Power supply device and method for diagnosing switch

Abstract

The power supply device is configured to be connected between the first DC power supply and the second DC power supply. The power supply device includes: a first switch having one end connected to a first DC power supply; a DC / DC converter having a first capacitance connected to the other end of the first switch; and a control unit configured to control the DC / DC converter and the first switch, and detect a potential difference between one end and the other end of the first switch. The DC / DC converter is configured so as to perform at least one of a first operation for converting the voltage accumulated in the first capacitance to a second voltage and outputting the converted second voltage to the second DC power source, and a second operation for converting the second voltage supplied and held by the second DC power source to a third voltage and outputting the third voltage to the second DC power source. And the converted third voltage is output to the first electrostatic capacitor. The control unit is configured to detect a potential difference after instructing to turn off the first switch and causing the DC / DC converter to perform the first operation or the second operation, and to determine that the first switch is normal when the detected potential difference is greater than a reference potential difference.

Description

Technical Field

[0001] The present disclosure relates to a power supply device connected between two DC power supplies and a method for diagnosing a switch included in the power supply device. Background Art

[0002] Power supply devices that convert power between two DC power sources (a first DC power source and a second DC power source) sometimes include a DC / DC converter that converts the voltage on the input side (i.e., the first DC power source) to a desired voltage and outputs (i.e., charges) it to the output side (i.e., the second DC power source). Such power supply devices typically include switches that connect or disconnect the DC / DC converter between the input-side components and the output-side components to protect the two components connected at both ends. Furthermore, in particular, regarding the disconnection of the switches, after the switches are in the disconnected state, the potential difference between the two ends of the switches is measured to diagnose whether the switches are in a disconnectable state (i.e., whether the switches are normal).

[0003] As a prior art document disclosing such conventional technology, for example, Patent Document 1 is known.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 077958 Summary of the Invention

[0007] In conventional power supply devices, after a switch is in the cutoff state, the potential difference between the two ends of the switch is measured to diagnose the switch's cutting capability. Specifically, if the potential difference between the two ends of the switch is greater than a predetermined potential difference, the switch's cutting capability is diagnosed as normal; otherwise, the switch's cutting capability is diagnosed as abnormal.

[0008] However, when charge is accumulated inside the DC / DC converter (hereinafter, this charge is also referred to as "internal charge"), due to the influence of the voltage accompanying the accumulation of this internal charge, even if the switch can correctly respond to the indication of the disconnection state and disconnect, the potential difference between the two ends of the switch becomes small, and it may not be possible to correctly diagnose the disconnection of the switch.

[0009] To accurately diagnose the switch's off state, leakage current from resistors within the DC / DC converter or the reduction of internal charge due to natural discharge are sometimes used. However, such methods can sometimes require a long time to discharge the DC / DC converter's internal charge, and there's a possibility that diagnosing the switch's off state will require a long wait time.

[0010] In addition, when the voltage on the input side or the output side is maintained by a capacitor, when the voltage on the input side or the output side is equal to the ground potential and the internal voltage of the DC / DC converter is also equal to the ground potential, even if the switch can correctly respond to the indication of the cut-off state and cut off, the potential difference between the two ends of the switch becomes small, making it difficult to diagnose the cut-off capability of the switch based on the potential difference between the two ends of the switch.

[0011] To accurately diagnose the switch's disconnection state, a possible method is to boost the input or output voltage using the power supply, then disconnect the switch. Wait for leakage current from the resistor within the DC / DC converter and for the internal charge to decrease due to natural discharge, and then diagnose the switch's disconnection state. However, this method may require a long time to discharge the internal charge of the DC / DC converter, and there is also the possibility that a long wait time will be required before the power supply starts operating in order to diagnose the switch's disconnection state.

[0012] In view of the above problems, the present disclosure aims to provide a power supply device and a switch diagnosis method capable of quickly diagnosing the interruption performance of a switch provided between the input side or output side and a DC / DC converter included in the power supply device.

[0013] A power supply device according to one embodiment of the present disclosure is connected between a first DC power supply that supplies and maintains a first voltage and a second DC power supply that supplies and maintains a second voltage. The power supply device includes: a first switch having one end connected to the first DC power supply; a DC / DC converter having a first capacitor connected to the other end of the first switch; and a control unit configured to control the DC / DC converter and the first switch and detect a potential difference between one end and the other end of the first switch. The DC / DC converter is configured to perform at least one of a first operation, wherein the first operation converts the voltage stored in the first capacitor into a second voltage and outputs the converted second voltage to the second DC power supply; and a second operation, wherein the second voltage supplied and maintained by the second DC power supply is converted into a third voltage and outputs the converted third voltage to the first capacitor. The control unit is configured to detect the potential difference after instructing the first switch to be disconnected and after the DC / DC converter performs the first operation or the second operation, and to determine that the first switch is normal if the detected potential difference is greater than a reference potential difference.

[0014] In the power supply device diagnostic method according to one aspect of the present disclosure, after the switch is instructed to be disconnected and the DC / DC converter performs the first operation or the second operation, the potential difference between the first end and the other end of the switch is detected. If the detected potential difference is greater than a reference potential difference, the switch is determined to be normal.

[0015] According to the present disclosure, a power supply device and a switch diagnosis method are provided that can quickly diagnose the interruption performance of a switch provided between an input side or an output side and a DC / DC converter included in the power supply device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1A It is a diagram showing the configuration of a power supply device according to an embodiment.

[0017] Figure 1B This is a diagram showing a flowchart of a process for diagnosing the interruption performance of the first switch during the operation of the power supply device according to the embodiment.

[0018] Figure 1C This is a diagram showing a flowchart of a process for diagnosing the interruption performance of the second switch during the operation of the power supply device according to the embodiment.

[0019] Figure 2 It is a diagram showing a configuration example of a power supply device according to Modification 1 of the embodiment.

[0020] Figure 3 It is a diagram showing a configuration example of a power supply device according to a second modification of the embodiment.

[0021] Figure 4 It is a diagram showing a configuration example of a power supply device according to a third modification of the embodiment.

[0022] Figure 5 It is a diagram showing a configuration example of a power supply device according to a fourth modification of the embodiment.

[0023] Figure 6 It is a diagram showing a configuration example of a power supply device according to a fifth modification of the embodiment.

[0024] Figure 7 This is a diagram illustrating a circuit of a DC / DC converter in a first specific example of a power supply device according to an embodiment.

[0025] Figure 8 This is a diagram illustrating a circuit of a DC / DC converter in a second specific example of the power supply device according to the embodiment.

[0026] Figure 9 This is a diagram illustrating a circuit of a DC / DC converter in a third specific example of the power supply device according to the embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the power supply device of the present disclosure will be described with reference to the accompanying drawings. The embodiments disclosed below are merely examples and are not intended to limit the power supply device of the present disclosure.

[0028] In addition, in the embodiments disclosed below, detailed descriptions beyond those necessary may be omitted. For example, detailed descriptions of known matters and repetitive descriptions of substantially identical components may be omitted. This is to avoid unnecessary and lengthy descriptions and facilitate understanding for those skilled in the art. Furthermore, "A and B are connected" means that A and B are electrically connected, encompassing not only direct connections between A and B but also indirect connections with other circuit elements interposed between A and B.

[0029] Figure 1A 1 is a block diagram showing the configuration of the power supply device 1 according to the embodiment. In this embodiment, the power supply device 1 is mounted on a vehicle 100. Figure 1A As shown, the power supply device 1 of the embodiment includes a first DC power supply 2, a second DC power supply 3, a DC / DC converter 4, a first switch 5, a second switch 6, a control unit 7 having a diagnostic unit 8, a first voltage detection unit 51, a second voltage detection unit 52, a third voltage detection unit 61 and a fourth voltage detection unit 62.

[0030] Here, for ease of explanation, the control unit 7 includes the diagnostic unit 8 , but the control unit 7 and the diagnostic unit 8 may be independent components. Furthermore, the first voltage detection unit 51 , the second voltage detection unit 52 , the third voltage detection unit 61 , and the fourth voltage detection unit 62 may be built into the diagnostic unit 8 .

[0031] The first DC power source 2 can output (ie, supply and maintain) a first voltage, and is, for example, a battery. The second DC power source 3 can output (ie, supply and maintain) a second voltage, and is, for example, an electric double layer capacitor.

[0032] A DC / DC converter 4 is connected between the first DC power supply 2 and the second DC power supply 3. The DC / DC converter 4 includes a first electrostatic capacitor 91 capable of storing a first voltage, a second electrostatic capacitor 92 capable of storing a second voltage, a current sensor 42 for measuring the current flowing through the DC / DC converter 4, and a power conversion circuit 41 for performing DC voltage conversion to step down the first voltage to the second voltage and to step up the second voltage to the first voltage.

[0033] The DC / DC converter 4 steps down the first voltage input from the first DC power supply 2 and outputs the stepped-down voltage to the second DC power supply 3. Furthermore, the DC / DC converter 4 steps up the second voltage input from the second DC power supply 3 and outputs the stepped-up voltage to the first DC power supply 2. In this embodiment, the DC / DC converter 4 steps down the first voltage input from the first DC power supply 2 and outputs it to the second DC power supply 3, and steps up the second voltage input from the second DC power supply 3 and outputs it to the first DC power supply 2. Conversely, the DC / DC converter 4 may step up the first voltage input from the first DC power supply 2 and output it to the second DC power supply 3, and step down the second voltage input from the second DC power supply 3 and output it to the first DC power supply 2.

[0034] Furthermore, a first switch 5 is connected between the first DC power source 2 and the DC / DC converter 4 , and can connect and disconnect the first DC power source 2 and the DC / DC converter 4 .

[0035] Furthermore, a second switch 6 is connected between the second DC power source 3 and the DC / DC converter 4 , and can connect and disconnect the second DC power source 3 and the DC / DC converter 4 .

[0036] The first switch 5 and the second switch 6 are, for example, semiconductor switches represented by metal oxide field effect transistors (MOSFETs), contactors represented by electromagnetic relays, and the like.

[0037] The first voltage detection unit 51 , the second voltage detection unit 52 , the third voltage detection unit 61 , and the fourth voltage detection unit 62 are voltmeters, such as analog / digital (A / D) converters.

[0038] The control unit 7 can instruct the DC / DC converter 4 to perform step-down control (i.e., step down the first voltage and output it to the second DC power supply 3) or step-up control (i.e., step up the second voltage and output it to the first DC power supply 2). Furthermore, the control unit 7 can instruct the first switch 5 to connect or disconnect the first DC power supply 2 and the DC / DC converter 4. Furthermore, the control unit 7 can instruct the second switch 6 to connect or disconnect the second DC power supply 3 and the DC / DC converter 4.

[0039] Furthermore, the control unit 7 can cause the diagnosis unit 8 to measure the voltage across both ends of the first switch 5 or the potential difference between the both ends.

[0040] Thus, when it is desired to diagnose the disconnection performance of the first switch 5, after the control unit 7 issues a disconnection instruction to the first switch 5 and a connection instruction to the second switch 6, the DC / DC converter 4 performs a voltage conversion operation to discharge the charge in the first electrostatic capacitor 91 to the second DC power supply 3. Thus, it is possible to provide a power supply device 1 that can diagnose the disconnection performance of the first switch 5 in a short period of time.

[0041] The control unit 7 and the diagnosis unit 8 are implemented by a memory storing programs, a processor executing the programs, an A / D converter, a timer, and the like.

[0042] Next, the overall operation of the power supply device 1 will be described.

[0043] First, the normal voltage conversion operation is described. Normal voltage conversion operation refers to the operation of stepping down the first voltage of the first DC power supply 2 to the second voltage and outputting it to the second DC power supply 3, and the operation of stepping up the second voltage of the second DC power supply 3 to the first voltage and outputting it to the first DC power supply 2.

[0044] For example, when vehicle 100 equipped with power supply device 1 has started to start, or when vehicle 100 is starting, control unit 7 instructs first switch 5 to connect first DC power supply 2 and DC / DC converter 4. Furthermore, control unit 7 instructs second switch 6 to connect second DC power supply 3 and DC / DC converter 4.

[0045] The first switch 5 connects the first DC power supply 2 to the DC / DC converter 4 based on an instruction from the control unit 7 . The second switch 6 connects the second DC power supply 3 to the DC / DC converter 4 based on an instruction from the control unit 7 .

[0046] The voltage input from the first DC power supply 2 or the second DC power supply 3 to the DC / DC converter 4 is converted to a voltage based on a signal from the control unit 7 to the DC / DC converter 4. At this time, the first electrostatic capacitor 91 is charged to the first voltage of the first DC power supply 2. Furthermore, the second electrostatic capacitor 92 is charged to the second voltage of the second DC power supply 3.

[0047] Next, an operation of diagnosing the function of disconnecting from the outside after the normal voltage conversion operation described above is performed will be described.

[0048] First, a case of diagnosing the interruption performance of the first switch 5 will be described.

[0049] Figure 1B This is a flowchart of a process for diagnosing the interruption performance of the first switch 5 during the operation of the power supply device 1 according to the embodiment (ie, a switch diagnosis method).

[0050] The control unit 7 instructs the first switch 5 to disconnect the first DC power supply 2 and the DC / DC converter 4. Based on the instruction from the control unit 7, the first switch 5 is instructed to disconnect, thereby disconnecting the first DC power supply 2 and the DC / DC converter 4 (S10).

[0051] In addition, the control unit 7 instructs the second switch 6 to connect the second DC power supply 3 and the DC / DC converter 4. The second switch 6 connects the second DC power supply 3 and the DC / DC converter 4 based on the instruction from the control unit 7 (S11). The order of steps S10 and S11 can be the same as Figure 1B The order shown is reversed and simultaneous is also possible.

[0052] Next, the control unit 7 operates the DC / DC converter 4 to discharge the charge stored in the first electrostatic capacitor 91 of the DC / DC converter 4 to the second DC power supply 3 (S12). Specifically, the control unit 7 instructs the DC / DC converter 4 to perform a voltage step-down operation to discharge the charge stored in the first electrostatic capacitor 91 of the DC / DC converter 4 to the second DC power supply 3.

[0053] Next, the diagnostic unit 8 measures the voltages at both ends of the first switch 5, detected by the first voltage detection unit 51 and the second voltage detection unit 52, and calculates the potential difference between the two ends of the first switch 5 (S13). If the potential difference between the two ends of the first switch 5 calculated by the diagnostic unit 8 is not greater than the reference value (No in S14), it can be confirmed that the first switch 5 is unable to disconnect the first DC power supply 2 and the DC / DC converter 4, and the first switch 5 is determined to be abnormal (S15). Alternatively, if the potential difference between the two ends of the first switch 5 calculated by the diagnostic unit 8 is greater than the reference value (Yes in S14), it can be confirmed that the first switch 5 is able to disconnect the first DC power supply 2 and the DC / DC converter 4, and the first switch 5 is determined to be normal (S16). This allows determination of whether the disconnection function of the first switch 5 is operating normally. Based on the determination result of whether the first switch 5 is operating normally, the control unit 7 outputs a determination signal to, for example, an electronic control unit (ECU) mounted in the vehicle 100. The ECU performs actions (display, control, etc.) in accordance with the determination signal.

[0054] Thus, in this embodiment, when the control unit 7 instructs the first switch 5 to disconnect the first DC power supply 2 and the DC / DC converter 4, the control unit 7 causes the DC / DC converter 4 to discharge the charge stored in the first electrostatic capacitor 91 connected between the first switch 5 and ground in the DC / DC converter 4. Consequently, when the first switch 5 is disconnected, the potential difference across the first switch 5 can be increased compared to a case where the charge is not discharged, allowing the diagnostic unit 8 to easily and reliably perform a diagnosis of the first switch 5.

[0055] Here, when the control unit 7 instructs the first switch 5 to disconnect the first DC power supply 2 and the DC / DC converter 4, the charge stored in the first electrostatic capacitor 91 remains. In other words, only the first switch 5 is disconnected. At this time, when the diagnostic unit 8 measures the potential difference between the two ends of the first switch 5, the residual charge in the first electrostatic capacitor 91 causes the potential difference between the two ends of the first switch 5 to be smaller than that of the power supply device 1 of the present disclosure, even if the first switch 5 is normally disconnected. Therefore, the diagnostic unit 8 cannot determine whether the first switch 5 is normally disconnected.

[0056] Furthermore, the charge in the first electrostatic capacitor 91 is naturally released over time through leakage current from the parallel-connected resistor and DC / DC converter 4. Therefore, by measuring the potential difference between the two terminals of the first switch 5 after a certain period of time, it is possible to determine whether the first switch 5 has been properly disconnected. However, in the power supply device 1 of the present disclosure, after the control unit 7 instructs the first switch 5 to disconnect the first DC power supply 2 and the DC / DC converter 4, the control unit 7 instructs the DC / DC converter 4 to perform voltage conversion, thereby actively discharging the charge in the first electrostatic capacitor 91 in a short period of time. As a result, the charge in the first electrostatic capacitor 91 can be discharged in a very short period of time compared to natural discharge, and therefore, it is possible to determine whether the first switch 5 has been properly disconnected in a shorter period of time compared to natural discharge.

[0057] Next, a case of diagnosing the interruption performance of the second switch 6 will be described.

[0058] Figure 1C This is a flowchart of a process for diagnosing the interruption performance of the second switch 6 (ie, a switch diagnosis method) during the operation of the power supply device 1 according to the embodiment.

[0059] The control unit 7 instructs the second switch 6 to disconnect the second DC power supply 3 and the DC / DC converter 4. Based on the instruction from the control unit 7, the second switch 6 is instructed to disconnect, thereby disconnecting the second DC power supply 3 and the DC / DC converter 4 (S20).

[0060] In addition, the control unit 7 instructs the first switch 5 to connect the first DC power supply 2 and the DC / DC converter 4. The first switch 5 connects the first DC power supply 2 and the DC / DC converter 4 based on the instruction from the control unit 7 (S21). The order of steps S20 and S21 can be the same as Figure 1C The order shown can be reversed or simultaneous.

[0061] Next, the control unit 7 operates the DC / DC converter 4 to discharge the charge stored in the second electrostatic capacitor 92 of the DC / DC converter 4 to the first DC power supply 2 (S22). Specifically, the control unit 7 instructs the DC / DC converter 4 to perform a step-up operation to discharge the charge stored in the second electrostatic capacitor 92 of the DC / DC converter 4 to the first DC power supply 2.

[0062] Next, the diagnostic unit 8 measures the voltages at both ends of the second switch 6 and at two points detected by the third voltage detection unit 61 and the fourth voltage detection unit 62, thereby calculating the potential difference between the two ends of the second switch 6 (S23). If the potential difference between the two ends of the second switch 6 calculated by the diagnostic unit 8 is not greater than the reference value (No in S24), it can be confirmed that the second switch 6 cannot disconnect the second DC power supply 3 from the DC / DC converter 4, and it is determined that the second switch 6 is not operating normally and is abnormal (S25). Alternatively, if the potential difference between the two ends of the second switch 6 measured by the diagnostic unit 8 is greater than the reference value (Yes in S24), it can be confirmed that the second switch 6 can disconnect the second DC power supply 3 from the DC / DC converter 4, and it is determined that the second switch 6 is operating normally (S26). If the potential difference between the two ends of the second switch 6 measured by the diagnostic unit 8 is not greater than the reference value (No in S24), it can be confirmed that the second switch 6 cannot disconnect the second DC power supply 3 from the DC / DC converter 4, and it is determined that the second switch 6 is not operating normally and is abnormal (S26). This allows for determination of whether the shutoff function of the second switch 6 is operating normally. Based on the determination of whether the second switch 6 is operating normally, the control unit 7 outputs a determination signal to, for example, an electronic control unit (ECU) mounted on the vehicle 100. The ECU performs actions (such as display and control) in accordance with the determination signal.

[0063] Thus, in this embodiment, when the control unit 7 instructs the second switch 6 to disconnect the second DC power supply 3 and the DC / DC converter 4, the control unit 7 causes the DC / DC converter 4 to discharge the charge stored in the second electrostatic capacitor 92 connected between the second switch 6 and the ground in the DC / DC converter 4. Thus, when the second switch 6 is disconnected, the potential difference across the second switch 6 can be increased compared to a case where the charge is not discharged, and the diagnostic unit 8 can easily and reliably perform a diagnosis of the second switch 6.

[0064] Here, when the control unit 7 instructs the second switch 6 to disconnect the second DC power supply 3 and the DC / DC converter 4, the charge stored in the second electrostatic capacitor 92 remains. In other words, only the second switch 6 is disconnected. At this time, when the diagnostic unit 8 measures the potential difference between the two ends of the second switch 6, the residual charge in the second electrostatic capacitor 92 causes the potential difference between the two ends of the second switch 6 to be smaller than that of the power supply device 1 of the present disclosure, even if the second switch 6 is normally disconnected. Therefore, the diagnostic unit 8 cannot determine whether the second switch 6 is normally disconnected.

[0065] Furthermore, conventionally, the charge in second electrostatic capacitor 92 is naturally released over time through leakage current from the parallel-connected resistor and DC / DC converter 4. Therefore, after a certain period of time, the potential difference between the two terminals of second switch 6 is measured to determine whether second switch 6 has been properly disconnected. However, in the power supply device 1 of the present disclosure, after control unit 7 instructs second switch 6 to disconnect second DC power supply 3 and DC / DC converter 4, control unit 7 instructs DC / DC converter 4 to perform voltage conversion, thereby actively discharging the charge in second electrostatic capacitor 92 in a short period of time. This allows the charge in second electrostatic capacitor 92 to be discharged in a much shorter time than would be possible through natural discharge, making it possible to determine whether second switch 6 has been properly disconnected in a shorter time than conventional methods.

[0066] In addition, each reference value of the potential difference between both ends of the first switch 5 and the second switch 6 is determined based on the cutoff characteristics of the elements or components used for the first switch 5 and the second switch 6 .

[0067] Furthermore, first DC power source 2 can be replaced by a capacitor. The first voltage does not necessarily need to be supplied from an active power source; the capacitor can be charged by DC / DC converter 4, and the charged voltage can be used as the first voltage. This allows the power supply for vehicle 100 to consist solely of second DC power source 3, achieving a vehicle configuration that is advantageous in terms of cost, component placement, and weight.

[0068] Furthermore, second DC power supply 3 can be replaced by a capacitor. The second voltage does not necessarily need to be supplied from an active power source; the capacitor can be charged by DC / DC converter 4, and the charged voltage can be used as the second voltage. This allows the power supply for vehicle 100 to consist solely of first DC power supply 2, achieving a vehicle configuration that is advantageous in terms of cost, component placement, and weight.

[0069] In addition, if Figure 2 As in the configuration example of the power supply device 1a of the modification 1 of the embodiment shown in FIG. Figure 1AIn addition to the first voltage detection unit 51 and the second voltage detection unit 52, a fifth voltage detection unit 53 is provided for directly measuring the potential difference between both ends of the first switch 5. The fifth voltage detection unit 53 is, for example, an A / D converter.

[0070] Likewise, Figure 2 As shown, you can also replace Figure 1A In addition to the third voltage detection unit 61 and the fourth voltage detection unit 62, a sixth voltage detection unit 63 is provided for directly measuring the potential difference between both ends of the second switch 6. The sixth voltage detection unit 63 is, for example, an A / D converter.

[0071] In addition, in the embodiment, the DC / DC converter 4 can also operate to control the voltage of the first electrostatic capacitor 91 when diagnosing the disconnection performance of the first switch 5. Specifically, after the control unit 7 instructs the first switch 5 to disconnect the first DC power supply 2 and the DC / DC converter 4, the control unit 7 instructs the DC / DC converter 4 to convert the voltage. At this time, by using Figure 1A The voltage of the first electrostatic capacitor 91 is controlled based on the voltage of the first electrostatic capacitor 91 detected by the second voltage detection unit 52, and the voltage of the first electrostatic capacitor 91 can be controlled (ie, set) to an arbitrary voltage.

[0072] When the first switch 5 is connected, in order to reduce the inrush current flowing through the first switch 5 during connection, the first electrostatic capacitor 91 is charged to a voltage close to the first DC power supply 2 before the first switch 5 is connected.

[0073] Therefore, when determining whether the cutoff function of the first switch 5 is operating normally, the charge of the first electrostatic capacitor 91 is completely discharged. When the first switch 5 is connected again, the first electrostatic capacitor 91 is charged to the voltage of the first DC power supply 2.

[0074] On the other hand, when the voltage of the first electrostatic capacitor 91 is controlled to a voltage other than zero, the charging time when the first switch 5 is connected again can be shortened.

[0075] For example, when the voltage of the first electrostatic capacitor 91 is controlled to a voltage other than zero, the voltage is monitored by the first voltage detection unit 51, and control is performed so that the potential difference required to determine whether the shutoff function of the first switch 5 is operating normally is maintained relative to the voltage of the second voltage detection unit 52. Thus, for example, by controlling the voltage of the first electrostatic capacitor 91 to a voltage that is lower than the first voltage by a reference value for determination, the charge released from the first electrostatic capacitor 91 can be minimized to determine whether the shutoff function of the first switch 5 is operating normally. This can shorten the time required to determine the shutoff function and the charging time required when the first switch 5 is reconnected.

[0076] Similarly, when diagnosing the disconnection performance of the second switch 6, the DC / DC converter 4 can also operate to control the voltage of the second electrostatic capacitor 92. Specifically, after the control unit 7 instructs the second switch 6 to disconnect the second DC power supply 3 and the DC / DC converter 4, the control unit 7 instructs the DC / DC converter 4 to convert the voltage. In this case, by controlling the voltage of the second electrostatic capacitor 92 using the voltage detected by the third voltage detection unit 61, the voltage of the second electrostatic capacitor 92 can be controlled (i.e., set) to an arbitrary voltage.

[0077] When the second switch 6 is connected, in order to reduce the inrush current flowing through the second switch 6 during connection, the second electrostatic capacitor 92 is charged to a voltage close to the second DC power supply 3 before the second switch 6 is connected.

[0078] Therefore, when determining whether the cutoff function of the second switch 6 is operating normally, the charge of the second electrostatic capacitor 92 is completely discharged. When the second switch 6 is connected again, the second electrostatic capacitor 92 is charged to the voltage of the second DC power supply 3.

[0079] On the other hand, when the voltage of the second electrostatic capacitor 92 is controlled to a voltage other than zero, the charging time when the second switch 6 is connected again can be shortened.

[0080] For example, when the voltage of the second electrostatic capacitor 92 is controlled to a voltage other than zero, the fourth voltage detection unit 62 monitors this voltage, thereby controlling the voltage to maintain a potential difference with respect to the voltage of the third voltage detection unit 61 required for determining whether the shutoff function of the second switch 6 is operating normally. Thus, for example, by controlling the voltage of the second electrostatic capacitor 92 to a voltage that is lower than the second voltage by a reference value for determination, the charge released from the second electrostatic capacitor 92 can be minimized to determine whether the shutoff function of the second switch 6 is operating normally. This can shorten the time required to determine the shutoff function and the charging time required when the second switch 6 is reconnected.

[0081] Furthermore, the diagnostic unit 8 may detect the current flowing through the power conversion circuit 41 of the DC / DC converter 4 using the current sensor 42. After the control unit 7 instructs the first switch 5 to disconnect the first DC power source 2 from the DC / DC converter 4, or after the control unit 7 instructs the second switch 6 to disconnect the second DC power source 3 from the DC / DC converter 4, the control unit 7 instructs the DC / DC converter 4 to perform voltage conversion. At this time, the DC / DC converter 4 performs current control so that the current detected by the current sensor 42 falls below a predetermined current, or detects that the current exceeds the predetermined current and stops the DC / DC converter 4 from converting the current. This prevents excessive power from being supplied to the first DC power source 2 or the second DC power source 3, or prevents excessive current from flowing to the second DC power source 3, even if the disconnection performance of the first switch 5 or the second switch 6 being diagnosed is lost.

[0082] In addition, if Figure 3 As in the configuration example of the power supply device 1b of the variant example 2 of the embodiment shown, in the power supply device 1b which does not have the second switch 6 in the embodiment but is composed only of the first switch 5, and the DC / DC converter 4a is composed only of the first electrostatic capacitor 91 and the power conversion circuit 41, the disconnection performance of the first switch 5 can also be diagnosed.

[0083] Likewise, Figure 4 As in the configuration example of the power supply device 1c of the variant example 3 of the embodiment shown, in a power supply device that does not have a first switch 5 but is composed only of a second switch 6, and in which the DC / DC converter 4b is composed only of a second electrostatic capacitor 92 and a power conversion circuit 41, the disconnection performance of the second switch 6 can also be diagnosed.

[0084] In addition, if Figure 5 Even when the first switch 5a and the second switch 6a are each composed of a single MOSFET, as in the configuration example of the power supply device 1d of the fourth modification of the embodiment shown, the cutoff performance of the first switch 5a and the second switch 6a can be diagnosed by the same method as in the above embodiment.

[0085] The first switch 5a is formed of a MOSFET having a body diode as shown in the figure, with the direction from the DC / DC converter 4 toward the first DC power supply 2 as the forward direction. Therefore, it has the function of blocking the current flowing from the first DC power supply 2 to the DC / DC converter 4, but does not have the function of blocking the current flowing from the DC / DC converter 4 to the first DC power supply 2. Even with such a first switch 5a, in the embodiment, the voltage of the first electrostatic capacitor 91 is reduced after the first switch 5a is turned off during the diagnosis of the blocking performance, so the blocking performance of the first switch 5a can be diagnosed.

[0086] Similarly, the second switch 6a is formed of a MOSFET having a body diode as shown in the figure, with the direction from the DC / DC converter 4 toward the second DC power supply 3 as the forward direction. Therefore, it has the function of blocking the current flowing from the second DC power supply 3 to the DC / DC converter 4, but does not have the function of blocking the current flowing from the DC / DC converter 4 to the second DC power supply 3. Even with such a second switch 6a, in the embodiment, the voltage of the second electrostatic capacitor 92 is reduced after the second switch 6a is turned off, so the blocking performance of the second switch 6a can be diagnosed.

[0087] Figure 6 It is a diagram showing a configuration example of a power supply device 1e according to a fifth modification of the embodiment.

[0088] The power supply device 1e includes a first DC power supply 2, a second DC power supply 3, a DC / DC converter 4, a first switch 5b, a second switch 6b, a control unit 7a including a diagnostic unit 8, a first voltage detection unit 51, a second voltage detection unit 52, a third voltage detection unit 61, and a fourth voltage detection unit 62. Components identical to those in the embodiment are denoted by the same reference numerals, and description thereof is omitted. The description will focus on differences from the above embodiment.

[0089] like Figure 6 As shown, the first switch 5b is composed of two MOSFETs with body diodes in opposite forward directions connected in series, and has the function of cutting off current in both directions. Figure 6 As shown, the second switch 6b is composed of two MOSFETs having body diodes with mutually opposite forward directions connected in series, and has a function of blocking current in both directions.

[0090] In addition to the functions described in the embodiment, the control unit 7a and the DC / DC converter 4 have the following functions in this modification.

[0091] That is, in the diagnosis of the first switch 5b, after the control unit 7a issues a disconnection instruction to the first switch 5b, the DC / DC converter 4 performs voltage conversion to boost the voltage of the second electrostatic capacitor 92 and output it to the first electrostatic capacitor 91, thereby charging the first electrostatic capacitor 91.

[0092] Furthermore, during the diagnosis of the second switch 6 b , after the control unit 7 a issues a shutoff instruction to the second switch 6 b , the DC / DC converter 4 performs voltage conversion to step down the voltage of the first electrostatic capacitor 91 and output the voltage to the second electrostatic capacitor 92 , thereby charging the second electrostatic capacitor 92 .

[0093] Therefore, a power supply device 1e can be provided that can diagnose the disconnection performance of the first switch 5b that disconnects the first DC power supply 2 and the DC / DC converter 4, and the second switch 6b that disconnects the second DC power supply 3 and the DC / DC converter 4 in a short time.

[0094] Next, the overall operation of the power supply device 1e will be described.

[0095] In addition, the normal voltage conversion operation is the same as that in the embodiment.

[0096] The operation in the case where the connection with the outside is cut off after the normal voltage conversion operation is performed will be described.

[0097] The control unit 7a instructs the first switch 5b to disconnect the first DC power supply 2 and the DC / DC converter 4. Based on the instruction from the control unit 7a, the first switch 5b disconnects the first DC power supply 2 and the DC / DC converter 4. At this time, for example, the control unit 7a further switches the target of voltage detection and monitoring to the first electrostatic capacitor 91, and detects and monitors the voltage of the first electrostatic capacitor 91.

[0098] Next, the control unit 7a controls the DC / DC converter 4 so that the voltage of the first electrostatic capacitor 91 of the DC / DC converter 4 is higher than the voltage of the first DC power supply 2. Specifically, the control unit 7a instructs the DC / DC converter 4 to perform a voltage boost operation, causing the DC / DC converter 4 to boost the voltage of the second DC power supply 3 so that the voltage of the first electrostatic capacitor 91 is higher than that of the first DC power supply 2. In this case, by setting the first electrostatic capacitor 91 as the target of power conversion, the existing DC / DC converter 4 can control the voltage of the first electrostatic capacitor 91 to any voltage greater than zero.

[0099] Next, the diagnostic unit 8 measures the potential difference between the two ends of the first switch 5b. If the potential difference between the two ends of the first switch 5b measured by the diagnostic unit 8 is less than a reference value, it can be confirmed that the first switch 5b is unable to disconnect the first DC power supply 2 and the DC / DC converter 4 while failing to properly respond to the instruction from the control unit 7a. Alternatively, if the potential difference between the two ends of the first switch 5b measured by the diagnostic unit 8 is greater than the reference value, it can be confirmed that the first switch 5b is able to disconnect the first DC power supply 2 and the DC / DC converter 4 while being able to respond to the instruction from the control unit 7a. This makes it possible to determine whether the first switch 5b is able to properly disconnect the first DC power supply 2 and the DC / DC converter 4.

[0100] Here, Figure 5The first switch 5a of the fourth modification shown is composed of a single MOSFET. Therefore, generally speaking, even when the first switch 5a is controlled to the off state, it does not have the capability to cut off the current flowing from the DC / DC converter 4 to the first DC power supply 2 through the body diode. Therefore, only the current flowing from the first DC power supply 2 to the DC / DC converter 4 is cut off. Figure 6 As shown in the first switch 5b of this variant example, when it has the performance of cutting off the current flowing from the DC / DC converter 4 to the first DC power supply 2, the method of this variant example can diagnose the performance of cutting off the current flowing from the DC / DC converter 4 to the first DC power supply 2.

[0101] In addition, in the above-mentioned description of the action in the case of cutting off the connection with the outside, the control unit 7a instructs the first switch 5b to cut off the first DC power supply 2 and the DC / DC converter 4, but the same action is also performed when the control unit 7a instructs the second switch 6b to cut off the second DC power supply 3 and the DC / DC converter 4.

[0102] That is, the control unit 7a instructs the second switch 6b to disconnect the second DC power supply 3 and the DC / DC converter 4. Based on the instruction from the control unit 7a, the second switch 6b disconnects the second DC power supply 3 and the DC / DC converter 4. For example, at this time, the control unit 7a further switches the target of voltage detection and monitoring to the second electrostatic capacitor 92, and detects and monitors the voltage of the second electrostatic capacitor 92.

[0103] Next, the control unit 7a controls the DC / DC converter 4 so that the voltage of the second electrostatic capacitor 92 of the DC / DC converter 4 is higher than the voltage of the second DC power supply 3. Specifically, the control unit 7a instructs the DC / DC converter 4 to perform a voltage step-down operation, and the DC / DC converter 4 steps down the voltage of the first DC power supply 2 so that the voltage of the second electrostatic capacitor 92 is higher than the voltage of the second DC power supply 3. In this case, by setting the second electrostatic capacitor 92 as the target of power conversion, the voltage of the second electrostatic capacitor 92 can be controlled to any voltage greater than zero using the existing DC / DC converter 4.

[0104] Next, the diagnostic unit 8 measures the potential difference between the two ends of the second switch 6b. If the potential difference between the two ends of the second switch 6b measured by the diagnostic unit 8 is less than a reference value, it can be confirmed that the second switch 6b is unable to disconnect the second DC power supply 3 from the DC / DC converter 4 while failing to properly respond to the instruction from the control unit 7a. Alternatively, if the potential difference between the two ends of the second switch 6b measured by the diagnostic unit 8 is greater than the reference value, it can be confirmed that the second switch 6b is able to disconnect the second DC power supply 3 from the DC / DC converter 4 while being able to respond to the instruction from the control unit 7a. This makes it possible to determine whether the second switch 6b is able to properly disconnect the second DC power supply 3 from the DC / DC converter 4.

[0105] Here, in Figure 5 In the second switch 6a of the fourth modification shown, since it is composed of a single MOSFET, generally speaking, even when the second switch 6a is controlled to the off state, it does not have the capability to cut off the current flowing from the DC / DC converter 4 to the second DC power supply 3 through the body diode, and therefore only cuts off the current flowing from the second DC power supply 3 to the DC / DC converter 4. In contrast, Figure 6 As shown in the second switch 6b of this variant, when it has the performance of cutting off the current flowing from the DC / DC converter 4 to the second DC power supply 3, the method of this variant can diagnose the cutting performance in the direction from the DC / DC converter 4 to the second DC power supply 3.

[0106] [Specific Configuration of DC / DC Converter 4]

[0107] The internal circuit of the DC / DC converter 4 in the embodiment has, for example, the following specific configuration and operates as described below.

[0108] Figure 7 This is a diagram illustrating a circuit of a DC / DC converter 4c according to a first specific example of the DC / DC converter 4 of the embodiment. The diagram shows the overall configuration of a power supply device 1f including the DC / DC converter 4c.

[0109] The DC / DC converter 4 c includes a first switching element 411 , a second switching element 412 , a reactor 413 , a current sensor 42 , a first electrostatic capacitor 91 , and a second electrostatic capacitor 92 .

[0110] like Figure 7As shown, in the DC / DC converter 4c, the first switching element 411 and the reactor 413 are connected in series at a junction J4c, from the first switch 5 side to the second switch 6 side. Furthermore, one end of the second switching element 412 is connected to the junction J4c between the first switching element 411 and the reactor 413, and the other end is grounded.

[0111] The first switching element 411 and the second switching element 412 are both N-channel MOSFETs and have body diodes. The anodes of the body diodes are connected to the source electrodes of the first switching element 411 and the second switching element 412 , and the cathodes are connected to the drain electrodes.

[0112] Next, the operation of the DC / DC converter 4c will be described.

[0113] In the power supply device 1 f , when charging the second DC power supply 3 from the first DC power supply 2 , the DC / DC converter 4 c performs a voltage step-down operation.

[0114] The first switching element 411 and the second switching element 412 switch under control of the control unit 7, stepping down the DC voltage of the first DC power supply 2 and charging the second DC power supply 3. Specifically, as an example, when the first switching element 411 is turned on and the second switching element 412 is turned off, current flows from the first DC power supply 2 to the second DC power supply 3 via the first switching element 411 and the reactor 413, thereby accumulating energy in the reactor 413. Alternatively, when the first switching element 411 is turned off and the second switching element 412 is turned on, the energy accumulated in the reactor 413 is released, causing current to flow from the ground to the second DC power supply 3 via the second switching element 412 and the reactor 413. This state of energy accumulation in the reactor 413 and the state of current flowing from the ground to the second DC power supply 3 via the second switching element 412 and the reactor 413 are repeated alternately.

[0115] In addition, during the switching operation of the first switching element 411 and the second switching element 412, the control unit 7 determines the on-duty cycle of the drive signal, for example, in the drive signal using pulse width modulation (PWM), based on the feedback of the voltage of the second DC power supply 3 to the control unit 7, and controls the output from the DC / DC converter 4c.

[0116] Furthermore, the control unit 7 may determine the on-duty ratio of the drive signal for the first switching element 411 and the second switching element 412 based on the difference between the current value detected by the current sensor 42 and the target current value.

[0117] Furthermore, in the power supply device 1 f , when charging the first DC power supply 2 from the second DC power supply 3 , the DC / DC converter 4 c performs a voltage step-up operation.

[0118] The first switching element 411 and the second switching element 412 switch under control of the control unit 7, stepping up the DC voltage of the second DC power supply 3 and charging the first DC power supply 2. Specifically, as an example, when the first switching element 411 is off and the second switching element 412 is on, current flows from the second DC power supply 3 to ground via the reactor 413 and the second switching element 412, thereby accumulating energy in the reactor 413. Alternatively, when the first switching element 411 is on and the second switching element 412 is off, the energy accumulated in the reactor 413 is released, causing current to flow from the second DC power supply 3 to the first DC power supply 2 via the reactor 413 and the first switching element 411. This state of energy accumulation in the reactor 413 and the state of current flowing from the second DC power supply 3 to the first DC power supply 2 via the reactor 413 and the first switching element 411 are repeated alternately.

[0119] In addition, during the switching operation of the first switching element 411 and the second switching element 412, the control unit 7 determines the on-duty cycle of the drive signal based on the feedback of the voltage of the first DC power supply 2 to the control unit 7, for example, when a pulse width modulation (PWM) drive signal is used, and controls the output from the DC / DC converter 4c.

[0120] Furthermore, the control unit 7 may determine the on-duty ratio of the drive signal for the first switching element 411 and the second switching element 412 based on the difference between the current value detected by the current sensor 42 and the target current value.

[0121] Figure 8 This is a diagram illustrating a circuit of a DC / DC converter 4d, which is a second specific example of the DC / DC converter 4 according to the embodiment. The diagram shows the overall configuration of a power supply device 1g including the DC / DC converter 4d.

[0122] The DC / DC converter 4d includes a first switching element 411, a second switching element 412, a reactor 413, a third switching element 414, a fourth switching element 415, a current sensor 42, a first electrostatic capacitor 91, and a second electrostatic capacitor 92. The DC / DC converter 4d has a configuration similar to the DC / DC converter 4c of Specific Example 1, with the addition of the third switching element 414 and the fourth switching element 415. The following description focuses on the differences from the DC / DC converter 4c of Specific Example 1.

[0123] like Figure 8As shown, in the DC / DC converter 4d, the first switching element 411, the reactor 413, and the third switching element 414 are connected in series at a junction J4d, in this order, from the first switch 5 side to the second switch 6 side. Furthermore, one end of the fourth switching element 415 is connected to the junction J4d between the third switching element 414 and the reactor 413, and the other end is grounded.

[0124] The third switching element 414 and the fourth switching element 415 are both N-channel MOSFETs and have body diodes. The anodes of the body diodes are connected to the source electrodes of the third switching element 414 and the fourth switching element 415, and the cathodes are connected to the drain electrodes.

[0125] Next, the operation of the DC / DC converter 4d will be described.

[0126] In the power supply device 1 g , when charging the second DC power supply 3 from the first DC power supply 2 , the DC / DC converter 4 d can perform not only a step-down operation but also a step-up operation according to an instruction from the control unit 7 .

[0127] When performing the step-down operation, the same operation as that of the DC / DC converter 4 c in the specific example 1 is performed while the third switching element 414 is kept on and the fourth switching element 415 is kept off.

[0128] On the other hand, when performing a boost operation, while the first switching element 411 remains on and the second switching element 412 remains off, the third switching element 414 and the fourth switching element 415 perform switching operations under the control of the control unit 7, thereby boosting the DC voltage of the first DC power supply 2 and charging the second DC power supply 3. Specifically, as an example, while the first switching element 411 remains on and the second switching element 412 remains off, the third switching element 414 is turned off and the fourth switching element 415 is turned on, causing current to flow from the first DC power supply 2 to the ground via the first switching element 411, the reactor 413, and the fourth switching element 415, thereby accumulating energy in the reactor 413. Furthermore, while first switching element 411 remains on and second switching element 412 remains off, third switching element 414 is turned on and fourth switching element 415 is turned off. Energy stored in reactor 413 is released, causing current to flow from first DC power supply 2 to second DC power supply 3 via first switching element 411, reactor 413, and third switching element 414. This state of energy storage in reactor 413 and this state of current flowing from first DC power supply 2 to second DC power supply 3 via first switching element 411, reactor 413, and third switching element 414 are repeated alternately.

[0129] According to the power supply device 1g of the second specific example, as in the embodiment, when the disconnection performance of the first switch 5 is to be diagnosed, after the control unit 7 issues a disconnection instruction to the first switch 5 and a connection instruction to the second switch 6, the DC / DC converter 4d performs a voltage conversion operation to discharge the charge in the first electrostatic capacitor 91 to the second DC power supply 3. Therefore, it is possible to provide a power supply device 1 that can diagnose the disconnection performance of the first switch 5 in a short period of time.

[0130] In addition, during the switching operation of the third switching element 414 and the fourth switching element 415, the control unit 7 determines the on-duty cycle of the drive signal, for example, in a drive signal using pulse width modulation (PWM), based on the feedback of the voltage of the second DC power supply 3 to the control unit 7, and controls the output from the DC / DC converter 4d.

[0131] Furthermore, the control unit 7 may determine the on-duty ratio of the drive signal to the third switching element 414 and the fourth switching element 415 based on the difference between the current value detected by the current sensor 42 and the target current value.

[0132] Furthermore, in the power supply device 1g, when charging the first DC power supply 2 from the second DC power supply 3, the DC / DC converter 4d can perform not only a step-up operation but also a step-down operation according to an instruction from the control unit 7.

[0133] When performing the boost operation, the same operation as that of the DC / DC converter 4 c in the specific example 1 is performed while the third switching element 414 is kept on and the fourth switching element 415 is kept off.

[0134] On the other hand, when performing a voltage step-down operation, while the first switching element 411 remains on and the second switching element 412 remains off, the third switching element 414 and the fourth switching element 415 perform switching operations under the control of the control unit 7, thereby stepping down the DC voltage of the second DC power supply 3 and charging the first DC power supply 2. Specifically, as an example, while the first switching element 411 remains on and the second switching element 412 remains off, the third switching element 414 is turned on and the fourth switching element 415 is turned off, causing current to flow from the second DC power supply 3 to the first DC power supply 2 via the third switching element 414, the reactor 413, and the first switching element 411, thereby accumulating energy in the reactor 413. Furthermore, while first switching element 411 remains on and second switching element 412 remains off, third switching element 414 is off and fourth switching element 415 is on. Energy stored in reactor 413 is released, causing current to flow from ground to first DC power supply 2 via fourth switching element 415, reactor 413, and first switching element 411. This state of energy storage in reactor 413 and this state of current flowing from ground to first DC power supply 2 via fourth switching element 415, reactor 413, and first switching element 411 are repeated alternately.

[0135] According to the power supply device 1g of the second specific example, similar to the embodiment, when the disconnection performance of the second switch 6 is to be diagnosed, after the control unit 7 issues a disconnection instruction to the second switch 6 and a connection instruction to the first switch 5, the DC / DC converter 4d performs a voltage conversion operation to discharge the charge of the second electrostatic capacitor 92 to the first DC power supply 2. Therefore, it is possible to provide a power supply device 1 that can diagnose the disconnection performance of the second switch 6 in a short period of time.

[0136] In addition, during the switching operation of the third switching element 414 and the fourth switching element 415, the control unit 7 determines the on-duty cycle of the drive signal, for example, in a drive signal using pulse width modulation (PWM), based on the feedback of the voltage of the first DC power supply 2 to the control unit 7, and controls the output from the DC / DC converter 4d.

[0137] Furthermore, the control unit 7 may determine the on-duty ratio of the drive signal to the third switching element 414 and the fourth switching element 415 based on the difference between the current value detected by the current sensor 42 and the target current value.

[0138] Figure 9 This is a diagram illustrating a circuit of a DC / DC converter 4e according to Specific Example 3 of the embodiment. The diagram shows the overall configuration of a power supply device 1h including the DC / DC converter 4e.

[0139] The DC / DC converter 4 e includes a fifth switching element 416 , a transformer 417 , a diode 418 , a current sensor 42 , a first electrostatic capacitor 91 , and a second electrostatic capacitor 92 .

[0140] like Figure 9 As shown, in the DC / DC converter 4e, the primary winding of the transformer 417 and the fifth switching element 416 are connected in series from the first switch 5 side. The fifth switching element 416 is an N-channel MOSFET with a source electrode grounded and a drain electrode connected to the primary winding of the transformer 417, and has a body diode. The anode of the body diode is connected to the source electrode side of the fifth switching element 416, and the cathode is connected to the drain electrode side.

[0141] One end of the secondary winding of the transformer 417 is grounded, and the other end is connected to the anode of the diode 418. The cathode of the diode 418 is connected to the second switch 6.

[0142] Next, the operation of the DC / DC converter 4e will be described.

[0143] The DC / DC converter 4e charges the second DC power supply 3 from the first DC power supply 2. In the power supply device 1h, when charging the second DC power supply 3 from the first DC power supply 2, the DC / DC converter 4e performs a step-up or step-down operation in accordance with instructions from the control unit 7. Whether the step-up or step-down operation is performed is determined by, for example, the winding ratio of the transformer 417 and the on-duty ratio of the control signal from the control unit 7 to the fifth switching element 416.

[0144] During charging from the first DC power supply 2 to the second DC power supply 3, the fifth switching element 416 performs a switching operation under the control of the control unit 7, thereby stepping up or down the DC voltage of the first DC power supply 2 to charge the second DC power supply 3. Specifically, as an example, the switching of the fifth switching element 416 causes current to intermittently flow through the primary winding of the transformer 417, thereby generating an AC voltage in the secondary winding of the transformer 417. This AC voltage is half-wave rectified by the diode 418, smoothed by the second electrostatic capacitor 92, and converted into a DC voltage, which is then output to the second DC power supply 3.

[0145] According to the power supply device 1h of Specific Example 3, similar to the embodiment, when the disconnection performance of the first switch 5 is to be diagnosed, after the control unit 7 issues a disconnection instruction to the first switch 5 and a connection instruction to the second switch 6, the DC / DC converter 4e performs a voltage conversion operation to discharge the charge in the first electrostatic capacitor 91 to the second DC power supply 3. Therefore, it is possible to provide a power supply device 1 that can diagnose the disconnection performance of the first switch 5 in a short period of time.

[0146] In addition, during the switching operation of the fifth switching element 416, the control unit 7 determines the on-duty cycle based on the feedback of the voltage of the second DC power supply 3 to the control unit 7, for example, in a drive signal using pulse width modulation (PWM), and controls the output from the DC / DC converter 4e.

[0147] Furthermore, the control unit 7 may determine the on-duty ratio of the drive signal to the fifth switching element 416 based on the difference between the current value detected by the current sensor 42 and the target current value.

[0148] As described above, the power supply device 1 according to the present embodiment, its variations, and its specific examples is a power supply device connected between a first DC power supply 2 that supplies and maintains a first voltage and a second DC power supply 3 that supplies and maintains a second voltage, and includes: a first switch 5 having one end connected to the first DC power supply 2; a DC / DC converter 4 having a first electrostatic capacitor 91 connected to the other end of the first switch 5, and performing at least one of a first operation and a second operation, wherein the first operation converts the voltage stored in the first electrostatic capacitor 91 into the second voltage and outputs the converted second voltage to the second DC power supply 3; and a second operation converts the second voltage supplied and maintained by the second DC power supply 3 into a third voltage and outputs the converted third voltage to the first electrostatic capacitor 91; and a control unit 7 that controls the DC / DC converter 4 and the first switch 5, detects a potential difference across the first switch 5, instructs the first switch 5 to be disconnected, detects the potential difference after the DC / DC converter 4 performs the first operation or the second operation, and determines that the first switch 5 is normal when the detected potential difference is greater than a first reference potential difference.

[0149] Thus, during the diagnosis of first switch 5, DC / DC converter 4 performs the first or second operation after first switch 5 is disconnected. Therefore, if the disconnection capability of first switch 5 is normal, the potential difference between both ends of first switch 5 increases in a shorter time than before. This enables a power supply device capable of quickly diagnosing the disconnection performance of a switch provided between the input or output side and the DC / DC converter included in the power supply device.

[0150] Here, as the first operation or the second operation, the DC / DC converter 4 can perform a step-down operation or a step-up operation. Thus, a power supply device that converts power between the first DC power supply 2 and the second DC power supply 3 having various voltages can be realized.

[0151] Furthermore, the DC / DC converter 4 may include a current sensor 42 for detecting a current flowing through the DC / DC converter 4 . Thus, the DC / DC converter 4 can perform at least one of the first operation and the second operation by control based on the current detected by the current sensor 42 .

[0152] For example, when the current detected by the current sensor 42 is equal to or greater than a predetermined value, the DC / DC converter 4 can be determined to be abnormal and stop at least one of the first operation and the second operation.

[0153] Furthermore, the DC / DC converter 4 can charge the first electrostatic capacitor 91 to an arbitrary third voltage through the first operation or the second operation when the first switch 5 is disconnected. This prevents the potential difference between the two ends of the first switch 5 from becoming excessively large during diagnosis of the first switch 5, and shortens the time required for the voltage of the first electrostatic capacitor 91 to recover upon completion of diagnosis.

[0154] Alternatively, after disconnecting the first switch 5, the control unit 7 may cause the DC / DC converter 4 to perform a first operation, thereby reducing the voltage of the first electrostatic capacitor 91 to less than the first voltage. This allows diagnosis of the first switch 5 to be performed in a shorter time than conventional methods, and also allows diagnosis of the first switch 5's ability to disconnect current flowing from the terminal connected to the first DC power supply 2 to the terminal connected to the first electrostatic capacitor 91.

[0155] Alternatively, after disconnecting the first switch 5, the control unit 7 may cause the DC / DC converter 4 to perform a second operation, thereby increasing the voltage of the first electrostatic capacitor 91 to be greater than the first voltage. This allows the diagnosis of the first switch 5 to be performed in a shorter time than conventional methods, and also allows the diagnosis of the first switch 5's disconnect capability against current flowing from the terminal connected to the first electrostatic capacitor 91 to the terminal connected to the first DC power supply 2.

[0156] In addition, the power supply device 1 may further include a second switch 6 having one end connected to the second DC power supply 3, the DC / DC converter 4 may further include a second electrostatic capacitor 92 connected to the other end of the second switch 6, the control unit 7 may further disconnect the second switch 6, and after causing the DC / DC converter 4 to perform the first action or the second action, detect the potential difference between the two ends of the second switch 6, and when the detected potential difference is greater than the second reference potential difference, determine that the second switch 6 is normal.

[0157] Thus, not only the first switch 5 can be diagnosed, but also the second switch 6 can be diagnosed in the same manner as the first switch 5 .

[0158] Furthermore, the switch diagnostic method according to the present embodiment, modified example, and specific example is a method for diagnosing a first switch 5 included in a power supply device 1, which is connected between a first DC power supply 2 that supplies and maintains a first voltage and a second DC power supply 3 that supplies and maintains a second voltage. One end of the first switch 5 is connected to the first DC power supply 2. The power supply device 1 includes a DC / DC converter 4 having a first electrostatic capacitor 91 connected to the other end of the first switch 5. The DC / DC converter 4 performs at least one of a first operation and a second operation. The first operation converts a voltage stored in the first electrostatic capacitor 91 into a second voltage and outputs the converted second voltage to the second DC power supply 3. The second operation converts the second voltage supplied and maintained by the second DC power supply 3 into a third voltage and outputs the converted third voltage to the first electrostatic capacitor 91. The diagnostic method disconnects both ends of the first switch 5 (S10). After the DC / DC converter 4 performs the first operation or the second operation (S12), the potential difference between both ends of the first switch 5 is detected (S13). If the detected potential difference is greater than a first reference potential difference (No in S14), the first switch 5 is determined to be normal (S16).

[0159] Thus, during the diagnosis of first switch 5, DC / DC converter 4 performs the first or second operation after first switch 5 is disconnected. Therefore, if the disconnection capability of first switch 5 is normal, the potential difference between both ends of first switch 5 increases in a shorter time than before. This provides a switch diagnosis method that can quickly diagnose the disconnection performance of a switch provided between the input or output side and a DC / DC converter included in a power supply device.

[0160] While the power supply device and switch diagnostic method of the present disclosure have been described above based on the embodiments, variations, and specific examples, the present disclosure is not limited to these embodiments, variations, and specific examples. As long as they do not depart from the spirit of the present disclosure, other methods constructed by implementing various variations of the embodiments, variations, and specific examples that occur to those skilled in the art, or by combining some of the components of the embodiments, variations, and specific examples, are also within the scope of the present disclosure.

[0161] Industrial applicability

[0162] The power supply device disclosed herein is a power supply device that is connected between two DC power supplies to perform voltage conversion. More specifically, it is a power supply device that can diagnose the disconnection performance of a switch provided between the input side or the output side and a DC / DC converter provided in the power supply device in a short period of time. For example, it can be widely used in a vehicle-mounted power conversion device that performs power conversion between a battery and a capacitor.

[0163] Description of Reference Numerals

[0164] 1. 1a~1h power supply device

[0165] 2. First DC power supply

[0166] 3 Second DC power supply

[0167] 4. 4a~4e DC / DC converters

[0168] 41 Power conversion circuit

[0169] 411 first switching element

[0170] 412 second switching element

[0171] 413 reactor

[0172] 414 third switching element

[0173] 415 fourth switching element

[0174] 416 fifth switching element

[0175] 417 Transformer

[0176] 418 diode

[0177] 42 current sensor

[0178] 5, 5a, 5b first switch

[0179] 51 first voltage detection unit

[0180] 52 second voltage detection unit

[0181] 53 fifth voltage detection unit

[0182] 6, 6a, 6b second switch

[0183] 61 third voltage detection unit

[0184] 62 fourth voltage detection unit

[0185] 63 Sixth voltage detection unit

[0186] 7.7a Control unit

[0187] 8Diagnosis Department

[0188] 91 first electrostatic capacitor

[0189] 92 second electrostatic capacitance

[0190] 100 vehicles

Claims

1. A power supply device, configured to be connected between a first DC power supply that supplies and maintains a first voltage and a second DC power supply that supplies and maintains a second voltage, the power supply device comprising: A first switch, one end of which is connected to the first DC power supply; A DC / DC converter having a first electrostatic capacitor connected to the other end of the first switch; and a control unit configured to control the DC / DC converter and the first switch and detect a potential difference between the one end and the other end of the first switch, The DC / DC converter is configured to perform at least one of a first operation and a second operation. The first action converts the voltage stored in the first electrostatic capacitor into the second voltage, and outputs the converted second voltage to the second DC power supply. The second action converts the second voltage supplied and maintained by the second DC power supply into a third voltage, and outputs the converted third voltage to the first electrostatic capacitor. The control unit is configured as follows: After instructing to turn off the first switch and causing the DC / DC converter to perform the first operation or the second operation, the potential difference is detected; When the detected potential difference is larger than a first reference potential difference, it is determined that the first switch is normal.

2. The power supply device according to claim 1, wherein: The control unit is configured to determine that the first switch is abnormal when the detected potential difference is not greater than the first reference potential difference.

3. The power supply device according to claim 1 or 2, wherein: The DC / DC converter is configured to perform a voltage step-down operation as the first operation or the second operation.

4. The power supply device according to claim 1 or 2, wherein: The DC / DC converter is configured to perform a voltage step-up operation as the first operation or the second operation.

5. The power supply device according to any one of claims 1 to 4, wherein: The DC / DC converter includes a current sensor configured to detect a current flowing through the DC / DC converter.

6. The power supply device according to claim 5, wherein: The DC / DC converter is configured to perform at least one of the first operation and the second operation through control based on the current detected by the current sensor.

7. The power supply device according to claim 6, wherein: The DC / DC converter is configured to stop at least one of the first operation and the second operation when the current detected by the current sensor is equal to or greater than a predetermined value.

8. The power supply device according to any one of claims 1 to 7, wherein: The DC / DC converter is configured to charge the first electrostatic capacitor to any of the third voltages through the first operation or the second operation when the first switch is turned off.

9. The power supply device according to any one of claims 1 to 8, wherein: The control unit is configured to, after instructing to turn off the first switch, cause the DC / DC converter to perform the first operation, thereby reducing the voltage of the first electrostatic capacitor so that the voltage of the first electrostatic capacitor becomes lower than the first voltage.

10. The power supply device according to any one of claims 1 to 8, wherein: The control unit is configured to, after instructing to turn off the first switch, cause the DC / DC converter to perform the second operation to increase the voltage of the first electrostatic capacitor so that the voltage of the first electrostatic capacitor becomes larger than the first voltage.

11. The power supply device according to any one of claims 1 to 10, wherein: The power supply device further includes a second switch, one end of which is connected to the second DC power supply. The DC / DC converter further includes a second electrostatic capacitor connected to the other end of the second switch. The control unit is configured as follows: After instructing to turn off the second switch and to cause the DC / DC converter to perform the first operation or the second operation, detecting a potential difference between both ends of the second switch, When the detected potential difference is larger than a second reference potential difference, it is determined that the second switch is normal.

12. A diagnostic method for a power supply device connected between a first DC power supply that supplies and maintains a first voltage and a second DC power supply that supplies and maintains a second voltage, the diagnostic method comprising the following steps: Steps of preparing a power supply device, the power supply device comprising: a switch, one end of which is connected to the first DC power supply; and A DC / DC converter has a first electrostatic capacitor connected to the other end of the switch, and the DC / DC converter is configured to perform at least one of a first operation and a second operation. The first action converts the voltage stored in the first electrostatic capacitor into the second voltage, and outputs the converted second voltage to the second DC power supply. The second action converts the second voltage supplied and maintained by the second DC power supply into a third voltage, and outputs the converted third voltage to the first electrostatic capacitor; After instructing to turn off the switch and causing the DC / DC converter to perform the first action or the second action, detecting a potential difference between the first end and the other end of the switch; as well as A step of determining that the switch is normal when the detected potential difference is larger than a reference potential difference.

13. The diagnostic method according to claim 12, wherein: The diagnostic method further includes a step of determining that the first switch is abnormal when the detected potential difference is not greater than the reference potential difference.

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