JP2007244021A - Dc power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a large capacity DC power supply in which harmonics are suppressed while sustaining high output voltage and high power factor through a simple constitution. <P>SOLUTION: Declines in DC output voltage and in power factor are avoided by providing: an AC power supply 1; a bridge rectification circuit 8; a smoothing capacitor 9; a plurality of reactors 2 and 3; a capacitor 12 connected between the joint of the reactors 2 and 3 and a DC output terminal through a two-way switch 11; a capacitor 14 connected between the AC input terminal of the bridge rectification circuit 8 and the DC output terminal through a two-way switch 13; a two-way switch 15 connected between the joint of the reactors 2 and 3 and the AC input terminal of the bridge rectification circuit 8; a detecting means 16 for detecting zero-cross of the AC power supply 1, A DC voltage detection means 18; and a two-way switch control means 17 for driving the two-way switches 11 and 13 based on the outputs from the zero-cross detection means 16 and the DC voltage detection means 18, and by switching the three two-way switches depending on the output quantity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a DC power supply device that uses a rectification method using a bridge rectifier circuit and supplies power to a device, a system, or the like with high power factor and low distortion.

  As a conventional DC power supply device that realizes low distortion with high power factor and suppressed harmonics, a device in which a capacitor is added to a full-wave rectifier circuit has been devised (see, for example, Patent Document 1). FIG. 9 shows a conventional DC power supply device described in Patent Document 1. In FIG. As shown in FIG. 9, a bridge rectifier circuit 8 composed of an AC power source 1, diodes 4 to 7, a smoothing capacitor 9, a reactor 2, a bidirectional switch 11, a capacitor 12, and a zero-cross detection means 16 The bidirectional switch drive signal generating means 24 and the bidirectional switch drive means 25 are configured. FIG. 10 is an operation waveform of each part of the conventional DC power supply device. The operation will be described with reference to FIG.

  When the bidirectional switch 11 is turned on with a delay of Δd from the zero cross point in the positive half cycle of the AC voltage, the AC power source 1 -reactor 2 -diode 4 -smoothing capacitor 9 -bidirectional switch 11 -capacitor 12- A series resonance current flows through the path of the AC power supply 1, and the charge of the capacitor 12 is discharged to the smoothing capacitor 9. When the bidirectional switch 11 is turned off Δt after the bidirectional switch 11 is turned on, the current flowing through the reactor 2 is continued as a normal full-wave rectification operation through the diodes 4 and 7. Next, in the negative half cycle of the AC voltage, when the bidirectional switch 11 is turned on with a delay of Δd from the zero cross point, the AC power source 1 -capacitor 12 -bidirectional switch 11 -diode 5 -reactor 2 -AC power source The charging current flows through the capacitor 12 through the path 1. When the bidirectional switch 11 is further turned off after Δt, the current flowing through the reactor 2 is continued through the diodes 6 and 5 as a normal full-wave rectification operation.

In the above configuration and operation, the inductance of the reactor 2 and the capacitance of the capacitor 12 are appropriately selected, and the Δd and Δt are appropriately set according to the load, thereby suppressing high harmonics and high power factor. And the DC output voltage can be controlled by the boosting action of the reactor 2 and the capacitor 12.
JP 2002-223571 A

  However, the conventional DC power supply device as described above has good characteristics in a relatively small capacity DC power supply device, but the DC output voltage and the power factor decrease when the capacity of the power supply is increased. Had. In particular, in order to realize a large-capacity power supply that satisfies the IEC harmonic regulations, it is necessary to increase the inductance of the reactor 2. As a result, the voltage drop due to the reactor 2 increases, the DC output voltage decreases, and the input current and There has been a problem that the power factor decreases due to an increase in the phase shift of the power supply voltage.

  The DC power supply apparatus of the present invention solves the conventional problems as described above, and an object thereof is to provide a DC power supply apparatus that can suppress a decrease in DC output voltage and power factor even at high output.

In order to solve the above problems, a DC power supply device of the present invention includes a bridge rectifier circuit that constitutes a plurality of reactors and a single-phase full-wave rectifier circuit, and is connected between a connection point between the reactors and a DC output terminal. A first capacitor connected via one bidirectional switch; a second capacitor connected via a second bidirectional switch between an AC input terminal and a DC output terminal of the bridge rectifier circuit; A third bidirectional switch connected between the intermediate connection point of the plurality of reactors and the AC input terminal of the bridge rectifier circuit is provided.

  As a result, the circuit operation corresponds to the case where the inductance of the reactor is reduced by closing the third bidirectional switch at the time of high output, and the capacitance of the first capacitor is further changed to the capacitance of the second capacitor. By setting a larger value and controlling only one of the first bidirectional switch or the second bidirectional switch according to the output amount of the DC power supply device, voltage drop and current phase shift due to the reactor are suppressed. Therefore, it is possible to suppress a decrease in output voltage and power factor at the time of small to large output.

  The direct-current power supply device of the present invention can suppress a decrease in direct-current output voltage and power factor even during large output while performing output voltage control.

  According to a first aspect of the present invention, there is provided an AC power source, a bridge rectifier circuit formed of four diodes for full-wave rectification of AC from the AC power source, a smoothing capacitor for smoothing the output of the bridge rectifier circuit, and the AC power source And a plurality of reactors connected in series between the AC input terminal of the bridge rectifier circuit and a connection point between the plurality of reactors and a DC output terminal via a first bidirectional switch. A first capacitor, a second capacitor connected between an AC input terminal and a DC output terminal of the bridge rectifier circuit via a second bidirectional switch, and a connection point between the plurality of reactors. A third bidirectional switch for opening and closing a connection with the AC input terminal of the bridge rectifier circuit; a zero cross detecting means for detecting a zero point of the voltage of the AC power supply; DC voltage detection means for detecting the voltage across the two terminals, and bidirectional switch control for driving the first bidirectional switch and the second bidirectional switch based on outputs of the zero-cross detection means and the DC voltage detection means By providing the means, switching between the first bidirectional switch, the second bidirectional switch, and the third bidirectional switch suppresses a DC output voltage and a power factor decrease at a small to large output. can do.

  In the second invention, in particular, the plurality of reactors according to the first invention is configured so that the total inductance value of the reactor on the AC power supply side from the connection point of the first bidirectional switch is greater than the total inductance value of the reactors on the other side. The DC power supply device is configured to set the inductance so as to be reduced, and by setting the inductance value of the reactor on the other side to be large, the reactor of the reactor on the AC power supply side from the connection point of the first bidirectional switch is set. Inductance can be reduced in size.

  In the third invention, in particular, the third bidirectional switch of the first invention or the second invention is closed when the first bidirectional switch is operated and the second bidirectional switch is off. It is the direct-current power supply device comprised as mentioned above, and can suppress the fall of a power factor.

  In the fourth invention, in particular, in the third bidirectional switch of the first invention or the second invention, the current flowing to the reactor on the bridge rectifier circuit side from the connection point of the first bidirectional switch becomes zero. The DC power supply device is configured to be opened at a point in time, and the occurrence of a voltage surge due to a sudden change in the current flowing through the plurality of reactors can be avoided.

  In the fifth invention, in particular, a fourth bidirectional switch is connected in series to a snubber circuit in which a snubber resistor and a snubber capacitor are connected in series to the third bidirectional switch of the first invention or the second invention. The connected DC power supply device can avoid a voltage surge generated from a reactor located on the bridge rectifier circuit side from the connection point of the first bidirectional switch.

  In the sixth invention, in particular, the third bidirectional switch of the first invention or the second invention has a predetermined amount of time until the current becomes zero from the zero crossing point of the voltage of the AC power supply to the third bidirectional switch. The DC power supply device is configured to be turned off after a lapse of time, and generation of a surge voltage due to a sudden change in current of a plurality of reactors can be avoided.

  The seventh invention is a DC power supply device in which the third bidirectional switch of the first invention or the second invention is constituted by a triac, and since it is possible to avoid generation of surge voltages in a plurality of reactors, The controllability of the bidirectional switch can be improved.

  In the eighth invention, in particular, the third bidirectional switch of the first invention or the second invention is closed when the input current supplied from the AC power source exceeds the first predetermined value, and the input current is A DC power supply device configured to be opened when it falls below a second predetermined value smaller than the first predetermined value, and the magnitude of the load is determined by the input current, and when the load is large, the third bidirectional By turning on the switch, it is possible to avoid a decrease in DC output voltage and power factor.

  In the ninth invention, in particular, when the third bidirectional switch of the first invention or the second invention is opened, the first bidirectional switch or the second bidirectional switch is opened at the same time. The DC power supply device configured as described above can avoid a sudden increase in DC output voltage.

  The tenth invention is a DC power supply device having saturable characteristics, in particular, a reactor located on the AC power supply side from the connection point of the first bidirectional switches of the first to ninth inventions. It is possible to reduce the size of the reactor on the AC power supply side from the connection point of the direction switch.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
In FIG. 1, a bridge rectifier circuit 8 has a configuration in which four diodes 4 to 7 are connected to form a single-phase full-wave rectifier circuit. In addition to the reactor 2, the reactor 3 is inserted in series with the reactor 2 and in an AC line to which the capacitor 12 and the capacitor 14 are connected. The connection point between the reactors 2 and 3 and the DC output terminal are connected via the first bidirectional switch 11 and the first capacitor 12, and the connection point between the reactors 2 and 3 and the reactor 3 are connected in the second bidirectional direction. The connection points of the switches 13 are connected via a third bidirectional switch 15. The inductances of the reactors 2 and 3 and the capacitances of the first capacitor 12 and the second capacitor are set appropriately according to the output of the first bidirectional switch 11 and the second bidirectional switch 13 as described below. The value is set in advance so that the harmonics of the input current clear the IEC harmonic regulation when turned on and off. The inductance of the reactor 2 is set to a value smaller than the inductance of the reactor 3, and the first capacitor 11 is set to be larger than the second capacitor 14.

  The circuit operation of FIG. 1 in the above configuration will be described. First, in a region where the output is relatively small, the third bidirectional switch 15 is turned off, the first bidirectional switch 11 is turned off, and the second bidirectional switch operates in the same manner as a conventional DC power supply device. Do. At this time, as shown in FIG. 2, the ON time of the second bidirectional switch 13 is relatively short, and the voltage Vc of the second capacitor 14 is also in a state of being DC biased with little fluctuation. As the output increases, Δd in FIG. 2 is decreased and Δt is increased in order to suppress harmonics and maintain the DC output voltage. If the output further increases, Δd = 0, and the second bidirectional switch 13 is turned on from the zero crossing of the voltage. As the output increases, the fluctuation range of the voltage Vc of the second capacitor 14 increases, and eventually fluctuates between zero and the DC output voltage Vo.

  FIGS. 2A and 2B are operation waveform examples of each part when a relatively large output is output in a state where the third bidirectional switch 15 is still off. The power supply voltage is 230 V, 50 Hz, The inductance is 5 mH, the inductance of the reactor 9 is 13 mH, the capacitance of the smoothing capacitor 7 is 3300 μF, the capacitance of the second capacitor 14 is 100 μF, and the input power is 3.5 kW. At this operating point, the DC output voltage is about 270 V and the power factor is 96%, which is a good characteristic. Further, the harmonics of the input current are also below the IEC harmonic regulation value 19 as shown in FIG.

  FIG. 3A shows the input current IL8 and the DC output voltage Vo when the load is further increased in this state and the input power reaches 5.0 kW. At this operating point, the DC output voltage is significantly reduced to about 200 V. For example, when this power supply device is used as a DC motor drive power supply, the desired maximum motor speed cannot be obtained. It is possible that this will occur. Further, the input current IL8 is greatly out of phase with the power supply voltage Vi, and as a result, the power factor is greatly reduced to about 79%. Accordingly, in the conventional circuit configuration, the output range is practically suppressed to a smaller value, and the output cannot be expanded.

  Here, when the third bidirectional switch 15 is turned on at the voltage zero-crossing point, almost no current flows through the reactor 3 and the reactor 3 is bypassed, and the reactor inductance is apparently reduced. Become. Details of this operation will be described with reference to FIGS. 1 and 3B and 3C. First, when the second bidirectional switch 13 is turned on in the positive half cycle of the AC power source 1, the AC power source 1-the reactor 2-the third bidirectional switch 15-the second bidirectional switch 13-the second capacitor The charging current flows through the second capacitor 14 through the path of 14-diode 7-AC power supply 1. Next, when the second bidirectional switch 13 is turned off, a current path of AC power source 1-reactor 2-third bidirectional switch 15-diode 4-smoothing capacitor 9-diode 7-AC power source 1 is formed, Most of the current flowing from the AC power supply 1 passes through this path. As a result, most of the current flowing from the AC power source 1 passes through the third bidirectional switch 15, and the current flowing through the reactor 3 becomes a very small value (see FIG. 3C).

  When the second bidirectional switch 13 is turned on in the negative half cycle of the AC power supply 1, the AC power supply 1-diode 6-smoothing capacitor 9-second capacitor 14-second bidirectional switch 13-third The charge of the second capacitor 14 is discharged to the smoothing capacitor 9 through the path of the bidirectional switch 15 -reactor 2 -AC power supply 1. Next, when the second bidirectional switch 13 is turned off, a current path of AC power source 1-diode 6-smoothing capacitor 9-diode 5-third bidirectional switch 15-reactor 2-AC power source 1 is formed. Most of the current that flows from the power supply 1 passes through this path. As a result, most of the current flowing from the AC power source 1 passes through the third bidirectional switch 15, and the current flowing through the reactor 3 becomes a very small value (see FIG. 3C).

  With the above operation, the current waveform of the reactor 2 becomes IL8 shown in FIG. 3, the current of the reactor 3 becomes IL9, and the current of the third bidirectional switch 15 becomes almost the same as the current waveform of the reactor 2. Here, as described above, the current of the reactor 3 becomes a very small value when the third bidirectional switch 15 is turned on. This means that when the third bidirectional switch 15 is turned on, the reactor 3 is bypassed, and the action of its inductance component is almost eliminated. As a result, the output as shown in the waveform of FIG. The voltage Vo maintains a high value of about 270V. Further, since there is no phase shift between the power supply voltage Vi and the input current IL8, the power factor is as high as about 95%.

Next, in a region where the output is larger, the third bidirectional switch 15 remains on, the second bidirectional switch 13 is turned off, and the first bidirectional switch 11 is the same as in the conventional DC power supply device. Perform the operation. The capacitance of the first capacitor 12 is set to be as large as 400 μF with respect to the capacitance of the second capacitor 14 being 100 μF. The details of the operation at this time are the same as the operation of the second bidirectional switch, but the charge / discharge current of the first capacitor flowing in each mode is larger than that of the second capacitor, so the output is Even in a larger region, the output voltage Vo and the power factor can be maintained. When the second bidirectional switch is in operation, it was the limit to maintain 6.0 kW while maintaining a high power factor even if the pulse was extended to the limit, whereas the first bidirectional switch was in operation As shown in FIG. 4, the input power is 9.0 kW, the output voltage Vo is maintained at a high value of about 270 V, and the power factor is realized at a high value of about 95%.

  Further, when the first bidirectional switch 11 is operated, the input power can be output up to 9.0 kW while maintaining a high output voltage and a high power factor, but 6.0 kW even if the pulse width is narrowed to the limit. Can not output lower power. That is, in the medium output power region, it is necessary to switch to the mode in which the third bidirectional switch 15 is on, the first bidirectional switch 11 is off, and the second bidirectional switch is controlled.

(Embodiment 2)
In the second embodiment, the inductance value is set so that the inductance value of the reactor 2 of the first embodiment is smaller than the inductance value of the reactor 3. In the circuit configuration of the first embodiment, the reactors 2 and 3 are equivalent to one reactor with the inductance added when the third bidirectional switch 15 is turned off at the small to medium output. On the other hand, when the third bidirectional switch 15 is turned on, the current flowing through the reactor 3 is very small as described above, so that the current flowing through the reactor 3 can be kept lower than the current flowing through the reactor 2. . Therefore, in this embodiment, as described above, the inductance of the reactor 2 is set to 5 mH, the inductance of the reactor 3 is set to 13 mH larger than the reactor 2, and the total inductance value of both reactors is secured to 18 mH. Thus, by setting the inductance of the reactor 2 having a large current low and setting the inductance of the reactor 3 having a relatively small current large, the reactor 2 can be downsized.

(Embodiment 3)
In the third embodiment, when the first bidirectional switch 11 of the first embodiment operates and the second bidirectional switch 13 is off, the third bidirectional switch is closed. When the third bidirectional switch 15 is turned off while the first bidirectional switch 11 is operating, the connection point of the first bidirectional switch 11 is between the reactor 2 and the reactor 3, and FIG. Since the current flowing through the AC input terminal of the bridge rectifier circuit 8 is reduced as shown in the waveform of FIG. 5, the charge / discharge current of the first capacitor 12 is increased in a distorted form as shown in FIG. Therefore, the current flowing through the reactor 2 is as shown in FIG. 5A, and the power factor is greatly reduced to 82%. Therefore, when the first bidirectional switch 11 is operating, a mode in which the power factor is lowered can be prevented by adding a restriction that the third bidirectional switch 15 is turned on.

(Embodiment 4)
In the fourth embodiment, the third bidirectional switch 15 of the first embodiment is opened when the current flowing through the reactor 3 becomes zero. When the output required for the DC power supply device becomes low, the third bidirectional switch 15 is turned off when the current of the third bidirectional switch 15 becomes zero. By this operation, it is possible to avoid the occurrence of a voltage surge due to a sudden change in the current flowing through the reactors 2 and 3.

(Embodiment 5)
FIG. 6 shows a configuration diagram of the third bidirectional switch 15 of the first embodiment of the DC power supply device according to the fifth embodiment of the present invention. In FIG. 6, a fourth bidirectional switch 20 is connected in series to a snubber circuit 23 in which a snubber resistor 21 and a snubber capacitor 22 are connected in series, and these are connected in parallel to a third bidirectional switch 15. ing. When the output required for the DC power supply device becomes low, the fourth bidirectional switch 20 is turned on simultaneously with the third bidirectional switch 15 being turned off. The loop current flowing through the reactor 3 of the first form and the third bidirectional switch 15 is attenuated by the snubber circuit 23, and when the loop current becomes zero, the fourth bidirectional switch 20 is turned off. With this operation, a voltage surge generated from the reactor 3 can be avoided even if the third bidirectional switch 15 is turned off at an arbitrary phase instead of the zero cross point of the voltage.

(Embodiment 6)
In the sixth embodiment, the third bidirectional switch 15 of the first embodiment is turned off after a lapse of a predetermined time from the zero cross point of the voltage of the AC power supply 1 until the current of the third bidirectional switch 15 becomes zero. I have to. The current flowing through the third bidirectional switch 15 is substantially the same as IL8 in FIG. 3B, and becomes zero in the second half of the AC half cycle. An appropriate timing is set in the current zero period, and the third bidirectional switch 15 is turned off after a predetermined time elapses from the voltage zero crossing point to the set timing. Since the zero crossing point of the voltage is necessary for the control of the first bidirectional switch 11 or the second bidirectional switch 13, the detection means is already provided, and without the addition of any parts by using the control, It is possible to turn off the third bidirectional switch 15 in a section where the current of the third bidirectional switch 15 becomes zero by simple control, and it is possible to avoid generation of a surge voltage due to a sudden change in the current of the reactors 2 and 3.

(Embodiment 7)
In the seventh embodiment, the third bidirectional switch 15 in the first embodiment is configured by a triac. With the above configuration, even if the third bidirectional switch 15 is turned off at an arbitrary timing, it is actually turned off when the current becomes zero, and generation of a surge voltage in the reactors 2 and 3 can be avoided. The controllability of the third bidirectional switch 15 is improved.

(Embodiment 8)
In the eighth embodiment, when the input current supplied from the AC power supply 1 to the third bidirectional switch 15 in the first embodiment exceeds the first predetermined value, the third bidirectional switch 15 is closed, and the input current Is less than a second predetermined value smaller than the first predetermined value, the third bidirectional switch 15 is opened. As shown in FIG. 7, when the load is relatively light and the third bidirectional switch 15 is turned off, the load increases and the input current IL8 increases. When the load exceeds the first predetermined value, the third bidirectional switch is reached. Switch 15 is turned on. When the load becomes light again and the input current IL10 falls below the second predetermined value, the third bidirectional switch 15 is turned off. Here, the first predetermined value is set to a value larger than the second predetermined value. When the third bidirectional switch 15 is turned on, the first bidirectional switch 11 or the second bidirectional switch 13 is turned off simultaneously.

  With the above operation, the load magnitude is determined by the input current IL8, and when the load is large, the third bidirectional switch 15 is turned on to avoid a decrease in the DC output voltage and the power factor. Further, since the first predetermined value is set to be larger than the second predetermined value, it is possible to avoid the hunting phenomenon in which the third bidirectional switch 15 is repeatedly turned on and off.

(Embodiment 9)
In the ninth embodiment, when the third bidirectional switch in the first embodiment is closed, the first bidirectional switch 11 or the second bidirectional switch 13 is opened at the same time. When the third bidirectional switch 15 is turned on while the on-duty of the first bidirectional switch 11 or the second bidirectional switch 13 is maintained, the DC output voltage suddenly rises several tens of volts at that moment, resulting in the behavior of the load. In this case, the third bidirectional switch 15 is turned on and at the same time the first bidirectional switch 11 or the second bidirectional switch 13 is turned off. Are canceled out, and a sudden rise in the DC output voltage can be avoided.

(Embodiment 10)
In the tenth embodiment, the reactor 2 is provided with a saturable characteristic, and as shown in FIG. 8, 5 mH is secured when the current flowing through the reactor 2 is smaller than the predetermined value ILo, and the inductance decreases when the current becomes larger than the predetermined value ILo. The characteristics are as follows. By providing this characteristic, it is possible to secure sufficient inductance to suppress power source harmonics in the small to medium power region, and the inductance decreases in the large power region, so that the voltage drop and current phase of the reactor 2 are reduced. The shift is suppressed, which is advantageous for increasing the output. Further, since the maximum energy stored in the reactor 2 can be reduced, the reactor 2 can be downsized.

  As described above, the DC power supply device according to the present invention can achieve both a high power factor at the time of high output and output voltage maintenance, and therefore can be applied to applications such as a high output inverter air conditioner.

Configuration diagram of DC power supply apparatus according to Embodiment 1 of the present invention FIG. 6 is an operation waveform diagram of each part at a relatively large output of the DC power supply device according to Embodiment 1 of the present invention, and an explanatory diagram showing a comparison between harmonic components and IEC harmonic regulation values (A) Waveform diagram showing input current and output voltage at the time of large output of the conventional DC power supply device (b), (c) Operation waveform diagram of each part at the time of large output of the DC power supply device in Embodiment 1 of the present invention Operation waveform diagram of each part at the time of large output of the DC power supply device when controlling the first bidirectional switch in the first embodiment of the present invention (A), (b) Operation waveform diagram of each part at the time of large output of the DC power supply device in Embodiment 4 of the present invention Configuration diagram of third bidirectional switch according to embodiment 4 of the present invention Operation explanatory diagram of the third bidirectional switch according to the eighth embodiment of the present invention. Characteristic diagram of current and inductance of reactor 2 in the tenth embodiment of the present invention Configuration diagram according to an example of a conventional DC power supply device Explanatory drawing which shows the comparison with each part operation waveform and harmonic component and harmonic regulation domestic guideline concerning an example of the conventional DC power supply device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power source 2 1st reactor 3 2nd reactor 4-7 Diode 8 Bridge rectifier circuit 9 Smoothing capacitor 10 Load 11 1st bidirectional switch 12 1st capacitor 13 2nd bidirectional switch 14 2nd capacitor DESCRIPTION OF SYMBOLS 15 3rd bidirectional switch 16 Zero cross detection means 17 Bidirectional switch control means 18 DC voltage detection means 19 IEC harmonic regulation value 20 4th bidirectional switch 21 Snubber resistance 22 Snubber capacitor 23 Snubber circuit 24 Bidirectional switch drive signal Generating means 25 Bidirectional switch driving means

Claims (10)

An AC power supply, a bridge rectifier circuit formed by four diodes for full-wave rectification of AC from the AC power supply, a smoothing capacitor for smoothing the output of the bridge rectifier circuit, the AC power supply, and the bridge rectifier circuit A plurality of reactors connected in series with an AC input terminal; a first capacitor connected via a first bidirectional switch between a connection point between the plurality of reactors and a DC output terminal; A second capacitor connected between an AC input terminal and a DC output terminal of the bridge rectifier circuit via a second bidirectional switch; a connection point between the plurality of reactors; and an AC of the bridge rectifier circuit A third bidirectional switch that opens and closes a connection with the input terminal, zero-cross detection means for detecting a zero point of the voltage of the AC power supply, and electric power at both ends of the smoothing capacitor. DC voltage detection means for detecting the first cross switch, and bidirectional switch control means for driving the first bidirectional switch and the second bidirectional switch based on the outputs of the zero cross detection means and the DC voltage detection means. DC power supply characterized by the above. The plurality of reactors are set such that the total inductance value of the reactor on the AC power supply side from the connection point of the first bidirectional switch is smaller than the total inductance value of the reactor on the other side. The direct current power supply device described in 1. 3. The DC power supply device according to claim 1, wherein the third bidirectional switch is closed when the first bidirectional switch operates and the second bidirectional switch is off. 3. The DC power supply device according to claim 1, wherein the third bidirectional switch is opened when the current flowing through the plurality of reactors becomes zero. 4. 3. A snubber circuit formed of a snubber resistor and a snubber capacitor, and a circuit in which the snubber circuit and a fourth bidirectional switch are connected in series are configured in parallel with a third bidirectional switch. The direct current power supply device described. The DC power supply device according to claim 1 or 2, wherein the third bidirectional switch is opened after a predetermined time has elapsed from a zero cross point of the AC power supply. The DC power supply device according to claim 1 or 2, wherein the third bidirectional switch is configured by a triac. When the input current supplied from the AC power source exceeds a first predetermined value, the third bidirectional switch is closed, and when the input current falls below a second predetermined value smaller than the first predetermined value, The DC power supply device according to claim 1, wherein the bidirectional switch is opened. The DC power supply device according to any one of claims 1 to 8, wherein when the third bidirectional switch is closed, the first bidirectional switch or the second bidirectional switch is simultaneously opened. The DC power supply device according to any one of claims 1 to 9, wherein a saturable characteristic is given to a reactor on the AC power supply side among the plurality of reactors.

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