Power supply switching circuit

Abstract

To provide a power supply switching circuit capable of maintaining the operation of a circuit without any malfunction.SOLUTION: A power supply switching circuit 101 is connected to a first power source 210 and a second power source 220, and is also connected to a first circuit 310 and a second circuit 320. The power supply switching circuit includes a first main path 1m, a second main path 2m, a first switching path 3, and a second switching path 4. The power supply switching circuit also includes a control circuit 20 that forms a power supply path by controlling each of the first main path, the second main path, the first switching path, and the second switching path to either a conductive state or a non-conductive state. When a malfunction occurs in one of the first and second circuits, the control circuit forms a power supply path that does not affect the operation of the other circuit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power supply switching circuit.

Background Art

[0002] As an example of a power supply switching circuit, there is a multiple battery switching circuit disclosed in Patent Document 1. The multiple battery switching circuit selectively interconnects any one of a plurality of batteries with a load or a charger.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a power supply switching circuit may be configured to include a first path for supplying power from a first power source to a first circuit, a second path for supplying power from a second power source to a second circuit, a third path for supplying power from the first power source to the second circuit, and a fourth path for supplying power from the second power source to the first circuit. In such a configuration, when supplying power to the second circuit while the first circuit has a short-circuit fault, there is a risk that a short-circuit current will flow from both the first power source and the second power source to the first circuit. Therefore, the power supply switching circuit has a problem that it cannot supply power to the second circuit and cannot maintain the operation of the second circuit. From the above viewpoints, or from other viewpoints not mentioned, further improvement of the power supply switching circuit is required.

[0005] One object of the disclosure is to provide a power supply switching circuit that can maintain the operation of a circuit without problems.

Means for Solving the Problems

[0006] The power supply switching circuit disclosed herein is A power supply switching circuit connected to a first power supply (210) and a second power supply (220) and also connected to a first circuit (310) and a second circuit (320), A first main path (1m) for supplying power from the first power supply to the first circuit, A second main path (2m) for supplying power from the second power supply to the second circuit, A first switching path (3) for switching the power supply source to the first circuit from the first power supply to the second power supply when the first power supply is abnormal, A second switching path (4) for switching the power supply source to the second circuit from the second power supply to the first power supply when the second power supply is abnormal, A control circuit (20) for forming a power supply path by controlling each of the first main path, the second main path, the first switching path, and the second switching path to be in either a conductive state or a non-conductive state, The control circuit is characterized in that when a malfunction occurs in one of the first circuit and the second circuit, it forms a power supply path that does not affect the operation of the other circuit.

[0007] According to the power supply switching circuit disclosed herein, when a malfunction occurs in one of the first circuit and the second circuit, it forms a power supply path that does not affect the operation of the other circuit. Therefore, the power supply switching circuit can maintain the operation of the non-malfunctioning one of the first circuit and the second circuit.

[0008] The plurality of aspects disclosed in this specification adopt different technical means to achieve their respective purposes. The reference numerals in parentheses described in the claims and this section are exemplarily shown for the correspondence with parts of the embodiments described later, and are not intended to limit the technical scope. The purposes, features, and effects disclosed in this specification will become clearer by referring to the subsequent detailed description and the accompanying drawings.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, with reference to the drawings, a plurality of embodiments for implementing the present disclosure will be described. In each embodiment, parts corresponding to those described in the preceding embodiments may be denoted by the same reference numerals, and redundant descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other parts of the configuration may be referred to and applied to other embodiments described previously.

[0011] (First Embodiment) With reference to FIGS. 1 to 10, the power supply switching circuit 101 of the first embodiment will be described. The power supply switching circuit 101 is configured to be mountable on, for example, a moving body. Examples of the moving body include vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles, flying bodies such as electric vertical takeoff and landing aircraft and drones, ships, construction machines, and agricultural machines.

[0012] The power supply switching circuit 101 is connected to a first power supply 210 and a second power supply 220. Also, the power supply switching circuit 101 is connected to a first circuit 310 and a second circuit 320. The power supply switching circuit 101 provides a power supply path for supplying power from the first power supply 210 to the first circuit 310. Also, the power supply switching circuit 101 provides a power supply path for supplying power from the second power supply 220 to the second circuit 320. In the drawings, the first power supply 210 is denoted as PS1, the second power supply 220 is denoted as PS2, the first circuit 310 is denoted as CKT1, and the second circuit 320 is denoted as CKT2.

[0013] Furthermore, the power supply switching circuit 101 switches the power supply paths for the first circuit 310 and the second circuit 320. That is, the power supply switching circuit 101 switches the power supply for the first circuit 310 from the first power supply 210 to the second power supply 220, or switches the power supply for the second circuit 320 from the second power supply 220 to the first power supply 210. Thus, the power supply switching circuit 101 has a switching function. Also, it can be said that the power supply switching circuit 101 performs power supply switching.

[0014] The first power supply 210 and the second power supply 220 can employ rechargeable secondary batteries or non-rechargeable primary batteries. The first power supply 210 and the second power supply 220 can both be secondary batteries or primary batteries, or one can be a secondary battery and the other can be a primary battery. A rechargeable secondary battery can also be said to be a power supply with charging permission. On the other hand, a non-rechargeable primary battery can also be said to be a power supply with charging prohibition.

[0015] Loads are connected to the first circuit 310 and the second circuit 320. The first circuit 310 and the second circuit 320 are electronic control devices that control the loads.

[0016] <Configuration> The configuration of the power supply switching circuit 101 will be described with reference to FIGS. 1, 2, and 3. The power supply switching circuit 101 includes a plurality of MOSFETs 11 to 18, a control circuit 20, a wiring board 30, capacitors 61, 62, etc. In the drawings, each of the MOSFETs 11 to 18 is denoted as SW1 to SW8.

[0017] The plurality of MOSFETs 11 to 18 are mounted on the wiring board 30, which will be described later. The plurality of MOSFETs 11 to 18 are connected to the wirings provided on the wiring board 30. The plurality of MOSFETs 11 to 18 include body diodes.

[0018] The drain electrodes of the first MOSFET 11 and the second MOSFET 12 are connected to each other. Also, the cathodes of the body diodes of the first MOSFET 11 and the second MOSFET 12 are connected to each other.

[0019] The drain electrodes of the third MOSFET 13 and the fourth MOSFET 14 are connected to each other. Also, the cathodes of the body diodes of the third MOSFET 13 and the fourth MOSFET 14 are connected to each other.

[0020] The drain electrodes of the fifth MOSFET 15 and the sixth MOSFET 16 are connected to each other. Also, the cathodes of the body diodes of the fifth MOSFET 15 and the sixth MOSFET 16 are connected to each other.

[0021] The drain electrodes of the seventh MOSFET 17 and the eighth MOSFET 18 are connected to each other. Also, the cathodes of the body diodes of the seventh MOSFET 17 and the eighth MOSFET 18 are connected to each other.

[0022] In this embodiment, NchMOSFETs are adopted as the MOSFETs 11 to 18. However, the present disclosure can also adopt PchMOSFETs. In this case, the source electrodes of the corresponding two MOSFETs are connected to each other. The corresponding two MOSFETs are, for example, the first MOSFET 11 and the second MOSFET 12, the third MOSFET 13 and the fourth MOSFET 14, and the like.

[0023] As shown in FIGS. 3 and 4, the wiring substrate 30 has conductive wirings formed on an insulating substrate. The wiring substrate 30 has a plurality of MOSFETs 11 to 18 mounted thereon. The wirings include a first main wiring 31m, a first sub-wiring 31s, a second main wiring 32m, a second sub-wiring 32s, a switching wiring 33, a gate wiring 40, and the like. Note that in FIGS. 3 and 4, the illustration of the gate wiring 40 is omitted.

[0024] At least the first main wiring 31m, the first sub-wiring 31s, the second main wiring 32m, the second sub-wiring 32s, and the switching wiring 33, which are power supply wirings, can be provided without intersecting three-dimensionally. Also, it can be said that each power supply wiring can be provided without crossing each other's wirings. Therefore, the power supply wirings can be formed on the same surface of the insulating substrate. That is, the power supply wirings are formed without passing through vias (interlayer connection members). Also, it can be said that the first main path 1m, the second main path 2m, the first switching path 3, and the second switching path 4, which will be described later, are formed on the same plane of the wiring substrate 30. In this embodiment, as an example, a configuration in which a power supply line is provided on the surface layer of the insulating substrate is adopted.

[0025] Therefore, the power supply switching circuit 101 can simplify the routing of the gate wiring 40. In this embodiment, a wiring substrate 30 provided with a gate wiring 40 as an example of a signal wiring is adopted. However, in addition to the gate wiring 40, other signal wirings may be provided on the wiring substrate 30. In such a configuration, the power supply switching circuit 101 can also simplify the routing of signal wirings other than the gate wiring 40. Furthermore, the arrangement of the circuit components constituting the power supply switching circuit 101 can be simplified, and the substrate area can be effectively utilized.

[0026] Furthermore, since the power supply wiring of the power supply switching circuit 101 is provided on the surface layer, the power supply switching circuit 101 can suppress the temperature rise of the wiring substrate 30 more than a configuration in which the power supply wiring is provided on the inner layer. Also, the power supply switching circuit 101 can arrange a plurality of MOSFETs 11 to 18 on the same surface of the wiring substrate 30. Therefore, even when heat dissipation of the MOSFETs 11 to 18 is required, the power supply switching circuit 101 can simplify the heat dissipation structure.

[0027] The first MOSFET 11 and the second MOSFET 12 are connected to the first main wiring 31m. The first main wiring 31m connects between the drain electrodes of the first MOSFET 11 and the second MOSFET 12. The first main wiring 31m is connected to the source electrode of the first MOSFET 11 and the source electrode of the second MOSFET 12. The source electrode of the first MOSFET 11 is connected to the first power supply 210 via the first main wiring 31m. The source electrode of the second MOSFET 12 is connected to the first circuit 310 via the first main wiring 31m.

[0028] The first main path 1m includes the first MOSFET 11, the second MOSFET 12, and the first main wiring 31m. One end of the first main path 1m is connected to the first power supply 210, and the other end is connected to the first circuit 310. The first main path 1m is a path for supplying power from the first power supply 210 to the first circuit 310. That is, when the first MOSFET 11 and the second MOSFET 12 are turned on, the first main path 1m becomes a power supply path from the first power supply 210 to the first circuit 310. The first main path 1m corresponds to the first main path. Note that the first MOSFET 11 and the second MOSFET 12 connected by the first main wiring 31m can also be said to be the first main switch section.

[0029] The third MOSFET 13 and the fourth MOSFET 14 are connected to the first sub-wiring 31s. The first sub-wiring 31s connects between the drain electrodes of the third MOSFET 13 and the fourth MOSFET 14. The first sub-wiring 31s is connected to the source electrode of the third MOSFET 13 and the source electrode of the fourth MOSFET 14. The source electrode of the third MOSFET 13 is connected to the first power supply 210 via the first sub-wiring 31s. The source electrode of the fourth MOSFET 14 is connected to the first circuit 310 via the first sub-wiring 31s.

[0030] The first sub-path 1s includes the third MOSFET 13, the fourth MOSFET 14, and the first sub-wiring 31s. The first sub-path 1s is provided redundantly with respect to the first main path 1m. The first sub-path 1s can be used as a power supply path instead of the first main path 1m when the third MOSFET 13 and the fourth MOSFET 14 are turned on. The first sub-path 1s can also be said to be the first sub-path.

[0031] The seventh MOSFET 17 and the eighth MOSFET 18 are connected to the second main wiring 32m. The second main wiring 32m connects between the drain electrodes of the seventh MOSFET 17 and the eighth MOSFET 18. The second main wiring 32m is also connected to the source electrode of the seventh MOSFET 17 and the source electrode of the eighth MOSFET 18. The source electrode of the seventh MOSFET 17 is connected to the second power supply 220 via the second main wiring 32m. The source electrode of the eighth MOSFET 18 is connected to the second circuit 320 via the second main wiring 32m.

[0032] The second main path 2m includes the seventh MOSFET 17, the eighth MOSFET 18, and the second main wiring 32m. One end of the second main path 2m is connected to the second power supply 220, and the other end is connected to the second circuit 320. The second main path 2m is a path for supplying power from the second power supply 220 to the second circuit 320. That is, the second main path 2m becomes a power supply path from the second power supply 220 to the second circuit 320 when the seventh MOSFET 17 and the eighth MOSFET 18 are turned on. The second main path 2m corresponds to the second main path. Note that the seventh MOSFET 17 and the eighth MOSFET 18 connected by the second main wiring 32m can also be said to be the second main switch section.

[0033] The fifth MOSFET 15 and the sixth MOSFET 16 are connected to the second sub-wiring 32s. The second sub-wiring 32s connects between the drain electrodes of the fifth MOSFET 15 and the sixth MOSFET 16. The second sub-wiring 32s is connected to the source electrode of the fifth MOSFET 15 and the source electrode of the sixth MOSFET 16. The source electrode of the fifth MOSFET 15 is connected to the second power supply 220 via the second sub-wiring 32s. The source electrode of the sixth MOSFET 16 is connected to the second circuit 320 via the second sub-wiring 32s.

[0034] The second sub-path 2s includes the fifth MOSFET 15, the sixth MOSFET 16, and the second sub-wiring 32s. The second sub-path 2s is provided redundantly with respect to the second main path 2m. The second sub-path 2s can be used as a power supply path instead of the second main path 2m when the fifth MOSFET 15 and the sixth MOSFET 16 are turned on. The second sub-path 2s can also be said to be the second sub-path.

[0035] Furthermore, a switching wiring 33 is connected to the first sub-wiring 31s that connects between the drain electrodes of the third MOSFET 13 and the fourth MOSFET 14. Also, a switching wiring 33 is connected to the second sub-wiring 32s that connects between the drain electrodes of the fifth MOSFET 15 and the sixth MOSFET 16. In this way, the switching wiring 33 connects the first sub-path 1s and the second sub-path 2s.

[0036] The fourth MOSFET 14 and the fifth MOSFET 15 have the cathodes of their body diodes connected to each other via the switching wiring 33. The first switching path 3 includes the fourth MOSFET 14, the fifth MOSFET 15, a part of the second sub-wiring 32s, a part of the first sub-wiring 31s, and the switching wiring 33. One end of the first switching path 3 is connected to the second power supply 220, and the other end is connected to the first circuit 310. The first switching path 3 is a path for switching the power supply source to the first circuit 310 from the first power supply 210 to the second power supply 220 when the first power supply 210 is abnormal. That is, the power supply path for the first circuit 310 is configured to be switchable from the first main path 1m to the first switching path 3.

[0037] The third MOSFET 13 and the sixth MOSFET 16 have the cathodes of their body diodes connected to each other via the switching wiring 33. The second switching path 4 includes the third MOSFET 13, the sixth MOSFET 16, a part of the first sub-wiring 31s, a part of the second sub-wiring 32s, and the switching wiring 33. One end of the second switching path 4 is connected to the first power supply 210, and the other end is connected to the second circuit 320. The second switching path 4 is a path for switching the power supply source to the second circuit 320 from the second power supply 220 to the first power supply 210 when the second power supply 220 is abnormal. That is, the power supply path for the second circuit 320 is configured to be switchable from the second main path 2m to the second switching path 4.

[0038] Note that the first main wiring 31m connecting the first switching path 3 and the first circuit 310 has the first capacitor 61 connected thereto. One end of the first capacitor 61 is connected to the first main wiring 31m, and the other end is connected to the ground. Similarly, the second main wiring 32m connecting the second switching path 4 and the second circuit 320 has the second capacitor 62 connected thereto. One end of the second capacitor 62 is connected to the second main wiring 32m, and the other end is connected to the ground. Thereby, the power supply switching circuit 101 can reduce voltage fluctuations when switching the power supply path. However, the power supply switching circuit 101 may not be provided with the capacitors 61 and 62.

[0039] As shown in FIG. 1, the control circuit 20 is connected to a first main path 1m, a second main path 2m, a first switching path 3, and a second switching path 4. The control circuit 20 forms a power supply path by controlling each of the first main path 1m, the second main path 2m, the first switching path 3, and the second switching path 4 to be either in a conductive state or a non-conductive state (on or off). Further, the control circuit 20 forms a power supply path by controlling each of the first sub-path 1s and the second sub-path 2s to be either in a conductive state or a non-conductive state. Note that the control circuit 20 controls each path to be either in a conductive state or a non-conductive state by performing on / off control of a plurality of MOSFETs 11 to 18.

[0040] Furthermore, when a defect occurs in one of the first circuit 310 and the second circuit 320, the control circuit 20 forms a power supply path that does not affect the operation of the other circuit. Also, when a defect occurs in the first main path 1m or the second main path 2m, the control circuit 20 forms a power supply path so that power is supplied to the first circuit 310 and the second circuit 320. These points will be described in detail later.

[0041] The control circuit 20 includes a first control circuit section 21, a second control circuit section 22, a third control circuit section 23, and a fourth control circuit section 24. Each control circuit section 21 to 24 is individually supplied with operating power. Each control circuit section 21 to 24 may be configured to be able to communicate with each other. In the drawings, the control circuit section is denoted as CC.

[0042] The first control circuit section 21 is supplied with operating power from a first operating power source 51. The first control circuit section 21 is connected to the gate electrodes of the first MOSFET 11 and the second MOSFET 12 via a gate wiring 40. The first control circuit section 21 performs on / off control of the first MOSFET 11 and the second MOSFET 12. The first MOSFET 11 and the second MOSFET 12 correspond to a first semiconductor switching element. The first control circuit section 21 corresponds to a first control section. Hereinafter, the first MOSFET 11 and the second MOSFET 12 are also collectively referred to as a first switch section.

[0043] The second control circuit section 22 is supplied with operating power from the second operating power source 52. The second control circuit section 22 is connected to the gate electrodes of the fourth MOSFET 14 and the fifth MOSFET 15 via the gate wiring 40. The second control circuit section 22 controls the on / off states of the fourth MOSFET 14 and the fifth MOSFET 15. The fourth MOSFET 14 and the fifth MOSFET 15 correspond to the third semiconductor switching element. The second control circuit section 22 corresponds to the third control section. Hereinafter, the fourth MOSFET 14 and the fifth MOSFET 15 are also collectively referred to as the third switch section.

[0044] The third control circuit section 23 is supplied with operating power from the third operating power source 53. The third control circuit section 23 is connected to the gate electrodes of the third MOSFET 13 and the sixth MOSFET 16 via the gate wiring 40. The third control circuit section 23 controls the on / off states of the third MOSFET 13 and the sixth MOSFET 16. The third MOSFET 13 and the sixth MOSFET 16 correspond to the fourth semiconductor switching element. The third control circuit section 23 corresponds to the fourth control section. Hereinafter, the third MOSFET 13 and the sixth MOSFET 16 are also collectively referred to as the fourth switch section.

[0045] The fourth control circuit section 24 is supplied with operating power from the fourth operating power source 54. The fourth control circuit section 24 is connected to the gate electrodes of the seventh MOSFET 17 and the eighth MOSFET 18 via the gate wiring 40. The fourth control circuit section 24 controls the on / off states of the seventh MOSFET 17 and the eighth MOSFET 18. The seventh MOSFET 17 and the eighth MOSFET 18 correspond to the second semiconductor switching element. The fourth control circuit section 24 corresponds to the second control section. Hereinafter, the seventh MOSFET 17 and the eighth MOSFET 18 are also collectively referred to as the second switch section.

[0046] Thus, the power supply switching circuit 101 is provided with control circuit sections 21 to 24 for each switch section. Therefore, the power supply switching circuit 101 can suppress the situation where power supply to each of the circuits 310 and 320 becomes impossible due to a single failure.

[0047] Further, in the power supply switching circuit 101, operating power supplies 51 to 54 are connected to each of the control circuit units 21 to 24. That is, each of the control circuit units 21 to 24 is individually supplied with operating power. Therefore, the power supply switching circuit 101 can suppress the switching function from stopping due to a power failure compared to a configuration in which a common operating power supply is connected to a plurality of control circuit units 21 to 24.

[0048] Each of the control circuit units 21 to 24 may be supplied with operating power from the first power supply 210 and the second power supply 220. In this case, it is preferable that the first control circuit unit 21 and the second control circuit unit 22 have different power supplies. It is preferable that the third control circuit unit 23 and the fourth control circuit unit 24 have different power supplies.

[0049] For example, the first control circuit unit 21 is supplied with operating power from the first power supply 210, the second control circuit unit 22 is supplied with operating power from the second power supply 220, the third control circuit unit 23 is supplied with operating power from the first power supply 210, and the fourth control circuit unit 24 is supplied with operating power from the second power supply 220 (first supply mode). Alternatively, the first power supply 210 and the second power supply 220 may be OR-connected to each of the control circuit units 21 to 24. In this case, each of the control circuit units 21 to 24 will be supplied with operating power from the power supply with the higher voltage between the first power supply 210 and the second power supply 220 (second supply mode). Even with such a configuration, it is possible to suppress the inability to supply power as described above.

[0050] Furthermore, the first control circuit unit 21 may be supplied with operating power from the second power supply 220, the second control circuit unit 22 may be supplied with operating power from the first power supply 210, the third control circuit unit 23 may be supplied with operating power from the second power supply 220, and the fourth control circuit unit 24 may be supplied with operating power from the first power supply 210. However, this mode of supplying operating power is subject to the following constraints.

[0051] When the first power supply 210 is abnormal (voltage drop), in the first circuit 310, the MOSFETs 14 and 15 are turned on and power is supplied from the second power supply 220. When the operating power supply 52 of the second control circuit unit 22 is connected to the first power supply 210, if the voltage of the first power supply 210 is equal to or higher than the voltage at which the second control circuit unit 22 can operate (for example, 3V), the MOSFETs 14 and 15 can be turned on. Therefore, power can be supplied from the second power supply 220 to the first circuit 310.

[0052] However, when the voltage of the first power supply 210 drops below the voltage at which the second control circuit section 22 can operate, the MOSFETs 14 and 15 cannot be turned on. Therefore, power cannot be supplied from the second power supply 220 to the first circuit 310.

[0053] Also, when the first power supply 210 is abnormal, the second circuit 320 has the MOSFETs 17 and 18 turned on and is supplied with power from the second power supply 220. When the operating power supply 54 of the fourth control circuit section 24 is connected to the first power supply 210, when the voltage of the first power supply 210 is equal to or higher than the voltage at which the fourth control circuit section 24 can operate (for example, 3V), the MOSFETs 17 and 18 can be turned on. Therefore, power can be supplied from the second power supply 220 to the second circuit 320.

[0054] However, when the voltage of the first power supply 210 drops below the voltage at which the fourth control circuit section 24 can operate, the MOSFETs 17 and 18 cannot be turned on. Therefore, power cannot be supplied from the second power supply 220 to the second circuit 320.

[0055] On the other hand, when the second power supply 220 is abnormal (voltage drop), the first circuit 310 has the MOSFETs 11 and 12 turned on and is supplied with power from the first power supply 210. When the operating power supply 51 of the first control circuit section 21 is connected to the second power supply 220, when the voltage of the second power supply 220 is equal to or higher than the voltage at which the first control circuit section 21 can operate (for example, 3V), the MOSFETs 11 and 12 can be turned on. Therefore, power can be supplied from the first power supply 210 to the first circuit 310.

[0056] However, when the voltage of the second power supply 220 drops below the voltage at which the first control circuit section 21 can operate, the MOSFETs 11 and 12 cannot be turned on. Therefore, power cannot be supplied from the first power supply 210 to the first circuit 310.

[0057] Also, when the second power supply 220 is abnormal, the second circuit 320 has the MOSFETs 13 and 16 turned on and is powered from the first power supply 210. When the operating power supply 53 of the third control circuit section 23 is connected to the second power supply 220, the MOSFETs 13 and 16 can be turned on when the voltage of the second power supply 220 is equal to or higher than the voltage at which the third control circuit section 23 can operate (e.g., 3V). Therefore, power can be supplied from the first power supply 210 to the second circuit 320.

[0058] However, when the voltage of the second power supply 220 drops below the voltage at which the third control circuit section 23 can operate, the MOSFETs 13 and 16 cannot be turned on. Therefore, power cannot be supplied from the first power supply 210 to the second circuit 320. Thus, the first supply mode or the second supply mode is preferable for the supply mode of the operating power.

[0059] Note that the switching of the power supplies 210 and 220 for each of the circuits 310 and 320 will be described later. Also, the abnormality of the first power supply 210 is a situation where the voltage has dropped below the voltage at which the first circuit 310 can operate (e.g., 8V). On the other hand, the abnormality of the second power supply 220 is a situation where the voltage has dropped below the voltage at which the second circuit 320 can operate (e.g., 8V).

[0060] Also, the control circuit 20 may be commonly provided for the plurality of MOSFETs 11 to 18. In this case, the control circuit 20 is supplied with operating power from one power supply. Also, the control circuit 20 may have the second control circuit section 22 and the third control circuit section 23 commonly provided. In this case, the common control circuit that also serves as the first control circuit section 21, the fourth control circuit section 24, the second control circuit section 22, and the third control circuit section 23 is supplied with operating power by OR - connecting two power supplies.

[0061] Furthermore, as shown in FIG. 2, the control circuit 20 includes power supply determination units 25a and 25b, both-end voltage determination units 26a and 26b, a voltage difference determination unit 27a, and overcurrent determination units 28a to 28d. Each determination unit may be provided in each of the control circuit units 21 to 24, or may be provided in common to the control circuit units 21 to 24. The first control circuit unit 21 and the second control circuit unit 22 determine the states of the first main path 1m, the first switching path 3, the power supplies 210 and 220, and the circuits 310 and 320 based on the determination units 25a to 28a and 28c. The third control circuit unit 23 and the fourth control circuit unit 24 determine the states of the second main path 2m, the second switching path 4, the power supplies 210 and 220, and the circuits 310 and 320 based on the determination units 25b, 27a, 26b, 28b, and 28d. Note that the configuration for determining the states of the main paths 1m and 2m, the switching paths 3 and 4, the power supplies 210 and 220, and the circuits 310 and 320 is not limited to the following. For example, the states of the main paths 1m and 2m and the switching paths 3 and 4 are disconnection or a failure of the MOSFET.

[0062] The first power supply determination unit 25a is a part for determining a voltage drop of the first power supply 210. The first power supply determination unit 25a outputs a comparison result between the voltage of the first power supply 210 and a voltage threshold value (VREF). The control circuit units 21 and 22 determine whether the voltage of the first power supply 210 has dropped based on the output value of the first power supply determination unit 25a.

[0063] The second power supply determination unit 25b is a part for determining a voltage drop of the second power supply 220. The second power supply determination unit 25b outputs a comparison result between the voltage of the second power supply 220 and the voltage threshold value (VREF). The control circuit units 23 and 24 determine whether the voltage of the second power supply 220 has dropped based on the output value of the second power supply determination unit 25b.

[0064] The first both-end voltage determination unit 26a is a part for determining the voltage difference across the first main switch unit. The first both-end voltage determination unit 26a outputs a comparison result between the voltage on the upstream side and the voltage on the downstream side of the first main switch unit. Note that the upstream side is the side of the first power supply 210. The downstream side is the side of the first circuit 310.

[0065] The control circuit units 21, 22, and 23 determine the voltage difference across the first main switch unit based on the output value of the first two-terminal voltage determination unit 26a. Then, the control circuit units 21 and 22 determine whether there is a defect (open fault) in either the first MOSFET 11 or the second MOSFET 12 based on the voltage difference across the two terminals. The control circuit units 21 and 22 consider that either the first MOSFET 11 or the second MOSFET 12 has an open fault when the voltage difference across the two terminals is equal to or greater than a predetermined value.

[0066] The second two-terminal voltage determination unit 26b is a part for determining the voltage difference across the second main switch unit. The second two-terminal voltage determination unit 26b outputs the comparison result of the voltage on the upstream side and the voltage on the downstream side of the second main switch unit. Here, the upstream side is the side of the second power supply 220, and the downstream side is the side of the second circuit 320.

[0067] The control circuit units 22, 23, and 24 determine the voltage difference across the second main switch unit based on the output value of the second two-terminal voltage determination unit 26b. Then, the control circuit units 23 and 24 determine whether there is an open fault in either the seventh MOSFET 17 or the eighth MOSFET 18 based on the voltage difference across the two terminals. The control circuit units 23 and 24 consider that either the seventh MOSFET 17 or the eighth MOSFET 18 has an open fault when the voltage difference across the two terminals is equal to or greater than a predetermined value. Here, the predetermined value can also be referred to as the open fault determination value.

[0068] The voltage difference determination unit 27a is a part for determining the magnitude relationship between the voltage of the first power supply 210 and the voltage of the second power supply 220. The voltage difference determination unit 27a outputs the comparison result of the voltage of the first power supply 210 and the voltage of the second power supply 220. The control circuit units 21 to 24 determine the magnitude relationship between the voltage of the first power supply 210 and the voltage of the second power supply 220 based on the output value of the voltage difference determination unit 27a.

[0069] The first overcurrent determination unit 28a is a part for determining the overcurrent in the first main path 1m. The first overcurrent determination unit 28a outputs the voltage across both ends of a current detection resistor provided in the first main wiring 31m. The control circuit units 21, 22 calculate the current value in the first main path 1m based on the resistance value of the current detection resistor and the voltage across both ends. Then, when the current value is equal to or greater than the current threshold, the control circuit units 21, 22 determine that an overcurrent is flowing. Also, when the current value is equal to or greater than the current threshold, the control circuit units 21, 22 determine that an overcurrent is flowing through the first circuit 310 due to a short circuit in the first circuit 310.

[0070] The second overcurrent determination unit 28b is a part for determining the overcurrent in the second main path 2m. The second overcurrent determination unit 28b outputs the voltage across both ends of a current detection resistor provided in the second main wiring 32m. The control circuit units 23, 24 calculate the current value in the second main path 2m based on the resistance value of the current detection resistor and the voltage across both ends. Then, when the current value is equal to or greater than the current threshold, the control circuit units 23, 24 determine that an overcurrent is flowing. Also, when the current value is equal to or greater than the current threshold, the control circuit units 23, 24 determine that an overcurrent is flowing through the second circuit 32 due to a short circuit in the second circuit 32.

[0071] The third overcurrent determination unit 28c is a part for determining the overcurrent in the first sub-path 1s and the first switching path 3. The third overcurrent determination unit 28c outputs the voltage across both ends of a current detection resistor provided in the first sub-wiring 31s. The control circuit units 21, 22 calculate the current value in the first sub-path 1s based on the resistance value of the current detection resistor and the voltage across both ends. Then, when the current value is equal to or greater than the current threshold, the control circuit units 21, 22 determine that an overcurrent is flowing. Also, when the current value is equal to or greater than the current threshold, the control circuit units 21, 22 determine that an overcurrent is flowing through the first circuit 310 due to a short circuit in the first circuit 310.

[0072] The fourth overcurrent determination unit 28d is a part for determining the overcurrent in the second sub-path 2s and the second switching path 4. The fourth overcurrent determination unit 28d outputs the voltage across the current detection resistor provided in the second sub-wiring 32s. The control circuit units 23 and 24 calculate the current value of the second sub-path 2s based on the resistance value of the current detection resistor and the voltage across it. Then, the control circuit units 23 and 24 determine that an overcurrent is flowing when the current value is equal to or greater than the current threshold. Also, when the current value is equal to or greater than the current threshold, the control circuit units 23 and 24 determine that an overcurrent is flowing through the second circuit 320 due to a short circuit in the second circuit 320.

[0073] Note that each of the control circuit units 21 to 24 can also use an ideal diode controller. The power supply switching circuit 101 can simplify the design by using an ideal diode controller as the control circuit units 21 to 24.

[0074] <Operation> Here, the operation of the power supply switching circuit 101 will be described with reference to FIGS. 5 to 10. When power is supplied, the control circuit 20 operates as shown in the normal state of FIG. 7. That is, the first control circuit unit 21 turns on the first MOSFET 11 and the second MOSFET 12 to turn on the first main path 1m. The fourth control circuit unit 24 turns on the seventh MOSFET 17 and the eighth MOSFET 18 to turn on the second main path 2m.

[0075] Note that in FIG. 7 and the like, on is described as ON and off as OFF. Also, the state where only the first power supply 210 is abnormal is shown as the abnormal state of PS1 in FIG. 7. The state where only the second power supply 220 is abnormal is shown as the abnormal state of PS2. Also, PS1 abnormality means a voltage drop and power cut-off of the first power supply 210. Similarly, PS2 abnormality means a voltage drop and power cut-off of the second power supply 220. The state where only the first circuit 310 has a short circuit fault is shown as the short circuit of CKT1. The state where only the second circuit 320 has a short circuit fault is shown as the short circuit of CKT2.

[0076] Also, the control circuit 20 starts the flowcharts of FIGS. 5 and 6 at a predetermined timing when power is supplied. The predetermined timing is, for example, the timing when the ignition switch of the vehicle is turned on, the timing of a predetermined cycle, or the timing when an interrupt occurs. Also, the control circuit 20 starts the flowchart of FIG. 5 and the flowchart of FIG. 6 at different timings.

[0077] First, the flowchart of FIG. 5 will be described. In step S1, initial switch control is performed. In the situation of step S1, all the MOSFETs 11 to 18 are off. From that state, the control circuit 20 turns on the first main path 1m and the second main path 2m. That is, the first control circuit unit 21 turns on the first MOSFET 11 and the second MOSFET 12. Also, the fourth control circuit unit 24 turns on the seventh MOSFET 17 and the eighth MOSFET 18.

[0078] In step S2, it is determined whether an overcurrent is flowing through the first circuit 310. The control circuit units 21 and 22 determine whether an overcurrent is flowing through the first circuit 310 using the output result of the first overcurrent determination unit 28a. If the control circuit units 21 and 22 determine that an overcurrent is flowing, they consider that the first circuit 310 is short-circuited and proceed to step S3. On the other hand, if the control circuit units 21 and 22 determine that no overcurrent is flowing, they consider that the first circuit 310 is not short-circuited and proceed to step S10. Note that the control circuit 20 may determine whether an overcurrent is flowing through the first circuit 320 using the output result of the third overcurrent determination unit 28c after the path is switched.

[0079] In step S3, the first main path 1m is turned off and the first switching path 3 is turned off. As shown in FIG. 10, the first control circuit unit 21 turns off the first main path 1m by turning off the first MOSFET 11 and the second MOSFET 12. Also, the second control circuit unit 22 turns off the first switching path 3 by turning off the fifth MOSFET 15 and the fourth MOSFET 14. Thereby, the power supply switching circuit 101 can suppress the current from continuing to flow through the first circuit 310.

[0080] Step S10 is the first switching process. The first switching process includes steps S11 to S17.

[0081] In step S11, it is determined whether the first power supply 210 is equal to or lower than the voltage threshold. The control circuit units 21 and 22 determine whether the voltage of the first power supply 210 is equal to or lower than the voltage threshold using the output result of the first power supply determination unit 25a. If the control circuit units 21 and 22 determine that it is equal to or lower than the voltage threshold, they proceed to step S14. If they determine that it is not equal to or lower than the voltage threshold, they proceed to step S12.

[0082] In step S14, it is determined whether the second power supply 220 ≥ the first power supply 210. The control circuit units 21 and 22 determine whether the voltage of the second power supply 220 is equal to or higher than the voltage of the first power supply 210 using the output result of the voltage difference determination unit 27a. If the control circuit units 21 and 22 determine that the voltage of the second power supply 220 is equal to or higher than the voltage of the first power supply 210, they regard the first power supply 210 as abnormal and proceed to step S15. If the control circuit units 21 and 22 determine that the voltage of the second power supply 220 is not equal to or higher than the voltage of the first power supply 210, they do not regard the first power supply 210 as abnormal and proceed to step S12.

[0083] In step S12, the first switching path 3 is turned off. The second control circuit unit 22 turns off the first switching path 3 by turning off the fifth MOSFET 15 and the fourth MOSFET 14. In step S13, the first main path 1m is turned on. The first control circuit unit 21 turns on the first main path 1m by turning on the first MOSFET 11 and the second MOSFET 12. In this way, when the control circuit 20 does not regard the first power supply 210 as abnormal, it turns off the first switching path 3 and turns on the first main path 1m.

[0084] Note that turning on a path is the same as turning on the MOSFETs 11 to 18 included in that path. Similarly, turning off a path is the same as turning off the MOSFETs 11 to 18 included in that path.

[0085] In step S15, the first main path 1m is turned off. The first control circuit section 21 turns off the first main path 1m by turning off the first MOSFET 11 and the second MOSFET 12.

[0086] In step S16, the second switching path 4 is turned off. The third control circuit section 23 turns off the second switching path 4 by turning off the third MOSFET 13 and the sixth MOSFET 16.

[0087] In step S17, the first switching path 3 is turned on. The second control circuit section 22 turns on the first switching path 3 by turning on the fifth MOSFET 15 and the fourth MOSFET 14. As shown in FIG. 9, when the control circuit 20 determines that the first power supply 210 is abnormal, it turns off the first main path 1m and turns on the first switching path 3.

[0088] In this way, the control circuit 20 turns off one of the first switching path 3 and the second switching path 4 before turning on the other. In this regard, a situation where the voltage of the first power supply 210 drops from 12V to 7V while the voltage of the second power supply 220 is 8V will be used for explanation.

[0089] First, before the voltage of the first power supply 210 drops, the first main path 1m and the second switching path 4 are on, and the second main path 2m and the first switching path 3 are off. After that, when the voltage of the first power supply 210 drops to 7V, the voltage of the first power supply 210 becomes lower than that of the second power supply 220.

[0090] When the voltage of the first power supply 210 drops to 7V and the second switching path 4 remains on, a large current will flow from the second power supply 220 to the first power supply 210. That is, the current flows through the body diode of the off-state fifth MOSFET 15 and the on-state third MOSFET 13 to the first power supply 210. Therefore, the body diode of the fifth MOSFET 15 may consume power exceeding the rated power and fail. Therefore, the control circuit 20 must turn off the other switching path before one switching path is turned on.

[0091] In step S4, it is determined whether an overcurrent is flowing through the second circuit 320. The control circuit units 23 and 24 determine whether an overcurrent is flowing through the second circuit 320 by using the output result of the second overcurrent determination unit 28b. If the control circuit units 23 and 24 determine that an overcurrent is flowing, they regard the second circuit 320 as being short-circuited and proceed to step S5. On the other hand, if the control circuit units 23 and 24 determine that no overcurrent is flowing, they regard the second circuit 320 as not being short-circuited and proceed to step S20. Note that the control circuit 20 may determine whether an overcurrent is flowing through the second circuit 320 by using the output result of the fourth overcurrent determination unit 28d after the path switching.

[0092] In step S5, the second main path 2m is turned off and the second switching path 4 is turned off. The fourth control circuit unit 24 turns off the second main path 2m by turning off the seventh MOSFET 17 and the eighth MOSFET 18. Also, the third control circuit unit 23 turns off the second switching path 4 by turning off the third MOSFET 13 and the sixth MOSFET 16. Thereby, the power supply switching circuit 101 can suppress the current from continuously flowing through the second circuit 320.

[0093] Step S20 is the second switching process. The second switching process includes steps S21 to S27.

[0094] In step S21, it is determined whether the voltage of the second power supply 220 is equal to or lower than the voltage threshold. The control circuit units 23 and 24 determine whether the voltage of the second power supply 220 is equal to or lower than the voltage threshold by using the output result of the second power supply determination unit 25b. If the control circuit units 23 and 24 determine that the voltage is equal to or lower than the voltage threshold, they proceed to step S24. If they determine that the voltage is not equal to or lower than the voltage threshold, they proceed to step S22.

[0095] In step S24, it is determined whether the first power supply 210 ≥ the second power supply 220. The control circuit units 23 and 24 determine whether the voltage of the first power supply 210 is greater than or equal to the voltage of the second power supply 220 using the output result of the voltage difference determination unit 27a. If the control circuit units 23 and 24 determine that the voltage of the first power supply 210 is greater than or equal to the voltage of the second power supply 220, they regard the second power supply 220 as abnormal and proceed to step S25. If the control circuit units 23 and 24 determine that the voltage of the first power supply 210 is not greater than or equal to the voltage of the second power supply 220, they do not regard the second power supply 220 as abnormal and proceed to step S22.

[0096] In step S22, the second switching path 4 is turned off. The third control circuit unit 23 turns off the second switching path 4 by turning off the third MOSFET 13 and the sixth MOSFET 16. In step S23, the second main path 2m is turned on. The fourth control circuit unit 24 turns on the second main path 2m by turning on the seventh MOSFET 17 and the eighth MOSFET 18. In this way, when the control circuit 20 does not regard the second power supply 220 as abnormal, it turns off the second switching path 4 and turns on the second main path 2m.

[0097] In step S25, the second main path 2m is turned off. The fourth control circuit unit 24 turns off the second main path 2m by turning off the seventh MOSFET 17 and the eighth MOSFET 18.

[0098] In step S26, the first switching path 3 is turned off. The second control circuit unit 22 turns off the first switching path 3 by turning off the fourth MOSFET 14 and the fifth MOSFET 15. Step S26 turns off the first switching path 3 for the same reason as step S16.

[0099] In step S27, the second switching path 4 is turned on. The third control circuit unit 23 turns on the second switching path 4 by turning on the third MOSFET 13 and the sixth MOSFET 16. When the control circuit 20 regards the second power supply 220 as abnormal, it turns off the second main path 2m and turns on the second switching path 4.

[0100] In this way, even when a short - circuit fault occurs in the first circuit 310, the control circuit 20 forms a power supply path that does not affect the operation of the second circuit 320. Similarly, even when a short - circuit fault occurs in the second circuit 320, the control circuit 20 forms a power supply path that does not affect the operation of the first circuit 310.

[0101] That is, when a short - circuit fault occurs in one of the first circuit 310 and the second circuit 320, the power supply switching circuit 101 forms a power supply path so that power is supplied to the other circuit. Therefore, the power supply switching circuit 101 can maintain the operation of the circuit in which no short - circuit fault has occurred among the first circuit 310 and the second circuit 320.

[0102] Furthermore, even when one of the power supplies 210, 220 is abnormal, the power supply switching circuit 101 can supply power from the normal power supply to the circuits 310, 320. For example, when the first power supply 210 is abnormal, power can be supplied from the second power supply 220 to the first circuit 310 and the second circuit 320.

[0103] By the way, when power is supplied from one power supply to both circuits 310, 320, a power supply switching circuit including MOSFETs through which the currents of both circuits 310, 320 flow can be considered. The MOSFET needs to have a power - handling margin so that it can conduct the currents of both circuits 310, 320.

[0104] However, only the current of either the first circuit 310 or the second circuit 320 flows through each of the MOSFETs 11 - 18. Therefore, the power supply switching circuit 101 does not need to provide a margin for the power - handling capacity of each of the MOSFETs 11 - 18 to cope with abnormal situations. That is, the power supply switching circuit 101 can be adopted without using MOSFETs 11 - 18 with a power - handling margin. Thus, the cost and size of each of the MOSFETs 11 - 18 can be reduced.

[0105] In step S6, it is determined whether all switches are off. Each control circuit unit 21 to 24 ends the flowchart of FIG. 5 when it determines that the corresponding MOSFETs 11 to 18 are off, and returns to step S2 when it determines that they are not off. The state where all switches are off is a state where the power supplies 210 and 220 have dropped below the voltage at which they cannot turn on all the MOSFETs 11 to 18, or a state where both power supplies 210 and 220 have been disconnected.

[0106] Next, the flowchart of FIG. 6 will be described. In FIG. 6, the step numbers of the processes similar to those in FIG. 5 are given an "a".

[0107] The control circuit 20 executes step S1 in the same manner as the above flowchart. After that, it executes step S10a and step S20a.

[0108] Step S10a is the first failure determination process. The first failure determination process is a process of determining an open failure of the MOSFETs 11 and 12 in the first main path 1m and switching the path based on the determination result.

[0109] In step S11a, it is determined whether the voltage difference across the SW is greater than or equal to a predetermined value. The control circuit units 21 and 22 determine whether the voltage difference across the first main switch unit is greater than or equal to a predetermined value based on the output value of the first voltage difference determination unit 26a. When the control circuit units 21 and 22 determine that the voltage difference is greater than or equal to the predetermined value, they assume that either the first MOSFET 11 or the second MOSFET 12 has an open failure and proceed to step S14a. When the control circuit units 21 and 22 determine that the voltage difference is not greater than or equal to the predetermined value, they assume that the first MOSFET 11 and the second MOSFET 12 do not have an open failure and proceed to step S13a.

[0110] Step S14a determines whether the first power supply 210 ≥ the second power supply 220. Similar to step S14, the control circuit units 21 and 22 make the determination using the output result of the voltage difference determination unit 27a. If the control circuit units 21 and 22 determine that the voltage of the first power supply 210 is greater than or equal to the voltage of the second power supply 220, they proceed to step S17a. If the control circuit units 21 and 22 determine that the voltage of the first power supply 210 is not greater than or equal to the voltage of the second power supply 220, they proceed to step S16a.

[0111] Step S13a selects the first main path 1m. The first control circuit unit 21 selects the first main path 1m as the path to be turned on, rather than turning it on.

[0112] Step S16a selects the first switching path 3. The second control circuit unit 22 selects the first switching path 3 as the path to be turned on, rather than turning it on.

[0113] Step S17a selects the first sub-path 1s. The second control circuit unit 22 and the third control circuit unit 23 select the first sub-path 1s. At this time, the second control circuit unit 22 selects the fourth MOSFET 14 of the first sub-path 1s. The third control circuit unit 23 selects the third MOSFET 13 of the first sub-path 1s according to the instruction from the second control circuit unit 22. The second control circuit unit 22 selects the fourth MOSFET 14 as the switch to be turned on, rather than turning it on. The third control circuit unit 23 selects the third MOSFET 13 as the switch to be turned on, rather than turning it on.

[0114] Step S20a is the second fault determination process. The second fault determination process is a process of determining the open faults of the MOSFETs 17 and 18 in the second main path 2m and switching the path based on the determination result.

[0115] Step S21a determines whether the voltage difference across the SW is greater than or equal to a predetermined value. Based on the output value of the second voltage difference determination unit 26b, the control circuit units 23 and 24 determine whether the voltage difference across the second main switch unit is greater than or equal to a predetermined value. If the control circuit units 23 and 24 determine that the voltage difference is greater than or equal to the predetermined value, they assume that either the 7th MOSFET 17 or the 8th MOSFET 18 has an open fault and proceed to step S24a. If the control circuit units 23 and 24 determine that the voltage difference is not greater than or equal to the predetermined value, they assume that the 7th MOSFET 17 and the 8th MOSFET 18 do not have an open fault and proceed to step S23a.

[0116] Step S24a determines whether the first power supply 210 ≥ the second power supply 220. Similar to step S24, the control circuit units 23 and 24 make the determination using the output result of the voltage difference determination unit 27a. If the control circuit units 23 and 23 determine that the voltage of the first power supply 210 is greater than or equal to the voltage of the second power supply 220, they proceed to step S27a. If the control circuit units 23 and 24 determine that the voltage of the first power supply 210 is not greater than or equal to the voltage of the second power supply 220, they proceed to step S26a.

[0117] Step S23a selects the second main path 2m. The fourth control circuit unit 24 selects the second main path 2m as the path to be turned on, rather than turning it on.

[0118] Step S26a selects the second sub-path 2s. The second control circuit unit 22 and the third control circuit unit 23 select the second sub-path 2s. At this time, the third control circuit unit 23 selects the 6th MOSFET 16 of the second sub-path 2s. The second control circuit unit 22 selects the 5th MOSFET 15 of the second sub-path 2s in response to the instruction from the third control circuit unit 23. The third control circuit unit 23 selects the 6th MOSFET 16 as the switch to be turned on, rather than turning it on. The second control circuit unit 22 selects the 5th MOSFET 15 as the switch to be turned on, rather than turning it on.

[0119] Step S27a selects the second switching path 4. The third control circuit section 23 selects the second switching path 4 as the path to be turned on, rather than turning it on.

[0120] In step S6a, the non-selected switch is turned off. Each of the control circuit sections 21 to 24 turns off the switch (non-selected switch) that is not selected as the switch to be turned on. This can prevent the current from flowing backward to the power supplies 210 and 220.

[0121] In step S6b, the selected switch is turned on. Each of the control circuit sections 21 to 24 turns on the switch selected as described above.

[0122] As shown in FIG. 8, when the second MOSFET 12 has an open fault, if the determination in step S14a is YES, the first sub-path 1s is turned on. When the second MOSFET 12 has an open fault, if the determination in step S14a is NO, the first switching path 3 is turned on.

[0123] Also, when the eighth MOSFET 18 has an open fault, if the determination in step S24a is YES, the second switching path 4 is turned on. When the eighth MOSFET 18 has an open fault, if the determination in step S24a is NO, the first sub-path 1s is turned on.

[0124] In this way, even when an open fault occurs in the first main path 1m, the control circuit 20 forms a power supply path so that power is supplied to the first circuit 310. Similarly, even when an open fault occurs in the second main path 2m, the control circuit 20 forms a power supply path so that power is supplied to the second circuit 320. Therefore, even when an open fault occurs in the main paths 1m and 2m, the control circuit 20 can maintain the operation of the circuits 310 and 320.

[0125] (Modification 1) With reference to FIGS. 11 and 12, Modification 1 will be described. In Modification 1, the operation of the control circuit 20 is different from that in the above embodiment. In FIG. 11, b is added to the step numbers of the processes similar to those in FIG. 5.

[0126] Similar to the above embodiment, the control circuit 20 executes step S1. After that, steps S10b and S20b are executed.

[0127] Step S10b is a modification of the first switching process. Step S10b includes step S13b instead of steps S12 and S13. Step S10b includes step S16b instead of steps S15 and S16.

[0128] When the first control circuit section 21 determines NO in step S11, it executes step S13b. Step S13b is the same as step S13a.

[0129] When the second control circuit section 22 determines YES in step S14, it executes step S16b. Step S16b is the same as step S16a.

[0130] Step S20b is a modification of the second switching process. Step S20b includes step S23b instead of steps S22 and S23. Step S10b includes step S26b instead of steps S25 and S26.

[0131] When the fourth control circuit section 24 determines NO in step S21, it executes step S23b. Step S23b is the same as step S13a.

[0132] When the third control circuit section 23 determines YES in step S24, it executes step S26b. Step S26b is the same as step S27a.

[0133] When the process of step S20b ends, control circuit 20 executes step S7. In step S7, it is determined whether there is a path change. In the first switching process S10b and the second switching process S20b, if the path is changed, control circuit 20 proceeds to step S8, and if the path is not changed, it proceeds to step S6a. That is, when there is no change in the power supply path, control circuit 20 does not enter the low-consumption mode and continues to operate as it is.

[0134] In step S8, a low-consumption mode operation is executed. Control circuit 20 instructs the first circuit 310 and the second circuit 320 to operate in the low-consumption mode. That is, control circuit 20 temporarily sets the first circuit 310 and the second circuit 320 to a low-load state. The operation in the low-consumption mode can also be said to be a low-load operation. The low-consumption mode is, for example, operation stop or intermittent operation.

[0135] Note that when control circuit 20 selects the first switching path 3, it may set only the first circuit 310 to the low-load state. Similarly, when control circuit 20 selects the second switching path 4, it may set only the second circuit 320 to the low-load state.

[0136] Steps S6a and S6b are the same as above. That is, after control circuit 20 turns off the non-selected switch, it turns on the selected switch while the first circuit 310 and the second circuit 320 are operating in the low-consumption mode. As shown in FIG. 12, for example, when the first power supply 210 is abnormal, the power supply switching circuit 101 turns off the first main path 1m and turns on the first switching path 3 while the first circuit 310 is operating in the low-consumption mode.

[0137] In this way, when the control circuit 20 switches the power supply path from the first main path 1m to the first switching path 3, it turns on the first switching path 3 with the first circuit 310 operating in the low power consumption mode. Also, when the control circuit 20 switches the power supply path from the second main path 2m to the second switching path 4, it turns on the second switching path 4 with the second circuit 320 operating in the low power consumption mode. Thus, the power supply switching circuit 101 can suppress voltage fluctuations during path switching. Note that in Modification 1, the above steps S2 to S5 may be executed.

[0138] (Modification 2) Modification 2 will be described with reference to FIGS. 13, 14, and 15. The operation of the control circuit 20 is different from that of the above-described embodiment. The control circuit 20 changes the switching process depending on whether the power supplies 210 and 220 are chargeable. In FIGS. 13 to 15, the same step numbers are assigned to the same processes as in FIG. 5.

[0139] The control circuit 20 executes step S1 as in the above-described embodiment. Thereafter, it executes step S51.

[0140] In step S51, it is determined whether the first power supply 210 is chargeable. The first control circuit section 21 and the second control circuit section 22 determine whether the first power supply 210 is a secondary battery that can be charged or a primary battery that cannot be charged. For example, the first control circuit section 21 and the second control circuit section 22 are configured to be able to acquire power supply information indicating whether the first power supply 210 is chargeable. The first control circuit section 21 and the second control circuit section 22 determine whether the first power supply 210 is chargeable based on the power supply information. If the first control circuit section 21 and the second control circuit section 22 determine that it is chargeable, they proceed to step S30, and if they determine that it is not chargeable, they proceed to step S10.

[0141] As shown in FIG. 14, step S30 executes steps S11 and S14 in the same manner as step S10. When a NO determination is made in step S11, step S12 is executed after step S13. Also, when a YES determination is made in step S14, steps S17 and S15 are executed in this order after step S16. Here too, the control circuit 20 always turns off the other switching path before one switching path is turned on.

[0142] In step S52, it is determined whether the second power source 220 is chargeable. Similar to the first power source 210, the third control circuit unit 23 and the fourth control circuit unit 24 determine whether the second power source 220 is a secondary battery that can be charged or a primary battery that cannot be charged. If the third control circuit unit 23 and the fourth control circuit unit 24 determine that it is chargeable, they proceed to step S40, and if they determine that it is not chargeable, they proceed to step S20.

[0143] As shown in FIG. 15, step S40 executes steps S21 and S24 in the same manner as step S20. When a NO determination is made in step S21, step S22 is executed after step S23. Also, when a YES determination is made in step S24, steps S27 and S25 are executed in this order after step S26. Here too, the control circuit 20 always turns off the other switching path before one switching path is turned on Note that the control circuit 20 may process steps S51, S10, S30 and steps S52, S20, S40 in parallel. Also, steps S51 and S52 may be executed by any one of the plurality of control circuit units 21 to 24. In this case, the control circuit unit transmits the determination results of steps S51 and S52 to the other control circuit units. Alternatively, the control circuit unit stores the determination results of steps S51 and S52 in a storage device so that they can be referred to by the other control circuit units.

[0144] When the control circuit 20 switches from the first main path 1m to the first switching path 3, if the first power supply 210 can be charged, it forms a power supply path so that the first power supply 210 and the second power supply 220 are temporarily connected to the first circuit 310. Similarly, when the control circuit 20 switches from the second main path 2m to the second switching path 4, if the second power supply 220 can be charged, it forms a power supply path so that the first power supply 210 and the second power supply 330 are temporarily connected to the second circuit 320. Therefore, when the power supplies 210 and 220 can be charged, the power supply switching circuit 101 can suppress voltage fluctuations during switching.

[0145] Also, when the control circuit 20 switches from the first main path 1m to the first switching path 3, if the first power supply 210 cannot be charged, it forms a power supply path so that the first power supply 210 and the second power supply 220 are not connected to the first circuit 310. Similarly, when the control circuit 20 switches from the second main path 2m to the second switching path 4, if the second power supply 220 cannot be charged, it forms a power supply path so that the first power supply 210 and the second power supply 220 are not connected to the second circuit 320. Therefore, when the power supplies 210 and 220 cannot be charged, the power supply switching circuit 101 can suppress the backflow of current and prevent the power supplies 210 and 220 from deteriorating or being damaged.

[0146] The power supply switching circuit 101 of Modification 2 can achieve the same effects as the above-described embodiment. Also, the power supply switching circuit 101 of Modification 2 can be used whether the power supplies 210 and 220 can be charged or not. That is, the power supply switching circuit 101 of Modification 2 can perform power supply switching generally. Note that the power supply switching circuit 101 of Modification 2 may execute the above steps S2 to S5. In this case, the power supply switching circuit 101 of Modification 2 can perform power supply switching generally and maintain the operation of the circuit in which no short-circuit fault has occurred among the first circuit 310 and the second circuit 320. Note that the power supply switching circuit 101 may be configured to be capable of executing only one of the first switching process and the third switching process, and only one of the second switching process and the fourth switching process, depending on whether the power supplies 210 and 220 can be charged.

[0147] The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure. Hereinafter, as other forms of the present disclosure, the second to fourth embodiments will be described. The above embodiments and the second to fourth embodiments can be implemented independently, but can also be implemented in appropriate combination. The present disclosure can be implemented by various combinations without being limited to the combinations shown in the embodiments.

[0148] (Second Embodiment) The power supply switching circuit 102 of the second embodiment will be described with reference to FIG. 16. The power supply path for supplying power to the control circuit 20 is different from that of the power supply switching circuit 101. Regarding the operation of the control circuit 20, it is the same as that of the above embodiments (including modified examples). In FIG. 16, the gate wiring 40 is omitted.

[0149] As shown in FIG. 16, the power supply switching circuit 102 includes a first operating power supply path 34 and a second operating power supply path 35. The first operating power supply path 34 includes a first diode 36. The second operating power supply path 35 includes a second diode 37. The control circuit 20 is connected to the first power supply 210 via the first operating power supply path 34 and is connected to the second power supply 220 via the second operating power supply path 35. In this way, the control circuit 20 is configured to be able to supply power from either the first power supply 210 or the second power supply 220. It can also be said that the power supply switching circuit 102 is configured by OR-connecting the power supplies 210 and 220 to the control circuit 20.

[0150] The power supply switching circuit 102 can achieve the same effect as the power supply switching circuit 101. Further, even if a power supply abnormality occurs in one of the power supplies 210 and 220, the power supply switching circuit 102 can perform the switching process by the control circuit 20.

[0151] (Third Embodiment) With reference to FIG. 17, the power supply switching circuit 103 of the third embodiment will be described. The power supply path for supplying power to the control circuit 20 of the power supply switching circuit 103 is different from that of the power supply switching circuit 101. Regarding the operation of the control circuit 20, it is the same as in the above embodiments (including the modified examples). In FIG. 17, the gate wiring 40 is omitted.

[0152] As shown in FIG. 17, the power supply switching circuit 103 includes an operating power supply path 38. The operating power supply path 38 connects the switching wiring 33 and the control circuit 20. In this way, similar to the second embodiment, the control circuit 20 is configured to be capable of being powered by either the first power supply 210 or the second power supply 220. It can also be said that the power supply switching circuit 103 is configured by OR - connecting the power supplies 210 and 220 to the control circuit 20.

[0153] The power supply switching circuit 103 can achieve the same effects as the power supply switching circuit 101. Further, even if a power supply abnormality occurs in one of the power supplies 210 and 220, the power supply switching circuit 103 can perform the switching process by the control circuit 20.

[0154] (Fourth Embodiment) With reference to FIGS. 18 to 20, the power supply switching circuit 104 of the fourth embodiment will be described. The power supply switching circuit 104 is different from the power supply switching circuit 101 in that it includes mechanical switches 11a, 13a to 17a instead of MOSFETs 11 to 18. In FIG. 18, the wiring for turning on and off the mechanical switches 11a, 13a to 17a is omitted.

[0155] The power supply switching circuit 104 includes a first mechanical switch 11a, a third mechanical switch 13a, a fourth mechanical switch 14a, a fifth mechanical switch 15a, a sixth mechanical switch 16a, and a seventh mechanical switch 17a.

[0156] The first main path 1m includes the first mechanical switch 11a and the first main wiring 31m. The first mechanical switch 11a is a substitute for the first semiconductor switching element. The first sub - path 1s includes the third mechanical switch 13a, the fourth mechanical switch 14a, and the first sub - wiring 31s.

[0157] The second main path 2m includes a seventh mechanical switch 17a and a second main wiring 32m. The seventh mechanical switch 17a substitutes for the second semiconductor switching element. The second sub-path 2s includes a fifth mechanical switch 15a, a sixth mechanical switch 16a, and a second sub-wiring 32s.

[0158] The first switching path 3 includes a fifth mechanical switch 15a, a fourth mechanical switch 14a, a part of the second sub-wiring 32s, a part of the first sub-wiring 31s, and a switching wiring 33. The fourth mechanical switch 14a and the fifth mechanical switch 15a substitute for the third semiconductor switching element.

[0159] The second switching path 4 includes a third mechanical switch 13a, a sixth mechanical switch 16am, a part of the first sub-wiring 31s, a part of the second sub-wiring 32s, and a switching wiring 33. The third mechanical switch 13a and the sixth mechanical switch 16a substitute for the fourth semiconductor switching element.

[0160] As shown in FIG. 19, the control circuit 20 performs on / off control of each mechanical switch 11a, the third mechanical switch 13a, the fourth mechanical switch 14a, the fifth mechanical switch 15a, the sixth mechanical switch 16a, and the seventh mechanical switch 17a. Further, similar to the above embodiment, the control circuit 20 determines short-circuit faults and open faults, and performs processing operations when a fault is determined. Also, as shown in FIG. 20, the power supply switching circuit 104 can configure the wiring board 30 without using vias or the like.

[0161] The power supply switching circuit 104 can achieve the same effect as the power supply switching circuit 101. Further, mechanical switches 11a, 17a, etc. can block bidirectional current when switched off. Therefore, the power supply switching circuit 104 can reduce the number of switches in the main paths 1m, 2m to one.

[0162] Although the present disclosure has been described in accordance with embodiments, it is understood that the present disclosure is not limited to such embodiments or structures. The present disclosure also encompasses various modifications and variations within the equivalent scope. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms that include only one element, more than one element, or less than one element thereof also fall within the scope and spirit of the present disclosure.

[0163] (Disclosure of Technical Ideas) This specification discloses a plurality of technical ideas described in a plurality of claims listed below. Some claims may be described in a multiple dependent form that alternatively cites a preceding claim in subsequent claims. Further, some claims may be described in a multiple dependent form that refers to another multiple dependent form claim. The claims described in these multiple dependent forms define a plurality of technical ideas.

[0164] (Technical Idea 1) A power supply switching circuit connected to a first power supply (210) and a second power supply (220) and also connected to a first circuit (310) and a second circuit (320), a first main path (1m) for supplying power from the first power supply to the first circuit, a second main path (2m) for supplying power from the second power supply to the second circuit, a first switching path (3) for switching the power supply source to the first circuit from the first power supply to the second power supply when the first power supply is abnormal, a second switching path (4) for switching the power supply source to the second circuit from the second power supply to the first power supply when the second power supply is abnormal, and a control circuit (20) for forming a power supply path by controlling each of the first main path, the second main path, the first switching path, and the second switching path to be in either a conductive state or a non-conductive state. The control circuit forms a power supply path that does not affect the operation of the other circuit when a malfunction occurs in one of the first circuit and the second circuit. A power supply switching circuit characterized by this.

[0165] (Technical idea 2) The power supply switching circuit according to Technical Idea 1, characterized in that the first main path, the second main path, the first switching path, and the second switching path are formed on the same plane of the wiring board.

[0166] (Technical idea 3) The first main path includes two first semiconductor switching elements (11, 12) with the cathodes of the body diodes connected to each other. One end is connected to the first power supply, and the other end is connected to the first circuit. The second main path includes two second semiconductor switching elements (17, 18) with the cathodes of the body diodes connected to each other. One end is connected to the second power supply, and the other end is connected to the second circuit. The first switching path includes two third semiconductor switching elements (14, 15) with the cathodes of the body diodes connected to each other via a switching wiring (33). One end is connected to the second power supply, and the other end is connected to the first circuit. The second switching path includes two fourth semiconductor switching elements (13, 16) with the cathodes of the body diodes connected to each other via the switching wiring. One end is connected to the first power supply, and the other end is connected to the second circuit. The power supply switching circuit according to Technical Idea 1 or 2, characterized by this.

[0167] (Technical idea 4) The control circuit includes a first control unit (21) that controls the first semiconductor switching element, a second control unit (24) that controls the second semiconductor switching element, a third control unit (22) that controls the third semiconductor switching element, and a fourth control unit (23) that controls the fourth semiconductor switching element. The power supply switching circuit according to Technical Idea 3, characterized by this.

[0168] (Technical Idea 5) Each control unit is a power supply switching circuit described in Technical Idea 4, characterized in that operating power is individually supplied thereto.

[0169] (Technical Idea 6) The control circuit is a power supply switching circuit described in Technical Idea 4, characterized in that it can be powered from either the first power supply or the second power supply.

[0170] (Technical Idea 7) The control circuit is a power supply switching circuit according to any one of Technical Ideas 3 to 6, characterized in that the control circuit is an ideal diode controller.

[0171] (Technical Idea 8) When the control circuit switches from the first main path to the first switching path 3, if the first power supply is chargeable, the power supply path is formed such that the first power supply and the second power supply are temporarily connected to the first circuit. When switching from the second main path to the second switching path 4, if the second power supply is chargeable, the power supply path is formed such that the first power supply and the second power supply are temporarily connected to the second circuit. The power supply switching circuit according to any one of Technical Ideas 1 to 7 is characterized in that.

[0172] (Technical Idea 9) When the control circuit switches from the first main path to the first switching path 3, if the first power supply is not chargeable, the power supply path is formed such that the first power supply and the second power supply are not connected to the first circuit. When switching from the second main path to the second switching path 4, if the second power supply is not chargeable, the power supply path is formed such that the first power supply and the second power supply are not connected to the second circuit. The power supply switching circuit according to any one of Technical Ideas 1 to 7 is characterized in that.

[0173] (Technical Idea 10) The wiring connecting the first switching path and the first circuit is connected to a first capacitor (61). The wiring connecting the second switching path and the second circuit is characterized in that a second capacitor (62) is connected thereto. The power supply switching circuit according to any one of technical ideas 1 to 9.

[0174] (Technical idea 11) When the control circuit switches the power supply path from the first main path to the first switching path, after setting the first circuit to a low load state, the first switching path is set to a conductive state. When switching the power supply path from the second main path to the second switching path, after setting the second circuit to a low load state, the second switching path is set to a conductive state. The power supply switching circuit according to any one of technical ideas 1 to 10.

[0175] (Technical idea 12) When a problem occurs in the first main path or the second main path, the control circuit forms the power supply path so that power is supplied to the first circuit and the second circuit. The power supply switching circuit according to any one of technical ideas 3 to 6.

[0176] (Technical idea 13) Before making one of the first switching path and the second switching path conductive, the control circuit makes the other non-conductive. The power supply switching circuit according to any one of technical ideas 1 to 12.

Explanation of reference numerals

[0177] 1m…First main path, 2m…Second main path, 1s…First sub-path, 2s…Second sub-path, 3…First switching path, 4…Second switching path, 11…First MOSFET, 12…Second MOSFET, 13…Third MOSFET, 14…Fourth MOSFET, 15…Fifth MOSFET, 16…Sixth MOSFET, 17…Seventh MOSFET, 18…Eighth MOSFET, 11a…First mechanical switch, 13a…Third mechanical switch, 14a…Fourth mechanical switch, 15a…Fifth mechanical switch, 16a…Sixth mechanical switch, 17a…Seventh mechanical switch, 20…Control circuit, 21…First control circuit section, 22…Second control circuit section, 23…Third control circuit section, 24…Fourth control circuit section, 30…Wiring board, 61…First capacitor, 62…Second capacitor, 101~104…Power switching circuit, 210…First power supply, 220…Second power supply, 310…First circuit, 320…Second circuit

Claims

1. A power supply switching circuit connected to a first power supply (210) and a second power supply (220) and also connected to a first circuit (310) and a second circuit (320), a first main path (1m) for supplying power from the first power supply to the first circuit, a second main path (2m) for supplying power from the second power supply to the second circuit, a first switching path (3) for switching the power supply source to the first circuit from the first power supply to the second power supply when the first power supply is abnormal, a second switching path (4) for switching the power supply source to the second circuit from the second power supply to the first power supply when the second power supply is abnormal, and a control circuit (20) for forming a power supply path by controlling each of the first main path, the second main path, the first switching path, and the second switching path to be in either a conductive state or a non-conductive state. The control circuit forms the power supply path that does not affect the operation of the other circuit when a malfunction occurs in one of the first circuit and the second circuit. A power supply switching circuit characterized by this.

2. The power supply switching circuit according to claim 1, wherein the first main path, the second main path, the first switching path, and the second switching path are formed on the same plane of a wiring board.

3. The first main path includes two first semiconductor switching elements (11, 12) with the cathodes of body diodes connected to each other, one end being connected to the first power supply and the other end being connected to the first circuit, the second main path includes two second semiconductor switching elements (17, 18) with the cathodes of body diodes connected to each other, one end being connected to the second power supply and the other end being connected to the second circuit, the first switching path includes two third semiconductor switching elements (14, 15) with the cathodes of body diodes connected to each other via a switching wiring (33), one end being connected to the second power supply and the other end being connected to the first circuit, The second switching path includes two fourth semiconductor switching elements (13, 16) in which cathodes of body diodes are connected via the switching wiring, one end of which is connected to the first power supply and the other end of which is connected to the second circuit. The power supply switching circuit according to claim 1 or 2, characterized in that.

4. The control circuit includes a first control unit (21) for controlling the first semiconductor switching element, a second control unit (24) for controlling the second semiconductor switching element, a third control unit (22) for controlling the third semiconductor switching element, and a fourth control unit (23) for controlling the fourth semiconductor switching element. The power supply switching circuit according to claim 3, characterized in that.

5. Each control unit is characterized in that operating power is supplied individually. The power supply switching circuit according to claim 4.

6. The control circuit is characterized in that it can be powered from either the first power supply or the second power supply. The power supply switching circuit according to claim 4.

7. The control circuit is an ideal diode controller. The power supply switching circuit according to claim 3, characterized in that.

8. When switching from the first main path to the first switching path, when the first power supply is chargeable, the control circuit forms the power supply path so that the first power supply and the second power supply are temporarily connected to the first circuit, and when switching from the second main path to the second switching path, when the second power supply is chargeable, the control circuit forms the power supply path so that the first power supply and the second power supply are temporarily connected to the second circuit. The power supply switching circuit according to claim 1 or 2, characterized in that.

9. When the control circuit switches from the first main path to the first switching path, if the first power supply is not chargeable, the power supply path is formed so that the first power supply and the second power supply are not connected to the first circuit. When switching from the second main path to the second switching path, if the second power supply is not chargeable, the power supply path is formed so that the first power supply and the second power supply are not connected to the second circuit. The power supply switching circuit according to claim 1 or 2, characterized in that.

10. The wiring connecting the first switching path and the first circuit is connected to a first capacitor (61). The power supply switching circuit according to claim 1 or 2, characterized in that the wiring connecting the second switching path and the second circuit is connected to a second capacitor (62).

11. When the control circuit switches the power supply path from the first main path to the first switching path, after setting the first circuit to a low load state, the first switching path is set to a conductive state. When switching the power supply path from the second main path to the second switching path, after setting the second circuit to a low load state, the second switching path is set to a conductive state. The power supply switching circuit according to claim 1 or 2, characterized in that.

12. When a problem occurs in the first main path or the second main path, the control circuit forms the power supply path so that power is supplied to the first circuit and the second circuit. The power supply switching circuit according to claim 3, characterized in that.

13. The power supply switching circuit according to claim 1 or 2, wherein the control circuit sets the other to a non-conductive state before setting one of the first switching path and the second switching path to a conductive state.

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