Backup power supply device and control method thereof

Abstract

A backup power supply device (30) is provided with a first switch (21), a second switch (22), a third switch (23), a fourth switch (24), an auxiliary power supply (25), and a control circuit (31), and the first switch (21) has a first diode (21b) provided in the direction in which current supplied from a main power supply (10) flows to the second switch (22) when the first switch (21) is turned off. A control circuit (31) performs: a first step (S30) in which a first switch (21) is turned off when a power supply for supplying a DC voltage to a load (12) is switched from a main power supply (10) to an auxiliary power supply (25); a second step (S31) of turning on the third switch (23) and the fourth switch (24) after the first step (S30); and a third step (S32) of turning off the second switch (22) after the second step (S31).

Description

Technical Field

[0001] The present disclosure relates to a backup power supply device and a control method thereof, and in particular to a backup power supply device that backs up the supply of a DC voltage from a main power supply to a load. Background Art

[0002] Conventionally, various power supply devices have been proposed as backup power supply devices for backing up the supply of a DC voltage from a main power supply to a load (for example, refer to Patent Document 1).

[0003] The power supply device of patent document 1 comprises: a first conductive circuit, which serves as a path for electric power between a first power supply unit and a load; a second conductive circuit, which is connected to the first conductive circuit and the second power supply unit; a first switch unit, which is provided in the first conductive circuit between a connection unit with the second conductive circuit and the first power supply unit, and switches between a non-conductive state in which bidirectional power is cut off and a conductive state in which power is supplied; a second switch unit, which is provided in the second conductive circuit between a connection unit and the second power supply unit, and switches between a non-conductive state in which bidirectional power is cut off and a conductive state in which power is supplied; and a control unit, which controls the switching actions of the first switch unit and the second switch unit respectively.

[0004] Thus, even if an abnormality occurs on the power supply side of either side, the current flowing into the path from the other power supply can be cut off. For example, even if a short circuit occurs in the second switch section, the current can be prevented from flowing from the first power supply section to the second power supply section by disconnecting the first switch section.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-216795 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, in the power supply device of Patent Document 1, when the power supply unit that supplies the DC voltage to the load is switched, the first switch unit and the second switch unit are both disconnected for a moment, so when the load side is grounded, the supply voltage to the load is temporarily cut off, and the supply voltage to the load may be greatly reduced to zero voltage, etc. Even if it is temporary, it is not uncommon for a load to suffer a fatal malfunction due to the supply voltage being reduced to zero voltage, and if such a situation occurs, the meaning of providing a backup power supply device disappears.

[0010] Therefore, an object of the present disclosure is to provide a backup power supply device and a control method thereof, which can suppress the supply voltage to the load from being cut off when switching a power supply that supplies a DC voltage to the load.

[0011] Means for solving problems

[0012] In order to achieve the above-mentioned purpose, a backup power supply device of one embodiment of the present invention backs up the supply of DC voltage from a main power supply to a load, and the backup power supply device comprises: a first switch, inserted in a path connecting the main power supply and the load, so as to turn on and off the supply of DC voltage from the main power supply to the load; a second switch, inserted in a path connecting the first switch and the load, so as to turn on and off the supply of DC voltage to the load via the first switch; an auxiliary power supply for supplying DC voltage to the load; a third switch, inserted in a path connecting the auxiliary power supply and the load, so as to turn on and off the supply of DC voltage from the auxiliary power supply to the load; a fourth switch, inserted in a path connecting the third switch and the load, so as to turn on and off the supply of DC voltage to the load via the third switch; and a control circuit, which controls the first switch, the second switch, the third switch and the fourth switch.

[0013] In order to achieve the above-mentioned purpose, a control method of a backup power supply device in one embodiment of the present invention is a control method of a backup power supply device for backing up the supply of DC voltage from a main power supply to a load, and the backup power supply device comprises: a first switch, inserted in a path connecting the main power supply and the load, so that the supply of DC voltage from the main power supply to the load is turned on and off; a second switch, inserted in a path connecting the first switch and the load, so that the supply of DC voltage to the load via the first switch is turned on and off; an auxiliary power supply for supplying DC voltage to the load; and a third switch, inserted in a path connecting the auxiliary power supply and the load, so that the supply of DC voltage from the auxiliary power supply to the load is turned on and off. The control method is configured to connect the third switch to the load and turn on and off the supply of the DC voltage to the load via the third switch, wherein the control method is configured to connect the third switch to the load and turn on and off the supply of the DC voltage to the load via the third switch. The ... fourth switch and turn on and off the supply of the DC voltage to the load via the third switch. The control method is configured to connect the third switch to the fourth switch and turn on and off the supply of the DC voltage to the load via the third switch.

[0014] Effects of the Invention

[0015] According to the present disclosure, there is provided a backup power supply device and a control method thereof, which can suppress the supply voltage to the load from being cut off when a power supply that supplies a DC voltage to a load is switched. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : is a circuit diagram showing the structure of a backup power supply device of a reference example.

[0017] Figure 2 This is a flowchart showing the operation of switching the power supply that supplies a DC voltage to a load in the backup power supply device of the reference example.

[0018] Figure 3 Yes means Figure 2 FIG. 1 is a timing chart showing the operating states of the components of the backup power supply device of the reference example during operation shown.

[0019] Figure 4 : is a circuit diagram showing the structure of the backup power supply device according to the embodiment.

[0020] Figure 5 This is a flowchart showing the operation of the backup power supply device according to the embodiment for switching the power supply that supplies a DC voltage to a load.

[0021] Figure 6 Yes means Figure 5 1 is a timing chart showing the operating states of the components of the backup power supply device according to the embodiment during operation shown.

[0022] Figure 7 It is a flowchart showing a control procedure of a modified example of the embodiment.

[0023] Figure 8 Yes means Figure 7 A timing chart showing the operating states of the components of the backup power supply device in the control procedure of the modified example shown.

[0024] Fig. 9 1 is a circuit diagram showing the structure of the backup power supply device of the first embodiment.

[0025] Fig.10 1 is a circuit diagram showing the structure of a backup power supply device according to a second embodiment.

[0026] Fig.11 It is a circuit diagram showing a configuration of a backup power supply device according to a modified example of the embodiment.

[0027] Fig.12 It is a circuit diagram showing the structure of a backup power supply device according to another modified example of the embodiment. DETAILED DESCRIPTION

[0028] (Insights Obtained by the Present Invention)

[0029] First, before describing the embodiments, the subject of the present disclosure will be described using the drawings as findings obtained by the present inventors.

[0030] Figure 1 1 is a circuit diagram showing the structure of a backup power supply device 20 of a reference example. In this figure, not only the backup power supply device 20 is illustrated, but also the main power supply 10 and the load 12 are illustrated. The main power supply 10 is a DC voltage source for supplying a DC voltage to the load 12, for example, a power supply (battery) mounted on a vehicle. The load 12 is an electrical load that receives a supply of a DC voltage, for example, an ECU (Electronic Control Unit) in a vehicle that receives a DC voltage from the main power supply 10 and the like and operates.

[0031] The backup power supply device 20 is a power supply that backs up the supply of DC voltage from the main power supply 10 to the load 12 , and includes a first switch 21 , a second switch 22 , a third switch 23 , a fourth switch 24 , an auxiliary power supply 25 , and a control circuit 26 .

[0032] Auxiliary power supply 25 is a DC voltage source for supplying a DC voltage to load 12 instead of main power supply 10 , and is, for example, a storage element charged by current supplied from main power supply 10 or a power supply circuit in which such a storage element is connected to a boost circuit.

[0033] The first switch 21 is a switch that is inserted into a path connecting the main power supply 10 and the load 12 and turns on and off the supply of a DC voltage from the main power supply 10 to the load 12. The first switch 21 is composed of a first MOSFET 21a and a first diode 21b. The first diode 21b is a parasitic diode of the first MOSFET 21a and is arranged in a direction in which the current supplied from the main power supply 10 flows toward the second switch 22.

[0034] The second switch 22 is a switch that is inserted into a path connecting the first switch 21 and the load 12 and turns on and off the supply of a DC voltage to the load 12 via the first switch 21. The second switch 22 is composed of a second MOSFET 22a and a second diode 22b. The second diode 22b is a parasitic diode of the second MOSFET 22a and is arranged in a direction that allows current to flow from the load 12 to the first switch 21.

[0035] The third switch 23 is a switch that is inserted into a path connecting the auxiliary power supply 25 and the load 12 and turns on and off the supply of a DC voltage from the auxiliary power supply 25 to the load 12. The third switch 23 is composed of a third MOSFET 23a and a third diode 23b. The third diode 23b is a parasitic diode of the third MOSFET 23a and is arranged in a direction in which the current supplied from the auxiliary power supply 25 flows toward the fourth switch 24.

[0036] The fourth switch 24 is a switch inserted into the path connecting the third switch 23 and the load 12 and turns on and off the supply of the DC voltage to the load 12 via the third switch 23. The fourth switch 24 is composed of a fourth MOSFET 24a and a fourth diode 24b. The fourth diode 24b is a parasitic diode of the fourth MOSFET 24a and is arranged in a direction so that the current flows from the load 12 to the third switch 23.

[0037] In addition, in this reference example, the first MOSFET 21 a , the second MOSFET 22 a , the third MOSFET 23 a , and the fourth MOSFET 24 a are all N-channel MOS transistors.

[0038] The control circuit 26 is a circuit that controls the first switch 21 , the second switch 22 , the third switch 23 , and the fourth switch 24 , and is composed of, for example, a memory that stores a program, a processor that executes the program, an input / output circuit, and the like.

[0039] Figure 2 Yes means Figure 1 1 is a flowchart of the operation of switching the power supply for supplying a DC voltage to the load 12 (i.e., the control method of the backup power supply 20) according to the reference example shown in FIG. Figure 2 (a) is a flowchart showing a case where the power supply for supplying a DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25. Such a case corresponds to a case where a power failure occurs in the main power supply 10, such as a battery exhaustion. Figure 2 (b) is a flowchart showing a case where the power supply for supplying a DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10. This case corresponds to, for example, a case where the main power supply 10 recovers after a power failure.

[0040] like Figure 2 As shown in (a), when the power supply for supplying a DC voltage to a load 12 is switched from a main power supply 10 to an auxiliary power supply 25, with the first switch 21 and the second switch 22 being turned on and the third switch 23 and the fourth switch 24 being turned off, the control circuit 26 first changes the first switch 21 and the second switch 22 from being turned on to being turned off at the same time (S10), and then changes the third switch 23 and the fourth switch 24 from being turned off to being turned on at the same time (S11).

[0041] like Figure 2As shown in (b), when the power supply for supplying a DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10, with the first switch 21 and the second switch 22 being off and the third switch 23 and the fourth switch 24 being on, the control circuit 26 first changes the third switch 23 and the fourth switch 24 from being on to being off at the same time (S20), and then changes the first switch 21 and the second switch 22 from being off to being on at the same time (S21).

[0042] Figure 3 Yes means Figure 2 The timing diagram of the operation state of each component of the backup power supply device 20 of the reference example during operation shown in FIG. Figure 3 (a) represents the output voltage of the main power supply 10 ("power supply voltage"), Figure 3 (b) represents the voltage supplied to the load 12 ("load voltage"), Figure 3 (c) to (f) respectively represent the on / off states of the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24.

[0043] exist Figure 3 "t0" is the time point when the main power supply 10 begins to fail, "S10", "S11", "S20" and "S21" are the execution times of Figure 2 Step S10, step S11, Figure 2 The time points of step S20 and step S21 in (b) of FIG. 2 . In addition, immediately before the time point S20, the main power supply 10 recovers from the power failure.

[0044] like Figure 3 As shown, from time point t0, due to the power failure of the main power supply 10, the "power supply voltage" and the "load voltage" begin to drop. At time point S10, in order to switch the power supply for supplying DC voltage to the load 12 from the main power supply 10 to the auxiliary power supply 25, first, the first switch 21 and the second switch 22 are simultaneously changed from on to off, and then, at time point S11, the third switch 23 and the fourth switch 24 are simultaneously changed from off to on. As a result, the power supply for supplying DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25.

[0045] Here, when focusing on the period from time point S10 to time point S11 (that is, from time point S10 to immediately before time point S11), during this period, the four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) are all in the off state, so the voltage supply to the load 12 is cut off. In the event of load side grounding (that is, the load 12 is abnormally in a low impedance state), etc., the supply voltage to the load 12 may be significantly reduced to zero voltage, etc., depending on the extent. Figure 3 The cross-hatching between the time point S10 and the time point S11 of the "load voltage" shown in (b) indicates this possibility.

[0046] In addition, at time point S20, the main power supply 10 that has experienced a power failure is restored, and in order to switch the power supply that supplies the DC voltage to the load 12 from the auxiliary power supply 25 to the main power supply 10, the third switch 23 and the fourth switch 24 are simultaneously changed from on to off, and then at time point S21, the first switch 21 and the second switch 22 are simultaneously changed from off to on. As a result, the power supply that supplies the DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10.

[0047] Here, when focusing on the period from time point S20 to time point S21 (that is, from time point S20 to immediately before time point S21), during this period, the four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) are all in the off state, so the voltage supply to the load 12 is cut off. In the event of load side grounding (that is, the load 12 is abnormally in a low impedance state), etc., the supply voltage to the load 12 may be significantly reduced to zero voltage, etc., depending on the extent. Figure 3 The cross-hatching between the time point S20 and the time point S21 of the "load voltage" shown in (b) indicates this possibility.

[0048] Thus, when the backup power supply device 20 of the reference example switches the power supply for supplying a DC voltage to the load 12, the four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) are all disconnected at a moment, so that when a load side ground fault occurs, the supply voltage to the load 12 is temporarily cut off, and the supply voltage to the load 12 may be greatly reduced to zero voltage, etc. Even if it is temporary, it is not uncommon for a load to suffer a fatal adverse condition due to the supply voltage being reduced to zero voltage. If such a situation occurs, the meaning of providing a backup power supply device disappears.

[0049] Therefore, the inventors of the present invention have conceived of the following backup power supply device: when switching the power supply that supplies a DC voltage to the load 12, the first switch 21 is effectively utilized to have a first diode 21b arranged in a direction that causes the current supplied from the main power supply 10 to flow toward the load 12, and a control step is performed to avoid all four switches (the first switch 21, the second switch 22, the third switch 23 and the fourth switch 24) from being disconnected at the same time, thereby preventing the supply voltage to the load 12 from being cut off when the power supply is switched.

[0050] (Implementation Method)

[0051] Hereinafter, the embodiments of the present disclosure are described in detail using the accompanying drawings. In addition, the embodiments described below all represent a specific example of the present disclosure. The numerical values, shapes, materials, constituent elements, configuration positions of constituent elements, connection methods, steps, order of steps, etc. shown in the following embodiments are examples and are not intended to limit the present disclosure. In addition, the figures are not necessarily strictly illustrated figures. In each figure, the same figure mark is marked for substantially the same structure, and repeated descriptions are omitted or simplified. In addition, "A is connected to B" means that A is electrically connected to B, which includes not only the case where A is directly connected to B, but also the case where A is indirectly connected to B in a state where other circuit elements are interposed between A and B.

[0052] Figure 4 1 is a circuit diagram showing the structure of the backup power supply device 30 according to the embodiment. Figure 1 Likewise, a main power source 10 and a load 12 are also shown.

[0053] The backup power supply device 30 is a power supply for backing up the supply of DC voltage from the main power supply 10 to the load 12, and includes a first switch 21, a second switch 22, a third switch 23, a fourth switch 24, an auxiliary power supply 25, and a control circuit 31. Figure 1 The configuration that is different from the backup power supply device 20 of the reference example shown is the control circuit 31. The following description will focus on the differences from the backup power supply device 20 of the reference example.

[0054] The control circuit 31 is a circuit for controlling the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24, and is composed of, for example, a memory storing a program, a processor executing the program, and an input-output circuit, etc. The control circuit 31 is different from the control circuit 26 provided in the backup power supply device 20 of the reference example. When switching the power supply supplying the DC voltage to the load 12, the control circuit 31 effectively utilizes the fact that the first switch 21 has a first diode 21b provided in a direction that causes the current supplied from the main power supply 10 to flow toward the load 12, and performs a control step to prevent all four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) from being turned off at the same time, thereby preventing the supply voltage to the load 12 from being cut off when the power supply is switched.

[0055] In addition, the backup power supply device 30 has four switches (a first switch 21, a second switch 22, a third switch 23, and a fourth switch 24) similar to patent document 1, so that even if an abnormality such as a short circuit occurs in either the main power supply 10 or the auxiliary power supply 25, the current flowing into the path from the other power supply can be cut off.

[0056] Figure 5 Yes means Figure 4 The flowchart of the operation of the backup power supply device 30 of the embodiment shown in the figure switches the power supply for supplying the DC voltage to the load 12 (that is, the control method of the backup power supply device 30). Figure 5 (a) is a flowchart showing a case where the power supply for supplying a DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25. Such a case corresponds to a case where a power failure occurs in the main power supply 10, such as a battery exhaustion, and is similar to the case of the backup power supply device 20 of the reference example. Figure 2 In addition, Figure 5 (b) is a flowchart showing a case where the power supply for supplying DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10. Such a case corresponds to, for example, a case where the main power supply 10 is restored after a power failure, and is similar to the case of the backup power supply device 20 of the reference example. Figure 2 corresponds to (b).

[0057] like Figure 5 As shown in (a), when the power supply for supplying DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, the control circuit 31 first turns the first switch 21 from on to off (S30) while the first switch 21 and the second switch 22 are on and the third switch 23 and the fourth switch 24 are off, and then turns the second switch 22 from on to off (S32) after turning the third switch 23 and the fourth switch 24 from off to on at the same time (S31). Figure 2 Compared with (a), Figure 2 Step S10 in (a) is equivalent to separating into Figure 5 The process of step S30 and step S32 of (a).

[0058] like Figure 5 As shown in (b), when the power supply for supplying DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10, the control circuit 31 first changes the second switch 22 from off to on (S40) while the first switch 21 and the second switch 22 are off and the third switch 23 and the fourth switch 24 are on. Then, after changing the third switch 23 and the fourth switch 24 from on to off at the same time (S41), the control circuit 31 changes the first switch 21 from off to on (S42). Figure 2 Compared with (b), Figure 2 Step S20 in (b) is equivalent to separating into Figure 5 The process of step S40 and step S42 of (b).

[0059] Figure 6 Yes means Figure 5 1 is a timing chart showing the operating states of the components of the backup power supply device 30 according to the embodiment during operation shown. Figure 6 (a) to (f) represent Figure 3 Timing of the same parts in (a) to (f).

[0060] exist Figure 6 In the timing of, "t0" is the time point when the main power supply 10 begins to fail, "S30" to "S32", and "S40" to "S42" are respectively executed. Figure 5 Steps S30 to S32 in (a), Figure 5 The time point of steps S40 to S42 in (b) of FIG. 2 is as follows. In addition, immediately before the time point S40, the main power supply 10 recovers from the power failure.

[0061] like Figure 6 As shown, from time point t0, due to the power failure of the main power supply 10, the "power supply voltage" and the "load voltage" begin to drop. At time point S30, in order to switch the power supply for supplying DC voltage to the load 12 from the main power supply 10 to the auxiliary power supply 25, first, the first switch 21 changes from on to off, and then, at time point S31, the third switch 23 and the fourth switch 24 change from off to on at the same time, and then, at time point S32, the second switch 22 changes from on to off. As a result, the power supply for supplying DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25.

[0062] Here, when focusing on the period from time point S30 to time point S31 (i.e., from time point S30 to immediately before time point S31), during this period, the first switch 21, the third switch 23, and the fourth switch 24 are turned off, but since the second switch 22 is kept on, the state of supplying current from the main power supply 10 to the load 12 via the first diode 21b of the first switch 21 and the second switch 22 is maintained. However, a voltage drop occurs in the first diode 21b. As a result, as Figure 6 As shown in the “load voltage” from time point S30 to time point S31, the voltage drop of the “load voltage” is an amount corresponding to the voltage drop in the first diode 21b, but since the current supply from the main power supply 10 is maintained, even if the load side is grounded (that is, the load 12 becomes abnormally in a low impedance state), etc., the voltage can be suppressed from dropping further significantly.

[0063] In addition, at time point S31, the third switch 23 and the fourth switch 24 simultaneously change from off to on, thereby starting to supply voltage from the auxiliary power supply 25 to the load 12, and the "load voltage" rises. However, since the second switch 22 is maintained on, the first diode 21b of the first switch 21 is in a reverse biased state, preventing current from flowing from the auxiliary power supply 25 to the main power supply 10.

[0064] Furthermore, at the time point S32, the second switch 22 changes from being on to being off. However, in the state immediately before, the current does not flow through the second switch 22, so that the “load voltage” does not particularly fluctuate.

[0065] In addition, at time point S40, the main power supply 10 that has experienced power failure is restored. In order to switch the power supply that supplies the DC voltage to the load 12 from the auxiliary power supply 25 to the main power supply 10, first, the second switch 22 is changed from off to on, then at time point S41, the third switch 23 and the fourth switch 24 are changed from on to off at the same time, and then at time point S42, the first switch 21 is changed from off to on. As a result, the power supply that supplies the DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10.

[0066] Here, at time point S40, only the second switch 22 of the first switch 21 and the second switch 22 changes from off to on, but since the third switch 23 and the fourth switch 24 are kept on, the voltage supply from the auxiliary power supply 25 to the load 12 is maintained and a reverse bias is applied to the first diode 21b of the off first switch 21. This state is the same as that at time point S32, and no particular change in the "load voltage" occurs.

[0067] In addition, when focusing on the period from time point S41 to time point S42 (that is, from time point S41 to immediately before time point S42), during this period, while maintaining the on state of the second switch 22, the third switch 23 and the fourth switch 24 are simultaneously turned from on to off, thereby supplying current from the main power supply 10 to the load 12 via the first diode 21b of the disconnected first switch 21 and the second switch 22. However, a voltage drop occurs in the first diode 21b. As a result, as Figure 6 As shown in the "load voltage" from time point S41 to time point S42, the "load voltage" rises to a voltage that is reduced from the output voltage of the main power supply 10 by an amount corresponding to the voltage drop in the first diode 21b, maintaining the current supply from the main power supply 10. Therefore, even if a load side grounding occurs (i.e., the load 12 becomes abnormally in a low impedance state), the voltage can be suppressed from further significantly decreasing.

[0068] Furthermore, at time point S42 , the first switch 21 changes from off to on, so that no voltage drop occurs in the first diode 21 b of the first switch 21 , and the voltage supply from the main power supply 10 to the load 12 via the first switch 21 and the second switch 22 is restarted.

[0069] As described above, the backup power supply device 30 of the embodiment effectively utilizes the first switch 21 having a first diode 21b arranged in the direction of causing the current supplied from the main power supply 10 to flow toward the load 12 when switching the power supply that supplies the DC voltage to the load 12, and performs control steps to avoid all four switches (the first switch 21, the second switch 22, the third switch 23 and the fourth switch 24) from being disconnected at the same time, thereby preventing the supply voltage to the load 12 from being cut off when the power supply is switched.

[0070] In addition, in the above-mentioned embodiment, when switching the power supply for supplying the DC voltage to the load 12, the third switch 23 and the fourth switch 24 are simultaneously changed from off to on or from on to off, but may be changed from off to on or from on to off in sequence. Hereinafter, the control steps in this case will be described as the control steps of a modified example of the embodiment.

[0071] Figure 7 1 is a flowchart showing a control procedure of a modified example of the embodiment (ie, a control method of the backup power supply device 30). Figure 7 (a) is a flowchart showing a control procedure of a modified example in which the power source supplying a DC voltage to the load 12 is switched from the main power source 10 to the auxiliary power source 25 . Figure 7 (b) is a flowchart showing a control procedure of a modified example in which the power source supplying the DC voltage to the load 12 is switched from the auxiliary power source 25 to the main power source 10 .

[0072] like Figure 7 As shown in (a) of FIG. 1 , when the power supply for supplying a DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, the control steps of the modified example are equivalent to switching the control steps of the embodiment Figure 5 Step S31 (making the third switch 23 and the fourth switch 24 switch from off to on at the same time) in the flowchart shown in (a) is separated into two steps S31a (making the fourth switch 24 switch from off to on) and step S31b (making the third switch 23 switch from off to on) which are executed sequentially.

[0073] In addition, if Figure 7 As shown in (b) of FIG. 1 , when the power supply for supplying DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10, the control steps of the modified example are equivalent to switching the control steps of the embodiment of FIG. Figure 5 Step S41 (making the third switch 23 and the fourth switch 24 turn from on to off at the same time) in the flowchart shown in (b) is separated into two steps S41a (making the third switch 23 turn from on to off) and step S41b (making the fourth switch 24 turn from on to off) which are executed sequentially.

[0074] Figure 8Yes means Figure 7 The timing chart of the operation state of each component of the backup power supply device 30 in the control procedure of the modified example shown. Figure 8 (a) to (f) represent Figure 3 The timing of the same parts (a) to (f). Figure 8 In the timing of, "t0" is the time point when the main power supply 10 begins to fail, "S30" to "S32", and "S40" to "S42" are respectively executed. Figure 7 Steps S30 to S32 in (a), Figure 7 The time point of steps S40 to S42 in (b) of FIG. 2 is as follows. In addition, immediately before the time point S40, the main power supply 10 recovers from the power failure.

[0075] At time point S31a, only the fourth switch 24 of the third switch 23 and the fourth switch 24 changes from off to on, so that the current supply from the auxiliary power supply 25 to the load 12 via the third diode 23b of the third switch 23 and the fourth switch 24 starts. Figure 8 As shown in the “load voltage” from the time point S31a to the time point S31b, the “load voltage” is a voltage which is higher than the immediately previous voltage and is lower than the output voltage of the auxiliary power supply 25 by an amount corresponding to the voltage drop in the third diode 23b.

[0076] Afterwards, at time point S31b, the third switch 23 also changes from off to on, following the fourth switch 24, thus becoming the same as in the embodiment. Figure 6 The same state as at time point S31.

[0077] In addition, at time point S41a, only the third switch 23 of the third switch 23 and the fourth switch 24 changes from on to off, so that the load 12 is supplied with a higher voltage of a voltage obtained by reducing the output voltage of the auxiliary power supply 25 by an amount corresponding to the voltage drop in the third diode 23b, and a voltage obtained by reducing the output voltage of the main power supply 10 by an amount corresponding to the voltage drop in the first diode 21b.

[0078] Afterwards, at time point S41b, the third switch 23 and the fourth switch 24 also change from being on to being off, thus becoming the same as in the embodiment. Figure 6 The same state as at time point S41.

[0079] Here, at time point S31a to time point S31b and time point S41a to time point S41b, the first switch 21 close to the main power supply 10 is disconnected, the third switch 23 close to the auxiliary power supply 25 is disconnected, and the second switch 22 and the fourth switch 24 close to the load 12 are turned on, so that the load 12 is supplied with a higher voltage of a voltage obtained by reducing the output voltage of the main power supply 10 by an amount corresponding to the voltage drop in the first diode 21b and a voltage obtained by reducing the output voltage of the auxiliary power supply 25 by an amount corresponding to the voltage drop in the third diode 23b. Therefore, even if the output voltage of the main power supply 10 changes drastically and decreases significantly, it is possible to ensure that the load 12 does not fall below the voltage supplied from the auxiliary power supply 25.

[0080] Next, two specific implementation examples of the auxiliary power supply 25 included in the backup power supply device 30 of the above-described embodiment will be described.

[0081] Fig. 9 The backup power supply device 30 of the above embodiment includes the auxiliary power supply 25 including a step-down circuit 25a, a storage element 25b, and a step-up circuit 25c.

[0082] The step-down circuit 25a is a circuit that steps down the DC voltage supplied from the main power supply 10 to charge the storage element 25b. For example, it is a step-down DC / DC converter composed of switching elements such as MOSFET, inductors, diodes and capacitors, and operates under the control of the control circuit 31.

[0083] The power storage element 25b is a capacitor such as an electric double layer capacitor.

[0084] The boost circuit 25c is a circuit that boosts the DC voltage output from the storage element 25b and supplies the boosted DC voltage to the load 12 via the third switch 23 and the fourth switch 24. For example, it is a boost type DC / DC converter composed of switching elements such as MOSFET, inductors, diodes and capacitors, and operates under the control of the control circuit 31.

[0085] According to the backup power supply device 30a of the first implementation example, the auxiliary power supply 25 has the storage element 25b charged from the main power supply 10, so it is not necessary to have a power generation function. In addition, the DC voltage output from the storage element 25b is boosted by the boost circuit 25c and supplied to the load 12, so the auxiliary power supply 25 can be realized by the storage element 25b, and the storage element 25b can maintain a lower voltage than the main power supply 10.

[0086] Fig.102 is a circuit diagram showing a configuration of a backup power supply device 30b of a second implementation example. As the auxiliary power supply 25 provided in the backup power supply device 30 of the above embodiment, the backup power supply device 30b includes the auxiliary power supply 25 including a step-up / step-down circuit 25d and a storage element 25b.

[0087] The step-up / down circuit 25d is a circuit having a function of stepping down the DC voltage supplied from the main power supply 10 to charge the storage element 25b, and a function of stepping up the DC voltage output from the storage element 25b and supplying the stepped-up DC voltage to the load 12 via the third switch 23 and the fourth switch 24. For example, the step-up / down DC / DC converter is composed of a switching element such as a MOSFET, an inductor, a diode, and a capacitor, and operates under the control of the control circuit 31. For example, under the control of the control circuit 31, when the main power supply 10 supplies a DC voltage to the load 12 and the voltage of the storage element 25b is lower than a predetermined value, the step-up / down circuit 25d steps down the DC voltage supplied from the main power supply 10 to charge the storage element 25b. On the other hand, when the power supply supplying the DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, the step-up / down circuit 25d steps up the DC voltage output from the storage element 25b and supplies the stepped-up DC voltage to the load 12 via the third switch 23 and the fourth switch 24.

[0088] According to the backup power supply device 30b of the second implementation example, compared with the backup power supply device 30a of the first implementation example, the same function as the backup power supply device 30a of the first implementation example can be achieved by using the auxiliary power supply 25 with a smaller circuit size.

[0089] Furthermore, in the above-mentioned embodiments, variations and implementation examples, the first MOSFET 21 a , the second MOSFET 22 a , the third MOSFET 23 a and the fourth MOSFET 24 a are all N-channel MOS transistors, but they may be replaced by P-channel MOS transistors.

[0090] Fig.11 1 is a circuit diagram showing the configuration of a backup power supply device 30c according to a modified example of the embodiment. Figure 4 The backup power supply device 30 of the illustrated embodiment has a structure in which the four N-channel MOS transistors (first MOSFET 21a, second MOSFET 22a, third MOSFET 23a and fourth MOSFET 24a) of the backup power supply device 30 are replaced with P-channel MOS transistors (first MOSFET 21c, second MOSFET 22c, third MOSFET 23c and fourth MOSFET 24c).

[0091] The backup power supply device 30c of such a modified example operates in the same control procedure as the backup power supply devices of the embodiment, modified example, and implementation example. However, the backup power supply device 30c composed of P-channel MOS transistors does not require a voltage higher than the voltage of the main power supply 10 as a bias voltage to be supplied to the gate of each transistor, compared with the backup power supply device composed of N-channel MOS transistors, and thus has the advantage of simplifying the control circuit 31, etc.

[0092] As described above, the backup power supply device 30 of the embodiment is a power supply for backing up the supply of DC voltage from the main power supply 10 to the load 12, and includes: a first switch 21, which is inserted into the path connecting the main power supply 10 and the load 12, so as to turn on and off the supply of DC voltage from the main power supply 10 to the load 12; a second switch 22, which is inserted into the path connecting the first switch 21 and the load 12, so as to turn on and off the supply of DC voltage to the load 12 via the first switch 21; an auxiliary power supply 25 for supplying DC voltage to the load 12; a third switch 23, which is inserted into the path connecting the auxiliary power supply 25 and the load 12, so as to turn on and off the supply of DC voltage from the auxiliary power supply 25 to the load 12; a fourth switch 24, which is inserted into the path connecting the third switch 23 and the load 12, so as to turn on and off the supply of DC voltage to the load 12 via the third switch 23; and a control circuit 31, which controls the first switch 21, the second switch 22, the third switch 23 and the fourth switch 24.

[0093] Thus, when the control circuit 31 switches the power supply for supplying a DC voltage to the load 12 from the main power supply 10 to the auxiliary power supply 25, the first switch 21 and the second switch 22 are turned on and the third switch 23 and the fourth switch 24 are turned off. The control circuit 31 can execute a first step S30 of turning off the first switch 21, a second step S31 of turning on the third switch 23 and the fourth switch 24 after the first step S30, and a third step S32 of turning off the second switch 22 after the second step S31.

[0094] Therefore, when the power supply for supplying a DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, the first switch 21 is effectively utilized to have a first diode 21b arranged in a direction in which the current supplied from the main power supply 10 flows toward the load 12, and a control step is performed to prevent all four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) from being disconnected at the same time, thereby preventing the supply voltage to the load 12 from being cut off when the power supply is switched.

[0095] Here, the third switch 23 may include a third diode 23b, which is provided in a direction that allows the current supplied from the auxiliary power supply 25 to flow toward the fourth switch 24 when the third switch 23 is turned off. In the second step S31, after the fourth switch 24 is turned on (step S31a), the third switch 23 is turned on (step S31b). Thus, from time point S31a to time point S31b, a voltage that is a higher voltage of a voltage obtained by reducing the output voltage of the main power supply 10 by an amount corresponding to the voltage drop in the first diode 21b and a voltage obtained by reducing the output voltage of the auxiliary power supply 25 by an amount corresponding to the voltage drop in the third diode 23b is supplied to the load 12. Therefore, even when the output voltage of the main power supply 10 changes drastically and decreases significantly, it is possible to ensure that the load 12 does not fall below the voltage supplied from the auxiliary power supply 25.

[0096] In addition, the control circuit 31 also executes: a fourth step S40, in which, when the power supply for supplying DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10, the second switch 22 is turned on while the first switch 21 and the second switch 22 are turned off and the third switch 23 and the fourth switch 24 are turned on; a fifth step S41, in which, after the fourth step S40, the third switch 23 and the fourth switch 24 are turned off; and a sixth step S42, in which, after the fifth step S41, the first switch 21 is turned on.

[0097] Therefore, when the power supply for supplying a DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10, the first switch 21 is effectively utilized to have a first diode 21b arranged in a direction in which the current supplied from the main power supply 10 flows toward the load 12, and a control step is performed to prevent all four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) from being disconnected at the same time, thereby preventing the supply voltage to the load 12 from being cut off when the power supply is switched.

[0098] Here, the third switch 23 may include a third diode 23b, which is provided in a direction that allows the current supplied from the auxiliary power supply 25 to flow to the fourth switch 24 when the third switch 23 is turned off. In the fifth step S41, after the third switch 23 is turned off (step S41a), the fourth switch 24 is turned off (step S41b). Thus, from time point S41a to time point S41b, a voltage that is a higher voltage of a voltage obtained by reducing the output voltage of the main power supply 10 by an amount corresponding to the voltage drop in the first diode 21b and a voltage obtained by reducing the output voltage of the auxiliary power supply 25 by an amount corresponding to the voltage drop in the third diode 23b is supplied to the load 12. Therefore, even when the output voltage of the main power supply 10 changes drastically and decreases significantly, it is possible to ensure that the load 12 does not fall below the voltage supplied from the auxiliary power supply 25.

[0099] In addition, the first switch 21 may include a first diode 21b, which is provided in a direction in which the current supplied from the main power supply 10 flows toward the second switch 22 when the first switch 21 is disconnected; the second switch 22 may include a second diode 22b, which is provided in a direction in which the current flows from the load 12 toward the first switch 21 when the second switch 22 is disconnected; the third switch 23 may include a third diode 23b, which is provided in a direction in which the current supplied from the auxiliary power supply 25 flows toward the fourth switch 24 when the third switch 23 is disconnected; and the fourth switch 24 may include a fourth diode 24b, which is provided in a direction in which the current flows from the load 12 toward the third switch 23 when the fourth switch 24 is disconnected. As a result, the directions of current flow of the first diode 21b of the first switch 21 and the second diode 22b of the second switch 22 are opposite, and the directions of current flow of the third diode 23b of the third switch 23 and the fourth diode 24b of the fourth switch 24 are opposite, so the current flowing in both directions can be cut off by the first switch 21 and the second switch 22.

[0100] Alternatively, the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24 may be MOSFETs, and the first diode 21b, the second diode 22b, the third diode 23b, and the fourth diode 24b may be parasitic diodes of the MOSFETs. Thus, the backup power supply device 30 and the like can be realized with a small number of components.

[0101] In addition, the auxiliary power supply 25 may also include a storage element 25b that is charged by the current supplied from the main power supply 10. Furthermore, the auxiliary power supply 25 may also include: a step-down circuit 25a that steps down the DC voltage supplied from the main power supply 10 to charge the storage element 25b; and a step-up circuit 25c that steps up the DC voltage output from the storage element 25b and supplies the stepped-up DC voltage to the load 12 via the third switch 23 and the fourth switch 24.

[0102] Thus, the auxiliary power supply 25 does not need to have a power generation function because it has the storage element 25b charged from the main power supply 10. In addition, the DC voltage output from the storage element 25b is boosted by the boost circuit 25c and supplied to the load 12, so the auxiliary power supply 25 can be realized by the storage element 25b, which can maintain a lower voltage than the main power supply 10.

[0103] In addition, the control method of the backup power supply device 30 of the embodiment is a control method of the backup power supply device 30 for backing up the supply of DC voltage from the main power supply 10 to the load 12, and the backup power supply device 30 includes: a first switch 21, which is inserted into the path connecting the main power supply 10 and the load 12, so that the supply of DC voltage from the main power supply 10 to the load 12 is turned on and off; a second switch 22, which is inserted into the path connecting the first switch 21 and the load 12, so that the supply of DC voltage to the load 12 via the first switch 21 is turned on and off; an auxiliary power supply 25, which is used to supply DC voltage to the load 12; a third switch 23, which is inserted into the path connecting the auxiliary power supply 25 and the load 12, so that the DC voltage from the auxiliary power supply 25 to the load 12 is turned on and off. The supply of DC voltage is turned on and off; and the fourth switch 24 is inserted into the path connecting the third switch 23 and the load 12, so that the supply of DC voltage to the load 12 via the third switch 23 is turned on and off. The control method of the backup power supply device 30, when the power supply for supplying DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, includes: a first step S30 of turning off the first switch 21; a second step S31 of turning on the third switch 23 and the fourth switch 24 after the first step S30; and a third step S32 of turning off the second switch 22 after the second step S31.

[0104] Therefore, when the power supply for supplying a DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, the first switch 21 is effectively utilized to have a first diode 21b arranged in a direction in which the current supplied from the main power supply 10 flows toward the load 12, and a control step is performed to prevent all four switches (the first switch 21, the second switch 22, the third switch 23, and the fourth switch 24) from being disconnected at the same time, thereby preventing the supply voltage to the load 12 from being cut off when the power supply is switched.

[0105] In addition, in the above-mentioned embodiments, variations and implementation examples, the cathodes of the first diode 21b and the second diode 22b are connected to each other (i.e., they are configured to face inwardly toward each other), and the cathodes of the third diode 23b and the fourth diode 24b are connected to each other (i.e., they are configured to face inwardly toward each other), but these diodes can also be connected in the opposite direction (i.e., facing outwardly toward each other).

[0106] Fig.12 1 is a circuit diagram showing the structure of a backup power supply device 30d according to another modified example of the embodiment. Figure 4 The backup power supply device 30 of the illustrated embodiment has a configuration in which the directions of the four diodes (the first diode 21b, the second diode 22b, the third diode 23b, and the fourth diode 24b) included in the backup power supply device 30 are respectively reversed.

[0107] In such a backup power supply device 30d, in the control step of switching the main power supply 10 and the auxiliary power supply 25, compared with the implementation method, the order of turning on / off the first switch 21 and the second switch 22 is swapped, and the order of turning on / off the third switch 23 and the fourth switch 24 is swapped.

[0108] For example, when the power supply for supplying a DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25 ( Figure 7 (a)), in step S30, instead of changing the first switch 21 from on to off, the second switch 22 is changed from on to off. In addition, in step S31a, instead of changing the fourth switch 24 from off to on, the third switch 23 is changed from off to on. In addition, in step S31b, instead of changing the third switch 23 from off to on, the fourth switch 24 is changed from off to on. And, in step S32, instead of changing the second switch 22 from on to off, the first switch 21 is changed from on to off.

[0109] In addition, when the power supply for supplying a DC voltage to the load 12 is switched from the auxiliary power supply 25 to the main power supply 10 ( Figure 7(b)), in step S40, instead of changing the second switch 22 from off to on, the first switch 21 is changed from off to on. In addition, in step S41a, instead of changing the third switch 23 from on to off, the fourth switch 24 is changed from on to off. In addition, in step S41b, instead of changing the fourth switch 24 from on to off, the third switch 23 is changed from on to off. And, in step S42, instead of changing the first switch 21 from off to on, the second switch 22 is changed from off to on.

[0110] Such a control procedure can achieve the effect of preventing the supply voltage to the load 12 from being cut off when the power source is switched, similarly to the embodiment.

[0111] In addition, according to the backup power supply device 30d having such a structure, by respectively turning on and off the first switch 21, the second switch 22, the third switch 23 and the fourth switch 24, it is possible to choose whether to apply the voltage value of the main power supply 10 and the auxiliary power supply 25 to each switch or not to apply the voltage value of the main power supply 10 and the auxiliary power supply 25. Therefore, in the event that any switch fails, by monitoring the voltage at both ends of the switch, it is possible to confirm whether there is a fault based on the voltage difference at both ends of the switch.

[0112] In the backup power supply device 30 of the above-mentioned embodiment, for example, when confirming whether the second switch 22 has a short-circuit fault without cutting off the voltage of the load 12, the voltage across the second switch 22 is confirmed in a state where the third switch 23 and the fourth switch 24 are turned on and power is supplied from the auxiliary power supply 25 to the load 12. However, even if the first switch 21 is turned off, since the voltage of the main power supply 10 is supplied to the second switch 22 via the first diode 21b, when the voltage values ​​of the main power supply 10 and the auxiliary power supply 25 are close, it is impossible to accurately determine whether the second switch 22 has a short-circuit fault.

[0113] In this regard, according to the backup power supply device 30d of the modified example, when confirming whether the second switch 22 has a short-circuit fault without cutting off the voltage of the load 12, if the first switch 21 is disconnected while the third switch 23 and the fourth switch 24 are turned on and power is supplied from the auxiliary power supply 25 to the load 12, the voltage of the main power supply 10 is not applied to the second switch 22 but only the voltage of the auxiliary power supply 25 is applied to the second switch 22, so a voltage difference is generated at both ends of the second switch 22, and the short-circuit fault of the second switch 22 can be accurately determined.

[0114] As described above, when both the backup power supply device 30 of the embodiment in which the diodes are connected inwardly and the backup power supply device 30d of the modification in which the diodes are connected outwardly are represented, the backup power supply device of the present disclosure can be said to have the following features.

[0115] That is, the backup power supply device of the present disclosure is a power supply for backing up the supply of DC voltage from the main power supply 10 to the load 12, and comprises: a first switch 21, which is inserted in the path connecting the main power supply 10 and the load 12, so as to turn on and off the supply of DC voltage from the main power supply 10 to the load 12; a second switch 22, which is inserted in the path connecting the first switch 21 and the load 12, so as to turn on and off the supply of DC voltage to the load 12 via the first switch 21; an auxiliary power supply 25, which is used to supply DC voltage to the load 12; a third switch 23, which is inserted in the path connecting the auxiliary power supply 25 and the load 12, so as to turn on and off the supply of DC voltage from the auxiliary power supply 25 to the load 12; a fourth switch 24, which is inserted in the path connecting the third switch 23 and the load 12, so as to turn on and off the supply of DC voltage from the auxiliary power supply 25 to the load 12; The supply of DC voltage to the load 12 via the third switch 23 is turned on and off; and the control circuit 31 controls the first switch 21, the second switch 22, the third switch 23 and the fourth switch 24. When the power supply for supplying DC voltage to the load 12 is switched from the main power supply 10 to the auxiliary power supply 25, the control circuit 31, when the first switch 21 and the second switch 22 are turned on and the third switch 23 and the fourth switch 24 are turned off, performs: a first step S30, turning off one of the first switch 21 and the second switch 22; a second step S31, after the first step S30, turning on the third switch 23 and the fourth switch 24; and a third step S32, after the second step S31, turning off the other of the first switch 21 and the second switch 22.

[0116] In addition, when the control circuit 31 switches the power supply for supplying DC voltage to the load 12 from the auxiliary power supply 25 to the main power supply 10, with the first switch 21 and the second switch 22 being disconnected and the third switch 23 and the fourth switch 24 being connected, it also executes: a fourth step S40 of connecting one of the first switch 21 and the second switch 22; a fifth step S41 of connecting the third switch 23 and the fourth switch 24 after the fourth step S40; and a sixth step S42 of connecting the other of the first switch 21 and the second switch 22 after the fifth step S41.

[0117] The backup power supply device and control method thereof of the present disclosure are described above based on the embodiments and variations, etc., but the present disclosure is not limited to these embodiments and variations, etc. As long as it does not depart from the gist of the present disclosure, the embodiments and variations, etc. are implemented in various ways that can be obtained by a person skilled in the art, and other ways constructed by combining some of the constituent elements in the embodiments and variations, etc. are also included in the scope of the present disclosure.

[0118] For example, in Fig. 9 The backup power supply device 30a and Fig.10In the illustrated backup power supply device 30 b , the power storage element 25 b is charged by the main power supply 10 , but may be charged by a DC voltage source other than the main power supply 10 instead of or in addition to the main power supply 10 .

[0119] In addition, the storage element 25b is charged by a voltage after the DC voltage supplied from the main power supply 10 is stepped down, but the present invention is not limited to this mode, and the DC voltage supplied from the main power supply 10 may be charged without voltage conversion or with a stepped-up voltage. Similarly, the DC voltage output from the storage element 25b is supplied to the load 12 after being stepped up, but it may be supplied to the load 12 without voltage conversion or after being stepped down.

[0120] In the above-described embodiments, the first switch 21 , the second switch 22 , the third switch 23 , and the fourth switch 24 are formed of MOSFETs having parasitic diodes, but are not limited thereto and may be formed of other types of semiconductor switch elements and diode elements.

[0121] Industrial Applicability

[0122] The backup power supply device of the present disclosure is a backup power supply device that can suppress interruption of the supply voltage to the load when switching the power supply that supplies the DC voltage to the load. For example, it can be used as a power supply that backs up the supply of the DC voltage of a vehicle power supply (battery).

[0123] Description of Reference Numerals

[0124] 10 Main power supply

[0125] 12 Load

[0126] 20, 30, 30a, 30b, 30c, 30d backup power supply device

[0127] 21 First switch

[0128] 21a, 21c first MOSFET

[0129] 21b The first diode

[0130] 22 Second switch

[0131] 22a, 22c second MOSFET

[0132] 22b Second diode

[0133] 23 Third switch

[0134] 23a, 23c The third MOSFET

[0135] 23b The third diode

[0136] 24Fourth switch

[0137] 24a, 24c fourth MOSFET

[0138] 24b Fourth diode

[0139] 25 Auxiliary power supply

[0140] 25A step-down circuit

[0141] 25b Storage element

[0142] 25c boost circuit

[0143] 25d step-up and step-down circuit

[0144] 26, 31 control circuit

Claims

1. A backup power supply device for backing up the supply of DC voltage from a main power supply to a load, wherein: The backup power supply device comprises: a first switch inserted in a path connecting the main power source and the load, and turning on and off the supply of a DC voltage from the main power source to the load; a second switch inserted in a path connecting the first switch and the load, and turning on and off supply of a DC voltage to the load via the first switch; an auxiliary power supply, used for supplying a DC voltage to the load; a third switch inserted in a path connecting the auxiliary power supply and the load, and turning on and off the supply of a DC voltage from the auxiliary power supply to the load; a fourth switch inserted in a path connecting the third switch and the load, and turning on and off supply of a DC voltage to the load via the third switch; as well as The control circuit controls the first switch, the second switch, the third switch and the fourth switch.

2. The backup power supply device according to claim 1, wherein: The control circuit When the power supply for supplying a DC voltage to the load is switched from the main power supply to the auxiliary power supply, in a state where the first switch and the second switch are turned on and the third switch and the fourth switch are turned off, the following steps are performed: The first step is to disconnect one of the first switch and the second switch; A second step, after the first step, turning on the third switch and the fourth switch; as well as A third step is to turn off the other of the first switch and the second switch after the second step.

3. The backup power supply device according to claim 2, wherein: The third switch includes a third diode provided in a direction in which the current supplied from the auxiliary power supply flows toward the fourth switch when the third switch is turned off. In the second step, after the fourth switch is turned on, the third switch is turned on.

4. The backup power supply device according to claim 2, wherein: The fourth switch has a fourth diode, and the fourth diode is arranged in a direction to allow current to flow from the third switch to the load when the fourth switch is turned off. In the second step, after the third switch is turned on, the fourth switch is turned on.

5. The backup power supply device according to any one of claims 2 to 4, wherein: The control circuit further performs, when the power supply for supplying the DC voltage to the load is switched from the auxiliary power supply to the main power supply, in a state where the first switch and the second switch are turned off and the third switch and the fourth switch are turned on: The fourth step is to turn on one of the first switch and the second switch; A fifth step, after the fourth step, disconnecting the third switch and the fourth switch; as well as A sixth step is to turn on the other of the first switch and the second switch after the fifth step.

6. The backup power supply device according to claim 5, wherein: The third switch includes a third diode provided in a direction in which the current supplied from the auxiliary power supply flows toward the fourth switch when the third switch is turned off. In the fifth step, after the third switch is turned off, the fourth switch is turned off.

7. The backup power supply device according to claim 5, wherein: The fourth switch has a fourth diode, and the fourth diode is arranged in a direction to allow current to flow from the third switch to the load when the fourth switch is turned off. In the fifth step, after the fourth switch is turned off, the third switch is turned off.

8. The backup power supply device according to claim 1 or 2, wherein: The first switch includes a first diode provided in a direction in which the current supplied from the main power supply flows toward the second switch when the first switch is turned off. The second switch has a second diode, and the second diode is provided in a direction in which a current flows from the load to the first switch when the second switch is turned off. The third switch includes a third diode provided in a direction in which the current supplied from the auxiliary power supply flows toward the fourth switch when the third switch is turned off. The fourth switch includes a fourth diode provided in a direction in which a current flows from the load to the third switch when the fourth switch is turned off.

9. The backup power supply device according to claim 1 or 2, wherein: The first switch has a first diode, and the first diode is arranged in a direction that allows current to flow from the second switch to the main power supply when the first switch is turned off. The second switch has a second diode, and the second diode is arranged in a direction so that current flows from the first switch to the load when the second switch is turned off. The third switch has a third diode, and the third diode is arranged in a direction that allows current to flow from the fourth switch to the auxiliary power supply when the third switch is turned off. The fourth switch has a fourth diode provided in a direction in which a current flows from the third switch to the load when the fourth switch is turned off.

10. The backup power supply device according to claim 8 or 9, wherein: The first switch, the second switch, the third switch and the fourth switch are MOSFETs, The first diode, the second diode, the third diode, and the fourth diode are parasitic diodes of the MOSFET.

11. The backup power supply device according to any one of claims 1 to 10, wherein: The auxiliary power supply includes a power storage element that is charged with current supplied from the main power supply.

12. The backup power supply device according to claim 11, wherein: The auxiliary power supply also has: a step-down circuit that steps down a DC voltage supplied from the main power supply and charges the storage element; and The boost circuit boosts the DC voltage output from the power storage element and supplies the boosted DC voltage to the load via the third switch and the fourth switch.

13. A method for controlling a backup power supply device, the backup power supply device backing up the supply of a DC voltage from a main power supply to a load, wherein: The backup power supply device comprises: a first switch inserted in a path connecting the main power source and the load, and turning on and off the supply of a DC voltage from the main power source to the load; a second switch inserted in a path connecting the first switch and the load, and turning on and off supply of a DC voltage to the load via the first switch; an auxiliary power supply, used for supplying a DC voltage to the load; a third switch inserted in a path connecting the auxiliary power supply and the load, and turning on and off the supply of a DC voltage from the auxiliary power supply to the load; as well as a fourth switch inserted in a path connecting the third switch and the load, and turning on and off the supply of a DC voltage to the load via the third switch, The control method, when switching the power supply supplying the DC voltage to the load from the main power supply to the auxiliary power supply, in a state where the first switch and the second switch are turned on and the third switch and the fourth switch are turned off, includes: The first step is to disconnect one of the first switch and the second switch; A second step, after the first step, turning on the third switch and the fourth switch; and A third step is to turn off the other of the first switch and the second switch after the second step.

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