JP2019041534A - Dc-dc converter and power supply method - Google Patents

Abstract

To provide a DC-DC converter capable of achieving an easy large current output and stable power supply at an optional output voltage.SOLUTION: The DC-DC converter includes: a tank capacitor CT, a bucket capacitor CB and a source capacitor CS arranged between an input-output line 5 between an input terminal 2 and an output terminal 4 and a common line 6. The bucket capacitor CB has a smaller capacity than the tank capacitor CT and the source capacitor CS. The bucket capacitor CB is charged by connecting with the tank capacitor CT and the source capacitor CS is charged by connecting with the bucket capacitor CB and discharges from the output terminal to a load.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a DC / DC converter suitable for a power supply apparatus capable of rapid charging and a power supply method using the DC / DC converter.

  Conventionally, a DC / DC converter using an inductor has been used for the step-up / step-down of the DC voltage. In a DC / DC converter using an inductor, high voltage and large current output can be obtained with a wide range of input voltages. For example, a DC power supply system that outputs a stable voltage to a plurality of loads having different input voltages and power consumption has been proposed (see Patent Document 1). However, since an inductor is used, a space is required, which is not suitable for a small portable device. Further, since magnetic flux is generated in the inductor, radiation noise is generated, and noise countermeasures are required.

  In recent years, DC / DC converters using a charge pump that generates an output voltage by transition of electric charge between capacitors have been developed. For example, a charge pump using an electric double layer capacitor (EDLC) has been proposed as a booster circuit (see Patent Document 2). In addition, the charge pump has few external components such as a capacitor and a diode, and the radiation noise is small. Therefore, it is suitable for a low-power power source for mobile devices such as mobile phones and small devices such as light emitting diodes (LEDs) and liquid crystal displays (LCDs).

  In recent years, capacitors have been rapidly increased in capacity and manufactured and sold, and can be used as substitutes for batteries. However, when a capacitor is used, the output voltage drops as it is used, and a stable voltage cannot be supplied to the load. Therefore, it cannot cope with an automated guided vehicle (AVG) that requires a large current with a wide input voltage. In addition, since the capacitor is boosted by switching between the series connection and the parallel connection, the output voltage becomes about twice the reference voltage, and an arbitrary output voltage cannot be obtained.

JP 2011-78267 A Japanese Patent Laid-Open No. 2006-46993

  In view of the above problems, the present invention provides a DC / DC converter that can easily output a large current and can stably supply power at an arbitrary output voltage, and a power supply method using the DC / DC converter. For the purpose.

  In the first aspect of the present invention, (a) an input / output line connecting the input terminal and the output terminal, and the input / output line and the common line facing each other so as to form a two-terminal pair circuit are arranged. A tank capacitor, (b) a source capacitor disposed between the input / output line and the common line, and (c) a bucket having a smaller capacity than the tank capacitor and the source capacitor, disposed between the input / output line and the common line. DC / DC comprising a capacitor and (d) a control circuit that controls the connection relationship of the two-terminal pair circuit so that charging is performed by connecting the bucket capacitor to the tank capacitor and charging is performed by connecting the source capacitor to the bucket capacitor. The gist is that it is a DC converter. In the first mode, the load is discharged from the output port on the output terminal side of the two-terminal pair circuit.

  The second aspect of the present invention is such that an input / output line connecting the input terminal and the output terminal as described in the first aspect, and a common line when facing this input / output line so as to form a two-terminal pair circuit. A DC capacitor comprising a tank capacitor, a bucket capacitor and a source capacitor, a first switch connecting the intermediate node connected to the bucket capacitor and the common line, and a second switch connecting the input terminal and the intermediate node, respectively. The present invention relates to a power supply method for a DC converter. In the power supply method according to the second aspect, (a) the first switch is turned on and a reference voltage is applied between the input / output line and the common line to charge the tank capacitor, the bucket capacitor, and the source capacitor. And (b) discharging the load connected from the source capacitor to the output port on the output terminal side of the two-terminal pair circuit, and (c) outputting the output voltage from the output port during discharging. And (d) charging the bucket capacitor from the tank capacitor for a first set time by setting the first switch in a conductive state if the output voltage falls below the lower limit set value; and (e) the first set time. The method includes a step of charging the source capacitor from the bucket capacitor at a second set time after the first switch is turned off and the second switch is turned on. Furthermore, in the power supply method according to the second aspect, the capacity of the bucket capacitor is 1/10 to 1/100 that of the tank capacitor and the source capacitor, and the bucket capacitor to the bucket until the output voltage exceeds the upper limit set value. The charging of the capacitor and the charging of the source capacitor from the bucket capacitor are repeated.

  According to the present invention, it is possible to provide a DC / DC converter that can easily output a large current and can stably supply power at an arbitrary output voltage, and a power supply method using the DC / DC converter.

It is the schematic which shows an example of the DC / DC converter which concerns on the 1st Embodiment of this invention. FIG. 2 is a schematic diagram for explaining (a) charging, (b) discharge start, and (c) charge addition time of the DC / DC converter shown in FIG. 1. It is the schematic which shows an example of the DC / DC converter which concerns on the 2nd Embodiment of this invention. FIG. 4 is a schematic diagram showing a two-stage series connection of the DC / DC converter shown in FIG. 3. It is the schematic which shows an example of the connection of the control circuit used for the DC / DC converter which concerns on the 2nd Embodiment of this invention. It is the schematic explaining an example of the control circuit used for the DC / DC converter which concerns on the 2nd Embodiment of this invention. It is a plane schematic diagram showing an example of mounting of a DC / DC converter concerning a 2nd embodiment of the present invention. FIG. 8 is a schematic side view illustrating an example of implementation of the DC / DC converter illustrated in FIG. 7. It is a flowchart which shows an example of the electric power supply method which concerns on the 2nd Embodiment of this invention. It is the schematic of the DC / DC converter used for description of the electric power supply method which concerns on the 2nd Embodiment of this invention. It is a timing chart explaining the electric power supply method which concerns on the 2nd Embodiment of this invention. It is the schematic which shows an example of the operation waveform of the DC / DC converter by the power supply method which concerns on the 2nd Embodiment of this invention.

  Hereinafter, first and second embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and width of the layers, the ratio of the thicknesses of the layers, and the like are different from the actual ones. In addition, it goes without saying that portions with different dimensional relationships and ratios are also included in the drawings.

(First embodiment)
As shown in FIG. 1, the DC / DC converter according to the first embodiment of the present invention includes an input / output line 5 and a common line 6 facing the input / output line 5 so as to form a two-terminal pair circuit together with the input / output line 5. Are provided with tank capacitors (CT1, CT2), bucket capacitors CB, and source capacitors CS to form a pseudo “ladder circuit”. The input / output line 5 is connected between the input terminal 2 and the output terminal 4. The common line 6 is wired corresponding to the input / output line 5, and the terminal on the side corresponding to the input terminal 2 of the common line 6 and the input terminal 2 constitute an input port. In addition, an output port is constituted by the terminal corresponding to the output terminal 4 of the common line 6 and the output terminal 4. As shown in FIG. 1, the DC / DC converter according to the first embodiment is further charged by connecting the bucket capacitor CB to the tank capacitors (CT1, CT2) and connecting the source capacitor CS to the bucket capacitor CB. The control circuit 10a for controlling the connection relationship of the two-terminal pair circuit shown in FIG.

  As shown in FIG. 1, between the input / output line 5 and the common line 6, the first capacitor CT1 and the second capacitor CT2 of the tank capacitors (CT1, CT2) are connected to the first tank switch (Sa1, Sa2) and the second tank. H-type connection is made via the switch Sb. Further, as shown in FIG. 1, a source capacitor CS and a bucket capacitor CB are connected in parallel between the input / output line 5 and the common line 6. In the pseudo H-type connection circuit shown in FIG. 1, the second tank switch Sb is turned off (off) and the first tank switches (Sa1, Sa2) are turned on (on) at a specific timing. The first capacitor CT1 and the second capacitor CT2 are connected in parallel between the input / output line 5 and the common line 6. However, if the second tank switch Sb becomes conductive at another timing, the first and second capacitors CT1 and CT2 are connected in series between the input / output line 5 and the common line 6. In the input / output line 5, the bucket capacitor CB is connected to the input terminal 2 when the bucket switch Sc becomes conductive. In the input / output line 5, the source capacitor CS is connected to the bucket capacitor CB when the source switch Sd becomes conductive.

  Capacitors such as EDLC that can be used with a large current are used as the tank capacitors (CT1, CT2), the bucket capacitor CB, and the source capacitor CS. Large capacitors are used for the first and second capacitors CT1 and CT2. As the bucket capacitor CB, a capacitor having a small capacity of 1 / n (n is an integer of 2 or more) of the first and second capacitors CT1 and CT2. As the source capacitor CS, a capacitor having a capacity comparable to that of the first and second capacitors CT1, CT2 is used. Further, as the first and second tank switches Sa1, Sa2, Sb, bucket switch Sc, and source switch Sd, a semiconductor switching element is used as a more preferable aspect in addition to a mechanical switching element of an electromagnetic contactor. As semiconductor switching elements, insulated gate bipolar transistors (IGBT), field effect transistors (FET), electrostatic induction transistors (SIT), bipolar transistors (BJT), gate turn-off thyristors (GTO), electrostatic induction thyristors (SI thyristors) Etc. are suitable.

  The operation of the DC / DC converter according to the first embodiment will be described with reference to FIG. First, as shown in FIG. 2 (a), the first tank switches Sa1 and Ss2 are turned on, the second tank switch Sb is turned off, the bucket switch Sc is turned on, and the source switch Sd is turned on. To input voltage (reference voltage) Vin. As shown in FIG. 2B, the load is connected to the output terminal 4 of the source unit, all the switches are turned off, and discharge is started at the output voltage Vout. When the output voltage Vout falls below a predetermined set value, as shown in FIG. 2 (c), the second tank switch Sb is turned on, and the first and second capacitors CT1, CT2 are connected in series. The output of (CT1, CT2) is set to a voltage twice the input voltage Vin. In this state, the bucket switch CB is turned on to charge the bucket capacitor CB. Thereafter, the source switch Sd is turned on to restore the voltage supplied to the load by adding charge from the bucket capacitor CB to the source capacitor CS.

  In the DC / DC converter according to the first embodiment, the capacity of the bucket capacitor CB is as small as 1 / n of the tank capacitors (CT1, CT2) and the source capacitor CS, for example, 1/10 or less. A conventional booster circuit by switching between series and parallel corresponds to a case where n = 1 or no bucket capacitor. Therefore, in the conventional booster circuit, the output voltage becomes twice or an integer multiple of the reference voltage, and cannot be an arbitrary voltage. In the present invention, an arbitrary voltage can be set via the tank capacitors (CT1, CT2) and 1 / n of the source capacitor CS and the small-capacity bucket capacitor CB. When the value of n is small, the settable voltage becomes coarse. When the value of n is large, an output with less ripple can be obtained. However, when the value of n is large, the frequency of operation of the control circuit increases. Considering that the ripple of the output voltage is about 1% to 10%, the value of n is preferably 10 to 100.

  In the chopper type DC / DC converter using the inductor or the Dickson charge pump using the capacitor, the operating frequency is several kHz to several MHz. On the other hand, in the DC / DC converter according to the first embodiment, the operating frequency is at most several Hz. As described above, since the DC / DC converter according to the first embodiment has fewer switching times than the conventional DC / DC converter, the burden on the switch is small and noise is hardly generated at the same time. .

  In addition, since the conventional charge pump can only generate a voltage that is an integral multiple of the reference voltage, the output voltage cannot be controlled stably. In the present invention, the output voltage from the source capacitor CS is controlled by adding charge from the small-capacity bucket capacitor CB. As a result, the output can be set finely and stably at an arbitrary voltage. Moreover, by using EDLC, it can respond to a wide range of voltages and large currents, and can be applied to an automated guided vehicle (AGV).

(Second Embodiment)
As shown in FIG. 3, the DC / DC converter according to the second embodiment includes a tank capacitor CT, a bucket capacitor CB, a source capacitor CS, a first switch SW1, a second switch SW2, a first diode D1, and a second diode. A diode D2 is provided. The first switch SW1 is connected to the intermediate node 8 and the common line 6 connected to the bucket capacitor CB. The second switch SW2 is connected to the input terminal 2 and the intermediate node 8. In the input / output line 5, the first diode D1 has an anode connected to the input terminal 2 and a cathode connected to the bucket capacitor CB. The second diode D2 is connected in series to the first diode D1 in the input / output line 5, and has an anode connected to the bucket capacitor CB and a cathode connected to the source capacitor CS. The second embodiment differs from the first embodiment in that the first and second diodes D1 and D2 are used to simplify the number of switches. Other configurations are the same as those of the first embodiment, and thus redundant description is omitted.

  When the first switch SW1 is turned on and the second switch SW2 is turned off, the tank capacitor CT, the bucket capacitor CB, and the source capacitor CS are connected in parallel between the input / output line 5 and the common line 6. When an input voltage (reference voltage) Vin is applied to the input terminal 2 in this state, it is possible to charge the tank capacitor CT, the bucket capacitor CB, and the source capacitor CS by flowing an electric charge. When the first switch SW1 is turned off and the second switch SW2 is turned on, the tank capacitor CT and the bucket capacitor CB are connected in series. In this state, it is possible to charge the source capacitor CS by transferring the charge through the second diode D2. When the first and second switches SW1 are turned off, the source capacitor CS is disconnected from the tank capacitor CT and the bucket capacitor CB by the first and second diodes D1 and D2. In this state, when a load is connected to the output terminal 4, electric charge is discharged from the source capacitor CS, and power can be supplied to the load. Since the output voltage Vout is charged through the diode, it becomes lower than the input voltage Vin by the forward voltage of the diode even at full charge.

  The DC / DC converter according to the second embodiment corresponds to a one-stage Dickson charge pump if the bucket capacitor CB is a capacity when n = 1. In the case of a conventional Dixon charge pump, it is usually used in 10 stages or more, and there are few examples of using it in one stage. In addition, the Dixon charge pump is used for micro power, and there is no example used for high power. Further, in the Dixon charge pump, the output voltage becomes an integral multiple of the reference voltage, and cannot be set to an arbitrary voltage.

  Also in the second embodiment, the capacity of the bucket capacitor CB is 1 / n of the tank capacitor CT or the source capacitor CS, for example, 1/10 to 1/100, as in the first embodiment. For example, if n = 10, the output voltage Vout can be set to (Vin + Vin / 10) by connecting the tank capacitor CT and the bucket capacitor CB in series and charging the source capacitor CS. By selecting the capacity of the bucket capacitor CB, the output voltage Vout can be arbitrarily adjusted.

  Further, when the discharge from the source capacitor CS continues, the output voltage Vout gradually decreases. The output voltage Vout is monitored, and when the output voltage Vout drops below the set value, charging is performed by adding charge from the bucket capacitor CB. If the capacity of the bucket capacitor CB is 1/10 that of the tank capacitor CT or the source capacitor CS, charging can be performed by adding voltage (Vin / 10). Therefore, it is possible to eliminate the decrease in the output voltage Vout due to the discharge and supply power to the load with a constant output voltage Vout.

  If the DC / DC converter according to the second embodiment is connected in series, the output voltage can be increased. As shown in FIG. 4, two stages of DC / DC converters are connected in series. For example, if the input voltage Vin is 24V, the output voltage Vout is about 48V. If DC / DC converters are connected in m stages in series, the output voltage Vout can be increased to (mVin).

  A circuit for controlling the first and second switches SW1 and SW2 will be described. As shown in FIG. 5, as the first and second switches SW1 and SW2, IGBTs which are semiconductor switching elements having a small on-resistance (conduction loss) are used. The control circuit 10b acquires the output voltage Vout of the output terminal 4, and transmits the gate signals GS1 and GS2 to the gate electrodes of the first and second switches SW1 and SW2, respectively, to perform switching control.

  For example, as shown in FIG. 6, four IGBTs are used in parallel for each of the first and second switches SW1 and SW2. The IGBT of the first switch SW1 has a collector electrode connected to the intermediate node 8, an emitter electrode connected to the common line 6, and a gate electrode connected to the photocoupler 14 of the control circuit 10b. The IGBT of the second switch SW2 has a collector electrode connected to the tank capacitor CT, an emitter electrode connected to the intermediate node 8, and a gate electrode connected to the photocoupler 14 of the control circuit 10b. Note that a gate voltage based on the potential Vp of the intermediate node 8 needs to be applied to the second switch SW2.

  The control circuit 10b includes a microcontroller 12, a photocoupler 14, and a DC power source 16. The microcontroller 12 monitors the output voltage Vout from the source capacitor CS. The photocoupler 14 transmits the gate signals GS1 and GS2 sent from the microcontroller 12 to the gate electrodes of the first and second switches SW1 and SW2. The DC power supply 16 supplies power to the photocoupler 14.

  In the present invention, the basic operation is to repeatedly charge and discharge a plurality of capacitors. In addition, a large current must be switched. Therefore, mounting on a normal printed circuit board is not possible. Further, the first and second switches SW1 and SW2 require a parallel operation of a plurality of IGBTs, and noise due to induction to the gate circuit due to a sudden change in the collector current of the IGBT is likely to occur. Therefore, a circuit is configured using a copper plate.

  7 and 8 show a part of a mounting example of the DC / DC converter according to the second embodiment. As shown in FIGS. 7 and 8, the IGBTs of the first and second switches SW1 and SW2 are attached to the terminal board 20, respectively. The respective gate electrodes of the first switch SW1 are connected by the copper plate 31. Each gate electrode of the second switch SW2 is connected by a copper plate 32. Lead wires 28 from the photocoupler 14 are connected to the copper plates 31 and 32. The collector electrode of the first switch SW1 and the emitter electrode of the second switch SW2 are connected by a copper plate 24. The copper plate 24 is connected to the intermediate node 8 by a lead wire 25. The emitter electrode of the first switch SW1 is connected by the copper plate 26. The copper plate 26 is connected to the common line 6 by a lead wire 27. The collector electrode of the second switch SW2 is connected by the copper plate 22. The copper plate 22 is connected to the tank capacitor CT.

  In mounting the DC / DC converter according to the second embodiment, a thick copper plate with a thickness of 0.5 mm is used. As shown in FIG. 7, the copper plates 22, 24, 26, 31, and 32 have a large area. Therefore, a low-resistance current path can be secured and a large current can flow. In addition, since the current path is wide, generation of noise due to induction can be suppressed.

  Next, a power supply method according to the second embodiment will be described using the flowchart shown in FIG. The input voltage Vin is applied to the input terminal 2 when all the capacitors are charged. When the DC / DC converter is discharged, a load is connected to the output terminal 4. The microcontroller 12 acquires the source voltage Vs of the source capacitor CS corresponding to the output voltage Vout, and switches the first and second switches SW1 and SW2. The lower limit setting value for switching is Vset1, and the upper limit setting value is Vset2.

  In step S 10, the first switch SW 1 is turned on and the input voltage Vin is applied to the input / output line 5. The tank capacitor CT, bucket capacitor CB, and source capacitor CS are each charged.

  In step S11, the source voltage Vs is acquired, and it is determined whether the source voltage Vs exceeds the lower limit set value Vset1. If the source voltage Vs falls below the lower limit set value Vset1, the process returns to step S10 and charging is repeated.

  If the source voltage Vs exceeds the lower limit set value Vset1, the first switch SW1 is turned off in step S12. Discharge is started to the load connected to the output terminal 4 from the source capacitor CS.

  In step S13, the source voltage Vs of the source capacitor CS is acquired at the time of discharging to the load. It is determined whether the source voltage Vs exceeds the lower limit set value Vset1. If the source voltage Vs exceeds the lower limit set value Vset1, the process returns to step S12 to continue discharging.

  If the source voltage Vs is lower than the lower limit set value Vset1, in step S14, the first switch SW1 is turned on. The bucket capacitor CB is charged from the tank capacitor CT at the first set time T1. In addition, the discharge to the load continues after this.

  After the first set time T1, in step S15, the first switch SW1 is turned off and the second switch SW2 is turned on. The source capacitor CS is charged from the tank capacitor CT and the bucket capacitor CB at the second set time T2.

  In step S16, the source voltage Vs is acquired. It is determined whether the source voltage Vs exceeds the upper limit set value Vset2. If the source voltage Vs is lower than the upper limit set value Vset2, the process returns to step S14, and steps S14 and S15 are repeated until the source voltage Vs exceeds the upper limit set value Vset2.

  If the source voltage Vs exceeds the upper limit set value Vset2, the second switch SW2 is turned off in step S17. Thereafter, steps S13 to S16 are repeated while monitoring the source voltage Vs.

  FIG. 11 shows operation waveforms of the tank voltage Vt, the bucket voltage Vb, and the source voltage Vs shown in FIG. As shown in FIG. 11, the source voltage Vs continues to decrease during discharge. If the control circuit 10b determines that the source voltage Vs has fallen below the lower limit set value Vset1, the first switch SW1 is turned on, and the bucket capacitor CB is charged from the tank capacitor CT for the first set time T1. At this time, since the charge moves from the tank capacitor CT to the bucket capacitor CB, the tank voltage Vt decreases. Next, the second switch SW2 becomes conductive, and the source capacitor CS is charged from the tank capacitor CT and the bucket capacitor CB during the second set time T2. When the second switch SW2 becomes conductive, the bucket voltage Vb and the source voltage Vs increase instantaneously. During the second set time T2, the bucket voltage Vb and the source voltage Vs continue to decrease due to discharge to the load. At this time, since the movement of charges from the tank capacitor CT is small, the tank voltage Vt hardly changes. Thus, the above operation is continued until the source voltage Vs exceeds the upper limit set value Vset2.

  FIG. 12 shows operation waveforms of the tank voltage Vt, the bucket voltage Vb, and the source voltage Vs obtained by the power supply method according to the second embodiment. As shown in FIG. 12, every time the first switch SW1 is switched to the second switch SW2, the bucket voltage Vb and the source voltage Vs increase in a pulse shape. On the other hand, the tank voltage Vt decreases every time the first switch SW1 becomes conductive. It can be seen that the source voltage Vs is controlled within a certain range by the addition of the charge from the bucket capacitor CB.

  As described above, according to the second embodiment of the present invention, since charge is added from the small-capacity bucket capacitor CB, the output voltage Vout can be arbitrarily set, and the decrease in the output voltage Vout is suppressed. Power can be supplied to the load at a constant output voltage Vout. As a result, the output can be set finely and stably at an arbitrary voltage. Moreover, by using EDLC, it can respond to a wide range of voltages and large currents, and can be applied to an automated guided vehicle (AGV). Furthermore, since the number of times of switching of the switch is small as compared with the conventional method, the burden on the switch is small, and at the same time, it is difficult to generate noise.

(Other embodiments)
As described above, the present invention has been described according to the first or second embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

2 ... input terminal 4 ... output terminal 5 ... input / output line 6 ... common line 8 ... intermediate node 10a, 10b ... control circuit 12 ... microcontroller 14 ... photocoupler 16 ... DC power supply 20 ... terminal plates 22, 24, 26, 31 , 32 ... Copper plates 25, 27, 28 ... Lead wire CT ... Tank capacitor CB ... Bucket capacitor CS ... Source capacitor D1 ... First diode D2 ... Second diode Sa1, Sa2 ... First tank switch Sb ... Second tank switch Sc ... Bucket switch Sd ... source switch SW1 ... first switch SW2 ... second switch

Claims (6)

An input / output line connecting the input terminal and the output terminal, a tank capacitor disposed between the input / output line and a common line opposed to form a two-terminal pair circuit;
A source capacitor disposed between the input / output line and the common line;
A bucket capacitor disposed between the input / output line and the common line, having a smaller capacity than the tank capacitor and the source capacitor;
A control circuit that controls the connection relationship of the two-terminal pair circuit so that the bucket capacitor is charged by connecting to the tank capacitor and the source capacitor is charged by connecting to the bucket capacitor;
And a DC / DC converter that discharges to a load from an output port on the output terminal side of the two-terminal pair circuit.   2. The DC / DC converter according to claim 1, wherein a capacity of the bucket capacitor is 1/10 to 1/100 of the tank capacitor and the source capacitor. A first switch connected to the intermediate node connected to the bucket capacitor and the common line;
A second switch connected to the input terminal and the intermediate node;
A first diode having an anode connected to the input terminal and a cathode connected to the bucket capacitor in the input / output line;
3. The input / output line further comprising: a second diode connected in series to the first diode, having an anode connected to the bucket capacitor and a cathode connected to the source capacitor. DC / DC converter.   The wiring between the tank capacitor and the second switch, the wiring between the first and second switches and the intermediate node, and the wiring between the first switch and the common line are copper plates. The DC / DC converter according to claim 3. The tank capacitor includes a first capacitor and a second capacitor arranged to form a pseudo H-type connection circuit between the input / output line and the common line,
Between the input / output line and the common line, the first and second capacitors are connected in parallel at a specific timing, and the first and second capacitors are connected in series at other timings. A tank switch composed of a plurality of switches for changing the circuit connection;
A bucket switch for connecting the bucket capacitor to the input terminal in the input / output line when conducting;
The DC / DC converter according to claim 1, further comprising: a source switch that connects the source capacitor to the bucket capacitor in the input / output line when conducting. An input / output line connecting the input terminal and the output terminal, a tank capacitor, a bucket capacitor and a source capacitor disposed between the input / output line and a common line facing each other so as to form a two-terminal pair circuit, the bucket A power supply method for a DC / DC converter comprising a first switch connecting an intermediate node connected to a capacitor and the common line, and a second switch connecting the input terminal and the intermediate node,
Charging the tank capacitor, the bucket capacitor, and the source capacitor by bringing the first switch into a conductive state and applying a reference voltage between the input / output line and the common line;
Discharging the first switch from the source capacitor to a load connected to the output port on the output terminal side of the two-terminal pair circuit; and
Obtaining an output voltage from the output port during the discharge;
Charging the bucket capacitor from the tank capacitor in a first set time by turning on the first switch if the output voltage falls below a lower limit set value;
Charging the source capacitor from the bucket capacitor in a second set time by turning the first switch off and the second switch on after the first set time; and
The capacity of the bucket capacitor is 1/10 to 1/100 of the tank capacitor and the source capacitor, and the bucket capacitor is charged from the tank capacitor until the output voltage exceeds an upper limit setting value, and A method of supplying power, the method comprising repeatedly charging the source capacitor from the bucket capacitor.