In-vehicle backup power supply device

Abstract

Provided is a technology that enables a backup operation in case of failure even without using a dedicated backup power source. The in-vehicle backup power supply device (1) includes a battery unit (10) formed by connecting a plurality of unit batteries (10A) in series, a discharge circuit (11) that performs a first discharge operation of supplying power to a third conduction path (31A) based on the charge stored in the battery unit (10), an equalization circuit (70) that performs a cell equalization operation of the battery unit (10), and a control unit (12) that controls the equalization circuit (70). The equalization circuit (70) is configured to perform a second discharge operation of supplying power to the third conduction path (31A) based on the charge stored in a plurality of power storage elements (71A). The control unit (12) performs a first control for causing the equalization circuit (70) to perform a cell equalization operation and a second control for causing the equalization circuit (70) to perform a second discharge operation, and performs the second control in the case of a failure in which the first discharge operation is not normally performed.

Description

Technical Field

[0001] The present disclosure relates to an in-vehicle backup power supply device. Background Art

[0002] When a failure state such as a power supply cut-off from the main power supply occurs in an in-vehicle power supply system, power is no longer supplied to the load, and the electrical operation of the load cannot be performed. However, depending on the load, there are also cases where continued operation is strongly required. Therefore, as a structure that responds to such a demand, a structure in which a dedicated backup power supply different from the main power supply is additionally provided is known. Patent Documents 1 and 2 disclose an example of such a power supply system.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-13136

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2018-62253

[0007] Patent Document 3: International Publication No. 2015 / 105923 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, if a dedicated backup power supply is provided only for performing backup operation in case of failure, the size and weight of the device will increase accordingly.

[0010] Therefore, in the present disclosure, a technique is proposed that enables backup operation in case of failure without using a dedicated backup power supply.

[0011] Solution to the Problem

[0012] The in-vehicle backup power supply device of the present disclosure is an in-vehicle backup power supply device in an in-vehicle power supply system. The in-vehicle backup power supply device includes a battery unit formed by connecting a plurality of unit batteries in series and a discharge circuit that performs a first discharge operation of supplying power to a conductive path on the load side based on the charge stored in the battery unit. The in-vehicle backup power supply device includes: a balancing circuit that performs a cell balancing operation on the battery unit; and a control unit that controls the balancing circuit. The balancing circuit is configured to perform a second discharge operation of supplying power to the conductive path on the load side based on the charge stored in a plurality of power storage elements. The control unit performs a first control for causing the balancing circuit to perform the cell balancing operation and a second control for causing the balancing circuit to perform the second discharge operation, and performs the second control in the case of a failure in which the first discharge operation is not normally performed.

[0013] Advantages of the Invention

[0014] According to the present disclosure, a standby operation can be performed with a simple structure without providing a dedicated structure for backing up the battery unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 1, and the switching element is in a non-connected state.

[0016] Figure 2 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 1, and the switching element is in a state of performing a first operation.

[0017] Figure 3 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 1, and the switching element is in a state of performing a second operation.

[0018] Figure 4 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 1, and the equalization circuit is in a state of performing a second discharge operation.

[0019] Figure 5 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 1, and is a state in which the end element electrode portion is electrically connected to the end electrode portion of a unit cell that cannot normally discharge, and the inter-element electrode portion adjacent to the end element electrode portion is electrically connected to the inter-battery electrode portion adjacent to the end electrode portion.

[0020] Figure 6 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 2, and the switching element is in a non-connected state.

[0021] Figure 7 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 3, and the first switching element and the second switching element are in a non-connected state.

[0022] Figure 8 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 3, and is in a state of performing a first discharge operation.

[0023] Figure 9 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 3, and the switching unit is in a state of performing an alternative operation.

[0024] Figure 10 is a circuit diagram schematically showing an in-vehicle standby power supply device according to Embodiment 4, and the first switching element and the second switching element are in a non-connected state.

[0025] Figure 11 is a circuit diagram schematically showing an in-vehicle backup power supply device according to Embodiment 4, and the switching unit is in a state of performing an alternative operation.

[0026] Figure 12 is a circuit diagram schematically showing an in-vehicle backup power supply device according to Embodiment 5, and the first switching element, the second switching element, and the power storage unit switching unit are in a non-connected state.

[0027] Figure 13 is a circuit diagram schematically showing an in-vehicle backup power supply device according to Embodiment 5, and the power storage unit switching unit is in a state of performing a third operation.

[0028] Figure 14 is a circuit diagram schematically showing an in-vehicle backup power supply device according to Embodiment 5, and the power storage unit switching unit is in a state of performing a fourth operation. Detailed Embodiments

[0029] [Description of Embodiments of the Present Disclosure]

[0030] First, embodiments of the present disclosure will be listed and described.

[0031] (1) The in-vehicle backup power supply device of the present disclosure is an in-vehicle backup power supply device in an in-vehicle power supply system including a battery unit formed by connecting a plurality of unit batteries in series and a discharge circuit that performs a first discharge operation of supplying power to a conductive path on the load side based on the charge stored in the battery unit. The in-vehicle backup power supply device of the present disclosure includes a balancing circuit that performs a cell balancing operation on the battery unit and a control unit that controls the balancing circuit. The balancing circuit is configured to perform a second discharge operation of supplying power to a conductive path on the load side based on the charge stored in a plurality of power storage elements. The control unit performs a first control for causing the balancing circuit to perform a cell balancing operation and a second control for causing the balancing circuit to perform a second discharge operation, and performs the second control when a failure in which the first discharge operation is not normally performed occurs. Thus, the in-vehicle backup power supply device of the present disclosure can perform a backup operation with a simple structure without providing a dedicated structure for backing up the battery unit.

[0032] (2) The in-vehicle backup power supply device of the present disclosure has a plurality of balancing circuits, the battery unit has a plurality of unit battery groups, and each of the plurality of balancing circuits corresponds to each of the plurality of unit battery groups. The control unit can operate each of the balancing circuits independently.

[0033] If configured in this way, even if one balancing circuit becomes inoperable, the operation of other balancing circuits can be continued, so that the backup operation can be performed more reliably.

[0034] (3) The discharge circuit of the in-vehicle backup power supply device of the present disclosure has a converter that boosts or steps down the input voltage and outputs it. The control unit can operate the converter in the case of performing the second control to boost or step down the input voltage based on the power supplied from the energy storage element and apply power to the conductive circuit on the load side.

[0035] If configured in this way, it is possible to supply power of a desired magnitude to the conductive circuit on the load side based on the power from the energy storage element. In particular, when boosting the power from the energy storage element by the converter, the power stored in the energy storage element can be effectively used.

[0036] (4) The discharge circuit of the in-vehicle backup power supply device of the present disclosure has a converter that boosts or steps down the input voltage and outputs it. The control unit can operate the converter in the case of performing the first control to boost or step down the input voltage based on the power supplied from the energy storage element and supply power to the battery unit side.

[0037] If configured in this way, when the equalization circuit performs the cell equalization operation, by boosting the power from the energy storage unit using the converter, it is possible to suppress a decrease in the current flowing between the energy storage unit and the battery unit when the cell equalization operation progresses to a certain extent. Thereby, it is possible to actively make the current flow from the energy storage unit toward the battery unit, and the time required for the equalization operation can be made shorter.

[0038] (5) The discharge circuit of the in-vehicle backup power supply device of the present disclosure has a converter that boosts or steps down the input voltage and outputs it. The control unit operates the converter in the case of performing the first control to boost or step down the input voltage based on the power supplied from the energy storage element and supply power to the battery unit. Moreover, the control unit can operate the converter in the case of performing the second control to boost or step down the input voltage based on the power supplied from the energy storage element and supply power to the conductive circuit on the load side.

[0039] If configured in this way, in the case where the equalization circuit performs the second discharge operation, it is possible to supply power of a desired magnitude to the conductive circuit on the load side based on the power from the energy storage unit. In particular, when boosting the input voltage based on the power from the energy storage unit by the converter, the power stored in the energy storage unit can be effectively used. Moreover, when performing the cell equalization operation, by boosting the input voltage based on the power from the energy storage unit using the converter, a decrease in the current flowing between the energy storage unit and the unit cell when the cell equalization operation progresses to a certain extent is suppressed. And it is possible to actively exchange current between the energy storage unit and the unit cell. Thereby, the time required for the equalization operation can be made shorter.

[0040] (6) In the in-vehicle backup power supply device of the present disclosure, the battery unit has an end electrode portion and an inter-battery electrode portion between unit cells. The equalization circuit has a power storage portion formed by connecting a plurality of power storage elements in series and a switching portion having a plurality of switching elements. The power storage portion has an end element electrode portion and an inter-element electrode portion between the power storage elements. Each switching element corresponds to each unit cell. The inter-element electrode portion or the end element electrode portion corresponding to each unit cell is electrically connected to the electrode on the high potential side or the low potential side of the unit cell corresponding to the switching element. When performing the first control, the control portion operates each switching element corresponding to each unit cell so that the inter-element electrode portion or the end element electrode portion corresponding to the unit cell is alternately electrically connected to the electrode on the high potential side and the electrode on the low potential side of the unit cell. When performing the second control, the control portion can operate the switching element so that the inter-element electrode portion or the end element electrode portion is electrically connected to at least two electrode portions of the inter-battery electrode portion or the end electrode portion one by one.

[0041] If configured in this way, since it is a structure in which the inter-element electrode portion or the end element electrode portion is electrically connected to at least two electrode portions of the inter-battery electrode portion or the end electrode portion one by one, not only can the battery unit be backed up, but also each unit cell can be backed up.

[0042] (7) In the in-vehicle backup power supply device of the present disclosure, the equalization circuit has a power storage portion formed by one or more power storage elements and a switching portion having a plurality of switching elements. Each switching element corresponds to each unit cell. The end element electrode portion at one end of the power storage portion is electrically connected to the electrode on the high potential side of the unit cell corresponding to the switching element, and the end element electrode portion at the other end of the power storage portion is electrically connected to the electrode on the low potential side of the unit cell corresponding to the switching element. When performing the first control, the control portion electrically connects the end element electrode portion at one end of the power storage portion to the electrode on the high potential side of one unit cell. At the same time, the control portion operates the plurality of switching elements so that the electrodes on the low potential sides of the plurality of unit cells are alternately electrically connected to the end element electrode portion at the other end of the power storage portion. When performing the second control, the control portion can operate the plurality of switching elements so that the electrodes on the high potential side and the low potential side of the unit cell are not connected to the end element electrode portion.

[0043] If configured in this way, a single power storage element can be used to perform the cell equalization operation, so that the power supply device itself can be miniaturized.

[0044] (8) In the in-vehicle backup power supply device of the present disclosure, the equalization circuit includes a power storage unit composed of one or more power storage elements and a switching unit having a plurality of switching elements. Each switching element corresponds to each unit cell. The electrode on the high-potential side of the unit cell corresponding to the switching element is electrically connected to one end element electrode portion of the power storage unit via a converter, and the electrode on the low-potential side of the unit cell corresponding to the switching element is electrically connected to the other end element electrode portion of the power storage unit via a converter. When performing the first control, the control unit electrically connects the electrode on the high-potential side of one unit cell to one end element electrode portion of the power storage unit via a converter. At the same time, the control unit causes the plurality of switching elements to operate in such a manner that the electrodes on the low-potential sides of the plurality of unit cells are alternately electrically connected to the other end element electrode portion of the power storage unit via the converter. Moreover, the control unit causes the converter to operate in such a manner that power is supplied to the side with the lower voltage between the voltages at both ends of the unit cell and the voltages at both ends of the power storage unit. The control unit can cause the plurality of switching elements to operate in such a manner that the electrodes on the high-potential side and the low-potential side of the unit cell are not connected to the end element electrode portion when performing the second control.

[0045] If configured in this way, when performing the cell equalization operation, each unit cell is alternately connected to the converter by the switching unit, so that one converter can correspond to a plurality of unit cells, and the structure of the power supply device itself can be simplified.

[0046] (9) In the in-vehicle backup power supply device of the present disclosure, the equalization circuit includes a power storage unit composed of one or more power storage elements and a switching unit having a plurality of switching elements. Each switching element corresponds to each unit battery. The electrodes on the high potential side and the low potential side of the unit battery corresponding to the switching element are electrically connected to the converter via the conduction path on the battery unit side. There is a power storage unit switching unit that switches the electrical connection of the electrode portions of the two end elements of the power storage unit to the conduction path on the battery unit side or the conduction path on the load side together. When performing the first control, the control unit operates the power storage unit switching unit so that the electrode portions of the two end elements are electrically connected to the conduction path on the load side together, and electrically connects the electrode of one unit battery on the high potential side to one end element electrode portion of the power storage unit via the converter. At the same time, the control unit operates the plurality of switching elements so that each of the plurality of unit batteries alternately performs the operation of electrically connecting the electrode on the low potential side to the other end element electrode portion of the power storage unit via the converter. Moreover, the control unit operates the converter so that power is supplied to the side with the lower voltage between the voltage across the two ends of the unit battery and the voltage across the two ends of the power storage unit. When performing the second control, the control unit operates the power storage unit switching unit so that the electrode portions of the two end elements are electrically connected to the conduction path on the battery unit side together. The control unit can operate the plurality of switching elements so that the electrodes on the high potential side and the low potential side of the unit battery are not connected to the conduction path on the battery unit side.

[0047] If configured in this way, since the power storage unit switching unit switches the electrical connection of the electrode portions of the two end elements to the conduction path on the battery unit side or the conduction path on the load side together, it is possible to suppress the situation where the power storage unit is connected across the conduction path on the battery unit side and the conduction path on the load side. Thereby, it is possible to suppress malfunction of the converter.

[0048] [Details of the Embodiment of the Present Disclosure]

[0049] <Embodiment 1>

[0050] 〔Structure of the Power Supply Device〕

[0051] The in-vehicle backup power supply device 1 of Embodiment 1 (hereinafter, also referred to as the power supply device 1) is used as a power supply that outputs power for driving an electric drive device (such as a motor) in a vehicle such as a hybrid vehicle or an electric vehicle (EV (Electric Vehicle)). As Figure 1As shown, the power supply device 1 includes a battery unit 10, a discharge circuit 11, a balancing circuit 70, and a control unit 12. The battery unit 10 is formed by electrically connecting a plurality of unit cells 10A in series. The unit cell 10A uses, for example, a lithium-ion storage battery or the like. The battery unit 10 has an inter-battery electrode portion 10B and an end electrode portion 10C. The inter-battery electrode portion 10B is a portion where adjacent unit cells 10A are electrically connected in series. The end electrode portion 10C is an electrode on the high-potential side of the unit cell 10A having the highest potential in the battery unit 10 and an electrode on the low-potential side of the unit cell 10A having the lowest potential in the battery unit 10.

[0052] A power generation device 50 mounted on a vehicle is electrically connected to each of the end electrode portions 10C of the battery unit 10, and a structure is formed in which the battery unit 10 can be charged by the power generation device 50. The power generation device 50 is configured as a known in-vehicle generator and is formed in a structure capable of generating electricity by the rotation of a rotating shaft of an engine (not shown). When the power generation device 50 operates, the power generated by the power generation of the power generation device 50 is rectified and supplied to the battery unit 10 as DC power.

[0053] The discharge circuit 11 includes a plurality of converters 11A. Each converter 11A is configured as a known bidirectional buck-boost DC-DC converter including, for example, a semiconductor switching element and an inductor, and its operation is controlled by the control unit 12. Each converter 11A boosts or buck-boosts the input voltage and outputs it. Each converter 11A is electrically connected to the battery unit 10 via a conductive path on the battery unit side, that is, a first circuit portion 30. The first circuit portion 30 constitutes a power path between the discharge circuit 11 and the battery unit 10. The first circuit portion 30 includes a first conductive path 30A and a second conductive path 30B. Each converter 11A is electrically connected to the electrode on the highest potential side in the battery unit 10 via the first conductive path 30A. Each converter 11A is electrically connected to the electrode on the lowest potential side in the battery unit 10 via the second conductive path 30B. The potential difference between the first conductive path 30A and the second conductive path 30B is input to each converter 11A as an input voltage.

[0054] A first load 51 and a second load 52 are electrically connected to each of the converters 11A via a conductive path on the load side, that is, a third conductive path 31A. The first load 51 and the second load 52 have the same functions, but they are only representative examples and are not limited to this structure. In addition, a conductive path on the load side, that is, a ground path G, is electrically connected to each of the converters 11A.

[0055] The first load 51 is, for example, an electric power steering system configured to receive power supply from the battery unit 10 via a converter 11A and operate electrical components such as a motor. The second load 52 is an electric power steering system having the same structure and function as the first load 51. When an abnormality occurs in the first load 51, the second load 52 operates in place of the first load 51, so that the function of the first load 51 can be maintained even when the first load 51 is abnormal.

[0056] For example, one converter 11A connected to the first load 51 is configured to be able to, when a first condition is satisfied, perform a discharging operation of boosting or reducing the potential difference between the first conductive circuit 30A and the second conductive circuit 30B as an input voltage by the control unit 12 and applying an output voltage to the third conductive circuit 31A. The satisfaction of the first condition means, for example, a case where an ignition switch (not shown) provided in the vehicle is switched from an off state to an on state.

[0057] In addition, when the first load 51 gets into a state where it cannot operate normally, another converter 11A electrically connected to the second load 52 performs a discharging operation through the control unit 12 and supplies power to the second load 52 via the third conductive circuit 31A. The control unit 12 is configured to be able to obtain the voltage value from a detection unit that detects the voltage value and current value of the third conductive circuit 31A connected to the first load 51, and be able to determine whether the first load 51 has got into a state where it cannot operate normally based on this voltage value.

[0058] The balancing circuit 70 has a power storage unit 71 and a switching unit 72. The power storage unit 71 is configured by a plurality of power storage elements 71A that can temporarily store power being electrically connected in series. The power storage element 71A uses, for example, an electric double layer capacitor or the like. The power storage unit 71 has an inter-element electrode part 71B and an end-element electrode part 71C. The inter-element electrode part 71B is the part where adjacent power storage elements 71A are electrically connected in series. The end-element electrode part 71C is the electrode on the high-potential side of the power storage element 71A having the highest potential in the power storage unit 71 and the electrode on the low-potential side of the power storage element 71A having the lowest potential in the power storage unit 71.

[0059] The switching unit 72 includes a plurality of switching elements 72A. For example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are used as the switching elements 72A. Each electrode part of the inter-element electrode part 71B and the end-element electrode part 71C is electrically connected to each switching element 72A one by one. Each switching element 72A corresponds to each unit cell 10A. The switching element 72A is configured such that the control unit 12 electrically connects one of the inter-element electrode part 71B or the end-element electrode part 71C connected to itself to the high-potential side electrode or the low-potential side electrode of the unit cell 10A corresponding to itself. In addition, the switching element 72A can also be made into a non-electrically connected state (hereinafter, also referred to as a non-connected state) between the high-potential side electrode and the low-potential side electrode of the unit cell 10A corresponding to itself and one of the inter-element electrode part 71B or the end-element electrode part 71C connected to itself by the control unit 12.

[0060] The control unit 12 is mainly composed of, for example, a microcomputer, and is configured to have arithmetic devices such as a CPU (Central Processing Unit), memories such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an A / D converter. The control unit 12 is configured to be able to monitor the potential difference between both ends of each unit cell 10A of the battery unit 10 and the connection state of each unit cell 10A at the inter-battery electrode part 10B and the end electrode part 10C. The control unit 12 is configured to be able to monitor the potential difference between both ends of each energy storage element 71A of the energy storage unit 71, etc.

[0061] Next, the operation of the power supply device 1 will be described.

[0062] 〔First discharge operation〕

[0063] When the ignition switch of the vehicle equipped with the power supply device 1 is switched from the off state to the on state, for example, the power supply device 1 supplies power from the battery unit 10 to each converter 11A of the discharge circuit 11 via the first circuit unit 30. The discharge circuit 11 maintains, by the control unit 12, a state in which the operation of one converter 11A electrically connected to the first load 51 starts and the operation of the other converter 11A electrically connected to the second load 52 stops. In this way, one converter 11A performs the first discharge operation of supplying power to the load-side conduction path, that is, the third conduction path 31A.

[0064] In the case where the first load 51 gets into a state where it cannot operate normally, the control unit 12 stops the operation of one converter 11A and starts the operation of the other converter 11A to which the second load 52 is electrically connected. Thereby, the other converter 11A performs a first discharging operation of supplying power to the third conduction path 31A. Specifically, the control unit 12 determines whether the first load 51 has got into a state where it cannot operate normally based on the voltage value from the detection unit that detects the voltage value and current value of the third conduction path 31A connected to the first load 51. When the control unit 12 determines that the first load 51 has got into a state where it cannot operate normally, the control unit 12 stops the operation of one converter 11A and starts the operation of the other converter 11A. In this way, power is supplied to the second load 52 from the other converter 11A.

[0065] 〔Active mode cell equalization operation〕

[0066] The amount of electric power stored in each unit cell 10A of the battery unit 10 depends on the temperature, deterioration state, etc. of each unit cell 10A, and thus there are deviations from each other. To eliminate this deviation, the equalization circuit 70 performs an active mode cell equalization operation (hereinafter, also referred to as cell equalization operation). The control unit performs first control to cause the equalization circuit 70 to perform the cell equalization operation.

[0067] The first control is control for causing the control unit 12 to operate a plurality of switching elements 72A in a manner of alternately repeating a first operation and a second operation. The first operation is an operation in which the control unit 12 electrically connects one of the inter-element electrode portion 71B and the end element electrode portion 71C electrically connected to the switching element 72A to the electrode on the high potential side of the unit cell 10A corresponding to the switching element 72A (see Figure 2 ). And the second operation is an operation in which the control unit 12 electrically connects one of the inter-element electrode portion 71B and the end element electrode portion 71C electrically connected to the switching element 72A to the electrode on the low potential side (see Figure 3 ). And the lengths of the time of these first operations and the lengths of the time of the second operations may be the same as each other, or can be set to different lengths as needed. A certain non-conduction time in which the inter-element electrode portion 71B and the end element electrode portion 71C are in a non-connected state where neither is electrically connected to any of the battery inter-electrode portions 10B and the end electrode portions 10C (see Figure 1 ) is provided between the first operation and the second operation. The length of the non-conduction time can be set as needed.

[0068] When each switching element 72A of the switching unit 72 performs the first operation, except for the unit cell 10A on the lowest potential side of the battery unit 10, each power storage element 71A of the power storage unit 71 is respectively connected in parallel with each unit cell 10A (refer to Figure 2 .). How the charge moves between each unit cell 10A and each power storage element 71A is based on the voltages of both. Specifically, if we focus on one unit cell 10A and one power storage element 71A connected in parallel with this unit cell 10A, when the voltage of the unit cell 10A is higher than the voltage of the power storage element 71A, the charge moves from the unit cell 10A to the power storage element 71A to charge the power storage element 71A. Conversely, when the voltage of the power storage element 71A is higher than the voltage of the unit cell 10A, the charge moves from the power storage element 71A to the unit cell 10A to charge the unit cell 10A. The same applies to other unit cells 10A and other power storage elements 71A connected in parallel with this unit cell 10A.

[0069] On the other hand, when each switching element 72A of the switching unit 72 performs the second operation, except for the unit cell 10A on the highest potential side of the battery unit 10, each power storage element 71A of the power storage unit 71 is respectively connected in parallel with each unit cell 10A (refer to Figure 3 .). The movement of the charge between each unit cell 10A and each power storage element 71A varies according to the magnitudes of the voltages of both. Specifically, if we focus on one unit cell 10A and one power storage element 71A connected in parallel with this unit cell 10A, when the voltage of the unit cell 10A is higher than the voltage of the power storage element 71A, the charge moves from the unit cell 10A to the power storage element 71A to charge the power storage element 71A. Conversely, when the voltage of the power storage element 71A is higher than the voltage of the unit cell 10A, the charge moves from the power storage element 71A to the unit cell 10A to charge the unit cell 10A. The same applies to other unit cells 10A and other power storage elements 71A connected in parallel with this unit cell 10A. In this way, the power supply device 1 alternately repeats the first operation and the second operation of the switching element 72A through the first control of the control unit 12 to perform the unit equalization operation.

[0070] For example, when the control unit 12 determines that the difference in the potential differences across each unit cell 10A reaches below a predetermined value (that is, the potential differences across each unit cell 10A reach the same magnitude), after reaching the state shown in Figure 4 and charging the power storage unit 71 once, the equalization circuit 70 ends the unit equalization operation. When the unit equalization operation ends, each switching element 72A becomes a non-connected state (refer to Figure 1 .). Thus, each power storage element 71A maintains the charged state.

[0071] 〔Second Discharge Operation〕

[0072] When a failure (hereinafter also referred to as a failure state) occurs in which the first discharge operation is not normally performed, the control unit 12 performs second control to cause the balancing circuit 70 to perform a second discharge operation. The failure state means, for example, a situation where the conduction of adjacent unit cells 10A of the battery unit 10 becomes an open circuit state or the unit cell 10A itself cannot discharge normally, etc.

[0073] When it becomes a failure state, as Figure 4 shown, the control unit 12 electrically connects the end electrode portion 10C and the end element electrode portion 71C in the switching element 72A (hereinafter also referred to as the high-potential-side switching element 72A) connected in parallel with the unit cell 10A on the highest potential side. And the control unit 12 electrically connects the end electrode portion 10C and the end element electrode portion 71C in the switching element 72A (hereinafter also referred to as the low-potential-side switching element 72A) connected in parallel with the unit cell 10A on the lowest potential side. In addition, the control unit 12 sets the switching elements 72A other than the high-potential-side switching element 72A and the low-potential-side switching element 72A to a non-connected state. Thereby, the charge stored in the power storage unit 71 is supplied to the discharge circuit 11 via the first circuit unit 30.

[0074] In addition, as Figure 5 shown, when the unit cell 10A on the highest potential side cannot discharge normally, the end electrode portion 10C and the end element electrode portion 71C are electrically connected. At the same time, the control unit 12 can also cause the switching element 72A to operate so that the inter-battery electrode portion 10B adjacent to the end electrode portion 10C and the inter-element electrode portion 71B adjacent to the end element electrode portion 71C are electrically connected. Thereby, the power supply device 1 can form a circuit via the power storage element 71A in a way that bypasses the unit cell 10A that cannot discharge normally, so that each unit cell 10A can be backed up.

[0075] Next, the effects of this structure are illustrated.

[0076] The in-vehicle backup power supply device 1 of the present disclosure is a device in an in-vehicle power supply system that includes a battery unit 10 in which a plurality of unit batteries 10A are connected in series and a discharge circuit 11 that performs a first discharge operation of supplying power to a third conduction path 31A based on the charge stored in the battery unit 10. The in-vehicle backup power supply device 1 of the present disclosure includes a balancing circuit 70 that performs a cell balancing operation on the battery unit 10 and a control unit 12 that controls the balancing circuit 70. The balancing circuit 70 is configured to perform a second discharge operation of supplying power to the third conduction path 31A based on the charge stored in a plurality of power storage elements 71A. The control unit 12 performs a first control for causing the balancing circuit 70 to perform a cell balancing operation and a second control for causing the balancing circuit 70 to perform a second discharge operation. The control unit 12 performs the second control when a failure occurs in which the first discharge operation is not normally performed. Thus, the in-vehicle backup power supply device 1 of the present disclosure can perform a backup operation with a simple structure without providing a dedicated structure for backing up the battery unit 10.

[0077] In the in-vehicle backup power supply device 1 of the present disclosure, the battery unit 10 has an end electrode portion 10C and an inter-battery electrode portion 10B between the unit batteries 10A. The balancing circuit 70 includes a power storage unit 71 in which a plurality of power storage elements 71A are connected in series and a switching unit 72 having a plurality of switching elements 72A. The power storage unit 71 has an end element electrode portion 71C and an inter-element electrode portion 71B between the power storage elements 71A, and each switching element 72A corresponds to each unit battery 10A. The inter-element electrode portion 71B or the end element electrode portion 71C corresponding to the unit battery 10A is electrically connected to the high-potential side electrode or the low-potential side electrode of the unit battery 10A corresponding to the switching element 72A. When performing the first control, the control unit 12 operates each switching element 72A corresponding to each unit battery 10A so that the inter-element electrode portion 71B or the end element electrode portion 71C corresponding to the unit battery 10A is alternately electrically connected to the high-potential side electrode and the low-potential side electrode of the unit battery 10A. When performing the second control, the control unit 12 operates the switching element 72A so that the inter-element electrode portion 71B or the end element electrode portion 71C is electrically connected to each electrode portion of at least two electrode portions of the inter-battery electrode portion 10B and the end electrode portion 10C one by one.

[0078] With such a configuration, since it is a structure in which the inter-element electrode portion 71B or the end element electrode portion 71C is electrically connected to each electrode portion of at least two electrode portions of the inter-battery electrode portion 10B and the end electrode portion 10C one by one. Thus, not only can the battery unit 10 be backed up, but also each unit battery 10A can be backed up.

[0079] The discharge circuit 11 of the in-vehicle backup power supply device 1 of the present disclosure has a converter 11A that boosts or steps down the input voltage and outputs it. When performing the second control, the control unit 12 operates the converter 11A to boost or step down the input voltage based on the power supplied from the power storage element 71A and supply power to the third conduction circuit 31A.

[0080] If configured in this way, it is possible to supply power of a desired magnitude to the third conduction circuit 31A based on the power supplied from the power storage element 71A. In particular, when the power from the power storage element 71A is boosted by the converter 11A, the power stored in the power storage element 71A can be effectively used.

[0081] <Embodiment 2>

[0082] Next, refer to Figure 6 The in-vehicle backup power supply device 2 according to Embodiment 2 (hereinafter, also referred to as the power supply device 2) will be described. The power supply device 2 is different from Embodiment 1 in that it has a plurality of equalization circuits 170, the equalization circuits 170 correspond to each battery group that divides the battery unit 110 into a plurality of unit battery groups 110A and 110B, the structure of the third conduction circuit 131A, the structure of the first circuit unit 130, and the like. The same reference numerals are given to the same structures as those in Embodiment 1, and the description of the structures, operations, and effects is omitted.

[0083] 〔Structure of the power supply device〕

[0084] The battery unit 110 is formed by connecting a plurality of unit batteries 10A in series. The battery unit 110 has a plurality of unit battery groups 110A and 110B.

[0085] Equalization circuits 170 are provided corresponding to each of the unit battery groups 110A and 110B one by one. The structure of the electrical connection between each of the unit battery groups 110A and 110B and the equalization circuit 170 is the same as that in Embodiment 1. The equalization circuit 170 has a power storage unit 171 and a switching unit 172. The power storage unit 171 is different from the power storage unit 71 in Embodiment 1 only in the number of power storage elements 71A and the number of inter-element electrode parts 71B. The switching unit 172 is different from the switching unit 72 in Embodiment 1 only in the number of switching elements 72A.

[0086] Each of the converters 11A is electrically connected to each unit battery pack 110A and 110B of the battery pack 110 one by one via the first circuit unit 130. The first circuit unit 130 constitutes the power path between the discharge circuit 11 and the battery pack 110. The first circuit unit 130 includes a first conduction path 130A and a second conduction path 130B. One converter 11A is electrically connected to the electrode on the highest potential side in the unit battery pack 110A of the battery pack 110 via the first conduction path 130A. One converter 11A is electrically connected to the electrode on the lowest potential side in the unit battery pack 110A of the battery pack 110 via the second conduction path 130B. The other converter 11A is electrically connected to the electrode on the highest potential side in the unit battery pack 110B of the battery pack 110 via the first conduction path 130A. The other converter 11A is electrically connected to the electrode on the lowest potential side in the unit battery pack 110B of the battery pack 110 via the second conduction path 130B. The potential difference between the first conduction path 130A and the second conduction path 130B is input to each converter 11A as the input voltage.

[0087] Each of the converters 11A is electrically connected one by one to a third conduction path 131A, which is a conduction path on the load side. Each converter 11A is electrically connected to a first load 51 and a second load 52 via the third conduction path 131A. The third conduction path 131A has a first load-side switch 131B and a second load-side switch 131C. The first load-side switch 131B and the second load-side switch 131C use, for example, MOSFETs or the like. The first load-side switch 131B is configured to switch the conduction between the converter 11A and the first load 51 between the open state and the closed state by the control unit 12. The second load-side switch 131C is configured to be able to switch the conduction between the converter 11A and the second load 52 between the open state and the closed state by the control unit 12. In addition, a ground path G, which is a conduction path on the load side, is electrically connected to each of the converters 11A.

[0088] Next, the operation of the power supply device 2 will be described.

[0089] 〔First discharge operation〕

[0090] When the ignition switch of the vehicle on which the power supply device 2 is mounted is switched from the off state to the on state, for example, the power supply device 2 supplies power from the battery pack 110 to each converter 11A of the discharge circuit 11 via the first circuit unit 130. The discharge circuit 11 starts the operation of each converter 11A through the control unit 12. In addition, the first load-side switch 131B of each third conduction path 131A becomes the closed state through the control unit 12, and the second load-side switch 131C becomes the open state (not shown) through the control unit 12. In this way, power is supplied from each converter 11A to the first load 51.

[0091] When the control unit 12 determines that the first load 51 has fallen into a state where it cannot operate normally, the control unit 12 causes the first load side switch 131B to change from the closed state to the open state, and causes the second load side switch 131C to change from the open state to the closed state (not shown). In this way, power is supplied to the second load 52 from each converter 11A.

[0092] When the control unit 12 determines, based on the potential difference across each energy storage element 71A of the energy storage unit 71, etc., that a certain one of the equalization circuits 170 has fallen into a state where it cannot operate normally, the control unit 12 stops the operation of the converter 11A corresponding to the equalization circuit 170 that has fallen into the state where it cannot operate normally. At the same time, the control unit 12 causes the first load side switch 131B and the second load side switch 131C of the third conduction path 131A electrically connected to the converter 11A to become open states. At this time, the control unit 12 continues the operation of the converter 11A electrically connected to the other equalization circuit 170. At the same time, the control unit 12 maintains the closed state of the first load side switch 131B and the open state of the second load side switch 131C of the third conduction path 131A electrically connected to the converter 11A. In this way, even if a certain one of the equalization circuits 170 cannot operate normally, the power supply from the converter 11A electrically connected to the other equalization circuit 170 to the first load 51 can be maintained.

[0093] In addition, the determination in the control unit 12 can also be made in the following manner. First, based on the potential difference across each unit cell 10A of the battery unit 110 and the connection states of the unit cells 10A in the inter-battery electrode portion 10B and the end electrode portion 10C, it is determined whether a certain one of the unit battery groups 110A, 110B of the battery unit 110 has fallen into a state where it cannot operate normally. And even when it is determined that a certain one of the unit battery groups 110A, 110B has fallen into a state where it cannot operate normally, the operation of the converter 11A corresponding to a certain one of the unit battery groups 110A, 110B in the state where it cannot operate normally can be stopped.

[0094] 〔Unit equalization operation in the active mode〕

[0095] The unit equalization operation of the equalization circuit 170 in each of the unit battery groups 110A, 110B is the same as that of the equalization circuit 70 in the first embodiment. The control unit 12 performs first control to cause the equalization circuit 170 to perform the unit equalization operation. For example, when the control unit 12 determines that the difference between the potential differences across each unit cell 10A has reached a value equal to or less than a predetermined value (that is, the potential differences across each unit cell 10A have reached the same magnitude), the equalization circuit 170 ends the unit equalization operation. When the unit equalization operation ends, each switching element 72A becomes a non-connected state (see Figure 6.). As a result, each power storage element 71A maintains the power storage state.

[0096] 〔Second Discharge Operation〕

[0097] When the power supply device 2 supplies power from a certain converter 11A to the third conduction path 31A, the first discharge operation can be maintained by maintaining the power supply from the converter 11A to the first load 51. Moreover, when failures occur in both of the unit battery groups 110A and 110B of the battery unit 10, the power supply device 2 performs second control by the control unit 12 to cause the equalization circuit 170 to perform the second discharge operation. The second discharge operation of the equalization circuit 170 in each of the unit battery groups 110A and 110B is the same as the equalization circuit 70 of the first embodiment.

[0098] Next, the effects of this structure are illustrated.

[0099] The in-vehicle backup power supply device 2 of the present disclosure includes a plurality of equalization circuits 170. The battery unit 110 includes a plurality of unit battery groups 110A and 110B. Each of the plurality of unit battery groups 110A and 110B corresponds to a plurality of equalization circuits 170 respectively. The control unit 12 causes each equalization circuit 170 to operate independently.

[0100] If configured in this way, even if one equalization circuit 170 becomes inoperable, the operation of other equalization circuits 170 can continue, so that the backup operation can be performed more reliably.

[0101] <Embodiment 3>

[0102] Next, with reference to Figures 7 - 9 The in-vehicle backup power supply device 3 according to Embodiment 3 (hereinafter, also referred to as the power supply device 3) will be described. The power supply device 3 is different from the second embodiment in the structure of the equalization circuit 270 and the like. The same reference numerals are given to the same structures as those in the second embodiment, and the description of the structures, operations, and effects is omitted.

[0103] 〔Structure of Power Supply Device〕

[0104] The power supply device 3 includes a plurality of equalization circuits 270. Each equalization circuit 270 includes a switching unit 272 and a power storage unit 271. The switching unit 272 includes a plurality of switch groups 272A. Each switch group 272A includes a first switch element 272B and a second switch element 272C. The first switch element 272B and the second switch element 272C use, for example, MOSFETs or the like. The power storage unit 271 is different from the power storage unit 171 of the second embodiment only in that the element-to-element electrode portion 71B is not connected to the switching unit 272.

[0105] Each switch group 272A corresponds to each unit cell 10A. Specifically, each first switch element 272B of the switch group 272A is electrically connected to each electrode on the high-potential side of the unit cell 10A, and each second switch element 272C of the switch group 272A is electrically connected to each electrode on the low-potential side. In each of the unit cell groups 110A and 110B, the electrodes on the high-potential side of each unit cell 10A are electrically connected to the first conduction path 130A of the first circuit section 130 and one end element electrode section 71C of the power storage section 271 via the first switch element 272B. In each of the unit cell groups 110A and 110B, the electrodes on the low-potential side of each unit cell 10A are electrically connected to the second conduction path 130B of the first circuit section 130 and the other end element electrode section 71C of the power storage section 271 via the second switch element 272C.

[0106] The control unit 12 is configured to be able to monitor the potential difference across each unit cell 10A of the battery unit 110 and the connection state of each unit cell 10A at the inter-cell electrode section 10B and the end electrode section 10C. The control unit 12 is configured to be able to monitor the potential difference across each power storage element 71A of the power storage section 271 and the like.

[0107] Next, the operation of the power supply device 3 will be described.

[0108] 〔First discharge operation〕

[0109] When the ignition switch of the vehicle equipped with the power supply device 3 is switched from the off state to the on state, for example, the first switch element 272B connected to the electrode on the high-potential side of each unit cell group 110A and 110B of the battery unit 110 and the second switch element 272C connected to the electrode on the low-potential side are made in the closed state. At the same time, the other first switch elements 272B and second switch elements 272C are made in the open state (refer to Figure 8 .). Thereby, power is supplied from the battery unit 110 to each converter 11A of the discharge circuit 11 via the first circuit section 130. The discharge circuit 11 starts the operation of each converter 11A through the control unit 12. In addition, the first load-side switch 131B of each third conduction path 131A is made in the closed state through the control unit 12, and the second load-side switch 131C is made in the open state through the control unit 12. In this way, power is supplied from each converter 11A to the first load 51.

[0110] 〔Active type cell equalization operation〕

[0111] The control unit 12 performs first control to cause the equalization circuit 270 to perform cell equalization operation. The control unit 12 causes the switching unit 272 to operate in such a manner that all of the switch groups 272A alternately perform an operation in which one of the switch groups 272A in the switching unit 272 of the equalization circuit 270 is selectively brought into a closed state and the other switch groups 272A are brought into an open state (hereinafter, also referred to as an alternative operation) (see Figure 9 .). The switch group 272A being in the closed state means a state in which both the first switching element 272B and the second switching element 272C in the switch group 272A are in the closed state. Further, the switch group 272A being in the open state means a state in which both the first switching element 272B and the second switching element 272C in the switch group 272A are in the open state. The alternative operation in each switch group 272A may have the same time length for each other, or may be set to different time lengths as needed. Further, when performing the alternative operation, a certain non-conduction time during which all the switch groups 272A are in the open state is provided during the period in which the next switch group 272A is switched to the closed state from the currently closed switch group 272A. The length of the non-conduction time can be set as needed.

[0112] When performing the alternative operation in the switching unit 272 of each equalization circuit 270, one unit cell 10A is connected in parallel with the power storage unit 271 (see Figure 9 .). How the charge moves between the unit cell 10A and the power storage unit 271 is based on the voltages of both. Specifically, when the voltage of the unit cell 10A is higher than the voltage of the power storage unit 271, the charge moves from the unit cell 10A to the power storage unit 271 to charge the power storage unit 271. On the contrary, when the voltage of the power storage unit 271 is higher than the voltage of the unit cell 10A, the charge moves from the power storage unit 271 to the unit cell 10A to charge the unit cell 10A. The same applies to the other unit cells 10A and the power storage unit 271 when the other switch groups 272A are in the closed state during the alternative operation. For example, when the control unit 12 determines that the difference in the potential differences across both ends of each unit cell 10A reaches below a predetermined value (that is, the potential differences across both ends of each unit cell 10A reach the same magnitude), the equalization circuit 270 ends the cell equalization operation.

[0113] 〔Second Discharge Operation〕

[0114] The control unit 12 causes the equalization circuit 270 to perform a second discharge operation in the event of a failure state. When a failure state occurs, the control unit 12 brings all of the switch groups 272A of each switching unit 272 into the open state (see Figure 7.). Thus, only the electric charge stored in each power storage unit 271 is supplied to each converter 11A via the first circuit unit 30. Through the second control by the control unit 12, each converter 11A performs a second discharge operation of boosting or reducing the input voltage based on the power from the power storage element 71A and supplying the power to the third conduction path 131A.

[0115] Next, the effects of this structure will be exemplified.

[0116] The discharge circuit 11 of the in-vehicle backup power supply device 3 of the present disclosure has a converter 11A that boosts or reduces the input voltage and outputs it. When performing the second control, the control unit 12 causes the converter 11A to operate to boost or reduce the input voltage based on the power supplied from the power storage element 71A and supply the power to the third conduction path 131A.

[0117] If configured in this way, power of a desired magnitude can be supplied to the third conduction path 131A based on the power from the power storage element 71A. In particular, when the power from the power storage element 71A is boosted by the converter 11A, the power stored in the power storage element 71A can be effectively used.

[0118] In the in-vehicle backup power supply device 3 of the present disclosure, the equalization circuit 270 has a power storage unit 271 composed of one or more power storage elements 71A and a switching unit 272 having a plurality of switch groups 272A. Each switch group 272A corresponds to each unit cell 10A. One end element electrode portion 71C of the power storage unit 271 is electrically connected to the high-potential side electrode of the unit cell 10A corresponding to the switch group 272A. At the same time, the other end element electrode portion 71C of the power storage unit 271 is electrically connected to the low-potential side electrode of the unit cell 10A corresponding to the switch group 272A. When performing the second control, the control unit 12 electrically connects one end element electrode portion 71C of the power storage unit 271 to the high-potential side electrode of one unit cell 10A. At the same time, the control unit 12 causes the plurality of switch groups 272A to operate in such a manner that the low-potential side electrodes of the plurality of unit cells 10A are alternately electrically connected to the other end element electrode portion 71C of the power storage unit 271. When performing the second discharge control, the control unit 12 causes the plurality of switch groups 272A to operate in such a manner that the high-potential side electrode and the low-potential side electrode of the unit cell 10A are not connected to the end element electrode portion 71C.

[0119] If configured in this way, the unit equalization operation can be performed using one power storage element 71A, so that the power supply device 3 itself can be miniaturized.

[0120] <Embodiment 4>

[0121] Next, with reference toFigure 10 , 11 The in-vehicle backup power supply device 4 (hereinafter, also referred to as the power supply device 4) related to Embodiment 4 will be described. The connection positions of the two end element electrode portions 71C of the power storage unit 271 in the power supply device 4 are different from those in Embodiment 3. The same reference numerals are given to the same structures as in Embodiment 3, and the description of the structures, operations, and effects is omitted.

[0122] 〔Structure of the power supply device〕

[0123] Each equalization circuit 370 includes a switching unit 272 and a power storage unit 271. The structures of the switching unit 272 and the power storage unit 271 are the same as those in Embodiment 3. One end element electrode portion 71C of the power storage unit 271 is electrically connected to the discharge circuit 11 side of the third conductive path 31A. The other end element electrode portion 71C of the power storage unit 271 is electrically connected to the conductive path on the load side, that is, the ground path G. Each converter 11A is also electrically connected to the ground path G. The control unit 12 is configured to be able to monitor the potential difference between both ends of each unit cell 10A of the battery unit 110 and the connection states of the unit cells 10A at the inter-cell electrode portion 10B and the end electrode portion 10C. The control unit 12 is configured to be able to monitor the potential difference between both ends of each power storage element 71A of the power storage unit 271, etc.

[0124] Next, the operation of the power supply device 4 will be described.

[0125] 〔First discharge operation〕

[0126] The first discharge operation in the power supply device 4 is the same as that in Embodiment 3.

[0127] 〔Unit equalization operation in the active mode〕

[0128] The control unit 12 performs first control to cause the equalization circuit 370 to perform a unit equalization operation. When an alternative operation is performed in the switching unit 272 of each equalization circuit 370, one unit cell 10A is connected in parallel with the power storage unit 271 via the converter 11A (see Figure 11 .).

[0129] When the control unit 12 determines that the voltage of the unit cell 10A is higher than the voltage of the power storage unit 271, charge moves from the unit cell 10A to the power storage unit 271 via the converter 11A to charge the power storage unit 271. At this time, the converter 11A performs a boosting operation based on the voltage of the unit cell 10A and supplies power to the power storage unit 271, thereby causing the charge to move to the power storage unit 271 earlier.

[0130] Conversely, when the control unit 12 determines that the voltage of the power storage unit 271 is higher than the voltage of the unit cell 10A, charge moves from the power storage unit 271 to the unit cell 10A via the converter 11A to charge the unit cell 10A. At this time, the converter 11A performs a boosting operation based on the voltage of the power storage unit 271 and supplies power to the unit cell 10A, thereby causing the charge to move to the unit cell 10A earlier. For example, when the control unit 12 determines that the difference between the potential differences at both ends of each unit cell 10A reaches a predetermined value or less (i.e., the potential differences at both ends of each unit cell 10A reach the same magnitude), the equalization circuit 370 ends the cell equalization operation.

[0131] 〔Second Discharge Operation〕

[0132] When a failure state occurs, the control unit 12 performs second control to cause the equalization circuit 370 to perform a second discharge operation. In the failure state, as Figure 10 shown, the control unit 12 makes all the switch groups 272A of each switching unit 272 into an open state. Thereby, only the charge stored in each power storage unit 271 is supplied to the first load 51 via the third conduction path 31A.

[0133] Next, the effects of this configuration will be illustrated.

[0134] The discharge circuit 11 of the in-vehicle backup power supply device 4 of the present disclosure has a converter 11A that boosts or steps down the input voltage and outputs it. When performing the first control, the control unit 12 operates the converter 11A to boost or step down the input voltage based on the power supplied from the power storage element 71A and supply power to the battery unit 110.

[0135] If configured in this way, when the equalization circuit 370 performs the cell equalization operation, by boosting the input voltage based on the power from the power storage unit 271 using the converter 11A, it is possible to suppress a decrease in the current flowing between the power storage unit 271 and the battery unit 110 when the cell equalization operation progresses to a certain extent. Thereby, it is possible to actively make the current flow from the power storage unit 271 toward the battery unit 110, and it is possible to make the time required for the equalization operation a shorter time.

[0136] In the in-vehicle backup power supply device 4 of the present disclosure, the equalization circuit 370 includes a power storage unit 271 composed of one or more power storage elements 71A and a switching unit 272 having a plurality of switch groups 272A. Each switch group 272A corresponds to each unit cell 10A. The electrode on the high potential side of the unit cell 10A corresponding to the switch group 272A is electrically connected to one end element electrode portion 71C of the power storage unit 271 via the converter 11A. At the same time, the electrode on the low potential side of the unit cell 10A corresponding to the switch group 272A is electrically connected to the other end element electrode portion 71C of the power storage unit 271 via the converter 11A. When performing the first control, the control unit 12 electrically connects the electrode on the high potential side of one unit cell 10A to one end element electrode portion 71C of the power storage unit 271 via the converter 11A. At the same time, the control unit 12 operates the plurality of switch groups 272A in such a manner that the electrodes on the low potential sides of the plurality of unit cells 10A are alternately electrically connected to the other end element electrode portion 71C of the power storage unit 271. The control unit 12 operates the converter 11A in such a manner that power is supplied to the side with the lower voltage between the voltages at both ends of the unit cell 10A and the voltages at both ends of the power storage unit 271. When performing the second control, the control unit 12 operates the plurality of switch groups 272A in such a manner that the electrodes on the high potential side and the low potential side of the unit cell 10A are not connected to the end element electrode portion 71C.

[0137] If configured in this way, when performing the cell equalization operation, each unit cell 10A is alternately connected to the converter 11A through the switching unit 272. Thereby, one converter 11A can correspond to a plurality of unit cells 10A, and the structure of the power supply device 4 itself can be simplified.

[0138] <Embodiment 5>

[0139] Next, refer to Figures 12 - 14 The in-vehicle backup power supply device 5 according to Embodiment 5 (hereinafter, also referred to as the power supply device 5) will be described. The power supply device 5 is different from Embodiments 3 and 4 in that the connection positions of the two end element electrode portions 71C of the power storage unit 271 are collectively changed by the power storage unit switching unit 273. The same reference numerals are given to the same structures as those in Embodiments 3 and 4, and the description of the structures, operations, and effects is omitted.

[0140] 〔Structure of the power supply device〕

[0141] Each equalization circuit 470 includes a switching unit 272 and a power storage unit 271. The structures of the switching unit 272 and the power storage unit 271 are the same as those in Embodiments 3 and 4. Power storage unit switching units 273 are electrically connected to the two end element electrode portions 71C of the power storage unit 271 one by one. The power storage unit switching unit 273 uses, for example, a MOSFET or the like. The power storage unit switching unit 273 is configured to be able to control its operation through the control unit 12.

[0142] Specifically, the power storage unit switching unit 273 can perform a third operation and a fourth operation. The third operation is an operation in which the control unit 12 electrically connects one end element electrode portion 71C to the first conductive path 130A of the first circuit unit 130 and electrically connects the other end element electrode portion 71C to the second conductive path 130B of the first circuit unit 130 (see Figure 13 ). The fourth operation is an operation in which one end element electrode portion 71C is electrically connected to the third conductive path 31A and the other end element electrode portion 71C is electrically connected to the ground path G (see Figure 14 ). That is, the power storage unit switching unit 273 switches the electrical connection of the two end element electrode portions 71C of the power storage unit 271 to the first circuit unit 130 or the electrical connection to the third conductive path 131A and the ground path G together.

[0143] In addition, the power storage unit switching unit 273 can also make the two end element electrode portions 71C in a state of being not electrically connected to the first circuit unit 130, the third conductive path 31A, and the ground path G (hereinafter, also referred to as a non-connected state) through the control unit 12 (see Figure 12 .).

[0144] Next, the operation of the power supply device 5 will be described.

[0145] 〔First discharge operation〕

[0146] The first discharge operation in the power supply device 5 is the same as that in Embodiment 3.

[0147] 〔Unit equalization operation in the active mode〕

[0148] When each equalization circuit 470 performs a unit equalization operation, the control unit 12 causes the power storage unit switching unit 273 to perform the fourth operation (see Figure 14. ). The control unit 12 performs a first control to make the balancing circuit 470 perform a cell balancing operation. Furthermore, when the control unit 12 causes the switching unit 272 of each balancing circuit 470 to perform a selective operation, one unit cell 10A is connected in parallel with the power storage unit 271 via the converter 11A (not shown). When the voltage of the unit cell 10A is higher than the voltage of the power storage unit 271, the charge is transferred from the unit cell 10A to the power storage unit 271 via the converter 11A to charge the power storage unit 271. At this time, the converter 11A can perform a voltage step-up operation to transfer the charge to the power storage unit 271 earlier.

[0149] Conversely, when the voltage of power storage unit 271 is higher than the voltage of cell 10A, charge is transferred from power storage unit 271 to cell 10A via converter 11A to charge cell 10A. In this case, converter 11A performs a voltage step-up operation to transfer charge to cell 10A earlier.

[0150] For example, when the control unit 12 determines that the potential difference between both ends of each unit cell 10A is less than a predetermined value (that is, the potential difference between both ends of each unit cell 10A is equal in magnitude), the balancing circuit 470 ends the cell balancing operation.

[0151] When the equalizing circuit 470 ends the cell equalizing operation, the storage unit switching unit 273 is in a non-connected state (see Figure 12 . ). Thus, the power storage unit 271 maintains the power storage state.

[0152] [Second discharge action]

[0153] When the failure state is reached, the control unit 12 causes the storage unit switching unit 273 to perform the third operation (see Figure 13 . ). And, all the switch groups 272A of the switching units 272 are turned into an open circuit state. Thus, only the charge stored in each storage unit 271 is supplied to each converter 11A via the first circuit unit 30. Each converter 11A performs the operation of stepping up or down the input voltage based on the power from the storage element 71A and supplying power to the third conductive path 131A by performing the second control by the control unit 12.

[0154] Next, the effects of this structure are exemplified.

[0155] The discharge circuit 11 of the in-vehicle backup power supply device 5 of the present disclosure includes a converter 11A that boosts or steps down the input voltage and outputs it. When performing the first control, the control unit 12 operates the converter 11A to boost or step down the input voltage based on the power supplied from the power storage element 71A and supply the power to the battery unit 110. Further, when performing the second control, the control unit 12 operates the converter 11A to boost or step down the input voltage based on the power supplied from the power storage element 71A and supply the power to the third conduction circuit 131A.

[0156] With such a configuration, when the equalization circuit 470 performs the second discharge operation, it is possible to supply power of a desired magnitude to the third conduction circuit 131A based on the voltage of the power storage unit 271. In particular, when the voltage of the power storage unit 271 is boosted by the converter 11A, the power stored in the power storage unit 271 can be effectively used. Further, when performing the cell equalization operation, by boosting the power from the power storage unit 271 using the converter 11A, a decrease in the current flowing between the power storage unit 271 and the unit cell 10A when the cell equalization operation progresses to a certain extent is suppressed. Moreover, current can be actively exchanged between the power storage unit 271 and the unit cell 10A. As a result, the time required for the equalization operation can be made shorter.

[0157] In the in-vehicle backup power supply device 5 of the present disclosure, the equalization circuit 470 includes a power storage unit 271 composed of one or more power storage elements 71A and a switching unit 272 having a plurality of switch groups 272A. Each switch group 272A corresponds to each unit battery 10A. The high-potential-side electrode and the low-potential-side electrode of the unit battery 10A corresponding to the switch group 272A are electrically connected to the converter 11A via the first circuit unit 130. There is a power storage unit switching unit 273 that switches the electrical connection of the two end element electrode portions 71C of the power storage unit 271 to the first circuit unit 130 or the third conduction path 131A together. When performing the first control, the control unit 12 operates the power storage unit switching unit 273 so that the two end element electrode portions 71C are electrically connected to the third conduction path 131A together. Moreover, the control unit 12 electrically connects the high-potential-side electrode of one unit battery 10A to one end element electrode portion 71C of the power storage unit 271 via the converter 11A. At the same time, the control unit 12 operates the plurality of switch groups 272A so that each of the plurality of unit batteries 10A alternately performs an operation of electrically connecting the low-potential-side electrode to the other end element electrode portion 71C of the power storage unit 271 via the converter 11A. Moreover, the control unit 12 operates the converter 11A so that power is supplied to the side with the lower voltage between the voltages at both ends of the unit battery 10A and the voltages at both ends of the power storage unit 271. When performing the second control, the control unit 12 operates the power storage unit switching unit 273 so that the two end element electrode portions 71C are electrically connected to the first circuit unit 130 together. Moreover, the control unit 12 operates the plurality of switch groups 272A so that the high-potential-side electrode and the low-potential-side electrode of the unit battery 10A are not connected to the first circuit unit 130.

[0158] If configured in this way, by switching the electrical connection of the two end element electrode portions 71C to the first circuit unit 130 or the third conduction path 131A together by the power storage unit switching unit 273, it is possible to suppress the situation where the power storage unit 271 is connected across the first circuit unit 130 and the third conduction path 131A. Thereby, it is possible to suppress malfunction of the converter 11A.

[0159] <Other Embodiments>

[0160] This structure is not limited to the embodiments described above with the accompanying drawings. For example, the following embodiments are also included in the technical scope of the present invention.

[0161] In Embodiments 1 and 2, a structure in which one power storage element 71A corresponds to one unit battery 10A is illustrated, but a structure in which a plurality of power storage elements are connected in series or in parallel may also correspond to one unit battery.

[0162] In Embodiment 1, the control unit 12 is mainly constituted by a microcomputer, but it may also be implemented by a plurality of hardware circuits other than the microcomputer.

[0163] In Embodiments 2 to 5, the number of unit cells 10A in each unit battery pack 110A, 110B of the battery unit 110 is three, but the number of unit cells may also be two, or may be four or more. In addition, the number of unit cells in each unit battery pack may also be different.

[0164] It should be considered that the embodiments disclosed herein are illustrative in all aspects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0165] Description of Reference Numerals

[0166] 1, 2, 3, 4, 5... Vehicle-mounted backup power supply device

[0167] 10, 110... Battery unit

[0168] 10A... Unit cell

[0169] 10B... Inter-cell electrode portion

[0170] 10C... End electrode portion

[0171] 11... Discharge circuit

[0172] 11A... Converter

[0173] 12... Control unit

[0174] 30, 130... First circuit portion (conductive circuit on the battery unit side)

[0175] 30A, 130A... First conductive circuit

[0176] 30B, 130B... Second conductive circuit

[0177] 31A, 131A... Third conductive circuit (conductive circuit on the load side)

[0178] 50... Power generation device

[0179] 51... First load

[0180] 52... Second load

[0181] 70, 170, 270, 370, 470... Balancing circuit

[0182] 71, 171, 271... Power storage unit

[0183] 71A... Power storage element

[0184] 71B…Inter-element electrode part

[0185] 71C…End-element electrode part

[0186] 72, 172, 272…Switching part

[0187] 72A…Switching element

[0188] 110A, 110B…Unit battery pack

[0189] 131B…First load-side switch

[0190] 131C…Second load-side switch

[0191] 272A…Switch group (switching element)

[0192] 272B…First switching element

[0193] 272C…Second switching element

[0194] 273…Power storage part switching part

[0195] G…Ground path (conductive path on the load side).

Claims

1. An in-vehicle backup power supply device, which is an in-vehicle backup power supply device in an in-vehicle power supply system. The in-vehicle backup power supply device includes a battery unit formed by connecting a plurality of unit batteries in series, and a discharge circuit that performs a first discharge operation of supplying power to a conductive path on the load side based on the charge stored in the battery unit. The in-vehicle backup power supply device includes: a balancing circuit, which includes switching elements corresponding to the plurality of unit batteries respectively and performs a cell balancing operation on the battery unit; and a control unit that controls the balancing circuit. The balancing circuit is configured to perform a second discharge operation of supplying power to the conductive path on the load side based on the charge stored in a plurality of energy storage elements. The control unit performs a first control for causing the balancing circuit to perform the cell balancing operation and a second control for causing the balancing circuit to perform the second discharge operation. When a failure occurs in a unit battery where the first discharge operation cannot be normally performed, the control unit controls the switching element corresponding to the unit battery that cannot be normally discharged to form a circuit composed of a unit battery that normally performs the first discharge operation and an energy storage element that bypasses the unit battery that cannot be normally discharged, and supplies power to the conductive path on the load side.

2. The in-vehicle backup power supply device according to claim 1, wherein: the in-vehicle backup power supply device has a plurality of the balancing circuits; the battery unit has a plurality of unit battery groups; each of the plurality of balancing circuits corresponds to each of the plurality of unit battery groups; the control unit causes each of the balancing circuits to operate independently.

3. The in-vehicle backup power supply device according to claim 1 or 2, wherein: the discharge circuit has a converter that boosts or buck-boosts an input voltage and outputs it; when performing the second control, the control unit causes the converter to operate to boost or buck-boost an input voltage based on the power supplied from the energy storage element and apply an output voltage to the conductive path on the load side.

4. The in-vehicle backup power supply device according to claim 1 or 2, wherein: the discharge circuit has a converter that boosts or buck-boosts an input voltage and outputs it; when performing the first control, the control unit causes the converter to operate to boost or buck-boost an input voltage based on the power supplied from the energy storage element and supply power to the battery unit side.

5. The in-vehicle backup power supply device according to claim 1 or 2, wherein: the discharge circuit has a converter that boosts or buck-boosts an input voltage and outputs it; when performing the first control, the control unit causes the converter to operate to boost or buck-boost an input voltage based on the power supplied from the energy storage element and supply power to the battery unit side, and when performing the second control, the control unit causes the converter to operate to boost or buck-boost an input voltage based on the power supplied from the energy storage element and supply power to the conductive path on the load side.

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