Backup power system and vehicle

Abstract

This backup power supply system is provided with a detection unit, an electric storage unit, and a control unit, wherein: the detection unit detects an abnormality in a power supply for supplying electric power to multiple loads; the electric storage unit supplies electric power to multiple loads when the detection unit has detected an abnormality in the power supply; and the control unit monitors the level of electric energy remaining in the electric storage unit, and limits the loads to which electric power is to be supplied by the storage unit in the case when the level of electric energy remaining in the storage unit falls below a threshold value of electric energy.

Description

[Technical field]

[0001] The present disclosure relates to a backup power supply system and a vehicle, and more particularly to a backup power supply system including a backup power storage unit for a power supply that supplies power to a plurality of loads, and a vehicle equipped with the backup power supply system. [Background technology]

[0002] The vehicle backup device described in Patent Document 1 backs up multiple drive sources with power supply from a second power source unit (power storage unit) when power supply from a first power source unit (power source) is cut off. In this backup device, when the control unit detects an abnormal state of power supply from the first power source unit, it instructs the discharge unit to intermittently flow a discharge current from the second power source unit to each of the multiple drive sources multiple times. The control unit also controls the supply destination of the discharge current so that each instruction time for instructing the discharge unit to flow the discharge current from the second power source unit to each of the multiple drive sources is shifted from each instruction time for instructing the discharge unit to flow the discharge current from the second power source unit to the other drive sources. That is, 2nd power supply section The power from the power supply is supplied to the multiple drive sources in a time-division manner, which prevents the discharge current from concentrating on multiple drive sources at the same time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 061750 Summary of the Invention

[0004] In the backup device (backup power supply system) described in Patent Document 1, power from a second power supply unit is supplied to a plurality of driving sources (loads) in a time-division manner. Remaining When the amount of power becomes low, it may not be possible to supply power to an important driving source (load).

[0005] The present disclosure has been made in consideration of the above problems, and has an object to provide a backup power supply system that can supply power to important loads on a priority basis even when the remaining power amount in a power storage unit becomes low, and a vehicle equipped with the backup power supply system.

[0006] A backup power supply system according to an aspect of the present disclosure includes a detection unit, a power storage unit, and a control unit. The detection unit detects an abnormality in a power supply that supplies power to a plurality of loads. The power storage unit supplies power to the plurality of loads when the detection unit detects an abnormality in the power supply. The control unit monitors the remaining power of the power storage unit, and limits the load to which the power storage unit supplies power when the remaining power of the power storage unit falls below a threshold power amount. The value of the output voltage of the power storage unit corresponding to the threshold amount of power is set as a threshold voltage. The control unit monitors the remaining amount of power of the power storage unit by monitoring the output voltage of the power storage unit, and determines that the remaining amount of power of the power storage unit has fallen below the threshold amount of power when the output voltage of the power storage unit falls below the threshold voltage. When the remaining amount of power of the power storage unit falls below the threshold amount of power, the control unit supplies power from the power storage unit only to a specific load among the multiple loads. Loads among the multiple loads other than the specific load are set as non-specific loads. The amount of voltage that drops in the output voltage of the power storage unit when the specific load starts operating is set as a voltage drop amount. The threshold voltage is set using the voltage drop amount related to the specific load.

[0007] A vehicle according to an aspect of the present disclosure includes the backup power supply system according to the aspect described above, and a vehicle body mounting the backup power supply system.

[0008] The present disclosure has an effect of being able to supply power preferentially to important loads even when the remaining amount of power in the power storage unit is low. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view, partly in section, showing a vehicle equipped with a backup power supply system according to an embodiment. [Diagram 2] FIG. 2 is a block diagram of a backup power supply system according to an embodiment. [Diagram 3] FIG. 3 is a timing chart illustrating how to determine the threshold voltage. [Figure 4] FIG. 4 is an explanatory diagram for explaining the operation of a main part (switch control part) of the control circuit. [Diagram 5] FIG. 5 is an explanatory diagram illustrating the operation of a main part (switch control part) of the control circuit of the second modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment) The embodiment and modified examples described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiment and modified examples. Various modifications other than the embodiment and modified examples are possible according to the design, etc., as long as they do not deviate from the technical idea of ​​the present disclosure.

[0011] (overview) A backup power supply system 1 according to this embodiment will be described with reference to Fig. 2. When an abnormality occurs in the main power supply 4, the backup power supply system 1 according to this embodiment supplies power to a plurality of electrical devices 5 (loads) in place of the main power supply 4. This allows the plurality of electrical devices 5 to continue operating using power supplied from the backup power supply system 1 even when the power supply from the main power supply 4 is stopped.

[0012] The backup power supply system 1 is mounted on a vehicle (a mobile body that runs on wheels, for example, a four-wheeled automobile) 9 for use (FIG. 1). The vehicle 9 includes a drive system 10 and a vehicle body 91 (vehicle main body) on which the drive system 10 is mounted. The drive system 10 includes the backup power supply system 1, a main power source 4, and multiple electrical devices 5. The main power source 4 is a battery (for example, a lead-acid battery) mounted on the vehicle, and is configured to supply power to the multiple electrical devices 5.

[0013] In this embodiment, the plurality of electric devices 5 include two electric devices, that is, a shift-by-wire system 50 and a brake system 60. In this embodiment, the plurality of electric devices 5 include two electric devices, that is, the shift-by-wire system 50 and the brake system 60, but the number of electric devices 5 may be three or more.

[0014] The shift-by-wire system 50 is a system that electrically switches the shift range of an automatic transmission mounted on a vehicle. The shift-by-wire system 50 includes a drive control unit 51 and an actuator 52. The drive control unit 51 controls the drive of the actuator 52 by outputting a control signal to the actuator 52 based on the position of a shift lever operated by a driver. The actuator 52 is configured to switch the shift range of the automatic transmission 6 in response to the control signal from the drive control unit 51.

[0015] The shift ranges of the automatic transmission include a parking range (P range), a reverse range (R range), a neutral range (N range), and a drive range (D range). The drive range is used when the vehicle is moving forward, the reverse range is used when the vehicle is moving backward, and the parking range is used when the vehicle is parked. In the parking range, the actuator 52 locks the rotating shaft in the automatic transmission, thereby locking the movement of the vehicle.

[0016] The brake system 60 is a system that electrically operates a brake mechanism provided on each wheel of the vehicle. The brake system 60 includes a drive control unit 61 and an actuator 62. The drive control unit 61 controls the drive of the actuator 62 by outputting a control signal to the actuator 62 based on the amount of operation of the brake pedal by the driver. The actuator 62 is configured to operate the brake mechanism provided on each wheel in response to the control signal from the drive control unit 61 to apply the brakes to each wheel.

[0017] The shift-by-wire system 50 and the brake system 60 are configured to operate by power supply from the main power supply 4 or the backup power supply system 1.

[0018] When the main power supply 4 is normal, power is supplied from the main power supply 4 to the multiple electrical devices 5 (i.e., the systems 50, 60). On the other hand, when an abnormality occurs in the main power supply 4, power is supplied from the backup power supply system 1 to the multiple electrical devices 5. Therefore, even when an abnormality occurs in the main power supply 4, the multiple electrical devices 5 can operate in response to the driver's operation. An abnormality in the main power supply 4 refers to, for example, a drop in the output voltage of the main power supply 4 below a predetermined voltage value due to a breakdown or deterioration of the main power supply 4 (i.e., a power failure).

[0019] In this embodiment, when the remaining power amount of the backup power supply system 1 becomes low, the electric appliances 5 to which power is supplied are limited. That is, among the multiple electric appliances 5, power is supplied only to specific electric appliances 5 (specific loads), and power supply to other electric appliances 5 (non-specific loads) is stopped. This allows power to be supplied preferentially to important electric appliances (i.e., specific electric appliances) 5, ensuring the operation of the important electric appliances 5.

[0020] (composition) As shown in FIG. 2, the backup power supply system 1 of this embodiment includes a power storage unit 20, a charge / discharge circuit 21 (transformer circuit), a power supply circuit 22, a control circuit 3, a plurality of switches SW1, SW2, diodes D5 to D9, a communication unit 23, a plurality of (e.g., two) input terminals T1 to T2, a plurality of (e.g., two) output terminals T4, T5, and electrical circuits DR7 to DR13.

[0021] Here, a main power supply 4 is connected to a main electric circuit DR1, and a plurality of branch electric circuits DR2 to DR4 are connected to the main electric circuit DR1. Power from the main power supply 4 is supplied to the backup power supply system 1 and a plurality of electric devices 5 via the main electric circuit DR1 and the plurality of branch electric circuits DR2 to DR4.

[0022] The input terminal T1 is connected to the main circuit via the branch circuit DR2. DR1(and therefore the main power supply 4) and inputs power from the main power supply 4. The input terminal T2 is connected to the main electric circuit DR1 via the ignition switch SW3 and inputs an on signal or off signal from the ignition switch SW3. The output terminal T3 is connected to the branch circuit DR3 via the electric circuit DR5 and outputs power to the shift-by-wire system 50. The output terminal T4 is connected to the branch circuit DR4 via the electric circuit DR6 and outputs power to the brake system 60.

[0023] Branch line DR3 and line DR5 Diodes D1 and D2 are connected to the output terminal T3 and the branch path DR3, respectively. The cathodes of the diodes D1 and D2 are connected to each other and connected to the shift-by-wire system 50. The diodes D1 and D2 output power from the output terminal T3 or the branch path DR3, whichever has a higher voltage, to the shift-by-wire system 50. That is, when the voltage of the output terminal T3 is higher, the diode D2 is conductive and the diode D1 is non-conductive, so that the power from the output terminal T3 is output to the shift-by-wire system 50 via the diode D2. When the voltage of the branch path DR3 is higher, the diode D1 is conductive and the diode D2 is non-conductive, so that the power from the branch path DR3 is output to the shift-by-wire system 50 via the diode D1.

[0024] When no abnormality occurs in the main power supply 4, the switch SW1 is turned off as described below. Therefore, the voltage of the branch path DR3 becomes higher than that of the output terminal T3, so that the diode D1 becomes conductive and the diode D2 becomes non-conductive. As a result, the power from the branch path DR3 (i.e., the main power supply 4) is output to the shift-by-wire system 50. In this case, the switch SW1 is turned off, so that the output terminal T3 (i.e., the power storage unit 20) and the shift-by-wire system 50 are electrically disconnected. On the other hand, when an abnormality occurs in the main power supply 4, the switch SW1 is turned on as described below. Therefore, the voltage of the output terminal T3 becomes higher than that of the branch path DR3, so that the diode D1 becomes non-conductive and the diode D2 becomes conductive. As a result, the power from the output terminal T3 (i.e., the power storage unit 20) is output to the shift-by-wire system 50. In this case, the diode D1 becomes non-conductive, so that the main power supply 4 and the shift-wire system 50 are electrically disconnected.

[0025] Similarly, diodes D3 and D4 are connected to the electric path DR6 and the branch path DR4, respectively. The cathodes of the diodes D3 and D4 are connected to each other and to the brake system 60. Each of the diodes D3 and D4 outputs power from either the output terminal T4 or the branch path DR4, whichever has a higher voltage, to the brake stem 60.

[0026] When no abnormality occurs in the main power supply 4, the switch SW2 is turned off as described below. Therefore, the voltage of the branch path DR4 is higher than that of the output terminal T4, so that the diode D4 is conductive and the diode D3 is non-conductive. As a result, power from the branch path DR4 (i.e., the main power supply 4) is output to the brake system 60. In this case, by turning off the switch SW2, the output terminal T4 (i.e., the power storage unit 20) and the brake system 60The main power supply 4 is electrically disconnected from the brake system 51. On the other hand, when an abnormality occurs in the main power supply 4, the switch SW2 is turned on as described below. Therefore, the voltage at the output terminal T4 is higher than that at the branch path DR4, so that the diode D3 is rendered conductive and the diode D4 is rendered non-conductive. As a result, the power from the output terminal T4 (i.e., the power storage unit 20) is output to the brake system 60. In this case, the diode D4 is rendered non-conductive, so that the main power supply 4 and the brake system 51 are electrically disconnected from each other.

[0027] Electrical circuits DR7 to DR9 are connected between the input terminal T1 and the two output terminals T3, T4. One end of the electrical circuit DR7 is connected to the input terminal T1, and the other end (connection point N1) of the electrical circuit DR7 is connected to one end of a plurality of (for example, two) electrical circuits DR8, DR9. One ends of the electrical circuits DR8, DR9 are each connected to the other end of the electrical circuit DR7, and the other ends of the electrical circuits DR8, DR9 are each connected to a plurality of output terminals T3, T4.

[0028] The electric circuit DR7 is provided with a diode D5, a charge / discharge circuit 21, and a diode D6 in this order from the input terminal T1 side to the connection point N1 side. D6, D7 The cathode of the diode D1 is connected to the connection point N1 side, and the anode of the diode D5 is connected to the input terminal T1 side.

[0029] The electric circuit DR7 is connected to the power storage unit 20 via the electric circuit DR10 at a connection point N2 between the charge / discharge circuit 21 and the diode D6. An input / output terminal of the power storage unit 20 is connected to the control circuit 3 via the electric circuit DR11, and the output voltage of the power storage unit 20 is input to the control circuit 3 via the electric circuit DR11. The cathode of the diode D5 is connected to the charge / discharge circuit 21, and the anode of the diode D5 is connected to the input terminal T1. The electric circuit DR12 is connected between the two connection points N1 and N3. The connection point N3 is a connection point between the diode D5 and the charge / discharge circuit 21. The electric circuit DR12 is provided with a diode D7. The cathode of the diode D7 is connected to the connection point N1, and the anode of the diode D7 is connected to the connection point N3.

[0030] The connection point N3 of the electric circuit DR7 is connected to the control circuit 3 via the electric circuit DR13. The electric circuit DR13 is provided with a diode D8 and a power supply circuit 22 in this order from the connection point N3 toward the control circuit 3. The cathode of the diode D8 is connected to the power supply circuit 22, and the anode of the diode D8 is connected to the connection point N3. The input end of the power supply circuit 22 is connected to the control circuit 3 via the electric circuit DR13, and the input voltage of the power supply circuit 22 (i.e., the output voltage of the main power supply 4) is input to the control circuit 3. A diode D9 is connected between the input terminal T2 and the power supply circuit 22. The cathode of the diode D9 is connected to the power supply circuit 22, and the anode of the diode D9 is connected to the input terminal T2. As a result, an on signal or an off signal of the ignition switch SW3 is input to the power supply circuit 22 via the diode D9. The two electric circuits DR8 and DR9 are provided with switches SW1 and SW2, respectively.

[0031] The power storage unit 20 is a backup (i.e., auxiliary or spare) power source for the main power source 4. The power storage unit 20 is, for example, an electric double layer capacitor (EDLC: Electrical Double Layer Capacitor ). The power storage unit 20 may be, for example, a secondary battery such as a lithium ion capacitor (LIC) or a lithium ion battery (LIB). The lithium ion capacitor is a capacitor in which the positive electrode is made of a material similar to that of an EDLC (for example, activated carbon) and the negative electrode is made of a material similar to that of a LIB (for example, a carbon material such as graphite).

[0032] Further, each of the power storage units 20 is not limited to an electric double layer capacitor, and may be, for example, an electrochemical device having a configuration described below. The electrochemical device here includes a positive electrode member, a negative electrode member, and a non-aqueous electrolyte. The positive electrode member includes a positive electrode current collector and a positive electrode material layer supported on the positive electrode current collector and including a positive electrode active material. The positive electrode material layer includes a conductive polymer as a positive electrode active material that dopes and dedopes anions (dopants). The negative electrode member includes a negative electrode material layer including a negative electrode active material. The negative electrode active material is, for example, a material in which an oxidation-reduction reaction accompanied by the absorption and release of lithium ions proceeds, and specifically, is, for example, a carbon material, a metal compound, an alloy, or a ceramic material. The non-aqueous electrolyte has, for example, lithium ion conductivity. This type of non-aqueous electrolyte includes a lithium salt and a non-aqueous solution that dissolves the lithium salt. An electrochemical device having such a configuration has a higher energy density than an electric double layer capacitor or the like.

[0033] The power storage unit 20 may be configured with two or more power storage devices (such as electric double layer capacitors) electrically connected in parallel, in series, or in parallel and in series. That is, one power storage unit 20 may be realized by a parallel circuit or a series circuit of two or more power storage devices, or a combination thereof.

[0034] The charge / discharge circuit 21 is a circuit that charges and discharges the power storage unit 20 in response to control by the control circuit 3. The charge / discharge circuit 21 is, for example, a bidirectional step-up / step-down circuit. When the charge / discharge circuit 21 functions as a charge circuit, it inputs a voltage from the connection point N3 side, steps down the input voltage, and outputs it to the connection point N2 side. When the charge / discharge circuit 21 functions as a discharge circuit, it inputs a voltage from the connection point N2 side, steps up the input voltage, and outputs it to the connection point N3 side.

[0035] More specifically, the charge / discharge circuit 21 functions as a charging circuit when charging the power storage unit 20. In this case, the charge / discharge circuit 21 receives the output voltage of the main power supply 4 input to the input terminal T1 via a diode D5, steps down the input voltage, and outputs it to the power storage unit 20. As a result, the power storage unit 20 is charged by the output power of the main power supply 4.

[0036] Furthermore, when discharging the power storage unit 20 (i.e., when an abnormality occurs in the main power supply 4), the charge / discharge circuit 21 functions as a discharge circuit. In this case, the charge / discharge circuit 21 boosts the output voltage of the power storage unit 20 and outputs it to the connection point N3 (i.e., discharges it). As a result, the output power of the power storage unit 20 is output to the connection point N1 via the charge / discharge circuit 21 and the diode D7. Note that, until the output voltage of the power storage unit 20 is boosted by the charge / discharge circuit 21 (i.e., while the discharge voltage of the charge / discharge circuit 21 is lower than the output voltage of the power storage unit 20), the diode D6 is conductive and the diode D7 is non-conductive. Therefore, during this period, the output voltage of the power storage unit 20 is output to the connection point N1 via the diode D6. Then, when the output voltage of the power storage unit 20 is boosted by the charge / discharge circuit 21, the diode D7 is conductive and the diode D6 is non-conductive. As a result, the output voltage of the power storage unit 20 is output to the connection point N1 via the charge / discharge circuit 21 and the diode D7. The voltage output to the connection point N1 is output from the output terminal T3 via the switch SW1 and is also output from the output terminal T4 via the switch SW2. As a result, the output power of the power storage unit 20 is supplied from the output terminal T3 to the drive control unit 51 and the actuator 52 of the shift-by-wire system 50 and is also supplied from the output terminal T4 to the drive control unit 61 and the actuator 62 of the brake system 60.

[0037] In the backup power supply system 1 of the present embodiment, power is supplied to the drive control unit 51 and the actuator 52 of the shift-by-wire system 50 through the same electric path, but may be configured to supply power through different electric paths. In this case, the voltage values ​​of the voltages applied to the drive control unit 51 and the actuator 52 may be different from each other. Similarly, power is supplied to the drive control unit 61 and the actuator 62 of the brake system 60 through the same electric path, but may be configured to supply power through different electric paths. In this case, the voltage values ​​of the voltages applied to the drive control unit 61 and the actuator 62 may be different from each other.

[0038] The power supply circuit 22 is a circuit that generates an operating voltage for the control circuit 3. The power supply circuit 22 steps down the output voltage of the main power supply 4, which is input via the input terminal T1 and diodes D5 and D8, to a predetermined voltage (for example, 5 V) and outputs it to the control circuit 3. This allows the output power of the main power supply 4 to be supplied to the control circuit 3, enabling the control circuit 3 to operate. The power supply circuit 22 operates or stops in response to an on signal or off signal of the ignition switch SW3, which is input via the input terminal T2 and diode D9. That is, the power supply circuit 22 operates in response to an on signal of the ignition switch SW3, and stops in response to an off signal of the ignition switch SW3.

[0039] The communication unit 23 communicates (e.g., wired communication) with the multiple electric devices 5. For example, the communication unit 23 receives various instruction signals from the multiple electric devices 5 and outputs the received instruction signals to the control circuit 3. The control circuit 3 operates in response to the instruction signals from the multiple electric devices 5. Note that the various instruction signals include, for example, signals instructing the start and stop of charging and discharging the power storage unit 20. The instruction signals are, for example, PWM (Pulse Width Modulation) signals. That is, in this backup power supply system 1, charging and discharging of the power storage unit 20 can be controlled by instruction signals from the multiple electric devices 5.

[0040] Furthermore, when the backup power supply system 1 restricts the electric device 5 to which the power storage unit 20 supplies power, the communication unit 23 receives a notification informing the electric device 5 of the restriction from the control circuit 3 and transmits the received notification to the electric devices 5. This makes it possible to notify each electric device 5 that the electric device 5 to which the power storage unit 20 supplies power is restricted.

[0041] The notification unit 24 is a device that, when the backup power supply system 1 restricts the electric device 5 to which the power storage unit 20 supplies power, receives the details of the restriction from the control circuit 3 and notifies the driver (user) of the vehicle of the received details. The notification unit 24 is, for example, a display unit (e.g., an indicator) and is disposed, for example, on the instrument panel of the vehicle. The notification by the notification unit 24 can notify the driver of the vehicle that the electric device 5 to which the power storage unit 20 supplies power is restricted.

[0042] The multiple switches SW1, SW2 are provided in the multiple electric circuits DR8, DR9, respectively, and selectively switch between conduction and interruption of the multiple electric circuits DR8, DR9 in response to control of the control circuit 3. This selectively switches between outputting and stopping output voltages of the multiple output terminals T3, T4 in response to control of the control circuit 3. The switches SW1, SW2 are each configured of a semiconductor switching element (e.g., a MOSFET (Metal Oxide Semiconductor Field Effect Transistor)).

[0043] The control circuit 3 controls charging and discharging of the power storage unit 20, and also limits the electric device 5 to which the power storage unit 20 supplies power by controlling a plurality of switches SW1, SW2.

[0044] The control circuit 3 is a computer system (e.g., a microcontroller) mainly composed of a processor and a memory. The control circuit 3 realizes the functions of the control circuit 3 (an abnormality detection unit 31, a charge / discharge control unit 32, and a switch control unit 33, which will be described later) by executing a program stored in the memory with the processor. The program may be pre-recorded in the memory, or may be provided through a telecommunication line such as the Internet, or may be recorded and provided on a recording medium such as a memory card. The control circuit 3 is configured to start up when the ignition switch SW3 is turned on and power supply from the power supply circuit 22 begins.

[0045] The control circuit 3 includes an abnormality detection unit 31 (detection unit), a charge / discharge control unit 32, and a switch control unit 33 (control unit).

[0046] The abnormality detection unit 31 detects whether or not an abnormality has occurred in the main power supply 4 based on, for example, the output voltage of the main power supply 4 input to the control circuit 3 via the electric circuit DR13. For example, the abnormality detection unit 31 does not determine that an abnormality has occurred (i.e., does not detect an abnormality) when the voltage of the main power supply 4 is equal to or higher than a certain threshold, and determines that an abnormality has occurred when the voltage of the main power supply 4 is below the certain threshold, and detects an abnormality based on this abnormality determination.

[0047] When the abnormality detection unit 31 does not detect an abnormality in the main power supply 4, the charge / discharge control unit 32 controls the charge / discharge circuit 21 to charge the power storage unit 20 as described above. When the abnormality detection unit 31 detects an abnormality in the main power supply 4, the charge / discharge control unit 32 controls the charge / discharge circuit 21 to discharge the power storage unit 20 as described above. In this manner, by discharging the power storage unit 20 when an abnormality in the main power supply 4 is detected, the source of power supply to the multiple electrical devices 5 is switched from the main power supply 4 to the backup power supply system 1 (power storage unit 20), and momentary interruption of power supplied to the multiple electrical devices 5 is suppressed.

[0048] When controlling the charge / discharge circuit 21 to charge the power storage unit 20, if the output voltage of the power storage unit 20 is less than a first predetermined value, the charge / discharge control unit 32 controls the charge / discharge circuit 21 to charge the power storage unit 20 with a constant current, and when the output voltage of the power storage unit 20 is equal to or greater than the first predetermined value, the charge / discharge control unit 32 controls the charge / discharge circuit 21 to charge the power storage unit 20 with a constant voltage. When controlling the charge / discharge circuit 21 to discharge the power storage unit 20, the charge / discharge control unit 32 controls the charge / discharge circuit 21 to boost the output voltage (discharge voltage) of the power storage unit 20 to a second predetermined value (e.g., 9 V). The output voltage of the charge / discharge circuit 21 at this time is controlled to a voltage at which the multiple electric devices 5 can operate normally.

[0049] The switch control unit 33 controls the on / off switching of the multiple switches SW1 and SW2 based on the output voltage of the power storage unit 20 input to the control circuit 3 via the electric circuit DR11. More specifically, the switch control unit 33 monitors the output voltage of the power storage unit 20 by determining whether or not the output voltage of the power storage unit 20 has fallen below a threshold voltage.

[0050] When the abnormality detection unit 31 does not detect an abnormality in the main power supply 4, the switch control unit 33 controls the multiple switches SW1, SW2 all of the switches SW1, SW2 are controlled to be OFF. This stops the output of all output voltages from the multiple output terminals T3, T4. Furthermore, the switch control unit 33 controls all of the multiple switches SW1, SW2 to be ON from the time when the abnormality detection unit 31 detects an abnormality in the main power supply 4 until it determines that the output voltage of the power storage unit 20 has fallen below the threshold voltage. This causes the output power of the power storage unit 20 to be output from all of the multiple output terminals T3, T4. As a result, the output power of the power storage unit 20 can be supplied to the multiple electric devices 5 (i.e., the two systems 50, 60).

[0051] Furthermore, when the switch control unit 33 determines that the output voltage of the power storage unit 20 falls below the threshold voltage, it controls only a specific switch (e.g., SW1) of the multiple switches SW1 and SW2 to be on, and controls the other switch (e.g., SW2) to be off. As a result, the output power of the power storage unit 20 is output only from the output terminal T3 corresponding to the specific switch SW1 among the multiple output terminals T3 and T4, and the output power of the power storage unit 20 is not output from the output terminal T4 corresponding to the other switch SW2. As a result, the electric device 5 to which the power storage unit 20 supplies power is limited. More specifically, the output power of the power storage unit 20 is limited to a specific electric device 5 (e.g., the shift-by-wire system 50) among the multiple electric devices 5 (i.e., the two systems 50 and 60). 50 ) will be supplied only to

[0052] That is, in this backup power supply system 1, when the output voltage of the power storage unit 20 falls below the threshold voltage (in other words, when the remaining power of the power storage unit 20 falls below the threshold power amount (i.e., the threshold power amount corresponding to the threshold voltage)), the power storage unit 20 limits the electric appliances 5 to which it supplies power to only the specific electric appliances 5, thereby ensuring the supply of power to the specific electric appliances 5. This ensures the operation of the specific electric appliances 5.

[0053] The specific electric device 5 is the most important electric device (i.e., the electric device 5 that really needs power supply) among the multiple electric devices 5. This ensures the operation of the important electric device 5 even if the remaining power amount of the power storage unit 20 falls below the threshold power amount.

[0054] In this embodiment, the specific electric device 5 is the shift-by-wire system 50 out of the shift-by-wire system 50 and the brake system 60. This is because, assuming that the driver applies the brakes with the brake pedal to stop the vehicle on a slope and finally places the shift lever in the parking range to lock the automatic transmission (shift lock), the final shift lock can be performed even if the remaining amount of electric power in the power storage unit 20 is low.

[0055] In this embodiment, the threshold voltage is a voltage corresponding to the amount of power that allows the specific electric device 5 to operate at least once (for example, once). When the electric device 5 to which the power storage unit 20 supplies power is limited to the specific electric device 5, power supply from the power storage unit 20 to the other electric devices 5 is stopped. For this reason, in this embodiment, the threshold voltage is set to a voltage value (the smallest possible voltage value) corresponding to the amount of power that allows the specific electric device 5 to operate at least once (for example, once), making it difficult to limit the electric device 5 to which the power storage unit 20 supplies power.

[0056] Next, a method for determining the threshold voltage will be described with reference to Fig. 3. In this description, the model case of Fig. 3 is assumed. In the model case of Fig. 3, the multiple electric devices 5 include a shift-by-wire system 50 and a brake system 60, and the shift-by-wire system 50 is a specific electric device 5 (specific load), and the brake system 60 is an unspecified electric device 5 (unspecified load). In Fig. 3, the upper part is a timing chart of the output voltage V1 of the power storage unit 20, and the lower part is a timing chart of the output current I1 of the power storage unit 20.

[0057] 3, it is assumed that the driver operates the brake several times (e.g., three times) (i.e., the brake system 60, which is the non-specific electric device 5, operates several times (e.g., three times)) to stop the vehicle, and then the driver operates the shift lever to the parking range (i.e., the shift-by-wire system 50, which is the specific electric device 5, operates once). In other words, it is assumed that the operations of the two systems 50, 60 do not overlap with each other.

[0058] In this case, every time the brake system 60 operates once (i.e., every time the brake pedal is operated once), a current I_brake is supplied from the power storage unit 20 to the brake system 60. As a result, every time the brake system 60 operates once, a rectangular current waveform Ia is generated in the timing chart of the output current of the power storage unit 20. Furthermore, every time the shift-by-wire system 50 operates once (i.e., when the shift lever is operated to the parking range), a current I_sbw is supplied from the power storage unit 20 to the shift-by-wire system 50. As a result, every time the shift-by-wire system 50 operates once, a rectangular current waveform Ib is generated in the timing chart of the output current of the power storage unit 20.

[0059] The rising and falling times of each current waveform Ia correspond to the start and end of a single brake pedal operation, respectively. The rising and falling times of the current waveform Ib correspond to the start and end of a single operation of the shift lever to the parking range, respectively.

[0060] The output voltage V1 of the power storage unit 20 drops according to the current waveforms Ia and Ib of the output current I1 of the power storage unit 20. That is, the output voltage V1 of the power storage unit 20 suddenly drops at the start of each brake pedal operation, gradually drops during the operation, and returns to a constant voltage at the end of the operation. The lower the number of times the brake pedal is operated, the lower the lowest point of the voltage drop at each operation. When the shift lever is operated to the parking range, the output voltage V1 of the power storage unit 20 suddenly drops at the operation, gradually drops during the operation, and returns to a constant voltage at the end of the operation. The amount of voltage drop when the shift lever is operated to the parking range is greater than the amount of voltage drop during one brake pedal operation.

[0061] In this model case, it is considered that the voltage is restored when the brake pedal and the shift lever are each operated. In this case, the substantial voltage drop dV per shift lever operation in the output voltage V1 of the power storage unit 20 is the voltage drop dV1 during the entire shift lever operation minus the voltage recovery dV2 at the end of the brake pedal operation immediately before the shift lever operation (i.e., dV=dV1-dV2).

[0062] Here, the voltage drop amount dV1 is the sum of the voltage drop amount dV3 and the voltage drop amount dV4. The voltage drop amount dV3 is given by the product (I_sbw×R) of the current I_sbw at the start of the operation of the shift lever and the internal resistance R of the power storage unit 20 (i.e., dV3=I_sbw×R). The voltage drop amount dV4 is given by the value (I_sbw×dt / C) obtained by dividing the amount of change (I_sbw×dt) in the charge of the power storage unit 20 during the operation of the shift lever by the capacity C of the power storage unit 20 (i.e., dV4=I_sbw×dt / C). Note that the symbol dt is the operation time of the operation of the shift lever. The recovery voltage amount dV2 is given by the product (I_brake×R) of the current I_brake at the start of the operation of the brake pedal and the internal resistance R of the power storage unit 20 (i.e., dV2=I_brake×R). Therefore, the voltage drop The quantity dV is given by the formula in Equation 1.

[0063] dV=(I_sbw-I_brake)×R+I_sbw×dt / C...Formula 1

[0064] This voltage drop dV is a voltage corresponding to the amount of power that allows the shift-by-wire system 50 in this model case to operate once.

[0065] The threshold voltage Vth in this model case is given as the lowest of the lowest points among the lowest points during a plurality of operations of the brake system 60 when the lowest point of the voltage drop during the operation of the shift-by-wire system 50 coincides with the minimum guaranteed voltage Vmin of the power storage unit 20 (i.e., Vth=dV+Vmin). Therefore, the threshold voltage Vth is given by the calculation formula of Equation 2.

[0066] Vth=(I_sbw-I_brake)×R+I_sbw×dt / C+Vmin...Formula 2

[0067] The threshold voltage Vth is calculated using a voltage difference obtained by subtracting a recovery voltage amount dV2 of the non-specific electric device 5 (brake system 60) from a voltage drop amount dV1 of the specific electric device 5 (shift-by-wire system 50). The threshold voltage Vth is calculated using a value of a current I_sbw supplied to the specific electric device 5, an internal resistance R of the power storage unit 20, and a capacity C of the power storage unit 20.

[0068] In this embodiment, each current I_sbw, I_brake The values ​​of R and C are initially set. The internal resistance R and capacitance C are values ​​measured in the backup power supply system 1. The internal resistance R and capacitance C are also I_brake It may be initialized to the same value as

[0069] In this embodiment, the switch control unit 33 calculates the threshold voltage Vth using the arithmetic expression of Equation 2. The switch control unit 33 calculates the threshold voltage Vth using the arithmetic expression of Equation 2, for example, when the backup power supply system 1 is started up or when the abnormality detection unit 31 detects an abnormality in the main power supply 4.

[0070] Next, the operation of the switch control unit 33 will be described with reference to Fig. 4. Fig. 4 shows an example of a change over time in the output voltage V1 of the power storage unit 20. In the following description, it is assumed that the abnormality detection unit 31 detects an abnormality in the main power supply 4, and the switch control unit 33 controls all of the multiple switches SW1 and SW2 to be on, thereby supplying the output power of the power storage unit 20 to all of the multiple electrical devices 5. In this case, the switch control unit 33 monitors the output voltage V1 of the power storage unit 20 by periodically determining whether or not the output voltage V1 of the power storage unit 20 has fallen below the threshold voltage Vth.

[0071] The brake system 60 operates once between time points t1 and t2. More specifically, at time point t1, the brake system 60 starts to operate and the output voltage of the power storage unit 20 drops, and at time point t2, the brake system 60 stops to operate and the voltage returns. In this example, at time point t2, the output voltage V1 of the power storage unit 20 falls below the threshold voltage Vth. That is, the remaining amount of power in the power storage unit 20 drops to an amount of power that allows the specific electric device 5 (i.e., the shift-by-wire system 50) to operate once. As a result, the switch control unit 33 determines that the output voltage V1 falls below the threshold voltage Vth, and based on this determination result, controls only the specific switch SW1 of the multiple switches SW1 and SW2 to be turned on and controls the remaining switch SW2 to be turned off. As a result, the output power of the power storage unit 20 is supplied only to the specific electric device 5 (the shift-by-wire system 50) of the multiple electric devices 5, and is not supplied to the other electric devices 5 (the brake system 60). That is, only the specific electric device 5 is operable, and the other electric devices 5 are stopped. Therefore, even if the driver operates the other electric device 5 (the brake system 60), the other electric device 5 does not operate.

[0072] Then, at time t3, the specific electric device 5 (shift-by-wire system 50) starts operating, and ends the operation at time t4. This operation causes the shift lever to be operated into the parking range, and the movement of the vehicle is locked. In this manner, when the output voltage V1 of the power storage unit 20 falls below the threshold voltage Vth (i.e., when the remaining power amount of the power storage unit 20 falls below the threshold power amount), power is preferentially supplied to the specific electric device 5 (shift-by-wire system 50), which is an important electric device 5, to ensure the operation of the specific electric device 5.

[0073] (Modification) Modifications of the above embodiment will now be described. The following modifications may be implemented in combination.

[0074] (Modification 1) In the above embodiment, it is assumed that the remaining energy of the power storage unit 20 is monitored by monitoring the output voltage V1 of the power storage unit 20. However, the remaining energy of the power storage unit 20 may be directly monitored, and when the remaining energy falls below a threshold power amount, the electric device 5 to which the power storage unit 20 supplies power may be restricted. 。

[0075] (Variation 2) In the above embodiment, the threshold voltage Vth is calculated taking into consideration the voltage recovery at the end of the operation of the brake system 60, but it may be calculated without considering the voltage recovery at the end of the operation of the brake system 60. In this case, the threshold voltage Vth is given by the following calculation formula:

[0076] Vth=I_sbw×R+I_sbw×dt / C+Vmin...Equation 3

[0077] The formula 3 is a formula obtained by omitting the contribution of the return voltage amount dV2 from the formula 2. That is, the threshold voltage Vth in this modification is calculated by using the voltage drop amount dV1 of the specific electric device 5 (shift-by-wire system 50) without subtracting the return voltage amount dV2 of the non-specific electric device 5 (brake system 60).

[0078] In this modification, the time change of the output voltage V1 of the power storage unit 20 is assumed to be the time change of FIG. 5. That is, the brake system 60 operates once from time t11 to t12. More specifically, the brake system 60 starts to operate at time t11, the output voltage of the power storage unit 20 drops, and the brake system 60 ends its operation at time t2. In this case, the voltage does not return when the brake system ends its operation. In this example, the output voltage V1 of the power storage unit 20 falls below the threshold voltage Vth at time t12. As a result, the switch control unit 33 determines that the output voltage V1 falls below the threshold voltage Vth, and based on this determination result, controls only the specific switch SW1 of the multiple switches SW1 and SW2 to be turned on, and controls the remaining switch SW2 to be turned off. As a result, the output power of the power storage unit 20 is supplied only to the specific electric device 5 (shift-by-wire system 50) of the multiple electric devices 5, and is not supplied to the other electric devices 5 (brake system 60).

[0079] Then, at time t13, the specific electric device 5 (shift-by-wire system 50) starts operating, and ends the operation at time t14. This operation causes the shift lever to be operated into the parking range, and the movement of the vehicle is locked. In this modification as well, when the output voltage V1 of the power storage unit 20 falls below the threshold voltage Vth (i.e., when the remaining power amount of the power storage unit 20 falls below the threshold power amount), power is preferentially supplied to the specific electric device 5 (shift-by-wire system 50), which is an important electric device, to ensure the operation of the specific electric device 5.

[0080] (Variation 3) In the above embodiment, the switch control unit 33 has only one arithmetic formula (the arithmetic formula of Equation 2) for calculating the threshold voltage Vth, but when there are three or more electric devices 5, the switch control unit 33 may have multiple arithmetic formulas for calculating the threshold voltage Vth. In this case, the switch control unit 33 selects one arithmetic formula from the multiple arithmetic formulas in response to a change in the output voltage V1 of the power storage unit 20, and sets the threshold voltage Vth using the selected arithmetic formula.

[0081] More specifically, when the number of the electric devices 5 is three or more, there are a plurality of unspecified electric devices 5. The amount of voltage drop at the start of operation (i.e., how the voltage drops) and the amount of voltage recovery at the end of operation (i.e., how the voltage recovers) differ depending on the unspecified electric device 5. For this reason, an arithmetic expression for calculating the threshold voltage Vth is prepared for each unspecified electric device 5. In other words, a plurality of arithmetic expressions for calculating the threshold voltage Vth are stored in the switch control unit 33. Then, the power storage unit 20 Based on the manner in which the output voltage V1 of the non-specific electric device 5 is decreased or restored, the non-specific electric device 5 that is currently operating is determined, and the threshold voltage Vth is set using an arithmetic expression corresponding to the determined non-specific electric device 5. In this way, it is possible to set an optimal threshold voltage Vth according to the electric device 5 that is currently operating.

[0082] (Variation 4) In the above embodiment, the calculation formula (Formula 2) for calculating the threshold voltage Vth assumes a case where the operations of the two systems 50, 60 do not overlap, but it may assume a case where the operations of the two systems 50, 60 overlap. In this case, the threshold voltage Vth is given by the calculation formula in Formula 4.

[0083] Vth=(I_sbw+I_brake)×R+(I_sbw+I_brake)×dt / C+Vmin...Equation 4

[0084] (summary) The backup power supply system (1) of the first aspect includes a detection unit (31), a power storage unit (20), and a control unit (33). The detection unit (31) detects an abnormality in a power source (4) that supplies power to a plurality of loads (5). The power storage unit (20) supplies power to the plurality of loads (5) when the detection unit (31) detects an abnormality in the power source (4). The control unit (33) monitors the remaining power amount of the power storage unit (20), and when the remaining power amount of the power storage unit (20) falls below a threshold power amount, limits the load (5) to which the power storage unit (20) supplies power.

[0085] According to this configuration, when the remaining amount of power in the power storage unit (20) falls below the threshold amount of power, the loads (5) to which the power storage unit (20) can supply power are limited. Therefore, even when the remaining amount of power in the power storage unit (20) is low, power can be preferentially supplied to important loads (5).

[0086] In the backup power supply system (1) of the second aspect, in the first aspect, the control unit (33) supplies power from the power storage unit (20) to the multiple loads (5) from the time when the detection unit (31) detects an abnormality in the power source (4) until the remaining energy of the power storage unit (20) falls below a threshold energy amount.

[0087] According to this configuration, it is possible to suppress a decrease in the degree of freedom of operation of the load (5) from the time when the detection unit (31) detects an abnormality in the power source (4) until the remaining energy of the power storage unit (20) falls below the threshold energy (particularly immediately after the detection).

[0088] In the backup power supply system (1) of the third aspect, in the first or second aspect, a value of the output voltage (V1) of the power storage unit (20) corresponding to the threshold amount of power is set as a threshold voltage (Vth). The control unit (33) monitors the remaining amount of power in the power storage unit (20) by monitoring the output voltage (V1) of the power storage unit (20), and determines that the remaining amount of power in the power storage unit (20) has fallen below the threshold amount of power when the output voltage (V1) of the power storage unit (20) falls below the threshold voltage (Vth).

[0089] According to this configuration, the remaining energy of the power storage unit (20) is monitored by monitoring the output voltage (V1) of the power storage unit (20). Therefore, an expensive sensor such as a current sensor is not required, and the remaining energy of the power storage unit (20) can be monitored with an inexpensive configuration.

[0090] In the backup power supply system (1) of the fourth aspect, in the third aspect, when the remaining energy of the power storage unit (20) falls below a threshold energy, the control unit (33) supplies power from the power storage unit (20) only to a specific load (e.g., the shift-by-wire system 50) among the multiple loads (5).

[0091] According to this configuration, when the remaining amount of power in the power storage unit (20) falls below the threshold amount of power, power supply to a specific load (50) among the plurality of loads (5) can be ensured.

[0092] In the backup power supply system (1) of the fifth aspect, in the fourth aspect, the threshold amount of power is an amount of power that allows a specific load (50) to operate at least once.

[0093] According to this configuration, even if the remaining amount of power in the power storage unit (20) falls below the threshold amount of power, it is possible to ensure an amount of power sufficient to operate the specific load (50) at least once.

[0094] In the backup power supply system (1) of the sixth aspect, in the fourth or fifth aspect, among the multiple loads (5), the loads (60) other than the specific load (50) are defined as non-specific loads. In the output voltage (V1) of the power storage unit (20), the amount of voltage that drops when the specific load (50) starts operating is defined as a voltage drop amount (dV1), and the amount of voltage that returns when the non-specific load (60) stops operating is defined as a voltage recovery amount (dV2). The threshold voltage (Vth) is set using a voltage difference obtained by subtracting the voltage recovery amount (dV2) of the non-specific load (60) from the voltage drop amount (dV1) of the specific load (50).

[0095] According to this configuration, the threshold voltage (Vth) is set in consideration of the recovery voltage amount (dV2) generated when the operation of the non-specific load (60) ends, so that the threshold voltage (Vth) can be set with high accuracy. In other words, the threshold voltage (Vth) can be set to the lowest possible value.

[0096] In the backup power supply system (1) of the seventh aspect, in the fourth or fifth aspect, among the multiple loads (5), the loads (60) other than the specific load (50) are defined as non-specific loads. In the output voltage (V1) of the power storage unit (20), the amount of voltage that drops when the specific load (50) starts operating is defined as a voltage drop amount (dV1), and the amount of voltage that returns when the non-specific load (60) stops operating is defined as a voltage recovery amount (dV2). The threshold voltage (Vth) is set using the voltage drop amount (dV1) for the specific load (50) without subtracting the voltage recovery amount (dV2) for the non-specific load (60).

[0097] According to this configuration, the threshold voltage (Vth) does not take into account the recovery voltage amount (dV2) generated when the operation of the non-specific load (60) ends, and therefore the threshold voltage (Vth) can be calculated by a simple calculation.

[0098] In the backup power supply system (1) of the eighth aspect, in any one of the fourth to seventh aspects, the threshold voltage (Vth) is set using the value of the current (I_sbw) supplied to a specific load (50), the internal resistance (R) of the power storage unit (20), and the capacity (C) of the power storage unit (20).

[0099] According to this configuration, the threshold voltage (Vth) can be set using the value of the current (I_sbw) supplied to the specific load (50), the internal resistance (R) of the power storage unit (20), and the capacity (C) of the power storage unit (20).

[0100] In the backup power supply system (1) of the ninth aspect, in any one of the fourth to eighth aspects, the control unit (33) has a plurality of arithmetic expressions for calculating the threshold voltage (Vth), selects one of the plurality of arithmetic expressions in response to a change in the output voltage (V1) of the power storage unit (20), and sets the threshold voltage (Vth) using the selected arithmetic expression.

[0101] According to this configuration, the threshold voltage (Vth) can be set in response to a change in the output voltage (V1) of the power storage unit (20).

[0102] In the backup power supply system (1) of the tenth aspect, in any one of the third to ninth aspects, the threshold voltage (Vth) is initially set.

[0103] This configuration can reduce the processing load for calculating the threshold voltage (Vth).

[0104] The backup power supply system (1) of an eleventh aspect is any one of the first to tenth aspects, and further includes a notification unit (24) that notifies a user of the content of the limitation when the control unit (33) limits the load to which the power storage unit (20) supplies power.

[0105] According to this configuration, it is possible to inform the user of the content of the restriction.

[0106] The backup power supply system (1) of a twelfth aspect is any one of the first to eleventh aspects, and further includes a transformer circuit (21) that boosts an output voltage (V1) of the power storage unit (20) and outputs the boosted output voltage (V1) to a plurality of loads (5).

[0107] According to this configuration, the output voltage (V1) of the power storage unit (20) can be transformed and supplied to the load (5).

[0108] In the backup power supply system (1) of the thirteenth aspect, in any one of the first to twelfth aspects, the power supply (4) and the plurality of loads (5) are mounted on a vehicle body.

[0109] According to this configuration, the backup power supply system (1) can be applied to a vehicle.

[0110] A vehicle according to a fourteenth aspect includes the backup power supply system (1) according to any one of the first to thirteenth aspects, and a vehicle body having the backup power supply system (1) mounted thereon.

[0111] According to this configuration, a vehicle equipped with the backup power supply system (1) having the above-mentioned effects can be provided. [Explanation of symbols]

[0112] 1. Backup Power System 5 Electrical Equipment (Load) 20 Power storage unit 21 Charge / discharge circuit (transformer circuit) 24. Information Department 31 Anomaly detection unit (detection unit) 33 Switch control section (control section) 50 Shift-by-wire system (specific load) 60 Brake system (non-specific load) dV1 Voltage drop amount dV2 Recovery voltage amount C capacity R resistance V1 Output voltage Vth Threshold voltage

Claims

1. A detection unit that detects an abnormality in a power supply that supplies power to a plurality of loads; a power storage unit that supplies power to the plurality of loads when the detection unit detects an abnormality in the power supply; a control unit that monitors a remaining amount of power in the power storage unit, and limits a load to which power is supplied from the power storage unit when the remaining amount of power in the power storage unit falls below a threshold amount of power; a value of the output voltage of the power storage unit corresponding to the threshold amount of power is set as a threshold voltage; The control unit is monitoring an output voltage of the power storage unit to monitor a remaining amount of power of the power storage unit, and determining that the remaining amount of power of the power storage unit has fallen below the threshold amount of power when the output voltage of the power storage unit falls below the threshold voltage; When the remaining energy amount of the power storage unit falls below the threshold energy amount, the power storage unit supplies power to only a specific load among the plurality of loads; Among the plurality of loads, loads other than the specific loads are defined as non-specific loads; a voltage drop amount in the output voltage of the power storage unit when the specific load starts operating; the threshold voltage is set using the amount of voltage drop for the particular load; Backup power system.

2. The control unit supplies power from the power storage unit to the plurality of loads from a time when the detection unit detects an abnormality in the power supply until the remaining energy of the power storage unit falls below the threshold energy.

10. The backup power system of claim 1.

3. The threshold amount of power is an amount of power that allows the specific load to operate at least once.

3. The backup power system according to claim 1 or 2.

4. A recovery voltage amount is a voltage amount that is recovered when the operation of the non-specific load is terminated in the output voltage of the storage unit, The threshold voltage is set using a voltage difference obtained by subtracting the recovery voltage amount of the non-specific load from the drop voltage amount of the specific load. The backup power supply system according to any one of claims 1 to 3.

5. In the output voltage of the power storage unit, a voltage amount that is restored when the operation of the non-specific load is terminated is defined as a recovery voltage amount, The threshold voltage is set using the amount of voltage drop for the specific load without subtracting the amount of voltage recovery for the non-specific load. The backup power supply system according to any one of claims 1 to 3.

6. The threshold voltage is set using a value of a current supplied to the specific load, an internal resistance of the power storage unit, and a capacity of the power storage unit. The backup power supply system according to any one of claims 1 to 5.

7. The control unit has a plurality of arithmetic expressions for calculating the threshold voltage, selects one of the plurality of arithmetic expressions in response to a change in the output voltage of the storage unit, and sets the threshold voltage using the selected arithmetic expression. The backup power supply system according to any one of claims 1 to 6.

8. The threshold voltage is initially set. The backup power supply system according to any one of claims 1 to 7.

9. The power storage device further includes a notification unit that notifies a user of the content of the limitation when the control unit limits the load to which the power storage unit supplies power. The backup power supply system according to any one of claims 1 to 8.

10. Further comprising a transformer circuit that boosts an output voltage of the power storage unit and outputs the boosted output voltage to the plurality of loads. The backup power supply system according to any one of claims 1 to 9.

11. The power source and the plurality of loads are mounted on a vehicle body. The backup power supply system according to any one of claims 1 to 10.

12. A backup power supply system according to any one of claims 1 to 11, A vehicle body having the backup power supply system mounted thereon. vehicle.

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