Backup power supply circuit device

Abstract

The purpose of the present disclosure is to effectively utilize the charge residual amounts of a plurality of electricity storage devices while eliminating an imbalance between accumulated charge amounts. The backup power supply circuit device according to the present disclosure is provided with M connection ports (P1, P2) respectively connected to the M connection points between N electricity storage devices (C1-C3). M second switches (SW11, SW12) respectively switch whether or not to connect between the M connection ports (P1, P2) and the loads (31-34). A demultiplexer (M1) has a plurality of output terminals including: a common input terminal (I1) connected to a discharge path (PD11) from a power storage module (40) to a DC-DC converter (10); and M output terminals (O1, O2) connected to the M connection ports (P1, P2). A third switch (SW51) is inserted into the discharge path (PD11) and switches whether or not to connect between the DC-DC converter (10) and the common input terminal (I1).

Description

Backup power circuit device

[0001] The present disclosure relates to a backup power supply circuit device, and more particularly to a backup power supply circuit device that is inserted between, for example, a DC power supply and a load.

[0002] In recent years, with the introduction of driving assistance functions in automobiles, the use of by-wire systems for accelerator, brake, steering, etc. has progressed, and a stable power supply to these on-board devices is required. For this reason, a backup power supply circuit device is provided to supply power to the on-board devices in the event of some kind of failure in the main power supply that supplies power to the on-board devices.

[0003] In addition, data centers and other facilities are equipped with emergency generators in case of momentary power outages caused by lightning strikes, etc., and backup power supply circuit devices are also provided to supply power to data servers for the few minutes until the emergency generators start up.

[0004] Patent Document 1 discloses a DC power supply device using a power transformer, multiple rectifier circuits, and multiple batteries connected in series. This DC power supply device has a path that rectifies the secondary side power of the transformer using a first rectifier circuit and supplies the rectified power directly to a load, and a path that supplies power directly to the load from the series-connected terminals of multiple batteries charged by a second rectifier circuit. The DC power supply device supplies power corresponding to fluctuations in the load voltage by appropriately using the two power supply paths.

[0005] The DC power supply device described in Patent Document 1 achieves high responsiveness by utilizing a path that supplies power directly to a load from a series connection terminal that connects multiple batteries in series. When multiple batteries supply power to a load, a situation occurs in which discharged batteries that supply power to the load and undischarged batteries that do not supply power to the load are mixed, resulting in an imbalance in the charge states of the discharged and undischarged batteries. Furthermore, because the discharged and undischarged batteries are connected in series, the charging current during recharging is limited by the undischarged battery, preventing the discharged battery from being fully charged.

[0006] Japanese Utility Model Application Publication No. 63-029351

[0007] An object of the present disclosure is to provide a backup power supply circuit device that can effectively utilize the remaining charge of a plurality of power storage devices while eliminating the imbalance in the amount of charged charge.

[0008] A backup power supply circuit device according to one aspect of the present disclosure includes a power storage module, a DC-DC converter, a charging path, a first power supply path, a first switch, M connection ports, a discharging path, a demultiplexer, M second power supply paths, M second switches, and a third switch. The power storage module includes a series circuit of N power storage devices (N is an integer greater than or equal to 2) connected in series. The DC-DC converter is connected between a DC power source and the power storage module and is capable of bidirectional voltage step-up / step-down operation. The charging path connects the series circuit of the N power storage devices between output terminals of the DC-DC converter and supplies charging current to the N power storage devices. The first power supply path connects the power storage module and a load. The first switch is inserted in the first power supply path and switches between connection and disconnection between the power storage module and the load. The M connection ports are connected to M connection points (M is an integer greater than or equal to 1 and less than N) out of (N-1) connection points provided between the N power storage devices. The discharge path allows a discharge current to flow from the power storage module via the DCDC converter. The demultiplexer has a common input terminal connected to the discharge path and a plurality of output terminals including M output terminals connected to the M connection ports. The M second power supply paths connect the M connection ports to the load. The M second switches are inserted in the M second power supply paths and respectively switch between connection and non-connection between the M connection ports and the load. The third switch is inserted in the discharge path and switches between connection and non-connection between the DCDC converter and the common input terminal of the demultiplexer.

[0009] FIG. 1 is a schematic circuit diagram showing an example of the configuration of a backup power circuit device according to an embodiment. FIG. 2 is a flowchart showing a discharge process of a power storage module performed by a control unit of the backup power circuit device. FIG. 3 is a graph showing the output voltage versus time elapsed when the control unit of the backup power circuit device performs the discharge process. FIG. 4 is a schematic circuit diagram showing an example of the configuration of a backup power circuit device according to Modification 1. FIG. 5 is a flowchart showing the discharge process of a power storage module performed by a control unit of the backup power circuit device according to Modification 1. FIG. 6 is a graph showing the output voltage versus time elapsed when the control unit of the backup power circuit device according to Modification 1 performs the discharge process. FIG. 7 is a schematic circuit diagram showing an example of the configuration of a backup power circuit device according to Modification 1. FIG. 8 is a schematic circuit diagram showing an example of the configuration of a backup power circuit device according to Modification 2. FIG. 9 is a flowchart showing the discharge process of a power storage module performed by a control unit of the backup power circuit device according to Modification 2. FIG. 10 is a graph showing the output voltage versus time elapsed when the control unit of the backup power circuit device according to Modification 2 performs the discharge process. FIG. 11 is a schematic circuit diagram showing an example of the configuration of a backup power circuit device according to Modification 3. FIG. 12 is a schematic circuit diagram showing an example of the configuration of a backup power supply circuit device according to Modification 4. FIG. 13 is a schematic circuit diagram showing an example of the configuration of a backup power supply circuit device according to Modification 5. FIG. 14 is a schematic circuit diagram showing an example of the configuration of a backup power supply circuit device according to Modification 6. FIG. 15 is a flowchart showing the charging process of the power storage module performed by the control unit of the backup power supply circuit device according to Modification 6. FIG. 16 is a graph showing the output voltage versus elapsed time when the control unit of the backup power supply circuit device according to Modification 6 performs the charging process. FIG. 17 is a schematic circuit diagram showing an example of the configuration of a backup power supply circuit device according to Modification 7. FIG. 18 is a schematic circuit diagram showing an example of the configuration of a backup power supply circuit device according to Modification 8. FIG. 19 is a schematic circuit diagram of a control unit provided in the backup power supply circuit device according to Modification 9. FIG. 20 is a schematic circuit diagram of a control unit provided in the backup power supply circuit device according to Modification 10.21 is a schematic circuit diagram of a control unit provided in a backup power supply circuit device according to Modification 11. FIG. 22 is a schematic circuit diagram of a control unit provided in a backup power supply circuit device according to Modification 11.

[0010] Hereinafter, a backup power supply circuit device according to an embodiment will be described in detail with reference to the drawings. The configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved. In addition, in the following description, the same or similar components are designated by the same reference numerals.

[0011] (Embodiment) (1) Overview As shown in FIG. 1, the backup power supply circuit device 1 according to this embodiment includes a storage module 40, a DC-DC converter 10, a charging path PA1, a first power supply path PB1, a first switch SW13, M connection ports P1, P2, a discharging path PD11, a demultiplexer M1, M second power supply paths PB11, PB12, M second switches SW11, SW12, and a third switch SW51.

[0012] The power storage module 40 includes a series circuit of N (N is an integer of 2 or more) power storage devices C1 to C3 connected in series.

[0013] The DC-DC converter 10 is connected between the DC power supply 2 and the power storage module 40, and is capable of bidirectional voltage step-up and step-down operations.

[0014] The charging path PA1 connects a series circuit of N power storage devices C1 to C3 between output terminals of the DC-DC converter 10, and supplies a charging current to the N power storage devices C1 to C3.

[0015] The first power supply path PB1 connects the power storage module 40 and the loads 31 to 34.

[0016] The first switch SW13 is inserted in the first power supply path PB1 and switches between connecting and disconnecting the power storage module 40 and the loads 31 to 34.

[0017] The M connection ports P1, P2 are connected to M (M is an integer equal to or greater than 1 and less than N) connection points out of the (N-1) connection points provided among the N power storage devices C1 to C3.

[0018] The discharge path PD11 allows a discharge current to flow from the power storage module 40 via the DCDC converter 10.

[0019] The demultiplexer M1 has a common input terminal I1 connected to the discharge path PD11, and a plurality of output terminals including M output terminals O1 and O2 connected to M connection ports P1 and P2.

[0020] The M second power supply paths PB11 and PB12 connect the M connection ports P1 and P2 to the loads 31 to 34.

[0021] The M second switches SW11 and SW12 are inserted into the M second power supply paths PB11 and PB12, and switch between connecting and disconnecting the M connection ports P1 and P2 and the loads 31 to 34, respectively.

[0022] The third switch SW51 is inserted in the discharge path PD11 and switches between connecting and disconnecting the DC-DC converter 10 and the common input terminal I1 of the demultiplexer M1.

[0023] Here, "two circuit elements being connected" does not necessarily mean that the two circuit elements are directly connected, but may also mean that the two circuit elements are indirectly connected via another circuit element. In this embodiment, each of the N power storage devices C1 to C3 included in the power storage module 40 includes, for example, an electric double layer capacitor (EDLC) capable of rapid charging and discharging. In the embodiment shown in FIG. 1 , the number of power storage devices C1 to C3 is, for example, three, and the three power storage devices C1 to C3 are connected in series in the order of C1, C2, and C3 from the low potential side. The number of power storage devices may be two or more, and may be four or more. In this embodiment, an example in which the number of power storage devices is three (i.e., N=3) will be described. Each of the power storage devices C1 to C3 includes one or more power storage cells. The capacitances of the power storage devices C1 to C3 are preferably the same, and each of the power storage devices C1 to C3 preferably has the same number of power storage cells. Note that the capacitances of the power storage devices C1 to C3 being the same do not necessarily have to be exactly the same, and the capacitances of the power storage devices C1 to C3 may vary within a range that can be considered to be a manufacturing error (for example, within a range of ±10%).

[0024] Furthermore, each of the M connection ports P1, P2 is provided between two adjacent power storage devices among the N power storage devices C1 to C3. The maximum number of connection ports P1, P2 is (N-1), but it may be less than (N-1). In the following embodiment, an example will be described in which (N-1) connection ports P1, P2 are provided between the N power storage devices C1 to C3, that is, the number (N-1) of connection points provided between the N power storage devices C1 to C3 is the same as the number M of connection ports P1, P2 (M=N-1).

[0025] The backup power supply circuit device 1 of this embodiment includes a demultiplexer M1 that connects one of the M connection ports P1, P2 to a discharge path PD11 to allow a discharge current to flow from the power storage module 40 to the DCDC converter 10. A third switch SW51 is inserted in the discharge path PD11 and switches between connecting and disconnecting the DCDC converter 10 and the common input terminal I1 of the demultiplexer M1. Therefore, when some of the power storage devices C1 to C3 discharge and the amount of charge stored among the power storage devices C1 to C3 becomes unbalanced, the demultiplexer M1 connects the connection port corresponding to the power storage device with the larger amount of charge to the DCDC converter 10 via the demultiplexer M1 and the third switch SW51. This allows the amount of charge stored among the power storage devices C1 to C3 to be equalized, while the amount of charge stored in the power storage device with the larger amount of charge can be regenerated to the DC power source 2 via the DCDC converter 10. Therefore, it is possible to provide a backup power supply circuit device 1 that can effectively utilize the remaining charge of the plurality of power storage devices C1 to C3 while eliminating the imbalance in the charge states of the plurality of power storage devices C1 to C3.

[0026] (2) Details The backup power supply circuit device 1 according to this embodiment is mounted, for example, on an automobile. The backup power supply circuit device 1 is used to supply power to on-board equipment when an abnormality occurs in the power supply from the automobile's on-board battery to the on-board equipment. This type of on-board equipment includes, for example, a driving assistance system or a by-wire system for accelerator, brake, and steering operation. The configuration and operation of the backup power supply circuit device 1 according to this embodiment will be described below. Note that the backup power supply circuit device 1 according to this embodiment may also be referred to as the basic configuration.

[0027] (2.1) Configuration As described above, the backup power supply circuit apparatus 1 according to this embodiment includes the power storage module 40, the DC-DC converter 10, the charging path PA1, the first power supply path PB1, the first switch SW13, M connection ports P1 and P2, the discharging path PD11, the demultiplexer M1, M second power supply paths PB11 and PB12, M second switches SW11 and SW12, and the third switch SW51. In this embodiment, the number N of power storage devices C1 to C3 is three, and the number M of connection ports P1 and P2 is two. The power storage module 40 includes three power storage devices C1 to C3 connected in series. The backup power supply circuit apparatus 1 also includes a pair of input terminals T1 and T2, a pair of first output terminals T3 and T4, and N second output terminals T11, T12, and T13. The backup power supply circuit device 1 further includes voltage detectors 11 to 13 and a control unit 20. In the following description, the charging path PA1 may also be referred to as the first charging path.

[0028] A pair of input terminals T1 and T2 is connected to a DC power supply 2, which is a secondary cell such as a battery.

[0029] The pair of first output terminals T3, T4 are connected to loads 31 to 34 via switches SW20 to SW23, respectively. The input terminal T1 and the first output terminal T3 are connected via a regeneration path PC2 and a voltage supply path PC1.

[0030] Furthermore, the second output terminals T11 to T13 are connected to the first output terminal T3 via, for example, a conductive member connected to the outside of the backup power supply circuit device 1. Therefore, the second output terminals T11 to T13 are connected to loads 31 to 34 via switches SW20 to SW23, respectively.

[0031] The loads 31 to 34 are, for example, on-board devices such as an automobile ECU (electronic control unit), a driving assistance system, a shift-by-wire device, a door lock device, a brake device, etc. The switches SW20 to SW23 are controlled to be turned on or off by control signals S220 to S223 input from the control unit 20. The switches SW20 to SW23 may be manually turned on or off, or may be turned on or off by a controller different from the control unit 20, for example, a controller provided external to the backup power supply circuit device 1.

[0032] The DC-DC converter 10 includes, for example, four metal-oxide-semiconductor field-effect transistor (MOSFET) switch elements Q1 to Q4, each having a parasitic diode D1 to D4, and a choke coil L1. The DC-DC converter 10 is, for example, an H-bridge buck-boost converter circuit including the four switch elements Q1 to Q4. The switch elements Q1 to Q4 are controlled to be turned on or off by control signals S1 to S4 input from a control unit 20 to their gate electrodes. In other words, the control unit 20 outputs control signals S1 to S4 to the control electrodes of the four switch elements Q1 to Q4, individually controlling the four switch elements Q1 to Q4 to be turned on or off.

[0033] A series circuit of switch elements Q1 and Q2 is connected to a pair of input terminals T1 and T2. A series circuit of power storage devices C1, C2, and C3 is connected in parallel to the series circuit of switch elements Q3 and Q4. The connection point of switch elements Q1 and Q2 is connected to the connection point of switch elements Q3 and Q4 via a choke coil L1. The drain electrode of switch element Q1 is connected to input terminal T1, which is connected to the positive electrode of DC power supply 2, and the source electrodes of switch elements Q2 and Q4 are connected to input terminal T2, which is connected to the negative electrode of DC power supply 2.

[0034] The DC-DC converter 10 includes an H-bridge type buck-boost converter circuit capable of bidirectional buck-boost operation. The operation modes of the DC-DC converter 10 include a charge mode in which the voltage input from the DC power source 2 is converted and output to the power storage module 40, and a discharge mode in which the voltage input from the power storage module 40 is converted and output to the loads 31-34 or the DC power source 2. In each of the charge mode and the discharge mode, the DC-DC converter 10 can perform a boost operation in which the input voltage is boosted and output, and a buck operation in which the input voltage is lowered and output, depending on the magnitude relationship between the input voltage and the output voltage. The operation of the DC-DC converter 10 will be described in detail in "(2.2) Description of Operation."

[0035] The backup power supply circuit apparatus 1 of this embodiment has two connection ports P1 and P2 between the three power storage devices C1, C2, and C3 that make up the power storage module 40. The connection port P1 is connected between the power storage devices C1 and C2, and the connection port P2 is connected between the power storage devices C2 and C3. The backup power supply circuit apparatus 1 also has a connection port P3 that is connected to the high-potential terminal of the power storage module 40.

[0036] The demultiplexer M1 includes a common input terminal I1 and a plurality of output terminals including two output terminals O1 and O2 connected to two connection ports P1 and P2. In this embodiment, the demultiplexer M1 includes two output terminals O1 and O2 connected to the two connection ports P1 and P2. The demultiplexer M1 also includes an internal contact that connects the common input terminal I1 to one of the two output terminals O1 and O2. The demultiplexer M1 connects the internal contact to one of the two output terminals O1 and O2 in response to a control signal S501 input from the control unit 20, thereby connecting the common input terminal I1 to one of the two output terminals O1 and O2.

[0037] The common input terminal I1 of the demultiplexer M1 is connected to the connection point between the source electrode of the switch element Q2 and the source electrode of the switch element Q4 (i.e., the negative electrode of the DC power supply 2) via a discharge path PD11. A third switch SW51 is connected to the discharge path PD11 between the common input terminal I1 and the negative electrode of the DC power supply 2. The third switch SW51 is controlled to be turned on or off by a control signal S151 input from the control unit 20.

[0038] The output terminal O1 of the demultiplexer M1 is connected to the connection port P1 via a discharge path PE11, and the output terminal O2 is connected to the connection port P2 via a discharge path PE12.

[0039] The connection port P1 is connected to the second output terminal T11 via a second power supply path PB11, and a second switch SW11 is connected to the second power supply path PB11 between the connection port P1 and the second output terminal T11. The connection port P2 is connected to the second output terminal T12 via a second power supply path PB12, and a second switch SW12 is connected to the second power supply path PB12 between the connection port P2 and the second output terminal T12. The connection port P3 is connected to the second output terminal T13 via a first power supply path PB1, and a first switch SW13 is connected to the first power supply path PB1 between the connection port P3 and the second output terminal T13.

[0040] That is, the connection ports P1 to P3 are connected to the first output terminal T3 via the second switch SW11, the second switch SW12, and the first switch SW13, respectively. The second switches SW11, SW12, and the first switch SW13 are controlled to be turned on or off by control signals S111 to S113 input from the control unit 20, respectively.

[0041] The voltage detector 11 detects the voltage V1 across the power storage device C1 and outputs a detection signal S211 indicating the voltage V1 across the power storage device C1 to the control unit 20.

[0042] The voltage detector 12 detects the voltage V2 across the power storage device C2 and outputs a detection signal S212 indicating the voltage V2 across the power storage device C2 to the control unit 20.

[0043] The voltage detector 13 detects the voltage V3 across the power storage device C3 and outputs a detection signal S213 indicating the voltage V3 across the power storage device C3 to the control unit 20.

[0044] The control unit 20 may be realized by, for example, a digital circuit mainly composed of a processor and a memory, or may be realized by an analog circuit.

[0045] The control unit 20 outputs control signals S1 to S4 to the switch elements Q1 to Q4 and controls the on / off of the switch elements Q1 to Q4, thereby causing the DCDC converter 10 to perform bidirectional voltage step-up / step-down operation. The control unit 20 outputs control signals S220 to S223 to the switches SW20 to SW23 and controls the on / off of the switches SW20 to SW23, thereby controlling the power supply to the loads 31 to 34.

[0046] The control unit 20 outputs a control signal S501 to the demultiplexer M1 to connect the common input terminal I1 of the demultiplexer M1 to one of the two output terminals O1 and O2. The control unit 20 also outputs a control signal S151 to the third switch SW51 to control the on / off of the third switch SW51.

[0047] Furthermore, the control unit 20 outputs control signals S111 to S113 to the second switch SW11, the second switch SW12, and the first switch SW13, and controls the on / off of the second switch SW11, the second switch SW12, and the first switch SW13, thereby controlling the power supply from the power storage devices C1 to C3 to the loads 31 to 34. That is, the control unit 20 controls the first switch SW13 and a switch selected from the M second switches SW11 and SW12 to be on, thereby supplying power from the power storage module 40 to the loads 31 to 34. This makes it possible to shorten the time until power supply starts compared to when power is supplied from the DCDC converter 10 to the loads 31 to 34.

[0048] (2.2) Description of Operation The operation of the backup power supply circuit device 1 of this embodiment will be described with reference to the drawings.

[0049] (2.2.1) Operation in Charging Mode of DCDC Converter The operation in normal times when power is supplied from the DC power source 2 to the loads 31 to 34 and the backup power supply circuit device 1 is not supplying power to the loads 31 to 34 will be described.

[0050] When a backup standby command is input as a control command from, for example, an ECU of an automobile, the control unit 20 controls the second switches SW11 and SW12 and the first switch SW13 to be turned off, causing the DCDC converter 10 to operate in a charging mode. The backup standby command is a control command for charging the power storage module 40 to enable backup power supply from the power storage module 40 to the loads 31 to 34. When the backup standby command is input, the control unit 20 causes the DCDC converter 10 to charge the power storage devices C1 to C3, thereby preparing for backup power supply from the power storage devices C1 to C3 to the loads 31 to 34. The control unit 20 also controls the third switch SW51 to be turned off. The control unit 20 also controls the switches SW20 to SW24 to be turned on, causing power to be supplied from the DC power source 2 to the loads 31 to 34 via the voltage supply path PC1.

[0051] When power is being supplied from the DC power source 2 to the loads 31 to 34 , the control unit 20 operates the DCDC converter 10 in a charging mode to charge the power storage module 40 .

[0052] When the DC-DC converter 10 operates in the charging mode, the DC-DC converter 10 performs a step-down operation or a step-up operation depending on the magnitude relationship between the input voltage from the DC power supply 2 and the output voltage to the power storage module 40 .

[0053] When the DC-DC converter 10 performs a step-down operation in the charging mode, the control unit 20 controls the switch element Q3 to be always on and the switch element Q4 to be always off, and alternately turns on and off the switch elements Q1 and Q2, thereby causing the DC-DC converter 10 to perform a step-down operation. The DC-DC converter 10 switches the input voltage from the DC power source 2 to step down the input voltage to a voltage value according to the duty ratio of the switch elements Q1 and Q2, and charges the power storage devices C1 to C3 via the charging path PA1.

[0054] When the DC-DC converter 10 performs a boost operation in the charging mode, the control unit 20 controls the switch element Q1 to be always on and the switch element Q2 to be always off, and alternately turns on and off the switch elements Q3 and Q4, thereby causing the DC-DC converter 10 to perform a boost operation. The DC-DC converter 10 switches the input voltage from the DC power source 2 to boost the input voltage to a voltage value according to the duty ratio of the switch elements Q3 and Q4, and charges the power storage devices C1 to C3 via the charging path PA1.

[0055] In this embodiment, the DCDC converter 10 boosts the input voltage (e.g., DC 12 V) from the DC power supply 2 to, for example, DC 48 V to charge the power storage module 40. When the DCDC converter 10 operates in the charging mode to charge the power storage devices C1 to C3, if the power storage devices C1, C2, and C3 are configured with the same number of power storage cells, the power storage devices C1, C2, and C3 are controlled to the same voltage. In this embodiment, the term "the voltages of the power storage devices C1, C2, and C3 are the same (equal)" does not necessarily mean that the voltages of the power storage devices C1, C2, and C3 are completely the same, but may include an error of about several percent (e.g., 10%).

[0056] (2.2.2) Operation of the DCDC Converter in Discharge Mode When an abnormal state occurs in which power cannot be supplied from the DC power supply 2 to the loads 31 to 34 due to, for example, a break in the electrical path connecting the DC power supply 2 and the input terminals T1 and T2, the control unit 20 operates the DCDC converter 10 in discharge mode. Then, power is supplied to the loads 31 to 34 using the power storage module 40 as a power source.

[0057] The control unit 20 controls the second switches SW11 and SW12 and the first switch SW13 to be turned off, and operates the DC-DC converter 10 in the discharge mode. The control unit 20 also controls the third switch SW51 to be turned off.

[0058] When the DC-DC converter 10 operates in the discharge mode, the control unit 20 controls at least one of the switches SW20 to SW24 to be on. The DC-DC converter 10 then steps up or steps down the input voltage from the power storage module 40 to convert it to a predetermined voltage value, and then supplies the voltage to the loads 31 to 34 via the voltage supply path PC1 and the switches SW20 to SW24. When the DC-DC converter 10 operates in the discharge mode, the DC-DC converter 10 performs a step-down operation or a step-up operation depending on the magnitude relationship between the input voltage from the power storage module 40 and the output voltage.

[0059] When the DC-DC converter 10 performs a step-down operation in discharge mode, the control unit 20 controls the switch element Q1 to be always on and the switch element Q2 to be always off, and alternately turns on and off the switch elements Q3 and Q4, thereby causing the DC-DC converter 10 to perform a step-down operation. The DC-DC converter 10 switches the input voltage from the power storage module 40, thereby stepping down the input voltage to a voltage value according to the duty ratio of the switch elements Q3 and Q4, and outputs the voltage to the loads 31 to 34.

[0060] Furthermore, when the DC-DC converter 10 performs a boost operation in discharge mode, the control unit 20 controls the switch element Q3 to be always on and the switch element Q4 to be always off, and alternately turns on and off the switch elements Q1 and Q2, thereby causing the DC-DC converter 10 to perform a boost operation. The DC-DC converter 10 switches the input voltage from the power storage module 40, thereby boosting the input voltage to a voltage value according to the duty ratio of the switch elements Q1 and Q2, and outputs the boosted voltage to the loads 31 to 34.

[0061] When the DC-DC converter 10 operates in discharge mode, if the control unit 20 controls all of the switches SW20 to SW24 to be turned off, the DC-DC converter 10 boosts or lowers the input voltage from the storage module 40 to convert it to a predetermined voltage value, and then regenerates power to the DC power source 2 via the regeneration path PC2.

[0062] (2.2.3) Direct power supply operation from the storage module When an abnormal condition occurs and the backup power supply circuit device 1 supplies power to the loads 31 to 34, it takes time for the DCDC converter 10 to start up, which causes a problem of a long response time until the DCDC converter 10 starts supplying power to the loads 31 to 34 using the storage module 40 as a power source.

[0063] Therefore, in order to shorten the response time, the control unit 20 may perform a direct power supply operation in which power is supplied directly from the power storage module 40 to the loads 31 to 34 without going through the DCDC converter 10 .

[0064] The control unit 20 can supply power to the loads 31 to 34 from any of the connection ports P1, P2, and P3, for example, by controlling one of the second switch SW11, the second switch SW12, and the first switch SW13 to be on and the others to be off until the output voltage of the DC-DC converter 10 exceeds a predetermined threshold voltage.

[0065] Based on the detection signals S211 to S213 of the voltage detectors 11 to 13, the control unit 20 connects the connection ports P1 to P3 capable of supplying the voltages required for the loads 31 to 34 to the first output terminal T3, and supplies power from these connection ports to the loads 31 to 34. At the start of power supply, the power storage devices C1, C2, and C3 are all fully charged, so the control unit 20 controls the second switch SW11 to be on and the second switch SW12 and the first switch SW11 to be off, thereby supplying power from the power storage device C1 to the loads 31 to 34. Thereafter, when the voltage of the power storage device C1 drops and it becomes unable to supply the voltage required for the loads 31 to 34, the control unit 20 controls the second switch SW11 and the first switch SW11 to be off and the second switch SW12 to be on, thereby supplying power from the power storage devices C1 and C2 to the loads 31 to 34. Thereafter, when the voltage of the power storage devices C1 and C2 drops and it becomes impossible to supply the necessary voltage to the loads 31 to 34, the control unit 20 controls the second switches SW11 and SW12 to be turned off and the first switch SW13 to be turned on, thereby supplying power from the power storage devices C1, C2, and C3 to the loads 31 to 34.

[0066] In this way, the control unit 20 can supply power directly from the storage module 40 to the loads 31 to 34 by turning on either the second switch SW11, SW12 or the first switch SW13, thereby shortening the response time until power supply to the loads 31 to 34 begins.

[0067] It is not essential that the control unit 20 turn on any of the second switches SW11, SW12 and the first switch SW13 to perform a direct power supply operation to directly supply power from the power storage module 40 to the loads 31 to 34 before the DC-DC converter 10 is started. The control unit 20 may perform a direct power supply operation when it is necessary to shorten the response time until the start of power supply depending on the loads 31 to 34 to be supplied with power.

[0068] (2.2.4) Discharge processing of the storage module When the backup power supply circuit device 1 performs the direct power supply operation described in "(2.2.3) Direct power supply operation from the storage module," the amount of charge released is greatest for the storage device C1 and least for the storage device C3, resulting in an imbalance in the charge states of the storage devices C1, C2, and C3.

[0069] In this way, when the DCDC converter 10 recharges the power storage devices C1 to C3 after the charge states of the power storage devices C1 to C3 become unbalanced, the charging current is limited by the power storage device C3, which has the largest remaining charge among the power storage devices C1 to C3, so there is a possibility that the other power storage devices C1 and C2 cannot be fully charged. Furthermore, when the charge of the power storage devices C1 to C3 is regenerated to the DC power supply 2 after the charge states of the power storage devices C1 to C3 become unbalanced, the discharge current is limited by the power storage device C1, which has the smallest remaining charge among the power storage devices C1 to C3, so there is a possibility that the charge of the other power storage devices C2 and C3 cannot be sufficiently regenerated. Furthermore, if the power storage devices C1 to C3, which are EDLCs, are left with charge remaining in them, there is a possibility that deterioration of the power storage devices C1 to C3 will progress.

[0070] Therefore, the backup power supply circuit device 1 of this embodiment is provided with a discharge path PD11 and a demultiplexer M1 that connects either the connection port P1 or P2 to the discharge path PD11, and eliminates the imbalance in the charge state by discharging the charge of the storage devices C2 and C3 that have a large amount of remaining charge.

[0071] The discharge process in which the control unit 20 discharges the electric charges of the power storage devices C1 to C3 to eliminate the imbalance will be described with reference to Figures 2 and 3. The flowchart shown in Figure 2 is merely an example of the discharge process of the power storage module 40 performed by the control unit 20, and the order of the processes may be changed as appropriate, and processes may be added or omitted as appropriate. Figure 3 is a graph showing the change over time in the output voltage Vout of the power storage module 40 when the control unit 20 performs the discharge process. The output voltage Vout of the power storage module 40 is a composite voltage of the voltages V1, V2, and V3 across the power storage devices C1, C2, and C3, and is expressed as Vout = V1 + V2 + V3.

[0072] The control unit 20 acquires the detection signals S211, S212, S213 from the voltage detectors 11, 12, 13, and acquires the voltages V1, V2, V3 across the power storage devices C1, C2, C3 (ST1).

[0073] The control unit 20 determines whether the voltages V2 and V3 across the power storage devices C2 and C3 are the same (ST2), and if the voltages V2 and V3 across the power storage devices C2 and C3 are the same (ST2: No), the control unit 20 proceeds to step ST6, and if the voltages V2 and V3 across the power storage devices C2 and C3 are not the same (ST2: Yes), the control unit 20 proceeds to step ST3.

[0074] In step ST3 (a state in which the charge states of the power storage devices C2 and C3 are unbalanced), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O2 and controls the third switch SW51 to be on to discharge the power storage device C3 (time point t1 in FIG. 3 ). The control unit 20 controls the first switch SW13 to be off, the second switches SW11 and SW12 to be off, and the switches SW20 to SW23 to be off to stop the power supply to the loads 31 to 34. The control unit 20 then operates the DCDC converter 10 in a discharge mode to discharge the charge of the power storage device C3 from the DCDC converter 10, the DC power source 2, the third switch SW51, the discharge path PD11, and the demultiplexer M1. As the charge in the power storage device C3 is released, the voltage V3 across the power storage device C3 decreases, and the output voltage Vout gradually decreases from the initial value Vint (time t1 to t2 in FIG. 3).

[0075] The control unit 20 sequentially determines whether the voltages V2 and V3 across the power storage devices C2 and C3 are the same (ST4), and if the voltages V2 and V3 across the power storage devices C2 and C3 are not the same (ST4: No), the control unit 20 continues to discharge charge from the power storage device C3 (ST3).

[0076] Thereafter, when the voltages V2 and V3 across the power storage devices C2 and C3 become the same (ST4: Yes), the control unit 20 turns off the third switch SW51 to stop the release of charge from the power storage device C3 (ST5), and proceeds to step ST6. Time t2 in Fig. 3 is the timing when the voltages V2 and V3 across the power storage devices C2 and C3 become the same, at which point the third switch SW51 is turned off and the release of charge from the power storage device C3 is stopped.

[0077] In step ST6, the control unit 20 determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same. If the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST6: No), the control unit 20 proceeds to step ST10. If the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST6: Yes), the control unit 20 proceeds to step ST7.

[0078] In step ST7 (a state in which the charge states of the power storage devices C1 and C2 are unbalanced), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O1 and controls the third switch SW51 to be on, thereby discharging the power storage devices C2 and C3 (time t3 in FIG. 3 ). The control unit 20 operates the DCDC converter 10 in a discharge mode, thereby discharging the electric charge of the power storage devices C2 and C3 from the DCDC converter 10, the DC power supply 2, the third switch SW51, the discharge path PD11, and the demultiplexer M1. As the electric charge of the power storage devices C2 and C3 is discharged, the voltages V2 and V3 across the power storage devices C2 and C3 decrease, and the output voltage Vout gradually decreases from the voltage value Vm1 at time t3 (times t3 to t4 in FIG. 3 ). The voltage value Vm1 is the voltage value of the output voltage Vout when the voltages V2 and V3 across both ends are equal, and is expressed as Vm1=2×V2+V1.

[0079] The control unit 20 sequentially determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST8), and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST8: No), the control unit 20 continues to discharge charge from the power storage devices C2 and C3 (ST7).

[0080] Thereafter, when the voltages V1 and V2 across the power storage devices C1 and C2 become the same (ST8: Yes), the control unit 20 turns off the third switch SW51 to stop the release of charge from the power storage devices C2 and C3 (ST9), and proceeds to step ST10. Time t4 in Fig. 3 is the timing when the voltages V1 and V2 across the power storage devices C1 and C2 become the same, at which point the third switch SW51 is turned off and the release of charge from the power storage devices C2 and C3 is stopped.

[0081] In step ST10, the control unit 20 determines whether the output voltage Vout of the storage module 40 is 0 or not, and if the output voltage Vout is 0 (ST10: No), the control unit 20 terminates the discharge process, and if the output voltage Vout is not 0 (ST10: Yes), the control unit 20 proceeds to step ST11.

[0082] In step ST11, the control unit 20 operates the DCDC converter 10 in a discharge mode (time t5 in FIG. 3 ), discharging the electric charge of the electric storage devices C1, C2, and C3 from the DCDC converter 10, the DC power supply 2, and the discharge path PD1. As the electric charge of the electric storage devices C1, C2, and C3 is discharged, the voltages V1, V2, and V3 across the electric storage devices C1, C2, and C3 decrease, and the output voltage Vout gradually decreases from the voltage value Vm2 at time t5 (times t5 to t6 in FIG. 3 ). The voltage value Vm2 is the voltage value of the output voltage Vout when the voltages V1, V2, and V3 become equal, and is expressed as Vm2 = 3 × V1.

[0083] The control unit 20 sequentially determines whether the output voltage Vout of the storage module 40 is zero (ST12), and if the output voltage Vout is not zero (ST12: No), it continues to discharge charge from the storage devices C1, C2, and C3 (ST11).

[0084] Thereafter, when the output voltage Vout becomes zero (ST12: Yes), the control unit 20 stops the operation of the DCDC converter 10 (ST13) and stops the discharge process.

[0085] As described above, the backup power supply circuit apparatus 1 further includes voltage detectors 11 to 13 that detect the voltages of N (for example, three in this embodiment) power storage devices C1 to C3, and a control unit 20 that controls the demultiplexer M1. In a state in which the control unit 20 controls the demultiplexer M1 to connect a connection port between the Pth (P is an integer equal to or greater than 2 and less than N) power storage device CP counting from the low potential side and the (P+1)th power storage device CP+1 to the discharge path PD11, when the voltage of the (P+1)th power storage device CP+1 and the voltage of the Pth power storage device CP become equal, the control unit 20 controls the demultiplexer M1 to connect a connection port between the Pth power storage device CP counting from the low potential side and the (P−1)th power storage device CP−1 to the discharge path PD11.

[0086] As a result, even if the charges of the power storage devices C1, C2, and C3 become unbalanced, the control unit 20 can discharge the charges of the power storage devices C1, C2, and C3 so as to maintain a balance in the charge states of the power storage devices C1, C2, and C3. A state in which the charge states of the power storage devices C1, C2, and C3 are balanced refers to a state in which the amounts of charge stored in the power storage devices C1, C2, and C3 are equal, and the voltages V1, V2, and V3 across the power storage devices C1, C2, and C3 are the same. After maintaining a balance in the charge states of the power storage devices C1, C2, and C3, the control unit 20 discharges the charges of the power storage devices C1, C2, and C3 until the charge of the power storage devices C1, C2, and C3 becomes zero. This reduces the possibility that the power storage devices C1, C2, and C3 will be left with residual charge, and suppresses deterioration of the power storage devices C1, C2, and C3, which are EDLCs. Furthermore, the charge stored in the power storage devices C1, C2, and C3 can be regenerated to the DC power supply 2 while the voltages V1, V2, and V3 across the power storage devices C1, C2, and C3 can be reduced to zero, so that the charge in the power storage devices C1, C2, and C3 is not wasted and can be used effectively.

[0087] In addition, when the voltages of the N power storage devices C1 to C3 become the same voltage by flowing a discharge current through the discharge path PD11, the control unit 20 may control the third switch SW51 to be turned off and then cause the DCDC converter 10 to charge the N power storage devices C1 to C3.

[0088] As a result, after the charge states of the N power storage devices C1 to C3 are kept balanced, the N power storage devices C1 to C3 can be charged and prepared for power supply to the loads 31 to .

[0089] (3) Modifications The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0090] Modifications of the above embodiment are listed below. The modifications described below can be applied in appropriate combinations. In the modifications described below, components that are the same as or similar to those of the backup power supply circuit device 1 having the basic configuration are given the same reference numerals, and descriptions thereof will be omitted.

[0091] (3.1) Modification 1 Fig. 4 is a schematic circuit diagram of a backup power supply circuit apparatus 1 of Modification 1. The backup power supply circuit apparatus 1 of Modification 1 differs from the basic configuration in that the power storage module 40 includes two power storage devices C1 and C2 connected in series.

[0092] In variant example 1, the energy storage module 40 is composed of two energy storage devices C1 and C2 connected in series, so there is one connection point between the two energy storage devices C1 and C2, and one connection port P1 is provided between the two energy storage devices C1 and C2.

[0093] In Modification 1, a series circuit of two power storage devices C1 and C2 is connected between output terminals of the DC-DC converter 10. The two power storage devices C1 and C2 are connected in series in this order from the low potential side. A first end of the power storage device C1 is connected to the negative electrode of the DC power source 2. A second end of the power storage device C1 is connected to a first end of the power storage device C2. A second end of the power storage device C2 is connected to the drain electrode of the switch element Q3.

[0094] A connection port P1 provided at the connection point between the power storage devices C1 and C2 is connected to a second output terminal T11 via a second power supply path PB11. A second switch SW11 is connected to the second power supply path PB11 between the connection port P1 and the second output terminal T11. The second switch SW11 is controlled to be turned on or off by a control signal S111 input from the control unit 20.

[0095] A connection port P3 is provided at a second end of the power storage device C2, and the connection port P3 is connected to a second output terminal T13 via a first power supply path PB1. A first switch SW13 is connected to the first power supply path PB1 between the connection port P3 and the second output terminal T13. The first switch SW13 is controlled to be turned on or off by a control signal S113 input from the control unit 20.

[0096] Similar to the basic configuration, the demultiplexer M1 has a common input terminal I1 and two output terminals O1 and O2. In Modification 1, the demultiplexer M1 has multiple output terminals O1 and O2, including the output terminal O1 connected to the connection port P1, and the output terminal O2 is not connected to a connection port. The demultiplexer M1 also has internal contacts that connect the common input terminal I1 to one of the two output terminals O1 and O2. The demultiplexer M1 connects the internal contacts to one of the two output terminals O1 and O2 in response to a control signal S501 input from the control unit 20, thereby connecting the common input terminal I1 to one of the two output terminals O1 and O2.

[0097] The common input terminal I1 of the demultiplexer M1 is connected to the connection point between the source electrode of the switch element Q2 and the source electrode of the switch element Q4 (i.e., the negative electrode of the DC power supply 2) via a discharge path PD11. A third switch SW51 is connected to the discharge path PD11 between the common input terminal I1 and the negative electrode of the DC power supply 2. The third switch SW51 is controlled to be turned on or off by a control signal S151 input from the control unit 20.

[0098] The output terminal O1 of the demultiplexer M1 is connected to the connection port P1 via a discharge path PE11. Nothing is connected to the output terminal O2, and it is in an open state.

[0099] In Modification 1, the discharge process performed by the control unit 20 to eliminate the imbalance in the charge states of the power storage devices C1 and C2 will be described with reference to Fig. 5 and Fig. 6. The flowchart shown in Fig. 5 is merely an example of the discharge process of the power storage module 40 performed by the control unit 20, and the order of the processes may be changed as appropriate, and processes may be added or omitted as appropriate. Fig. 6 is a graph showing the change over time in the output voltage Vout of the power storage module 40 when the control unit 20 performs the discharge process.

[0100] The control unit 20 acquires, for example, detection signals S211 and S212 from the voltage detectors 11 and 12, and acquires voltages V1 and V2 across the power storage devices C1 and C2 (ST21).

[0101] The control unit 20 determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST22), and if the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST22: No), the control unit 20 proceeds to step ST26, and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST22: Yes), the control unit 20 proceeds to step ST23.

[0102] In step ST23 (a state in which the charge states of the power storage devices C1 and C2 are unbalanced), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O1 and controls the third switch SW51 to be on to discharge the power storage device C2 (time point t11 ​​in FIG. 6 ). The control unit 20 controls the first switch SW13 to be off, the second switch SW11 to be off, and the switches SW20 to SW23 to be off to stop the power supply to the loads 31 to 34. Then, the control unit 20 operates the DCDC converter 10 in a discharge mode to discharge the charge of the power storage device C2 from the power storage device C2 via the DCDC converter 10, the DC power source 2, the third switch SW51, the discharge path PD11, and the demultiplexer M1. As the charge in the power storage device C2 is released, the voltage V2 across the power storage device C2 decreases, and the output voltage Vout gradually decreases from the initial value Vint (time t11 to t12 in FIG. 3).

[0103] The control unit 20 sequentially determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST24), and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST24: No), it continues to discharge charge from the power storage device C2 (ST23).

[0104] Thereafter, when the voltages V1 and V2 across the power storage devices C1 and C2 become the same (ST24: Yes), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O2 and turns off the third switch SW51 to stop the release of charge from the power storage device C2 (ST25), and proceeds to step ST26. Time t12 in Figure 6 is the timing when the voltages V1 and V2 across the power storage devices C1 and C2 become the same, at which point the internal contact of the demultiplexer M1 is connected to the output terminal O2, the third switch SW51 is turned off, and the release of charge from the power storage device C2 is stopped.

[0105] In step ST26, the control unit 20 determines whether the output voltage Vout of the storage module 40 is 0 or not, and if the output voltage Vout is 0 (ST26: No), the control unit 20 terminates the discharge process, and if the output voltage Vout is not 0 (ST26: Yes), the control unit 20 proceeds to step ST27.

[0106] In step ST27, the control unit 20 operates the DCDC converter 10 in the discharge mode (time point t13 in FIG. 6 ), discharging the electric charge of the electric storage devices C1, C2 from the DCDC converter 10, the DC power supply 2, and the discharge path PD1. As the electric charge of the electric storage devices C1, C2 is discharged, the voltages V1, V2 across the electric storage devices C1, C2 decrease, and the output voltage Vout gradually decreases from the voltage value Vm1 at time point t13 (time points t13 to t14 in FIG. 6 ). The voltage value Vm1 is the voltage value of the output voltage Vout when the voltages V1, V2 become equal, and is expressed as Vm1 = 2 × V1.

[0107] The control unit 20 sequentially determines whether the output voltage Vout of the storage module 40 is zero (ST28), and if the output voltage Vout is not zero (ST28: No), continues to discharge charge from the storage devices C1 and C2 (ST27).

[0108] Thereafter, when the output voltage Vout becomes zero (ST28: Yes), the control unit 20 stops the operation of the DCDC converter 10 (ST29) and stops the discharge process.

[0109] In this way, even if the charges of the power storage devices C1 and C2 become unbalanced, the control unit 20 can eliminate the imbalance in the charge states of the power storage devices C1 and C2 and discharge the charges of the power storage devices C1 and C2 until the charges become zero. This reduces the possibility that the power storage devices C1 and C2 will be left with charges remaining, and can suppress deterioration of the power storage devices C1 and C2, which are EDLCs. Furthermore, since the charges stored in the power storage devices C1 and C2 can be regenerated to the DC power supply 2 while the voltages V1 and V2 across the power storage devices C1 and C2 can be reduced to zero, the charges of the power storage devices C1 and C2 can be effectively used without being wasted.

[0110] In addition, if the demultiplexer M1 is configured so that the output terminal O1 is in a high impedance state when the internal contact of the demultiplexer M1 is connected to the output terminal O2, the switch connected between the negative pole of the DC power supply 2 and the common input terminal I1 can be omitted, as shown in FIG. 7 . In other words, since the demultiplexer M1 has the function of the third switch, there is no need to provide a switch separate from the demultiplexer M1. Furthermore, since the demultiplexer M1 also functions as the third switch, there is no need to control a switch provided separately from the demultiplexer M1, and the configuration of the control unit 20 can be simplified. In other words, the third switch may be a switch provided separately from the demultiplexer M1, or may be a switch function realized by the demultiplexer M1.

[0111] In the circuit examples of Figures 4 and 7, the number of storage devices C1, C2 that make up the storage module 40 is two, but the number of storage devices C1, C2 that make up the storage module 40 may be three or more and can be changed as appropriate.

[0112] (3.2) Modification 2 FIG. 8 is a schematic circuit diagram of a backup power supply circuit device 1 according to Modification 2. In FIG.

[0113] In the basic configuration, (N-1) connection ports P1, P2 are provided between N storage devices C1 to C3, whereas in variant 2, fewer than (N-1) connection ports are provided between N storage devices C1 to C3, which is different from the basic configuration.

[0114] More specifically, in Modification 2, a connection port P1 is provided between the power storage devices C1 and C2, but no connection port is provided between the power storage devices C2 and C3. The output terminal O1 of the demultiplexer M1 is connected to the connection port P1 via a discharge path PE11, but nothing is connected to the output terminal O2 of the demultiplexer M1, and the output terminal O2 is in an open state. Furthermore, in Modification 2, the second power supply path PB12 including the second switch SW12 is omitted.

[0115] In Modification 2, because no connection port is provided between the power storage devices C2 and C3, which have the same capacitance, the charge states of the power storage devices C2 and C3 are balanced. On the other hand, since there may be cases where the charge states of the power storage devices C1 and C2 and C3 are unbalanced, the control unit 20 determines whether the charge states of the power storage devices C1, C2, and C3 are balanced by comparing the detection signal S211 with either one of the detection signals S213 and S212. When performing a discharge process for the power storage devices C1 to C3, if the charge states of the power storage devices C1 to C3 are balanced, the control unit 20 discharges the charges of all of the power storage devices C1 to C3 via the DCDC converter 10, regenerating power to the DC power source 2, and reducing the charges of all of the power storage devices C1 to C3 to zero.

[0116] In Modification 2, the discharge process in which the control unit 20 discharges the charges of the power storage devices C1 to C3 to eliminate the imbalance will be described with reference to Figures 9 and 10. The flowchart shown in Figure 9 is merely an example of the discharge process of the power storage module 40 performed by the control unit 20, and the order of the processes may be changed as appropriate, and processes may be added or omitted as appropriate. Figure 10 is a graph showing the change over time in the output voltage Vout of the power storage module 40 when the control unit 20 performs the discharge process.

[0117] The control unit 20 acquires, for example, detection signals S211 and S212 from the voltage detectors 11 and 12, and acquires voltages V1 and V2 across the power storage devices C1 and C2 (ST31).

[0118] The control unit 20 determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST32), and if the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST32: No), the control unit 20 proceeds to step ST36, and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST32: Yes), the control unit 20 proceeds to step ST33.

[0119] In step ST33 (a state in which the charge states of the power storage devices C1 and C2 are unbalanced), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O1 and controls the third switch SW51 to be on, thereby discharging the power storage devices C2 and C3 (time t21 in FIG. 10 ). The control unit 20 operates the DCDC converter 10 in a discharge mode, thereby discharging the electric charge of the power storage devices C2 and C3 from the DCDC converter 10, the DC power supply 2, the third switch SW51, the discharge path PD11, and the demultiplexer M1. As the electric charge of the power storage devices C2 and C3 is discharged, the voltages V2 and V3 across the power storage devices C2 and C3 decrease, and the output voltage Vout gradually decreases from the voltage value Vint at time t21 (times t21 to t22 in FIG. 10 ).

[0120] The control unit 20 sequentially determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST34), and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST34: No), it continues to discharge charge from the power storage devices C2 and C3 (ST33).

[0121] Thereafter, when the voltages V1 and V2 across the power storage devices C1 and C2 become the same (ST34: Yes), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O2 and turns off the third switch SW51 to stop the release of charge from the power storage devices C2 and C3 (ST35), and proceeds to step ST36. Time t22 in Figure 10 is the timing when the voltages V1 and V2 across the power storage devices C1 and C2 become the same, at which point the internal contact of the demultiplexer M1 is connected to the output terminal O2, the third switch SW51 is turned off, and the release of charge from the power storage devices C2 and C3 is stopped.

[0122] In step ST36, the control unit 20 determines whether the output voltage Vout of the storage module 40 is 0 or not, and if the output voltage Vout is 0 (ST36: No), the control unit 20 terminates the discharge process, and if the output voltage Vout is not 0 (ST36: Yes), the control unit 20 proceeds to step ST37.

[0123] In step ST37, the control unit 20 operates the DCDC converter 10 in the discharge mode (time t23 in FIG. 10 ), discharging the electric charge of the electric storage devices C1, C2, and C3 from the DCDC converter 10, the DC power supply 2, and the discharge path PD1. As the electric charge of the electric storage devices C1, C2, and C3 is discharged, the voltages V1, V2, and V3 across the electric storage devices C1, C2, and C3 decrease, and the output voltage Vout gradually decreases from the voltage value Vd1 at time t23 (times t23 to t24 in FIG. 10 ). The voltage value Vd1 is the voltage value of the output voltage Vout when the voltages V1, V2, and V3 become equal, and is expressed as Vd1=3×V1.

[0124] The control unit 20 sequentially determines whether the output voltage Vout of the storage module 40 is zero (ST38), and if the output voltage Vout is not zero (ST38: No), it continues to discharge charge from the storage devices C1, C2, and C3 (ST37).

[0125] Thereafter, when the output voltage Vout becomes zero (ST38: Yes), the control unit 20 stops the operation of the DCDC converter 10 (ST39) and stops the discharge process.

[0126] In this way, even when the charges of the power storage devices C1, C2, and C3 become unbalanced, the control unit 20 can eliminate the imbalance in the charge states of the power storage devices C1, C2, and C3 and discharge the charges of the power storage devices C1, C2, and C3 until the charges become zero. This reduces the possibility that the power storage devices C1, C2, and C3 will be left with charges remaining, thereby suppressing deterioration of the power storage devices C1, C2, and C3, which are EDLCs. Furthermore, the charges stored in the power storage devices C1, C2, and C3 can be regenerated to the DC power supply 2 while the voltages V1, V2, and V3 across the power storage devices C1, C2, and C3 can be reduced to zero. This prevents the charges of the power storage devices C1, C2, and C3 from being wasted and allows the charges to be used effectively.

[0127] Since the control unit 20 compares the voltage V1 of the power storage device C1 with the voltage V2 of the power storage device C2, the voltage detector 13 that detects the voltage V3 of the power storage device C3 can be omitted.

[0128] Furthermore, since the voltages V2 and V3 of the power storage devices C2 and C3, which have the same capacitance, are the same, the control unit 20 may compare the voltage V1 of the power storage device C1 with the voltage V3 of the power storage device C3. In this case, the voltage detector 12 that detects the voltage V2 of the power storage device C2 can be omitted.

[0129] (3.3) Modification 3 FIG. 11 is a schematic circuit diagram showing an example of the configuration of the backup power supply circuit device 1 according to Modification 3.

[0130] The third modification differs from the basic configuration in that the third switch SW51 includes a series circuit of a diode D61 and an insulated gate transistor Q51.

[0131] The insulated gate transistor Q51 is realized by a MOSFET having a parasitic diode D51. The insulated gate transistor Q51 is controlled to be turned on or off by a control signal S51 input from the control unit 20 to the gate electrode.

[0132] The cathode of the diode D61 is connected to the drain electrode of the insulated gate transistor Q51, and the anode of the diode D61 is connected to the negative electrode of the DC power supply 2.

[0133] The source electrode of the insulated gate transistor Q51 is connected to the common input terminal I1 of the demultiplexer M1. The insulated gate transistor Q51 is controlled to be turned on or off by a control signal S51 input from the control unit 20.

[0134] Thus, the third switch SW51 preferably includes a series circuit of a diode D61 and an insulated gate transistor Q51.

[0135] In the backup power supply circuit device 1 according to the third modification, the diode D61 can prevent the discharge of the power storage device C1 via the discharge path PD11. Since the diode D61 does not require a drive circuit, the cost of the control unit 20 can be reduced.

[0136] In the third modification, since the diode D61 and the insulated gate transistor Q51 are connected in series, the order of the connections may be reversed.

[0137] (3.4) Modification 4 FIG. 12 is a schematic circuit diagram showing an example of the configuration of the backup power supply circuit device 1 according to Modification 4.

[0138] The fourth modification differs from the basic configuration in that the third switch SW51 includes a series circuit of two MOS field effect transistors (hereinafter abbreviated as MOSFETs) Q51 and Q52 connected in series in the opposite directions.

[0139] More specifically, the third switch SW51 includes a common-drain connection circuit of a MOSFET Q52 having a parasitic diode D52 and a MOSFET Q51 having a parasitic diode D51. Here, the common-drain connection circuit refers to a circuit in which the drains of two MOSFETs are connected together and the two MOSFETs are connected in opposite directions.

[0140] MOSFETs Q51 and Q52 are controlled to be on or off in response to control signals S51 and S52 input to their gate electrodes from control unit 20. When discharging the charge of power storage device C2 or power storage devices C2 and C3 via discharge path PD11, control unit 20 controls MOSFETs Q51 and Q52 to be on.

[0141] As described above, the third switch SW51 preferably includes a series circuit of two MOS field effect transistors (MOSFETs) Q51 and Q52 connected in series in the opposite directions.

[0142] In the fourth modification, the MOSFETs Q51 and Q52 can prevent the discharge of the power storage device C1 via the discharge path PD11. In the fourth modification, the MOSFETs Q51 and Q52 with low on-resistance are used to prevent the discharge of the power storage devices C1 and C2, so that the loss during discharge can be reduced compared to the configuration using the diode D61 as in the third modification.

[0143] 12, the third switch SW51 includes a common-drain connection circuit of two MOSFETs Q51 and Q52, but it may also include a common-source connection circuit of two MOSFETs. A common-source connection circuit is a circuit in which the sources of two MOSFETs are connected together and the two MOSFETs are connected in opposite directions. When the third switch SW51 includes a common-source connection circuit of two MOSFETs, it has the same effect as when it includes a common-drain connection circuit of two MOSFETs.

[0144] (3.5) Modification 5 FIG. 13 is a schematic circuit diagram showing an example of the configuration of the backup power supply circuit device 1 according to Modification 5.

[0145] The fifth modification differs from the basic configuration in that at least one of the first switch SW13 and the M second switches SW11 and SW12 includes a series circuit of two MOS field effect transistors connected in series in opposite directions.

[0146] 13, each of the first switch SW13 and the M second switches SW11 and SW12 includes a series circuit of two MOS field effect transistors connected in series in opposite directions. Because each of the first switch SW13 and the M second switches SW11 and SW12 is configured with a series circuit of two MOS field effect transistors connected in series in opposite directions, current can be cut off in both directions by controlling the two MOS field effect transistors to be off.

[0147] More specifically, the first switch SW13 includes a common-drain connection circuit of two MOSFETs Q33 and Q36, each having a parasitic diode D33 and D36. The second switch SW11 includes a common-drain connection circuit of two MOSFETs Q31 and Q34, each having a parasitic diode D31 and D34. The second switch SW12 includes a common-drain connection circuit of two MOSFETs Q32 and Q35, each having a parasitic diode D32 and D35.

[0148] The MOSFETs Q31 to Q36 are respectively controlled to be on or off in response to control signals S31 to S36 input to their gate electrodes from the control unit 20. When power is supplied to the loads 31 to 34 via the first power supply path PB1, the control unit 20 controls the MOSFETs Q33 and Q36 to be on and the MOSFETs Q31, Q32, Q34, and Q35 to be off. When power is supplied to the loads 31 to 34 via the second power supply path PB11, the control unit 20 controls the MOSFETs Q31 and Q34 to be on and the MOSFETs Q32, Q33, Q35, and Q36 to be off. When power is supplied to the loads 31 to 34 via the second power supply path PB12, the control unit 20 controls the MOSFETs Q32 and Q35 to be on and the MOSFETs Q31, Q33, Q34, and Q36 to be off.

[0149] In the circuit example shown in FIG. 13, each of the first switch SW13 and the M second switches SW11 and SW12 includes a common-drain connection circuit of two MOSFETs, but may also include a common-source connection circuit of two MOSFETs.

[0150] That is, the first switch SW13 may include a common-source connection circuit of two MOSFETs Q33 and Q36, each having a parasitic diode D33 and D36. The second switch SW11 may include a common-source connection circuit of two MOSFETs Q31 and Q34, each having a parasitic diode D31 and D34. The second switch SW12 may include a common-source connection circuit of two MOSFETs Q32 and Q35, each having a parasitic diode D32 and D35.

[0151] (3.6) Modification 6 FIG. 14 is a schematic circuit diagram showing an example of the configuration of the backup power supply circuit device 1 according to Modification 6.

[0152] The backup power supply circuit device 1 according to the sixth modification differs from the basic configuration in that the connection point between the switch elements Q3 and Q4 is connected to the common input terminal I1 of the demultiplexer M1 via a fourth switch SW1 and a second charging path PA11. The fourth switch SW1 is controlled to be turned on or off in response to a control signal S101 input from the control unit 20.

[0153] More specifically, a first terminal of a fourth switch SW1 is connected to the connection point between the source electrode of the switch element Q3 and the drain electrode of the switch element Q4. A second terminal of the fourth switch SW1 is connected to the common input terminal I1 of the demultiplexer M1.

[0154] In this way, the backup power supply circuit device 1 of Modification 6 includes a second charging path PA11 that connects the common input terminal I1 of the demultiplexer M1 and the DCDC converter 10 and allows a charging current to flow from the DCDC converter 10 to the power storage module 40. The backup power supply circuit device 1 also includes a fourth switch SW1 that is inserted into the second charging path PA11 and switches whether or not the DCDC converter 10 and the common input terminal I1 are connected.

[0155] In variant example 6, the control unit 20 operates the DC-DC converter 10 in charging mode, connects the internal contact of the demultiplexer M1 to the output terminal O1 or O2, and controls the third switch SW51 to be off and the fourth switch SW1 to be on, thereby charging the storage device C1 or both the storage devices C1 and C2 via the second charging path PA11.

[0156] For example, the control unit 20 can selectively charge the power storage device C1 via the second charge path PA11 and the discharge path PE11 by connecting the internal contact of the demultiplexer M1 to the output terminal O1, turning off the third switch SW51, and turning on the fourth switch SW1. This eliminates an imbalance in the charge states between the power storage device C1 and the power storage device C2 connected to the high potential side of the power storage device C1, and maintains a balance in the charge states of the power storage devices C1 and C2. In addition, in Modification 6, when the discharge path PE11 is also used as a charge path, the discharge path PE11 may also be referred to as a charge / discharge path.

[0157] Furthermore, the control unit 20 controls the power storage devices C1 and C2 to be selectively charged via the second charge path PA11 and the discharge path PE12 by connecting the internal contact of the demultiplexer M1 to the output terminal O2, turning off the third switch SW51, and turning on the fourth switch SW1. This eliminates the imbalance in the charge states between the power storage device C3 connected to the high potential side of the power storage device C2 and the power storage devices C1 and C2. In addition, in the sixth modification, when the discharge path PE12 is also used as a charge path, the discharge path PE12 may also be referred to as a charge / discharge path.

[0158] In addition, the control unit 20 controls the fourth switch SW1 and the third switch SW51 to be off and operates the DC-DC converter 10 in charging mode, thereby charging the storage module 40 via the first charging path PA1 and charging all of the storage devices C1 to C3 to a fully charged state.

[0159] In the sixth modification, an external control device 1000 (external system) such as an ECU of an automobile inputs a power supply unnecessary signal S1001 as a control command to the control unit 20, notifying the control unit 20 that power supply from the power storage module 40 to the loads 31 to 34 is unnecessary. The control unit 20 determines whether or not an imbalance has occurred in the charge states of the power storage devices C1 to C3 based on the detection signals S211 to S213 of the voltage detectors 11 to 13.

[0160] When the control unit 20 determines that the charge states of the power storage devices C1 to C3 are unbalanced and receives a power supply unnecessary signal S1001 from the external control device 1000 (this state is referred to as a first unbalanced state), the control unit 20 performs a discharge process via the discharge path PD11 and the charge / discharge paths PE11 and PE12, thereby regenerating the charge of the power storage devices C1 to C3 to the DC power supply 2 and reducing the charge of all of the power storage devices C1 to C3 to zero, thereby eliminating the unbalanced charge states. The discharge process performed by the control unit 20 in the first unbalanced state is the same as the process described in the basic configuration (see FIGS. 2 and 3), and therefore a description thereof will be omitted.

[0161] On the other hand, when the control unit 20 determines that the charge states of the power storage devices C1 to C3 are unbalanced and no power supply unnecessary signal S1001 is input from the external control device 1000 (this state is referred to as a second unbalanced state), the control unit 20 charges the power storage device C1 or the power storage devices C1 and C2 via the second charging path PA11 and the charge / discharge paths PE11 and PE12, thereby eliminating the imbalance in the charge states of the power storage devices C1 to C3. Then, when the charge states of the power storage devices C1 to C3 are balanced, the control unit 20 charges all of the power storage devices C1 to C3 using the DCDC converter 10, charging all of the power storage devices C1 to C3 to a fully charged state and preparing to supply power to the loads 31 to 34. Note that the state in which no power supply unnecessary signal S1001 is input from the external control device 1000 is, in other words, a state in which a backup standby command is input from the external control device 1000. Therefore, the second unbalanced state is also a state in which a backup standby command is input as a control command from the external control device 1000.

[0162] Here, the charging process of the power storage module 40 performed by the control unit 20 in the second unbalanced state will be described with reference to Fig. 15 and Fig. 16. The flowchart shown in Fig. 15 is merely an example of the charging process of the power storage module 40 performed by the control unit 20, and the order of the processes may be changed as appropriate, and processes may be added or omitted as appropriate. Fig. 16 is a graph showing the change over time in the output voltage Vout of the power storage module 40 when the control unit 20 performs the charging process.

[0163] The control unit 20 acquires the detection signals S211, S212, S213 from the voltage detectors 11, 12, 13, and acquires the voltages V1, V2, V3 across the power storage devices C1, C2, C3 (ST41).

[0164] The control unit 20 determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST42), and if the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST42: No), the control unit 20 proceeds to step ST46, and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST42: Yes), the control unit 20 proceeds to step ST43.

[0165] In step ST43 (a state in which the charge states of the power storage devices C1 and C2 are unbalanced), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O1 and controls the third switch SW51 to be turned off. The control unit 20 then controls the switch element Q3 to be turned off and drives the switch elements Q1, Q2, and Q4 and the fourth switch SW1 to operate the DC-DC converter 10 in the charging mode and charge the power storage device C1 (time t31 in FIG. 16 ). At this time, the fourth switch SW1 functions as the switch element of the DC-DC converter 10 instead of the switch element Q3. The control unit 20 also controls the first switch SW13 to be turned off, the second switches SW11 and SW12 to be turned off, and the switches SW20 to SW23 to be turned off, thereby stopping the power supply to the loads 31 to 34. As the DCDC converter 10 charges the power storage device C1, the voltage V1 across the power storage device C1 increases, and the output voltage Vout gradually increases from the initial value Vint (time t31 to t32 in FIG. 16).

[0166] The control unit 20 sequentially determines whether the voltages V1 and V2 across the power storage devices C1 and C2 are the same (ST44), and if the voltages V1 and V2 across the power storage devices C1 and C2 are not the same (ST44: No), continues charging the power storage device C1 (ST43).

[0167] Thereafter, when the voltages V1 and V2 across the power storage devices C1 and C2 become the same (ST44: Yes), the control unit 20 turns off the fourth switch SW1 to stop charging of the power storage device C1 (ST45), and proceeds to step ST46. Time t32 in Fig. 16 is the timing when the voltages V1 and V2 across the power storage devices C1 and C2 become the same, and the voltage value of the output voltage Vout at this time is set to Vd1.

[0168] In step ST46, the control unit 20 determines whether the voltages V2 and V3 across the power storage devices C2 and C3 are the same. If the voltages V2 and V3 across the power storage devices C2 and C3 are the same (ST46: No), the control unit 20 proceeds to step ST50. If the voltages V2 and V3 across the power storage devices C2 and C3 are not the same (ST46: Yes), the control unit 20 proceeds to step ST47.

[0169] In step ST47 (a state in which the charge states of the power storage devices C2 and C3 are unbalanced), the control unit 20 connects the internal contact of the demultiplexer M1 to the output terminal O2 and controls the third switch SW51 to be turned off. The control unit 20 then controls the switch element Q3 to be turned off and drives the switch elements Q1, Q2, and Q4 and the fourth switch SW1 to operate the DC-DC converter 10 in the charging mode and charge the power storage devices C1 and C2 (time t33 in FIG. 16 ). At this time, the fourth switch SW1 functions as the switch element of the DC-DC converter 10 instead of the switch element Q3. The control unit 20 also controls the first switch SW13 to be turned off, the second switches SW11 and SW12 to be turned off, and the switches SW20 to SW23 to be turned off, thereby stopping the power supply to the loads 31 to 34. As the DCDC converter 10 charges the power storage devices C1, C2, the voltages V1, V2 across the power storage devices C1, C2 increase, and the output voltage Vout gradually increases from the voltage value Vd1 (times t33 to t34 in FIG. 16).

[0170] The control unit 20 sequentially determines whether the voltages V2 and V3 across the power storage devices C2 and C3 are the same (ST48), and if the voltages V2 and V3 across the power storage devices C2 and C3 are not the same (ST48: No), continues charging the power storage devices C1 and C2 (ST47).

[0171] Thereafter, when the voltages V2 and V3 across the power storage devices C2 and C3 become the same (ST48: Yes), the control unit 20 controls the fourth switch SW1 to be turned off to stop charging the power storage devices C1 and C2 (ST49), and proceeds to step ST50. Time point t34 in Fig. 16 is the timing when the voltages V2 and V3 across the power storage devices C2 and C3 become the same, that is, the timing when the charge states of the power storage devices C1, C2, and C3 are balanced, and the voltage value of the output voltage Vout at this time is set to Vd2.

[0172] In step ST50, the control unit 20 determines whether the output voltage Vout of the power storage module 40 is the maximum charging voltage Vp. If the output voltage Vout is the maximum charging voltage Vp (ST50: No), the charging process ends, and if the output voltage Vout is not the maximum charging voltage Vp (ST50: Yes), the process proceeds to step ST51.

[0173] In step ST51, the control unit 20 controls the third switch SW51 to be off and the fourth switch SW1 to be off, and drives the switch elements Q1 to Q4 to operate the DCDC converter 10 in the charging mode (time point t35 in FIG. 16 ), thereby charging the power storage devices C1, C2, and C3. As the charging of the power storage devices C1, C2, and C3 progresses, the voltages V1, V2, and V3 across the power storage devices C1, C2, and C3 increase, and the output voltage Vout gradually increases from the voltage value Vd2 at time point t35 (time points t35 to t36 in FIG. 16 ).

[0174] The control unit 20 sequentially determines whether the output voltage Vout of the storage module 40 is the maximum charging voltage Vp (ST52), and if the output voltage Vout is not the maximum charging voltage Vp (ST52: No), causes the DCDC converter 10 to continue charging the storage devices C1, C2, and C3 (ST51).

[0175] Thereafter, when the output voltage Vout reaches the maximum charging voltage Vp (ST52: Yes), the control unit 20 stops the operation of the DCDC converter 10 (ST53) and stops the charging process.

[0176] To summarize the above operations, in the backup power supply circuit device 1 of variant example 6, the control unit 20 determines whether to operate the DCDC converter 10 in a discharge mode in which the storage module 40 is discharged, or in a charge mode in which the storage module 40 is charged, based on a control command (the above-mentioned power supply no-requirement signal S1001) from an external system (external control device 1000).

[0177] In the discharge mode, the control unit 20 controls the demultiplexer M1 to connect a connection port between the Pth (P is an integer equal to or greater than 2 and less than N) power storage device CP counting from the low potential side among the N power storage devices C1 to C3 and the (P+1)th power storage device CP+1 to a discharge path PD11, and then compares the voltage of the (P+1)th power storage device CP with the voltage of the Pth power storage device CP. When the voltage of the power storage device CP+1 and the voltage of the power storage device CP become equal, the control unit 20 controls the demultiplexer M1 to connect a connection port between the Pth power storage device CP counting from the low potential side and the (P-1)th power storage device CP-1 to a discharge path PD11.

[0178] Furthermore, in the charging mode, the control unit 20 controls the demultiplexer M1 to connect the connection port between the Qth (Q is an integer equal to or greater than 1 and equal to or less than (N-2)) power storage device CQ counting from the low potential side and the (Q+1)th power storage device CQ+1 to the second charging path PA11, and while the fourth switch SW1 is operating as a switching element of the DCDC converter 10, the control unit 20 compares the voltage of the (Q+1)th power storage device CQ+1 with the voltage of the Qth power storage device CQ. When the voltages of the (Q+1)th power storage device CQ+1 and the voltage of the Qth power storage device CQ become equal, the control unit 20 controls the demultiplexer M1 to connect the connection port between the (Q+1)th power storage device CQ+1 and the (Q+2)th power storage device CQ+2 counting from the low potential side to the second charging path PA11, and the fourth switch SW1 is operated as a switching element of the DCDC converter 10.

[0179] In this way, when the control unit 20 operates the DCDC converter 10 in the discharge mode in response to a control command from an external system, the N power storage devices C1 to C3 are discharged, thereby suppressing deterioration of the N power storage devices C1 to C3. Furthermore, when the control unit 20 operates the DCDC converter 10 in the charge mode in response to a control command from an external system, the N power storage devices C1 to C3 can be fully charged in a state where any imbalance in the charge states of the N power storage devices C1 to C3 is eliminated, and the N power storage devices C1 to C3 can be prepared for power supply to the loads 31 to 34.

[0180] In Modification 6, the power storage module 40 includes three power storage devices C1 to C3, and two connection ports P1, P2 are provided between the three power storage devices C1 to C3, but the number of power storage devices included in the power storage module 40 may be two, or four or more. Also, in Modification 6, (N-1) connection ports P1, P2 are provided between the N power storage devices C1 to C3, but fewer than (N-1) connection ports may be provided between the N power storage devices C1 to C3.

[0181] (3.7) Modification 7 FIG. 17 is a schematic circuit diagram showing an example of the configuration of the backup power supply circuit device 1 according to Modification 7.

[0182] The seventh modification differs from the sixth modification in that the third switch SW51 includes a series circuit of a diode D61 and an insulated gate transistor Q51, and the fourth switch SW1 includes a series circuit of a diode D21 and an insulated gate transistor Q11.

[0183] The insulated gate transistor Q51 is realized by a MOSFET having a parasitic diode D51. The insulated gate transistor Q51 is individually controlled to be turned on or off by a control signal S51 input from the control unit 20 to the gate electrode.

[0184] The cathode of the diode D61 is connected to the drain electrode of the insulated gate transistor Q51, and the anode of the diode D61 is connected to the negative electrode of the DC power supply 2. The source electrode of the insulated gate transistor Q51 is connected to the common input terminal I1 of the demultiplexer M1.

[0185] The insulated gate transistor Q11 is realized by a MOSFET having a parasitic diode D11. The insulated gate transistor Q11 is individually controlled to be turned on or off by a control signal S11 input from the control unit 20 to the gate electrode.

[0186] The cathode of the diode D21 is connected to the drain electrode of the insulated gate transistor Q11, and the anode of the diode D21 is connected to the connection point of the switch elements Q3 and Q4. The source electrode of the insulated gate transistor Q11 is connected to the common input terminal I1 of the demultiplexer M1.

[0187] As described above, the third switch SW51 preferably includes a series circuit of a diode D61 and an insulated gate transistor Q51, and the fourth switch SW1 preferably includes a series circuit of a diode D21 and an insulated gate transistor Q11.

[0188] In the backup power supply circuit apparatus 1 according to the seventh modification, the diode D61 can prevent the power storage devices C1 and C2 from discharging via the discharge path PD11. The diode D21 can prevent the power storage devices C1 and C2 from discharging via the second charge path PA11. Furthermore, since the diodes D21 and D61 do not require a drive circuit, the configuration of the control unit 20 can be simplified.

[0189] In the seventh modification, the order of connection may be reversed since the diode D61 and the insulated gate transistor Q51 are connected in series. Also, the order of connection may be reversed since the diode D21 and the insulated gate transistor Q11 are connected in series.

[0190] Furthermore, in the seventh modification, similarly to the fifth modification, it is also preferable that the first switch SW13 and at least one of the M second switches SW11, SW12 include a series circuit of two MOS field effect transistors connected in series in opposite directions to each other.

[0191] (3.8) Modification 8 Fig. 18 is a schematic circuit diagram showing an example of the configuration of a backup power supply circuit device 1 according to Modification 8. Note that voltage detectors 11 to 13 are omitted from Fig. 18.

[0192] Modification 8 differs from Modification 6 in that the third switch SW51 includes a series circuit of two MOS field effect transistors (hereinafter abbreviated as MOSFETs) Q51, Q52 connected in series in opposite directions, and the fourth switch SW1 also differs from Modification 6 in that the fourth switch SW1 includes a series circuit of two MOSFETs Q11, Q12 connected in series in opposite directions.

[0193] More specifically, the third switch SW51 includes a common drain connection circuit of a MOSFET Q52 having a parasitic diode D52 and a MOSFET Q51 having a parasitic diode D51.

[0194] The fourth switch SW1 also includes a common drain connection circuit of a MOSFET Q11 having a parasitic diode D11 and a MOSFET Q12 having a parasitic diode D12.

[0195] MOSFETs Q51 and Q52 are controlled to be on or off in response to control signals S51 and S52 input to their gate electrodes from control unit 20. When discharging the charge of power storage device C3 or power storage devices C2 and C3 via discharge path PD11, control unit 20 controls MOSFETs Q51 and Q52 to be on.

[0196] The MOSFETs Q11 and Q12 are controlled to be on or off in response to control signals S11 and S12 input to their gate electrodes from the control unit 20. When charging the power storage device C1 or the power storage devices C1 and C2 via the second charging path PA11, the control unit 20 controls the MOSFETs Q11 and Q12 to be on.

[0197] In the eighth modification, the MOSFETs Q51 and Q52 can prevent the discharge of the power storage device C1 or the discharge of the power storage devices C1 and C2 via the discharge path PD11. In the eighth modification, the MOSFETs Q51 and Q52 with low on-resistance are used to prevent the discharge of the power storage device C1 or the power storage devices C1 and C2, so that the loss during discharge can be reduced compared to the configuration using the diode D61 as in the seventh modification.

[0198] Furthermore, in Modification 8, MOSFETs Q11 and Q12 can prevent discharging of the power storage device C1 or the power storage devices C1 and C2 via the second charging path PA11. In Modification 8, MOSFETs Q11 and Q12 with low on-resistance are used to prevent discharging of the power storage device C1 or the power storage devices C1 and C2, so that loss during charging can be reduced compared to the configuration in which diode D21 is used as in Modification 7.

[0199] 18, the third switch SW51 includes a common-drain connection circuit of two MOSFETs, but may include a common-source connection circuit of two MOSFETs. Also, in the circuit example shown in Fig. 18, the fourth switch SW1 includes a common-drain connection circuit of two MOSFETs, but may include a common-source connection circuit of two MOSFETs.

[0200] Furthermore, in the eighth modification, similarly to the fifth modification, it is also preferable that the first switch SW13 and at least one of the M second switches SW11, SW12 include a series circuit of two MOS field effect transistors connected in series in opposite directions to each other.

[0201] (3.9) Modification 9 Fig. 19 is a schematic circuit diagram of the control unit 20 provided in the backup power supply circuit device 1 according to Modification 9. Note that the configuration other than the control unit 20 is the same as the basic configuration, and therefore illustration and description thereof will be omitted.

[0202] The ninth modification differs from the basic configuration in that the control unit 20 controls the third switch SW51 to be on or off using control signals S1 to S4 output to the control electrodes of four switch elements Q1 to Q4.

[0203] The control unit 20 includes a control IC 200 that generates control signals S1 to S4 for the four switch elements Q1 to Q4 included in the DC-DC converter 10, two gate ICs 221 and 222, and a switching unit 210.

[0204] The gate ICs 221 and 222 are, for example, logic ICs with two inputs and one output.

[0205] A control signal S1 is input to a first input terminal of gate IC 221, and a switching signal is input to a second input terminal of gate IC 221 from switching unit 210. For example, when a switching signal with a high voltage level is input to the second input terminal of gate IC 221 from switching unit 210, gate IC 221 outputs the control signal S1 input to the first input terminal as control signal S151 to third switch SW51. For example, when a switching signal with a low voltage level is input to the second input terminal of gate IC 221 from switching unit 210, gate IC 221 does not output the control signal S1 input to the first input terminal.

[0206] A control signal S3 is input to a first input terminal of gate IC 222, and a switching signal is input to a second input terminal of gate IC 222 from switching unit 210. For example, when a switching signal with a high voltage level is input to the second input terminal of gate IC 222 from switching unit 210, gate IC 222 outputs the control signal S3 input to the first input terminal as control signal S151 to third switch SW51. For example, when a switching signal with a low level is input to the second input terminal of gate IC 222 from switching unit 210, gate IC 222 does not output the control signal S3 input to the first input terminal.

[0207] The output terminals of the gate ICs 221 and 222 are connected to the control electrode of the third switch SW51. The third switch SW51 is controlled to be turned on or off by a control signal S151 output from the gate IC 221 or 222.

[0208] If the DC-DC converter 10 performs a step-down operation when the third switch SW51 is controlled to be on and the charge of the power storage device C3 or the power storage devices C2 and C3 is discharged, the switch element Q1 is always on. In this case, the switching unit 210 outputs a switching signal with a high signal level to the gate IC 221 and outputs the control signal S1 to the third switch SW51 as the control signal S151, thereby controlling the third switch SW51 to be on.

[0209] Furthermore, if the DC-DC converter 10 performs a boost operation when the third switch SW51 is controlled to be on and the charge of the power storage device C3 or the power storage devices C2 and C3 is discharged, the switch element Q3 is always on. In this case, the switching unit 210 outputs a switching signal with a high signal level to the gate IC 222 and outputs the control signal S3 to the third switch SW51 as the control signal S151, thereby controlling the third switch SW51 to be on.

[0210] As described above, in the ninth modification, when the third switch SW51 is controlled to be on to allow a discharge current to flow, the control unit 20 controls the third switch SW51 to be on by utilizing the control signal of the switch element that is controlled to be on among the four switch elements Q1 to Q4. The control unit 20 can control the third switch SW51 to be on or off by utilizing the control signal S1 or S3 generated by the control IC 200, thereby simplifying the configuration of the control unit 20.

[0211] The circuit shown in FIG. 19 is an example, and the circuit configuration of the control unit 20 can be changed as appropriate.

[0212] (3.10) Modification 10 Fig. 20 is a schematic circuit diagram of the control unit 20 provided in the backup power supply circuit device 1 according to Modification 10. Note that the configuration other than the control unit 20 is the same as that of Modification 6, and therefore illustrations and descriptions thereof will be omitted.

[0213] The tenth modification differs from the sixth modification in that the control unit 20 controls the fourth switch SW1 using control signals S1 to S4 output to the control electrodes of the four switch elements Q1 to Q4.

[0214] The control unit 20 includes a control IC 200 that generates control signals S1 to S4 for the four switch elements Q1 to Q4 included in the DC-DC converter 10, two gate ICs 223 and 224, and a switching unit 210.

[0215] The gate ICs 223 and 224 are, for example, logic ICs with two inputs and one output.

[0216] A control signal S3 is input to a first input terminal of gate IC223, and a switching signal is input to a second input terminal of gate IC223 from switching unit 210. For example, when a switching signal with a high signal level is input to a second input terminal of gate IC223 from switching unit 210, gate IC223 outputs the control signal S3 input to the first input terminal to the control electrode of switch element Q3. For example, when a switching signal with a low signal level is input to the second input terminal of gate IC223 from switching unit 210, gate IC223 enters a state in which it does not output the control signal S3 input to the first input terminal.

[0217] A control signal S3 is input to a first input terminal of gate IC 224, and a switching signal is input to a second input terminal of gate IC 224 from switching unit 210. For example, when a switching signal with a high signal level is input to the second input terminal from switching unit 210, gate IC 224 outputs the control signal S3 input to the first input terminal as control signal S101. For example, when a switching signal with a low signal level is input to the second input terminal from switching unit 210, gate IC 224 enters a state in which it does not output the control signal S3 input to the first input terminal.

[0218] When charging the power storage devices C1 to C3 via the charging path (first charging path) PA1, the power storage devices C1 to C3 are charged by the DCDC converter 10 configured with the switching elements Q1 to Q4. Therefore, the switching unit 210 outputs a signal with a high voltage level to the gate IC 223 and a signal with a low voltage level to the gate IC 224, thereby causing the control signal S3 output from the control IC 200 to be output to the control electrode of the switching element Q3.

[0219] On the other hand, when charging the power storage device C1 or the power storage devices C1 and C2 via the second charging path PA11, the fourth switch SW1 functions as the switching element of the DCDC converter 10 instead of the switching element Q3, and the power storage device C1 or the power storage devices C1 and C2 are charged by the DCDC converter 10 configured with the switching elements Q1, Q2, and Q4 and the fourth switch SW2. Therefore, the switching unit 210 outputs a high-level signal to the gate IC 224 and a low-level signal to the gate IC 223, thereby outputting the control signal S3 output from the control IC 200 as the control signal S101 to the control electrode of the fourth switch SW1. As a result, the control IC 200 drives the switching elements Q1, Q2, and Q4 and the fourth switch SW1 to cause the DCDC converter 10 to perform a step-up operation or a step-down operation, thereby charging the power storage device C1 or the power storage devices C1 and C2 via the second charging path PA11.

[0220] In this way, when the control unit 20 having the control IC 200 flows a charging current through the second charging path PA11, it outputs a control signal S3 to the control electrode of the fourth switch SW1, which is output to the control electrode of the switch element Q3, which is one of the four switch elements Q1 to Q4 and is connected to the first charging path PA1, thereby causing the fourth switch SW1 to operate as a switch element of the DCDC converter 10.

[0221] In the tenth modification, the fourth switch SW1 can be controlled using the control signal S3 generated by the control IC 200, so that the configuration of the control unit 20 can be simplified.

[0222] The circuit shown in FIG. 20 is an example, and the circuit configuration of the control unit 20 can be changed as appropriate.

[0223] (3.11) Modification 11 Fig. 21 is a schematic circuit diagram of the control unit 20 provided in the backup power supply circuit device 1 according to Modification 11. Note that the configuration other than the control unit 20 is the same as that of Modification 6, and therefore illustrations and descriptions thereof will be omitted.

[0224] Variation 11 differs from variation 6 in that the control unit 20 includes a control IC 200 that generates control signals S1 to S4 for the four switch elements Q1 to Q4 of the DC-DC converter 10, and a distribution circuit 240.

[0225] For example, the distribution circuit 240 outputs the control signal S3 generated by the control IC 200 to the third switch SW51 and the fourth switch SW1 as control signals S151 and S101.

[0226] The distribution circuit 240 is made up of gate ICs 241 to 243 and a switching unit 210, as shown in FIG.

[0227] The gate ICs 241 to 243 are, for example, logic ICs with two inputs and one output.

[0228] A control signal S3 is input to first input terminals of gate ICs 241 to 243, and a switching signal is input to second input terminals of gate ICs 241 to 243 from switching unit 210. An output terminal of gate IC 241 is connected to the control electrode of switch element Q3. An output terminal of gate IC 242 is connected to the control electrode of fourth switch SW1. An output terminal of gate IC 243 is connected to the control electrode of third switch SW51.

[0229] Each of the gate ICs 241 to 243 outputs the control signal S3 input to the first input terminal when, for example, a switching signal with a high signal level is input to the second input terminal from the switching unit 210. Each of the gate ICs 241 to 243 enters a state in which it does not output the control signal S3 input to the first input terminal when, for example, a switching signal with a low signal level is input to the second input terminal from the switching unit 210.

[0230] When discharging the charge of the power storage device C2 or the power storage devices C2 and C3 via the discharge path PD11 in boost mode, the control unit 20 controls the switch element Q3 to be always on, and therefore outputs the control signal S3 to the third switch SW51 as the control signal S151 to control the third switch SW51 to be on, thereby discharging the charge of the power storage device C2 or the power storage devices C2 and C3 via the discharge path PD11.

[0231] When the DC-DC converter 10 performs a boost operation in the discharge mode, the switching unit 210 outputs a switching signal of a low signal level to the gate IC 242 to control the fourth switch SW1 to be turned off. The switching unit 210 also outputs a switching signal of a high signal level to the gate IC 241, and outputs the control signal S3 input from the control IC 200 to the switching element Q3 to operate the switching element Q3.

[0232] Furthermore, when the DC-DC converter 10 performs a boost operation in the discharge mode and discharges the power storage device C3 or the power storage devices C2 and C3 via the discharge path PD11, the control signal S3 becomes a high-level signal, and therefore the switching unit 210 outputs a switching signal of a high signal level to the gate IC 243. At this time, the control signal S3 is input as the control signal S151 to the control electrode of the third switch SW51, and therefore the third switch SW51 is turned on, and the power storage device C3 or the power storage devices C2 and C3 can be discharged via the discharge path PD11.

[0233] Furthermore, when the DC-DC converter 10 operates in the discharge mode and discharges the power storage devices C1, C2, and C3 via the discharge path PD1, the switching unit 210 outputs a switching signal with a high signal level to the gate IC 241 and outputs a switching signal with a low signal level to the gate ICs 242 and 243. At this time, the third switch SW51 is turned off, the fourth switch SW1 is turned off, and a control signal S3 is output to the control electrode of the switch element Q3. The control unit 20 drives the switch elements Q1 to Q4 to operate the DC-DC converter 10 and discharge the power storage devices C1, C2, and C3 via the discharge path PD1.

[0234] When the DC-DC converter 10 performs a step-down operation in the discharge mode and discharges the power storage device C3 or the power storage devices C2 and C3 via the discharge path PD11, the control signal S1 of the switch element Q1 becomes a high-level signal, and therefore the distribution circuit 240 may be configured to input the control signal S1 to the control electrode of the third switch SW51. At this time, the third switch SW51 is turned on, and the power storage device C3 or the power storage devices C2 and C3 can be discharged via the discharge path PD11.

[0235] On the other hand, when the DC-DC converter 10 operates in the charging mode, the switching unit 210 outputs a low-level switching signal to the gate IC 243 to control the third switch SW51 to be turned off.

[0236] When charging the power storage devices C1, C2, and C3 via the first charging path PA1 in the charging mode, the switching unit 210 outputs a switching signal of a high signal level to the gate IC 241 and a switching signal of a low signal level to the gate IC 242, controls the fourth switch SW1 to be turned off, and outputs a control signal S3 to the control electrode of the switching element Q3. At this time, the control unit 20 drives the switching elements Q1 to Q4, so that the power storage devices C1, C2, and C3 are charged by the DCDC converter 10.

[0237] When charging the power storage device C1 or the power storage devices C1 and C2 via the second charging path PA11 in the charging mode, the switching unit 210 outputs a switching signal of a high signal level to the gate IC 242 and a switching signal of a low signal level to the gate IC 241, controls the switch element Q3 to be turned off, and outputs a control signal S3 to the control electrode of the fourth switch SW1. At this time, the control unit 20 drives the switch elements Q1, Q2, Q4 and the fourth switch SW1 to operate the DCDC converter 10, and causes the DCDC converter 10 to charge the power storage device C1 or the power storage devices C1 and C2.

[0238] In this way, when the control unit 20 including the distribution circuit 240 flows a charging current through the second charging path PA11, it outputs a control signal S3 to the control electrode of the fourth switch SW1, which is output to the control electrode of the switch element Q3, which is one of the four switch elements Q1 to Q4 and is connected to the first charging path PA1, and causes the fourth switch SW1 to operate as a switch element of the DCDC converter 10.

[0239] This allows the control unit 20 to drive the fourth switch SW1 using the control signal S3 generated by the control IC 200, thereby simplifying the configuration of the control unit 20. In addition, in the eleventh modification, the control unit 20 can drive the third switch SW51 and the fourth switch SW1 using the control signal S3 generated by the control IC 200, thereby further simplifying the configuration of the control unit 20.

[0240] 21 and 22 are merely examples, and the circuit configuration of the control unit 20 can be changed as appropriate.

[0241] (3.12) Other Modifications In the basic configuration and each modification, the DC power supply 2 may be, for example, a secondary battery such as a lead battery or a lithium ion battery, or a DC power supply circuit such as a DC-DC converter.

[0242] In the basic configuration and each modified example, four loads 31 to 34 are connected between the first output terminals T3 and T4, but the number of loads may be one or more, and the number of loads can be changed as appropriate.

[0243] In the basic configuration and each variant example, the loads 31 to 34 may be, for example, electrical equipment that operates on a DC power source, a secondary battery such as a lead battery or a lithium ion battery, or a DC power supply circuit such as a DCDC converter.

[0244] In the basic configuration and each of the modified examples, the power storage devices C1 to C3 are not limited to capacitors, but may be other power storage cells such as secondary batteries, such as lithium ion batteries.

[0245] In the basic configuration and each modified example, MOSFETs are used as the switch elements Q1 to Q4, but the present disclosure is not limited to this, and other switch elements such as IGBTs (Insulated Gate Bipolar Transistors) may also be used.

[0246] In the basic configuration and each modified example, the DC-DC converter 10 is configured using switch elements Q1 to Q4, but the present disclosure is not limited to this, and the converter may be configured by connecting a plurality of MOSFETs in series or in parallel.

[0247] In the basic configuration and each modified example, the DC-DC converter 10 is a converter that can step up and down in both charging and discharging directions, but the present disclosure is not limited to this, and for example, a DC-DC converter that can only step down when charging and only step up when discharging may be used.

[0248] In the basic configuration and each of the modified examples, the backup power supply circuit device 1 is configured using one DC-DC converter 10, but the present disclosure is not limited to this, and a configuration using a plurality of DC-DC converters 10 may also be used.

[0249] In the basic configuration and each modified example, multiple connection ports P1 to P3 are connected to the first output terminal T3 via second switches SW11, SW12 and a first switch SW13, but each of the multiple connection ports P1 to P3 may be connected to a separate load via a switch.

[0250] In the basic configuration and each of the modified examples, the configuration of the connection circuit that connects each of the multiple connection ports P1 to P3 to at least one of the multiple loads can be changed as appropriate.

[0251] In the basic configuration and each of the modified examples, the backup power supply circuit device 1 is described as being mounted on an automobile, but the backup power supply circuit device 1 may also be mounted on a moving object such as an airplane, a ship, or a train. Furthermore, the backup power supply circuit device 1 is not limited to being mounted on a moving object, but may also be installed and used in a facility or the like.

[0252] (Summary) The above-described embodiments and the like disclose the following aspects.

[0253] A backup power supply circuit device (1) of a first aspect includes a power storage module (40), a DC-DC converter (10), a charging path (PA1), a first power supply path (PB1), a first switch (SW13), M connection ports (P1 to P3), a discharging path (PD11), a demultiplexer (M1), M second power supply paths (PB11, PB12), M second switches (SW11, SW12), and a third switch (SW51). N is an integer equal to or greater than 2, and M is an integer equal to or greater than 1 and less than N. The power storage module (40) includes a series circuit of N power storage devices (C1 to C3) connected in series. The DC-DC converter (10) is connected between a DC power source (2) and the power storage module (40) and is capable of bidirectional step-up and step-down operation. The charging path (PA1) connects a series circuit of N power storage devices (C1 to C3) between output terminals of the DC-DC converter (10) and supplies charging current to the N power storage devices (C1 to C3). The first power supply path (PB1) connects the power storage module (40) and loads (31 to 34). The first switch (SW13) is inserted in the first power supply path (PB1) and switches whether or not the power storage module (40) and the loads (31 to 34) are connected. The M connection ports (P1 to P3) are connected to M connection points out of (N-1) connection points provided between the N power storage devices (C1 to C3). The discharging path (PD11) flows a discharging current from the power storage module (40) via the DC-DC converter (10). The demultiplexer (M1) has a common input terminal (I1) connected to the discharge path (PD11) and a plurality of output terminals including M output terminals (O1, O2) connected to M connection ports (P1, P2). M second power supply paths (PB11, PB12) connect the M connection ports (P1, P2) to the loads (31 to 34). M second switches (SW11, SW12) are inserted into the M second power supply paths (PB11, PB12) and respectively switch between connecting and disconnecting the M connection ports (P1, P2) to the loads (31 to 34). A third switch (SW51) is inserted into the discharge path (PD11) and switches between connecting and disconnecting the DCDC converter (10) and the common input terminal (I1) of the demultiplexer (M1).

[0254] According to this aspect, it is possible to provide a backup power supply circuit device (1) that can effectively utilize the remaining charge of the N power storage devices (C1 to C3) while eliminating imbalances in the charge states of the N power storage devices (C1 to C3).

[0255] The backup power supply circuit device (1) of the second aspect is the same as that of the first aspect, and further includes voltage detectors (11 to 13) that detect the voltages of the N power storage devices (C1 to C3) and a control unit (20) that controls the demultiplexer (M1). In a state in which the control unit (20) controls the demultiplexer (M1) to connect the connection ports (P1, P2) between the P-th power storage device (C1 to C3) and the (P+1)-th power storage device (C1 to C3) counting from the low potential side to the discharge path (PD11), when the voltage of the (P+1)-th power storage device (C1 to C3) becomes equal to the voltage of the P-th power storage device (C1 to C3), the control unit (20) controls the demultiplexer (M1) to connect the connection ports (P1, P2) between the P-th power storage device (C1 to C3) and the (P-1)-th power storage device (C1 to C3) counting from the low potential side to the discharge path (PD11), where P is an integer equal to or greater than 2 and less than N.

[0256] According to this aspect, it is possible to eliminate imbalances in the charge states of the N power storage devices (C1 to C3) while effectively utilizing the remaining amounts of charge in the N power storage devices (C1 to C3).

[0257] In the backup power supply circuit device (1) of the third aspect, in the second aspect, the control unit (20) causes a discharge current to flow through the discharge path (PD11), and when the voltages of the N power storage devices (C1 to C3) become the same voltage, the control unit (20) controls the third switch (SW51) to be turned off, and then causes the DCDC converter (10) to charge the N power storage devices (C1 to C3).

[0258] According to this aspect, after eliminating the imbalance in the charge states of the N power storage devices (C1 to C3), the N power storage devices (C1 to C3) can be charged in preparation for supplying power to the loads (31 to 34).

[0259] In the backup power supply circuit device (1) of the fourth aspect, in the second or third aspect, the control unit (20) controls a switch selected from the first switch (SW13) and the M number of second switches (SW11, SW12) to be on, thereby supplying power from the storage module (40) to the loads (31 to 34).

[0260] According to this aspect, by supplying power from the storage module (40) to the loads (31 to 34), the time until power supply begins can be shortened compared to when power is supplied from the DC-DC converter (10) to the loads (31 to 34).

[0261] In a backup power supply circuit device (1) of a fifth aspect, in any one of the first to fourth aspects, the charging path (PA1) is the first charging path (PA1). The backup power supply circuit device (1) further includes a second charging path (PA11) and a fourth switch (SW1). The second charging path (PA11) connects the common input terminal (I1) of the demultiplexer (M1) to the DCDC converter (10) to allow a charging current to flow from the DCDC converter (10) to the storage module (40). The fourth switch (SW1) is inserted in the second charging path (PA11) and switches whether or not the DCDC converter (10) and the common input terminal (I1) are connected.

[0262] According to this aspect, by charging the storage module (40) via the second charging path (PA11) and the demultiplexer (M1), it is possible to eliminate imbalances in the charge states of the N storage devices (C1 to C3).

[0263] The backup power supply circuit device (1) of a sixth aspect is the fifth aspect, further comprising voltage detectors (11-13) that detect the voltages of the N power storage devices (C1-C3) and a control unit (20) that controls the demultiplexer (M1). The control unit (20) determines, based on a control command from an external system, whether to operate the DCDC converter (10) in a discharge mode that discharges the power storage module (40) or in a charge mode that charges the power storage module (40). In the discharge mode, while the control unit (20) controls the demultiplexer (M1) to connect the connection ports (P1, P2) between the P-th power storage device (C1 to C3) and the (P+1)-th power storage device (C1 to C3) counting from the low potential side to the discharge path (PD11), when the voltage of the (P+1)-th power storage device (C1 to C3) becomes equal to the voltage of the P-th power storage device (C1 to C3), the control unit (20) controls the demultiplexer (M1) to connect the connection ports (P1, P2) between the P-th power storage device (C1 to C3) and the (P-1)-th power storage device (C1 to C3) counting from the low potential side to the discharge path (PD11), where P is an integer equal to or greater than 2 and less than N. In the charging mode, while the control unit (20) controls the demultiplexer (M1) to connect the connection ports (P1, P2) between the Qth power storage device (C1 to C3) and the (Q+1)th power storage device (C1 to C3) counting from the low potential side to the second charging path (PA11), when the voltage of the (Q+1)th power storage device (C1 to C3) becomes equal to the voltage of the Qth power storage device (C1 to C3), the control unit (20) controls the demultiplexer (M1) to connect the connection ports (P1, P2) between the (Q+1)th power storage device (C1 to C3) and the (Q+2)th power storage device (C1 to C3) counting from the low potential side to the second charging path (PA11), where Q is an integer equal to or greater than 1 and equal to or less than (N-2).

[0264] According to this aspect, when the control unit (20) operates the DCDC converter (10) in a discharge mode in response to a control command from an external system, the N power storage devices (C1 to C3) are discharged, thereby suppressing deterioration of the N power storage devices (C1 to C3). Also, when the control unit (20) operates the DCDC converter (10) in a charge mode in response to a control command from the external system, the N power storage devices (C1 to C3) are charged in a state where the imbalance in the charge states of the N power storage devices (C1 to C3) is eliminated, and the N power storage devices (C1 to C3) are prepared for power supply to the loads (31 to 34).

[0265] In the backup power supply circuit device (1) of the seventh aspect, in any one of the first to sixth aspects, the third switch (SW51) includes a series circuit of a diode (D61) and an insulated gate transistor (Q51).

[0266] According to this aspect, it is possible to suppress the flow of discharge current from the storage devices (C1 to C3) through the third switch (SW51), and since the diode (D61) does not need to be controlled, there is an advantage in that the configuration of the control unit (20) can be simplified.

[0267] In the backup power supply circuit device (1) of the eighth aspect, in any one of the first to sixth aspects, the third switch (SW51) includes a series circuit of two MOS field effect transistors (Q51, Q52) connected in series in opposite directions to each other.

[0268] According to this aspect, it is possible to suppress the flow of discharge current from the power storage device (C1 to C3) through the third switch (SW51), and since the MOS field effect transistors (Q51, Q52) have a smaller on-resistance than the diode (D61), it is possible to reduce losses.

[0269] In the backup power supply circuit device (1) of the ninth aspect, in the fifth or sixth aspect, the fourth switch (SW1) includes a series circuit of a diode (D21) and an insulated gate transistor (Q11).

[0270] According to this aspect, it is possible to suppress the flow of discharge current from the storage devices (C1 to C3) through the fourth switch (SW1), and since the diode (D21) does not need to be controlled, there is an advantage in that the configuration of the control unit (20) can be simplified.

[0271] In the backup power supply circuit device (1) of the tenth aspect, in the fifth or sixth aspect, the fourth switch (SW1) includes a series circuit of two MOS field effect transistors (Q11, Q12) connected in series in opposite directions to each other.

[0272] According to this aspect, it is possible to suppress the flow of discharge current from the power storage device (C1 to C3) through the fourth switch (SW1), and since the MOS field effect transistors (Q11, Q12) have a smaller on-resistance than the diode (D21), it is possible to reduce losses.

[0273] In the backup power supply circuit device (1) of the eleventh aspect, in any one of the first to tenth aspects, at least one of the first switch (SW13) and the M second switches (SW11, SW12) includes a series circuit of two MOS field effect transistors (Q31 to Q36) connected in series in opposite directions to each other.

[0274] According to this aspect, it is possible to reduce the possibility that the charge in the power storage devices (C1 to C3) is discharged via the first switch (SW13) and the M second switches (SW11, SW12).

[0275] In a backup power supply circuit device (1) of a twelfth aspect, in any one of the first to eleventh aspects, the DC-DC converter (10) includes an H-bridge type step-up / step-down converter circuit having four switch elements (Q1 to Q4). The backup power supply circuit device (1) further includes a control unit (20) that outputs control signals to the control electrodes of each of the four switch elements (Q1 to Q4) to individually control the four switch elements (Q1 to Q4) to turn on or off. The control unit (20) controls a third switch (SW51) to turn on or off using the control signals output to the control electrodes of the four switch elements (Q1 to Q4).

[0276] According to this aspect, the configuration of the control unit (20) can be simplified.

[0277] In the backup power supply circuit device (1) of the thirteenth aspect, when the third switch (SW51) is controlled to be on to allow a discharge current to flow in the twelfth aspect, the control unit (20) controls the third switch (SW51) to be on by utilizing the control signal of the switch element (Q1 to Q4) that is controlled to be on among the four switch elements (Q1 to Q4).

[0278] According to this aspect, the configuration of the control unit (20) can be simplified.

[0279] A backup power supply circuit device (1) of a fourteenth aspect is any one of the fifth, sixth, ninth, and tenth aspects, in which the DC-DC converter (10) includes an H-bridge type step-up / step-down converter circuit having four switch elements (Q1 to Q4). The backup power supply circuit device (1) further includes a control unit (20) that outputs control signals to the control electrodes of each of the four switch elements (Q1 to Q4) to individually control the four switch elements (Q1 to Q4) to turn them on or off. The control unit (20) controls a fourth switch (SW1) using the control signals output to the control electrodes of the four switch elements (Q1 to Q4).

[0280] According to this aspect, the configuration of the control unit (20) can be simplified.

[0281] In the backup power supply circuit device (1) of the fifteenth aspect, in the fourteenth aspect, when a charging current is caused to flow through the second charging path (PA11), the control unit (20) outputs a control signal to the control electrode of the fourth switch (SW1), the control signal being output to the control electrode of the switch element (Q3) connected to the first charging path (PA1) among the four switch elements (Q1 to Q4). As a result, the control unit (20) causes the fourth switch (SW1) to operate as a switch element of the DCDC converter (10).

[0282] According to this aspect, the configuration of the control unit (20) can be simplified.

[0283] The configurations according to the second to fifteenth aspects are not essential for the backup power supply circuit device (1) and can be omitted as appropriate.

[0284] As described above in detail, the backup power supply circuit apparatus 1 according to the present disclosure can effectively utilize the stored energy capacities of the power storage devices C1 to C3 while eliminating imbalances in the charge states that occur in the power storage devices C1 to C3.

[0285] 1 Backup power supply circuit device 2 DC power supply 10 DCDC converter 11 to 13 Voltage detector 20 Control unit 31 to 34 Load 40 Storage module C1 to C3 Storage device D21, D61 Diode I1 Common input terminal M1 Demultiplexer O1, O2 Output terminal P1 to P3 Connection port PA1 Charging path (first charging path) PA11 Second charging path PB1 First power supply path PB11, PB12 Second power supply path PD1, PD11 Discharging path Q1 to Q4 Switching elements Q11, Q12, Q51, Q52 Insulated gate transistor (MOS field effect transistor) Q31 to Q36 MOS field effect transistor SW1 Fourth switch SW11, SW12 Second switch SW13 First switch SW51 Third switch

Claims

1. A power storage module including a series circuit of N power storage devices (N is an integer of 2 or more) connected in series; a DC-DC converter capable of bidirectional step-up and step-down operation connected between a DC power source and the power storage module; a charging path connecting the series circuit of the N power storage devices between output terminals of the DC-DC converter to supply a charging current to the N power storage devices; a first power supply path connecting the power storage module and a load; a first switch inserted in the first power supply path and switching whether or not to connect the power storage module and the load; M connection ports connected to M connection points (M is an integer of 1 or more and less than N) out of (N-1) connection points provided between the N power storage devices; a discharge path for flowing a discharge current from the power storage module through the DC-DC converter; a demultiplexer having a common input terminal connected to the discharge path and a plurality of output terminals including M output terminals connected to the M connection ports; and M second power supply paths connecting the M connection ports and the load. a second switch inserted in the M second power supply paths, each of the second switches switching whether or not to connect the M connection ports to the load; and a third switch inserted in the discharge path, each of the second switches switching whether or not to connect the DCDC converter to the common input terminal of the demultiplexer.

2. A backup power supply circuit device as claimed in claim 1, further comprising: a voltage detector which detects the voltage of each of the N power storage devices; and a control unit which controls the demultiplexer, wherein in a state in which the control unit controls the demultiplexer to connect a connection port between a Pth power storage device (P is an integer equal to or greater than 2 and less than N) counting from the low potential side and a (P+1)th power storage device to the discharge path, when the voltage of the (P+1)th power storage device and the voltage of the Pth power storage device become equal, the control unit controls the demultiplexer to connect the connection port between the Pth power storage device and the (P-1)th power storage device counting from the low potential side to the discharge path.

3. The backup power supply circuit apparatus according to claim 2, wherein the control unit controls the third switch to be turned off when the voltages of the N power storage devices become the same voltage by flowing a discharge current through the discharge path, and then causes the DCDC converter to charge the N power storage devices.

4. The backup power supply circuit device according to claim 2 or 3, wherein the control unit supplies power from the storage module to the load by controlling to turn on the first switch and a switch selected from the M second switches.

5. The backup power supply circuit device according to any one of claims 1 to 4, wherein the charging path is a first charging path, and further comprising: a second charging path connecting the common input terminal of the demultiplexer and the DCDC converter to allow a charging current to flow from the DCDC converter to the storage module; and a fourth switch inserted in the second charging path for switching whether or not to connect between the DCDC converter and the common input terminal.

6. The power supply device further includes a voltage detector that detects the voltage of each of the N power storage devices, and a control unit that controls the demultiplexer, wherein the control unit determines, based on a control command from an external system, whether to operate the DCDC converter in a discharge mode in which the power storage module is discharged, or in a charge mode in which the power storage module is charged, and in the discharge mode, when the control unit controls the demultiplexer to connect a connection port between a Pth power storage device (P is an integer equal to or greater than 2 and less than N) counting from a low potential side and a (P+1)th power storage device to the discharge path, and when the voltage of the (P+1)th power storage device and the voltage of the Pth power storage device become equal, the control unit controls the demultiplexer to connect a connection port between the Pth power storage device and the (P-1)th power storage device counting from a low potential side to the discharge path, 6. The backup power supply circuit device according to claim 5, wherein in the charging mode, when the control unit controls the demultiplexer to connect a connection port between a Qth (Q is an integer greater than or equal to 1 and less than or equal to (N-2)) power storage device counting from a low potential side and a (Q+1)th power storage device to the second charging path, when a voltage of the (Q+1)th power storage device and a voltage of the Qth power storage device become equal, the control unit controls the demultiplexer to connect a connection port between the (Q+1)th power storage device and the (Q+2)th power storage device counting from a low potential side to the second charging path.

7. The backup power supply circuit device according to any one of claims 1 to 6, wherein the third switch includes a series circuit of a diode and an insulated gate transistor.

8. The backup power supply circuit device according to any one of claims 1 to 6, wherein the third switch includes a series circuit of two MOS field effect transistors connected in series in opposite directions to each other.

9. The backup power supply circuit device according to claim 5 or 6, wherein the fourth switch includes a series circuit of a diode and an insulated gate transistor.

10. The backup power supply circuit device according to claim 5 or 6, wherein the fourth switch includes a series circuit of two MOS field effect transistors connected in series in opposite directions to each other.

11. The backup power supply circuit device according to any one of claims 1 to 10, wherein at least one of the first switch and the M second switches includes a series circuit of two MOS field effect transistors connected in series in opposite directions to each other.

12. The backup power supply circuit device according to any one of claims 1 to 11, wherein the DCDC converter includes an H-bridge type buck-boost converter circuit having four switch elements, and further includes a control unit that outputs a control signal to a control electrode of each of the four switch elements to individually control the four switch elements to be on or off, and the control unit controls the third switch to be on or off by utilizing the control signal output to the control electrodes of the four switch elements.

13. The backup power supply circuit device according to claim 12, wherein, when the third switch is controlled to be on to allow a discharge current to flow, the control unit controls the third switch to be on by utilizing a control signal of a switch element that is controlled to be on among the four switch elements.

14. The backup power supply circuit device according to any one of claims 5, 6, 9 and 10, wherein the DCDC converter includes an H-bridge type buck-boost converter circuit having four switch elements, and further includes a control unit that outputs a control signal to a control electrode of each of the four switch elements to individually control the four switch elements to be on or off, and the control unit controls the fourth switch by utilizing the control signal output to the control electrodes of the four switch elements.

15. The backup power supply circuit device according to claim 14, wherein when a charging current is caused to flow through the second charging path, the control unit outputs a control signal to a control electrode of a switch element among the four switch elements that is connected to the first charging path, to the control electrode of the fourth switch, thereby causing the fourth switch to operate as the switch element of the DCDC converter.

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