Backup Power Supply

Abstract

To provide a backup power supply device which effectively utilizes electric charge accumulated in a capacitor.SOLUTION: In a case where a main battery 2 is normal during ignition-on, a control unit 35 controls ON / OFF of a charging circuit 32 to charge a capacitor 31 from the main battery 2 in such a manner that a voltage of the capacitor 31 is fixed at a target voltage and controls a discharging circuit 33 to stop discharge from the capacitor 31 to a first electronic apparatus 4. In a case where abnormality occurs in the main battery 2 during the ignition-on, the control unit turns off the charging circuit 32 to stop charging the capacitor 31 from the main battery 2 and turns on the discharging circuit 33 to perform the discharge from the capacitor 31 to the first electronic apparatus 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Automobiles generally have an on-board battery as a main power source. They also have an alternator (generator) for charging the on-board battery. DC power is supplied from the main power source to a large number of different electronic devices mounted in various parts of the vehicle. Each electronic device in the vehicle is used to perform various functions, such as running, steering, stopping, door opening and closing, lighting, and communication, either constantly or as needed, and requires a supply of power.

[0003] On the other hand, if the vehicle battery, alternator, wiring harness, or other components are damaged due to, for example, a traffic accident, the power from the main power source is cut off, and the main power source is no longer able to supply power to each electronic device. However, in order to prevent the situation from worsening, it is desirable to continue supplying power to important electronic devices even when the power from the main power source is cut off. For this reason, a backup power source that can replace the main power source is required.

[0004] As this backup power source, it has been proposed to use an electric double layer capacitor or a lithium ion capacitor (Patent Document 1). This electric double layer capacitor is prone to degradation if an electric charge is allowed to remain stored in it for a long period of time. Lithium ion capacitors also tend to deteriorate if left fully charged for a long period of time.

[0005] To cope with this, it has been considered to discharge the electric double layer capacitor or lithium ion capacitor through a discharge resistor when the ignition is turned off. However, this has the problem that the charge stored in these capacitors is discharged unnecessarily. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-182317 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a backup power supply device that effectively utilizes the charge stored in a capacitor. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the backup power supply device according to the present invention is characterized as follows [1]. [1] a capacitor provided as a backup for a main power supply that supplies power to the first electronic device; a charging circuit provided between the main power supply and the capacitor, for turning on and off charging the capacitor from the main power supply; a connection point between the charging circuit and the capacitor, and the first electronic device; a discharge circuit that turns on and off discharge from the capacitor to the first electronic device; a control unit that, when the main power supply is normal while an ignition is on, controls on and off of the charging circuit to charge the capacitor from the main power supply so that the voltage of the capacitor is constant at a target voltage, and turns off the discharging circuit to stop discharging from the capacitor to the first electronic device, and, when an abnormality occurs in the main power supply while the ignition is on, turns off the charging circuit to stop charging from the main power supply to the capacitor, and turns on the discharging circuit to discharge from the capacitor to the first electronic device. 1. A backup power supply device, comprising: A connection point between the discharge circuit and the first electronic device and A first switch is provided between the first electronic device and the second electronic device, the control unit turns on the discharge circuit and the first switch and turns off the charge circuit after an ignition is turned off, thereby discharging the capacitor to the second electronic device and stopping charging the capacitor from the main power source. It is a backup power supply. Effect of the Invention

[0009] According to the present invention, it is possible to provide a backup power supply device that effectively utilizes the charge stored in the capacitor.

[0010] The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following description of the preferred embodiment of the present invention (hereinafter, referred to as "embodiment") with reference to the accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a circuit diagram showing an embodiment of a power supply system incorporating a backup power supply device of the present invention in a first embodiment. [Diagram 2] FIG. 2 is a table showing the states of the charging circuit, the discharging circuit, and the first to third switches shown in FIG. [Diagram 3] FIG. 3 is a circuit diagram showing an embodiment of a power supply system incorporating a backup power supply device of the present invention in the second embodiment. [Figure 4] FIG. 4 is a table showing the states of the charging circuit, the discharging circuit, the first switch, and the second switch shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0013] (First embodiment) First, a power supply system 1 incorporating a backup power supply device 3 of the first embodiment will be described with reference to Fig. 1. The power supply system 1 of the present embodiment is mounted on an automobile. As shown in Fig. 1, the power supply system 1 of the first embodiment includes a main battery 2 as a main power source, a backup power supply device 3 provided for backing up the main battery 2, a first electronic device 4 that receives power supply from the main battery 2 and the backup power supply device 3, and a second electronic device 5 that is different from the first electronic device 4.

[0014] The main battery 2 supplies power to the first electronic device 4 and the second electronic device 5. The first electronic device 4 is a device that receives power when the ignition is on and operates, and does not need to operate when the ignition is off and the power supply is cut off. The first electronic device 4 is an important device to which power supply should be continued even if an abnormality occurs in the main battery 2 due to an accident or the like and the main battery 2 is unable to supply power to the first electronic device 4.

[0015] The second electronic device 5 is composed of a communication device for communicating with a terminal such as a smartphone, a lighting device, an air purifier, etc., and is a device that needs to be supplied with power to operate not only while the ignition is on, but also for a certain period of time after the ignition is turned off.

[0016] Next, the backup power supply device 3 will be described. The backup power supply device 3 has an electric double layer capacitor 31 as a capacitor, a charging circuit 32, a discharging circuit 33, a conductive path R1, a conductive path R2, a discharging resistor 34, first to third switches S1 to S3, and a control unit 35. The electric double layer capacitor 31 is provided as a backup for the main battery 2. The electric double layer capacitor 31 deteriorates if a state in which electric charge is stored continues. For this reason, when the ignition is on, the electric double layer capacitor 31 is sufficiently charged so that the voltage becomes a target voltage in preparation for the occurrence of an abnormality in the main battery 2, and when the ignition is off, the electric double layer capacitor 31 is discharged until the voltage becomes 0 to prevent deterioration.

[0017] The charging circuit 32 is provided between the positive electrode of the main battery 2 and one end of the electric double layer capacitor 31. The negative electrode of the main battery 2 and the other end of the electric double layer capacitor 31 are connected to the ground. The charging circuit 32 can turn on and off the charging (power supply) from the main battery 2 to the electric double layer capacitor 31. For example, when the voltage of the main battery 2 is higher or lower than that of the electric double layer capacitor 31, the charging circuit 32 has a DC (Direct current) / DC converter that steps down or steps up the power supply voltage of the main battery 2 and supplies it to the electric double layer capacitor 31, and a switch (neither of which is shown) that turns on and off the power supply from the main battery 2 to the DC / DC converter. Also, when the voltages of the main battery 2 and the electric double layer capacitor 31 are approximately equal, the charging circuit 32 has only a switch (not shown). By turning on and off the switch of the charging circuit 32, the charging from the main battery 2 to the electric double layer capacitor 31 can be turned on and off.

[0018] The discharge circuit 33 is provided between one end of the electric double layer capacitor 31 and the first electronic device 4. The discharge circuit 33 can turn on and off the discharge (power supply) from the electric double layer capacitor 31 to the first electronic device 4. For example, when the voltage supplied to the first electronic device 4 is higher or lower than the voltage of the electric double layer capacitor 31, the discharge circuit 33 has a DC / DC converter that steps down or steps up the voltage of the electric double layer capacitor 31 and supplies it to the first electronic device 4, and a switch (neither of which is shown) that turns on and off the power supply from the electric double layer capacitor 31 to the DC / DC converter. Also, when the voltages of the electric double layer capacitor 31 and the first electronic device 4 are approximately equal, the discharge circuit 33 has only a switch. By turning on and off the switch of the discharge circuit 33, the discharge from the electric double layer capacitor 31 to the first electronic device 4 can be turned on and off. The above-mentioned charging circuit 32 and discharge circuit 33 are controlled by a control unit 35 described later.

[0019] The conduction path R1 is connected to the first electronic device 4 and the positive electrode of the main battery 2, and bypasses the charging circuit 32 and the discharging circuit 33. The conduction path R2 is connected to the second electronic device 5 and the positive electrode of the main battery 2, and bypasses the charging circuit 32 and the discharging circuit 33. The discharge resistor 34 is connected in parallel with the electric double layer capacitor 31 between the charging circuit 32 and the discharging circuit 33. One end of the discharge resistor 34 is connected to one end of the electric double layer capacitor 31 via a third switch S3 described later, and the other end is connected to ground.

[0020] The first switch S1 is provided between the second electronic device 5 and the electric double layer capacitor 31. In this embodiment, the first switch S1 is provided closer to the second electronic device 5 than the connection point between the discharge circuit 33 and the first electronic device 4. When the first switch S1 is turned on, discharging from the electric double layer capacitor 31 to the second electronic device 5 becomes possible, and when the first switch S1 is turned off, discharging from the electric double layer capacitor 31 to the second electronic device 5 is blocked.

[0021] The second switch S2 is provided on the conduction path R2 that connects the second electronic device 5 and the main battery 2, and is connected in parallel to the first switch S1. When the second switch S2 is turned on, power can be supplied from the main battery 2 to the second electronic device 5, and when the second switch S2 is turned off, power supply from the main battery 2 to the second electronic device 5 is cut off.

[0022] The third switch S3 is provided on a discharge path from the electric double layer capacitor 31 to the discharge resistor 34. In this embodiment, the third switch S3 is connected between one end of the electric double layer capacitor 31 and the discharge resistor 34. To explain in detail, the electric double layer capacitor 31, the discharge resistor 34 connected in series, and the third switch S3 are connected in parallel between the connection point of the charging circuit 32 and the discharging circuit 33 and the ground. When the third switch S3 is turned on, the electric double layer capacitor 31 is discharged by the discharge resistor 34, and when the third switch S3 is turned off, the discharge from the electric double layer capacitor 31 to the discharge resistor 34 is cut off. The first to third switches S1 to S3 are controlled to be turned on and off by a control unit 35 described later.

[0023] The control unit 35 is connected to the above-mentioned charging circuit 32, discharging circuit 33, and first to third switches S1 to S3, and controls the on / off of the switches (not shown) of the charging circuit 32 and discharging circuit 33, and the first to third switches S1 to S3. The control unit 35 has, for example, a microcomputer (not shown). The microcomputer has a memory that stores a program, and a CPU (Central Processing Unit) that operates according to the program.

[0024] Next, the operation of the power supply system 1 having the above-mentioned configuration will be described with reference to Fig. 2. In the power supply system 1 of this embodiment, the user can set in advance whether the second electronic device 5 is to be used for a certain period of time even after the ignition is turned off, or not to be used at all. For this setting, for example, an input unit of a navigation device or communication with a smartphone can be used. The setting contents can be stored in the memory of the control unit 35. That is, the control unit 35 also functions as a storage unit.

[0025] Immediately after the ignition is turned off, the control unit 35 determines whether the second electronic device 5 is set to be used for a certain period of time after the ignition is turned off. If the second electronic device 5 is set to be used for a certain period of time after the ignition is turned off, the control unit 35 turns on the switch of the discharging circuit 33 and the first switch S1, and turns off the switch of the charging circuit 32 and the second and third switches S2 and S3, as shown in FIG. 2(A).

[0026] As a result, charging of the electric double layer capacitor 31 from the main battery 2 and power supply to the second electronic device 5 are cut off, and the electric double layer capacitor 31 is discharged by the second electronic device 5. When the ignition is off, the switch built into the first electronic device 4 is turned off, so that discharging from the electric double layer capacitor 31 to the first electronic device 4 is not performed.

[0027] On the other hand, if the second electronic device 5 is set not to be used after the ignition is turned off, the control unit 35 turns on the third switch S3 and turns off the switches of the charging circuit 32 and the discharging circuit 33, and the first and second switches S1 and S2, as shown in Fig. 2(B). This cuts off charging from the main battery 2 to the electric double layer capacitor 31. Also, discharging (power supply) from the main battery 2 and the electric double layer capacitor 31 to the second electronic device 5 is cut off, and no power is supplied to the second electronic device 5, so it is not used. Also, the electric double layer capacitor 31 is discharged by the discharge resistor 34.

[0028] The control unit 35 detects the voltage of the electric double layer capacitor 31, and when it determines that the electric double layer capacitor 31 has been discharged by the second electronic device 5 or the discharge resistor 34 and the charge has become zero (i.e., the discharge has ended), it turns off the switches of the charging circuit 32 and the discharging circuit 33 and the first to third switches S1 to S3, as shown in Fig. 2(C). In other words, if the second electronic device 5 is set to be used after the ignition is turned off, power is supplied to the second electronic device 5 until the charge of the electric double layer capacitor 31 becomes zero.

[0029] Furthermore, when the ignition is on and the main battery 2 is not experiencing any abnormality during normal operation, the control unit 35 repeatedly switches the charging circuit 32 on and off as shown in Fig. 2(D). To explain in more detail, the control unit 35 detects the voltage of the electric double layer capacitor 31, and if the detected voltage reaches the target voltage, turns off the charging circuit 32 to cut off charging from the main battery 2 to the electric double layer capacitor 31. When natural discharge occurs and the detected voltage of the electric double layer capacitor 31 falls below the target voltage, the control unit 35 turns on the charging circuit 32 to charge the electric double layer capacitor 31 from the main battery 2.

[0030] 2(D), the control unit 35 turns on the second switch S2 and turns off the switch of the discharge circuit 33, the first switch S1, and the second switch S2. As a result, the second electronic device 5 operates by receiving power supply from the main battery 2, and discharging from the electric double layer capacitor 31 to the discharge resistor 34 and the second electronic device 5 is cut off. Note that when the ignition is on, the switch built into the first electronic device 4 is on, so power is supplied from the main battery 2 to the first electronic device 4 via the conductive path R1.

[0031] Furthermore, when the ignition is on and an abnormality occurs in the main battery 2, the control unit 35 turns on the switch of the discharge circuit 33 and turns off the switch of the charging circuit 32 and the first to third switches S1 to S3, as shown in Fig. 2(E). This allows power to be supplied from the electric double layer capacitor 31 to the first electronic device 4, and the power supply to the first electronic device 4 can be continued even after an abnormality occurs in the main battery 2. Also, charging from the main battery 2 to the electric double layer capacitor 31 and power supply from the main battery 2 and the electric double layer capacitor 31 to the second electronic device 5 are cut off.

[0032] According to the above-described first embodiment, after the ignition is turned off, the control unit 35 turns on the discharge circuit 33 and the first switch S1 and turns off the charge circuit 32, thereby discharging the electric double layer capacitor 31 to the second electronic device 5 and stopping charging the electric double layer capacitor 31 from the main battery 2. This makes it possible to discharge the electric double layer capacitor 31 to prevent deterioration after the ignition is turned off, and further makes it possible to effectively utilize the discharge energy as a power source for the second electronic device 5.

[0033] Furthermore, according to the above-described first embodiment, during normal operation when the main battery 2 is normal while the ignition is on, the control unit 35 can turn on the second switch S2 to supply power from the main battery 2 to the second electronic device 5. Furthermore, during abnormal operation when an abnormality occurs in the main battery 2 while the ignition is on and after the ignition is off, the control unit 35 turns off the second switch S2 to cut off the power supply from the main battery 2 to the second electronic device 5, and does not impede the discharge from the electric double layer capacitor 31 to the second electronic device 5.

[0034] Furthermore, according to the above-described first embodiment, even after the charge on the electric double layer capacitor 31 becomes zero after the ignition is turned off, the control unit 35 turns off the second switch S2 to cut off the power supply from the main battery 2 to the second electronic device 5. This allows the second electronic device 5 to be driven only until the charge on the electric double layer capacitor 31 becomes zero after the ignition is turned off.

[0035] Furthermore, according to the above-described first embodiment, when the second electronic device 5 is set to be used, the control unit 35 turns on the first switch S1 and turns off the third switch S3 after the ignition is turned off, and when the second electronic device 5 is set to not be used, the control unit 35 turns off the second switch S2 and turns on the third switch S3 after the ignition is turned off. This allows the electric double layer capacitor 31 to be discharged even when the second electronic device 5 is set to not be used.

[0036] In the first embodiment described above, the electric double layer capacitor 31 is used as the capacitor, but the present invention is not limited to this. A lithium ion capacitor may be used instead of the electric double layer capacitor 31. In this case, the control unit 35 determines that the discharge is completed when the voltage of the lithium ion capacitor reaches a specified value.

[0037] In the first embodiment described above, the user can set whether to use the second electronic device 5 after the ignition is turned off, but this is not limited to the above. The second electronic device 5 may be always used after the ignition is turned off, and it is not essential to provide the discharge resistor 34 and the third switch S3.

[0038] Second embodiment Next, a power supply system 1 of a second embodiment will be described with reference to Fig. 3. In Fig. 3, parts equivalent to those of the power supply system 1 shown in Fig. 1 already described in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. As shown in Fig. 3, the power supply system 1 of the second embodiment includes a main battery 2, a backup power supply device 3B provided for backing up the main battery 2, and a first electronic device 4 and a second electronic device 5B that receive power supply from the main battery 2 and the backup power supply device 3B.

[0039] The main battery 2 supplies power to the first electronic device 4 and the second electronic device 5B. The first electronic device 4 is the same as in the first embodiment, so a detailed description will be omitted here. The second electronic device 5B is a device that is desired to be operated by continuously supplying power from ignition off to ignition on, such as a clock, a smart key, or a memory.

[0040] Next, the backup power supply device 3B will be described. The backup power supply device 3B has a small lithium ion capacitor 31B as a capacitor, a charging circuit 32B, a discharging circuit 33B, first and second switches S1B and S2B, a conduction path R3, a conduction path R4, and a control unit 35B. The small lithium ion capacitor 31B deteriorates if it continues to be fully charged. For this reason, when the ignition is on, the small lithium ion capacitor 31B is sufficiently charged so that the voltage becomes a target voltage in case an abnormality occurs in the main battery 2, and when the ignition is off, the small lithium ion capacitor is discharged until it reaches a specified value lower than the target voltage in order to prevent deterioration.

[0041] The charging circuit 32B is provided between the positive electrode of the main battery 2 and one end of the small lithium ion capacitor 31B. The negative electrode of the main battery 2 and the other end of the small lithium ion capacitor 31B are connected to the ground. The charging circuit 32B can turn on and off the charging (power supply) from the main battery 2 to the small lithium ion capacitor 31B.

[0042] The discharge circuit 33B is provided between one end of the small lithium ion capacitor 31B and the first electronic device 4. The discharge circuit 33B can turn on and off the discharge (power supply) from the small lithium ion capacitor 31B to the first electronic device 4. The configurations of the charge circuit 32B and the discharge circuit 33B are similar to those of the charge circuit 32 and the discharge circuit 33 in the first embodiment, so detailed description will be omitted here.

[0043] The conductive path R3 is connected to the first electronic device 4 and the positive electrode of the main battery 2, and bypasses the charging circuit 32B and the discharging circuit 33B. The conductive path R4 is connected between the connection point of the discharging circuit 33B and the first electronic device 4, and the second electronic device 5B. The second electronic device 5B is connected between the charging circuit 32B and the main battery 2.

[0044] The first switch S1B is provided between the second electronic device 5B and the small lithium ion capacitor 31B. To explain in detail, a conductive path R4 connects the connection point between the discharge circuit 33B and the first electronic device 4 and the second electronic device 5B. The conductive path R4 connects the small lithium ion capacitor 31B to the second electronic device 5B via the discharge circuit 33B. The first switch S1B is provided on the conductive path R4. When the first switch S1B is turned on, power is supplied from the small lithium ion capacitor 31B to the second electronic device 5B, and when the first switch S1B is turned off, the power supply from the small lithium ion capacitor 31B to the second electronic device 5B is cut off.

[0045] The second switch S2B is provided between the second electronic device 5B and the main battery 2. When the second switch S2B is turned on, power is supplied from the main battery 2 to the first electronic device 4 and the second electronic device 5B, and when the second switch S2B is turned off, the power supply from the main battery 2 to the first electronic device 4 and the second electronic device 5B is cut off.

[0046] Next, the operation of the power supply system 1B configured as described above will be described with reference to Fig. 4. Immediately after the ignition is turned off, the control unit 35B turns on the switch of the discharging circuit 33B and the first switch S1B, and turns off the switch of the charging circuit 32B and the second switch S2B, as shown in Fig. 4(A).

[0047] This cuts off charging of the small lithium ion capacitor 31B from the main battery 2 and power supply to the first electronic device 4 and the second electronic device 5B, and discharges from the small lithium ion capacitor 31B to the second electronic device 5B. Note that when the ignition is off, the switch built into the first electronic device 4 is off, so that discharging from the small lithium ion capacitor 31B to the first electronic device 4 is not performed.

[0048] Thereafter, when the small-sized lithium ion capacitor 31B is discharged and reaches a specified value (discharging is completed), the control unit 35B turns on the second switch S2B and turns off the switches of the charging circuit 32B and the discharging circuit 33B and the first switch S1B, as shown in Fig. 4(B). This allows the second electronic device 5B to continue receiving power from the main battery 2.

[0049] In response to this, when the ignition is on and the main battery 2 is not experiencing any abnormality during normal operation, the control unit 35B repeatedly switches the charging circuit 32B on and off as shown in Fig. 4(C). More specifically, the control unit 35B detects the voltage of the small lithium ion capacitor 31B, and if the detected voltage reaches the target voltage, it turns off the charging circuit 32B to cut off charging of the small lithium ion capacitor 31B from the main battery 2. On the other hand, if natural discharge occurs and the detected voltage falls below the target voltage, the control unit 35B turns on the charging circuit 32B to charge the small lithium ion capacitor 31B from the main battery 2.

[0050] 4(C), the control unit 35B turns on the second switch S2B and turns off the switch of the discharge circuit 33B, the first switch S1B. As a result, the second electronic device 5B operates by receiving power supply from the main battery 2, and discharging from the small lithium ion capacitor 31B to the second electronic device 5B is cut off. Note that when the ignition is on, the switch built into the first electronic device 4 is on, so power is supplied from the main battery 2 to the first electronic device 4.

[0051] Furthermore, when the ignition is on and an abnormality occurs in the main battery 2, the control unit 35B turns on the switch of the discharge circuit 33B and turns off the switch of the charging circuit 32B and the first and second switches S1B and S2B, as shown in Fig. 2(D). This allows power to be supplied from the small lithium ion capacitor 31B to the first electronic device 4, and the power supply to the first electronic device 4 can be continued even after an abnormality occurs in the main battery 2. Also, charging of the small lithium ion capacitor 31B from the main battery 2 and power supply to the second electronic device 5B are cut off.

[0052] According to the above-described second embodiment, after the ignition is turned off, the control unit 35B turns on the discharge circuit 33B and the first switch S1B and turns off the charge circuit 32B to discharge the small lithium ion capacitor 31B to the second electronic device 5B and to stop charging the small lithium ion capacitor 31B from the main battery 2. This makes it possible to discharge the small lithium ion capacitor 31B to prevent deterioration after the ignition is turned off, and further makes it possible to effectively utilize the discharge energy as a power source for the second electronic device 5B.

[0053] Furthermore, according to the second embodiment described above, during normal operation when the main battery 2 is normal while the ignition is on, the control unit 35B can turn on the second switch S2 to supply power from the main battery 2 to the second electronic device 5B. Furthermore, during abnormal operation when an abnormality occurs in the main battery 2 while the ignition is on and after the ignition is off, the control unit 35B turns off the second switch S2 to cut off the power supply from the main battery 2 to the second electronic device 5B, and does not impede the discharge from the small-sized lithium ion capacitor 31B to the second electronic device 5B.

[0054] Furthermore, according to the second embodiment described above, after the voltage of the small lithium ion capacitor 31B reaches a specified value after the ignition is turned off, the control unit 35B turns on the second switch S2B to supply power to the second electronic device 5B from the main battery 2. This makes it possible to drive the second electronic device 5B even after the voltage of the small lithium ion capacitor 31B reaches a specified value after the ignition is turned off.

[0055] According to the second embodiment described above, the small lithium ion capacitor 31B is used as the capacitor, but this is not limited thereto. An electric double layer capacitor may be used instead of the small lithium ion capacitor 31B. In this case, the control unit 35B determines that the discharge has ended when the charge of the electric double layer capacitor becomes zero.

[0056] The present invention is not limited to the above-described embodiment, and can be appropriately modified, improved, etc. In addition, the material, shape, size, number, arrangement location, etc. of each component in the above-described embodiment are arbitrary as long as the present invention can be achieved, and are not limited.

[0057] Here, the features of the embodiments of the backup power supply device according to the present invention described above will be briefly summarized and listed in the following [1] to [6]. [1] a capacitor (31, 31B) provided as a backup for a main power source (2) that supplies power to a first electronic device (4); a charging circuit (32, 32B) provided between the main power supply (2) and the capacitor (31, 31B) for turning on and off charging from the main power supply (2) to the capacitor (31, 31B); a discharge circuit (33, 33B) provided between the capacitor (31, 31B) and the first electronic device (4) for turning on and off discharge from the capacitor (31, 31B) to the first electronic device (4); a control unit (35, 35B) that, when the main power source (2) is normal while an ignition is on, controls on and off of the charging circuit (32, 32B) to charge the capacitor (31, 31B) from the main power source (2) so that the voltage of the capacitor (31, 31B) is constant at a target voltage, and turns off the discharging circuit (33, 33B) to stop discharging from the capacitor (31, 31B) to the first electronic device (4), and, when an abnormality occurs in the main power source (2) while the ignition is on, turns off the charging circuit (32, 32B) to stop charging from the main power source (2) to the capacitor (31, 31B), and turns on the discharging circuit (33, 33B) to discharge from the capacitor (31, 31B) to the first electronic device (4). A backup power supply device (3, 3B), a first switch (S1, S1B) provided between a second electronic device (5, 5B) and the capacitor (31, 31B); the control unit (35, 35B) turns on the discharge circuit (33, 33B) and the first switch (S1, S1B) and turns off the charge circuit (32, 32B) after the ignition is turned off, thereby discharging the capacitor (31, 31B) to the second electronic device (5, 5B) and stopping charging the capacitor (31, 31B) from the main power source (2); Backup power supply (3, 3B).

[0058] According to the above configuration [1], after the ignition is turned off, the capacitor (31, 31B) can be discharged to prevent deterioration, and the discharge energy can be effectively utilized as a power source for the second electronic device (5, 5B).

[0059] [2] In the backup power supply device (3, 3B) according to [1], a second switch (S2, S2B) provided between the second electronic device (5, 5B) and the main power source (2); When the main power supply (2) is normal while the ignition is on, the control unit (35, 35B) turns on the second switch (S2, S2B) to supply power from the main power supply (2) to the second electronic device (5, 5B), and when an abnormality occurs in the main power supply (2) while the ignition is on and after the ignition is off, the control unit (35, 35B) turns off the second switch (S2, S2B) to cut off power from the main power supply (2) to the second electronic device (5, 5B). Backup power supply (3, 3B).

[0060] According to the configuration [2] above, during normal operation when the main power supply (2) is normal while the ignition is on, the control unit (35, 35B) turns on the second switch (S2, S2B) to supply power from the main power supply (2) to the second electronic device (5, 5B). Also, during abnormal operation when an abnormality occurs in the main power supply (2) while the ignition is on and after the ignition is off, the control unit (35, 35B) turns off the second switch (S2, S2B) to cut off the power supply from the main power supply (2) to the second electronic device (5, 5B), and does not impede the discharge from the capacitor (31, 31B) to the second electronic device (5, 5B).

[0061] [3] In the backup power supply device (3) according to [2], The control unit (35) turns off the second switch (S2) and continues to cut off power supply from the main power source (2) to the second electronic device (5) even after the capacitor (31) has reached a discharge completion state after the ignition is turned off. Backup power supply (3).

[0062] According to the configuration [3] above, even after the capacitor (31) reaches the discharge end state after the ignition is turned off, the control unit (35) turns off the second switch (S2) to cut off the power supply from the main power source (2) to the second electronic device (5). This makes it possible to drive the second electronic device (5) only until the capacitor (31) reaches the discharge end state after the ignition is turned off.

[0063] [4] In the backup power supply device (3B) according to [2], After the ignition is turned off and the capacitor (31B) is in a discharge end state, the control unit (35B) turns on the second switch (S2B) to start supplying power from the main power source (2) to the second electronic device (5B). Backup power supply (3B).

[0064] According to the configuration [4] above, after the capacitor (31B) reaches the discharge end state after the ignition is turned off, the control unit (35B) turns on the second switch (S2B) to supply power from the main power source (2) to the second electronic device (5B). This makes it possible to drive the second electronic device (5B) even after the capacitor (31B) reaches the discharge end state after the ignition is turned off.

[0065] [5] In the backup power supply device (3) according to [3], a discharge resistor (34) for discharging the capacitor (31); a third switch (S3) provided between the capacitor (31) and the discharge resistor (34); a storage unit (35) in which a setting as to whether or not to use the second electronic device (5) after the ignition is turned off is stored, When the second electronic device (5) is set to be used, the control unit (35) turns on the first switch (S1) and turns off the third switch (S3) after the ignition is turned off, and when the second electronic device (5) is set not to be used, the control unit (35) turns off the second switch (S2) and turns on the third switch (S3) after the ignition is turned off. Backup power supply (3).

[0066] According to the configuration [5] above, when the second electronic device (5) is set to be used, the control unit (35) turns on the first switch (S1) and turns off the third switch (S3) after the ignition is turned off, and when the second electronic device (5) is set to not be used, the control unit (35) turns off the second switch (S2) and turns on the third switch (S3) after the ignition is turned off. This makes it possible to discharge the capacitor (31) even when the second electronic device (5) is set to not be used.

[0067] [6] In the backup power supply device (3, 3B) according to any one of [1] to [5], The capacitor is composed of either an electric double layer capacitor (31) or a lithium ion capacitor (31B). Backup power supply (3, 3B).

[0068] According to the above configuration [6], the electric double layer capacitor (31) and the lithium ion capacitor (31B) can be effectively utilized. [Explanation of symbols]

[0069] 2 Main battery (main power source) 3. Backup Power Supply 4 1st electronic device 5, 5B 2nd electronic device 31 Electric double layer capacitor (capacitor) 31B Small Lithium Ion Capacitor (Capacitor) 32, 32B charging circuit 33, 33B discharge circuit 34 Discharge resistor 35, 35B Control unit (memory unit) S1, S1B First switch S2, S2B Second switch S3 3rd switch

Claims

1. a capacitor provided as a backup for a main power supply that supplies power to the first electronic device; a charging circuit provided between the main power supply and the capacitor, for turning on and off charging the capacitor from the main power supply; a discharge circuit provided between the first electronic device and a connection point between the charging circuit and the capacitor, the discharge circuit turning on and off discharge from the capacitor to the first electronic device; a control unit that, when the main power supply is normal while an ignition is on, controls on and off of the charging circuit to charge the capacitor from the main power supply so that the voltage of the capacitor is constant at a target voltage, and turns off the discharging circuit to stop discharging from the capacitor to the first electronic device, and, when an abnormality occurs in the main power supply while the ignition is on, turns off the charging circuit to stop charging from the main power supply to the capacitor, and turns on the discharging circuit to discharge from the capacitor to the first electronic device.

1. A backup power supply device, comprising: a first switch provided between a connection point of the discharge circuit and the first electronic device and a second electronic device; the control unit turns on the discharge circuit and the first switch and turns off the charge circuit after an ignition is turned off, thereby discharging the capacitor to the second electronic device and stopping charging the capacitor from the main power source. Backup power supply.

2. 2. The backup power supply device according to claim 1, a second switch provided between the second electronic device and the main power supply; The control unit, when the main power supply is normal while the ignition is on, turns on the second switch to supply power from the main power supply to the second electronic device, and when an abnormality occurs in the main power supply while the ignition is on and after the ignition is turned off, turns off the second switch to cut off power from the main power supply to the second electronic device.

3. 3. The backup power supply device according to claim 2, The control unit turns off the second switch and continues to cut off power supply from the main power supply to the second electronic device even after the capacitor has finished discharging after the ignition is turned off. Backup power supply.

4. 3. The backup power supply device according to claim 2, the control unit turns on the second switch after the capacitor has finished discharging after the ignition is turned off, and starts supplying power from the main power source to the second electronic device. Backup power supply.

5. 4. The backup power supply device according to claim 3, a discharge resistor for discharging the capacitor; a third switch provided between the capacitor and the discharge resistor; a storage unit in which a setting as to whether or not to use the second electronic device after the ignition is turned off is stored, When the second electronic device is set to be used, the control unit turns on the first switch and turns off the third switch after the ignition is turned off, and when the second electronic device is set to not be used, the control unit turns off the second switch and turns on the third switch after the ignition is turned off. Backup power supply.

6. The backup power supply device according to any one of claims 1 to 5, The capacitor is composed of either an electric double layer capacitor or a lithium ion capacitor. Backup power supply.

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