JPWO2013136775A1 - DC power supply - Google Patents

Abstract

The bridge rectifier circuit (109) in the DC power supply device includes a first switching circuit (110a) including a first switching element (105a) and a first diode (104a) connected in antiparallel, and an antiparallel connection. A second switching circuit (110b) configured by the second switching element (105b) and the second diode (104b), and the current path in each of the first switching circuit and the second switching circuit An excessive current detection unit (108b, 108c, 108d, 108e, 108f, 108g) is provided that interrupts the current path when a current greater than or equal to a predetermined current flows in the current path.

Description

  The present invention relates to a DC power supply device that uses a circuit that converts AC power to DC power and supplies power to devices, systems, and the like with high power factor and low distortion.

  Conventionally, as a circuit system of a DC power supply device up to about several kW output, a two-stone high-frequency switching system using two switching elements has been mainly employed for improving input power factor and reducing harmonic current. (For example, refer to Patent Document 1).

  FIG. 6 shows a conventional high-frequency switching DC power supply described in Patent Document 1. In FIG. 6 includes an AC power supply 301, a fuse 308a, a filter circuit 303, a reactor 302, diodes 304a, 304b, 304c, and 304d, switching elements 305a and 305b, and a smoothing capacitor 306. A DC power supply is supplied to the load 307.

  The conventional DC power supply device shown in FIG. 6 has a circuit configuration in which two switching elements are used and the number of semiconductor elements through which current passes is two. In this two-stone high frequency switching type DC power supply device, each switching element alternately performs a step-up chopper operation every half cycle according to the polarity of the AC input power supply. In the conventional DC power supply device shown in FIG. 6, the input power factor is improved by reducing the number of semiconductor elements through which a current flows to reduce the loss while making the input current sinusoidal.

  In the conventional DC power supply device, as shown in FIG. 6, a fuse 308 a is provided immediately after the output of the AC power supply 301 for the purpose of circuit protection such as a rectifier circuit. By providing the fuse 308a immediately after the output of the AC power supply 301 in this manner, the safety of the circuit when an overcurrent is input from the AC power supply 301 in some abnormal mode is ensured.

JP-A-1-117658

  However, when the conventional DC power supply device as shown in FIG. 6 is applied to, for example, an air conditioner having a power factor correction device, it is necessary to select a fuse 308a having a large current rating. In order to coordinate with such a large rated fuse 308a, it is necessary to use a switching element with a large rating according to the rating of the fuse 308a, and the DC power supply apparatus has a problem of significant cost increase. Had.

  The present invention solves the problems in the conventional DC power supply device as described above, and can select a fuse having a small current rating and a switching element having a small current rating, thereby reducing the size and cost. An object of the present invention is to provide a DC power supply device that can be realized.

In order to solve the conventional problem, the DC power supply device of the present invention is:
AC power supply,
A first diode, a second diode, a first switching element connected in antiparallel to the first diode, and a second switching element connected in antiparallel to the second diode, A bridge rectifier circuit that rectifies AC from an AC power supply;
A reactor connected between the AC power supply and the input side of the bridge rectifier circuit;
A smoothing capacitor for smoothing the DC output of the bridge rectifier circuit,
The bridge rectifier circuit includes a first switching circuit configured by the first switching element and the first diode connected in anti-parallel, and the second switching element connected in anti-parallel and the second switching circuit. A second switching circuit constituted by a diode;
An overcurrent detection unit is provided in each of the current paths in the first switching circuit and the two switching circuits and shuts off the current path when a current of a predetermined current or more flows in the current path.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at loss reduction with a simple structure, while being able to improve an input power factor, size reduction and cost reduction of a DC power supply device are realizable.

The block diagram which shows the circuit structure of the direct-current power supply device of Embodiment 1 which concerns on this invention. Operation explanatory diagram showing a current path according to the polarity of the AC power supply in the first embodiment according to the present invention The block diagram which shows the circuit structure of the DC power supply device of Embodiment 2 which concerns on this invention. The block diagram which shows the circuit structure of the DC power supply device of Embodiment 3 which concerns on this invention. The block diagram which shows the circuit structure of the DC power supply device of Embodiment 4 which concerns on this invention. Block diagram showing the circuit configuration of a conventional DC power supply (2-stone type)

The direct current power supply device according to the first aspect of the present invention includes:
AC power supply,
A first diode, a second diode, a first switching element connected in antiparallel to the first diode, and a second switching element connected in antiparallel to the second diode, A bridge rectifier circuit that rectifies AC from an AC power supply;
A reactor connected between the AC power supply and the input side of the bridge rectifier circuit;
A smoothing capacitor for smoothing the DC output of the bridge rectifier circuit,
The bridge rectifier circuit includes a first switching circuit configured by the first switching element and the first diode connected in anti-parallel, and the second switching element connected in anti-parallel and the second switching circuit. A second switching circuit constituted by a diode;
An overcurrent detection unit is provided in each of the current paths in the first switching circuit and the two switching circuits and shuts off the current path when a current of a predetermined current or more flows in the current path.

  In the DC power supply device of the first aspect according to the present invention configured as described above, the input power factor can be improved while reducing loss with a simple configuration, and the current rating is small. An excessive current detector, for example, a fuse and a switching element with a small current rating can be selected, and downsizing and cost reduction can be realized.

  In the DC power supply device according to the second aspect of the present invention, the overcurrent detection unit in the first aspect is connected in series to the first switching element and the first diode connected in reverse parallel. The first fuse, the second switching element connected in reverse parallel, and the second fuse connected in series to the second diode may be used. In the DC power supply device according to the second aspect of the present invention configured as described above, the current flowing through the first fuse and the second fuse is applied to the fuse on the common line provided immediately after the output of the AC power supply. It becomes smaller than the flowing current. Accordingly, it is possible to select the first fuse and the second fuse having specifications with a small current rating, and it is possible to select a switching element having a small current rating according to a fuse with a small current rating. . For this reason, in the DC power supply device according to the second aspect of the present invention, the DC power supply device can be reduced in size and cost.

  In the DC power supply device according to the third aspect of the present invention, the overcurrent detection unit in the first aspect includes the first diode, the second diode, the first switching element, and the first switching element. A plurality of fuses connected in series to each of the two switching elements may be used. In the DC power supply device according to the third aspect of the present invention configured as described above, it is possible to select fuses connected to each diode and each switching element and having a specification with a smaller current rating. The degree of freedom in selecting each element increases while reducing the size and cost of the device, and as a result, the use as a DC power supply device widens.

  In the DC power supply device according to the fourth aspect of the present invention, a plurality of the excessive current detection units in the first aspect are connected in series to the first switching element and the second switching element, respectively. You may comprise by the fuse of. In the DC power supply device according to the fourth aspect of the present invention configured as described above, it is possible to use a fuse having a small current rating for the fuse connected to each switching element, and a small package as the switching element. The size can be selected, and the cost reduction of the apparatus can be realized. In the DC power supply device according to the fourth aspect of the present invention, the fuse connected in series with each of the first switching element or the second switching element is blown even if the switching element is short-circuited for some reason. By doing so, it is possible to continue the operation through other current paths in the bridge rectifier circuit.

  According to a fifth aspect of the present invention, there is provided a DC power supply apparatus according to the first aspect, further comprising a common line fuse provided in a common line immediately after the output of the AC power supply, wherein the overcurrent detection unit A plurality of fuses connected in series to each of one diode and the second diode may be used. In the DC power supply device of the fifth aspect according to the present invention configured as described above, it is possible to use a fuse having a small current rating for the fuse connected to each diode, and the diode has a small package size. The cost can be reduced. Furthermore, in the DC power supply device according to the fifth aspect of the present invention, even if the switching element is short-circuited for some reason, the common line inserted into the common line of the first switching element and the second switching element. Since the fuse is blown, the AC power supply and the bridge circuit are disconnected, so that the operation can be stopped safely and reliably.

  Hereinafter, a power supply device including a DC power supply device as an embodiment of the DC power supply device of the present invention will be described with reference to the accompanying drawings. Note that the DC power supply device of the present invention is not limited to the configuration described in the following embodiment, and is configured based on a technical idea equivalent to the technical idea described in the following embodiment. Includes a power supply.

(Embodiment 1)
FIG. 1 is a block diagram showing a circuit configuration of a DC power supply device according to Embodiment 1 of the present invention.

  In FIG. 1, the current output from the output terminal of the AC power supply 101 is input to the bridge rectifier circuit 109 via the filter circuit 103 and the reactor 102. A smoothing capacitor 106 and a load 107 are connected in parallel to the output of the bridge rectifier circuit 109.

  In the DC power supply device of the first embodiment, the common line fuse 108a for protecting the bridge rectifier circuit 109 from the overcurrent when an overcurrent flows from the AC power supply 101 has a common line immediately after the output of the AC power supply 101. (Common current path).

  As shown in FIG. 1, in the bridge rectifier circuit 109, the first switching element 105a and the second switching element 105b are connected in antiparallel to the first diode 104a and the second diode 104b, respectively. A first switching circuit 110a and a second switching circuit 110b are configured. The first switching circuit 110a and the second switching circuit 110b are each provided with an excessive current detection unit (108b, 108c) described later. The two switching circuits 110a and 110b are connected in series. In the bridge rectifier circuit 109, diodes 104c and 104d are connected in series to form a series circuit, and a series circuit in which two switching circuits 110a and 110b are connected in series is connected in parallel to the series circuit. Connected.

  In the DC power supply device of the first embodiment, as described above, the switching circuits 110a and 110b are provided with the excessive current detection units (108b and 108c), and the excessive current detection units (108b and 108c). Has a function of instantaneously interrupting the current path when the current flowing through the inserted current path (line) exceeds a predetermined current. The fuses 108b and 108c are used as the excessive current detection units (108b and 108c) in the first embodiment. In the first embodiment, a fuse 108b which is an overcurrent detection unit is provided in a current path (line) between the anti-parallel circuit of the first diode 104a and the first switching element 105a and the reactor 102. . Further, a fuse 108c, which is an excessive current detection unit, is provided in a current path (line) between the anti-parallel circuit of the second diode 104b and the second switching element 105b and the reactor 102.

  Next, the operation of the DC power supply device according to the first embodiment will be described with reference to FIG. FIG. 2 is an operation explanatory diagram showing a current path according to the polarity of the AC power supply 101. 2, (a) is a current path when the polarity of the AC power supply 101 is positive, (b) is a current path when the polarity of the AC power supply 101 is negative, and (c) is two switching elements 105a. , 105b are current paths when they are simultaneously turned on. In FIG. 2, the block description of the filter circuit 103, the bridge rectifier circuit 109, the first switching circuit 110a, and the second switching circuit 110b is omitted for explanation.

  First, the operation when the polarity of the AC power supply 101 is positive will be described with reference to FIG. The case where the polarity of the AC power supply 101 is positive means that the upper terminal voltage of the AC power supply 101 is higher than the lower terminal voltage in FIG. At this time, the first switching element 105a on the upper side in FIG. 2A is turned off.

  In FIG. 2A, when the second switching element 105b on the lower side is in the OFF state, the common line fuse 108a, the reactor 102, the fuse 108b, the first diode 104a, and the smoothing capacitor 106 are supplied from the AC power supply 101. The current Ia flows in the order of the diode 104d. A current path through which the current Ia flows is indicated by a solid arrow in FIG.

  In FIG. 2A, when the second switching element 105b is in the on state, the current Ib is supplied from the AC power source 101 in the order of the common line fuse 108a, the reactor 102, the fuse 108c, the second switching element 105b, and the diode 104d. Flowing. A current path through which the current Ib flows is indicated by a dashed arrow in FIG. This current Ib is a reactor charging current that accumulates energy in the reactor 102.

  Next, the operation when the polarity of the AC power supply 101 is negative will be described with reference to FIG. The case where the polarity of the AC power supply 101 is negative means that the lower terminal voltage of the AC power supply 101 is higher than the upper terminal voltage in FIG. At this time, the second switching element 105b in FIG. 2B is turned off.

  In FIG. 2B, when the first switching element 105a is in the OFF state, the AC power supply 101 is followed by the diode 104c, the smoothing capacitor 106, the second diode 104b, the fuse 108c, the reactor 102, and the common line fuse 108a in this order. A current Ic flows. A current path through which the current Ic flows is indicated by a solid arrow in FIG.

  In FIG. 2B, when the first switching element 105a is in the ON state, the current Id is supplied from the AC power supply 101 in the order of the diode 104c, the first switching element 105a, the fuse 108b, the reactor 102, and the common line fuse 108a. It can flow. A current path through which the current Id flows is indicated by a dashed arrow in FIG. This current Id is a reactor charging current that accumulates energy in the reactor 102.

  As described above, since the current supply path is switched every half-wave according to the polarity of the power supply current from the AC power supply 101, the fuses 108b and 108c provided in the first switching circuit 110a and the second switching circuit 110b are switched. The current value flowing through each of the currents is half of the current value flowing through the common line fuse 108a provided immediately after the output of the AC power supply 101. As a result, it is possible to use the fuses 108b and 108c provided in the first switching circuit 110a and the second switching circuit 110b with a capacity having a small rated current.

  For example, in an air conditioner having a power factor correction device that consumes 4 kW class power, a common line fuse 108a of a variety having a rating of about 30 A is generally used as an overcurrent prevention fuse. When selecting a switching element capable of coordinating with the common line fuse 108a having such a rating, a switching element having a larger capacity than the specification selected in the steady state is selected.

  However, the fuses 108b and 108c provided in the switching circuits 110a and 110b can be selected to have a smaller rating than the common line fuse 108a. For example, in an air conditioner having a power factor correction device that consumes 4 kW class power, a fuse rated at about 15 A, which is about half the common line fuse 108 a rated at about 30 A, can be used.

  Therefore, the switching elements 105a and 105b that are selected according to the rating of the fuse can be selected according to the originally required specifications according to the load 107.

  Therefore, it is not necessary to select switching elements 105a and 105b having a current rating higher than necessary, and it is not necessary to select a type having a package size larger than necessary. As a result, according to the configuration of the first embodiment, the DC power supply device can be reduced in size and cost, and the degree of freedom in selecting the switching element can be expanded.

  Further, in the DC power supply device of the first embodiment, when some abnormality occurs and the first switching element 105a and the second switching element 105b are turned on at the same time, as shown in FIG. It becomes a direct current short circuit state. Usually, in a DC power supply device, if a protection circuit is configured assuming a DC short-circuit state, the circuit configuration becomes complicated, resulting in an increase in cost and an increase in mounting area.

  However, in the DC power supply device according to the first embodiment, the first switching circuit 110a and the second switching circuit 110b are each provided with the fuses 108b and 108c that are the excessive current detection units, and therefore when the DC short circuit occurs. Since a fuse is present on the current path, the circuit can be protected and the safety of the DC power supply device can be improved with a simple configuration.

(Embodiment 2)
Next, a DC power supply device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing a circuit configuration of the DC power supply device according to the second embodiment of the present invention. In FIG. 3, elements having substantially the same functions and configurations as those of the first embodiment are given the same numbers. Since the basic operation in the second embodiment is the same as the basic operation in the first embodiment, the differences in the second embodiment from the first embodiment will be mainly described.

  In FIG. 3, the current output from the output terminal of the AC power supply 101 is input to the bridge rectifier circuit 109 via the filter circuit 103 and the reactor 102. The bridge rectifier circuit 109 is configured by a parallel circuit of a series connection circuit formed of an anti-parallel connection circuit of switching elements 105a and 105b and diodes 104a and 104b and a series connection circuit formed of diodes 104c and 104d. A smoothing capacitor 106 and a load 107 are connected in parallel to the output of the bridge rectifier circuit 109.

  As shown in FIG. 3, in the bridge rectifier circuit 109 according to the second embodiment, each of the diodes 104a and 104b and the switching elements 105a and 105b includes fuses 108d, 108e, 108f, and 108g that are overcurrent detection units, respectively. It is connected.

  In the configuration of the second embodiment, the first switching circuit 110a includes the first switching element 105a connected in reverse parallel to the first diode 104a, and fuses 108d and 108e that are overcurrent detection units. Has been. In addition, the second switching circuit 110b includes fuses 108f and 108g which are excessive current detection units, together with the second switching element 105b connected in antiparallel with the second diode 104b. As shown in FIG. 3, the excessive current detection unit in the second embodiment is connected in series to each of the first diode 104a, the second diode 104b, the first switching element 105a, and the second switching element 105b. It is composed of a plurality of fuses 108d, 108e, 108f and 108g.

  As described above, in bridge rectifier circuit 109 according to the second embodiment, the current rating of each element is set by inserting a fuse on the power supply side of each element of each of diodes 104a and 104b and each of switching elements 105a and 105b. The circuit can be made small, and the circuit can be reduced in size and cost.

  In addition, in the DC power supply device of the second embodiment configured as described above, it is possible to select a diode and a switching element having a low rating. For example, the diodes 104a and 104b are selected from the switching elements 105a and 105b. It is possible to select a product with a small package size, further increasing the degree of freedom of selecting each component, and expanding the application as a DC power supply device.

(Embodiment 3)
Next, a DC power supply device according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a circuit configuration of the DC power supply device according to the third embodiment of the present invention. In FIG. 4, elements having substantially the same functions and configurations as those of the first and second embodiments are given the same numbers. Further, the basic operation in the third embodiment is the same as the basic operation in the first embodiment, and therefore, the difference from the first embodiment will be mainly described in the third embodiment.

  In FIG. 4, the current output from the output terminal of the AC power supply 101 is input to the bridge rectifier circuit 109 via the filter circuit 103 and the reactor 102. The bridge rectifier circuit 109 is configured by a parallel circuit of a series connection circuit formed of an anti-parallel connection circuit of switching elements 105a and 105b and diodes 104a and 104b and a series connection circuit formed of diodes 104c and 104d. A smoothing capacitor 106 and a load 107 are connected in parallel to the output of the bridge rectifier circuit 109.

  As shown in FIG. 4, in the bridge rectifier circuit 109 according to the third embodiment, the fuse 108e, which is an overcurrent detection unit, is connected to the first switching element 105a, and the overcurrent detection is performed to the second switching element 105b. The fuse 108g which is a part is connected.

  In the configuration of the third embodiment, the first switching circuit 110a includes the first switching element 105a connected in antiparallel with the first diode 104a and a fuse 108e that is an overcurrent detection unit. Yes. The second switching circuit 110b includes a fuse 108g that is an excessive current detection unit, together with a second switching element 105b connected in antiparallel with the second diode 104b. As shown in FIG. 4, the excessive current detection unit in the third embodiment includes a plurality of fuses 108e and 108g connected in series to the first switching element 105a and the second switching element 105b.

  As described above, in bridge rectifier circuit 109 according to the third embodiment, by inserting fuses 108e and 108g into switching elements 105a and 105b, the current rating of switching elements 105a and 105b is further reduced. It becomes possible to do. As a result, in the DC power supply device according to the third embodiment, the wire bonding strength of each switching element 105a, 105b can be incorporated into the device even if it is not as strong as that of each diode 104a, 104b. A product having a small size can be selected, the degree of freedom in selecting a switching element is increased, and the cost can be reduced.

  Further, when the switching elements 105a and 105b are short-circuited for some reason, the fuses 108e and 108g are selected so that the fuses 108e and 108g have a smaller current rating than the common line fuse 108a. Since the fuse is blown, the common line fuse 108a is not blown. In this case, since the diode rectification function of the rectification bridge circuit 109 is still alive, the operation is continued with the configuration of the diode rectification circuit. That is, in the configuration of the DC power supply device according to the third embodiment, even if the switching element in the rectifier bridge circuit 109 is short-circuited, the operation can be continued with a safe circuit configuration. As an application can be expanded.

(Embodiment 4)
Next, a DC power supply apparatus according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing a circuit configuration of the DC power supply device according to the fourth embodiment of the present invention. In FIG. 5, elements having substantially the same functions and configurations as those in the first to third embodiments are assigned the same numbers. Since the basic operation in the fourth embodiment is the same as the basic operation in the first embodiment, the differences from the first embodiment will be mainly described in the fourth embodiment.

  In FIG. 5, the current output from the output terminal of the AC power supply 101 is input to the bridge rectifier circuit 109 via the filter circuit 103 and the reactor 102. The bridge rectifier circuit 109 is configured by a parallel circuit of a series connection circuit formed of an anti-parallel connection circuit of switching elements 105a and 105b and diodes 104a and 104b and a series connection circuit formed of diodes 104c and 104d. A smoothing capacitor 106 and a load 107 are connected in parallel to the output of the bridge rectifier circuit 109.

  As shown in FIG. 5, in the bridge rectifier circuit 109 according to the fourth embodiment, a fuse 108d that is an excessive current detector is connected to the first diode 104a, and a fuse that is an excessive current detector is connected to the second diode 104b. 108f is connected.

  In the configuration of the fourth embodiment, the first switching circuit 110a includes the first switching element 105a connected in antiparallel with the first diode 104a and a fuse 108d that is an overcurrent detection unit. Yes. In addition, the second switching circuit 110b includes a fuse 108f that is an excessive current detection unit, together with the second switching element 105b connected in antiparallel with the second diode 104b. As shown in FIG. 5, the excessive current detection unit in the fourth embodiment includes a plurality of fuses 108d and 108f connected in series to the first diode 105a and the second diode 105b.

  As described above, in bridge rectifier circuit 109 in the fourth embodiment, current rating of each diode 104a, 104b is further reduced by inserting fuses 108d, 108f into each of diodes 104a, 104b. Is possible. As a result, in the DC power supply device according to the fourth embodiment, since the wire bonding strength of each of the diodes 104a and 104b is not as strong as that of the respective switching elements 105a and 105b, it can be incorporated into the device. It is possible to select a product with a small size, increasing the degree of freedom in selecting a diode, and can be applied not only to general rectifier diodes but also to fast recovery diodes and SiC. For this reason, in the configuration of the DC power supply device of the fourth embodiment, in addition to cost reduction, there is an effect that the uses of the DC power supply device are further expanded.

  Further, when the first switching element 105a and the second switching element 105b are short-circuited for some reason, the overcurrent flows through the common line fuse 108a, so that the common line fuse 108a is instantaneously blown. As a result, in the DC power supply device of the fourth embodiment, the DC power supply device is disconnected from the AC power supply 101, and the operation of the DC power supply device is reliably stopped. That is, in the configuration of the DC power supply device according to the fourth embodiment, even if the first switching element 105a and the second switching element 105b are short-circuited at the same time, the operation can be stopped safely. Applications can be expanded as a high DC power supply.

  In the DC power supply device according to each embodiment of the present invention, an example has been described in which each switching circuit is provided with an overcurrent detection unit, and this overcurrent detection unit is configured with a fuse. As long as the current flowing through the current path exceeds a predetermined current, the line may be cut off instantly, and is not limited to a fuse.

  As described above, in the DC power supply device of the present invention, by inserting a fuse into the switching circuit in the bridge rectifier circuit, the current flowing through the fuse is smaller than the current flowing through the fuse of the common line immediately after the AC power supply. Thus, a fuse having a small current rating can be selected, and an element having a small current rating can be selected in the switching circuit.

  As described above, according to the present invention, it is possible to improve the input power factor while reducing loss with a simple configuration, and it is possible to reduce the size and cost of the DC power supply device.

  The direct current power supply device of the present invention can improve the input power factor while reducing loss with a simple configuration, and can be applied as a direct current power supply device for appliances such as air conditioners and refrigerators and washing machines. .

DESCRIPTION OF SYMBOLS 101 AC power supply 102 Reactor 103 Filter circuit 104a, 104b, 104c, 104d Diode 105a, 105b Switching element 106 Smoothing capacitor 107 Load 108a Common line fuse 108b, 108c, 108d, 108e, 108f, 108g Fuse (overcurrent detection part)
109 Bridge adjustment circuit 110a, 110b Switching circuit

Claims (5)

AC power supply,
A first diode, a second diode, a first switching element connected in antiparallel to the first diode, and a second switching element connected in antiparallel to the second diode, A bridge rectifier circuit that rectifies AC from an AC power supply;
A reactor connected between the AC power supply and the input side of the bridge rectifier circuit;
A smoothing capacitor for smoothing the DC output of the bridge rectifier circuit,
The bridge rectifier circuit includes a first switching circuit configured by the first switching element and the first diode connected in anti-parallel, and the second switching element connected in anti-parallel and the second switching circuit. A second switching circuit constituted by a diode;
A direct-current power supply device provided with an excessive current detection part which is provided in each current course in the 1st switching circuit and the 2 switching circuit, and intercepts the current course, when a current beyond a predetermined current flows through the current course.   The overcurrent detection unit includes the first switching element connected in reverse parallel, the first fuse connected in series to the first diode, the second switching element connected in reverse parallel, and the second switching element. The DC power supply device according to claim 1, comprising: a second fuse connected in series to the diode.   2. The overcurrent detection unit includes a plurality of fuses connected in series to each of the first diode, the second diode, the first switching element, and the second switching element. The direct current power supply device described.   2. The DC power supply device according to claim 1, wherein the excessive current detection unit includes a plurality of fuses connected in series to each of the first switching element and the second switching element. A common line fuse provided in a common line immediately after the output of the AC power supply,
2. The DC power supply device according to claim 1, wherein the excessive current detection unit includes a plurality of fuses connected in series to each of the first diode and the second diode.

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