JP2012231585A - Power inverter circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that an insulation converter by a current doubler rectification system can reduce a ripple current, but requires many magnetic components.SOLUTION: Coils W1, W2 constituting a transformer are magnetically coupled by a leg 12 of a magnetic core 10. Coils W3, W4 constituting a reactor are interlinked by legs 16, 18 of the magnetic core 10 respectively. The legs interlinking those coils W1-W4 and a leg 14 which does not interlink the coils are connected in parallel by connection parts 20, 22 of the magnetic core 10. Magnetic flux φ3 generated as a current flows to the coil W3 and magnetic flux φ4 generated as a current flow to the coil W4 are set to have the same polarity on a loop path including the leg 16, the connection part 20, the leg 18, and the connection part 22.

Description

  The present invention outputs a first coil connected to an output terminal of an AC voltage applying means, a second coil magnetically coupled to the first coil, a capacitor, and a current flowing through the second coil to the capacitor. A third coil and a fourth coil used in the above, a rectifying means for restricting a flow direction of direct current of the third coil and the fourth coil in one direction, and a magnetic core, and the third coil and the fourth coil. The present invention relates to a power conversion circuit in which polarities of voltages applied to the first coil when currents flowing through the coils gradually increase are opposite to each other.

  FIG. 10 shows an insulating converter based on a general current doubler rectification system (17 in FIG. 10 of Patent Document 1). In this converter, the output current is divided by a pair of reactors (coils W3 and W4), and each of them rectifies by flowing half of the output current. Since the pair of coils W3 and W4 are alternately excited by the transformer T, the ripples of the current flowing through them are overlapped by interleaving. For this reason, even if the respective inductances of the coils W3 and W4 are small, the ripple of the output current of the converter can be effectively reduced.

  Here, it is known that the size of the inductor is generally proportional to the energy product represented by the product of the square of the inductance and the energization current. Accordingly, the fact that the ripple is suppressed even if the inductances of the coils W3 and W4 are small means that the physiques of the coils W3 and W4 that satisfy the requirements for the ripple of the output current of the converter can be small. In fact, the current doubler rectification type isolated converter has a smaller total energy product of the smoothing coil to obtain the same ripple than the converter using other rectification methods such as a full-wave rectifier circuit in the output stage, It is known as a converter circuit effective for miniaturization.

Japanese Patent No. 3236825

  However, while the size of the smoothing inductor can be reduced, the configuration using three magnetic components, the transformer T and the smoothing coils (coils W3 and W4), has a disadvantage that the number of magnetic components is larger than that of other rectification methods. There is. Due to this drawback, there were the following three problems. First, considering the winding space, core dead space, etc., it is difficult to reduce the mounting body. The second problem is that the volume of the magnetic core cannot be reduced as much as expected from the energy product because the magnetic path is individually circulated for each magnetic component. Thirdly, there is a problem that production costs due to component mounting and the like are increased.

  The present invention has been made in the process of solving the above-mentioned problems, and the object thereof is a first coil connected to the output terminal of the AC voltage applying means, a second coil magnetically coupled to the first coil, A capacitor, a third coil and a fourth coil used for outputting the current flowing through the second coil to the capacitor, and a flow direction of direct current of the third coil and the fourth coil are restricted to one direction. A new power conversion circuit comprising a rectifier and a magnetic core, wherein the polarities of the voltages applied to the first coil when the currents flowing through the third coil and the fourth coil gradually increase are opposite to each other. It is to provide.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

  The invention according to claim 1 is the first coil connected to the output terminal of the AC voltage applying means, the second coil magnetically coupled to the first coil, the capacitor, and the current flowing through the second coil as the capacitor. A third coil and a fourth coil used for outputting to the first coil, a rectifying means for restricting a flow direction of a direct current of the third coil and the fourth coil in one direction, and a magnetic core, and the third coil. And in the power conversion circuit in which the polarity of the voltage applied to the first coil when the current flowing through each of the fourth coils gradually increases, the magnetic core is a portion that links the first coil, A portion that interlinks the second coil, a portion that interlinks the third coil, and a portion that interlinks the fourth coil are integrally formed.

  In the above invention, the magnetic cores for the third coil and the fourth coil functioning as the reactor and the magnetic core for magnetically coupling the first coil and the second coil functioning as the transformer are integrally formed. Reactor and transformer can be downsized.

  According to a second aspect of the present invention, in the first aspect of the present invention, the magnetic core has a portion constituting a loop path interlinking with both the third coil and the fourth coil, and in the loop path, The direction of the magnetic flux generated by the direct current component of the current flowing through the third coil and the direction of the magnetic flux generated by the direct current component of the current flowing through the fourth coil are set in the same direction.

  In the above-described invention, the direction in which the magnetic flux generated by the DC component of the current flowing through the third coil is linked to the fourth coil is changed to the linkage of the fourth coil generated by the DC component of the current flowing through the fourth coil. The direction of the magnetic flux can be matched. Further, the direction when the magnetic flux generated by the direct current component of the current flowing through the fourth coil is linked to the third coil is changed in the direction of the interlinkage magnetic flux of the third coil generated by the direct current component of the current flowing through the third coil. Can match the direction. For this reason, the situation where the direct-current magnetic flux generated by the current flowing through each of the third coil and the fourth coil is linked to the first coil and the second coil can be suitably suppressed. For this reason, it is suitably avoided that the magnetic saturation of the magnetic core for magnetically coupling the first coil and the second coil is promoted by the magnetic flux generated by the current flowing through each of the third coil and the fourth coil. can do. For this reason, it can avoid suitably that the size of the magnetic core for magnetically coupling the first coil and the second coil is increased.

  According to a third aspect of the present invention, in the invention of the second aspect, the magnetic core has a portion constituting a loop path interlinking with both the second coil and the third coil, and in the loop path, The direction of the alternating current component of the magnetic flux interlinking the third coil when the current flowing through the third coil increases matches the direction of the alternating current component of the magnetic flux interlinking the second coil. And

  Since the magnetic flux that links the third coil increases as the current flowing through the third coil increases, the magnetic flux that links the third coil may be larger than the magnetic flux that links the fourth coil. There is. In this case, the excess magnetic flux flows out to a path other than the loop path linked to both the third coil and the fourth coil. In this regard, in the above-described invention, by making up for the change in the magnetic flux interlinking the second coil by this outflow, it is possible to suitably suppress the need to increase the size of the magnetic core due to this outflow.

  The invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the number of turns of the third coil and the number of turns of the fourth coil are equal to each other.

  In the said invention, the symmetry of the magnetic flux produced | generated when an electric current flows into a 3rd coil, and the magnetic flux produced | generated when an electric current flows into a 4th coil is easily realizable.

  The invention according to claim 5 is the invention according to claim 2 or 3, wherein the magnetic core includes a first portion that links the first coil and the second coil, and a third portion that links the third coil. And a fourth part interlinking the fourth coil, and a part connecting the first part, the third part and the fourth part in parallel, and the first part, the third part and the second part. Further, in parallel with the four portions, a portion that does not link the coils is further provided.

  In the said invention, the part which does not link the said coil can be utilized as a path | route where the difference of the magnetic flux which links the 1st coil, the magnetic flux which links the 3rd coil, and the magnetic flux which links the 4th coil passes. .

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the portions that do not interlink the coil are provided on both sides of the first portion, the third portion, and the fourth portion. Features.

  In the above-described invention, the portion where the coils are not linked has the function of a magnetic shield, and the leakage of magnetic flux from the magnetic core to the surroundings can be suppressed.

  The invention according to claim 7 is the invention according to claim 3, wherein the number of turns of the second coil, the number of turns of the third coil, and the number of turns of the fourth coil are equal to each other.

  In the above invention, the difference between the magnetic flux interlinking the third coil and the magnetic flux interlinking the fourth coil is suitably absorbed by the path interlinking the second coil.

  According to an eighth aspect of the present invention, in the seventh aspect of the present invention, a portion of the magnetic core that constitutes a loop path that links both the first coil and the second coil is the second coil and the second coil. It is characterized in that it is formed by a part constituting a loop path interlinking with both of the three coils and a part constituting a loop path interlinking with both the second coil and the fourth coil.

  In the above invention, the structure of the magnetic core is simplified by sharing the loop path linked to both the first coil and the second coil with the loop path linked to both the second coil and the third coil. It becomes easy.

  According to a ninth aspect of the present invention, in the eighth aspect of the present invention, the magnetic core includes a portion constituting a loop path interlinking with both the second coil and the third coil, and the second coil and the second coil. A gap is provided in a portion other than the common portion of the pair of portions constituting the loop path interlinking with both of the four coils.

  In the said invention, since the magnetic saturation by the electric current which flows into a 3rd coil and a 4th coil can be suppressed suitably, a magnetic core can be reduced in size.

  The gap is preferably provided corresponding to each of the pair of portions.

  According to a tenth aspect of the present invention, in the eighth aspect of the present invention, the magnetic core includes a portion constituting a loop path interlinking with both the second coil and the third coil, and the second coil and the second coil. The magnetic permeability of at least a part of the material other than the common part of the pair of parts constituting the loop path interlinking with both of the four coils is smaller than the magnetic permeability of the material of the other part. Features.

  In the said invention, since the magnetic saturation by the electric current which flows into a 3rd coil and a 4th coil can be suppressed suitably, a magnetic core can be reduced in size.

  In addition, it is desirable that the portion having a small magnetic permeability is provided corresponding to each of the pair of portions.

  The invention according to claim 11 is the invention according to any one of claims 1 to 7, wherein the magnetic core is linked to both the first coil and the second coil, and the third coil and A gap is provided in a portion excluding a portion constituting a loop path not interlinked with any of the fourth coils.

  In the said invention, since the magnetic saturation by the electric current which flows into a 3rd coil and a 4th coil can be suppressed suitably, a magnetic core can be reduced in size.

  It is preferable that the magnetic core is divided into two parts by a portion constituting a loop path that does not link to any of the above, and the gap is provided in each of the divided parts.

  The invention according to claim 12 is the invention according to any one of claims 1 to 7, wherein the magnetic core is linked to both the first coil and the second coil, and the third coil and The magnetic permeability of at least some of the other materials is smaller than the magnetic permeability of the material constituting the loop path not interlinked with any of the fourth coils.

  In the said invention, since the magnetic saturation by the electric current which flows into a 3rd coil and a 4th coil can be suppressed suitably, a magnetic core can be reduced in size.

  In addition, the magnetic core is divided into two by a portion constituting a loop path that does not link to any of the above, and the portion having a low magnetic permeability is provided in each of the two divided portions. It is desirable to do.

  A thirteenth aspect of the invention is the invention according to any one of the first to twelfth aspects of the invention, wherein the first coil, the second coil, the third coil, the fourth coil, and the magnetic core are interposed between them. And an integrally formed bobbin.

  In the said invention, since the structure which links a magnetic core to a coil with a bobbin is realizable, the manufacture can be made easy.

The figure which shows the structure of the converter concerning 1st Embodiment. The time chart which shows the aspect of the chopper control concerning the embodiment. The perspective view which shows the magnetic component concerning 2nd Embodiment. The figure which shows the structure of the converter concerning 3rd Embodiment. The figure which shows the structure of the converter concerning 4th Embodiment. The figure which shows the structure of the converter concerning 5th Embodiment. The figure which shows the structure of the converter concerning 6th Embodiment. The circuit diagram which shows the circuit structure of the alternating voltage application means concerning the modification of each said embodiment. The figure for quantifying about the converter concerning this invention. The circuit diagram which shows the circuit structure of the conventional converter.

<First Embodiment>
Hereinafter, a first embodiment of a power conversion circuit according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a power conversion circuit according to this embodiment. 1 functions electrically equivalent to the circuit diagram of FIG.

  A smoothing capacitor C1 and an AC voltage application circuit AVC are connected in parallel to the illustrated DC voltage source (battery B). The AC voltage application circuit AVC is configured by connecting a series connection body of switching elements SW1 and SW2 and a series connection body of switching elements SW3 and SW4 in parallel. In the AC voltage application circuit AVC, when the switching element SW1 and the switching element SW4 are on and the switching element SW2 and the switching element SW3 are off, the switching element SW1 and the switching element SW4 are off, and the switching element SW2 and the switching element SW3 are on. The polarity of the output voltage is the same while the absolute value of the output voltage is the same.

  The output terminal of the AC voltage application circuit AVC is connected to the coil W1, and the coil W1 is magnetically coupled to the coil W2 by the cylindrical portion (foot 12) of the magnetic core 10. One end of the coil W2 is connected to the positive side of the capacitor C2 via a coil W3 constituting the reactor, and the other end of the coil W2 is connected to the capacitor via the coil W4 constituting the reactor. It is connected to the positive side of C2. The negative electrode side of the capacitor C2 is connected between the coil W2 and the coil W3 via the diode D1. For this reason, since the current from the negative electrode side of the capacitor C2 to the side between the coil W2 and the coil W3 is allowed and the reverse current is blocked, the current flowing through the coil W2 is output to the capacitor C2 via the coil W3. The current flow direction during the operation is restricted to one direction. The negative side of the capacitor C2 is connected between the coil W2 and the coil W4 via the diode D2. For this reason, the current from the negative electrode side of the capacitor C2 to the side between the coil W2 and the coil W4 is allowed and the reverse current is blocked, so that the current flowing through the coil W2 is output to the capacitor C2 via the coil W4. The current flow direction during the operation is restricted to one direction.

  The foot 12 is connected to the columnar portion (foot 14) via the connecting portions 20 and 22 of the magnetic core 10. Thereby, the magnetic core 10 includes the entire loop path that links the coils W1 and W2.

  The foot 12 is connected to the columnar portion (foot 16) that links the coil W3 via the connecting portions 20 and 22. The foot 16 is provided with a gap G provided for the purpose of avoiding magnetic saturation. The foot 12 is further connected to a columnar portion (foot 18) that links the coil W4 via the connecting portions 20 and 22. The foot 18 is provided with a gap G provided for the purpose of avoiding magnetic saturation.

  In the present embodiment, the condition “N3 = N4” is provided for the number of turns of the coils W1 to W4 (number of turns N1 to N4). This condition is one setting for facilitating securing the symmetry between the current Iw3 flowing through the coil W3 and the current Iw4 flowing through the coil W4. The number of turns is a value obtained by dividing the interlinkage magnetic flux of the coil by the magnetic flux in the coil.

  The legs 12, 14, 16, and 18 are all equal in length and arranged in parallel with each other, and the connecting portions 20 and 22 are portions for connecting them in parallel. In this way, the legs 12, 14, 16, 18 are connected by the connecting portions 20, 22, so that they are integrally formed. In particular, in this embodiment, the cross-sectional areas of the legs 16 and 18 are equal to each other, and the gaps of the respective gaps G are also set to be equal to each other. Further, as a ferromagnetic material that is a material of the magnetic core 10, ferrite or the like can be employed.

  Hereinafter, the operation of the power conversion circuit according to the present embodiment will be mainly qualitatively explained with reference to FIG. A more quantitative explanation about this is given in the remarks column at the end of this specification.

  Here, FIG. 2A shows the transition of the operation state of the switching element SW1, FIG. 2B shows the transition of the operation state of the switching element SW2, and FIG. 2C shows the transition of the switching element SW3. FIG. 2D shows the transition of the operation state of the switching element SW4. 2 (e) shows the transition of the voltage applied to both ends of the coil W1, FIG. 2 (f) shows the transition of the magnetic flux φ1 in the coil W1 (in the foot 12), and FIG. ) Shows the transition of the magnetic flux φ3 in the coil W3 (in the foot 16), FIG. 2 (h) shows the transition of the magnetic flux φ4 in the coil W4 (in the foot 18), and FIG. 14 shows the transition of the magnetic flux φ5 within the line 14. FIG. 2 (j) shows the transition of the current Iw3 flowing through the coil W3, and FIG. 2 (k) shows the transition of the current Iw4 flowing through the coil W4. Note that the signs of the magnetic fluxes φ1, φ3, φ4, φ5 and currents Iw3, Iw4 in FIG. 2 are defined in FIG.

"Mode 1"
In this state, the switching elements SW1 and SW4 are turned on and the switching elements SW2 and SW3 are turned off. Thereby, the voltage Vin of the battery B is applied to the coil W1, so that the magnetic flux φ1 induced by the coil W1 gradually increases, and a voltage is induced in the coil W2 shown in FIG. The voltage induced in the coil W2 causes a forward current to flow through the diode D2, while turning off the diode D1.

  Due to the voltage induced in the coil W2, the potential of the pair of terminals of the coil W3 that is not on the capacitor C2 side becomes higher. As a result, the magnetic flux φ3 induced by the coil W3 gradually increases, and the current Iw3 flowing through the coil W3 also increases gradually. Here, the current flowing through the coil W3 is substantially proportional to the magnetic flux φ3 induced by the coil W3. This is because the gap G is provided in the foot 16 (see the remarks column).

  On the other hand, since the diode D2 is in the on state, the capacitor C2 side of the potential of the pair of terminals of the coil W4 is higher. Thereby, magnetic flux φ4 induced by coil W4 gradually decreases according to the voltage of capacitor C2 (output voltage Vout of the power conversion circuit), and current Iw4 flowing through coil W4 also decreases gradually. Here, the current flowing through the coil W4 is substantially proportional to the magnetic flux φ4 induced by the coil W4. This is because the gap G is provided in the foot 18 (see the remarks column).

  At this time, the magnetic flux φ5 changes so as to satisfy “φ5 = φ1−φ3 + φ4”.

"Mode 2"
In this state, the switching elements SW2 and SW4 are turned on and the switching elements SW1 and SW3 are turned off. In this case, since the voltage across the coil W1 is zero, the magnetic flux φ1 induced by the coil W1 does not change. For this reason, the voltage across the coil W2 is also zero. On the other hand, a voltage having a polarity opposite to that in the mode 1 and having a magnitude of the output voltage Vout is applied to both ends of the coil W3. As a result, the magnetic flux φ3 induced by the coil W3 gradually decreases according to the output voltage Vout, and accordingly, the current Iw3 flowing through the coil W3 also gradually decreases. On the other hand, since a voltage having the same polarity and the same magnitude as that in the mode 1 is applied to both ends of the coil W4, the magnetic flux φ4 induced by the coil W4 gradually decreases, and the current Iw4 flowing through the coil W4. Gradually decreases. The current flowing through the coils W3 and W4 flows through at least one of the diodes D1 and D2. In mode 2, the voltage of the coil W2 is zero. In mode 2, both the diodes D1 and D2 are on. It becomes.

  At this time, the magnetic flux φ5 does not change. This is due to the setting “N3 = N4”.

"Mode 3"
In this state, the switching elements SW1 and SW4 are turned off and the switching elements SW2 and SW3 are turned on. In this embodiment, the mode 3 period is set to be the same as the mode 1 period. This is a setting for preventing the magnetic flux φ1 induced by the coil W1 from becoming a magnitude that causes the magnetic core 10 to be magnetically saturated, and the current Iw3 flowing through the coil W3 in cooperation with the above-described condition “N3 = N4”. And the current Iw4 flowing through the coil W4 is one setting for ensuring symmetry.

  In this case, the coil W1 is applied with a voltage having a polarity opposite to that of the mode 1 and having a voltage Vin of the battery B, so that the magnetic flux φ1 induced by the coil W1 is gradually reduced. A voltage is induced in the coil W2 shown in FIG. The voltage induced in the coil W2 causes a forward current to flow through the diode D1, while turning off the diode D2.

  Due to the voltage induced in the coil W2, the potential of the pair of terminals of the coil W4 that is not on the capacitor C2 side becomes higher. Thereby, magnetic flux φ4 induced by coil W4 gradually increases according to output voltage Vout, and current Iw4 flowing through coil W4 also increases gradually.

  On the other hand, since the diode D1 is in the ON state, the capacitor C2 side is higher in the potential of the pair of terminals of the coil W3. As a result, the magnetic flux φ3 induced by the coil W3 gradually decreases according to the output voltage Vout, and the current Iw3 flowing through the coil W3 also decreases gradually.

  At this time, the magnetic flux φ5 changes so as to satisfy “φ5 = φ1−φ3 + φ4”.

"Mode 4"
As in mode 2, the switching elements SW2 and SW4 are on and the switching elements SW1 and SW3 are off. In this case, since the voltage across the coil W1 is zero, the magnetic flux φ1 induced by the coil W1 does not change. For this reason, the voltage across the coil W2 is also zero.

  On the other hand, since a voltage having the same polarity and the same magnitude as that in the mode 3 is applied to both ends of the coil W3, the magnetic flux φ3 induced by the coil W3 gradually decreases, and the current Iw3 flowing through the coil W3 also gradually decreases. To do. On the other hand, a voltage having a polarity opposite to that in the mode 3 and having a magnitude of the output voltage Vout is applied to both ends of the coil W4. As a result, the magnetic flux φ4 induced by the coil W4 gradually decreases, and accordingly, the current Iw4 flowing through the coil W4 also gradually decreases. The current flowing through the coils W3 and W4 flows through at least one of the diodes D1 and D2. In mode 4, since the voltage of the coil W2 is zero, in mode 4, both the diodes D1 and D2 are on. Will be.

  At this time, the magnetic flux φ5 does not change. This is due to the setting “N3 = N4”.

  Next, the effect of this embodiment will be described.

  In this embodiment, the dead space between the magnetic components can be reduced by integrally forming the magnetic core of the transformer constituted by the coils W1 and W2 and the magnetic cores of the coils W3 and W4 functioning as reactors. The power conversion circuit can be reduced in size.

  Here, when the transformer and the core of the reactor are configured integrally, the average magnetic flux of the reactor (DC component of the magnetic fluxes φ3 and φ4) is configured not to pass through the transformer core (foot 12, 14). The enlargement of the part is avoided. This is because the DC component of the magnetic flux φ3 induced by the coil W3 (the average value of the magnetic flux φ3 shown in FIG. 2G) and the DC component of the magnetic flux φ4 induced by the coil W4 (the magnetic flux φ4 shown in FIG. 2H). Is set to be in the same direction on the loop path formed by the foot 16, the connecting portion 20, the foot 18, and the connecting portion 22. That is, in this case, out of the DC components of the magnetic fluxes φ3 and φ4, the amount of inflow into the legs 12 and 14 is only the difference between the DC component of the magnetic flux φ3 and the DC component of the magnetic flux φ4. In particular, in the present embodiment, these DC components are equal to each other by making the magnetic flux φ3 and the magnetic flux φ4 have symmetry. For this reason, since direct current components of the magnetic fluxes φ3 and φ4 do not flow into the feet 12 and 14, it is not necessary to design the feet 12 and 14 in consideration of the magnetic flux of the direct current component. In other words, it is not necessary to increase the size of the magnetic cores (foot 12, 14) of the transformer part by forming them integrally.

Furthermore, in the present embodiment, in the loop path that includes the foot 12, the connecting portion 20, the foot 16, and the connecting portion 22 and penetrates the coils W1 and W3, the AC component of the magnetic flux φ3 in the reactor portion (the average value is calculated from the magnetic flux φ3). And the direction of the magnetic flux φ1 induced by the coil W1. Further, in the loop path that includes the foot 12, the connecting portion 20, the foot 18, and the connecting portion 22 and penetrates the coils W1 and W4, the AC component of the magnetic flux φ4 in the reactor portion (subtracting the average value from the magnetic flux φ4) The direction was matched with the direction of the magnetic flux φ1 induced by the coil W1. That is, as shown in FIG. 2, when the magnetic flux φ1 increases, the magnetic flux φ3 in the same direction as the magnetic flux φ1 increases in the loop path that passes through the coils W1 and W3 (interlinks with the coils W1 and W3). In addition, the magnetic flux φ4 in the direction opposite to the magnetic flux φ1 is decreased in the loop path interlinking with the coils W1 and W4. Further, when the magnetic flux φ1 decreases, the magnetic flux φ3 in the same direction as the magnetic flux φ1 decreases in the loop path linked to the coils W1 and W4, and is opposite to the magnetic flux φ1 in the loop path linked to the coils W1 and W3. The magnetic flux φ4 in the direction was increased. Thereby, since the magnetic flux (flux φ5) that overflows and flows out of these loop paths can be reduced suitably, the foot 14 can be reduced in size.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 3 shows a magnetic component according to this embodiment. In FIG. 3, the same reference numerals are given for the sake of convenience to those corresponding to the members shown in FIG. 1.

In the present embodiment, the coils W1, W2, W3, and W4 are wound around the bobbins 30 covering the legs 12, 16, and 18 of the magnetic core 10, and then inserted into the legs 12, 14, 16, and 18 of the magnetic core 10. . Here, the bobbin 30 is formed integrally with a portion around which the coils W1 to W4 are wound. With such a configuration, it is possible to easily manufacture the magnetic component. It is desirable that bobbin 30 has a function of insulating coils W1-W4 and magnetic core 10 by being made of an insulator such as resin or plastic. Further, in order to reduce leakage magnetic flux from the magnetic core 10, it is desirable that the bobbin 30 be made of a material having a lower magnetic permeability than the magnetic core 10.
<Third Embodiment>
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 4 shows a power conversion circuit according to this embodiment. In FIG. 4, the same reference numerals are assigned for convenience to the members corresponding to those shown in FIG.

In the present embodiment, a pair of legs 14a and 14b sandwiching both sides of the legs 12, 16, and 18 are provided instead of the legs 14 shown in FIG. Thereby, since the legs 14a and 14b that do not link the coils have a function of a magnetic shield, the magnetic flux leaking from the magnetic core 10 to the surroundings can be reduced. For this reason, since the magnetic shield provided around the magnetic core 10 can be deleted or downsized, the power conversion circuit can be further downsized.
<Fourth Embodiment>
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 5 shows a power conversion circuit according to the present embodiment. In FIG. 5, the same reference numerals are given for convenience to those corresponding to the members shown in FIG. 1.

  In the above embodiment, the gap G is formed in each of the foot 16 that links the coil W3 and the foot 18 that links the coil W4. However, in this embodiment, these feet 16 and 18 are made of low dust or the like. It is made of a magnetic permeability material. Specifically, the portions other than the legs 16 and 18 of the magnetic core 10 may be made of ferrite and the legs 16 and 18 may be made of a dust core such as carbonyl iron dust having a lower magnetic permeability.

Thereby, compared with the case where the gap G is provided, since the leakage magnetic flux can be reduced, the eddy current induced by the leakage magnetic flux can be reduced. Further, when the bobbin 30 is not provided as exemplified in the present embodiment, the provision of the gap G can be an obstacle when winding the coils W3 and W4, but this can be avoided.
<Fifth Embodiment>
Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

  FIG. 6 shows a power conversion circuit according to this embodiment. In FIG. 6, the same reference numerals are given for convenience to those corresponding to the members shown in FIG. 1.

In the present embodiment, the number of turns N2 of the coil W2, the number of turns N3 of the coil W3, and the number of turns N4 of the coil W4 are the same. In this case, since the magnetic flux φ5 can be zero (see the remarks column), the foot 14 is deleted in the present embodiment. Thereby, the structure of the magnetic core 10 can be simplified.
<Sixth Embodiment>
Hereinafter, the sixth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 7 shows a power conversion circuit according to this embodiment. In FIG. 7, components corresponding to those shown in FIG. 1 are given the same reference numerals for convenience.

In this embodiment, the forward directions of the diodes D1 and D2 are reversed. Even in this case, the current flow direction of the coils W3 and W4 can be restricted to one direction. At this time, since the directions of the magnetic fluxes φ3 and φ4 are reversed from those shown in FIG. 1, the directions of the currents Iw3 and Iw4 are reversed, and the polarity of the voltage of the capacitor C2 is also reversed. In addition, when the current of the coil W3 gradually increases, a setting in which the current of the coil W4 gradually decreases and when the current of the coil W4 increases gradually can be realized. The ripple of the input current can be suitably suppressed.
<Other embodiments>
Each of the above embodiments may be modified as follows.

About AC voltage application means
Not only what was shown in previous FIG. 1, but what may be illustrated, for example in FIG. 8 (a)-FIG.8 (c) may be sufficient. Here, FIG. 8A shows a configuration in which a series connection body of capacitors C3 and C4 is used in place of the series connection body of the switching elements SW3 and SW4 in the configuration shown in FIG.

  FIG. 8B shows the configuration shown in FIG. 1 in which the serial connection body of the switching elements SW3 and SW4 is deleted, and the serial connection body of the capacitor C5 and the coil W1 is connected in parallel to the switching element SW2. is there.

  FIG. 8C shows the connection of the switching elements SW1 and SW2 with the midpoint tap of the coil W1 connected via the battery B.

  Note that the absolute values of the positive voltage and the negative voltage applied by the AC voltage applying means are not necessarily the same. In this case, in the description of each of the above embodiments, the description on the assumption that they are the same is generally not applicable, but when the difference between the absolute values of the positive voltage and the negative voltage is small, it is approximately It is possible to apply.

“Setting of coils W3 and W4”
The turns N3 and N4 of the coils W3 and W4 need not be equal. In particular, if the absolute values of the positive voltage and the negative voltage applied by the AC voltage applying means are not equal, the symmetry of the behavior of the magnetic fluxes φ3 and φ4 is lost even if the numbers of turns N3 and N4 are equal.

“Foot 14 not linked to coil”
The number of legs is not limited to 1 or 2, and may be 3 or more. Further, instead of the third embodiment (FIG. 4), the foot 14 may be provided so as to block all the feet 12, 16, and 18 from the outside in cooperation with the connecting portions 20 and 22. .

  In the fifth embodiment (FIG. 6), the foot 14 may be provided while reducing its cross-sectional area. Thereby, even if it is a case where it deviates from the theoretical calculation in the following "remarks" column, a leakage flux can be suppressed suitably.

"others"
The rectifying means is not limited to the diodes D1 and D2, but may be a thyristor or the like.

-In a loop path including the foot 16, the connecting portion 20, the foot 18, and the connecting portion 22, even if the directions of the magnetic flux φ3 and the magnetic flux φ4 are not the same, the feet 12 to 18 and the connecting portions 20, 22 are provided. By integrally configuring the magnetic cores of the transformer and the reactor, it is possible to reduce the size of the magnetic component, although not as much as in the first embodiment.
<Remarks>
Here, in the configuration shown in FIG. 1, the temporal change of the magnetic fluxes φ1, φ3, φ4, and φ5 in each mode is quantified. In the following, a general discussion is given for the case where the number of turns N1 to N5 takes an arbitrary value.

"Mode 1"
dφ1 / dt = Vin / N1 (c1)
dφ3 / dt = (N2 / Vin / N1-Vout) / N3 (c2)
dφ4 / dt = −Vout / N4 (c3)
dφ5 / dt
= (1-N2 / N3) Vin / N1 + (1 / N3-1 / N4) Vout (c4)
In the above equation (c4), “φ5 = φ1−φ3 + φ4” obtained by time differentiation is used.

"Mode 2"
dφ1 / dt = 0 (c5)
dφ3 / dt = −Vout / N3 (c6)
dφ4 / dt = −Vout / N4 (c7)
dφ5 / dt = (1 / N3-1 / N4) Vout (c8)
"Mode 3"
dφ1 / dt = −Vin / N1 (c9)
dφ3 / dt = −Vout / N3 (c10)
dφ4 / dt = (N2 · Vin / N1−Vout) / N4 (c11)
dφ5 / dt
=-(1-N2 / N4) Vin / N1 + (1 / N3-1 / N4) Vout (c12)
"Mode 4"
dφ1 / dt = 0 (c13)
dφ3 / dt = −Vout / N3 (c14)
dφ4 / dt = −Vout / N4 (c15)
dφ5 / dt = (1 / N3-1 / N4) Vout (c16)
“Time setting for mode 1 and mode 3”
According to the description of the above (c1), (c5), (c9), and (c13), when the times of mode 1 to mode 4 are fixed and these are periodically repeated, the absolute value of the magnetic flux φ1 is caused by DC bias. This means that the time of mode 1 and mode 3 must be equal to each other so that the value does not become too large. However, the method of eliminating the magnetic saturation due to the magnetic flux φ1 is not limited to this, and at least one of the modes 1 and 3 is changed in each cycle to change the time per mode in the modes 1 and 3. The sum may be equal to each other.

  When the positive voltage and the negative voltage by the AC voltage application means are not equal, the same “Vin” is used in the above formulas (c1) to (c4) and the above formulas (c9) to (c12). It is not possible. For this reason, even if each time of mode 1 to mode 4 is fixed and these are repeated periodically, it is required to make the time of mode 1 and mode 3 different in order to avoid magnetic saturation. Is done.

“Symmetry of the behavior of φ3 and φ4”
Assuming that the number of turns N3 and the number of turns N4 are equal, from the relationship of the above formulas (c2), (c3), (c6), (c7), (c10), (c11), (c14), (c15) The gradually increasing speed of the magnetic flux φ3 in mode 1 and the gradually increasing speed of the magnetic flux φ4 in mode 3 are equal to each other, and the gradually decreasing speeds of the magnetic fluxes φ3 and φ4 are also equal to each other. In particular, when the times of mode 1 and mode 3 are equal, the increase amount and the decrease amount in one cycle of φ3 and φ4 are equal to each other.

“About the behavior of φ1 and φ5”
From the relationship of φ1-φ5 = φ3-φ4, the average value of “φ1-φ5” and the average value of “φ3-φ4” are equal to each other. Here, assuming that “N3 = N4” and “mode 1 time = mode 3 time”, the average value of “φ3−φ4” is zero from the above discussion. For this reason, the average value of “φ1-φ5” is also zero. In addition, if “mode 1 time = mode 3 time”, the average value of φ1 is zero, so the average value of φ5 is also zero.

“Relationship between φ3 and φ4 and Iw3 and Iw4”
FIG. 9 shows a general configuration of the magnetic core 10 shown in FIG. 1 (the presence or absence of a gap is not specified). Here, if the magnetic resistance Rb in the region Lμb is dominant as the magnetic resistance in the loop path lb indicated by the one-dot chain line, “φ4 = N4 · Iw4 / Rb” is established by the magnetic circuit equation. This is because, when the approximation of “B = μH” is established according to the Maxwell equation, in the loop path lb, H is particularly large at a portion where the permeability μ is particularly small (a portion where the magnetic resistance is particularly large). This is equivalent to the explanation that the line integral of the field H along the loop path lb can be approximated by this part of the integral.

  Further, regarding the loop path lc indicated by a broken line, if the magnetic resistances Ra and Rb of the regions Lμa and Lμb are dominant, “Ra · φ3 + Rb · φ4 = N4 · I4 + N3 · Iw3”. Therefore, it can be approximated as “Ra · φ3 = N3 · Iw3”.

  From the above discussion, the changes in the currents Iw3 and Iw4 can be approximated by changes in the magnetic fluxes φ3 and φ4 by making the magnetic resistances in the regions Lμa and Lμb dominant for the magnetic resistance in the magnetic core 10.

  Note that, if a gap is provided only in a portion other than the region Lμa and the region Lμb so that the magnetic resistance of the portion is increased to a level that cannot be ignored, the energy transmission efficiency by the transformer T is reduced. However, this does not mean that no gap can be provided in the portion related to the transformer T (portions other than the regions Lμa and Lμb in FIG. 9) of the magnetic core 10. For example, it is possible to provide a magnetic field detection element by providing a gap in this portion.

  10: Magnetic core, W1 to W4: Coil, AVC: AC voltage application circuit.

Claims (13)

A first coil connected to the output terminal of the AC voltage applying means, a second coil magnetically coupled to the first coil, a capacitor, and a first coil used to output a current flowing through the second coil to the capacitor. Three coils and a fourth coil, rectifying means for restricting the flow direction of direct current of the third coil and the fourth coil in one direction, and a magnetic core, each of the third coil and the fourth coil In the power conversion circuit in which the polarities of the voltages applied to the first coil when the flowing current gradually increases are opposite to each other,
The magnetic core is integrally formed with a portion linking the first coil, a portion linking the second coil, a portion linking the third coil, and a portion linking the fourth coil. A power conversion circuit characterized by being a thing. The magnetic core has a portion constituting a loop path interlinking with both the third coil and the fourth coil;
In the loop path, the direction of the magnetic flux generated by the direct current component of the current flowing through the third coil and the direction of the magnetic flux generated by the direct current component of the current flowing through the fourth coil are set in the same direction. The power conversion circuit according to claim 1. The magnetic core has a portion constituting a loop path interlinking with both the second coil and the third coil;
In the loop path, the direction of the alternating current component of the magnetic flux interlinking the third coil when the current flowing through the third coil increases matches the direction of the alternating current component of the magnetic flux interlinking the second coil. The power conversion circuit according to claim 2, wherein the power conversion circuit is configured as described above.   4. The power conversion circuit according to claim 1, wherein the number of turns of the third coil is equal to the number of turns of the fourth coil.   The magnetic core includes a first part interlinking the first coil and the second coil, a third part interlinking the third coil, a fourth part interlinking the fourth coil, and the first part. And a portion that connects the third portion and the fourth portion in parallel, and further includes a portion that is not linked to the coil in parallel with the first portion, the third portion, and the fourth portion. The power conversion circuit according to claim 2 or 3.   The power conversion circuit according to claim 5, wherein the portions not interlinked with the coil are provided on both sides of the first portion, the third portion, and the fourth portion.   4. The power conversion circuit according to claim 3, wherein the number of turns of the second coil, the number of turns of the third coil, and the number of turns of the fourth coil are equal to each other.   The portion of the magnetic core that constitutes a loop path that interlinks with both the first coil and the second coil is a portion that constitutes a loop path that interlinks with both the second coil and the third coil; and The power conversion circuit according to claim 7, wherein the power conversion circuit is formed by a portion constituting a loop path interlinking with both the second coil and the fourth coil.   The magnetic core includes a pair of portions constituting a loop path interlinking with both the second coil and the third coil, and a portion constituting a loop path interlinking with both the second coil and the fourth coil. The power conversion circuit according to claim 8, further comprising a gap in a portion other than the common portion.   The magnetic core includes a pair of portions constituting a loop path interlinking with both the second coil and the third coil, and a portion constituting a loop path interlinking with both the second coil and the fourth coil. 9. The power conversion circuit according to claim 8, wherein the magnetic permeability of at least a part of the material other than the common part is smaller than the magnetic permeability of the material of the other part.   The magnetic core has a gap in a portion excluding a portion constituting a loop path that is linked to both the first coil and the second coil and that is not linked to any of the third coil and the fourth coil. The power conversion circuit according to any one of claims 1 to 7, further comprising:   The magnetic core is connected to both the first coil and the second coil, and the magnetic permeability of the material constituting the loop path that does not link to either the third coil or the fourth coil. 8. The power conversion circuit according to claim 1, wherein the magnetic permeability of at least some of the other materials is smaller.   13. The bobbin formed integrally between the first coil, the second coil, the third coil, the fourth coil, and the magnetic core is provided. 13. The power conversion circuit according to the item.

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