Backup power system and mobile

Abstract

This back-up power supply system 1 supplies electric power from an electric storage device 5 to multiple loads 3 when a power supply 2 fails. The back-up power supply system 1 is equipped with a first voltage conversion circuit 6 for transforming an output voltage of the electric storage device 5. The multiple loads 3 comprise a first load 31 and a second load 32. The back-up power supply system 1 supplies the electric power from the electric storage device 5 to the first load 31 without passing through the first voltage conversion circuit 6, and supplies the electric power from the electric storage device 5 to the second load 32 through the first voltage conversion circuit 6.

Description

[Technical Field]

[0001] The present disclosure relates to a backup power supply system and a mobile body. More particularly, the present disclosure relates to a backup power supply system that supplies power to multiple loads in the event of a power supply failure, and a mobile body that includes the backup power supply system. [Background technology]

[0002] The boost power supply circuit (voltage conversion circuit) described in Patent Document 1 supplies power from a lithium ion battery (power storage device) that serves as a backup power supply to various loads when power supply from the battery is stopped. The boost power supply circuit boosts the DC voltage of the lithium ion battery and supplies power to the various loads. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-5481 Summary of the Invention

[0004] The above-mentioned boost power supply circuit boosts the output voltage of the lithium-ion battery and outputs it to various loads at once. Operational Certification It is necessary to boost all the power supplies together to match the load with the highest voltage, which increases the voltage and current processed inside the boost power supply circuit. As a result, the boost power supply circuit becomes larger and more expensive.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a backup power supply system and a mobile body that can reduce the cost of a voltage conversion circuit that transforms the output voltage of a power storage device.

[0006] A backup power supply system according to one aspect of the present disclosure is a backup power supply system that supplies power from a power storage device to multiple loads in the event of a power supply failure. The backup power supply system includes a voltage conversion circuit that transforms the output voltage of the power storage device. The multiple loads include a first load and a second load. The backup power supply system supplies power from the power storage device to the first load without passing through the voltage conversion circuit, and supplies power from the power storage device to the second load via the voltage conversion circuit. The voltage conversion circuit does not supply power to the second load when the power supply is normal, and supplies power to the second load when the power supply fails.

[0007] A mobile body according to one aspect of the present disclosure includes the backup power supply system and a mobile body.

[0008] The present disclosure has an effect of reducing the cost of a voltage conversion circuit that transforms the output voltage of a power storage device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a backup power supply system according to an embodiment. [Figure 2] FIG. 2 is a side view, with a part cut away, of a vehicle equipped with the backup power supply system. [Figure 3] FIG. 3 is a graph showing an example of the voltage and current output from the power storage device to the first load over time when a power supply failure occurs. [Figure 4] FIG. 4 is a graph showing an example of the voltage and current output from the power storage device to the second load over time when a power supply failure occurs. [Figure 5] FIG. 5 is a block diagram of a backup power supply system according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0010] (1. Embodiment) (1-1. Overall explanation) A backup power supply system 1 according to this embodiment will be described with reference to the drawings. The configuration described in this embodiment is merely an example of the present disclosure. The present disclosure is not limited to this embodiment, and various modifications can be made depending on the design, etc., as long as they do not deviate from the technical concept of the present disclosure.

[0011] As shown in FIG. 1, the backup power supply system 1 is mounted on, for example, a vehicle 9 (see FIG. 2), and supplies power from a power storage device 5 to a plurality of loads 3 when a power source 2 (for example, a battery) fails. This allows the plurality of loads 3 to continue operating by the power supply from the power storage device 5 even when the power source 2 fails. Here, "the power source 2 fails" means that the supply of power from the power source 2 to the loads 3 stops due to a malfunction, deterioration, or disconnection of the power source 2, etc.

[0012] In this way, the backup power supply system 1 is mounted on a vehicle 9 that includes a power source 2 and a plurality of loads 3. That is, the vehicle 9 (mobile body) includes a vehicle body 91 (mobile body body), a power source 2, a plurality of loads 3, and the backup power supply system 1. Note that, although the present embodiment illustrates an example in which the backup power supply system 1 is mounted on a vehicle 9, the backup power supply system 1 may also be mounted on a mobile body other than the vehicle 9 (for example, an airplane, a ship, or a train).

[0013] The plurality of loads 3 include a first load 31 and a second load 32 .

[0014] The first loads 31 are multiple loads 3 that satisfy the condition (first condition) of having higher power consumption (i.e., larger operating current) and the condition (second condition) of having a lower minimum guaranteed operating voltage compared to the second loads 32. The operating current is a current for operating the loads 3. The minimum guaranteed operating voltage is a voltage that guarantees operation of the loads 3. In other words, the first loads 31 are loads that require a large operating current but can tolerate a certain degree of reduction in operating voltage (i.e., tolerate a certain degree of reduction in operating voltage). Specifically, the first loads 31 include power system loads 3 (for example, a brake system of the vehicle 9 and an electric power steering system of the vehicle 9).

[0015] The second loads 32 are multiple loads 3 that satisfy the conditions of lower power consumption (i.e., lower operating current) and higher minimum guaranteed operating voltage compared to the first loads 31. That is, the second loads 32 are loads 3 that require a small operating current but a relatively high operating voltage (i.e., do not tolerate a drop in operating voltage). Specifically, the second loads 32 include loads 3 of control systems (for example, an ECU (Electronic Control Unit) of a brake system, an ECU of an electric power steering system, and devices related to ADAS (Advanced driver-assistance systems)).

[0016] The backup power supply system 1 of this embodiment includes a first voltage conversion circuit 6 (voltage conversion circuit) that transforms (boosts or bucks) the output voltage of the power storage device 5. Power from the power storage device 5 is supplied to a first load 31 (i.e., a load 3 that can tolerate a drop in operating voltage) without going through the first voltage conversion circuit 6. Power from the power storage device 5 is supplied to a second load 32 (i.e., a load 3 that cannot tolerate a drop in operating voltage) via the first voltage conversion circuit 6. In this way, the first voltage conversion circuit 6 transforms the output voltage only for some of the multiple loads 3 (e.g., the second load 32), so the first voltage conversion circuit 6 can be made smaller, and as a result, the cost of the first voltage conversion circuit 6 can be reduced. The backup power supply system 1 will be described in detail below.

[0017] (1-2. Detailed explanation of the backup power system) 1, backup power supply system 1 supplies the output power of power supply 2 to multiple loads 3 when there is no failure in power supply 2, and when there is a failure in power supply 2, it supplies the output power of power storage device 5 to multiple loads 3 in place of power supply 2. Backup power supply system 1 includes a power supply line 4, a power storage device 5, a first voltage conversion circuit 6 for backup, a second voltage conversion circuit 7 for charging, a bypass path 8, a diode 9, a first switch 10, a second switch 11, a selection switch 12, and a control circuit 13. Note that power storage device 5 does not necessarily have to be included as a component of backup power supply system 1.

[0018] (1-2-1.Power supply path) The power supply line 4 is a line for supplying the output power of the power source 2 to the plurality of loads 3 and the power storage device 5, and for supplying the output power of the power storage device 5 to the plurality of loads 3. The power supply line 4 has a first power supply line 41, a second power supply line 42, a third power supply line 43, and a fourth power supply line 44.

[0019] The first power supply path 41 is an electric path that supplies the output power of the power source 2 to the plurality of loads 3 (arrow F1 in FIG. 1). The first power supply path 41 has a main electric path 41a and a plurality of branch paths 41b. The main electric path 41a is connected to the output section of the power source 2. The plurality of branch paths 41b correspond to the plurality of loads 3. The plurality of branch paths 41b branch off from different positions on the main electric path 41a and are connected to the corresponding loads 3. In the main electric path 41a, the first load 31 is connected upstream (toward the power source 2) of the second load 32, and the second load 32 is connected downstream of the first load 31. In other words, the first load 31, which requires a large current, is connected upstream of the second load 32, which does not require a large current.

[0020] The second power supply line 42 and the third power supply line 43 are electric power supply lines for supplying the output power of the power storage device 5 to the plurality of loads 3.

[0021] The second power supply line 42 is an electric path for supplying the output power of the power storage device 5 to the first load 31 without passing through the first voltage conversion circuit 6 (arrow F2 in FIG. 1 ). The second power supply line 42 connects the input / output unit of the power storage device 5 to a branch point N1 of the first power supply line 41. The branch point N1 is arranged upstream of the multiple loads 3. The second power supply line 42 outputs the output power of the power storage device 5 to the branch point N1 of the main electric path 41a without passing through the first voltage conversion circuit 6. As a result, the output power of the power storage device 5 is supplied to the first load 31 without passing through the first voltage conversion circuit 6. Because the first load 31 tolerates a drop in operating voltage, the output power of the power storage device 5 is supplied to the first load 31 without passing through the first voltage conversion circuit 6.

[0022] The third power supply path 43 is an electric path for supplying the output power of the power storage device 5 to the second load 32 via the first voltage conversion circuit 6 (arrow F3 in FIG. 1 ). The third power supply path 43 connects an input / output unit of the power storage device 5 and a branch point N2 of the first power supply path 41. The branch point N2 is located at a position on the main electric path 41a between the first load 31 and the second load 32. That is, the branch point N2 is located upstream of the second load 32 and downstream of the first load 31 on the main electric path 41a. The third power supply path 43 is provided with a first voltage conversion circuit 6 that transforms the output voltage of the power storage device 5. The third power supply path 43 outputs the output voltage of the power storage device 5 to the branch point N2 of the main electric path 41a via the first voltage conversion circuit 6. As a result, the output power of the power storage device 5 is supplied to the second load 32 via the first voltage conversion circuit 6.

[0023] The fourth power supply line 44 is an electric path for supplying the output power of the power source 2 to the power storage device 5 (arrow F4 in FIG. 1). The fourth power supply line 44 connects the third branch point of the main electric path 41a and an input / output unit of the power storage device 5. The third branch point N3 is located upstream of the first branch point (on the power source 2 side) on the main electric path 41a. The fourth power supply line 44 is provided with a second voltage conversion circuit 7 that transforms the output voltage of the power source 2. The fourth power supply line 44 outputs the output voltage of the power source 2 to the power storage device 5 via the second voltage conversion circuit 7. As a result, the output power of the power source 2 is charged to the power storage device 5 via the second voltage conversion circuit.

[0024] (1-2-2. Energy storage device) The power storage device 5 is a backup (i.e., auxiliary or spare) power source for the power source 2. In other words, the power storage device 5 is a power source that can supply power to a plurality of loads 3 when the power source 2 fails. The power storage device 5 is, for example, an electric double layer capacitor (EDLC). The power storage device 5 may be configured with two or more power storage devices (e.g., electric double layer capacitors) electrically connected in parallel, in series, or in parallel and in series. In other words, the power storage device 5 may be realized by a parallel circuit or a series circuit of two or more power storage devices, or a combination thereof.

[0025] (1-2-3. Voltage conversion circuit) The first voltage conversion circuit 6 is a constant voltage circuit that transforms the output voltage of the power storage device 5 and outputs a constant voltage (first voltage), maintaining it at that voltage, and is provided on the third power supply path 43 as described above. The first voltage conversion circuit 6 is, for example, a step-up / step-down DC / DC converter. The first voltage is a voltage (e.g., 12 V) that is slightly higher than the minimum guaranteed operating voltage of the second load 32 (e.g., 11.5 V). As described above, the output power of the power storage device 5 is supplied to the second load 32 via the first voltage conversion circuit 6. As a result, even if the output voltage of the power storage device 5 drops, the voltage output from the power storage device 5 to the second load 32 is maintained at the first voltage, which is higher than the minimum guaranteed operating voltage.

[0026] The second voltage conversion circuit 7 is a constant voltage circuit (i.e., charging circuit) that transforms (e.g., boosts) the output voltage of the power supply 2, maintains it at a constant voltage (second voltage, e.g., 15 V), and outputs it to the power storage device 5 to charge the power storage device 5, and is provided on the fourth power supply path 44 as described above. The second voltage conversion circuit 7 is, for example, a step-up / step-down DC / DC converter. The second voltage is a voltage higher than the output voltage (e.g., 12 V) of the power supply 2. This allows the voltage of the power storage device 5 when fully charged to be higher than the output voltage of the power supply 2. As a result, the output current output from the power storage device 5 to the first load 31 via the second power supply path 42 can be made sufficiently large without passing through the first voltage conversion circuit 6.

[0027] (1-2-4. Bypass route) The bypass path 8 is an electric path connected in parallel to the first voltage conversion circuit 6, and is an electric path for ensuring the output voltage from the power storage device 5 to the second load 32 until the first voltage conversion circuit 6 is started up (i.e., from the start of start-up to the completion of start-up). In this embodiment, the bypass path 8 includes two bypass paths (a first bypass path 81 and a second bypass path 82).

[0028] The first bypass path 81 is an electrical path that shorts the input and output of the first voltage conversion circuit 6 in the third power supply line 43. That is, the first bypass path 81 is an electrical path that is separated from the power supply line from the power storage device 5 to the first load 31 via the second power supply line 42. The first bypass path 81 is provided with a diode 811 for preventing reverse current. The cathode of the diode 811 is connected to the output side of the first voltage conversion circuit 6, and the anode of the diode 811 is connected to the input side of the first voltage conversion circuit 6. The second bypass path 82 is an electrical path that is formed by the second power supply line 42 and a partial electrical path between the first branch point N1 and the second branch point N2 in the first power supply line 41. That is, the second bypass path 82 is an electrical path that utilizes the power supply line from the power storage device 5 to the first load 31 via the second power supply line 42.

[0029] The first bypass path 81 or the second bypass path 82 can prevent the output voltage from the power storage device 5 to the second load 32 from being interrupted until the first voltage conversion circuit 6 is started. In particular, the first bypass path 81 makes it possible to supply the output voltage from the power storage device 5 to the second load 32 without any interruption until the first voltage conversion circuit 6 is started. The second bypass path 82 interrupts the output voltage from the power storage device 5 to the second load 32 until the second switch 11 described below is turned on (i.e., from the start of turning on to the completion of turning on (e.g., 1 ms)). However, the time during which the output voltage of the power storage device 5 is interrupted can be made shorter than the time until the first voltage conversion circuit 6 is started (e.g., 100 ms). Note that if the tolerable time of instantaneous power failure of the second load 32 is longer than the time until the second switch 11 is turned on, the first bypass path 81 may be omitted.

[0030] (1-2-5. Diodes) The diode 9 is a reverse current prevention diode and is provided in the first power supply line 41 between the first load 31 and the second load 32. In this embodiment, the diode 9 is provided in the first power supply line 41 between the most downstream load 3 of the first loads 31 and the second branch point N2. The cathode of the diode 9 is connected to the second load 32 side, and the anode of the diode 9 is connected to the first load 31 side. The diode 9 prevents the current supplied from the power storage device 5 to the second load 32 via the third power supply line 43 or the bypass paths 81 and 82 from flowing back from the second load 32 to the first load 31 in the first power supply line 41. That is, the power supplied from the power storage device 5 to the second load 32 can be prevented from being taken by the first load 31.

[0031] (1-2-6. Switch) The first switch 10 is provided in the main electric path 41a of the first power supply path 41, and is switched on and off under the control of the control circuit 13 to connect and disconnect the main electric path 41a. This connection and disconnection causes the supply of power from the power source 2 to the multiple loads 3 to be started and stopped. The first switch 10 is provided, for example, between the power source 2 and the third branch point N3 in the main electric path 41a. The first switch 10 is composed of two switching elements 10a connected in series with each other. Each switching element 10a is, for example, a semiconductor switch (for example, a P-channel MOSFET: metal-oxide-semiconductor field-effect transistor).

[0032] The second switch 11 is provided on the second power supply path 42 (i.e., the power supply path from the power storage device 5 to the first load 31), and is switched on and off under the control of the control circuit 13 to connect and disconnect the second power supply path 42. This connection and disconnection causes the supply of power from the power storage device 5 to the first load 31 to be started and stopped. The second switch 11 is composed of two switching elements 11a connected in series with each other. Each switching element 11a is, for example, a semiconductor switch (for example, a P-channel MOSFET).

[0033] The selection switch 12 is a switch for selecting, from among the plurality of loads 3, a load 3 to which power from the power storage device 5 is to be supplied, in accordance with the control of the control circuit 13. The selection switch 12 includes a plurality of switching elements 12a. Each switching element 12a is provided in a branch path 41b to which a pre-specified load 3 from among the plurality of loads 3 is connected. Each switching element 12a switches on and off in accordance with the control of the control circuit 13, thereby conducting and interrupting the branch path 41b in which the switching element 12a is provided. This conduction and interruption causes the supply of power from the power storage device 5 to the specified load 3 to be started and stopped.

[0034] In this embodiment, the selection switch 12 selects, from the plurality of loads 3, the loads 3 to which power from the power storage device 5 is not to be supplied by controlling the switching element 12a to be turned off. Through this selection, the remaining loads 3 among the plurality of loads 3 are selected as the loads 3 to which power from the power storage device 5 is to be supplied.

[0035] The above-mentioned specified load 3 includes, for example, an electric steering device and its ECU (Electronic Control Unit), and an ECU of a brake device, but does not include a brake device or ADAS (Advanced Driver-Assistance Systems) related equipment.

[0036] In the present embodiment, as an example, the selection switch 12 is controlled as follows. When there is no failure in the power supply 2, all of the switching elements 12a are controlled to be on. As a result, power is supplied from the power supply 2 to all of the specified loads 3. Furthermore, when the vehicle 9 is in autonomous driving mode when the power supply 2 fails, all of the switching elements 12a are controlled to be on. As a result, power is supplied from the power storage device 5 to all of the specified loads 3. As a result, when the vehicle 9 is in autonomous driving mode when the power supply 2 fails, power is supplied from the power storage device 5 to all of the loads 3 related to the autonomous driving. Furthermore, when the vehicle 9 is not in autonomous driving mode when the power supply 2 fails, all of the switching elements 12a are controlled to be off. As a result, the supply of power from the power storage device 5 to the specified loads 3 is stopped. As a result, for example, power is supplied from the power storage device 5 to loads that are related to braking of the vehicle 9 and that utilize the driver's power (e.g., a brake device), while power is not supplied from the power storage device 5 to loads that are not related to braking of the vehicle 9 and that do not utilize the driver's power (e.g., an electric steering device and its ECU, and an ECU for the brake device).

[0037] (1-2-7. Control circuit) The control circuit 13 determines whether a failure has occurred in the power supply 2, for example, by monitoring the output voltage of the power supply 2. Furthermore, the control circuit 13 controls the first voltage conversion circuit 6, the second voltage conversion circuit 7, the first switch 10, the second switch 11, and the selection switch 12 depending on whether a failure has occurred in the power supply 2. Details of the operation of the control circuit 13 will be described later in the operation explanation.

[0038] The control circuit 13 is configured, for example, by a microcomputer having a processor and a memory. That is, the control circuit 13 is realized by a computer system having a processor and a memory. The processor executes an appropriate program, causing the computer system to function as the control circuit 13. The program may be pre-recorded in the memory, or may be provided via a telecommunications line such as the Internet, or recorded on a non-transitory recording medium such as a memory card.

[0039] (1-3. Operation explanation) The main operations of the backup power supply system 1 will be described with reference to FIGS.

[0040] As shown in FIG. 1, when there is no failure in the power supply 2, the control circuit 13 controls the first switch 10 (i.e., the two switching elements 10a) to be on and the second switch 11 (i.e., the two switching elements) to be off, thereby stopping the first voltage conversion circuit 6. As a result, the output power of the power supply 2 is supplied to the first power supply line 41 (i.e., the main power supply line 41 and a plurality of branch paths 41b) to be supplied to a plurality of loads 3 (i.e., a first load 31 and a second load 32).

[0041] Furthermore, if no failure has occurred in the power supply 2, the control circuit 13 activates the second voltage conversion circuit 7. As a result, the output power of the power supply 2 is supplied to the power storage device 5 from the third branch point of the first power supply line 41 through the fourth power supply line 44 (i.e., through the second voltage conversion circuit 7). As a result, the power storage device 5 is charged. As a result of this charging, the voltage of the power storage device 5 when fully charged becomes higher than the output voltage of the power supply 2.

[0042] Furthermore, if a failure occurs in power supply 2, control circuit 13 stops second voltage conversion circuit 7. As a result, charging of power storage device 5 by second voltage conversion circuit 7 is stopped.

[0043] Furthermore, if a failure occurs in the power supply 2, the control circuit 13 controls the first switch 10 (i.e., the two switching elements 10a) to be turned off and the second switch 11 (i.e., the two switching elements 11a) to be turned on, thereby activating (starting) the first voltage conversion circuit 6. As a result, the output power of the power storage device 5 is output to the first branch point N1 of the first power supply path 41 through the second power supply path 42 and is supplied to the multiple loads 3 (particularly the first load 31) through the first power supply path 41. At this time, because the voltage of the power storage device 5 when fully charged is higher than the output voltage of the power supply 2, a sufficiently large operating current is supplied to the first load 31 (i.e., the power system load) without boosting the output voltage of the power storage device 5.

[0044] In parallel with this supply, the output power of the power storage device 5 is output to the second branch point N2 of the first power supply line 41 through the third power supply line 43, and is also supplied to the second load 32 through the first power supply line 41. At this time, until the first voltage conversion circuit 6 is started up (i.e., from the start of start-up to the completion of start-up (for example, 100 ms (milliseconds))), the output power of the power storage device 5 that passes through the third power supply line 43 is output to the second branch point N2 through the first bypass path 81 (i.e., without passing through the first voltage conversion circuit 6). In other words, until the first voltage conversion circuit 6 is started up, the output voltage of the first voltage conversion circuit 6 has not been sufficiently boosted and is lower than the output voltage of the power storage device 5, so the output voltage of the power storage device 5 is output to the second branch point N2 through the first bypass path 81.

[0045] In this way, until the first voltage conversion circuit 6 is started up, the output power of the power storage device 5 is not transformed (boosted) by the first voltage conversion circuit 6. However, because the voltage of the power storage device 5 when fully charged is higher than the output voltage of the power source 2, the output voltage of the power storage device 5 output to the second branch point N2 is maintained at or above the minimum guaranteed operating voltage of the second load 32. This makes it possible to prevent the output voltage from the power storage device 5 to the second load 32 from being interrupted until the first voltage conversion circuit 6 is started up.

[0046] In this embodiment, the second power supply line 42 and a partial electric path in the first power supply line 41 between the first branch point N1 and the second branch point N2 form a second bypass path 82. Until the first voltage conversion circuit 6 is started up, the output power of the power storage device 5 is also output to the first branch point N1 via the second bypass path 82. Therefore, the second bypass path 82 also makes it possible to prevent the output voltage from the power storage device 5 to the second load 32 from being interrupted until the first voltage conversion circuit 6 is started up.

[0047] After the first voltage conversion circuit 6 is started (i.e., after the start-up is completed), the output power of the power storage device 5 that passes through the third power supply path 43 is output to the second branch point N2 via the first voltage conversion circuit 6. That is, after the first voltage conversion circuit 6 is started, the output voltage of the first voltage conversion circuit 6 is sufficiently boosted and becomes higher than the output voltage of the power storage device 5, so the output voltage of the power storage device 5 does not pass through the first bypass path 81, is boosted by the first voltage conversion circuit 6, and is output to the second branch point N2.

[0048] In this way, after the first voltage conversion circuit 6 is started, the output voltage of the storage device 5 is maintained at a constant voltage equal to or higher than the minimum guaranteed operating voltage of the second load 32 by passing through the first voltage conversion circuit 6, even if the output voltage of the storage device 5 drops.

[0049] Furthermore, when power is supplied from the storage device 5 to the second load 32 via the third power supply line 43 or the bypass paths 81, 82, the diode 9 prevents the power supplied to the second load 32 from flowing back through the first power supply line 41 and being taken by the first load 31.

[0050] In this embodiment, for a certain period of time (e.g., 7 seconds) after a failure of the power supply 2, the load 3 selected by the selection switch 12 is continuously supplied with power necessary for the operation of the load 3. More specifically, an operating current equal to or greater than a certain current value (e.g., an operating current equal to or greater than 16 A) is supplied to the first load 31, and a constant voltage (e.g., 12 V) equal to or greater than a minimum guaranteed operating voltage Vt (e.g., 11.5 V) is supplied to the second load 32. FIG. 3 shows an example of the voltage V1 and current I1 output from the power storage device 5 to the first load 31 via the second power supply line 42 over time when a failure of the power supply 2 occurs. Vs in FIG. 3 is the minimum guaranteed operating voltage of the first load 31 (e.g., 9.5 V). FIG. 4 shows an example of the voltage V2 and current I2 output from the power storage device 5 to the second load 32 via the third power supply line 43 over time when a failure of the power supply 2 occurs. Vt in FIG. 4 is the minimum guaranteed operating voltage of the first load 31 (e.g., 11.5 V). 3 and 4, the time when the power supply 2 fails is set as time t=0.

[0051] As shown in FIG. 3, current I1 increases from 16 A to 30 A and remains at 30 A for a certain period of time (e.g., 7 seconds). That is, current I1 remains at a current of 16 A or more, which is necessary for the operation of first load 31, for a certain period of time. Voltage V1 gradually decreases from 15 V over time, but remains at a voltage equal to or greater than the minimum operating voltage Vs of first load 31 for a certain period of time (e.g., 7 seconds). As shown in FIG. 4, current I2 remains at a current (e.g., 2.5 A) necessary for the operation of second load 32 for a certain period of time (e.g., 7 seconds). Voltage V2 remains at a voltage (12 V) equal to or greater than the minimum operating voltage Vt of second load 32 for a certain period of time (e.g., 7 seconds).

[0052] In this way, for a certain period of time (e.g., 7 seconds) after the occurrence of a failure in the power supply 2, the first load 31 is continuously supplied with the operating current required for the operation of the first load 31, and the second load 32 is continuously supplied with a certain voltage equal to or higher than the minimum guaranteed operating voltage Vt. The certain period of time is the time required for the vehicle 9 traveling at a predetermined speed (e.g., 60 km / h) to come to a stable stop. This allows the vehicle 9 to come to a stable stop, for example, if a defect occurs in the power supply 2 while the vehicle 9 is traveling at the predetermined speed.

[0053] (1-4. Main Effects) As described above, the backup power supply system 1 according to this embodiment is a system that supplies power from the power storage device 5 to multiple loads 3 when the power supply 2 fails. The backup power supply system 1 includes a first voltage conversion circuit 6. The first voltage conversion circuit 6 transforms the output voltage of the power storage device 5. The multiple loads 3 include a first load 31 and a second load 32. Power from the power storage device 5 is supplied to the first load 31 without passing through the first voltage conversion circuit 6. Power from the power storage device 5 is supplied to the second load 32 via the first voltage conversion circuit 6. With this configuration, the first voltage conversion circuit 6 performs voltage conversion only for some of the multiple loads 3 (the second load 32). This allows the first voltage conversion circuit 6 to be made smaller than when voltage conversion is performed for multiple loads 3. As a result, the cost of the first voltage conversion circuit can be reduced.

[0054] (2. Modifications) Next, modified examples of the above embodiment will be described. The modified examples described below can be applied in appropriate combinations. In the modified examples described below, differences from the embodiment will be mainly described, and the same parts as the embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0055] (2-1. Variation 1) In the above-described embodiment, the power storage device 5 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 a material similar to that of an EDLC (for example, activated carbon), and the negative electrode is formed of a material similar to that of a LIB (for example, a carbon material such as graphite).

[0056] The power storage device 5 is not limited to an electric double layer capacitor, and may be, for example, an electrochemical device having the following configuration. The electrochemical device 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 containing 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 containing a negative electrode active material. The negative electrode active material is, for example, a substance that undergoes an oxidation-reduction reaction involving the absorption and desorption of lithium ions, 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.

[0057] (2-2. Variation 2) In the above embodiment, one first voltage conversion circuit 6 is provided, but as shown in FIG. 5, multiple first voltage conversion circuits 6 may be provided. In the above embodiment, the first voltage conversion circuit 6, the third power supply path 43, the diode 9, the first bypass path 81, and the diode 811 form one set. Therefore, in this modification, multiple sets are provided. Also, in this modification, the second load 32 is divided into multiple load groups corresponding to the multiple first voltage conversion circuits 6. The multiple load groups have different minimum operating voltages.

[0058] The example of FIG. 5 illustrates a case where two first voltage conversion circuits 6 are provided, i.e., two sets are provided. In this case, the plurality of load groups are divided into two load groups. These two load groups are distinguished as load group 32a and load group 32b. Furthermore, the two sets are distinguished as set G1 and set G2.

[0059] The third power supply line 43 of each of the groups G1 and G2 is connected between the input / output unit of the power storage device 5 and two branch points N2a and N2b of the first power supply line 41. The branch point N2a is a branch point located between the first load 31 and the load group 32a on the first power supply line 41. The branch point N2b is a branch point located between the two load groups 32a and 32b on the first power supply line 41. The diode 9 of the group G1 is provided in the main electric circuit 41a of the first power supply line 41 between the first load 31 and the branch point N2a. The diode 9 of the group G2 is provided in the main electric circuit 41a of the first power supply line 41 between the load group 32a and the branch point N2a. The first voltage conversion circuit 6 of each group G1, G2 corresponds to two load groups 32a, 32b, respectively, and transforms the output voltage of the storage device 5, maintains it at a constant voltage equal to or higher than the minimum guaranteed operating voltage of the corresponding load group, and outputs it to the corresponding load group.

[0060] According to this modification, since a plurality of first voltage conversion circuits 6 are provided, each first voltage conversion circuit can be made smaller, and the entire plurality of first voltage conversion circuits 6 can also be made smaller. As a result, the cost of the first voltage conversion circuits 6 can be further reduced.

[0061] (2-3. Other Modifications) In the above embodiment, the diode 811 is provided in the first bypass path 81, but instead of the diode 811, a series regulator may be provided.

[0062] In the above embodiment, the first load 31 and the second load 32 each include a plurality of loads (load groups), but the first load 31 and the second load 32 may each include a single load. Also, at least one of the first load 31 and the second load 32 may be a load group consisting of a plurality of loads.

[0063] In the above embodiment, the first load 31 satisfies both the first condition and the second condition compared to the second load 32, but it is sufficient if the first load 31 satisfies at least one of the first condition and the second condition. The first condition is that the power consumption is large (i.e., the operating current is large), and the second condition is that the minimum guaranteed operating voltage is small.

[0064] (3. Summary) From the above embodiments and modifications, the present disclosure includes the following aspects.

[0065] A backup power supply system (1) according to a first aspect supplies power from a power storage device (5) to a plurality of loads (3) when a power source (2) fails. The backup power supply system (1) includes a voltage conversion circuit (6) that transforms an output voltage of the power storage device (5). The plurality of loads (3) include a first load (31) and a second load (32). The backup power supply system (1) supplies power from the power storage device (5) to the first load (31) without passing through the voltage conversion circuit (6), and supplies power from the power storage device (5) to the second load (32) via the voltage conversion circuit (6).

[0066] According to this configuration, the voltage conversion circuit (6) performs voltage conversion only for a portion of the loads (3) (the second load (32)), and therefore the voltage conversion circuit (6) can be made smaller, thereby reducing the cost of the voltage conversion circuit.

[0067] In the backup power supply system (1) according to the second aspect, in the first aspect, the first load (31) satisfies at least one of a first condition that the first load (31) consumes more power than the second load (32) and a second condition that the first load (31) has a lower minimum operating voltage.

[0068] According to this configuration, power can be supplied from the power storage device (5) to a load among the plurality of loads (3) that satisfies at least one of the first condition and the second condition without going through the voltage conversion circuit (6).

[0069] The backup power supply system (1) according to a third aspect is the backup power supply system (1) according to the first or second aspect, further comprising a bypass path (8) connected in parallel to the voltage conversion circuit (6).

[0070] This configuration can prevent the output voltage from the electricity storage device (5) to the second load (32) from being interrupted until the voltage conversion circuit (6) is started up (i.e., from the start of start-up to the completion of start-up).

[0071] In the backup power supply system (1) according to the fourth aspect, in the third aspect, the bypass path (8) includes a first bypass path (81) separated from the power supply path from the power storage device (5) to the first load (31).

[0072] According to this configuration, even if a circuit (e.g., a switch) that may cause a momentary voltage interruption is provided in the power supply path from the electricity storage device (5) to the first load (31), the bypass path (8) can suppress the influence of the momentary voltage interruption.

[0073] In the backup power supply system (1) according to the fifth aspect, in the third or fourth aspect, the bypass path (8) includes a second bypass path (82) using a power supply path from the power storage device (5) to the first load (31).

[0074] According to this configuration, the bypass path (8) can be configured by utilizing the power supply path (ie, the existing power supply path) from the power storage device (5) to the first load (31).

[0075] In the backup power supply system (1) according to a sixth aspect, in any one of the third to fifth aspects, the bypass path (8) includes a diode (811).

[0076] This configuration can prevent a current from flowing backward in the bypass path (8).

[0077] The backup power supply system (1) according to a seventh aspect is any one of the third to fifth aspects, and further includes a charging circuit (7) that charges the power storage device (5).

[0078] According to this configuration, the charging circuit (7) can control the voltage (charging voltage) when the electricity storage device (5) is being charged, and as a result, the voltage when the electricity storage device (5) is fully charged can be controlled.

[0079] The backup power supply system (1) according to an eighth aspect is any one of the first to seventh aspects, further comprising a switch (11) that connects and disconnects a power supply path from the power storage device (5) to the first load (31).

[0080] According to this configuration, the switch (11) can selectively switch between supplying and cutting off the power from the electricity storage device (5) to the first load (31).

[0081] A backup power supply system (1) according to a ninth aspect is any one of the first to eighth aspects, wherein at least one of the first load (31) and the second load (32) includes a load group consisting of a plurality of loads (3), and further includes a selection switch (12) that selects a load from the load group to which power from the power storage device (5) is to be supplied.

[0082] According to this configuration, the load (3) to which the power from the power storage device (5) is supplied can be selected from the load group by the selection switch (12).

[0083] The backup power supply system (1) according to a tenth aspect is any one of the first to ninth aspects, wherein the power storage device (5) is a capacitor.

[0084] According to this configuration, a capacitor-type electricity storage device (for example, an electric double layer capacitor) can be used as the electricity storage device (5).

[0085] A backup power supply system (1) according to an eleventh aspect is any one of the first to tenth aspects, wherein the power storage device (5) is charged by the power source (2). The voltage of the power storage device (5) when fully charged is higher than the output voltage of the power source (2).

[0086] According to this configuration, a sufficiently large current can be supplied from the electricity storage device (5) to the first load (31) without passing through a voltage conversion circuit.

[0087] A backup power supply system (1) according to a twelfth aspect is any one of the first to eleventh aspects, and further includes a power storage device (5).

[0088] According to this configuration, it is possible to provide a backup power supply system (1) including the power storage device (5).

[0089] A mobile object (9) according to a thirteenth aspect includes the backup power supply system (1) according to the twelfth aspect and a mobile object main body (91).

[0090] According to this configuration, a mobile object (9) equipped with the backup power supply system (1) can be provided. [Explanation of symbols]

[0091] 1. Backup Power System 2 power supply 3. Load 5. Energy storage device 6 First voltage conversion circuit (voltage conversion circuit) 7 Second voltage conversion circuit (charging circuit) 8. Bypass Route 11 Second switch (switch) 12 Selector switch 31 1st load 32 2nd load 81 First Bypass Route 82 Second Bypass Route

Claims

1. A backup power supply system that supplies power from a power storage device to a plurality of loads when a power supply fails, a voltage conversion circuit that transforms an output voltage of the power storage device; the plurality of loads includes a first load and a second load; supplying electric power from the power storage device to the first load without passing through the voltage conversion circuit; supplying the power from the power storage device to the second load via the voltage conversion circuit; the voltage conversion circuit does not supply power to the second load when the power supply is normal, and supplies power to the second load when the power supply fails. Backup power system.

2. The first load satisfies at least one of a first condition that the first load has a higher power consumption and a second condition that the first load has a lower minimum operating voltage than the second load.

10. The backup power system of claim 1.

3. Further comprising a bypass path connected in parallel to the voltage conversion circuit.

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

4. The bypass path includes a first bypass path separated from a power supply path from the power storage device to the first load.

4. The backup power system of claim 3.

5. The bypass path includes a second bypass path using a power supply path from the power storage device to the first load.

5. The backup power supply system according to claim 3 or 4.

6. the bypass path includes a diode. The backup power supply system according to any one of claims 3 to 5.

7. Further comprising a charging circuit for charging the power storage device. The backup power supply system according to any one of claims 3 to 5.

8. 8. The backup power supply system according to claim 1, further comprising a switch that connects and disconnects a power supply path from the power storage device to the first load.

9. At least one of the first load and the second load includes a load group consisting of a plurality of loads, The power supply device further includes a selection switch that selects a load to which power from the power storage device is to be supplied from the group of loads. The backup power supply system according to any one of claims 1 to 8.

10. The power storage device is a capacitor. The backup power supply system according to any one of claims 1 to 9.

11. The power storage device is charged by the power source, A voltage of the power storage device when fully charged is higher than an output voltage of the power source. The backup power supply system according to any one of claims 1 to 10.

12. The power storage device is provided. A backup power supply system according to any one of claims 1 to 11.

13. A backup power system according to claim 12; A moving body; Mobile body.

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