JP2008043092A - Switching power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power supply wherein power supply efficiency can be effectively improved. <P>SOLUTION: The switching power supply is so constructed that: the center tap of an isolation transformer is connected to a first output terminal (TOUT1) through an output inductor, the cathodes of first and second diodes (D1, D2) for rectification are connected to one end and the other end of the secondary winding of the isolation transformer, and the anodes of the first and second diodes for rectification are connected to a second output terminal (TOUT2). The switching power supply is provided with: capacitors (CS11, CS21) whose electrodes on one side are connected to the cathode of the first or second diode for rectification, diodes (DS13, DS23) connected between the electrodes of the capacitors on the other side and the first output terminal, and diodes (DS12, DS22) and inductors (LS12, LS22) connected between the electrodes of the capacitors on the other side and the second output terminal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a switching power supply device, and more particularly to a technique for absorbing a surge generated by a rectifying diode provided on a secondary side of a transformer provided in the switching power supply device.

  FIG. 15 shows a configuration of a conventional switching power supply device. The switching power supply device shown in the figure includes an input capacitor Cin, switches S1 to S4, an insulating transformer T, rectifying diodes DA and DB, an output inductor Lout, an output capacitor Cout, and a switching control circuit SC. According to this switching power supply device, the DC input voltage Vin is converted into an AC voltage by the switching operation of the full bridge circuit composed of the switches S1 to S4 and supplied to the primary winding L1 of the isolation transformer T. In the secondary windings L21 and L22, a desired AC voltage corresponding to the winding ratio is induced. The AC voltage is rectified by the rectifying diodes DA and DB, and then smoothed by the output inductor Lout and the output capacitor Cout to become the DC output voltage Vout. The DC output voltage Vout is output to the outside.

  By the way, according to the above-described conventional switching power supply device, when the direction of the voltage induced in the secondary windings L21 and L22 of the insulation transformer T is switched by the switching operation of the full bridge circuit including the switches S1 to S4, Due to the parasitic inductance due to the secondary winding and wiring, a surge as illustrated in FIG. 16 occurs on the cathode side of the rectifying diodes DA and B. That is, when the direction of the voltage induced in the secondary windings L21 and L22 is switched, the rectifying diode DA or DB is put in a reverse bias state. At this time, the energy stored in the parasitic inductance in the so-called recovery period. Is instantaneously released, and this becomes a surge and is applied to the rectifying diode DA or the rectifying diode DB.

  Generally, the above-described surge can be improved to some extent by adding a known CR snubber circuit to the rectifying diodes DA and DB. However, since the CR snubber circuit is based on the principle of absorbing a surge by consuming power with a resistive element, it inherently causes a power loss and causes a reduction in power supply efficiency. Further, since the resistance element generates heat when absorbing the surge by the CR snubber circuit, the size of the resistance element constituting the CR snubber circuit is increased in consideration of the heat dissipation.

As a conventional technique for solving such a problem of the CR snubber circuit, there is a lossless snubber circuit in which surge energy is temporarily stored in a coil and discharged to the output side (see Patent Document 1).
JP 09-224374 A

  According to the above-described lossless snubber circuit according to the prior art, a large number of elements are interposed on the current path until the surge is discharged to the output side, and power loss occurs in each of these elements. There is a problem that there is a limit.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a switching power supply device capable of absorbing a surge generated in a rectifying diode while effectively suppressing a decrease in power supply efficiency. .

  The present invention includes an insulation transformer having a center tap provided on the secondary side, the center tap is connected to a first terminal via an output inductor, and the first end and the other end of the secondary winding of the insulation transformer are connected to the first terminal. Output terminals (for example, components corresponding to the cathode) of the first and second rectifier elements (for example, components corresponding to the rectifier diode) are connected, respectively, and input terminals (for example, to the anode) of these first and second rectifier elements are connected. In the switching power supply device in which the corresponding component is commonly connected to the second terminal, a capacitor having one electrode connected to the output terminal of the first or second rectifying element, the other electrode of the capacitor, and the A first rectifier circuit connected between the first terminal and forming a charging path for the capacitor; and connected between the other electrode of the capacitor and the second terminal. Having a configuration of a switching power supply apparatus being characterized in that a second rectifier circuit constituting the discharge path of the capacitor.

  The present invention comprises an insulating transformer provided with a center tap on the secondary side, and the output terminals of the first and second rectifying elements are connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device in which the input terminals of the first and second rectifying elements are commonly connected to the second terminal, a capacitor having one electrode connected to the output terminal of the first or second rectifying element, A first rectifier circuit connected between the other electrode and the second terminal and forming a charging path for the capacitor, and connected between the other electrode of the capacitor and the second terminal, and discharging the capacitor The switching power supply device includes a second rectifier circuit that forms a path.

  The present invention comprises an insulating transformer provided with a center tap on the secondary side, and the output terminals of the first and second rectifying elements are connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device in which the input terminals of the first and second rectifying elements are commonly connected to the second terminal, a capacitor having one electrode connected to the output terminal of the first or second rectifying element, A first rectifier circuit connected between the other electrode and the center tap and forming a charging path of the capacitor; and connected between the other electrode of the capacitor and the second terminal; and a discharging path of the capacitor And a second rectifier circuit configured as described above.

  The present invention includes an insulating transformer provided with a center tap on the secondary side, and the input terminals of the first and second rectifying elements are connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply apparatus in which the output terminals of the first and second rectifying elements are commonly connected to the first terminal via an output inductor, and the center tap is connected to the second terminal, A capacitor having one electrode connected to the output terminal; a first rectifier circuit connected between the other electrode of the capacitor and the first terminal and forming a charging path for the capacitor; and the other electrode of the capacitor And a second rectifier circuit connected between the first terminal and the second terminal to form a discharge path of the capacitor.

  The present invention includes an insulating transformer provided with a center tap on the secondary side, and each input terminal of the first and second rectifying elements is connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device, a capacitor having one electrode connected to an output terminal of the first or second rectifying element, and a connection between the other electrode of the capacitor and the input terminal of the first or second rectifying element. And a second rectifier that is connected between the first rectifier circuit that forms a charging path of the capacitor, and the other electrode of the capacitor and the input terminal of the first or second rectifier element, and that forms a discharge path of the capacitor. A switching power supply device comprising a circuit.

  The present invention includes an insulating transformer provided with a center tap on the secondary side, and each input terminal of the first and second rectifying elements is connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device, a capacitor having one electrode connected to an input terminal of the first or second rectifying element, a capacitor connected between the other electrode of the capacitor and the center tap, and a charging path of the capacitor And a second rectifier circuit connected between the other electrode of the capacitor and the output terminal of the first or second rectifier element and forming a discharge path of the capacitor. It has the structure of the switching power supply device.

  The present invention provides a switching power supply device in which one end and the other end of a secondary winding of an isolation transformer are connected to first and second input portions of a full-wave rectifier circuit, respectively, and the first input portion of the full-wave rectifier circuit A capacitor to which one electrode is connected, a first rectifier circuit that is connected between the other electrode of the capacitor and the second input portion of the full-wave rectifier circuit and forms a charging path for the capacitor, and the capacitor And a second rectifier circuit connected between the other electrode of the full-wave rectifier circuit and the second input portion of the full-wave rectifier circuit, and forming a discharge path of the capacitor.

  In the present invention, one end and the other end of the secondary winding of the isolation transformer are respectively connected to the first and second input portions of the full-wave rectifier circuit, and the first output portion of the full-wave rectifier circuit is connected via an output inductor. A switching power supply device connected to a first terminal and having a second output portion of the full-wave rectifier circuit connected to a second terminal, a capacitor having one electrode connected to the first output portion of the full-wave rectifier circuit And connected between the other electrode of the capacitor and the first terminal, and connected between the first rectifier circuit forming the charging path of the capacitor, and the other electrode of the capacitor and the second terminal. And a second rectifier circuit that forms a discharge path of the capacitor.

  In the present invention, one end and the other end of the secondary winding of the isolation transformer are respectively connected to the first and second input portions of the full-wave rectifier circuit, and the first output portion of the full-wave rectifier circuit is connected via an output inductor. In the switching power supply device connected to the first terminal, a capacitor having one electrode connected to the first output portion of the full-wave rectifier circuit and a connection between the other electrode of the capacitor and the first terminal And a first rectifier circuit that forms a charging path for the capacitor, a second rectifier circuit that is connected between the other electrode of the capacitor and the first or second input terminal of the full-wave rectifier circuit, and that forms a discharge path for the capacitor. And a switching power supply device comprising a rectifier circuit.

  In the present invention, one end and the other end of the secondary winding of the isolation transformer are respectively connected to the first and second input portions of the full-wave rectifier circuit, and the first output portion of the full-wave rectifier circuit is connected via an output inductor. In a switching power supply device connected to a first terminal and having a second output portion of the full-wave rectifier circuit connected to a second terminal, one electrode is connected to the first or second input portion of the full-wave rectifier circuit A capacitor, a first rectifier circuit connected between the other electrode of the capacitor and the first terminal and forming a charging path of the capacitor, and between the other electrode of the capacitor and the second terminal And a second rectifier circuit that forms a discharge path of the capacitor, and has a configuration of a switching power supply device.

  The present invention provides a switching power supply device in which one end and the other end of a secondary winding of an isolation transformer are connected to first and second input portions of a full-wave rectifier circuit, respectively. A capacitor having one electrode connected to one of the two input units; a first rectifier circuit connected between the other electrode of the capacitor and the first terminal and forming a charging path for the capacitor; and The switching power supply device includes a second rectifier circuit that is connected between the other electrode and the other of the first and second input portions and forms a discharge path of the capacitor.

  According to the present invention, the surge generated by the rectifying diode is temporarily stored in the capacitor, and the power stored in the capacitor is discharged to the output side via the inductor, so that power loss can be achieved with a simple configuration. Surge can be absorbed while effectively suppressing

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
First, a first embodiment corresponding to the invention of claim 1 will be described with reference to FIG.
FIG. 1 shows a configuration of a switching power supply device according to the present embodiment.
The configuration on the primary side of the insulation transformer T1 in the figure is the same as the primary side of the insulation transformer T in the conventional device shown in FIG. 15, and in FIG. Omitted.

  As shown in FIG. 1, the switching power supply device includes an insulating transformer T1 provided with a center tap TP, and a rectifier circuit including rectifier diodes D1 and D2 on its secondary side (output side); A smoothing circuit including the output inductor Lout and the output capacitor Cout is connected. That is, the output inductor Lout is connected between the center tap TP provided on the secondary side of the isolation transformer T1 and the first output terminal TOUT1, and the secondary winding of the isolation transformer T1 including the secondary windings L21 and L22. The cathodes of the first and second rectifying diodes D1 and D2 are respectively connected to one end and the other end of the line, and the anodes of the rectifying diodes D1 and D2 are commonly connected to the second output terminal TOUT2. A load R fed by the switching power supply device is connected between the output terminal TOUT1 and the output terminal TOUT2.

  The switching power supply apparatus includes a capacitor CS11, a diode DS12, an inductor LS12, and a diode DS13 as a first snubber circuit for absorbing a surge generated in the rectifying diode D1, and a surge generated in the rectifying diode D2. As a second snubber circuit for absorbing the above, a capacitor CS21, a diode DS22, an inductor LS22, and a diode DS23 are provided.

Here, each configuration of the snubber circuit will be described in detail.
One electrode of the capacitor CS11 constituting the first snubber circuit is connected to the cathode of the rectifying diode D1. A diode DS13 is connected between the other electrode of the capacitor CS11 and the first output terminal TOUT1. That is, the anode of the diode DS13 is connected to the other electrode of the capacitor CS11, and the cathode of the diode DS13 is connected to the first output terminal TOUT1. The diode DS13 functions as a rectifier circuit that forms a charging path for the capacitor CS11.

  A series circuit including the inductor LS12 and the diode DS12 is connected between the other electrode of the capacitor CS11 and the second output terminal TOUT2. That is, one end of the inductor LS12 is connected to the other electrode of the capacitor CS11, the other end of the inductor LS12 is connected to the cathode of the diode DS12, and the anode of the diode DS12 is connected to the second output terminal TOUT2. The inductor LS12 and the diode DS12 function as a rectifier circuit that forms a discharge path of the capacitor CS11.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CS21 constituting the second snubber circuit is connected to the cathode of the rectifying diode D2. A diode DS23 is connected between the other electrode of the capacitor CS21 and the first output terminal TOUT1. That is, the anode of the diode DS23 is connected to the other electrode of the capacitor CS21, and the cathode of the diode DS23 is connected to the first output terminal TOUT1. The diode DS23 functions as a rectifier circuit that forms a charging path for the capacitor CS21.

  In addition, a series circuit including an inductor LS22 and a diode DS22 is connected between the other electrode of the capacitor CS21 and the second output terminal TOUT2. That is, one end of the inductor LS22 is connected to the other electrode of the capacitor CS21, the other end of the inductor LS22 is connected to the cathode of the diode DS22, and the anode of the diode DS22 is connected to the second output terminal TOUT2. The inductor LS22 and the diode DS22 function as a rectifier circuit that forms a discharge path of the capacitor CS21.

  The configuration on the primary side of the insulation transformer T1 is the same as that of the conventional device shown in FIG. 15 described above, and the configuration will be described for confirmation with reference to FIG. An input capacitor Cin is connected between the input terminal TIN1 and the input terminal TIN2, a switch S1 and a switch S2 are connected in series in this order, and a switch S3 and a switch S4 are connected in series in this order. One end of the primary winding L1 of the transformer T1 shown in FIG. 1 is connected to the connection point between the switch S1 and the switch S2, and the primary winding is connected to the connection point between the switch S3 and the switch S4. The other end of the line L1 is connected. The switches S1, S2, S3 and S4 constitute a full bridge type switching circuit, and the opening and closing of each switch is controlled by a switching control circuit SC. However, the configuration of the switching circuit on the primary side of the isolation transformer T1 is not limited to this example, and other types of switching circuits such as a half bridge type may be employed.

Next, the operation of the present switching power supply device will be described.
First, a normal power conversion operation will be briefly described. In FIG. 15 to be used, the switching circuit composed of the switches S1 to S4 performs a predetermined switching operation (known switching operation), whereby the DC input voltage Vin is converted into an AC voltage, and the transformer T1 shown in FIG. Supplied to the primary winding L1. As a result, AC voltages are respectively induced in the secondary windings L21 and L22 of the insulating transformer T1. The AC voltages induced in the secondary windings L21 and L22 are rectified by rectifying diodes D1 and D2. The rectified voltage is smoothed by the output inductor Lout and the output capacitor Cout, and is output to the outside through the output terminals TOUT1 and TOUT2 as a desired DC output voltage Vout.

Next, taking the rectifying diode D2 as an example, the absorption operation of the surge generated in the rectifying diode D2 will be described in detail.
In an initial state, voltages are induced in the secondary windings L21 and L22 of the isolation transformer T1 in such a direction that the rectifying diode D2 is biased in the forward direction and the rectifying diode D1 is biased in the reverse direction. And In this state, the voltage induced in the secondary winding L22 is rectified by the rectifying diode D2 and output to the first output terminal TOUT1 and the second output terminal TOUT2.

  When the direction of each voltage induced in the secondary windings L21 and L22 of the insulation transformer T1 is reversed in accordance with the switching operation on the primary side from the initial state, the rectifying diode D1 is forward biased and rectified. The diode D2 is biased in the reverse direction, but the rectifier diode D2 is kept on during the so-called recovery period. For this reason, an overcurrent flows in a loop composed of the secondary windings L21 and L22 of the insulating transformer T1 and the rectifying diodes D1 and D2, and the energy is transferred to the parasitic inductors such as the secondary windings L21 and L22 and wiring. Accumulated.

  When the recovery period elapses, the rectifying diode D2 shifts to an off state, thereby interrupting the overcurrent loop. As a result, energy accumulated in the parasitic inductor existing on the cathode side of the rectifying diode D2 during the recovery period is instantaneously released, and a surge is generated at the cathode of the rectifying diode D2. The current caused by this surge is represented by a charging path CR1 (capacitor CS21 to diode DS23 to first output terminal TOUT1 to load R to second output terminal TOUT2 to rectifier diode D1 to secondary windings L21 and L22 to Flows along the capacitor CS21), thereby charging the capacitor CS21.

  Thereafter, the rectifying diode D1 is biased in the reverse direction in the process of reversing the direction of each voltage induced in the secondary windings L21 and L22 of the isolation transformer T1 with the switching operation on the primary side. The rectifying diode D2 is biased in the forward direction. In this case, the electric charge accumulated in the capacitor CS21 is discharged from the discharge path DR1 (capacitor SC21 to secondary winding L22 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 shown by a one-dot chain line in FIG. -Diode DS22-Inductor LS22-Capacitor CS21), thereby discharging capacitor CS21.

  Thus, according to the present embodiment, energy due to the surge generated at the cathode of the rectifying diode D2 is temporarily stored in the capacitor CS21 and then discharged to the output side via the inductor LS22. Since the phase of the discharge current at this time is delayed with respect to the phase of the voltage by the inductor LS22, the loss in the diode DS22 expressed as the product of the voltage and the current is suppressed. Similarly, the energy generated by the surge generated in one of the rectifying diodes D1 is temporarily stored in the capacitor CS11 and then discharged to the output side through the inductor LS12 with low loss.

  Thus, the surge generated in the rectifying diodes D1 and D2 is effectively absorbed (suppressed), and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

<Second Embodiment>
Next, a second embodiment corresponding to the second aspect of the present invention will be described with reference to FIG.
The switching power supply according to the present embodiment replaces the snubber circuit in the configuration of FIG. 1 according to the first embodiment described above with a capacitor CS211 as a first snubber circuit for absorbing a surge generated in the rectifying diode D1, A diode DS212, an inductor LS212, and a diode DS213 are provided, and a capacitor CS221, a diode DS222, an inductor LS222, and a diode DS223 are provided as a second snubber circuit for absorbing a surge generated in the rectifying diode D2. Other configurations are the same as those of the first embodiment.

Here, each configuration of the snubber circuit in the second embodiment will be described in detail.
One electrode of the capacitor CS211 constituting the first snubber circuit is connected to the cathode of the rectifying diode D1. A diode DS213 is connected between the other electrode of the capacitor CS211 and the second output terminal TOUT2. That is, the anode of the diode DS213 is connected to the other electrode of the capacitor CS211, and the cathode of the diode DS213 is connected to the second output terminal TOUT2. The diode DS213 functions as a rectifier circuit that forms a charging path for the capacitor CS211.

  In addition, a series circuit including a diode DS212 and an inductor LS212 is connected between the other electrode of the capacitor CS211 and the second output terminal TOUT2. That is, the cathode of the diode DS212 is connected to the other electrode of the capacitor CS211, the anode of the diode DS212 is connected to one end of the inductor LS212, and the other end of the inductor LS212 is connected to the second output terminal TOUT2. The diode DS212 and the inductor LS212 function as a rectifier circuit that forms a discharge path of the capacitor CS211.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CS221 constituting the second snubber circuit is connected to the cathode of the rectifying diode D2. A diode DS223 is connected between the other electrode of the capacitor CS221 and the second output terminal TOUT2. That is, the anode of the diode DS223 is connected to the other electrode of the capacitor CS221, and the cathode of the diode DS223 is connected to the second output terminal TOUT2. The diode DS223 functions as a rectifier circuit that forms a charging path for the capacitor CS221.

  In addition, a series circuit including a diode DS222 and an inductor LS222 is connected between the other electrode of the capacitor CS221 and the second output terminal TOUT2. That is, the cathode of the diode DS222 is connected to the other electrode of the capacitor CS221, the anode of the diode DS222 is connected to one end of the inductor LS222, and the other end of the inductor LS222 is connected to the second output terminal TOUT2. The diode DS222 and the inductor LS222 function as a rectifier circuit that forms a discharge path of the capacitor CS221.

Next, the surge absorbing operation generated in the rectifying diode D2 will be described in detail by taking the rectifying diode D2 as an example. Note that the normal power conversion operation is the same as in the first embodiment described above, and is therefore omitted.
First, from the state where the rectifying diode D2 is biased in the forward direction, the direction of each voltage induced in the secondary windings L21 and L22 of the insulating transformer T1 is reversed in accordance with the switching operation on the primary side, and the rectifying diode When the diode D2 is biased in the reverse direction, as described above, the energy accumulated in the parasitic inductor in the so-called recovery period is instantaneously released, and a surge is generated at the cathode of the rectifying diode D2.

  In the present embodiment, the current caused by the surge flows along the charging path CR2 (capacitor CS221 to diode DS223 to rectifier diode D1 to secondary windings L21 and L22 to capacitor CS221) indicated by a dotted line in FIG. CS 221 is charged.

  Thereafter, the rectifying diode D2 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding of the isolation transformer T1 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CS221 is discharged in a discharge path DR2 (capacitor CS221 to secondary winding L22 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 shown by a one-dot chain line in FIG. ~ Inductor LS222 ~ diode DS222 ~ capacitor CS221), thereby discharging capacitor CS221.

  Thus, according to this embodiment, since the cathode of the diode DS212 is connected to the anode of the diode DS213, these two diodes can be configured as one component, which is compared with the first embodiment described above. Thus, the number of parts can be reduced. The same applies to the diodes DS222 and DS223.

<Third Embodiment>
Next, a third embodiment corresponding to the invention according to claim 3 will be described with reference to FIG.
The switching power supply according to the present embodiment replaces the snubber circuit in the configuration of FIG. 1 according to the first embodiment described above with a capacitor CS311 as a first snubber circuit for absorbing a surge generated in the rectifying diode D1, A diode DS312, an inductor LS312 and a diode DS313 are provided, and a capacitor CS321, a diode DS322, an inductor LS322, and a diode DS323 are provided as a second snubber circuit for absorbing a surge generated in the rectifying diode D2. Other configurations are the same as those of the first embodiment.

Here, each configuration of the snubber circuit in the third embodiment will be described in detail.
One electrode of the capacitor CS311 constituting the first snubber circuit is connected to the cathode of the rectifying diode D1. A diode DS313 is connected between the other electrode of the capacitor CS311 and the center tap TP. That is, the anode of the diode DS313 is connected to the other electrode of the capacitor CS311, and the cathode of the diode DS313 is connected to the center tap TP. The diode DS313 functions as a rectifier circuit that forms a charging path for the capacitor CS311.

  In addition, a series circuit including a diode DS312 and an inductor LS312 is connected between the other electrode of the capacitor CS311 and the second output terminal TOUT2. That is, one end of the inductor LS312 is connected to the other electrode of the capacitor CS311, the other end of the inductor LS312 is connected to the cathode of the diode DS312 and the anode of the diode DS312 is connected to the second output terminal TOUT2. The diode DS312 and the inductor LS312 function as a rectifier circuit that forms a discharge path of the capacitor CS311.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CS321 constituting the second snubber circuit is connected to the cathode of the rectifying diode D2. A diode DS323 is connected between the other electrode of the capacitor CS321 and the center tap TP. That is, the anode of the diode DS323 is connected to the other electrode of the capacitor CS321, and the cathode of the diode DS323 is connected to the center tap TP. The diode DS323 functions as a rectifier circuit that forms a charging path for the capacitor CS321.

  A series circuit including a diode DS322 and an inductor LS322 is connected between the other electrode of the capacitor CS321 and the second output terminal TOUT2. That is, one end of the inductor LS322 is connected to the other electrode of the capacitor CS321, the other end of the inductor LS322 is connected to the cathode of the diode DS322, and the anode of the diode DS322 is connected to the second output terminal TOUT2. The diode DS322 and the inductor LS322 function as a rectifier circuit that forms a discharge path of the capacitor CS321.

Next, taking the rectifying diode D2 as an example, the absorption operation of the surge generated in the rectifying diode D2 will be described in detail. Note that the normal power conversion operation is the same as in the first embodiment described above, and is therefore omitted.
First, from the state where the rectifying diode D2 is biased in the forward direction, the direction of each voltage induced in the secondary windings L21 and L22 of the insulating transformer T1 is reversed in accordance with the switching operation on the primary side, and the rectifying diode When the diode D2 is biased in the reverse direction, the energy accumulated in the parasitic inductor in the so-called recovery period is instantaneously released as described above, and a surge is generated at the cathode of the rectifying diode D2.

  In the present embodiment, the current due to the surge flows along a charging path CR3 (capacitor CS321 to diode DS323 to secondary winding L22 to capacitor CS321) indicated by a dotted line in FIG. 3, thereby charging the capacitor CS321.

  Thereafter, the rectifying diode D2 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding of the isolation transformer T1 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor C321 is discharged from the discharge path DR3 (capacitor CD321 to secondary winding L22 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 shown by a one-dot chain line in FIG. ~ Diode DS322 ~ Inductor LS322 ~ Capacitor CS321), thereby discharging the capacitor CS321.

Thus, according to this embodiment, since the anode of the diode DS312 is connected to the anode of the rectifying diode D1, these two diodes can be configured as one component, and the first embodiment described above. The number of parts can be reduced compared to The same applies to the diode DS322 and the rectifying diode D2.
In the first to third embodiments described above, the discharge path of the surge accumulated in the capacitor is basically the same, and only the charging path is different.

<Fourth embodiment>
With reference to FIG. 4, a fourth embodiment corresponding to the fourth aspect of the present invention will be described.
FIG. 4 shows a configuration of the switching power supply device according to the present embodiment. The configuration on the primary side of the insulation transformer T1 in the figure is the same as the primary side of the insulation transformer T in the conventional device shown in FIG. Is omitted.

  As shown in FIG. 4, the switching power supply device includes an insulating transformer T1 provided with a center tap TP, and a rectifier circuit including rectifier diodes D41 and D42 on its secondary side (output side); A smoothing circuit including the output inductor Lout and the output capacitor Cout is connected. That is, the anodes of the first and second rectifying diodes D41 and D42 are respectively connected to one end and the other end of the secondary winding of the insulating transformer T1 including the secondary windings L21 and L22. , D42 are commonly connected to the first output terminal TOUT1 through the output inductor Lout, the center tap TP of the isolation transformer T1 is connected to the second output terminal TOUT2, and between the output terminal TOUT1 and the output terminal TOUT2 A load R fed by the switching power supply device is connected.

  The switching power supply device includes a capacitor CS41, a diode DS42, an inductor LS42, and a diode DS43 as a snubber circuit for absorbing a surge generated in the rectifying diodes D41 and D42.

Here, the configuration of the snubber circuit will be described in detail.
One electrode of the capacitor CS41 constituting the snubber circuit is connected to the cathode of the rectifying diode D1. A diode DS43 is connected between the other electrode of the capacitor CS41 and the first output terminal TOUT1. That is, the anode of the diode DS43 is connected to the other electrode of the capacitor CS41, and the cathode of the diode DS43 is connected to the first output terminal TOUT1. The diode DS43 functions as a rectifier circuit that forms a charging path for the capacitor CS41.

In addition, a series circuit including the inductor LS42 and the diode DS42 is connected between the other electrode of the capacitor CS41 and the second output terminal TOUT2. That is, the cathode of the diode DS42 is connected to the other electrode of the capacitor CS41, one end of the inductor LS42 is connected to the anode of the diode DS42, and the other end of the inductor LS42 is connected to the second output terminal TOUT2. . The inductor LS42 and the diode DS42 function as a rectifier circuit that forms a discharge path of the capacitor CS41.
The configuration of the primary side of the insulating transformer T1 is the same as that of the conventional device shown in FIG. 15, and the description thereof is omitted.

Next, the operation of the present switching power supply device will be described.
First, a normal power conversion operation will be briefly described. In FIG. 15 to be used, when the switching circuit composed of the switches S1 to S4 performs a predetermined switching operation (a well-known switching operation), the DC input voltage Vin is converted into an AC voltage, and the transformer T1 shown in FIG. Supplied to the primary winding L1. As a result, AC voltages are induced in the secondary windings L21 and L22, respectively. The AC voltages induced in the secondary windings L11 and L12 are rectified by rectifying diodes D41 and D42. The rectified voltage is smoothed by the output inductor Lout and the output capacitor Cout, and is output to the outside through the output terminals TOUT1 and TOUT2 as a desired DC output voltage Vout.

Subsequently, the surge absorbing operation generated in the rectifying diode D41 will be described in detail by taking the rectifying diode D41 as an example.
In the initial state, voltages are induced in the secondary windings L21 and L22 of the insulating transformer T1 in such a direction that the rectifying diode D42 is biased in the reverse direction and the rectifying diode D41 is biased in the forward direction. And In this state, the voltage induced in the secondary winding L21 is rectified by the rectifying diode D41 and output to the first output terminal TOUT1 and the second output terminal TOUT2.

  When the direction of each voltage induced in the secondary windings L21 and L22 of the isolation transformer T1 is reversed in accordance with the switching operation on the primary side from the initial state, the rectifying diode D42 is forward biased and rectified. The diode D41 is biased in the reverse direction, but the rectifier diode D41 is kept on during the so-called recovery period. For this reason, an overcurrent flows through a loop composed of the secondary windings L21 and L22 of the insulating transformer T1 and the rectifying diodes D41 and D42, and the energy is accumulated in the parasitic inductor of the insulating transformer T1.

  When the recovery period elapses, the rectifying diode D41 shifts to an off state, thereby interrupting the overcurrent loop. As a result, energy accumulated in the parasitic inductor existing on the cathode side of the rectifying diode D41 during the recovery period is instantaneously released, and a surge is generated at the cathode of the rectifying diode D41. The current caused by this surge is represented by a charging path CR4 (capacitor CS41 to diode DS43 to first output terminal TOUT1 to load R to second output terminal TOUT2 to secondary winding L21 to rectifier diode D41 to capacitor CS41 shown by a dotted line in FIG. ) And the capacitor CS41 is thereby charged.

  Thereafter, the rectifying diode D41 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding of the isolation transformer T1 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CS41 is discharged from a discharge path DR4 (capacitor C41 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 to inductor LS42 to diode DS42) indicated by a one-dot chain line in FIG. ~ Capacitor CS41), thereby discharging capacitor CS41.

  Thus, according to the present embodiment, energy due to the surge generated at the cathode of the rectifying diode D41 is temporarily stored in the capacitor CS41 and then discharged to the output side via the inductor LS42. Since the phase of the discharge current at this time is delayed with respect to the phase of the voltage by the inductor LS42, the loss in the diode DS42 expressed as the product of the voltage and the current is suppressed. Similarly, the energy caused by the surge generated in one of the rectifying diodes D42 is once stored in the capacitor CS41 and then discharged to the output side through the inductor L42 with low loss.

  As a result, the surge generated in the rectifying diodes D41 and D42 is effectively absorbed (suppressed), and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

<Fifth Embodiment>
Next, a fifth embodiment corresponding to the invention according to claim 5 will be described with reference to FIG.
The switching power supply according to the present embodiment replaces the snubber circuit in the configuration of FIG. 4 according to the above-described fourth embodiment with a capacitor CS511 as a first snubber circuit for absorbing a surge generated in the rectifying diode D41. A diode DS512, an inductor LS512, and a diode DS513 are provided, and a capacitor CS521, a diode DS522, an inductor LS522, and a diode DS523 are provided as a second snubber circuit for absorbing a surge generated in the rectifying diode D42. Other configurations are the same as those of the fourth embodiment.

Here, each configuration of the snubber circuit in the fifth embodiment will be described in detail.
One electrode of the capacitor CS511 constituting the first snubber circuit is connected to the cathode of the rectifying diode D41. A diode DS513 is connected between the other electrode of the capacitor CS511 and the anode of the rectifying diode D41. That is, the anode of the diode DS513 is connected to the other electrode of the capacitor CS511, and the cathode of the diode DS513 is connected to the anode of the rectifying diode D41. The diode DS513 functions as a rectifier circuit that forms a charging path for the capacitor CS511.

  A series circuit including a diode DS512 and an inductor LS512 is connected between the other electrode of the capacitor CS511 and the anode of the rectifying diode D41. That is, the cathode of the diode DS512 is connected to the other electrode of the capacitor CS211, the anode of the diode DS512 is connected to one end of the inductor LS512, and the other end of the inductor LS512 is connected to the anode of the rectifying diode D41. . The diode DS512 and the inductor LS512 function as a rectifier circuit that forms a discharge path of the capacitor CS511.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CS521 constituting the second snubber circuit is connected to the cathode of the rectifying diode D42. A diode DS523 is connected between the other electrode of the capacitor CS521 and the anode of the rectifying diode D42. That is, the anode of the diode DS523 is connected to the other electrode of the capacitor CS521, and the cathode of the diode DS523 is connected to the anode of the rectifying diode D42. The diode DS523 functions as a rectifier circuit that forms a charging path for the capacitor CS521.

  In addition, a series circuit including a diode DS522 and an inductor LS522 is connected between the other electrode of the capacitor CS521 and the anode of the rectifying diode D42. That is, the cathode of the diode DS522 is connected to the other electrode of the capacitor CS521, the anode of the diode DS522 is connected to one end of the inductor LS522, and the other end of the inductor LS522 is connected to the anode of the rectifying diode D42. . The diode DS522 and the inductor LS522 function as a rectifier circuit that forms a discharge path of the capacitor CS521.

Next, taking the rectifying diode D42 as an example, the absorption operation of the surge generated in the rectifying diode D42 will be described in detail. Note that the normal power conversion operation is the same as that in the fourth embodiment described above, and is therefore omitted.
First, from the state in which the rectifying diode D42 is biased in the forward direction, the direction of each voltage induced in the secondary windings L21 and L22 of the insulating transformer T1 is reversed in accordance with the switching operation on the primary side, so that the rectifying diode When the diode D42 is biased in the reverse direction, the energy accumulated in the parasitic inductor in the so-called recovery period is instantaneously released as described above, and a surge is generated in the rectifying diode D42.

  In the present embodiment, the current due to the surge flows along the charging path CR5 (capacitor CS521 to diode DS523 to secondary winding L22, L21 to rectifier diode D41 to capacitor CS521) indicated by a dotted line in FIG. CS521 is charged.

  Thereafter, the rectifying diode D42 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding of the isolation transformer T1 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CS521 is discharged into the discharge path DR2 (capacitor CS521 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 to secondary winding L22 shown by a one-dot chain line in FIG. To inductor LS522 to diode DS522 to capacitor CS521), thereby discharging capacitor CS521.

  As a result, the surge generated in the rectifying diodes D41 and D42 is effectively absorbed (suppressed), and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

<Sixth Embodiment>
Next, with reference to FIG. 6, a sixth embodiment corresponding to the invention of claim 6 will be described.
The switching power supply according to the present embodiment replaces the snubber circuit in the configuration of FIG. 4 according to the above-described fourth embodiment with a capacitor CS611 as a first snubber circuit for absorbing a surge generated in the rectifying diode D41. A diode DS612, an inductor LS612, and a diode DS613 are provided, and a capacitor CS621, a diode DS622, an inductor LS622, and a diode DS623 are provided as a second snubber circuit for absorbing a surge generated in the rectifying diode D42. Other configurations are the same as those of the fourth embodiment.

Here, each configuration of the snubber circuit in the sixth embodiment will be described in detail.
One electrode of the capacitor CS611 constituting the first snubber circuit is connected to the anode of the rectifying diode D41. A diode DS613 is connected between the other electrode of the capacitor CS611 and the center tap TP. That is, the cathode of the diode DS613 is connected to the other electrode of the capacitor CS611, and the anode of the diode DS613 is connected to the center tap TP. The diode DS613 functions as a rectifier circuit that forms a charging path for the capacitor CS611.

  In addition, a series circuit including a diode DS612 and an inductor LS612 is connected between the other electrode of the capacitor CS611 and the cathode of the rectifying diode D41. That is, one end of the inductor LS612 is connected to the other electrode of the capacitor CS611, the other end of the inductor LS612 is connected to the anode of the diode DS612, and the cathode of the diode DS612 is connected to the cathode of the rectifying diode D41. The diode DS612 and the inductor LS612 function as a rectifier circuit that forms a discharge path of the capacitor CS611.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CS621 constituting the second snubber circuit is connected to the anode of the rectifying diode D42. A diode DS623 is connected between the other electrode of the capacitor CS621 and the center tap TP. That is, the cathode of the diode DS623 is connected to the other electrode of the capacitor CS621, and the anode of the diode DS623 is connected to the center tap TP. The diode DS623 functions as a rectifier circuit that forms a charging path for the capacitor CS621.

  In addition, a series circuit including a diode DS622 and an inductor LS622 is connected between the other electrode of the capacitor CS621 and the cathode of the rectifying diode D42. That is, one end of the inductor LS622 is connected to the other electrode of the capacitor CS621, the other end of the inductor LS622 is connected to the anode of the diode DS622, and the cathode of the diode DS622 is connected to the cathode of the rectifying diode D42. The diode DS622 and the inductor LS622 function as a rectifier circuit that forms a discharge path of the capacitor CS621.

Next, taking the rectifying diode D42 as an example, the absorption operation of the surge generated in the rectifying diode D42 will be described in detail. Note that the normal power conversion operation is the same as that in the fourth embodiment described above, and is therefore omitted.
First, from the state in which the rectifying diode D42 is biased in the forward direction, the direction of each voltage induced in the secondary windings L21 and L22 of the insulating transformer T1 is reversed in accordance with the switching operation on the primary side, so that the rectifying diode When the diode D42 is biased in the reverse direction, the energy accumulated in the parasitic inductor during the so-called recovery period is instantaneously released as described above, and a positive surge is generated at the cathode of the rectifying diode D42. This is equivalent to a negative surge being applied to the anode of the rectifying diode D42. In the present embodiment, the negative surge is absorbed to absorb the surge generated in the rectifying diode D42. .

  The current due to the negative surge described above flows along the charging path CR6 (capacitor CS621 to secondary winding L22 to diode DS623 to capacitor CS621) indicated by a dotted line in FIG. 6, and thereby the capacitor CS621 is charged.

  Thereafter, the rectifying diode D42 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding of the isolation transformer T1 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CS621 is discharged from the discharge path DR6 (capacitor CS621 to inductor LS622 to diode DS622 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 shown by a one-dot chain line in FIG. ~ Secondary winding L22 ~ capacitor CS621), thereby discharging the capacitor CS621.

  As a result, the surge generated in the rectifying diodes D41 and D42 is effectively absorbed (suppressed), and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

<Seventh embodiment>
With reference to FIG. 7, a seventh embodiment corresponding to the seventh aspect of the present invention will be described.
FIG. 7 shows a configuration of the switching power supply device according to the present embodiment. The configuration on the primary side of the insulation transformer T7 in the figure is the same as the primary side of the insulation transformer T in the conventional device shown in FIG. 15, and in FIG. Omitted.

  As shown in FIG. 7, this switching power supply device includes an insulating transformer T7, and a secondary wave (output side) on its secondary side (output side) includes a full-wave rectifier circuit including rectifier diodes D71, D72, D73, and D74, and an output. A smoothing circuit comprising an inductor Lout and an output capacitor Cout is connected. Here, the cathodes of the rectifying diodes D71 and D73 serve as the first output section of the full-wave rectifier circuit and are connected to the first output terminal TOUT1 via the output inductor Lout. The anodes of the rectifying diodes D72 and D74 serve as the second output unit of the full-wave rectifier circuit and are commonly connected to the second output terminal TOUT1.

  The anode of the rectifying diode D71 is connected to the cathode of the rectifying diode D72, and these connection points serve as the first input portion of the full-wave rectifier circuit. The anode of the rectifier diode D73 is connected to the cathode of the rectifier diode D74, and these connection points serve as the second input portion of the full-wave rectifier circuit. One end and the other end of the secondary winding L2 of the isolation transformer T7 are connected to the first and second input portions of the full-wave rectifier circuit, respectively. A load R fed by the switching power supply device is connected between the output terminal TOUT1 and the output terminal TOUT2.

  The switching power supply apparatus includes a capacitor CS711, a diode DS712, an inductor LS712, and a diode DS713 as a first snubber circuit for absorbing a surge generated at the cathode of the rectifying diode D72, and the cathode of the rectifying diode D74. A capacitor CS721, a diode DS722, an inductor LS722, and a diode DS723 are provided as a second snubber circuit for absorbing the surge generated in the capacitor.

Here, each configuration of the snubber circuit will be described in detail.
One electrode of the capacitor CS711 constituting the first snubber circuit is connected to the cathode of the rectifier diode D72, that is, the second input portion of the full-wave rectifier circuit. A diode DS713 is connected between the other electrode of the capacitor CS711 and the first input portion of the full-wave rectifier circuit. Specifically, the cathode of the diode DS713 is connected to the other electrode of the capacitor CS711, and the anode of the diode DS713 is connected to the cathode of the rectifying diode D72. The diode DS713 functions as a rectifier circuit that forms a charging path for the capacitor CS711.

  A series circuit including a diode DS712 and an inductor LS712 is connected between the other electrode of the capacitor CS711 and the first input portion of the full-wave rectifier circuit. That is, the anode of the diode DS712 is connected to the other electrode of the capacitor CS711, one end of the inductor LS712 is connected to the cathode of the diode DS712, and the other end of the inductor LS712 is the first of the full-wave rectifier circuit. Connected to the input section. The inductor LS712 and the diode DS712 function as a rectifier circuit that forms a discharge path of the capacitor CS711.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CS721 constituting the second snubber circuit is connected to the cathode of the rectifier diode D72, that is, the first input portion of the full-wave rectifier circuit. A diode DS723 is connected between the other electrode of the capacitor CS721 and the second input portion of the full-wave rectifier circuit. Specifically, the cathode of the diode DS723 is connected to the other electrode of the capacitor CS721, and the anode of the diode DS723 is connected to the cathode of the rectifying diode D74. The diode DS723 functions as a rectifier circuit that forms a charging path for the capacitor CS721.

A series circuit including a diode DS722 and an inductor LS722 is connected between the other electrode of the capacitor CS721 and the second input portion of the full-wave rectifier circuit. That is, the anode of the diode DS722 is connected to the other electrode of the capacitor CS721, and one end of the inductor LS722 is connected to the cathode of the diode DS722. The other end of the inductor LS722 is connected to the second wave of the full-wave rectifier circuit. Connected to the input section. The inductor LS722 and the diode DS722 function as a rectifier circuit that forms a discharge path of the capacitor CS721.
The configuration on the primary side of the insulating transformer T7 is the same as that of the conventional device shown in FIG. 15, and the description thereof is omitted.

Next, the operation of the present switching power supply device will be described.
First, a normal power conversion operation will be briefly described. In FIG. 15 to be used, the switching circuit composed of the switches S1 to S4 performs a predetermined switching operation (known switching operation), whereby the DC input voltage Vin is converted into an AC voltage, and the insulation transformer T7 shown in FIG. To the primary winding L1. As a result, an AC voltage is induced in the secondary winding L2 of the insulating transformer T7. The AC voltage induced in the secondary winding L2 is full-wave rectified by rectifying diodes D71, D72, D73, and D74. The full-wave rectified voltage is smoothed by the output inductor Lout and the output capacitor Cout, and is supplied as a desired DC output voltage Vout to the external load R through the output terminals TOUT1 and TOUT2.

Subsequently, the surge absorbing operation generated at the cathode of the rectifying diode D72 will be described in detail by taking the rectifying diode D72 as an example.
In an initial state, a voltage is induced in the secondary winding L2 of the isolation transformer T7 in such a direction that the rectifying diodes D72 and D73 are biased in the forward direction and the rectifying diodes D71 and D74 are biased in the reverse direction. It shall be. In this state, the voltage induced in the secondary winding L2 is rectified by the rectifying diodes D72 and D73 and output to the first output terminal TOUT1 and the second output terminal TOUT2.

  When the direction of the voltage induced in the secondary winding L2 of the insulation transformer T7 is reversed in accordance with the switching operation on the primary side from the initial state, the rectifying diodes D72 and D73 are biased in the reverse direction, The rectifying diodes D71 and D74 are biased in the forward direction, but the rectifying diodes D72 and D73 are kept on during the so-called recovery period. For this reason, an overcurrent flows through a loop composed of the secondary winding L2, the rectifying diode D72, and the rectifying diode D74 of the insulating transformer T7, and the energy is accumulated in the parasitic inductor of the insulating transformer T7.

  When the recovery period elapses, the rectifying diode D72 shifts to an off state, thereby interrupting the overcurrent loop. As a result, energy accumulated in the parasitic inductor existing on the cathode side of the rectifying diode D72 during the recovery period is instantaneously released, and a surge is generated at the cathode of the rectifying diode D72. The current due to this surge flows along a charging path CR7 (capacitor CS711 to secondary winding L2 to diode DS713 to capacitor CS711) indicated by a dotted line in FIG. 7, and thereby the capacitor CS711 is charged.

  Thereafter, the rectifying diode D72 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding L2 of the isolation transformer T7 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CS721 is discharged from the discharge path DR7 (capacitor CS711 to diode DS712 to inductor LS712 to rectifier diode D71 to output inductor Lout to first output terminal TOUT1 to load R to It flows along the second output terminal TOUT2, the rectifying diode D74, and the capacitor CS711), whereby the capacitor CS721 is discharged.

  Thus, according to the present embodiment, the energy caused by the surge generated at the cathode of the rectifying diode D72 is temporarily stored in the capacitor CS711 and then discharged to the output side via the inductor LS712. Since the phase of the discharge current at this time is delayed with respect to the phase of the voltage by the inductor LS712, the loss in the diode DS712 expressed as the product of the voltage and the current is suppressed. Similarly, the energy generated by the surge generated in the rectifying diode D74 is temporarily stored in the capacitor CS721 and then discharged to the output side through the inductor LS722 with low loss.

  Thus, the surge generated on the cathode side of the rectifying diodes D72 and D74, that is, the input part of the full-wave rectifier circuit is effectively absorbed (suppressed) and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

<Eighth Embodiment>
Next, with reference to FIG. 8, an eighth embodiment corresponding to the eighth aspect of the present invention will be described.
The switching power supply according to this embodiment includes a capacitor as a snubber circuit for absorbing the surge generated at the cathodes of the rectifying diodes D71 and D73, instead of the snubber circuit in the configuration of FIG. 7 according to the seventh embodiment. CS81, diode DS82, inductor LS82, and diode DS83 are provided. Other configurations are the same as those of the seventh embodiment.

Here, the configuration of the snubber circuit in the eighth embodiment will be described in detail.
One electrode of the capacitor CS81 constituting the snubber circuit is connected to the cathodes of the rectifying diodes D71 and D73, that is, the first output portion of the full-wave rectifier circuit. A diode DS83 is connected between the other electrode of the capacitor CS81 and the first output terminal TOUT1. That is, the anode of the diode DS83 is connected to the other electrode of the capacitor CS81, and the cathode of the diode DS83 is connected to the first output terminal TOUT1. The diode DS83 functions as a rectifier circuit that forms a charging path for the capacitor CS81.

  In addition, a series circuit including the diode DS82 and the inductor LS82 is connected between the other electrode of the capacitor CS81 and the second output terminal TOUT2. That is, the cathode of the diode DS82 is connected to the other electrode of the capacitor CS81, the anode of the diode DS82 is connected to one end of the inductor LS82, and the other end of the inductor LS82 is connected to the second output terminal TOUT2. The diode DS82 and the inductor LS82 function as a rectifier circuit that forms a discharge path of the capacitor CS81.

Next, taking the rectifying diode D71 as an example, the absorption operation of the surge generated in the rectifying diode D71 will be described in detail. Note that the normal power conversion operation is the same as in the seventh embodiment described above, and is therefore omitted.
First, from the state where the rectifying diode D71 is biased in the forward direction and the rectifying diode D72 is biased in the reverse direction, it is induced in the secondary winding L2 of the isolation transformer T7 in accordance with the switching operation on the primary side. When the direction of the voltage is reversed, the rectifying diode D71 is biased in the reverse direction, and the rectifying diode D73 is biased in the forward direction, as described above, it accumulates in the parasitic inductor. The generated energy is instantaneously released, and a surge is generated at the cathode of the rectifying diode D71.

  In this embodiment, the current caused by the surge is represented by a charging path CR8 (capacitor CS81 to diode DS83 to first output terminal TOUT1 to load R to second output terminal TOUT2 to rectifying diode D74 to secondary winding indicated by a dotted line in FIG. L2 flows along the rectifying diode D71 to the capacitor CS81), thereby charging the capacitor CS81.

  Thereafter, the rectifying diode D71 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding L2 of the isolation transformer T7 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CS81 is discharged from the discharge path DR8 (capacitor CS81 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 to inductor LS82 to diode DS82) indicated by a one-dot chain line in FIG. ~ Capacitor CS81), thereby discharging the capacitor CS81.

  Thus, the surge generated on the cathode side of the rectifying diodes D71 and D73, that is, the output part of the full-wave rectifier circuit is effectively absorbed (suppressed), and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

<Ninth Embodiment>
Next, a ninth embodiment of the present invention will be described in claim 9 of the present application with reference to FIG.
The switching power supply according to this embodiment includes a capacitor as a snubber circuit for absorbing the surge generated at the cathodes of the rectifying diodes D71 and D73, instead of the snubber circuit in the configuration of FIG. 7 according to the seventh embodiment. CS91, diode DS912, DS922, inductor LS912, LS922, and diode DS93 are provided. Other configurations are the same as those of the seventh embodiment.

Here, the configuration of the snubber circuit in the ninth embodiment will be described in detail.
One electrode of the capacitor CS91 constituting the snubber circuit is connected to the cathodes of the rectifying diodes D71 and D73, that is, the first output portion of the full-wave rectifier circuit. A diode DS93 is connected between the other electrode of the capacitor CS91 and the first output terminal TOUT1. That is, the anode of the diode DS93 is connected to the other electrode of the capacitor CS91, and the cathode of the diode DS93 is connected to the first output terminal TOUT1. The diode DS93 functions as a rectifier circuit that forms a charging path for the capacitor CS91.

  A series circuit including a diode DS912 and an inductor LS912 is connected between the other electrode of the capacitor CS91 and the second input portion of the full-wave rectifier circuit. That is, the cathode of the diode DS912 is connected to the other electrode of the capacitor CS91, the anode of the diode DS912 is connected to one end of the inductor LS912, and the other end of the inductor LS912 is the second input part of the full-wave rectifier circuit. (Connected to the cathode of the rectifying diode D74).

A series circuit including a diode DS922 and an inductor LS922 is connected between the other electrode of the capacitor CS91 and the first input portion of the full-wave rectifier circuit. That is, the cathode of the diode DS922 is connected to the other electrode of the capacitor CS91, the anode of the diode DS922 is connected to one end of the inductor LS922, and the other end of the inductor LS922 is the first input part of the full-wave rectifier circuit. (Connected to the cathode of the rectifying diode D72). The diode DS912 and the inductor LS912 and the diode DS922 and the inductor LS922 function as a rectifier circuit that forms a discharge path of the capacitor CS91.

Next, taking the rectifying diode D71 as an example, the absorption operation of the surge generated in the rectifying diode D71 will be described in detail. Note that the normal power conversion operation is the same as that of the seventh embodiment described above, and is therefore omitted.
First, from the state where the rectifying diodes D71 and D74 are biased in the forward direction and the rectifying diodes D72 and D73 are biased in the reverse direction, the secondary winding L2 of the isolation transformer T7 is accompanied by the switching operation on the primary side. When the rectifying diode D71 is biased in the reverse direction, the energy stored in the parasitic inductor is instantaneously released during the so-called recovery period, and the surge Is generated at the cathode of the rectifying diode D71.

  In this embodiment, the current caused by the surge is represented by a charging path CR9 (capacitor CS91 to diode DS93 to first output terminal TOUT1 to load R to second output terminal TOUT2 to rectifying diode D74 to secondary winding shown by a dotted line in FIG. L2 flows along the rectifying diode D71 to the capacitor CS91), whereby the capacitor CS91 is charged.

  Thereafter, the rectifying diode D71 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding L2 of the isolation transformer T7 with the switching operation on the primary side. In this case, the charge accumulated in the capacitor CS91 is discharged from the discharge path DR9 (capacitor CS91 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 to rectifier diode D74 to Flows along the inductor LS912-diode DS912-capacitor CS91), whereby the capacitor CS91 is discharged.

Thus, the surge generated at the cathode of the rectifying diode D71, that is, the output portion of the full-wave rectifier circuit is effectively absorbed by the capacitor CS91, and the energy is released to the output side through the inductor LS912. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.
The surge generated at the cathode of the rectifying diode D73 is absorbed by the capacitor CS91 and then discharged to the output side via the inductor LS922.

  In the example shown in FIG. 9, the rectifier circuit including the diode DS912 and the inductor LS912 and the rectifier circuit including the diode DS922 and the inductor LS922 are provided as the discharge path of the capacitor CS91. However, as illustrated in FIGS. Any one of them may be provided. Here, the example shown in FIG. 10 includes only the diode DS912 and the inductor LS912 as the discharge path of the capacitor CS91. In this case, surges generated at the cathodes of the rectifier diode D71 and the rectifier diode D73 are temporarily stored in the capacitor CS91 and then discharged to the output side via the diode DS912 and the inductor LS912. The example shown in FIG. 11 includes a diode DS922 and an inductor LS922 as a discharge path of the capacitor CS91. Similarly in this example, the surge accumulated in the capacitor CS91 is discharged to the output side via the diode DS922 and the inductor LS922 path.

<Tenth Embodiment>
With reference to FIG. 12, a tenth embodiment corresponding to the invention of claim 10 will be described.
FIG. 12 shows the configuration of the switching power supply according to this embodiment. The configuration on the primary side of the insulation transformer T7 in the figure is the same as the primary side of the insulation transformer T in the conventional device shown in FIG. 15, and in FIG. Omitted.

  As shown in FIG. 12, this switching power supply apparatus has a smoothing circuit comprising a full-wave rectifier circuit comprising rectifying diodes D71, D72, D73, and D74, an output inductor Lout, and an output capacitor Cout on the output side of the isolation transformer T7. The circuit is connected. Here, the cathodes of the rectifying diodes D71 and D73 serve as the first output section of the full-wave rectifier circuit and are connected to the first output terminal TOUT1 via the output inductor Lout. The anodes of the rectifying diodes D72 and D74 are used as the second output unit of the full-wave rectifier circuit and are commonly connected to the second output terminal TOUT1.

  The anode of the rectifying diode D71 is connected to the cathode of the rectifying diode D72, and these connection points serve as the first input portion of the full-wave rectifier circuit. The anode of the rectifying diode D73 is connected to the cathode of the rectifying diode D74, and these connection points serve as the second input portion of the full-wave rectifier circuit. One end and the other end of the secondary winding L2 of the isolation transformer T7 are connected to the first and second input portions of the full-wave rectifier circuit, respectively. A load R fed by the switching power supply device is connected between the output terminal TOUT1 and the output terminal TOUT2.

  In addition, the switching power supply device includes a capacitor CSA11, a diode DSA12, an inductor LSA12, and a diode DSA13 as a first snubber circuit for absorbing a surge generated at the cathode of the rectifying diode D72, and the cathode of the rectifying diode D74. A capacitor CSA21, a diode DSA22, an inductor LSA22, and a diode DSA23 are provided as a second snubber circuit for absorbing a surge generated in the capacitor.

Here, each configuration of the snubber circuit will be described in detail.
One electrode of the capacitor CSA11 constituting the first snubber circuit is connected to the cathode of the rectifier diode D74, that is, the second input portion of the full-wave rectifier circuit. A diode DSA13 is connected between the other electrode of the capacitor CSA11 and the first output terminal TOUT1. Specifically, the anode of the diode DSA13 is connected to the other electrode of the capacitor CSA11, and the cathode of the diode DSA13 is connected to the first output terminal TOUT1. The diode DSA13 functions as a rectifier circuit that forms a charging path for the capacitor CSA11.

  In addition, a series circuit including a diode DSA12 and an inductor LSA12 is connected between the other electrode of the capacitor CSA11 and the second output terminal TOUT2. That is, the cathode of the diode DSA12 is connected to the other electrode of the capacitor CSA11, one end of the inductor LSA12 is connected to the anode of the diode DSA12, and the other end of the inductor LSA12 is connected to the second output terminal TOUT2. The The inductor LSA12 and the diode DSA12 function as a rectifier circuit that forms a discharge path of the capacitor CSA11.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CSA21 constituting the second snubber circuit is connected to the cathode of the rectifier diode D72, that is, the first input portion of the full-wave rectifier circuit. A diode DSA23 is connected between the other electrode of the capacitor CSA21 and the first output terminal TOUT1. Specifically, the anode of the diode DSA23 is connected to the other electrode of the capacitor CSA21, and the cathode of the diode DSA23 is connected to the first output terminal TOUT1. The diode DSA23 functions as a rectifier circuit that forms a charging path for the capacitor CSA21.

A series circuit including a diode DSA22 and an inductor LSA22 is connected between the other electrode of the capacitor CSA21 and the second output terminal TOUT2. That is, the cathode of the diode DSA22 is connected to the other electrode of the capacitor CSA21, one end of the inductor LSA22 is connected to the anode of the diode DSA22, and the other end of the inductor LSA22 is connected to the second output terminal TOUT2. The The inductor LSA22 and the diode DSA22 function as a rectifier circuit that forms a discharge path of the capacitor CSA21.
The configuration on the primary side of the insulating transformer T7 is the same as that of the conventional device shown in FIG. 15, and the description thereof is omitted.

Next, taking the rectifying diode D74 as an example, the absorption operation of the surge generated at the cathode of the rectifying diode D74 will be described in detail. The normal power conversion operation is the same as that in the seventh to ninth embodiments described above, and is therefore omitted.
In an initial state, a voltage is induced in the secondary winding L2 of the insulating transformer T7 in such a direction that the rectifying diodes D71 and D74 are forward biased and the rectifying diodes D72 and D73 are biased in the reverse direction. Shall. In this state, the voltage induced in the secondary winding L2 is rectified by the rectifying diodes D71 and D74 and output to the first output terminal TOUT1 and the second output terminal TOUT2.

  When the direction of the voltage induced in the secondary winding L2 of the insulation transformer T7 is reversed in accordance with the switching operation on the primary side from the initial state, the rectifying diodes D71 and D74 are biased in the reverse direction, The rectifying diodes D72 and D73 are biased in the forward direction, but the rectifying diode D74 is kept on during the so-called recovery period. For this reason, an overcurrent flows through a loop composed of the secondary winding L2, the rectifying diode D72, and the rectifying diode D74 of the insulating transformer T7, and the energy is accumulated in the parasitic inductor.

  When the recovery period elapses, the rectifying diode D74 shifts to an off state, thereby interrupting the overcurrent loop. As a result, the energy accumulated in the parasitic inductor existing on the cathode side of the rectifying diode D74 is instantaneously released, and a surge is generated at the cathode of the rectifying diode D74. The current caused by this surge is represented by a charging path CR12 (capacitor CSA21 to diode DSA23 to first output terminal TOUT1 to load R to second output terminal TOUT2 to rectifier diode D74 to secondary winding L2 to capacitor CSA21 indicated by a dotted line in FIG. ) And the capacitor CSA21 is thereby charged.

  Thereafter, the rectifying diode D74 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding L2 of the isolation transformer T7 with the switching operation on the primary side. In this case, the electric charge accumulated in the capacitor CSA21 is discharged from the discharge path DR12 (capacitor CSA21 to rectifier diode D71 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 to each other as indicated by a one-dot chain line in FIG. It flows along the inductor LSA22 to the diode DSA22 to the capacitor CSA21), whereby the capacitor CSA21 is discharged.

  Thus, according to the present embodiment, the energy caused by the surge generated at the cathode of the rectifying diode D74 is temporarily stored in the capacitor CSA21 and then discharged to the output side through the inductor LSA22. Since the phase of the discharge current at this time is delayed with respect to the phase of the voltage by the inductor LSA22, the loss in the diode DSA22 expressed as the product of the voltage and the current is suppressed. Similarly, the energy generated by the surge generated in the rectifying diode D72 is temporarily stored in the capacitor CSA11 and then discharged to the output side through the inductor LSA12 with low loss.

  Thus, the surge generated on the cathode side of the rectifying diodes D72 and D74, that is, the input part of the full-wave rectifier circuit is effectively absorbed (suppressed) and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

  In the example shown in FIG. 12, the rectifier circuit including the diode DSA12 and the inductor LSA12 is provided as the discharge path of the capacitor CSA11, and the rectifier circuit including the diode DSA22 and the inductor LSA22 is provided as the discharge path of the capacitor CSA21. As shown in FIG. 13, the two inductors LSA12 and LSA22 shown in FIG. 12 may be replaced with one inductor LSA2, and one inductor LSA2 may be shared as the discharge path of the capacitors CSA11 and CSA21. Specifically, in the example shown in FIG. 13, in the configuration shown in FIG. 12, an inductor LSA2 is provided instead of the inductors LSA12 and LSA22, and each anode of the diodes DSA12 and DSA22 is connected to one end of the inductor LSA2, and this inductor LSA2 Is connected to the second output terminal TOUT2.

  According to the example shown in FIG. 13, the discharge path DR13 of the capacitor CSA21 includes the capacitor CSA21, the rectifying diode D71, the output inductor Lout, the first output terminal TOUT1, the load R, the second output terminal TOUT2, the inductor LSA2, and the diode DSA22. The path of the capacitor CSA21 is formed. The discharge path of the capacitor CSA11 includes the capacitor CSA11, the rectifying diode D73, the output inductor Lout, the first output terminal TOUT1, the load R, the second output terminal TOUT2, the inductor LSA2, and the diode DSA12. It is formed from the path of the capacitor CSA11. The charging path is the same as that shown in FIG.

<Eleventh embodiment>
Next, an eleventh embodiment corresponding to the invention of claim 11 will be described with reference to FIG.
The switching power supply according to the present embodiment replaces the snubber circuit in the configuration of FIG. 12 according to the above-described tenth embodiment with a capacitor as a first snubber circuit for absorbing a surge generated at the cathode of the rectifying diode D72. A CSA 11, a diode DSB 12, an inductor LSB 12, and a diode DSA 13 are provided, and a capacitor CSA 21, a diode DSB 22, an inductor LSB 22, and a diode DSA 23 are provided as a second snubber circuit for absorbing a surge generated at the cathode of the rectifying diode D 74.

Here, each configuration of the snubber circuit will be described in detail.
One electrode of the capacitor CSA11 constituting the first snubber circuit is connected to the cathode of the rectifier diode D74, that is, the second input portion of the full-wave rectifier circuit. A diode DSA13 is connected between the other electrode of the capacitor CSA11 and the first output terminal TOUT1. Specifically, the anode of the diode DSA13 is connected to the other electrode of the capacitor CSA11, and the cathode of the diode DSA13 is connected to the first output terminal TOUT1. The diode DSA13 functions as a rectifier circuit that forms a charging path for the capacitor CSA11.

  A series circuit including a diode DSB12 and an inductor LSB12 is connected between the other electrode of the capacitor CSA11 and the first input portion of the full-wave rectifier circuit. That is, the cathode of the diode DSB12 is connected to the other electrode of the capacitor CSA11, one end of the inductor LSB12 is connected to the anode of the diode DSB12, and the other end of the inductor LSB12 is the first input of the full-wave rectifier circuit. Connected to the part. The inductor LSB12 and the diode DSB12 function as a rectifier circuit that forms a discharge path of the capacitor CSA11.

  One second snubber circuit is similarly configured. That is, one electrode of the capacitor CSA21 constituting the second snubber circuit is connected to the cathode of the rectifier diode D72, that is, the first input portion of the full-wave rectifier circuit. A diode DSA23 is connected between the other electrode of the capacitor CSA21 and the first output terminal TOUT1. Specifically, the anode of the diode DSA23 is connected to the other electrode of the capacitor CSA21, and the cathode of the diode DSA23 is connected to the first output terminal TOUT1. The diode DSA23 functions as a rectifier circuit that forms a charging path for the capacitor CSA21.

A series circuit including a diode DSB22 and an inductor LSB22 is connected between the other electrode of the capacitor CSA21 and the second input portion of the full-wave rectifier circuit. That is, the cathode of the diode DSB22 is connected to the other electrode of the capacitor CSA21, and one end of the inductor LSB22 is connected to the anode of the diode DSB22. The other end of the inductor LSB22 Connected to the input section. The inductor LSB22 and the diode DSB22 function as a rectifier circuit that forms a discharge path of the capacitor CSA21.
The configuration on the primary side of the insulating transformer T7 is the same as that of the conventional device shown in FIG. 15, and the description thereof is omitted.

Next, the surge absorbing operation generated at the cathode of the rectifying diode D74 will be described in detail by taking the rectifying diode D74 as an example. Since the power conversion operation is the same as that in the tenth embodiment described above, this is omitted.
First, when the rectifying diodes D71 and D74 change from the forward biased state to the reverse biased state, as described above, the energy accumulated in the parasitic inductor in the so-called recovery period is instantaneously released, A surge is generated at the cathode of the rectifying diode D74.

  In the present embodiment, the current caused by the surge is represented by a charging path CR14 (capacitor CSA21 to diode DSA23 to first output terminal TOUT1 to load R to second output terminal TOUT2 to rectifier diode D74 to secondary winding shown by a dotted line in FIG. L2-capacitor CSA21), thereby charging capacitor CSA21.

  Thereafter, the rectifying diode D74 is forward-biased in the process of reversing the direction of the voltage induced in the secondary winding L2 of the isolation transformer T7 with the switching operation on the primary side. In this case, the charge accumulated in the capacitor CSA21 is discharged from the discharge path DR14 (capacitor CSA21 to rectifier diode D71 to output inductor Lout to first output terminal TOUT1 to load R to second output terminal TOUT2 to each other as indicated by a one-dot chain line in FIG. It flows along the rectifying diode D74, the inductor LSB22, the diode DSB22, and the capacitor CSA21), whereby the capacitor CSA21 is discharged.

  Thus, according to the present embodiment, the energy due to the surge generated at the cathode of the rectifying diode D74 is temporarily stored in the capacitor CSA21 and then discharged to the output side via the inductor LSB22. Since the phase of the discharge current at this time is delayed with respect to the phase of the voltage by the inductor LSB22, the loss in the diode DSB22 expressed as the product of the voltage and the current is suppressed. Similarly, energy due to the surge generated in the rectifying diode D72 is temporarily stored in the capacitor CSA11 and then discharged to the output side through the inductor LSB12 with low loss.

  Thus, the surge generated on the cathode side of the rectifying diodes D72 and D74, that is, the input part of the full-wave rectifier circuit is effectively absorbed (suppressed) and the energy is released to the output side. Therefore, the rectifying diode can be protected from the surge without reducing the power supply efficiency.

As mentioned above, although embodiment of this invention was explained in full detail, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, in the first to third embodiments described above, a snubber circuit is provided for each of the rectifying diodes D1 and D2. However, if necessary, a snubber circuit may be provided for one of the rectifying diodes. Good. Similarly, in the fifth and sixth embodiments described above, a snubber circuit is provided for each of the rectifying diodes D41 and D42. However, if necessary, a snubber circuit is provided for any one of the rectifying diodes. Also good. Similarly, in the seventh, tenth, and eleventh embodiments described above, a snubber circuit is provided for each of the rectifying diodes D72 and D74. However, if necessary, a snubber circuit is provided for one of the rectifying diodes. It may be provided.

In the above-described embodiment, the half bridge type is adopted as the primary side switching circuit of the isolation transformer. However, the present invention is not limited to this, and any type of switching circuit such as a full bridge type may be adopted. it can. The rectifier circuit on the secondary side of the isolation transformer is not limited to the above-described embodiment, and any capacitor can be provided as long as it is possible to provide a capacitor charging path and a discharging path for absorbing a surge. A type of circuit can be employed.
In the above-described embodiment, the rectifier diode is employed as the rectifier element. However, the present invention is not limited to this, and for example, a thyristor or a power transistor can be employed.

1 is a circuit diagram of a switching power supply device according to a first embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 2nd embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 3rd embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 4th embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 5th embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 6th embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 7th embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning an 8th embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 9th embodiment of the present invention. It is a circuit diagram of the 1st modification of the switching power supply device concerning a 9th embodiment of the present invention. It is a circuit diagram of the 2nd modification of the switching power supply device concerning a 9th embodiment of the present invention. It is a circuit diagram of the switching power supply device concerning a 10th embodiment of the present invention. It is a circuit diagram of the modification of the switching power supply device which concerns on 10th Embodiment of this invention. It is a circuit diagram of the switching power supply device which concerns on 11th Embodiment of this invention. It is a circuit diagram of the switching power supply device which concerns on a prior art. It is a waveform diagram of a surge.

Explanation of symbols

  T1, T7; insulation transformer, D1, D2, D41, D42, D71, D72, D73, D74; rectifier diode, Lout; output inductor, Cout; output capacitor, TIN1, TIN2; input terminal, TOUT1, TOUT2; Output terminal, CS11, CS21, CS211, CS221, CS311, CS321, CS41, CS511, CS521, CS611, CS621, CS711, CS721, CS81, CS91, CSA11, CSA21; capacitor, DS12, DS22, DS13, DS23, DS212, DS222 , DS213, DS223, DS312, DS322, DS313, DS323, DS42, DS43, DS512, DS522, DS513, DS523, DS612, DS622, DS61 , DS623, DS712, DS722, DS713, DS723, DS82, DS83, DS912, DS922, DS93, DSA12, DSA22, DSA13, DSA23, DSB12, DSB22, DSB13, DSB23; diode, LS12, LS22, LS212, LS222, LS312, LS322 , LS42, LS512, LS522, LS612, LS622, LS712, LS723, LS82, LS912, LS922, LSA12, LSA22, LSA2, LSB12, LSB22; inductor.

Claims (11)

An insulating transformer having a center tap provided on the secondary side, the center tap being connected to a first terminal via an output inductor, and first and second terminals at one end and the other end of the secondary winding of the insulating transformer; In the switching power supply device in which the output terminals of the rectifying elements are connected to each other, and the input terminals of the first and second rectifying elements are commonly connected to the second terminal.
A capacitor having one electrode connected to the output terminal of the first or second rectifying element;
A first rectifier circuit connected between the other electrode of the capacitor and the first terminal to form a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a discharge path of the capacitor;
A switching power supply device comprising: An insulating transformer provided with a center tap on the secondary side, and the output terminals of the first and second rectifying elements are connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device in which the input terminals of the two rectifier elements are commonly connected to the second terminal,
A capacitor having one electrode connected to the output terminal of the first or second rectifying element;
A first rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a discharge path of the capacitor;
A switching power supply device comprising: An insulating transformer provided with a center tap on the secondary side, and the output terminals of the first and second rectifying elements are connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device in which the input terminals of the two rectifier elements are commonly connected to the second terminal,
A capacitor having one electrode connected to the output terminal of the first or second rectifying element;
A first rectifier circuit connected between the other electrode of the capacitor and the center tap and forming a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a discharge path of the capacitor;
A switching power supply device comprising: An insulating transformer provided with a center tap on the secondary side, and each input terminal of the first and second rectifying elements is connected to one end and the other end of the secondary winding of the insulating transformer, respectively. In the switching power supply device in which the output terminal of the two rectifying elements is commonly connected to the first terminal via the output inductor, and the center tap is connected to the second terminal,
A capacitor having one electrode connected to the output terminal of the first or second rectifying element;
A first rectifier circuit connected between the other electrode of the capacitor and the first terminal to form a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a discharge path of the capacitor;
A switching power supply device comprising: In a switching power supply comprising an insulating transformer having a center tap on the secondary side, and having the input terminals of the first and second rectifying elements connected to one end and the other end of the secondary winding of the insulating transformer, respectively ,
A capacitor having one electrode connected to the output terminal of the first or second rectifying element;
A first rectifier circuit connected between the other electrode of the capacitor and an input terminal of the first or second rectifying element and forming a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and an input terminal of the first or second rectifier element and forming a discharge path of the capacitor;
A switching power supply device comprising: In a switching power supply comprising an insulating transformer having a center tap on the secondary side, and having the input terminals of the first and second rectifying elements connected to one end and the other end of the secondary winding of the insulating transformer, respectively ,
A capacitor having one electrode connected to an input terminal of the first or second rectifying element;
A first rectifier circuit connected between the other electrode of the capacitor and the center tap and forming a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the output terminal of the first or second rectifier element and forming a discharge path of the capacitor;
A switching power supply device comprising: In the switching power supply device in which one end and the other end of the secondary winding of the isolation transformer are connected to the first and second input parts of the full-wave rectifier circuit, respectively.
A capacitor having one electrode connected to the first input of the full-wave rectifier circuit;
A first rectifier circuit connected between the other electrode of the capacitor and a second input portion of the full-wave rectifier circuit and forming a charge path for the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and a second input portion of the full-wave rectifier circuit and forming a discharge path of the capacitor;
A switching power supply device comprising: One end and the other end of the secondary winding of the isolation transformer are respectively connected to the first and second input portions of the full-wave rectifier circuit, and the first output portion of the full-wave rectifier circuit is connected to the first terminal via the output inductor. In the switching power supply device, wherein the second output portion of the full-wave rectifier circuit is connected to the second terminal.
A capacitor having one electrode connected to the first output of the full-wave rectifier circuit;
A first rectifier circuit connected between the other electrode of the capacitor and the first terminal to form a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a discharge path of the capacitor;
A switching power supply device comprising: One end and the other end of the secondary winding of the isolation transformer are respectively connected to the first and second input portions of the full-wave rectifier circuit, and the first output portion of the full-wave rectifier circuit is connected to the first terminal via the output inductor. In the connected switching power supply device,
A capacitor having one electrode connected to the first output of the full-wave rectifier circuit;
A first rectifier circuit connected between the other electrode of the capacitor and the first terminal to form a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the first or second input terminal of the full-wave rectifier circuit and forming a discharge path of the capacitor;
A switching power supply device comprising: One end and the other end of the secondary winding of the isolation transformer are respectively connected to the first and second input portions of the full-wave rectifier circuit, and the first output portion of the full-wave rectifier circuit is connected to the first terminal via the output inductor. In the switching power supply device, wherein the second output portion of the full-wave rectifier circuit is connected to the second terminal.
A capacitor having one electrode connected to the first or second input of the full-wave rectifier circuit;
A first rectifier circuit connected between the other electrode of the capacitor and the first terminal to form a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the second terminal and forming a discharge path of the capacitor;
A switching power supply device comprising: In the switching power supply device in which one end and the other end of the secondary winding of the isolation transformer are connected to the first and second input parts of the full-wave rectifier circuit, respectively.
A capacitor having one electrode connected to one of the first and second input portions of the full-wave rectifier circuit;
A first rectifier circuit connected between the other electrode of the capacitor and the first terminal to form a charging path of the capacitor;
A second rectifier circuit connected between the other electrode of the capacitor and the other of the first and second input parts and forming a discharge path of the capacitor;
A switching power supply device comprising:

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