Power converters and transformers

Abstract

An object of the present invention is to reduce the size of a transformer used in a power conversion device or to suppress losses generated in the power conversion device. 【Solution means】The intermediate power converter 10M includes a primary winding L to which a primary switching circuit 12P is connected a and a secondary winding L coupled thereto b and an intermediate switching bridge BM to which the secondary winding L is connected b and a capacitor unit CM connected to the intermediate switching bridge BM b and a tertiary winding L connected in parallel to the secondary winding L and to which a secondary switching circuit 12S is connected d and a quaternary winding L coupled thereto c . The intermediate switching bridge BM switches the voltage output from the capacitor unit CM and applies it to the secondary winding L b and the tertiary winding L c . The pair of the primary winding L a and the secondary winding L b and the pair of the tertiary winding L c and the quaternary winding L d are not coupled or have a structure that suppresses mutual coupling.

Description

[Technical Field]

[0001] This invention relates to power converters and transformers, and more particularly to improvements of these technologies. [Background technology]

[0002] Power converters that combine multiple switching circuits using a transformer are widely used. One of the multiple windings constituting the transformer is connected to a switching circuit, for example, an electrical circuit installed in an electric vehicle. The other windings are connected to switching circuits, for example, a commercial power supply. Because the electrical circuit installed in the electric vehicle and the commercial power supply are electrically isolated by the transformer, handling the commercial power supply becomes easier, even when a high-output voltage battery is installed in the electric vehicle.

[0003] Such power conversion devices include those described in Patent Documents 1 and 2, and Non-Patent Documents 1 and 2, in which the power transmitted from one switching circuit to the other is determined by the difference between the switching phase of one of the two switching circuits and the switching phase of the other. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2013 / 037696 [Patent Document 2] Japanese Patent Publication No. 2018-148623 [Non-patent literature]

[0005] [Non-Patent Document 1] Ouyang, Ziwei, Zhe Zhang, Michael AE Andersen, and Ole C. Thomsen. "Four quadrants integrated transformers for dual-input isolated DC-DC converters." IEEE transactions on power electronics 27, no. 6 (2012): 2697-2702. [Non-Patent Document 2] [1]: Zhao, C., Round, SD and Kolar, JW, 2008. An isolated three-port bidirectional DC-DC converter with decoupled power flow management. IEEE transactions on power electronics, 23(5), pp.2443-2453. [Overview of the project] [Problems that the invention aims to solve]

[0006] In conventional power conversion devices, a large winding ratio for the transformer sometimes resulted in a large transformer. Furthermore, for example, if a DC / DC converter is configured by two switching circuits coupled by a transformer, and one of the switching circuits operates as a boost converter, the losses generated in the switching circuit can become large depending on the relationship between the boost ratio of the boost converter and the winding ratio of the transformer.

[0007] The object of the present invention is to make transformers used in power conversion devices smaller, or to suppress losses that occur in power conversion devices. [Means for solving the problem]

[0008] The present invention comprises a secondary winding coupled to a primary winding to which a primary switching circuit is connected, a switching bridge to which the secondary winding is connected, a capacitance unit connected to the switching bridge, and a tertiary winding connected in parallel to the secondary winding and coupled to a quaternary winding to which a secondary switching circuit is connected, wherein the switching bridge switches the voltage output by the capacitance unit and applies it to the secondary winding and the tertiary winding, and has a structure that prevents coupling between the pair of the primary winding and the secondary winding and the pair of the tertiary winding and the quaternary winding, or suppresses coupling between them.

[0009] In one embodiment, the switching bridge comprises two switching elements connected in series, the capacitance unit comprises two divided capacitors connected in series and in parallel with the switching bridge, one end of the secondary winding is connected to the connection point of the two switching elements of the switching bridge, and the other end of the secondary winding is connected to the connection point of the two divided capacitors of the capacitance unit.

[0010] In one embodiment, the switching bridge comprises two switching elements connected in series, the capacitance section comprises two divided capacitors connected in series and in parallel to the switching bridge, the secondary winding comprises a first separated secondary winding connected between one end of the switching bridge and one end of the capacitance section, and a second separated secondary winding connected between the other end of the switching bridge and the other end of the capacitance section, the tertiary winding comprises a first separated tertiary winding connected in parallel to the first separated secondary winding and a second separated tertiary winding connected in parallel to the second separated secondary winding, and the connection point of the two switching elements of the switching bridge is connected to the connection point of the two divided capacitors of the capacitance section.

[0011] In one embodiment, the power transmitted between the primary switching circuit and the secondary switching circuit is adjusted by adjusting the difference between the phase of the voltage applied by the primary switching circuit to the primary winding and the phase of the voltage applied by the switching bridge to the secondary winding, and the difference between the phase of the voltage applied by the switching bridge to the tertiary winding and the phase of the voltage applied by the secondary switching circuit to the quaternary winding.

[0012] In one embodiment, the primary winding to the fourth winding constitutes a transformer, and the transformer comprises, in addition to the primary winding to the fourth winding, a first columnar core, a second columnar core, a third columnar core and a fourth columnar core, a first common core to which one end of each of the first columnar cores to the fourth columnar core is connected, and a first common core to which the other end of each of the first columnar cores to the fourth columnar core is connected, wherein the primary winding wraps around the first columnar core and the fourth columnar core bundled together, the secondary winding wraps around the second columnar core and the third columnar core bundled together, the tertiary winding wraps around the first columnar core and the second columnar core bundled together, and the fourth winding wraps around the third columnar core and the fourth columnar core bundled together, and magnetic flux passing through the first columnar core and the fourth columnar core in the same direction in the longitudinal direction. The primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and the direction of magnetic flux passage is reversed between the first and fourth columnar cores and between the second and third columnar cores; or the primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and second columnar cores in the same longitudinal direction, and magnetic flux passes through the third and fourth columnar cores in the same longitudinal direction, and the direction of magnetic flux passage is reversed between the first and second columnar cores and between the third and fourth columnar cores.

[0013] In one embodiment, the primary winding to the fourth winding constitutes a transformer, and the transformer, in addition to the primary winding to the fourth winding, comprises a first columnar core, a second columnar core, a third columnar core and a fourth columnar core, a first common core to which one end of each of the first columnar cores to the fourth columnar core is connected, and a second common core to which the other end of each of the first columnar cores to the fourth columnar core is connected, and the primary winding is the The first columnar core and the fourth columnar core are bundled together and circled, the first separated secondary winding and the second separated secondary winding bundle the second columnar core and the third columnar core and circled, the first separated tertiary winding and the second separated tertiary winding bundle the first columnar core and the second columnar core and circled, the quaternary winding bundles the third columnar core and the fourth columnar core and circled, and the first columnar core and the fourth columnar core The primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and fourth columnar cores in the same direction in the longitudinal direction, and magnetic flux passes through the second and third columnar cores in the same direction in the longitudinal direction, and the direction of magnetic flux passage is reversed between the first and fourth columnar cores and between the second and third columnar cores, or the primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and second columnar cores in the same direction in the longitudinal direction, and magnetic flux passes through the third and fourth columnar cores in the same direction in the longitudinal direction, and the direction of magnetic flux passage is reversed between the first and second columnar cores and between the third and fourth columnar cores.

[0014] In one embodiment, the quaternary winding comprises a first separated quaternary winding and a second separated quaternary winding, the first separated quaternary winding and the second separated quaternary winding bundle together and circumferentially surround the third columnar core and the fourth columnar core.

[0015] Furthermore, the present invention comprises a first columnar core, a second columnar core, a third columnar core, and a fourth columnar core; a first common core to which one end of each of the first columnar cores and the fourth columnar core is connected; a second common core to which the other end of each of the first columnar cores and the fourth columnar core is connected; a primary winding that bundles and circles the first columnar core and the fourth columnar core; a secondary winding that bundles and circles the second columnar core and the third columnar core; a tertiary winding that bundles and circles the first columnar core and the second columnar core; and a quaternary winding that bundles and circles the third columnar core and the fourth columnar core, wherein magnetic flux in the same direction in the longitudinal direction passes through the first columnar core and the fourth columnar core, and The present invention is characterized in that magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and current is passed from the primary winding to the quaternary winding such that the direction of magnetic flux passage is opposite between the first and fourth columnar cores and between the second and third columnar cores, or that magnetic flux passes through the first and second columnar cores in the same longitudinal direction, and magnetic flux passes through the third and fourth columnar cores in the same longitudinal direction, and current is passed from the primary winding to the quaternary winding such that the direction of magnetic flux passage is opposite between the first and second columnar cores and between the third and fourth columnar cores.

[0016] In one embodiment, the secondary winding comprises a first and second separated secondary winding that bundle and circumfer the second and third columnar cores, and the tertiary winding comprises a first separated tertiary winding and a second separated tertiary winding that bundle and circumfer the first and second columnar cores, with the first separated secondary winding and the first separated tertiary winding connected in parallel, and the second separated secondary winding and the second separated tertiary winding connected in parallel.

[0017] In one embodiment, the quaternary winding comprises a first separated quaternary winding and a second separated quaternary winding, the first separated quaternary winding and the second separated quaternary winding bundle together and circumferentially surround the third columnar core and the fourth columnar core. [Effects of the Invention]

[0018] According to the present invention, the transformer used in a power conversion device can be made smaller. Alternatively, losses that occur in a power conversion device can be suppressed. [Brief explanation of the drawing]

[0019] [Figure 1] This diagram shows the configuration of a power conversion device according to one embodiment of the present invention. [Figure 2] This figure shows the time waveforms of voltage or current in each part. [Figure 3] This diagram shows the configuration of the primary / secondary transformers and the tertiary / quaternary transformers. [Figure 4] This is a diagram showing the configuration of a dual transformer. [Figure 5] This diagram illustrates the magnetic flux in a dual transformer. [Figure 6] This diagram shows the configuration of a dual transformer in a modified example. [Figure 7] This diagram illustrates the magnetic flux in a dual transformer. [Figure 8] This figure shows the configuration of a power conversion device according to a second embodiment of the present invention. [Figure 9] This diagram shows the configuration of a winding-separated primary / secondary transformer and a winding-separated tertiary / quaternary transformer. [Figure 10] This diagram shows the configuration of a winding-separated dual transformer. [Modes for carrying out the invention]

[0020] Embodiments of the present disclosure will be described with reference to the respective figures. The same components shown in multiple drawings are given the same reference numerals to simplify the description. Terms indicating directions such as "up" and "down" in this specification indicate the directions in the circuit diagram and do not limit the posture when each component is actually arranged. Also, ordinal numbers such as "primary" and "secondary" in this specification, and terms indicating the order of components such as "primary" and "secondary" are merely terms for convenience in distinguishing each component and do not limit the configuration, function, etc. of each component.

[0021] FIG. 1 shows the configuration of a power conversion device

[100] according to a first embodiment of the present invention. The power conversion device 100 includes a primary power converter 10P, an intermediate power converter 10M, and a secondary power converter 10S. The primary power converter 10P includes a primary switching circuit 12P and a primary winding L [ a ]. The intermediate power converter 10M includes an intermediate switching circuit 12M, a secondary winding L b and a tertiary winding L c [ a ]. The secondary power converter 10S includes a secondary switching circuit 12S and a quaternary winding L d [ a ].

[0022] The primary winding L a and the secondary winding L b are coupled to form a primary / secondary transformer T12. The tertiary winding L c and the quaternary winding L d are coupled to form a tertiary / quaternary transformer T34. The coupling between the pair of the primary winding L a and the secondary winding L b and the pair of the tertiary winding L c and the quaternary winding L d is small enough not to affect the operation of the power conversion device 100. Alternatively, the pair of the primary winding L a and the secondary winding L b and the pair of the tertiary winding L c and the quaternary winding L d are not coupled.

[0023] In Figure 1, the black dots attached to one end of the windings indicate the polarity of the winding. That is, when the current flowing through one of two interconnected windings changes, and an induced electromotive force appears with the black-dotted end of that winding as positive, an induced electromotive force will also be generated in the other winding, with the black-dotted end as positive.

[0024] In this embodiment, the secondary winding L b When the number of turns is set to 1, the primary winding L a The number of turns is 20. Also, the tertiary winding L c The winding has 4 turns, and the 4th winding L d The number of turns is 1. Primary winding L a , secondary winding L b , tertiary winding L c and the quaternary winding L d The number of turns may be increased while maintaining the ratio of 20:1:4:1. Furthermore, the ratio of turns for each winding may be changed according to the design value of the voltage output by each power converter.

[0025] The primary power converter 10P has a primary winding L a The primary switching circuit 12P comprises a primary capacitance section CP and a primary switching bridge BP as constituent elements. The primary capacitance section CP includes a series-connected upper split capacitor CDH and a series-connected lower split capacitor CDL. The primary switching bridge BP includes a series-connected high-side switching element SH and a series-connected low-side switching element SL.

[0026] These switching elements may be semiconductor switching elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). Here, two MOSFETs connected in series means that the source of one MOSFET is connected to the drain of the other MOSFET. Two IGBTs connected in series means that the emitter of one IGBT is connected to the collector of the other IGBT. Furthermore, when the switching element is a MOSFET, a parasitic diode with the anode connected to the source and the cathode connected to the drain may be included in the switching element. When the switching element is an IGBT, a parasitic diode with the anode connected to the emitter and the cathode connected to the collector may be included in the switching element. In this specification, switching elements are described as including parasitic diodes. The same applies to other switching elements shown in this specification.

[0027] The primary switching bridge BP and the primary capacitance section CP are connected in parallel. Primary winding L a It is connected between the connection point of the high-side switching element SH and the low-side switching element SL of the primary switching bridge BP and the connection point of the upper split capacitor CDH and the lower split capacitor CDL of the primary capacitance section CP.

[0028] The connection point between the upper split capacitor CDH and the lower split capacitor CDL of the primary capacitance unit CP is connected to the first positive terminal Tp1, and the end of the lower split capacitor CDL of the primary capacitance unit CP that is opposite to the upper split capacitor CDH (the lower end) is connected to the second negative terminal Tn2.

[0029] The intermediate power converter 10M has a secondary winding L b and tertiary winding L cIn addition, the intermediate switching circuit 12M includes an intermediate capacitance section CM and an intermediate switching bridge BM. The intermediate capacitance section CM comprises an upper split capacitor CDH and a lower split capacitor CDL connected in series. The primary switching bridge BP comprises a high-side switching element SH and a low-side switching element SL connected in series.

[0030] The intermediate switching bridge BM and the intermediate capacitance section CM are connected in parallel. Secondary winding L b and tertiary winding L c Each of these is connected between the connection point of the high-side switching element SH and the low-side switching element SL of the intermediate switching bridge BM and the connection point of the upper split capacitor CDH and the lower split capacitor CDL of the intermediate capacitance section CM. That is, the secondary winding L b and tertiary winding L c They are connected in parallel.

[0031] The upper end (top end) of the upper split capacitor CDH of the intermediate capacitance section CM, opposite to the lower split capacitor CDL, is connected to the second positive terminal Tp2, and the lower end (bottom end) of the lower split capacitor CDL, opposite to the upper split capacitor CDH, is connected to the second negative terminal Tn2.

[0032] The secondary power converter 10S has a fourth winding L d The secondary switching circuit 12S comprises a secondary capacitance section CS and a secondary switching bridge BS. The secondary capacitance section CS includes a series-connected upper split capacitor CDH and a series-connected lower split capacitor CDL. The secondary switching bridge BS includes a series-connected high-side switching element SH and a series-connected low-side switching element SL.

[0033] The secondary switching bridge BS and the secondary capacitance section CS are connected in parallel. The fourth winding L dIt is connected between the connection point of the high-side switching element SH and the low-side switching element SL of the secondary switching bridge BS and the connection point of the upper split capacitor CDH and the lower split capacitor CDL of the secondary capacitance section CS.

[0034] The upper end (top end) of the upper split capacitor CDH of the secondary capacitance section CS, opposite to the lower split capacitor CDL, is connected to the third positive terminal Tp3, and the lower end (bottom end) of the lower split capacitor CDL, opposite to the upper split capacitor CDH, is connected to the third negative terminal Tn3.

[0035] The operation of the power converter 100 will now be described. The high-side switching element SH and the low-side switching element SL in the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS alternately turn on and off. That is, when the high-side switching element SH is on, the low-side switching element SL is off, and when the high-side switching element SH is off, the low-side switching element SL is on. In addition, the high-side switching element SH and the low-side switching element SL in the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS repeatedly turn on and off with the same duty cycle. Here, the duty cycle is the ratio of the time the switching element is on to the switching period.

[0036] The primary power converter 10P will be described. A DC voltage V is applied between the first positive terminal Tp1 and the first negative terminal Tn1. A A voltage is applied. As a result, a DC voltage V is applied to the lower split capacitor CDL. A A voltage is applied. The operation of the primary switching bridge BP causes the primary winding L a An induced electromotive force is generated, and this induced electromotive force is applied to the upper split capacitor CDH.

[0037] The power transmitted between the primary power converter 10P and the intermediate power converter 10M is adjusted by changing the difference between the switching phase of the high-side switching element SH of the primary switching bridge BP and the switching phase of the high-side switching element SH of the intermediate switching bridge BM. The power transmitted between the primary power converter 10P and the intermediate power converter 10M is also adjusted by changing the duty cycle of the high-side switching element SH and the low-side switching element SL. Furthermore, the power transmitted between the intermediate power converter 10M and the secondary power converter 10S is adjusted by changing the difference between the switching phase of the high-side switching element SH of the intermediate switching bridge BM and the switching phase of the high-side switching element SH of the secondary switching bridge BS.

[0038] The intermediate capacitance section CM is charged according to the power transmitted from the primary power converter 10P to the intermediate power converter 10M and the power transmitted from the intermediate power converter 10M to the secondary power converter 10S. The secondary capacitance section CS is also charged according to the power transmitted from the intermediate power converter 10M to the secondary power converter 10S. Furthermore, the ratio between the terminal voltage of the upper split capacitor CDH and the terminal voltage of the lower split capacitor CDL in each capacitance section is determined by the duty cycle.

[0039] Figure 2(a) shows the primary winding L a Terminal voltage v a The time waveform is shown. Figure 2(b) shows the secondary winding L b Terminal voltage v b and tertiary winding L c Terminal voltage v c The time waveform is shown. Figure 2(c) shows the fourth winding L d Terminal voltage v dThe time waveforms are shown. Figures 2(a) to (c) correspond to the time waveforms of the control signals for the high-side switching element SH of the primary switching bridge BP, the high-side switching element SH of the intermediate switching bridge BM, and the high-side switching element SH of the secondary switching bridge BS, respectively. When this control signal is high, the high-side switching element SH is turned on, and when the control signal is low, the high-side switching element SH is turned off. The switching period of the high-side switching element SH and low-side switching element SL of each switching bridge is defined as T. The duty cycle of the low-side switching element SL is defined as D.

[0040] Figure 2(d) shows the primary winding L a Current i flowing into a The time waveform is shown. Figure 2(d) shows the secondary winding L b Current i flowing out from b This is shown, and Figure 2(e) shows the tertiary winding L c Current i flowing into c This is shown. Figure 2(f) shows the quaternary winding L d Current i flowing out from d This is shown. However, the primary winding L a Current i flowing into a This is from the primary switching bridge BP to the primary winding L a The direction of flow is considered positive. Secondary winding L b Current i flowing out from b This is the secondary winding L b The direction in which current flows from the intermediate switching bridge BM is defined as positive. Tertiary winding L c Current i flowing into c The intermediate switching bridge BM is connected to the tertiary winding L. c The direction of flow is considered positive. Fourth winding L d Current i flowing out from d This is the quaternary winding L d The direction in which current flows from the secondary switching bridge BS is considered positive.

[0041] Primary winding L aThe voltage v between the terminals a is from the minimum value -V A to the maximum value V A ·D / (1 - D) and oscillates. Since the duty ratio of the low-side switching element SL of the primary switching bridge BP is D, the voltage v a between the terminals of the primary winding L a is at the minimum value -V A for a time DT within one period T and at the maximum value V A ·D / (1 - D) for a time (1 - D)T.

[0042] [[ID=!17]] The voltage v b [[ID=!20]]between the terminals of the secondary winding L b and the voltage v c between the terminals of the tertiary winding L c is from the minimum value -(1 - D)V B to the maximum value D·V B and oscillates. Since the duty ratio of the low-side switching element SL of the intermediate switching bridge BM is D, the voltage v b between the terminals of the secondary winding L b and the voltage v<00000!82>between the terminals of the tertiary winding L c is at the minimum value -(1 - D)V B for a time DT within one period T and at the maximum value D·V B for a time (1 - D)T.

[0043] The voltage v d between the terminals of the quaternary winding L d is from the minimum value -(1 - D)V C to the maximum value D·V C and oscillates. Since the duty ratio of the low-side switching element SL of the secondary switching bridge BS is D, the voltage v d between the terminals of the quaternary winding L d is at the minimum value -(1 - D)V C for a time DT within one period T and at the maximum value D·V C for a time (1 - D)T.

[0044] The phase of the voltage v a between the terminals of the primary winding L a is that of the secondary winding L b It should be noted that there seems to be a formatting or content issue with the "!20" and "!82" in the original text which might need to be corrected in the source for a more accurate translation. Also, the "!17" might be an error in the original.The voltage v between the terminals b advances by θ1 with respect to the phase of the secondary winding L b The voltage v between the terminals b is -(1-D)V B and the voltage v between the terminals of the primary winding L a is V a When it is ·D / (1-D), the currents i A and i a increase and change from negative values to positive values. The voltage v between the terminals of the secondary winding L b is D·V b The voltage v between the terminals b is D·V B and the voltage between the terminals of the primary winding L a is V A When it is ·D / (1-D), the currents i a and i b become constant. The voltage between the terminals of the secondary winding L b is D·V B and the voltage between the terminals of the primary winding L a is -V A When it is, the currents i a and i b decrease and change from positive values to negative values.

[0045] The phase of the voltage v between the terminals of the fourth winding L d advances by θ2 with respect to the phase of the voltage v between the terminals of the third winding L d The voltage v between the terminals of the fourth winding L c is -(1-D)V c and the voltage between the terminals of the third winding L d is D·V d When it is, the currents i C and i c increase and change from negative values to positive values. The voltage v between the terminals of the fourth winding L B is D·V c and the voltage between the terminals of the third winding L d is D·V d When it is, the currents i d is D·V C and the voltage between the terminals of the third winding L c is D·V B When it is, the currents i c and i d become constant. The voltage v between the terminals of the fourth winding L d is dD·V C Therefore, the tertiary winding L c Terminal voltage v c ga-(1-D)V B When this is the case, the current i c and i d It decreases and changes from a positive value to a negative value.

[0046] The power transmitted from the primary power converter 10P to the intermediate power converter 10M is current i a and primary winding L a Terminal voltage v a It becomes the product of the two. The larger the phase difference θ1, the greater the current i. a As the increase and decrease in the phase difference θ1 become larger, the larger the phase difference θ1, the greater the power transmitted from the primary power converter 10P to the intermediate power converter 10M. Also, as the duty cycle D increases, the primary winding L a The maximum value V A • D / (1-D) becomes larger, and the power transmitted from the primary power converter 10P to the intermediate power converter 10M increases.

[0047] The power transmitted from the intermediate power converter 10M to the secondary power converter 10S is current i d and the 4th winding L d Terminal voltage v d It becomes the product of the two. The larger the phase difference θ2, the greater the current i. d As the increase and decrease in the phase difference θ2 become larger, the larger the phase difference θ2, the greater the power transmitted from the intermediate power converter 10M to the secondary power converter 10S.

[0048] Through the above operation, the power input from the first positive terminal Tp1 and the first negative terminal Tn1 is transmitted to the secondary power converter 10S via the primary power converter 10P and the intermediate power converter 10M, and output from the third positive terminal Tp3 and the third negative terminal Tn3.

[0049] In the above, the primary winding L a Terminal voltage v a The phase of the secondary winding L b Terminal voltage v bLeading by θ1 with respect to the phase, the 4th winding L d Terminal voltage v d The phase of the tertiary winding L c Terminal voltage v c The case where the phase is led by θ2 was explained. Primary winding L a Terminal voltage v a The phase of the secondary winding L b Terminal voltage v b The fourth winding L lags behind the phase of the d Terminal voltage v d The phase of the tertiary winding L c Terminal voltage v c If the phase lags, power transmission occurs in the reverse direction. In this case, the power input from the third positive terminal Tp3 and the third negative terminal Tn3 is transmitted to the primary power converter 10P via the secondary power converter 10S and the intermediate power converter 10M, and output from the first positive terminal Tp1 and the first negative terminal Tn1.

[0050] Furthermore, in the power transmission between the first positive terminal Tp1 and the first negative terminal Tn1, and the third positive terminal Tp3 and the third negative terminal Tn3, if there is a load fluctuation, the following operations may be performed. That is, the primary power converter 10P may store a portion of the transmitted power in the primary capacitance unit CP, or the charge accumulated by the primary capacitance unit CP may contribute to the transmitted power. Similarly, the intermediate power converter 10M may store a portion of the transmitted power in the intermediate capacitance unit CM, or the charge accumulated by the intermediate capacitance unit CM may contribute to the transmitted power. The secondary power converter 10S may store a portion of the transmitted power in the secondary capacitance unit CS, or the charge accumulated by the secondary capacitance unit CS may contribute to the transmitted power.

[0051] In the power converter 100 according to this embodiment, the duty cycle D and the primary winding L are as follows. a , secondary winding L b , tertiary winding L c and the quaternary winding L d The number of turns for each of the secondary windings L may be determined. bTerminal voltage v b The primary winding L a Terminal voltage v a When converted to this, the primary winding L a Terminal voltage v a And, secondary winding L b Terminal voltage v b To approximate or match the primary-side equivalent values, the duty cycle D, the number of turns of the primary winding La, and the secondary winding L are used. b The number of turns is determined. Also, the quaternary winding L d The voltage between the terminals is measured in the tertiary winding L c Terminal voltage v c When converted to this, the tertiary winding L c Terminal voltage v c And the quaternary winding L d Terminal voltage v d The number of turns of the tertiary winding Lc and the quaternary winding L are set so that the tertiary side equivalent value is approximate or matches. d The number of turns is determined.

[0052] Experiments and simulations have confirmed that by defining the duty cycle D and the number of turns in each winding, the frequency of hard switching and the frequency of soft switching in each switching element decreases. Here, soft switching refers to the switching element turning on when the voltage applied to the switching element is 0 or close to 0. Hard switching refers to switching that is not soft switching. In the case of a switching element that includes a parasitic diode, the switching that turns on when the parasitic diode is in a forward bias state is soft switching.

[0053] As a first example of operation, we consider the case where current flows into the connection point between the high-side switching element SH and the low-side switching element SL of a switching bridge. Starting from a state where the high-side switching element SH is off and the low-side switching element SL is on, both the high-side switching element SH and the low-side switching element SL turn off, causing the parasitic diode in the high-side switching element SH to conduct. Furthermore, when the high-side switching element SH turns on and the low-side switching element SL turns off, soft switching occurs.

[0054] As a second example of operation, we will consider the case where current flows out from the connection point between the high-side switching element SH and the low-side switching element SL of the switching bridge. Starting from a state where the high-side switching element SH is ON and the low-side switching element SL is OFF, both the high-side switching element SH and the low-side switching element SL turn OFF, causing the parasitic diode in the low-side switching element SL to conduct. Furthermore, when the high-side switching element SH turns OFF and the low-side switching element SL turns ON, soft switching occurs.

[0055] In the example shown in Figure 2, soft switching is performed in the primary switching bridge BP, the intermediate switching bridge BM, and the secondary switching bridge BS. For example, as shown in Figures 2(b), (e), and (f), current i b The current i is positive. b The current i flows into the intermediate switching bridge BM, c The current i is negative. cWhen current flows into the intermediate switching bridge BM, the intermediate switching bridge BM changes from a state where the high-side switching element SH is off and the low-side switching element SL is on, to a state where both the high-side switching element SH and the low-side switching element SL are off, and then the high-side switching element SH is on and the low-side switching element SL is off. As a result, soft switching occurs in the intermediate switching bridge BM. This operation corresponds to the first example of operation described above.

[0056] Also, current i b The current i is negative. b The current i flows out from the intermediate switching bridge BM. c The current i is positive. c Furthermore, when current flows out from the intermediate switching bridge BM, the intermediate switching bridge BM changes from a state where the high-side switching element SH is on and the low-side switching element SL is off, to a state where both the high-side switching element SH and the low-side switching element SL are off, and then the high-side switching element SH is off and the low-side switching element SL is on. As a result, soft switching occurs in the intermediate switching bridge BM. This operation corresponds to the second example of operation described above.

[0057] In the embodiment shown in Figure 1, when a voltage of 200V or more and 900V or less is applied to the first positive terminal Tp1 and the first negative terminal Tn1, the terminal voltage of the primary capacitance section CP in the primary power converter 10P is boosted to 1000V according to the duty cycle D, and the primary winding L a and secondary winding L b Depending on the turns ratio, a voltage of 48V appears in the intermediate capacitance section CM of the intermediate power converter 10M. As a result, the voltage V output from the second positive terminal Tp2 and the second negative terminal Tn2 B The voltage is 48V.

[0058] Also, the tertiary winding L c and the 4th winding L dDepending on the turns ratio, a voltage of 12V appears in the secondary capacitance section CS of the secondary power converter 10S. As a result, the voltage V output from the third positive terminal Tp3 and the third negative terminal Tn3 is C It is 12V.

[0059] Thus, the primary winding L a and secondary winding L b Depending on the turns ratio and duty cycle D, the voltage between the first positive terminal Tp1 and the first negative terminal Tn1 is stepped down and applied to the intermediate capacitance section CM of the intermediate power converter 10M. The terminal voltage of the intermediate capacitance section CM is determined by the tertiary winding L c and the 4th winding L d The voltage is stepped down according to the turns ratio and applied to the secondary capacitance section CS of the secondary power converter 10S.

[0060] In other words, the voltages at the first positive terminal Tp1 and the first negative terminal Tn1 are stepped down in two stages and output from the third positive terminal Tp3 and the third negative terminal Tn3. In this way, the primary winding L a and secondary winding L b The primary / secondary transformer T12 and the tertiary winding L are composed of these components. c and the quaternary winding L d The stepwise step-down voltage reduction achieved by the tertiary / quaternary transformer T34, which is composed of these elements, reduces the volume occupied by the transformer compared to a case where the voltage reduction is achieved by a single transformer.

[0061] In the power converter 100 according to this embodiment, the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d The coupling between the set is small enough not to affect the operation of the power converter 100. Alternatively, the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d There is no connection between the pairs. This ensures proper pressure reduction.

[0062] Furthermore, the intermediate power converter 10M controls the current i flowing into the intermediate switching bridge BM. b The size and the current i flowing out from the intermediate switching bridge BM c They may be designed so that their magnitudes are equal. In this case, the currents flowing through the high-side switching element SH and the low-side switching element SL in the intermediate switching bridge BM cancel each other out or are suppressed, and conduction losses are suppressed.

[0063] Next, we will explain an example of transformer configuration. The upper part of Figure 3 shows the configuration of the primary / secondary transformer T12. The lower part of Figure 3 shows the configuration of the tertiary / quaternary transformer T34. The primary / secondary transformer T12 and the tertiary / quaternary transformer T34 are configured separately. The primary / secondary transformer T12 has a primary winding L a , secondary winding L b The structure also includes a gapped annular core 14. The gapped annular core 14 is formed from a magnetic material that is formed in an annular shape. The gapped annular core 14 has a gap 14G that crosses the magnetic material that extends in the circumferential direction. The cross-section of the gapped annular core 14 perpendicular to the circumferential direction may be circular, substantially elliptical, polygonal, or the like.

[0064] Primary winding L a and secondary winding L b The conductors that make up the winding are wound around a magnetic material that extends in the circumferential direction. Primary winding L a This is the secondary winding L b In addition to functioning as an element that transmits power, it also functions as a reactor that boosts or bucks voltage. Therefore, the primary winding L a The current flowing through it contains a DC component, and a DC magnetic flux passes through the gapped annular core 14. Therefore, the gap 14G provided by the gapped annular core 14 prevents the gapped annular core 14 from becoming magnetically saturated by the DC magnetic flux.

[0065] The 3rd / 4th transformer T34 has a 3rd winding L c , quaternary winding L dand an annular core 16. The annular core 16 is formed of a magnetic material formed in an annular shape. The cross section perpendicular to the circumferential direction may be circular, substantially elliptical, polygonal, etc. Tertiary winding L c and the quaternary winding L d The conductors constituting the core are wound around a magnetic material that extends in the circumferential direction. Although the annular core 16 shown in Figure 3 does not have a gap, a gap, which is an air gap that crosses the magnetic material that extends in the circumferential direction, may be provided.

[0066] The primary / secondary transformer T12 and the tertiary / quaternary transformer T34 are configured separately, resulting in the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d The coupling between the set is small enough not to affect the operation of the power converter 100. Alternatively, the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d It does not combine with the set.

[0067] Figure 4 shows the configuration of a dual transformer TD, which integrates the primary / secondary transformer T12 and the tertiary / quaternary transformer T34. The left side of Figure 4 shows a side view, and the right side shows a cross-sectional view along line AA shown on the left. The dual transformer TD has a primary winding L a , secondary winding L b The system also includes a four-legged core 30. The four-legged core 30 comprises a first columnar core 22-1, a second columnar core 22-2, a third columnar core 22-3, a fourth columnar core 22-4, a first common core 18, and a second common core 20. Each of the first columnar core 22-1, the second columnar core 22-2, the third columnar core 22-3, and the fourth columnar core 22-4 has a gap 22G formed across the magnetic material extending in the longitudinal direction. These gaps 22G may not be formed.

[0068] Each of the first common core 18 and the second common core 20 is formed in a plate shape. The first common core 18 and the second common core 20 may be formed in other shapes. One end of each of the first columnar cores 22-1 to the fourth columnar core 22-4 is connected to the first common core 18, and the other end is connected to the second common core 20. Each of the first columnar cores 22-1 to the fourth columnar core 22-4 is formed in a rectangular prism shape. Each of the first columnar cores 22-1 to the fourth columnar core 22-4 may be cylindrical, substantially cylindrical, or a polygonal prism other than a rectangular prism. The first columnar cores 22-1 to the fourth columnar core 22-4, the first common core 18, and the second common core 20 may be integrally formed from a magnetic material.

[0069] Looking from the first common core 18 side to the second common core 20 side, the first columnar cores 22-1 to the fourth columnar cores 22-4 are arranged in this order clockwise. Primary winding L a The first columnar core 22-1 and the fourth columnar core 22-4 are bundled together and arranged in a circle, and the secondary winding L b The second columnar core 22-2 and the third columnar core 22-3 are bundled together and circled. The tertiary winding Lc bundles the first columnar core 22-1 and the second columnar core 22-2 and circled, and the quaternary winding L d This structure consists of the third columnar core 22-3 and the fourth columnar core 22-4 bundled together and encircling each other.

[0070] On the left side of Figure 5 is the primary winding L. a and secondary winding L b When magnetic flux is emitted from the first columnar core 22-1 to the fourth columnar core 22-4, the direction of the magnetic flux passing through each of them is shown. On the right side of Figure 5 is the tertiary winding L c and the quaternary winding L d When magnetic flux is emitted from the device, the direction of the magnetic flux passing through each of the first to fourth columnar cores is shown. A symbol with a dot in the center of a circle indicates magnetic flux directed from the drawing surface towards the reader, while a symbol with an X inside a circle indicates magnetic flux directed from the reader towards the drawing surface.

[0071] The left side of Figure 5 shows the switching operation of the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS, where magnetic flux passes through the first columnar core 22-1 and the fourth columnar core 22-4 in the same longitudinal direction, and through the second columnar core 22-2 and the third columnar core 22-3 in the same longitudinal direction, and furthermore, the direction of magnetic flux passing through the first columnar core 22-1 and the fourth columnar core 22-4 is opposite to that of the second columnar core 22-2 and the third columnar core 22-3.

[0072] Primary winding L a and secondary winding L b The magnetic flux emitted from each of these passes through the first magnetic path Φ1, which sequentially passes through the first columnar core 22-1, the first common core 18, the second columnar core 22-2, and the second common core 20. Also, the primary winding L a and secondary winding L b The magnetic flux emitted from each of these also passes through the second magnetic path Φ2, which sequentially passes through the fourth columnar core 22-4, the first common core 18, the third columnar core 22-3, and the second common core 20. Primary winding L a and secondary winding L b Then, the magnetic fluxes generated by each link together via the first magnetic path Φ1 and the second magnetic path Φ2. As a result, the primary winding L a and secondary winding L b They combine.

[0073] Primary winding L a and secondary winding L b The direction of the magnetic flux emitted from each of the first columnar cores 22-1 and the second columnar core 22-2 is opposite. Therefore, this magnetic flux is directed around the tertiary winding L that bundles the first columnar core 22-1 and the second columnar core 22-2 together. c It does not link with the primary winding L. a and secondary winding L b The direction of the magnetic flux emitted from each of them is opposite for the third columnar core 22-3 and the fourth columnar core 22-4. Therefore, this magnetic flux is directed towards the quaternary winding L that bundles the third columnar core 22-3 and the fourth columnar core 22-4 together. dI will not engage with them.

[0074] This results in the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d The coupling between the set is small enough not to affect the operation of the power converter 100. Alternatively, the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d There is no connection between the pairs.

[0075] The right side of Figure 5 shows the switching operation when the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS switch, with magnetic flux passing through the first columnar core 22-1 and the second columnar core 22-2 in the same longitudinal direction, and magnetic flux passing through the third columnar core 22-3 and the fourth columnar core 22-4 in the same longitudinal direction, and furthermore, the direction of magnetic flux passing through the first columnar core 22-1 and the second columnar core 22-2 is opposite to that of the third columnar core 22-3 and the fourth columnar core 22-4.

[0076] Tertiary winding L c and the quaternary winding L d The magnetic flux emitted from each of these passes through the third magnetic path Φ3, which in turn passes through the first columnar core 22-1, the first common core 18, the fourth columnar core 22-4, and the second common core 20. Also, the tertiary winding L c and the quaternary winding L d The magnetic flux emitted from each of these also passes through the fourth magnetic path Φ4, which sequentially passes through the second columnar core 22-2, the first common core 18, the third columnar core 22-3, and the second common core 20. Tertiary winding L c and the quaternary winding L d Then, the magnetic fluxes generated by each link together via the third magnetic path Φ3 and the fourth magnetic path Φ4. As a result, the tertiary winding L c and the quaternary winding L d They combine.

[0077] Tertiary winding Lc and the quaternary winding L d The direction of the magnetic flux emitted from each of the first columnar cores 22-1 and the fourth columnar core 22-4 are opposite. Therefore, this magnetic flux is directed towards the primary winding L that bundles the first columnar core 22-1 and the fourth columnar core 22-4 together. a It does not link with the tertiary winding L. c and the quaternary winding L d The direction of the magnetic flux emitted from each of the second columnar cores 22-2 and the third columnar core 22-3 is opposite. Therefore, this magnetic flux is directed towards the secondary winding L that bundles the second columnar core 22-2 and the third columnar core 22-3 together. b I will not engage with them.

[0078] Therefore, the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d The coupling between the set is small enough not to affect the operation of the power converter 100. Alternatively, the primary winding L a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d There is no connection between the pairs.

[0079] Figure 6 shows the configuration of a modified dual transformer TDA. The upper part of Figure 6 shows a side view, and the lower part shows a cross-sectional view along the line BB shown in the upper part. The dual transformer TDA has a structure in which the first columnar cores 42-1 to the fourth columnar cores 42-4 are arranged in a row. One end of each of the first columnar cores 42-1 to the fourth columnar cores 42-4 is connected to the first common core 38, and the other end of each of the first columnar cores 42-1 to the fourth columnar cores 42-4 is connected to the second common core 40. The first columnar cores 42-1 to the fourth columnar cores 42-4, the first common core 38, and the second common core 40 may be integrally formed from a magnetic material. Figure 6 shows an example in which no gaps are provided between the first columnar core 42-1 and the fourth columnar core 42-4. However, gaps may be formed in any or all of the first columnar core 42-1 to the fourth columnar core 42-4 in a direction intersecting the longitudinal direction.

[0080] Primary winding L a ~4th winding L d The method of winding the conductors constituting the first columnar core 42-1 to the fourth columnar core 42-4 is the same as that of the dual transformer TD shown in Figures 4 and 5. That is, the primary winding L a This involves bundling the first columnar core 42-1 and the fourth columnar core 42-4 together and circling them, and the secondary winding L b This bundles the second columnar core 42-2 and the third columnar core 42-3 and surrounds them. Tertiary winding L c This involves bundling the first columnar core 42-1 and the second columnar core 42-2 together and circling them, forming a quaternary winding L d This structure consists of the third columnar core 42-3 and the fourth columnar core 42-4 bundled together and encircling each other.

[0081] Figure 6 shows how the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS switch when magnetic flux passes through the first columnar core 42-1 and the fourth columnar core 42-4 in the same longitudinal direction, and through the second columnar core 42-2 and the third columnar core 42-3 in the same longitudinal direction, and furthermore, when the direction of magnetic flux passing through the first columnar core 42-1 and the fourth columnar core 42-4 is opposite to that of the second columnar core 42-2 and the third columnar core 42-3.

[0082] Figure 7 shows how the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS switch when magnetic flux passes through the first columnar core 42-1 and the second columnar core 42-2 in the same longitudinal direction, and through the third columnar core 42-3 and the fourth columnar core 42-4 in the same longitudinal direction, and furthermore, when the direction of magnetic flux passing through the first columnar core 42-1 and the second columnar core 42-2 is opposite to that of the third columnar core 42-3 and the fourth columnar core 42-4.

[0083] The primary winding L is constructed using a principle similar to that of the dual transformer TD shown in Figures 4 and 5. a and secondary winding L b The magnetic flux emitted from the primary winding L a and secondary winding L b They are mutually linked, and the primary winding L a and secondary winding L b The magnetic flux emitted from each of these is directed to the tertiary winding L c and the quaternary winding L d It does not interlock with the tertiary winding L. c and the quaternary winding L d The magnetic flux emitted from is directed to the tertiary winding L c and the quaternary winding L d They are mutually linked, and the tertiary winding L c and the quaternary winding L d The magnetic flux emitted from each of them is transmitted to the primary winding L a and secondary winding L b It does not link with the primary winding L.a and secondary winding L b The set and the tertiary winding L c and the quaternary winding L d The coupling between the sets is small enough not to affect the operation of the power converter 100. Alternatively, the set of primary winding La and secondary winding Lb and tertiary winding L c and the quaternary winding L d There is no connection between the pairs.

[0084] Figure 8 shows the configuration of the power converter 102 according to the second embodiment. In the power converter 102, the secondary winding L in the power converter 100 shown in Figure 1 b This is the first separation secondary winding L b1 and the second separation secondary winding L b2 It is separated into two parts. Also, the tertiary winding L c This is the first separation tertiary winding L c1 and the second separation tertiary winding L c2 It is separated into the 4th winding L d This is the first separation fourth winding L d1 and the second separation fourth winding L d2 It is separated into two parts.

[0085] The primary power converter 50P consists of the primary switching circuit 52P and the primary winding L a It is equipped with an intermediate power converter 50M, an intermediate switching circuit 52M, and a first isolation secondary winding L b1 , Second separation secondary winding L b2 , 1st separation tertiary winding L c1 and the second separation tertiary winding L c2 It is equipped with a secondary power converter 50S, a secondary switching circuit 52S, and a first isolation fourth winding L d1 and the second separation fourth winding L d2 It is equipped with.

[0086] Primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 This constitutes the winding-separated primary / secondary transformer Td12. The first separated tertiary winding L c1 , second separation tertiary winding L c3, 1st separation 4th winding L d1 and the second separation fourth winding L d2 This constitutes the winding-separated tertiary / quaternary transformer Td34.

[0087] In this embodiment, the first separated secondary winding L b1 and the second separation secondary winding L b2 When each winding is considered to have one turn, the primary winding L a The number of turns is 20. Also, the first separated tertiary winding L c1 and the second separation tertiary winding L c2 Each of these has 4 turns, and the first separated fourth winding L d1 and the second separation fourth winding L d2 Each of these has one turn. Primary winding L a , First separation secondary winding L b1 , Second separation secondary winding L b2 , 1st separation tertiary winding L c1 , second separation tertiary winding L c2 and the first separation fourth winding L d1 and the second separation fourth winding L d2 The number of turns may be increased while maintaining the ratio of 20:1:4:1. Furthermore, the ratio of turns for each winding may be changed according to the design value of the voltage output by each power converter.

[0088] The intermediate power converter 50M has a first separation secondary winding L b1 , Second separation secondary winding L b2 , 1st separation tertiary winding L c1 and the second separation tertiary winding L c2 The intermediate switching circuit 52M comprises an intermediate switching bridge BM, an intermediate capacitance section CM, and an intermediate parallel capacitor PCM. The first isolated tertiary winding L c1 This is the first separation secondary winding L b1 It is connected in parallel to the second separation tertiary winding L c2 This is the second separation secondary winding L b2It is connected in parallel. The intermediate parallel capacitor PCM and the intermediate switching bridge BM are connected in parallel. One end (upper end) of the high-side switching element SH of the intermediate switching bridge BM that is not connected to the low-side switching element SL is connected to the first separation secondary winding L b1 It is connected to one end of the first separated secondary winding L. b1 The other end is connected to the second positive terminal Tp2. The end (lower end) of the low-side switching element SL of the intermediate switching bridge BM that is not connected to the high-side switching element SH is connected to the second separation secondary winding L b2 It is connected to one end of the second separation secondary winding L. b2 The other end is connected to the second negative terminal Tn2. An intermediate capacitance section CM is connected between the second positive terminal Tp2 and the second negative terminal Tn2. The connection point between the high-side switching element SH and the low-side switching element SL is connected to the upper split capacitor CDH and the lower split capacitor CDL. First separated secondary winding L b1 and the second separation secondary winding L b2 This is the primary winding L a It is connected.

[0089] Furthermore, the second positive terminal Tp2 and the second negative terminal Tn2 may be connected to both ends of the intermediate parallel capacitor PCM instead of both ends of the intermediate capacitance section CM. That is, the upper end of the intermediate parallel capacitor PCM may be connected to the second positive terminal Tp2, and the lower end of the intermediate parallel capacitor PCM may be connected to the second negative terminal Tn2.

[0090] The secondary power converter 50S has a first separation quaternary winding L d1 and the second separation fourth winding L d2 In addition, the secondary switching circuit 52S includes a secondary switching bridge BS, a secondary capacitance section CS, and a secondary parallel capacitor PCS as elements constituting the secondary switching circuit 52S. The secondary power converter 50S has the same configuration as the intermediate power converter 50M. First isolated quaternary winding L d1 and the second separation fourth winding L d2 These are the first separation secondary winding L, respectively.b1 and the second separated secondary winding L b2 corresponds. The secondary switching bridge BS corresponds to the intermediate switching bridge BM. The secondary capacitance section CS corresponds to the intermediate capacitance section CM. The secondary parallel capacitor PCS corresponds to the intermediate parallel capacitor PCM. The third positive terminal Tp3 and the third negative terminal Tn3 respectively correspond to the second positive terminal Tp2 and the second negative terminal Tn2. The first separated fourth winding L d1 is connected to the first separated tertiary winding L c1 and the second separated fourth winding L d2 is connected to the second separated tertiary winding L c2 .

[0091] Note that the third positive terminal Tp3 and the third negative terminal Tn3 may be connected to both ends of the intermediate parallel capacitor PCM instead of both ends of the intermediate capacitance section CM. That is, the upper end of the intermediate parallel capacitor PCM may be connected to the third positive terminal Tp3, and the lower end of the intermediate parallel capacitor PCM may be connected to the third negative terminal Tn3.

[0092] The configurations and operations of the intermediate power converter 50M and the secondary power converter 50S are the same as those of the primary circuit or the secondary circuit described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2018-148623), and thus detailed descriptions thereof are omitted.

[0093] Similar to the power conversion device 100 according to the first embodiment, in the power conversion device 102 according to the second embodiment, the following power transmission is performed. In each of the primary switching bridge BP, the intermediate switching bridge BM, and the secondary switching bridge BS, the high-side switching element SH and the low-side switching element SL are alternately turned on and off. By changing the difference between the switching phases of the high-side switching element SH and the low-side switching element SL included in the primary switching bridge BP and the switching phases of the high-side switching element SH and the low-side switching element SL included in the intermediate switching bridge BM, the power transmitted between the primary power converter 50P and the intermediate power converter 50M is adjusted. Similarly, by changing the difference between the switching phases of the high-side switching element SH and the low-side switching element SL included in the intermediate switching bridge BM and the switching phases of the high-side switching element SH and the low-side switching element SL included in the secondary switching bridge BS, the power transmitted between the intermediate power converter 50M and the secondary power converter 50S is adjusted.

[0094] In the power conversion device 102 according to the present embodiment, the duty ratio D of the low-side switching element SL and the primary winding L are as follows a , the first separated secondary winding L b1 , the second separated secondary winding L b2 , the first separated tertiary winding L c1 , the second separated tertiary winding L c2 , the first separated quaternary winding L d1 and the second separated quaternary winding L d2 may be determined for each. The voltage between the terminals of the first separated secondary winding L b1 , when converted to the voltage between the terminals of the primary winding L a , the voltage between the terminals of the primary winding L a and the primary-side conversion value of the voltage between the terminals of the first separated secondary winding L b1 are approximated or matched. The duty ratio D, the number of turns of the primary winding L a , the first separated secondary winding L b1The number of turns is determined. Second separation secondary winding L b2 The number of turns is also the first separation secondary winding L b1 It is determined in the same way as above.

[0095] Also, the first separation fourth winding L d1 The terminal voltage is measured in the first separation tertiary winding L c1 When converted to terminal voltage, the first separated tertiary winding L c1 The terminal voltage and the first separated fourth winding L d1 The first isolated tertiary winding L is configured such that the tertiary-side equivalent value of the terminal voltage is approximate or matches. c1 Number of turns, 1st separation 4th winding L d1 The number of turns is determined. Second separation tertiary winding L c2 and the second separation fourth winding L d2 The number of turns is also the same for the first separation tertiary winding L. c1 and the first separation fourth winding L d1 It is determined in the same way as above.

[0096] Experiments and simulations have confirmed that by determining the duty cycle D and the number of turns in each winding, the frequency of hard switching decreases and the frequency of soft switching increases in each switching element.

[0097] In the embodiment shown in Figure 8, when a voltage of 200V or more and 900V or less is applied to the first positive terminal Tp1 and the first negative terminal Tn1, the terminal voltage of the primary capacitance section CP is boosted to 1000V by the primary power converter 50P, and the primary winding L a and the first separation secondary winding L b1 The turns ratio and the primary winding L a and the second separation secondary winding L b2 Depending on the turns ratio, a voltage of 48V appears in the intermediate capacitance section CM of the intermediate power converter 50M. As a result, the voltage V output from the second positive terminal Tp2 and the second negative terminal Tn2 B The voltage is 48V.

[0098] Also, the first separation tertiary winding L c1 and the first separation fourth winding Ld1 The turns ratio and the second separation tertiary winding L c2 and the second separation fourth winding L d2 Depending on the turns ratio, a voltage of 12V appears in the secondary capacitance section CS of the secondary power converter 50S. As a result, the voltage V output from the third positive terminal Tp3 and the third negative terminal Tn3 is C It is 12V.

[0099] Thus, the primary winding L a and the first separation secondary winding L b1 The turns ratio and the primary winding L a and the second separation secondary winding L b2 Depending on the turns ratio, the voltage between the first positive terminal Tp1 and the first negative terminal Tn1 is stepped down and applied to the intermediate capacitance section CM of the intermediate power converter 50M. The terminal voltage of the intermediate capacitance section CM is applied to the first separation tertiary winding L c1 and the first separation fourth winding L d1 The turns ratio and the second separation tertiary winding L c2 and the second separation fourth winding L d2 The voltage is stepped down according to the turns ratio and applied to the secondary capacitance section CS of the secondary power converter 50S.

[0100] In other words, the voltages at the first positive terminal Tp1 and the first negative terminal Tn1 are stepped down in two stages and output from the third positive terminal Tp3 and the third negative terminal Tn3. In this way, the stepwise step-by-step

[0101] In the power converter 102 according to this embodiment, the primary winding L a , First separation secondary winding L b 1st and 2nd Separation Secondary Winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 and the second separation fourth winding L d2The coupling between the set is small enough not to affect the operation of the power converter 100. Alternatively, the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 and the second separation fourth winding L d2 It does not combine with the other set. This ensures appropriate voltage reduction.

[0102] Also, the first separation secondary winding L b1 and the second separation secondary winding L b2 The first and third windings L are joined together. c1 and the second separation tertiary winding L c2 These are coupled. Based on these couplings, the mutual inductance and the capacitance of the intermediate parallel capacitor PCM form a filter, suppressing the ripple output from the second positive terminal Tp2 and the second negative terminal Tn2. First isolated quaternary winding L d1 and the second separation fourth winding L d2 These terminals are coupled, and a filter is formed by the mutual inductance based on this coupling and the capacitance of the secondary parallel capacitor PCS, suppressing the ripple output from the third positive terminal Tp3 and the third negative terminal Tn3.

[0103] Next, we will explain an example of transformer configuration. The upper part of Figure 9 shows the configuration of a winding-separated primary / secondary transformer Td12. The lower part of Figure 9 shows the configuration of a winding-separated tertiary / quaternary transformer Td34. The winding-separated primary / secondary transformer Td12 and the tertiary / quaternary transformer Td34 are configured separately. The winding-separated primary / secondary transformer Td12 has a primary winding L a , First separation secondary winding L b1 , Second separation secondary winding L b2 and a gapped annular core 14. Primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2The conductors constituting this winding are wound around a magnetic material extending circumferentially within the gapped annular core 14. Primary winding L a This is the first separation secondary winding L b1 and the second separation secondary winding L b2 In addition to functioning as an element that transmits power, it also functions as a reactor that boosts or bucks voltage. Therefore, the primary winding L a The current flowing through it contains a DC component, and a DC magnetic flux passes through the gapped annular core 14. Therefore, the gap 14G provided by the gapped annular core 14 prevents the gapped annular core 14 from becoming magnetically saturated by the DC magnetic flux.

[0104] The winding-separated tertiary / quaternary transformer Td34 has a first separated tertiary winding L c1 , second separation tertiary winding L c2 , 1st separation 4th winding L d1 , second separation fourth winding L d2 and an annular core 16. First separated tertiary winding L c1 , second separation tertiary winding L c2 , 1st separation 4th winding L d1 and the second separation fourth winding L d2 The conductors that make up the structure are wound around a magnetic material that extends in the circumferential direction.

[0105] The winding-separated primary / secondary transformer Td12 and the winding-separated tertiary / quaternary transformer Td34 are configured separately, so the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 and the second separation fourth winding L d2 The coupling between the set is small enough not to affect the operation of the power converter 102. Alternatively, the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1and the second separation fourth winding L d2 It does not combine with the set.

[0106] Figure 10 shows a winding-separated primary / secondary transformer L d12 And, winding-separated tertiary / quaternary transformer L d34 The configuration of a winding-separated dual transformer TDB that integrates the two is shown. The left side of Figure 10 shows a side view, and the right side shows a cross-sectional view along line AA shown on the left. The winding-separated dual transformer TDB has a primary winding L a , First separation secondary winding L b1 , Second separation secondary winding L b2 , 1st separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separation 4th winding L d1 , second separation fourth winding L d2 It also features a four-legged core 30.

[0107] Primary winding L a This bundles the first columnar core 22-1 and the fourth columnar core 22-4 and surrounds them, forming the first separated secondary winding L b1 and the second separation secondary winding L b2 Each of these bundles together the second columnar core 22-2 and the third columnar core 22-3 and surrounds them. First separation tertiary winding L c1 and the second separation tertiary winding L c2 Each of these bundles together the first columnar core 22-1 and the second columnar core 22-2 and circles around them, forming the first separated fourth winding L d1 and the second separation fourth winding L d2 Each of these bundles together the third columnar core 22-3 and the fourth columnar core 22-4 and encircles them.

[0108] Similar to the power converter 100 according to the first embodiment, magnetic flux passes through the first columnar core 22-1 and the fourth columnar core 22-4 in the same longitudinal direction, and magnetic flux passes through the second columnar core 22-2 and the third columnar core 22-3 in the same longitudinal direction. Furthermore, the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS are switched so that the direction of magnetic flux passing through the first columnar core 22-1 and the fourth columnar core 22-4 is opposite to that of the second columnar core 22-2 and the third columnar core 22-3.

[0109] Furthermore, similar to the power converter 100 according to the first embodiment, magnetic flux passes through the first columnar core 22-1 and the second columnar core 22-2 in the same longitudinal direction, and magnetic flux passes through the third columnar core 22-3 and the fourth columnar core 22-4 in the same longitudinal direction. In addition, the primary switching bridge BP, intermediate switching bridge BM, and secondary switching bridge BS are switched so that the direction of magnetic flux passing through the first columnar core 22-1 and the second columnar core 22-2 is opposite to that of the third columnar core 22-3 and the fourth columnar core 22-4.

[0110] This results in the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 The coupling between the primary winding L and the second separated quaternary winding Ld2 is small enough not to affect the operation of the power converter 102. Alternatively, the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 and the second separation fourth winding L d2 It does not combine with the set.

[0111] In this embodiment as well, a dual transformer having a structure in which the first columnar core 42-1 to the fourth columnar core 42-4 are arranged in a row may be used, as shown in the dual transformer TDA in Figure 6. Primary winding L a , First separation secondary winding L b1 , Second separation secondary winding L b 2. First separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separation 4th winding L d1 and the second separation fourth winding L d2 The method of winding the conductors constituting the first columnar core 42-1 to the fourth columnar core 42-4 is the same as that of the dual transformer TDA shown in Figure 6. That is, the primary winding L a This bundles the first columnar core 42-1 and the fourth columnar core 42-4 and surrounds them, forming the first separated secondary winding L b1 and the second separation secondary winding L b2 Each of these bundles together the second columnar core 42-2 and the third columnar core 42-3 and surrounds them. First separation tertiary winding L c1 and the second separation tertiary winding L c2 Each of these bundles together the first columnar core 42-1 and the second columnar core 42-2 and circles around them, forming the first separated fourth winding L d1 and the second separation fourth winding L d2 Each of these consists of a bundle of the third columnar core 42-3 and the fourth columnar core 42-4, which are arranged in a circle.

[0112] The primary winding L is constructed using a principle similar to that of the dual transformer TDA shown in Figure 6. a and the first separated secondary winding L b1 The magnetic flux emitted from the primary winding L a and the first separated secondary winding L b1 They are mutually linked. Similarly, the primary winding L a and the second separation secondary winding L b2 The magnetic flux emitted from the primary winding L a and the second separation secondary winding L b2 They interlock with each other. Primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2The magnetic flux emitted from each of them is directed to the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separation 4th winding L d1 and the second separation fourth winding L d2 It does not interlock with the first separation tertiary winding L. c1 and the first separation fourth winding L d1 The magnetic flux emitted from the first separation tertiary winding L c1 and the first separation fourth winding L d1 They interlock with each other. Similarly, the second separation tertiary winding L c2 and the second separation fourth winding L d2 The magnetic flux emitted from the second separation tertiary winding L c2 and the second separation fourth winding L d2 They are mutually linked. First separation tertiary winding Lc1, second separation tertiary winding L c2 , 1st separation 4th winding L d1 and the second separation fourth winding L d2 The magnetic flux emitted from each of these is distributed to the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 Do not engage in chain contact.

[0113] This results in the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 and the second separation fourth winding L d2 The coupling between the set is small enough not to affect the operation of the power converter 102. Alternatively, the primary winding L a , First separation secondary winding L b1 and the second separation secondary winding L b2 The set and the first separation tertiary winding L c1 , second separation tertiary winding L c2 , 1st separated 4 windings L d1 and the second separation fourth winding L d2 It does not combine with the set.

[0114] [Configuration of the present invention] Configuration 1: A secondary winding coupled to a primary winding to which a primary switching circuit is connected, A switching bridge to which the secondary winding is connected, A capacitor unit connected to the switching bridge, A tertiary winding connected in parallel to the secondary winding and coupled to a quaternary winding to which a secondary switching circuit is connected, and comprising: The switching bridge switches the voltage output by the capacitor unit and applies it to the secondary winding and the tertiary winding, The combination of the primary winding and the secondary winding and the combination of the tertiary winding and the quaternary winding do not couple or have a structure that suppresses mutual coupling. A power converter characterized by this. Configuration 2: The power converter according to Configuration 1, The switching bridge, Comprises two switching elements connected in series, The capacitor unit, Is connected in parallel to the switching bridge and comprises two divided capacitors connected in series, One end of the secondary winding is connected to the connection point of the two switching elements included in the switching bridge, The other end of the secondary winding is connected to the connection point of the two divided capacitors included in the capacitor unit. A power converter characterized by this. Configuration 3: The power converter according to Configuration 1, The switching bridge, Comprises two switching elements connected in series, The capacitor unit, Is connected in parallel to the switching bridge and comprises two divided capacitors connected in series, The secondary winding comprises a first separated secondary winding connected between one end of the switching bridge and one end of the capacitor unit, and a second separated secondary winding connected between the other end of the switching bridge and the other end of the capacitor unit, The tertiary winding comprises a first isolated tertiary winding connected in parallel to the first isolated tertiary winding, and a second isolated tertiary winding connected in parallel to the second isolated tertiary winding. A power converter characterized in that the connection point of the two switching elements of the switching bridge is connected to the connection point of the two divider capacitors of the capacitance section. Configuration 4: A power converter as described in configuration 1 or configuration 2, The primary winding to the fourth winding constitute the transformer. The aforementioned transformer In addition to the primary windings to the quaternary windings, the device comprises a first columnar core, a second columnar core, a third columnar core, and a fourth columnar core, a first common core to which one end of each of the first columnar cores to the fourth columnar core is connected, and a first common core to which the other end of each of the first columnar cores to the fourth columnar core is connected. The primary winding bundles the first columnar core and the fourth columnar core together and wraps around them. The secondary winding bundles the second columnar core and the third columnar core together and wraps around them. The tertiary winding bundles the first columnar core and the second columnar core together and wraps around them. The aforementioned fourth winding bundles the third columnar core and the fourth columnar core together and wraps around them. The primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and fourth columnar cores in the same longitudinal direction, and magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and the direction of magnetic flux passage is opposite between the first and fourth columnar cores and between the second and third columnar cores, or A power converter characterized in that a magnetic flux passing through the first columnar core and the second columnar core in the same longitudinal direction passes through the third columnar core and the fourth columnar core, and the primary switching circuit, the switching bridge, and the secondary switching circuit switch such that the direction of magnetic flux passing through the first columnar core and the second columnar core is opposite to the direction of magnetic flux passing through the third columnar core and the fourth columnar core. Configuration 5: The power converter described in configuration 3, The primary winding to the fourth winding constitute the transformer. The aforementioned transformer In addition to the primary windings to the quaternary windings, the device comprises a first columnar core, a second columnar core, a third columnar core, and a fourth columnar core, a first common core to which one end of each of the first to fourth columnar cores is connected, and a second common core to which the other end of each of the first to fourth columnar cores is connected. The primary winding bundles the first columnar core and the fourth columnar core together and wraps around them. The first and second separated secondary windings bundle the second and third columnar cores together and wrap around them. The first tertiary winding and the second tertiary winding bundle the first columnar core and the second columnar core together and wrap around them. The aforementioned fourth winding bundles the third columnar core and the fourth columnar core together and wraps around them. The primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and fourth columnar cores in the same longitudinal direction, and magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and the direction of magnetic flux passage is opposite between the first and fourth columnar cores and between the second and third columnar cores, or A power converter characterized in that a magnetic flux passing through the first columnar core and the second columnar core in the same longitudinal direction passes through the third columnar core and the fourth columnar core, and the primary switching circuit, the switching bridge, and the secondary switching circuit switch such that the direction of magnetic flux passing through the first columnar core and the second columnar core is opposite to the direction of magnetic flux passing through the third columnar core and the fourth columnar core. Configuration 6: The power converter described in configuration 5, The aforementioned quaternary winding comprises a first separated quaternary winding and a second separated quaternary winding. A power converter characterized in that the first separated quaternary winding and the second separated quaternary winding bundle and circumfer the third columnar core and the fourth columnar core. Composition 7: A power converter described in any one of configurations 1 to 6, The difference between the phase of the voltage applied by the primary switching circuit to the primary winding and the phase of the voltage applied by the switching bridge to the secondary winding, A power converter characterized in that the power transmitted between the primary switching circuit and the secondary switching circuit is adjusted by adjusting the difference between the phase of the voltage applied by the switching bridge to the tertiary winding and the phase of the voltage applied by the secondary switching circuit to the quaternary winding. Composition 8: A first columnar core, a second columnar core, a third columnar core, and a fourth columnar core, A first common core, to which one end of each of the first columnar core and the fourth columnar core is connected, A second common core is formed by connecting the other ends of the first columnar core to the fourth columnar core, A primary winding that bundles the first columnar core and the fourth columnar core together and circles around them, A secondary winding that bundles the second columnar core and the third columnar core together and encircles them, A tertiary winding that bundles the first columnar core and the second columnar core together and encircles them, The device comprises a quaternary winding that bundles the third columnar core and the fourth columnar core together and wraps around them, A transformer characterized in that magnetic flux passes through the first and fourth columnar cores in the same longitudinal direction, magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and current is passed from the primary winding to the quaternary winding such that the direction of magnetic flux passing through the first and fourth columnar cores is opposite to that of the second and third columnar cores, or a transformer characterized in that magnetic flux passes through the first and second columnar cores in the same longitudinal direction, magnetic flux passes through the third and fourth columnar cores in the same longitudinal direction, and current is passed from the primary winding to the quaternary winding such that the direction of magnetic flux passing through the first and second columnar cores is opposite to that of the third and fourth columnar cores. Composition 9: The transformer described in configuration 8, The secondary winding comprises a first separation secondary winding and a second separation secondary winding that bundle and circumfer the second columnar core and the third columnar core, The tertiary winding comprises a first separating tertiary winding and a second separating tertiary winding that bundle and circumfer the first columnar core and the second columnar core, The first isolated secondary winding and the first isolated tertiary winding are connected in parallel. A transformer characterized in that the second isolated secondary winding and the second isolated tertiary winding are connected in parallel. Configuration 10: The power converter described in configuration 9, The aforementioned quaternary winding comprises a first separated quaternary winding and a second separated quaternary winding. A transformer characterized in that the first isolated quaternary winding and the second isolated quaternary winding bundle and circumfer the third columnar core and the fourth columnar core. [Explanation of Symbols]

[0115] 10P, 50P Primary Power Converters, 10M, 50M Intermediate Power Converters, 10S, 50S Secondary Power Converters, 12P, 52P Primary Switching Circuits, 12M, 52M Intermediate Switching Circuits, 12S, 52S Secondary Switching Circuits, 14 Gap-type Ring Cores, 14G, 22G Gap Cores, 16 Ring Cores, 18 First Common Core, 20 Second Common Core, 22-1~22-4, 42-1~42-4 First Columnar Cores~Fourth Columnar Cores, 30 Four-legged Cores, 100, 102 Power Converters, L a Primary winding, L b Secondary winding, L b1 First separation secondary winding, L b2 Second separation secondary winding, L c Third winding, L c1 First separation tertiary winding, L c2 Second separation tertiary winding, L d Fourth winding, L d1 First separation fourth winding, L d2 Second isolated quaternary winding, BP primary switching bridge, BM intermediate switching bridge, BS secondary switching bridge, CP primary capacitance section, CM intermediate capacitance section, CS secondary capacitance section, SH high-side switching element, SL low-side switching element, CDH upper split capacitor, CDL lower split capacitor, Tp1 first positive terminal, Tn1 first negative terminal, Tp2 second positive terminal, Tn2 second negative terminal, Tp3 third positive terminal, Tn3 third negative terminal, T12 primary / secondary transformer, T34 tertiary / quaternary transformer, TD, TDA dual transformer, Td12 winding-separated primary / secondary transformer, Td34 winding-separated tertiary / quaternary transformer, TDB winding-separated dual transformer.

Claims

1. A secondary winding coupled to the primary winding to which the primary switching circuit is connected, A switching bridge to which the aforementioned secondary winding is connected, A capacitance unit connected to the aforementioned switching bridge, The system comprises a tertiary winding connected in parallel to the secondary winding and coupled to a quaternary winding to which a secondary switching circuit is connected, The switching bridge switches the voltage output by the capacitance section and applies it to the secondary winding and the tertiary winding. A power converter characterized in that the set of the primary winding and the secondary winding is not coupled to the set of the tertiary winding and the quaternary winding, or has a structure that suppresses coupling between them.

2. A power converter according to claim 1, The aforementioned switching bridge is Equipped with two switching elements connected in series, The aforementioned capacitance section is The switching bridge is equipped with two divider capacitors connected in parallel and in series, One end of the secondary winding is connected to the connection point of the two switching elements of the switching bridge. A power converter characterized in that the other end of the secondary winding is connected to the connection point of the two divided capacitors provided in the capacitance section.

3. A power converter according to claim 1, The aforementioned switching bridge is Equipped with two switching elements connected in series, The aforementioned capacitance section is The switching bridge is equipped with two divider capacitors connected in parallel and in series, The secondary winding comprises a first isolated secondary winding connected between one end of the switching bridge and one end of the capacitance section, and a second isolated secondary winding connected between the other end of the switching bridge and the other end of the capacitance section. The tertiary winding comprises a first isolated tertiary winding connected in parallel to the first isolated tertiary winding, and a second isolated tertiary winding connected in parallel to the second isolated tertiary winding. A power converter characterized in that the connection point of the two switching elements of the switching bridge is connected to the connection point of the two divider capacitors of the capacitance section.

4. A power converter according to any one of claims 1 to 3, The difference between the phase of the voltage applied by the primary switching circuit to the primary winding and the phase of the voltage applied by the switching bridge to the secondary winding, A power converter characterized in that the power transmitted between the primary switching circuit and the secondary switching circuit is adjusted by adjusting the difference between the phase of the voltage applied by the switching bridge to the tertiary winding and the phase of the voltage applied by the secondary switching circuit to the quaternary winding.

5. A power converter according to claim 1 or claim 2, The primary winding to the fourth winding constitute the transformer. The aforementioned transformer In addition to the primary windings to the quaternary windings, the device comprises a first columnar core, a second columnar core, a third columnar core, and a fourth columnar core, a first common core to which one end of each of the first to fourth columnar cores is connected, and a first common core to which the other end of each of the first to fourth columnar cores is connected. The primary winding bundles the first columnar core and the fourth columnar core together and wraps around them. The secondary winding bundles the second columnar core and the third columnar core together and wraps around them. The tertiary winding bundles the first columnar core and the second columnar core together and wraps around them. The aforementioned quaternary winding bundles the third columnar core and the fourth columnar core together and wraps around them. The primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and fourth columnar cores in the same longitudinal direction, and magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and the direction of magnetic flux passage is opposite between the first and fourth columnar cores and between the second and third columnar cores, or A power converter characterized in that a magnetic flux passing through the first columnar core and the second columnar core in the same longitudinal direction passes through the third columnar core and the fourth columnar core, and the primary switching circuit, the switching bridge, and the secondary switching circuit switch such that the direction of magnetic flux passing through the first columnar core and the second columnar core is opposite to the direction of magnetic flux passing through the third columnar core and the fourth columnar core.

6. A power converter according to claim 3, The primary winding to the fourth winding constitute the transformer. The aforementioned transformer In addition to the primary windings to the quaternary windings, the device comprises a first columnar core, a second columnar core, a third columnar core, and a fourth columnar core, a first common core to which one end of each of the first to fourth columnar cores is connected, and a second common core to which the other end of each of the first to fourth columnar cores is connected. The primary winding bundles the first columnar core and the fourth columnar core together and wraps around them. The first and second separated secondary windings bundle the second and third columnar cores together and wrap around them. The first tertiary winding and the second tertiary winding bundle the first columnar core and the second columnar core together and wrap around them. The aforementioned quaternary winding bundles the third columnar core and the fourth columnar core together and wraps around them. The primary switching circuit, the switching bridge, and the secondary switching circuit switch such that magnetic flux passes through the first and fourth columnar cores in the same longitudinal direction, and magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and the direction of magnetic flux passage is opposite between the first and fourth columnar cores and between the second and third columnar cores, or A power converter characterized in that a magnetic flux passing through the first columnar core and the second columnar core in the same longitudinal direction passes through the third columnar core and the fourth columnar core, and the primary switching circuit, the switching bridge, and the secondary switching circuit switch such that the direction of magnetic flux passing through the first columnar core and the second columnar core is opposite to the direction of magnetic flux passing through the third columnar core and the fourth columnar core.

7. A power converter according to claim 6, The aforementioned quaternary winding comprises a first separated quaternary winding and a second separated quaternary winding. A power converter characterized in that the first separated quaternary winding and the second separated quaternary winding bundle and circumfer the third columnar core and the fourth columnar core.

8. A first columnar core, a second columnar core, a third columnar core, and a fourth columnar core, A first common core, to which one end of each of the first columnar core and the fourth columnar core is connected, A second common core is formed by connecting the other ends of the first columnar core to the fourth columnar core, A primary winding that bundles the first columnar core and the fourth columnar core together and circles around them, A secondary winding that bundles the second columnar core and the third columnar core together and encircles them, A tertiary winding that bundles the first columnar core and the second columnar core together and encircles them, The third columnar core and the fourth columnar core are bundled together and surrounded by a quaternary winding, A transformer characterized in that magnetic flux passes through the first and fourth columnar cores in the same longitudinal direction, magnetic flux passes through the second and third columnar cores in the same longitudinal direction, and current is passed from the primary winding to the quaternary winding such that the direction of magnetic flux passage is opposite between the first and fourth columnar cores and between the second and third columnar cores, or magnetic flux passes through the first and second columnar cores in the same longitudinal direction, magnetic flux passes through the third and fourth columnar cores in the same longitudinal direction, and current is passed from the primary winding to the quaternary winding such that the direction of magnetic flux passage is opposite between the first and second columnar cores and between the third and fourth columnar cores.

9. A transformer according to claim 8, The secondary winding comprises a first separation secondary winding and a second separation secondary winding that bundle and circumfer the second columnar core and the third columnar core, The tertiary winding comprises a first separating tertiary winding and a second separating tertiary winding that bundle and circumfer the first columnar core and the second columnar core, The first isolated secondary winding and the first isolated tertiary winding are connected in parallel. A transformer characterized in that the second isolated secondary winding and the second isolated tertiary winding are connected in parallel.

10. A power converter according to claim 9, The aforementioned quaternary winding comprises a first separated quaternary winding and a second separated quaternary winding. A transformer characterized in that the first separated quaternary winding and the second separated quaternary winding bundle and circumfer the third columnar core and the fourth columnar core.

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