Power supply system and control method for power supply system

Abstract

A power supply system according to the present invention comprises a power supply terminal, a load terminal, and a backup power supply unit. The power supply terminal is connected to a power supply. The load terminal is connected to a load. The backup power supply unit is connected to a power supply path. The power supply path connects the power supply terminal and the load terminal. The backup power supply unit includes a power storage unit and a power conversion unit. The power conversion unit is connected between the power storage unit and the power supply path. When the power supply has failed, the power conversion unit supplies regenerative power generated by the load via the power conversion unit to the power storage unit.

Description

Power supply system and control method for power supply system

[0001] The present disclosure relates to a power supply system and a control method for a power supply system, and more particularly to a power supply system including a backup power supply unit and a control method for a power supply system.

[0002] Patent Document 1 discloses an in-vehicle power supply system. The in-vehicle power supply system of Patent Document 1 includes a power supply unit (power source), a power storage unit, and a backup circuit. The backup circuit is configured to supply power from the power storage unit when the power supply unit fails.

[0003] JP 2019-193493 A

[0004] A power supply system according to one aspect of the present disclosure includes a power supply terminal, a load terminal, and a backup power supply unit. The power supply terminal is connected to a power supply. The load terminal is connected to a load. The backup power supply unit is connected to a power supply path. The power supply path connects the power supply terminal and the load terminal. The backup power supply unit includes a power storage unit and a power conversion unit. The power conversion unit is connected between the power storage unit and the power supply path. When the power supply fails, the power conversion unit supplies regenerative power generated in the load to the power storage unit via the power conversion unit.

[0005] In a control method for a power supply system according to one aspect of the present disclosure, the power supply system includes a power supply terminal, a load terminal, and a backup power supply unit. The power supply terminal is connected to a power supply. The load terminal is connected to a load. The backup power supply unit is connected to a power supply path. The power supply path connects the power supply terminal and the load terminal. The backup power supply unit includes a power storage unit and a power conversion unit. The power conversion unit is connected between the power storage unit and the power supply path. In the control method for the power supply system, when the power supply fails, the power conversion unit is controlled so that regenerative power generated in the load is supplied to the power storage unit via the power conversion unit.

[0006] According to the power supply system and the control method for the power supply system according to the above aspects, it is possible to effectively utilize regenerative power even in a state where the power supply fails.

[0007] FIG. 1 is a block diagram of a power supply system according to a first embodiment. FIG. 2 is a circuit diagram showing the inside of a power storage unit in the power supply system according to the first embodiment. FIG. 3 is a flowchart showing the operation of a control unit in the power supply system according to the first embodiment. FIG. 4 is a schematic diagram showing the operation of a power supply system according to a modified example of the first embodiment. FIG. 5 is a block diagram of a power supply system according to a second embodiment. FIG. 6 is a schematic diagram showing the operation of the power supply system according to the second embodiment when there is no power supply failure. FIG. 7 is a schematic diagram showing the operation of the power supply system according to the second embodiment when there is a power supply failure.

[0008] In the in-vehicle power supply system disclosed in Patent Document 1, even if regenerative power is generated in the load when the power supply unit fails, the regenerative power cannot be supplied as charging power to the failed power supply unit, and therefore there is a possibility that the regenerative power may affect the operation of the backup circuit.

[0009] The present disclosure provides a power supply system and a control method for a power supply system that can effectively utilize regenerative power when the power supply fails.

[0010] Hereinafter, a power supply system and a control method for a power supply system according to an embodiment will be described in detail with reference to the drawings. However, each diagram described in the following embodiments is a schematic diagram, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Note that 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.

[0011] (Embodiment 1) (1) Configuration As shown in Fig. 1, a power supply system 1 according to embodiment 1 is connected between a power supply 2 and a load 3. The power supply system 1 is used in, for example, a mobile object including a vehicle such as an automobile or an electric motorcycle.

[0012] The power supply 2 is the main power supply of the mobile body and is, for example, a rechargeable secondary battery such as a lithium ion battery. The load 3 is, for example, an electric motor for driving an electric brake or an electric shift of the mobile body.

[0013] 1, the power supply system 1 includes a first terminal Ta1 and a second terminal Ta2. The first terminal Ta1 corresponds to a power supply terminal in the present disclosure. The second terminal Ta2 corresponds to a load terminal in the present disclosure.

[0014] The first terminal Ta1 is connected to a power supply 2. More specifically, the positive electrode of the power supply 2 is connected to the first terminal Ta1, and the negative electrode of the power supply 2 is connected to a ground electrode (not shown).

[0015] The second terminal Ta2 is connected to the load 3. More specifically, the positive side of the power receiving terminal of the load 3 is connected to the second terminal Ta2, and the negative side of the power receiving terminal of the load 3 is connected to the ground electrode.

[0016] As shown in Fig. 1, the power supply system 1 includes a backup power supply unit 10. The backup power supply unit 10 is connected to a power supply path R1 that connects a first terminal Ta1 and a second terminal Ta2. More specifically, the positive electrode side of the backup power supply unit 10 is connected to a third terminal Ta3 that is disposed on the power supply path R1. The negative electrode side of the backup power supply unit 10 is connected to a ground electrode.

[0017] The backup power supply unit 10 includes a power storage unit 11 , a power conversion unit 12 , and a control unit 13 .

[0018] The power storage unit 11 stores power supplied from the power source 2 and supplies the stored power to the load 3. As shown in FIG. 2 , the power storage unit 11 includes, for example, a plurality of (eight in FIG. 2 ) electric double layer capacitors (EDLCs) C1. The electric double layer capacitors C1 are devices capable of rapid charging and discharging. More specifically, the power storage unit 11 includes a plurality of (two in FIG. 2 ) circuits in which a plurality of (four in FIG. 2 ) unit cells are connected in series, with each of the plurality of electric double layer capacitors C1 serving as a unit cell.

[0019] As shown in FIG. 2 , the power storage unit 11 has a first terminal Tb1 and a second terminal Tb2. The first terminal Tb1 is connected to an initial-stage electric double layer capacitor C11. Here, the "initial-stage electric double layer capacitor C11" refers to an electric double layer capacitor C11 whose positive electrode is not connected to the negative electrode of any other electric double layer capacitor C1 in a series circuit including multiple electric double layer capacitors C1. The second terminal Tb2 is connected to a final-stage electric double layer capacitor C12. Here, the "final-stage electric double layer capacitor C12" refers to an electric double layer capacitor C12 whose negative electrode is not connected to the positive electrode of any other electric double layer capacitor C1 in a series circuit including multiple electric double layer capacitors C1. That is, the first terminal Tb1 is connected to one end on the positive side of the circuit in which multiple electric double layer capacitors C1 are connected in series, and the second terminal Tb2 is connected to one end on the negative side of the circuit in which multiple electric double layer capacitors C1 are connected in series. 1, the first end Tb1 of the power storage unit 11 is connected to the third terminal Ta3 via the power conversion unit 12. The first end Tb1 of the power storage unit 11 is connected to the ground electrode.

[0020] The power conversion unit 12 is connected between the power storage unit 11 and the power supply path R1. More specifically, a first end of the power conversion unit 12 is connected to the third terminal Ta3. A second end of the power conversion unit 12 is connected to the first end Tb1 of the power storage unit 11.

[0021] The power conversion unit 12 controls charging and discharging of the power storage unit 11. Under the control of the control unit 13, the power conversion unit 12 performs one of charging control, which charges the power storage unit 11 from the power supply path R1, and discharging control, which discharges the power storage unit 11 to the power supply path R1. In the case of charging control, the power conversion unit 12 supplies power from the power supply path R1 to the power storage unit 11 via the power conversion unit 12. Here, power is supplied to the power supply path R1 from a power source 2 that is not faulty and from a load 3 that is generating regenerative power. In other words, when the power source 2 fails, the power conversion unit 12 supplies regenerative power generated in the load 3 to the power storage unit 11 via the power conversion unit 12. In the case of discharging control, the power conversion unit 12 supplies power from the power storage unit 11 to the power supply path R1 via the power conversion unit 12.

[0022] For example, in charging control, the power conversion unit 12 boosts the power received from the power supply path R1 and supplies the boosted power to the power storage unit 11. That is, the voltage Va4 at the first end Tb1 of the power storage unit 11 is higher than the voltage Va3 at the third terminal Ta3. The power conversion unit 12 includes a charging path including, for example, a boost circuit including a capacitor and multiple switch elements, and a diode connected in series with the boost circuit. The forward direction of the diode is from the power supply path R1 toward the first end Tb1 of the power storage unit 11.

[0023] Furthermore, for example, in the discharge control, the power conversion unit 12 steps down the power received from the power storage unit 11 and supplies the power to the power supply path R1. That is, the voltage Va3 at the third terminal Ta3 is lower than the voltage Va4 at the first end Tb1 of the power storage unit 11. The power conversion unit 12 includes a discharge path including, for example, a step-down circuit including a capacitor and multiple switch elements, and a diode connected in series with the step-down circuit. The forward direction of the diode is from the first end Tb1 of the power storage unit 11 toward the power supply path R1.

[0024] The control unit 13 includes, for example, a computer system having a processor and a memory. The processor executes a program stored in the memory, causing the computer system to function as the control unit 13. The program executed by the processor is pre-recorded in the memory of the computer system here, but may also be provided by being recorded on a non-transitory recording medium such as a memory card, or may be provided via a telecommunications line such as the Internet.

[0025] The control unit 13 controls the operation of the power conversion unit 12 based on whether or not the power supply 2 has failed and whether or not regenerative power is being generated from the load 3. Here, a state in which the power supply 2 has failed refers to a state in which power cannot be normally supplied from the power supply 2 to the power supply system 1 and from the power supply 2 to the load 3 via the power supply system 1. Examples of a state in which the power supply 2 has failed include a state in which the electromotive force of the power supply 2 is less than a threshold value, or a state in which there is no electrical continuity between the first terminal Ta1 and the positive electrode of the power supply 2.

[0026] The control unit 13 monitors, for example, the voltage Va1 at the first terminal Ta1, the voltage Va2 at the second terminal Ta2, and the voltage Va3 at the third terminal Ta3. The control unit 13 determines whether the power supply 2 has failed and whether regenerative power is being generated from the load 3 based on, for example, the respective values ​​of the voltage Va1 at the first terminal Ta1, the voltage Va2 at the second terminal Ta2, and the voltage Va3 at the third terminal Ta3 and the difference between these values. For example, the control unit 13 determines that the power supply 2 has failed when the voltage Va1 is less than a threshold and the voltage Va2 is less than a threshold. Once the control unit 13 determines that the power supply 2 has failed, it maintains its determination that the power supply 2 has failed until the voltage Va1 becomes equal to or greater than the threshold and the voltage Va1 becomes equal to or greater than the voltage Va2. Furthermore, the control unit 13 determines that regenerative power is being generated from the load 3 when, for example, the voltage Va2 is greater than the voltage Va1.

[0027] When the power source 2 is not failing, the control unit 13 controls the power conversion unit 12 so that the charging voltage supplied from the power conversion unit 12 to the power storage unit 11 is equal to or less than the threshold value Vth. The control unit 13 sets a set value Vb1 stored in advance in the control unit 13 as the threshold value Vth. The set value Vb1 corresponds to the first threshold value in the present disclosure. In other words, when the power source 2 is not failing, the control unit 13 causes the power conversion unit 12 to perform charging control so that the charging voltage supplied from the power conversion unit 12 to the power storage unit 11 is equal to or less than the set value Vb1.

[0028] In addition, when the power source 2 fails and the load 3 is not generating regenerative power, the control unit 13 controls the power conversion unit 12 to supply power from the storage unit 11 to the load 3 via the power conversion unit 12.

[0029] Furthermore, when the power source 2 fails and the load 3 is generating regenerative power, the control unit 13 controls the power conversion unit 12 so that the charging voltage supplied from the power conversion unit 12 to the power storage unit 11 is equal to or lower than the threshold value Vth. Here, the control unit 13 sets a set value Vb2 previously stored in the control unit 13 as the threshold value Vth. The set value Vb2 is greater than the set value Vb1. That is, when the power source 2 fails, the control unit 13 changes the threshold value Vth from the set value Vb1 to the set value Vb2. The set value Vb2 corresponds to the second threshold value in the present disclosure. This allows the power storage unit 11 to be charged with the regenerative power, for example, even when the charging voltage supplied from the power conversion unit 12 to the power storage unit 11 exceeds the set value Vb1 when regenerative power is generated from the load 3.

[0030] (2) Operation FIG. 3 is a flowchart showing the operation of the control unit 13 in the power supply system 1 according to the first embodiment.

[0031] The control unit 13 determines whether the power supply 2 has failed (step S1). The control unit 13 determines whether the power supply 2 has failed, for example, based on the value of the voltage Va1 at the first terminal Ta1 and the value of the voltage Va2 at the second terminal Ta2. If the power supply 2 has not failed (No in step S1), the control unit 13 sets the threshold Vth of the power conversion unit 12 to a set value Vb1 (step S2). More specifically, if the threshold Vth of the power conversion unit 12 is the set value Vb1, the control unit 13 does nothing. If the threshold Vth of the power conversion unit 12 is the set value Vb2, the control unit 13 changes the threshold Vth of the power conversion unit 12 from the set value Vb2 to the set value Vb1. The control unit 13 then controls the charging of the power conversion unit 12 so that the charging voltage Va4 supplied from the power conversion unit 12 to the power storage unit 11 is equal to or lower than the threshold Vth (step S6). As a result, when the power supply 2 is not faulty, the power supply system 1 is controlled so that power is stored in the power storage unit 11. Furthermore, by preventing the power storage unit 11 from being overcharged, it is possible to reduce deterioration of the power storage unit 11.

[0032] On the other hand, if the power supply 2 has failed (Yes in step S1), the control unit 13 sets the threshold Vth of the power conversion unit 12 to the set value Vb2 (step S5). More specifically, if the threshold Vth of the power conversion unit 12 is the set value Vb1, the control unit 13 changes the threshold Vth of the power conversion unit 12 from the set value Vb1 to the set value Vb2. Note that if the threshold Vth of the power conversion unit 12 is the set value Vb2, the control unit 13 does nothing.

[0033] After step S5, the control unit 13 determines whether regenerative power is being generated in the load 3 (step S3). For example, if the voltage Va2 at the second terminal Ta2 is higher than the voltage Va1 at the first terminal Ta1, the control unit 13 determines that regenerative power is being generated in the load 3. If regenerative power is not being generated in the load 3 (No in step S3), the control unit 13 controls the discharge of the power conversion unit 12 so that the power of the power storage unit 11 is supplied to the load 3 via the power conversion unit 12 (step S4). As a result, if the power supply 2 fails and regenerative power is not being generated from the load 3, the power supply system 1 is controlled so that power is supplied from the power storage unit 11 to the load 3.

[0034] On the other hand, if regenerative power is being generated in the load 3 (Yes in step S3), the control unit 13 controls the charging of the power conversion unit 12 so that the charging voltage Va4 supplied from the power conversion unit 12 to the power storage unit 11 is equal to or lower than the threshold Vth (step S6). As a result, when the power supply 2 fails, the regenerative power is used to charge the power storage unit 11, thereby making it possible to effectively utilize power. Furthermore, when the power supply 2 fails, the threshold Vth is changed to the set value Vb2, which is larger than the set value Vb1, so that the regenerative power generated in the load 3 is more likely to be charged to the power storage unit 11, thereby delaying the complete discharge of the power storage unit 11.

[0035] (3) Effects The power supply system 1 according to the first embodiment includes a first terminal Ta1, a second terminal Ta2, and a backup power supply unit 10. The first terminal Ta1 is connected to the power supply 2. The second terminal Ta2 is connected to the load 3. The backup power supply unit 10 is connected to a power supply path R1. The power supply path R1 connects the first terminal Ta1 and the second terminal Ta2. The backup power supply unit 10 includes a power storage unit 11 and a power conversion unit 12. The power conversion unit 12 is connected between the power storage unit 11 and the power supply path R1. In a state in which the power supply 2 fails, the power conversion unit 12 supplies regenerative power generated in the load 3 to the power storage unit 11 via the power conversion unit 12. This makes it possible for the power supply system 1 according to the first embodiment to effectively utilize regenerative power even in a state in which the power supply fails.

[0036] Furthermore, the power supply system 1 according to the first embodiment includes a control unit 13 that controls the power conversion unit 12 so that the charging voltage Va4 supplied from the power conversion unit 12 to the power storage unit 11 is equal to or lower than a threshold value. A set value Vb2 that is a threshold value when the power supply 2 has failed is higher than a set value Vb1 that is a threshold value when the power supply 2 is not failing. As a result, in the power supply system according to the first embodiment, when the power supply 2 has failed, regenerative power generated by the load 3 is more likely to be charged into the power storage unit 11, and complete discharge of the power storage unit 11 can be delayed.

[0037] Furthermore, in the power supply system 1 according to the first embodiment, the control unit 13 stores the set value Vb1 and the set value Vb2 in advance. When the power supply 2 fails, the control unit 13 changes the threshold value from the set value Vb1 to the set value Vb2. This allows the power supply system according to the first embodiment to easily change the operation of the power conversion unit 12 by the control unit 13 when the power supply 2 fails.

[0038] Furthermore, in the control method for the power supply system 1 according to the first embodiment, the power supply system 1 includes a first terminal Ta1, a second terminal Ta2, and a backup power supply unit 10. The first terminal Ta1 is connected to the power supply 2. The second terminal Ta2 is connected to the load 3. The backup power supply unit 10 is connected to a power supply path R1. The power supply path R1 connects the first terminal Ta1 and the second terminal Ta2. The backup power supply unit 10 includes a power storage unit 11 and a power conversion unit 12. The power conversion unit 12 is connected between the power storage unit 11 and the power supply path R1. In the control method for the power supply system 1 according to the first embodiment, in a state in which the power supply 2 fails, the power conversion unit 12 is controlled so that regenerative power generated in the load 3 is supplied to the power storage unit via the power conversion unit 12. As a result, the control method for the power supply system 1 according to the first embodiment makes it possible to effectively utilize regenerative power even in a state in which the power supply fails.

[0039] (Modification) (1) Configuration In power supply system 1 according to a modification of embodiment 1, control unit 13 holds set value Vb1, which is threshold value Vth when power supply 2 is not failing. Control unit 13 also sets set value Vb2 based on set value Vb1, internal resistance Re1 of power storage unit 11, and charging current I1 generated in load 3.

[0040] When power supply 2 fails and regenerative power is being generated in load 3, the regenerative power generated in load 3 flows from second terminal Ta2 through third terminal Ta3 to backup power supply unit 10, as shown in Fig. 4. Control unit 13 sets set value Vb2 based on set value Vb1, internal resistance Re1 of power storage unit 11, and charging current I1 generated in load 3. Specifically, control unit 13 sets set value Vb2 to be greater than set value Vb1 by an integrated value Re1·I1 of charging current I1 generated in load 3 and internal resistance Re1 of power storage unit 11. That is, set values ​​Vb1 and Vb2 satisfy the following equation:

[0041] Vb2 = Vb1 + Re1 · I1 The control unit 13 measures, for example, the amount of current flowing between the first terminal Ta1 and the third terminal Ta3 and the amount of current flowing between the second terminal Ta2 and the third terminal Ta3. For example, when the power source 2 is not in a fault state and the power storage unit 11 is being charged from the power source 2, the control unit 13 measures the internal resistance Re1 of the power storage unit 11 from the relationship between the amount of current flowing between the first terminal Ta1 and the third terminal Ta3 and the electromotive force Va4 of the power storage unit 11. When the power source 2 is in a fault state and regenerative power is being generated in the load 3, the control unit 13 changes the threshold value Vth of the power conversion unit 12 to, for example, a set value Vb2 calculated based on the amount of current flowing between the first terminal Ta1 and the third terminal Ta3 and the internal resistance Re1 of the power storage unit 11.

[0042] In power supply system 1 according to the modification of embodiment 1, when power supply 2 is in a failure state and regenerative power is being generated in load 3, threshold value Vth of power conversion unit 12 can be set taking into consideration the voltage drop due to internal resistance Re1 of power storage unit 11. Therefore, power supply system 1 according to the modification of embodiment 1 can prevent an overvoltage from being applied to power storage unit 11 while allowing charging of power storage unit 11 using regenerative power from load 3.

[0043] (2) Effects In power supply system 1 according to the modification of embodiment 1, control unit 13 stores set value Vb1 in advance. Control unit 13 sets set value Vb2 based on set value Vb1, internal resistance Re1 of power storage unit 11, and charging current I1 generated in load 3 when power supply 2 fails. As a result, power supply system 1 according to the modification of embodiment 1 allows charging of power storage unit 11 using regenerative power from load 3, while preventing an overvoltage from being applied to power storage unit 11.

[0044] Second Embodiment (1) Configuration As shown in FIG. 5, a power supply system 1a according to the second embodiment further includes a first switch SW1 and a second switch SW2.

[0045] In the power supply system 1a according to the second embodiment, a power supply path R1 connecting a first terminal Ta1 and a second terminal Ta2 includes a first electrical circuit R11 and a second electrical circuit R12 connected in parallel to each other. A first switch SW1 is disposed in the first electrical circuit R11. A second switch SW2 and a diode D1 are disposed in the second electrical circuit R12. A backup power supply unit 10 is connected to the second electrical circuit R12.

[0046] The first electrical path R11 connects the first terminal Ta1 and the second terminal Ta2. The first switch SW1 is disposed on the first electrical path R11. More specifically, a first end of the first switch SW1 is connected to the first terminal Ta1. A second end of the first switch SW1 is connected to the second terminal Ta2. Therefore, when the first switch SW1 is in the on state, the first terminal Ta1 and the second terminal Ta2 are electrically connected. Note that the backup power supply unit 10 is not connected to the first electrical path R11. Therefore, the backup power supply unit 10 does not charge or discharge via the first electrical path R11.

[0047] The second electrical path R12 connects the first terminal Ta1, the second terminal Ta2, and the backup power supply unit 10. The second switch SW2 is disposed on the second electrical path R12 between the second terminal Ta2 and the backup power supply unit 10. More specifically, a first end of the second switch SW2 is connected to the third terminal Ta3. A second end of the second switch SW2 is connected to the second terminal Ta2. When the second switch SW2 is in the on state, the second terminal Ta2 and the third terminal Ta3 are electrically connected. Therefore, the backup power supply unit 10 supplies power to the load 3 via the second switch SW2, and also receives power from regenerated power generated in the load 3.

[0048] In the second electrical path R12, the diode D1 is connected between the first terminal Ta1 and the third terminal Ta3 so that the forward direction is from the first terminal Ta1 to the third terminal Ta3. Therefore, when the power source 2 is not faulty, charging from the power source 2 to the backup power supply unit 10 occurs via the second electrical path R12. On the other hand, regenerative power generated in the load 3 and power discharged from the backup power supply unit 10 are blocked by the diode D1 and do not flow into the power source 2.

[0049] The control unit 13 controls the operation of the power conversion unit 12 and the first switch SW1 and the second switch SW2 based on whether the power supply 2 has failed and whether regenerative power is being generated from the load 3.

[0050] When the power supply 2 has not failed, the control unit 13 turns on at least one of the first switch SW1 and the second switch SW2. More specifically, when the power supply 2 has not failed, the control unit 13 turns on the first switch SW1 and turns off the second switch SW2, as shown in Fig. 6. This causes power to be supplied from the power supply 2 to the load 3 via the first electrical path R11, and also causes power to be supplied from the power supply 2 to the backup power supply unit 10 via the second electrical path R12.

[0051] Furthermore, when the power supply 2 fails, the control unit 13 turns the first switch SW1 off and the second switch SW2 on, as shown in FIG. 7 . This connects the load 3 and the backup power supply unit 10 via the second electrical path R12. Therefore, power is supplied from the backup power supply unit 10 to the load 3, and regenerative power generated in the load 3 is used to charge the backup power supply unit 10. Meanwhile, the failed power supply 2 is isolated from the backup power supply unit 10 and the load 3 by the diode D1. Therefore, power discharged from the backup power supply unit 10 and regenerative power from the load 3 are not supplied to the power supply 2, making it easier to use the regenerative power from the load 3 to charge the backup power supply unit 10, and also reducing deterioration of the condition of the power supply 2 due to the application of a voltage to the power supply 2.

[0052] Therefore, in the power supply system 1a according to the second embodiment, it is possible to perform more suitable control when the power supply 2 fails.

[0053] (2) Effects The power supply system 1a according to the second embodiment further includes a first switch SW1 and a second switch SW2. The power supply path R1 includes a first electrical circuit R11 and a second electrical circuit R12. The first electrical circuit R11 connects the first terminal Ta1 and the second terminal Ta2. The second electrical circuit R12 is connected in parallel with the first electrical circuit R11 and connects the first terminal Ta1, the second terminal Ta2, and the backup power supply unit 10. The first switch SW1 is disposed on the first electrical circuit R11. The second switch SW2 is disposed on the second electrical circuit R12 between the third terminal Ta3 and the backup power supply unit 10. When the power supply 2 fails, the first switch SW1 is turned off and the second switch SW2 is turned on. When the power supply 2 is not failed, at least one of the first switch SW1 and the second switch SW2 is turned on. As a result, in the power supply system 1a according to the second embodiment, it is possible to perform more appropriate control when the power supply 2 fails.

[0054] (Embodiment 3) (1) Configuration The power supply system 1 according to embodiment 3 has the same configuration as the power supply system 1 according to embodiment 1. The power conversion unit 12 controls charging and discharging of the power storage unit 11 based on the current. The control unit 13 controls the operation of the power conversion unit 12 based on whether the power supply 2 has failed and whether regenerative power is being generated from the load 3.

[0055] The control unit 13 controls the power conversion unit 12. More specifically, when the power supply 2 has not failed, the control unit 13 controls the charging of the power conversion unit 12. At this time, the control unit 13 controls the power conversion unit 12 so that the charging current supplied from the power conversion unit 12 to the power storage unit 11 is equal to or less than a threshold. For example, when the power supply 2 has not failed, the control unit 13 sets the threshold to a first set value that is stored in advance in the control unit 13.

[0056] Furthermore, when the power supply fails and no regenerative power is generated from the load 3, the control unit 13 controls the power conversion unit 12 to discharge.

[0057] Furthermore, when the power supply 2 fails and regenerative power is being generated from the load 3, the control unit 13 controls the charging of the power conversion unit 12. At this time, the control unit 13 controls the power conversion unit 12 so that the charging current supplied from the power conversion unit 12 to the power storage unit 11 is equal to or less than a threshold. For example, when the power supply 2 does not fail, the control unit 13 sets the threshold to a second set value previously stored in the control unit 13. Here, the second set value is greater than the first set value. The first set value corresponds to the first threshold in the present disclosure. The second set value corresponds to the second threshold in the present disclosure.

[0058] In the power supply system 1 according to the third embodiment, when the power supply 2 fails, it is also possible to effectively utilize power by using regenerative power to charge the power storage unit 11. Furthermore, when the power supply 2 fails, the threshold value is increased, which makes it easier for the regenerative power from the load 3 to be charged to the power storage unit 11.

[0059] (2) Effects The power supply system 1 according to the third embodiment includes a control unit 13. The control unit 13 controls the power conversion unit 12 so that the charging current supplied from the power conversion unit 12 to the power storage unit 11 is equal to or less than a threshold. The second set value, which is the threshold when the power supply 2 has failed, is greater than the first set value, which is the threshold when the power supply 2 has not failed. As a result, in the power supply system 1 according to the third embodiment, by raising the threshold when the power supply 2 has failed, it becomes easier for the regenerative power from the load 3 to be charged to the power storage unit 11.

[0060] Furthermore, in the power supply system 1 according to the third embodiment, the control unit 13 stores a first set value and a second set value in advance. When the power supply 2 fails, the control unit 13 changes the threshold value from the first set value to the second set value. This allows the power supply system 1 according to the third embodiment to easily change the operation of the power conversion unit 12 when the power supply 2 fails.

[0061] (Modification) (1) Configuration In the power supply system 1 according to the modification of the third embodiment, the control unit 13 holds a first set value that is a threshold value when the power supply 2 is not failing. The control unit 13 also sets a second set value based on the charging current I1 generated in the load 3.

[0062] When the power supply 2 fails and the load 3 is generating regenerative power, the regenerative power generated in the load 3 flows into the backup power supply unit 10 via the second terminal Ta2 and the third terminal Ta3, as shown in Fig. 4. The control unit 13 sets a threshold value based on the charging current I1 generated in the load 3. For example, the control unit 13 sets the value of the charging current I1 as the current threshold value of the power conversion unit 12.

[0063] In the power supply system 1 according to the modified example of the first embodiment, when the power supply 2 is in a faulty state and regenerative power is being generated in the load 3, the threshold value is set based on the charging current I1 generated in the load 3, which makes it easy to change the threshold value.

[0064] (2) Effects In power supply system 1 according to the modification of embodiment 3, control unit 13 sets the second set value based on charging current I1 generated in load 3 when power supply 2 fails. This makes it easier to charge power storage unit 11 using regenerative power generated in load 3, while preventing the current flowing through power storage unit 11 from becoming an overcurrent.

[0065] (Other Modifications of the Embodiments) (1) In the first to third embodiments and their modifications, the power storage unit 11 includes the electric double layer capacitor C1, but the power storage unit 11 may include any device that can be charged and discharged. For example, the power storage unit 11 may include a secondary battery, such as a lithium-ion battery.

[0066] (2) In the first to third embodiments and their modified examples, the positive electrode of the power supply 2 and the positive electrode of the load 3 are connected to the power supply system 1, and the negative electrode of the power supply 2 and the negative electrode of the load 3 are connected to ground. However, for example, the negative electrode of the power supply 2 and the negative electrode of the load 3 may be connected to the power supply system 1. In this case, for example, the negative electrode of the power supply 2, the negative electrode of the load 3, and the negative electrode of the power storage unit 11 are connected to one another.

[0067] Alternatively, for example, the negative electrode of the power supply 2 and the negative electrode of the load 3 may be connected to the power supply system 1, and the positive electrode of the power supply 2 and the positive electrode of the load 3 may be connected to ground. In this case, in the backup power supply unit 10, the negative electrode of the power storage unit 11 is connected to the power conversion unit 12, and the positive electrode of the power storage unit 11 is connected to ground.

[0068] (3) In embodiments 1 to 3 and their variations, the control unit 13 is included in the backup power supply unit 10, but the control unit 13 may be included in the power supply system 1 and may not be a component of the backup power supply unit 10.

[0069] (Aspect) A power supply system (1; 1a) according to a first aspect includes a power supply terminal (Ta1), a load terminal (Ta2), and a backup power supply unit (10). The power supply terminal (Ta1) is connected to a power supply (2). The load terminal (Ta2) is connected to a load (3). The backup power supply unit (10) is connected to a power supply path (R1). The power supply path (R1) connects between the power supply terminal (Ta1) and the load terminal (Ta2). The backup power supply unit (10) includes a power storage unit (11) and a power conversion unit (12). The power conversion unit (12) is connected between the power storage unit (11) and the power supply path (R1). When the power supply (2) fails, the power conversion unit (12) supplies regenerative power generated in the load (3) to the power storage unit (11) via the power conversion unit (12).

[0070] According to the power supply system (1; 1a) of the above aspect, it is possible to effectively utilize regenerative power even in a state where the power supply (2) has failed.

[0071] The power supply system (1a) according to the second aspect is the same as the first aspect, but further includes a first switch (SW1) and a second switch (SW2). The power supply path (R1) includes a first electrical path (R11) and a second electrical path (R12). The first electrical path (R11) connects the power supply terminal (Ta1) and the load terminal (Ta2). The second electrical path (R12) is connected in parallel with the first electrical path (R11) and connects the power supply terminal (Ta1), the load terminal (Ta2), and the backup power supply unit (10). The first switch (SW1) is arranged in the first electrical path (R11). The second switch (SW2) is arranged in the second electrical path (R12) between the load terminal (Ta2) and the backup power supply unit (10). When the power supply (2) fails, the first switch (SW1) is turned off and the second switch (SW2) is turned on. When the power supply (2) does not fail, at least one of the first switch (SW1) and the second switch (SW2) is turned on.

[0072] According to the power supply system (1a) of the above aspect, it is possible to perform more suitable control when the power supply (2) fails.

[0073] The power supply system (1; 1a) according to a third aspect is the first or second aspect, further comprising a control unit (13). The control unit (13) controls the power conversion unit (12) so that a charging voltage (Va4) supplied from the power conversion unit (12) to the power storage unit (11) is equal to or lower than a threshold. A second threshold (Vb2), which is a threshold when the power supply (2) has failed, is higher than a first threshold (Vb1), which is a threshold when the power supply is not failed.

[0074] According to the power supply system (1; 1a) of the above aspect, when the power supply (2) fails, the regenerative power from the load (3) is likely to be charged into the power storage unit (11).

[0075] In the power supply system (1; 1a) according to the fourth aspect, in the third aspect, the control unit (13) stores a first threshold value (Vb1) and a second threshold value (Vb2) in advance, and when the power supply (2) fails, the control unit (13) changes the threshold value from the first threshold value (Vb1) to the second threshold value (Vb2).

[0076] According to the power supply system (1; 1a) of the above aspect, when the power supply (2) fails, the control unit (13) can easily change the operation of the power conversion unit (12).

[0077] In the power supply system (1; 1a) according to the fifth aspect, in the third aspect, the control unit (13) stores a first threshold value (Vb1) in advance. The control unit (13) sets a second threshold value (Vb2) based on the first threshold value (Vb1), the internal resistance of the power storage unit (11), and a charging current (I1) generated in the load (3) when the power source (2) fails.

[0078] According to the power supply system (1; 1a) of the above aspect, it is possible to charge the power storage unit (11) with a charging current from the load (3) while preventing an overvoltage from being applied to the power storage unit (11).

[0079] The power supply system (1; 1a) according to a sixth aspect is the first or second aspect, further comprising a control unit (13). The control unit (13) controls the power conversion unit (12) so that a charging current (I1) supplied from the power conversion unit (12) to the power storage unit (11) is equal to or less than a threshold. A second threshold, which is a threshold when the power supply (2) has failed, is greater than a first threshold, which is a threshold when the power supply (2) has not failed.

[0080] According to the power supply system (1; 1a) of the above aspect, when the power supply (2) fails, the regenerative power from the load (3) is likely to be charged into the power storage unit (11).

[0081] In the power supply system (1; 1a) according to the seventh aspect, in the sixth aspect, the control unit (13) stores a first threshold value and a second threshold value in advance, and when the power supply (2) fails, the control unit (13) changes the threshold value from the first threshold value to the second threshold value.

[0082] According to the power supply system (1; 1a) of the above aspect, when the power supply (2) fails, the control unit (13) can easily change the operation of the power conversion unit (12).

[0083] In the power supply system (1; 1a) according to the eighth aspect, the control unit (13) sets the second threshold value based on the charging current (I1) generated in the load (3) when the power supply (2) fails.

[0084] According to the power supply system (1; 1a) of the above aspect, it is possible to charge the power storage unit (11) with a charging current from the load (3) while preventing an overcurrent from flowing to the power storage unit (11).

[0085] In a control method for a power supply system (1; 1a) according to a ninth aspect, the power supply system (1; 1a) includes a power supply terminal (Ta1), a load terminal (Ta2), and a backup power supply unit (10). The power supply terminal (Ta1) is connected to a power supply (2). The load terminal (Ta2) is connected to a load (3). The backup power supply unit (10) is connected to a power supply path (R1). The power supply path (R1) connects between the power supply terminal (Ta1) and the load terminal (Ta2). The backup power supply unit (10) includes a power storage unit (11) and a power conversion unit (12). The power conversion unit (12) is connected between the power storage unit (11) and the power supply path (R1). In the control method for the power supply system (1; 1a), when the power supply (2) fails, the power conversion unit (12) is controlled so that regenerative power generated in the load (3) is supplied to the power storage unit (11) via the power conversion unit (12).

[0086] The control method for the power supply system (1; 1a) according to the above aspect makes it possible to effectively utilize regenerative power even in a state where the power supply (2) has failed.

[0087] REFERENCE SIGNS LIST 1, 1a Power supply system 10 Backup power supply unit 11 Power storage unit 12 Power conversion unit 13 Control unit 2 Power supply 3 Load Ta1 First terminal (power supply terminal) Ta2 Second terminal (load terminal) R1 Power supply path R11 First current path R12 Second current path SW1 First switch SW2 Second switch Va4 Voltage (charging voltage) Vb1 Set value (first threshold) Vb2 Set value (second threshold) I1 Charging current

Claims

1. A power supply system comprising: a power supply terminal connected to a power supply; a load terminal connected to a load; and a backup power supply unit connected to a power supply path connecting the power supply terminal and the load terminal, wherein the backup power supply unit includes a power storage unit and a power conversion unit connected between the power storage unit and the power supply path, and wherein the power conversion unit supplies regenerative power generated in the load to the power storage unit via the power conversion unit when the power supply fails.

2. The power supply system according to claim 1, further comprising a first switch and a second switch, wherein the power supply path includes: a first electric circuit connecting the power supply terminal and the load terminal; and a second electric circuit connected in parallel to the first electric circuit and connecting the power supply terminal, the load terminal, and the backup power supply unit, wherein the first switch is disposed on the first electric circuit, and the second switch is disposed on the second electric circuit between the load terminal and the backup power supply unit, and wherein, when the power supply fails, the first switch is turned off and the second switch is turned on, and when the power supply does not fail, at least one of the first switch and the second switch is turned on.

3. The power supply system according to claim 1 or 2, further comprising a control unit that controls the power conversion unit so that the charging voltage supplied from the power conversion unit to the storage unit is equal to or lower than a threshold, wherein a second threshold that is the threshold when the power supply has failed is higher than a first threshold that is the threshold when the power supply is not failing.

4. The power supply system according to claim 3, wherein the control unit stores the first threshold value and the second threshold value in advance, and changes the threshold value from the first threshold value to the second threshold value when the power supply fails.

5. The power supply system according to claim 3, wherein the control unit stores the first threshold value in advance, and sets the second threshold value based on the first threshold value, the internal resistance of the storage unit, and a charging current generated in the load when the power supply fails.

6. The power supply system according to claim 1 or 2, further comprising a control unit that controls the power conversion unit so that the charging current supplied from the power conversion unit to the storage unit is equal to or less than a threshold, wherein a first threshold that is the threshold when the power supply is not failing is greater than a second threshold that is the threshold when the power supply is not failing.

7. The power supply system according to claim 6, wherein the control unit stores the first threshold value and the second threshold value in advance, and changes the threshold value from the first threshold value to the second threshold value when the power supply fails.

8. The power supply system according to claim 6, wherein the control unit sets the second threshold value based on a charging current generated in the load when the power supply fails.

9. A control method for a power supply system, wherein the power supply system comprises: a power supply terminal connected to a power supply; a load terminal connected to a load; and a backup power supply unit connected to a power supply path connecting the power supply terminal and the load terminal, the backup power supply unit including a power storage unit and a power conversion unit connected between the power storage unit and the power supply path, the control method for a power supply system comprising: controlling the power conversion unit so that regenerative power generated in the load is supplied to the power storage unit via the power conversion unit when the power supply fails.

Images