit 10 and the set value of the charging voltage.

[0092] Degradation detection unit 21 compares the degradation level, calculated based on the internal resistance and capacitance of power storage unit 10, with a predetermined threshold value. The degradation level indicates the severity of degradation, with a higher level indicating more severe degradation. For example, if the degradation level of power storage unit 10 is below the threshold value before the cumulative usage time of power storage unit 10 reaches time t3, degradation detection unit 21 determines that the degradation level of power storage unit 10 is in the first degradation stage. If the cumulative usage time of power storage unit 10 exceeds time t3, the degradation level of power storage unit 10 exceeds the threshold value, and degradation detection unit 21 determines that the degradation level of power storage unit 10 is in the second degradation stage.

[0093] Then, based on the detection result of degradation detection unit 21, control unit 22 sets the charging voltage setting value to V31 when the degradation state of power storage unit 10 is at the first degradation stage, and sets the charging voltage setting value to V32 when the degradation state of power storage unit 10 is at the second degradation stage (V31 < V32). In other words, when the degradation state of power storage unit 10 includes the first degradation stage, where the degradation level is below a predetermined threshold, and the second degradation stage, where the degradation level exceeds the threshold, control unit 22 controls charging voltage setting value V32 for the second degradation stage to a higher voltage value than charging voltage setting value V31 for the first degradation stage.

[0094] In this way, control unit 22 sets charging voltage setting value V31 in the first degradation stage to be lower than charging voltage setting value V32 in the second degradation stage. This can suppress degradation of power storage unit 10 and delay further degradation of power storage unit 10. Furthermore, control unit 22 gradually changes the charging voltage setting value for power storage unit 10 based on the detection result of the degradation state of power storage unit 10 by degradation detection unit 21. This also has the advantage of simplifying the configuration of charging circuit unit 11 and other components compared to a case where the charging voltage setting value is continuously changed.

[0095] Alternatively, degradation detection unit 21 may determine the degradation state of power storage unit 10 as being in one of three or more degradation stages by comparing the degradation level calculated based on the internal resistance and capacitance of power storage unit 10 with each of a plurality of threshold values. In other words, there are multiple threshold values, and degradation detection unit 21 determines the degradation state of power storage unit 10 as being in one of three or more degradation stages by comparing the degradation state of power storage unit 10 with each of the plurality of threshold values. In this case, control unit 22 sets a charge voltage set value for each of the three or more degradation stages. Specifically, if any two of the three or more degradation stages are set as a low degradation stage and a high degradation stage (more severe than the low degradation stage), control unit 22 sets the charge voltage set value for the low degradation stage to a voltage lower than the charge voltage set value for the high degradation stage. Specifically, control unit 22 controls the charging voltage setting value in each of the three or more degradation stages to a voltage value lower than the setting value in other degradation stages that are more severe than the aforementioned degradation stages. This allows the charging voltage setting value to be set to a lower voltage value in a low degradation stage, where degradation is less severe than in a high degradation stage. This suppresses degradation of power storage unit 10 and delays the onset of degradation.

[0096] (3.2) Other variations

[0097] In the basic configuration, when comparing two values, such as voltage measurement results, "above" can also mean "greater than." That is, whether or not the comparison includes equality can be arbitrarily changed based on the setting of a reference value, etc., so there is no technical difference between "above" and "greater than." Similarly, "less than" can also mean "less than."

[0098] In the basic embodiment, the semiconductor switching elements included in the charging circuit unit 11 are not limited to MOSFETs and may also be semiconductor switching elements such as IGBTs (Insulated Gate Bipolar Transistors). Furthermore, the circuit configuration of the charging circuit unit 11 can be modified as appropriate, and may also include a DC / DC converter capable of buck-boost operations. Furthermore, the semiconductor switching elements included in the output circuit unit 12 are not limited to MOSFETs and may also be semiconductor switching elements such as IGBTs. Furthermore, the circuit configuration of the output circuit unit 12 can also be modified as appropriate, and may also include a DC / DC converter capable of buck-boost operations.

[0099] In a basic embodiment, power storage unit 10 may be a secondary battery such as a lithium ion capacitor (LIC) or a lithium ion battery (LIB). In a lithium ion capacitor, the positive electrode is formed of the same material as an EDLC (e.g., activated carbon), and the negative electrode is formed of the same material as a LIB (e.g., a carbon material such as graphite).

[0100] In addition, the storage unit 10 is not limited to an electric double layer capacitor, and may be, for example, an electrochemical device having a structure as described below. The electrochemical device mentioned here comprises a positive electrode component, a negative electrode component, and a non-aqueous electrolyte. The positive electrode component comprises a positive electrode current collector and a positive electrode material layer supported on the positive electrode current collector and containing a positive electrode active material. The positive electrode material layer contains a conductive polymer as a positive electrode active material capable of doping and dedoping anions (dopant). The negative electrode component comprises a negative electrode material layer containing a negative electrode active material. The negative electrode active material is, for example, a substance for a redox reaction accompanied by the absorption and release of lithium ions, specifically a carbon material, a metal compound, an alloy, or a ceramic material. The non-aqueous electrolyte has lithium ion conductivity, for example. This non-aqueous electrolyte contains a lithium salt and a non-aqueous solution that dissolves the lithium salt. An electrochemical device of this structure has a higher energy density than an electric double layer capacitor, etc.

[0101] In the basic embodiment, the backup power supply system 1 is described as being mounted on an automobile. However, the backup power supply system 1 can also be mounted on a mobile object such as an airplane, a ship, or a train. Furthermore, the backup power supply system 1 is not limited to being mounted on a mobile object and can also be installed and used in a facility or the like.

[0102] (Summarize)

[0103] Based on the above-described embodiments and the like, the following aspects are disclosed.

[0104] A backup power supply system (1) of the first embodiment includes a first port (P1), a second port (P2), a charging circuit unit (11), an output circuit unit (12), a degradation detection unit (21), and a control unit (22). The first port (P1) can be connected to a power supply (2). The second port (P2) can be connected to a load (3). The charging circuit unit (11) charges the storage unit (10) using power input from the power supply (2) via the first port (P1) so that the voltage of the storage unit (10), i.e., the charging voltage, reaches a set value. The output circuit unit (12) supplies power from the storage unit (10) to the load (3) via the second port (P2) when the power supply (2) is turned off. The degradation detection unit (21) detects the degradation state of the storage unit (10). The control unit (22) controls the set value of the charging voltage when the charging circuit unit (11) charges the storage unit (10) based on the detection result of the degradation detection unit (21).

[0105] According to this method, for example, the control unit (22) can control the setting value of the charging voltage to a value lower than that at the end of the life of the power storage unit (10) at the initial use stage when the capacitance of the power storage unit (10) is larger and the internal resistance is smaller than that at the end of the life of the power storage unit (10). The higher the setting value of the charging voltage, the more likely the power storage unit (10) is to deteriorate more seriously. Therefore, by controlling the setting value of the charging voltage to a voltage value lower than that at the end of the life of the power storage unit (10), for example, at the initial use stage, the control unit (22) can suppress the degradation of the power storage unit (10) and extend the life of the power storage unit (10).

[0106] As a second embodiment of the backup power supply system (1), in the first embodiment, the control unit (22) controls the setting value of the charging voltage to a higher voltage value as the degradation of the storage unit (10) becomes more serious.

[0107] According to this method, for example, the set value of the charging voltage can be controlled to a lower voltage value than that at the end of the lifespan at the initial stage of use, thereby suppressing the degradation of the storage unit (10). In addition, the control unit (22) controls the set value of the charging voltage to a higher voltage value as the degradation of the storage unit (10) becomes more serious, thereby being able to supply the power required for the operation of the load (3) even when the capacitance of the storage unit (10) decreases.

[0108] As a backup power supply system (1) of a third embodiment, in the first embodiment, a degradation detection unit (21) determines that the degradation state of the power storage unit (10) is at one of a first degradation stage in which the degradation state level is below a predetermined threshold value, and a second degradation stage in which the degradation state level exceeds the threshold value. A control unit (22) controls a set value of a charging voltage in the second degradation stage to a voltage value higher than the set value of the charging voltage in the first degradation stage.

[0109] According to this aspect, degradation of the power storage unit (10) can be suppressed by setting the setting value of the charging voltage in the first degradation stage to a voltage value lower than the setting value of the charging voltage in the second degradation stage.

[0110] As a fourth embodiment of the backup power supply system (1), in the first embodiment, the degradation detection unit (21) compares the degradation state of the power storage unit (10) with a plurality of threshold values ​​to determine that the power storage unit (10) is in one of three or more degradation stages. The control unit (22) controls the setting value of the charging voltage in each of the three or more degradation stages to a voltage value lower than the setting value of the charging voltage in other degradation stages that are more severely degraded than the above-mentioned degradation stages among the three or more degradation stages.

[0111] According to this embodiment, the control unit (22) can suppress degradation of the power storage unit (10) by controlling the set value of the charging voltage in the low degradation stage to a voltage value lower than the set value of the charging voltage in the high degradation stage.

[0112] As a fifth embodiment of the backup power supply system (1), in any one of the first to fourth embodiments, the control unit (22) controls the set value of the charging voltage to a voltage value that can supply the load (3) with the power required to perform a specified action based on the detection result of the degradation detection unit (21).

[0113] According to this embodiment, the backup power supply system (1) can supply electric power required for performing a predetermined operation from the power storage unit (10) to the load (3) when the power supply (2) is in a power-off state.

[0114] As a sixth embodiment, a backup power supply system (1) is provided in any one of the first to fifth embodiments, wherein the power supply (2) and the load (3) are mounted on a vehicle (100). The backup power supply system (1) includes a discharge circuit unit (14). When a discharge command is input from a control unit (22), the discharge circuit unit (14) discharges the charge stored in the storage unit (10). When the control unit (22) receives stop information indicating that the vehicle (100) is stopped, the control unit (22) outputs a discharge command to the discharge circuit unit (14).

[0115] According to this method, when the vehicle (100) stops, the backup power supply system (1) does not need to supply power to the load (3), so the control unit (22) controls the discharge circuit unit (14) to reduce the terminal voltage of the storage unit (10), thereby further suppressing the degradation of the storage unit (10).

[0116] As a seventh embodiment of the backup power supply system (1), in the sixth embodiment, the control unit (22) controls the discharge amount of the discharge circuit unit (14) from the storage unit (10) based on the stop information and the degradation state of the storage unit (10).

[0117] According to this aspect, the control unit (22) controls the discharge amount from the power storage unit (10) based on the stop information and the degradation state of the power storage unit (10), thereby being able to control the discharge amount to an appropriate value.

[0118] As an eighth aspect, in the backup power supply system (1) according to any one of the first to seventh aspects, the power storage unit (10) includes an electric double layer capacitor.

[0119] According to this embodiment, even when the power storage unit (10) includes an electric double layer capacitor, degradation of the electric double layer capacitor can be suppressed.

[0120] A ninth embodiment of a method for controlling a backup power supply system is a method for controlling a backup power supply system (1) having a first port (P1), a second port (P2), a charging circuit unit (11), and an output circuit unit (12), the method comprising a degradation detection process and a control process. The first port (P1) is connectable to a power supply (2). The second port (P2) is connectable to a load (3). The charging circuit unit (11) is configured to charge the storage unit (10) using power input from the power supply (2) via the first port (P1) so that the voltage of the storage unit (10), i.e., the charging voltage, reaches a set value. The output circuit unit (12) is configured to supply power from the storage unit (10) to the load (3) via the second port (P2) when the power supply (2) is disconnected. The degradation state of the storage unit (10) is detected in the degradation detection process. In the control process, a setting value of a charging voltage when a charging circuit unit (11) charges the power storage unit (10) is controlled based on a detection result of a degradation state of the power storage unit (10).

[0121] According to this method, for example, in the initial use period when the capacitance of the storage unit (10) is larger and the internal resistance is smaller than at the end of the life of the storage unit (10), the set value of the charging voltage can be controlled to a voltage value lower than that at the end of the life. As the terminal voltage of the storage unit (10) increases, the degradation of the storage unit (10) becomes more serious. Therefore, for example, by controlling the set value of the charging voltage in the initial use period to a voltage value lower than that at the end of the life, the degradation of the storage unit (10) can be suppressed.

[0122] Not limited to the above-mentioned method, various structures (including modified examples) of the backup power supply system (1) of the above-mentioned embodiment can also be realized by a control method of the backup power supply system (1), a (computer) program or a non-temporary recording medium recording the program.

[0123] The structures of the second to eighth modes are not essential structures of the backup power supply system (1) and can be omitted as appropriate.

[0124] In addition, the sixth and seventh modes are modes that can be implemented independently, and are not necessarily based on any of the first to fifth modes. That is, the backup power supply system (1) of the sixth mode only needs to be mounted on the vehicle (100) and include a first port (P1), a second port (P2), a charging circuit unit (11), an output circuit unit (12), a control unit (22), and a discharge circuit unit (14). The first port (P1) can be connected to the power supply (2). The second port (P2) can be connected to the load (3). The charging circuit unit (11) charges the storage unit (10) using power input from the power supply (2) via the first port (P1). The output circuit unit (12) supplies power from the storage unit (10) to the load (3) via the second port (P2) when the power supply (2) is turned off. The discharge circuit unit (14) discharges the charge stored in the storage unit (10) when a discharge command is input from the control unit (22). When the control unit (22) obtains stop information indicating that the vehicle (100) is stopped, it outputs a discharge command to the discharge circuit unit (14). In this case, in the backup power supply system (1), it is not essential that the control unit (22) controls the charging circuit unit (11) to set a charging voltage value when charging the storage unit (10) based on the detection result of the degradation detection unit (21). The charging voltage of the storage unit (10) can also be set to a constant voltage value.

[0125] Marking Description

[0126] 1 Backup power system

[0127] 2 Power supply

[0128] 3 Load

[0129] 10. Power storage unit

[0130] 11 Charging circuit

[0131] 12 Output circuit

[0132] 14 Discharge circuit

[0133] 21 Degradation Detection Unit

[0134] 22 Control Unit

[0135] 100 vehicles

[0136] P1 port 1

[0137] P2 port 2

Claims

1. A backup power system comprising: Port 1, can be connected to the power supply; The second port can be connected to the load; a charging circuit unit that charges the power storage unit using the power input from the power supply via the first port so that a voltage of the power storage unit, that is, a charging voltage, reaches a set value; an output circuit unit that supplies electric power from the power storage unit to the load via the second port in a power-off state in which the power source is turned off; a degradation detection unit configured to detect a degradation state of the power storage unit; as well as The control unit controls the set value based on the detection result of the degradation detection unit.

2. The backup power system according to claim 1, The control unit controls the set value of the charging voltage to a higher voltage value as degradation of the power storage unit becomes more severe.

3. The backup power system according to claim 1, The degradation detection unit determines that the degradation state of the power storage unit is at one of a first degradation stage in which the level of the degradation state is equal to or lower than a predetermined threshold value, and a second degradation stage in which the level of the degradation state exceeds the threshold value. The control unit controls the set value of the charging voltage in the second degradation stage to a voltage value higher than the set value of the charging voltage in the first degradation stage.

4. The backup power system according to claim 1, The degradation detection unit determines that the degradation state of the power storage unit is in one of three or more degradation stages by comparing the degradation state of the power storage unit with a plurality of threshold values. The control unit controls the set value of the charging voltage in each of the three or more degradation stages to be a voltage value lower than the set value of the charging voltage in other degradation stages among the three or more degradation stages that are more severely degraded than the respective degradation stages.

5. The backup power supply system according to claim 1, The control unit controls the set value of the charging voltage to a voltage value capable of supplying the load with power required for the load to perform a predetermined operation based on the detection result of the degradation detection unit.

6. The backup power supply system according to claim 1, The power source and the load are mounted on a vehicle. The backup power supply system includes a discharge circuit unit that discharges the charge stored in the storage unit when a discharge command is input from the control unit. The control unit outputs the discharge command to the discharge circuit unit upon acquiring the stop information indicating that the vehicle is stopped.

7. The backup power supply system according to claim 6, The control unit controls a discharge amount of the power storage unit discharged by the discharge circuit unit based on the stop information and a degradation state of the power storage unit.

8. The backup power supply system according to claim 1, The power storage unit includes an electric double layer capacitor.

9. A method for controlling a backup power system, comprising: Steps of preparing a backup power system, the backup power system comprising: Port 1, can be connected to the power supply; The second port can be connected to the load; a charging circuit unit configured to charge the power storage unit using the power input from the power supply via the first port so that a voltage of the power storage unit, that is, a charging voltage, reaches a set value; as well as an output circuit unit configured to supply electric power from the power storage unit to the load via the second port in a power-off state in which the power source is turned off; The control method of the backup power system further includes: detecting a degradation state of the power storage unit; as well as a step of controlling the set value based on a result of detecting a degradation state of the power storage unit.

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