WO2018235455A1 - Three-phase ac insulated switching power supply - Google Patents

Three-phase ac insulated switching power supply Download PDF

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Publication number
WO2018235455A1
WO2018235455A1 PCT/JP2018/018504 JP2018018504W WO2018235455A1 WO 2018235455 A1 WO2018235455 A1 WO 2018235455A1 JP 2018018504 W JP2018018504 W JP 2018018504W WO 2018235455 A1 WO2018235455 A1 WO 2018235455A1
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current
output end
transformer
input
electrode output
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PCT/JP2018/018504
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French (fr)
Japanese (ja)
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羽田　正二
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Ntn株式会社
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode

Definitions

  • the present invention relates to an isolated switching power supply that converts three-phase alternating current to direct current.
  • an isolated converter is known as a switching power supply for converting alternating current into direct current.
  • DC / DC converters are disposed after AC / DC conversion by rectifying the alternating current voltage with a rectifying circuit and smoothing with a smoothing capacitor, not limited to single phase and three phase.
  • Patent documents 1 to 7 Also known is a two-stage configuration in which a power factor correction device (PFC) and a DC / DC converter are combined to perform power factor correction.
  • Patent Documents 6 and 7 describe an apparatus for boosting and improving the power factor of a three-phase AC output of a wind power alternator.
  • the present invention has an object of efficiently performing power factor improvement and power conversion with a simple configuration in an insulating switching power supply to which a three-phase alternating current is input.
  • the present invention provides the following configuration.
  • symbol in parenthesis is a code
  • One aspect of the switching power supply of the present invention is (A) first, second and third input terminals (R, S, T) to which three-phase alternating current is input; (B) positive electrode output end (P) and negative electrode output end (N), (C) Each has a primary coil (Lr1, Ls1, Lt1) and a secondary coil (Lr2, Ls2, Lt2), and one end of each primary coil has the first, second and third input ends (R, S) , T) respectively connected to the first, second and third transformers (Tr, Ts, Tt), (D) Each current path between the other end of the primary coil (Lr1, Ls1, Lt1) of each of the first, second and third transformers (Tr, Ts, Tt) and the input side reference potential end (E) First, second and third switching elements (Qr, Qs, Qt) which are on / off controlled by one control signal (Vg) to conduct or interrupt (E) One end of the secondary coil (Lr2, Ls2, Lt2) of each of the
  • the configuration in an isolated switching power supply that receives a three-phase alternating current and performs power factor improvement and power conversion, the configuration can be simplified and the efficiency of the transformer can be improved.
  • FIG. 1 is a view schematically showing an example of the circuit configuration of the embodiment of the switching power supply according to the present invention.
  • FIGS. 2 (a) and 2 (b) are diagrams for explaining the power factor improvement action by the input three-phase alternating current and the switching operation.
  • FIG. 3 is a diagram schematically showing the flow of current during the on period in the T mode of the circuit configuration shown in FIG.
  • FIG. 4 is a diagram schematically showing the potential relationship of the on period on the secondary side of the circuit configuration shown in FIG.
  • FIG. 5 is a diagram schematically showing the flow of current during the off period in the T mode of the circuit configuration shown in FIG.
  • FIG. 6 is a diagram schematically showing the potential relationship of the off period on the secondary side of the circuit configuration shown in FIG.
  • FIG. 1 is a view schematically showing an example of a circuit configuration of an embodiment of the isolated switching power supply of the present invention.
  • the switching power supply of the present invention is a power conversion device that receives three-phase AC power output from an AC generator as input and outputs DC power to a load.
  • three-phase AC power is output from a Y-connected three-phase stator coil in the AC generator.
  • the switching power supply of the present invention is not only a power conversion device but also has a function as a power factor correction device.
  • the power factor correction device aims to make the power factor equal to 1 by making the waveform of the input current the same as that of the input voltage and making the phase match.
  • the switching power supply of the present invention is an insulating type that electrically isolates the input side from the output side.
  • three transformers Tr, Ts and Tt corresponding to each phase are provided.
  • Each of the three transformers Tr, Ts, Tt comprises one primary coil and one secondary coil. It is preferable to use three transformers Tr, Ts, and Tt having the same electromagnetic characteristics, and it is preferable to use a three-phase reactor.
  • the symbols Lr1, Ls1 and Lt1 indicate primary coils of the respective transformers, and the symbols Lr2, Ls2 and Lt2 indicate secondary coils of the respective transformers.
  • each coil is shown by a black circle.
  • a coil when referred to as “one end” and “the other end”, it means a combination of “winding start end” and “winding end” and a combination of “winding end” and “winding start”. Shall be included.
  • One end (in this example, the winding start end) of the primary coils Lr1, Ls1 and Lt1 of the transformer on the input side has three terminals to which a three-phase AC voltage is input: a first input end R, a second input end S and a first The three input terminals T are respectively connected.
  • each phase of the three-phase alternating current is referred to as an R phase, an S phase, and a T phase.
  • the symbol E indicates the input side reference potential end.
  • a positive electrode output terminal P and a negative electrode output terminal N which are two terminals to which a DC voltage is output, are provided.
  • the negative output end N is a secondary side reference potential end. An output voltage is applied to a load (not shown) connected between the positive electrode output terminal P and the negative electrode output terminal N, and an output current flows.
  • each of the three switching elements Qr, Qs, Qt is connected to the other end (in this example, the winding end) of the primary coil Lr1, Ls1, Lt1 of each transformer.
  • the other ends of the switching elements Qr, Qs, Qt are connected to the input side reference potential end E.
  • Each switching element Qr, Qs, Qt has a control end, and each control end conducts or cuts off the current path between the other end of the primary coils Lr1, Ls1, Lt1 and the input side reference potential end E. Each is on / off controlled.
  • the control ends of the three switching elements Qr, Qs, Qt are controlled by one common control signal Vg.
  • the control signal Vg is, for example, a PWM signal having a pulse waveform of a predetermined frequency and a duty ratio. That is, the three switching elements Qr, Qs, Qt are controlled to always be turned on and off at the same time.
  • the switching elements Qr, Qs, Qt are n-channel MOSFETs (hereinafter referred to as "FETQr”, “FETQs”, “FETQt”), one end is a drain, the other end is a source, and the control end is a gate. is there.
  • the control signal Vg is a voltage signal.
  • rectifying elements such as diodes serving as current return paths need to be connected in reverse parallel.
  • first, second and third capacitors are disposed between one end (in this example, the winding start end) of the secondary coils Lr2, Ls2 and Lt2 of each transformer and the negative output end N which is the secondary side reference potential end.
  • C1, C2, and C3 (hereinafter referred to as "sub capacitors") are connected to one another.
  • a smoothing capacitor C4 is connected between the positive electrode output terminal P and the negative electrode output terminal N.
  • first, second and third diodes D1 and D2 which are an example of rectifying elements , D3 are connected respectively.
  • the anodes of the diodes D1, D2 and D3 are connected to the other ends of the secondary coils Lr2, Ls2 and Lt2, respectively, and the cathodes are connected to the positive electrode output terminal P.
  • Each diode D1, D2, D3 conducts the current flowing from the other end of the secondary coil Lr2, Ls2, Lt2 of each transformer to the positive output terminal P when forward biased, and shuts off the current when reverse biased Do.
  • the diodes D1, D2 and D3 preferably have small forward voltage drop and operate at high speed.
  • fourth, fifth and sixth diodes D4, D5 and D6, which are an example of a rectifying element, are connected between the other end of the secondary coils Lr2, Ls2 and Lt2 of each transformer and the negative output end N, respectively. It is done.
  • the cathodes of the diodes D4, D5, D6 are connected to the other ends of the secondary coils Lr2, Ls2, Lt2, respectively, and the anodes are connected to the negative output terminal N.
  • Each of the diodes D4, D5, D6 conducts the current flowing from the negative electrode output end N to the other end of the secondary coil Lr2, Ls2, Lt2 of each transformer when forward biased, and blocks the current when reverse biased.
  • a control unit that generates a control signal Vg is included.
  • the magnitudes of the input voltage and the DC output voltage are detected, the duty ratio of the control signal Vg is determined based on the detected input voltage and output voltage, and the control signal Vg is generated based thereon. It is preferable to use PWMIC as a main part of the control unit.
  • the PWMIC controls, for example, a pulse-like control having a constant duty ratio by inputting a DC signal of a constant voltage corresponding to one determined duty ratio and a carrier triangular wave signal having a constant frequency to the comparator.
  • the signal Vg is output.
  • such a control signal Vg is referred to as a "constant duty ratio" control signal.
  • FIG. 2A shows voltage waveforms of R phase, S phase, and T phase of the input three-phase alternating current.
  • the phase having the highest potential and the phase having the lowest potential are sequentially switched at every phase of 120 °.
  • the frequency of the three-phase alternating current is, for example, about several Hz to 100 Hz in the case of an alternator for wind power generation.
  • the switching frequency that is, the frequency of the control signal Vg in FIG. 1 is several kHz to several hundreds kHz, which is sufficiently higher than the frequency of the three-phase alternating current.
  • T mode a period in which the T phase is at the lowest potential
  • R mode the period in which the R phase is at the lowest potential
  • S mode the period in which the S phase is at the lowest potential
  • the R phase has the highest potential in the first half of the period
  • the S phase has the highest potential in the second half.
  • an input current flows due to the voltage between the positive potential phase and the negative potential phase, and no current flows in the off period.
  • an inter-phase voltage between the R phase and the T phase is referred to as an “RT inter-phase voltage” or the like and denoted as “vrt”.
  • the input current flowing by the RT inter-phase voltage vrt is represented as "irt”.
  • FIG. 2B shows, as an example, the waveform of the PWM control signal at point A on the time axis t in FIG. 2A, the voltage between rt phases vrt, and between the first input end R and the third input end T.
  • the on current irt flowing through the is schematically shown. Since the switching frequency is sufficiently high compared to the frequency of the three-phase alternating current, the RT interphase voltage vrt in one on period can be regarded as a pulse-like constant voltage.
  • the value of the start point of the current irt in the on period is determined by the instantaneous value of the RT inter-phase voltage vrt at the start point of the on period. Since the instantaneous value of the RT inter-phase voltage vrt is scattered on the locus of the sine wave, the current irt flowing through the primary coil during the on period also draws the locus of the sine wave. This means that the input current is a sine wave in phase with the input voltage. Thereby, the power factor improvement on the primary side is realized.
  • a current path including an inductance to which a three-phase AC interphase voltage is applied is turned on / off by using a PWM control signal having a constant frequency and a duty ratio, whereby a sine whose phase matches the input voltage The input current of the wave can be obtained.
  • FIG. 3 schematically shows a current flow (dotted line with an arrow) in the on period in T mode in the circuit configuration shown in FIG. ing.
  • An input current irt flows in the following path in the primary coil of the transformer Tr due to the RT phase voltage vrt.
  • ⁇ Input current irt first input end R ⁇ transformer Tr primary coil ⁇ FET Qr ⁇ FET Qt ⁇ transformer Tt primary coil ⁇ third input end T
  • the input current ist flows through the primary coil of the transformer Ts in the following path due to the ST phase voltage vst.
  • the current returning to the input side such as the current flowing from the primary coil of the transformer Tt to the third input terminal T, is hereinafter referred to as “reflux”.
  • the other ends (in this example, the winding ends) of the secondary coils of the transformer Tr, Ts and Tt are respectively a point, b and c points, and the secondary coil of the transformer Tr, Ts and Tt Let one end (in this example, the winding start end) be point d, point e, and point f.
  • the positive electrode output end P is a point h
  • the negative electrode output end N is a point g.
  • the point h is also one end of the smoothing capacitor C4.
  • the point g is also a common end of the sub capacitors C1, C2, C3 and the smoothing capacitor C4, and is a secondary side reference potential end.
  • FIG. 4 is a diagram schematically showing the potential relationship between the point a to h on the transformer secondary side in the on period. The operation of the transformer secondary side in the on period will be described with reference also to FIG.
  • the sub-capacitors C1, C2, C3 and the smoothing capacitor C4 are charged with the voltages Vc1, Vc2, Vc3, VC4 at both ends respectively.
  • a potential relationship diagram of the on period shown in FIG. 4 is referred to.
  • the secondary coil a point of the transformer Tr is at the same potential as the secondary side reference potential end point g because the diode D4 conducts.
  • the electromotive force Vr of the transformer Tr exceeds the voltage VC1 across the sub capacitor C1
  • the current iron of the on period flows in the following path in the direction of charging the sub capacitor C1.
  • the secondary coil b of the transformer Ts has the same potential as the point g on the secondary side reference potential end because the diode D5 conducts.
  • Vs of the transformer Ts exceeds the voltage VC2 across the sub capacitor C2
  • the current ison of the on period flows in the following path in the direction of charging the sub capacitor C2.
  • an electromotive force Vt is generated in the secondary coil when reflux flows in the primary coil.
  • the electromotive force Vt has a low potential at the point f side and a high potential at the point c side, and is in the opposite direction to the transformer Tr and Ts. Since the diode D6 is reverse biased with respect to the electromotive force Vt, no current flows.
  • the current iton is supplied to the load. Therefore, the current iton corresponds to the forward current in the forward system.
  • the supply current to the load is also merged with the discharge current from the smoothing capacitor C4. Since the sub capacitor C3 is discharged by the current iton, the potential at the point f decreases by that amount, and the voltage VC3 across the sub capacitor C3 decreases.
  • the electromotive force Vt of the transformer Tt is determined by the magnitude of the reflux of the primary coil.
  • the potential at the point c does not exceed the potential at the point h (see the potential at the point c '). In this case, the current iton does not flow.
  • FIG. 5 schematically shows the current flow (dotted line with arrow) in the off period in T mode in the circuit configuration of FIG. is there.
  • FIG. 6 is a diagram schematically showing the potential relationship between the point a to h on the transformer secondary side in the off period. The operation on the secondary side of the off period will be described with reference also to FIG.
  • the back electromotive force Vr generated in the secondary coil of the transformer Tr is directed to a low potential on the point d side and a high potential on the a point side. Since the diode D4 is reverse biased with respect to the back electromotive force Vr, no current flows.
  • a potential relationship diagram of the off period shown in FIG. 6 is referred to.
  • the back electromotive force Vr causes the potential at the secondary coil a of the transformer Tr to rise with respect to the potential at the point d.
  • the diode D1 becomes forward biased and the current iroff flows in the following path.
  • ⁇ Current iroff transformer Tr secondary coil point a ⁇ diode D 1 ⁇ point h ⁇ load (or smoothing capacitor C 4) ⁇ point g ⁇ sub capacitor C 1 ⁇ transformer Tr secondary coil point d
  • the back electromotive force Vs generated in the secondary coil of the transformer Ts is directed to a low potential on the point e side and a high potential on the point b side. Since the diode D5 is reverse biased with respect to the back electromotive force Vs, no current flows.
  • a potential relationship diagram of the off period shown in FIG. 6 is referred to.
  • the diode D2 is forward biased
  • the current isoff flows in the following path.
  • ⁇ Current isoff transformer Ts secondary coil point b ⁇ diode D2 ⁇ point h ⁇ load (or smoothing capacitor C4) ⁇ point g ⁇ sub capacitor C2 ⁇ transformer Ts secondary coil point
  • the currents iroff and isoff in the off period flow in the direction of discharging the sub capacitors C1 and C2, respectively.
  • the currents iroff and isoff in the off period correspond to the flyback current in the flyback system.
  • the magnetic energy stored in the transformer is released, but in the case of this circuit, the energy stored in the sub capacitors C1 and C2 is released.
  • the potential at the point a when iroff flows is the sum of the voltage VC1 across the sub capacitor C1 and the back electromotive force Vr to the potential at the point g.
  • the potential at point b when isoff flows is the sum of the potential at point g, the voltage VC2 across the sub capacitor C2 and the back electromotive force Vs.
  • the sub capacitors C1 and C2 are discharged by the currents iroff and isoff respectively, so the potential at the point d and the potential at the point e decrease by that amount, and the voltages VC1 and VC2 decrease.
  • the back electromotive force generated in the secondary coil of the transformer Tr and Ts in the off period is suppressed by the voltages VC1 and VC2 charged in the sub capacitors C1 and C2 in the on period, so there is no sub capacitor C1 or C2 Smaller than the back electromotive force of As a result, the back electromotive force generated on the primary side of the transformer Tr, Ts also decreases, and the withstand voltage required for the FET Qr, FET Qs on the primary side is reduced.
  • the back electromotive force Vt generated in the secondary coil of the transformer Tt is in the direction of high potential at the point f side and low potential at the point c side, and is opposite to the transformer Tr and Ts. Since the diode D3 is reverse biased with respect to the back electromotive force Vt, no current flows.
  • the potential at point f rises relative to the potential at point c due to the back electromotive force Vt and the potential at point f exceeds the voltage VC3 across the sub capacitor C3, the current itoff flows in the following path to charge the sub capacitor C3.
  • Current itoff transformer Tt secondary coil f point ⁇ sub capacitor C3 ⁇ diode D6 ⁇ transformer Tt secondary coil c point
  • the operation of the off period of this circuit is summarized as follows.
  • the back electromotive force generated in the secondary coil in the off period is added to the voltage of the sub capacitor.
  • the added voltage exceeds the voltage of the smoothing capacitor, current flows in the load.
  • the back electromotive force generated in the secondary coil in the off period exceeds the voltage of the sub capacitor, a current flows in the direction of charging the sub capacitor.

Abstract

Provided is an insulated switching power supply to which three-phase AC is input, wherein said insulated switching power supply efficiently improves a power factor with a simple configuration and performs power conversion. The insulated switching power supply has: input ends R, S, T; positive and negative electrode output ends P, N; three transformers Tr, Ts, Tt having respective primary coils connected to the respective input ends; three switching elements Qr, Qs, Qt for bringing the respective current paths between another ends of the respective primary coils of the three transformers and an input side reference voltage level end into a conductive state or a cut-off state; first, second, and third sub-capacitors C1, C2, C3 connected between one ends of the respective secondary coils of the three transformers and the negative electrode output end; first, second, and third rectifying elements D1, D2, D3 respectively connected between the other ends of the respective secondary coils of the three transformers and the positive electrode output end; fouth, fifth, and sixth rectifying elements D4, D5, D6 respectively connected between the other ends of the respective secondary coils of the three transformers and the negative electrode output end; and a smoothing capacitor connected between the positive electrode output end and the negative electrode output end.

Description

三相交流用絶縁型スイッチング電源Three phase AC isolated switching power supply
　本発明は、三相交流を直流に変換する絶縁型スイッチング電源に関する。 The present invention relates to an isolated switching power supply that converts three-phase alternating current to direct current.
　従来、交流を直流に変換するスイッチング電源において、絶縁型コンバータが知られている。様々な方式が提示されているが、単相及び三相に限らず、概ね交流電圧を整流回路により整流し平滑コンデンサにより平滑化することによりＡＣ／ＤＣ変換した後にＤＣ／ＤＣコンバータが配置されている（特許文献１～７）。力率改善を行うために、力率改善装置（ＰＦＣ）とＤＣ／ＤＣコンバータを組み合わせた２段構成も知られている。特許文献６、７には、風力発電の交流発電機の三相交流出力に対して昇圧と力率改善を行う装置が記載されている。 2. Description of the Related Art In the prior art, an isolated converter is known as a switching power supply for converting alternating current into direct current. Various systems have been presented, but DC / DC converters are disposed after AC / DC conversion by rectifying the alternating current voltage with a rectifying circuit and smoothing with a smoothing capacitor, not limited to single phase and three phase. Patent documents 1 to 7). Also known is a two-stage configuration in which a power factor correction device (PFC) and a DC / DC converter are combined to perform power factor correction. Patent Documents 6 and 7 describe an apparatus for boosting and improving the power factor of a three-phase AC output of a wind power alternator.
特開平７－３１１５０号公報Japanese Patent Application Laid-Open No. 7-31150 特開平８－３３１８６０号公報JP-A-8-331860 特開２００２－１０６３２号公報Japanese Patent Application Laid-Open No. 2002-10632 特開２００５－２１８２２４号公報JP 2005-218224 A 特開２００７－３７２９７号公報JP 2007-37297 A 特開２０１３－１２８３７９号公報JP, 2013-128379, A 特開２０１４－２３２８６号公報JP, 2014-23286, A
　従来の力率改善機能を備えたスイッチング電源において、２段構成とする場合は回路が複雑になるという問題があった。また、フォワード方式のコンバータでは、通常、トランス以外に外付けのチョークコイルが必要であった。 In the conventional switching power supply having a power factor improvement function, there is a problem that the circuit becomes complicated in the case of the two-stage configuration. In addition, in the forward converter, an external choke coil is usually required in addition to the transformer.
　以上の問題点に鑑み本発明は、三相交流が入力される絶縁型スイッチング電源において、簡易な構成により効率的な力率改善と電力変換を行うことを目的とする。 In view of the above problems, the present invention has an object of efficiently performing power factor improvement and power conversion with a simple configuration in an insulating switching power supply to which a three-phase alternating current is input.
　上記の目的を達成するべく、本発明は、以下の構成を提供する。なお、括弧内の符号は後述する図面中の符号であり、参考のために付するものである。 In order to achieve the above object, the present invention provides the following configuration. In addition, the code | symbol in parenthesis is a code | symbol in drawing mentioned later, and is attached for reference.
・　本発明のスイッチング電源の一態様は、
　（ａ）三相交流が入力される第１、第２及び第３入力端（R,S,T）と、
　（ｂ）正極出力端（P）及び負極出力端（N）と、
　（ｃ）各々が一次コイル（Lr1,Ls1,Lt1）と二次コイル（Lr2,Ls2,Lt2）を具備し各々の一次コイルの一端が前記第１、第２及び第３入力端（R,S,T）にそれぞれ接続された第１、第２及び第３トランス（Tr,Ts,Tt）と、
　（ｄ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の一次コイル（Lr1,Ls1,Lt1）の他端と入力側基準電位端（E）の間の各電流路を導通又は遮断するように１つの制御信号（Vg）によりオンオフ制御される第１、第２及び第３スイッチング素子（Qr,Qs,Qt）と、
　（ｅ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の二次コイル（Lr2,Ls2,Lt2）の一端と前記負極出力端（N）の間にそれぞれ接続された第１、第２及び第３サブコンデンサ（C1,C2,C3）と、
　（ｆ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の二次コイル（Lr2,Ls2,Lt2）の他端と前記正極出力端（P）の間にそれぞれ接続され、該二次コイルの他端から該正極出力端（P）へ流れる電流をそれぞれ導通させる第１、第２及び第３整流要素（D1,D2,D3）と、
　（ｇ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の二次コイル（Lr2,Ls2,Lt2）の他端と前記負極出力端（N）の間にそれぞれ接続され、該負極出力端（N）から該二次コイルの他端へ流れる電流をそれぞれ導通させる第４、第５及び第６整流要素（D4,D5,D6）と、
　（ｈ）前記正極出力端（P）と前記負極出力端（N）の間に接続された平滑コンデンサ（C4）と、を有することを特徴とする。 One aspect of the switching power supply of the present invention is
(A) first, second and third input terminals (R, S, T) to which three-phase alternating current is input;
(B) positive electrode output end (P) and negative electrode output end (N),
(C) Each has a primary coil (Lr1, Ls1, Lt1) and a secondary coil (Lr2, Ls2, Lt2), and one end of each primary coil has the first, second and third input ends (R, S) , T) respectively connected to the first, second and third transformers (Tr, Ts, Tt),
(D) Each current path between the other end of the primary coil (Lr1, Ls1, Lt1) of each of the first, second and third transformers (Tr, Ts, Tt) and the input side reference potential end (E) First, second and third switching elements (Qr, Qs, Qt) which are on / off controlled by one control signal (Vg) to conduct or interrupt
(E) One end of the secondary coil (Lr2, Ls2, Lt2) of each of the first, second and third transformers (Tr, Ts, Tt) and the negative output end (N) are connected to each other First, second and third sub capacitors (C1, C2, C3),
(F) connected between the other end of the secondary coil (Lr2, Ls2, Lt2) of each of the first, second and third transformers (Tr, Ts, Tt) and the positive electrode output end (P) First, second and third rectifying elements (D1, D2, D3) for respectively conducting a current flowing from the other end of the secondary coil to the positive electrode output end (P);
(G) connected between the other end of the secondary coil (Lr2, Ls2, Lt2) of each of the first, second and third transformers (Tr, Ts, Tt) and the negative output end (N) Fourth, fifth and sixth rectifying elements (D4, D5, D6) for respectively conducting the current flowing from the negative electrode output end (N) to the other end of the secondary coil;
(H) A smoothing capacitor (C4) connected between the positive electrode output end (P) and the negative electrode output end (N) is characterized.
　本発明により、三相交流を入力され力率改善と電力変換を行う絶縁型スイッチング電源において、簡易な構成とすることができ、トランスの効率を向上させることができる。 According to the present invention, in an isolated switching power supply that receives a three-phase alternating current and performs power factor improvement and power conversion, the configuration can be simplified and the efficiency of the transformer can be improved.
図１は、本発明のスイッチング電源の実施形態の回路構成例を概略的に示した図である。FIG. 1 is a view schematically showing an example of the circuit configuration of the embodiment of the switching power supply according to the present invention. 図２（ａ）（ｂ）は、入力される三相交流とスイッチング動作による力率改善作用を説明するための図である。FIGS. 2 (a) and 2 (b) are diagrams for explaining the power factor improvement action by the input three-phase alternating current and the switching operation. 図３は、図１に示した回路構成のＴモードにおけるオン期間の電流の流れを概略的に示す図である。FIG. 3 is a diagram schematically showing the flow of current during the on period in the T mode of the circuit configuration shown in FIG. 図４は、図１に示した回路構成の二次側におけるオン期間の電位関係を模式的に示した図である。FIG. 4 is a diagram schematically showing the potential relationship of the on period on the secondary side of the circuit configuration shown in FIG. 図５は、図１に示した回路構成のＴモードにおけるオフ期間の電流の流れを概略的に示す図である。FIG. 5 is a diagram schematically showing the flow of current during the off period in the T mode of the circuit configuration shown in FIG. 図６は、図１に示した回路構成の二次側におけるオフ期間の電位関係を模式的に示した図である。FIG. 6 is a diagram schematically showing the potential relationship of the off period on the secondary side of the circuit configuration shown in FIG.
　以下、実施例を示した図面を参照しつつ、本発明によるスイッチング電源の実施形態について説明する。 Hereinafter, an embodiment of a switching power supply according to the present invention will be described with reference to the drawings showing the embodiments.
（１）回路構成
　図１は、本発明の絶縁型スイッチング電源の実施形態の回路構成の一例を概略的に示した図である。 (1) Circuit Configuration FIG. 1 is a view schematically showing an example of a circuit configuration of an embodiment of the isolated switching power supply of the present invention.
　本発明のスイッチング電源は、交流発電機により出力される三相交流電力を入力とし、負荷に対して直流電力を出力する電力変換装置である。例えば風力発電では、風車が回転し交流発電機の軸が回転すると、交流発電機においてＹ結線された三相のステータコイルから三相交流電力が出力される。 The switching power supply of the present invention is a power conversion device that receives three-phase AC power output from an AC generator as input and outputs DC power to a load. For example, in wind power generation, when the wind turbine rotates and the shaft of the AC generator rotates, three-phase AC power is output from a Y-connected three-phase stator coil in the AC generator.
　本発明のスイッチング電源は、電力変換装置であるとともに、力率改善装置としての機能も兼ね備えている。力率改善装置は、入力電流の波形を入力電圧と同じ正弦波の波形としかつ位相を一致させて力率を１とすることを目的とする。 The switching power supply of the present invention is not only a power conversion device but also has a function as a power factor correction device. The power factor correction device aims to make the power factor equal to 1 by making the waveform of the input current the same as that of the input voltage and making the phase match.
　本発明のスイッチング電源は、入力側と出力側を電気的に絶縁する絶縁型である。このために、各相に対応する３つのトランスＴr、Ｔs、Ｔtを設けている。３つのトランスＴr、Ｔs、Ｔtはそれぞれ１つの一次コイルと１つの二次コイルを具備する。３つのトランスＴr、Ｔs、Ｔtは電気磁気特性が等しいものを用いることが好適であり、三相リアクトルを用いることが好適である。符号Ｌr1、Ｌs1、Ｌt1は各トランスの一次コイルを示し、符号Ｌr2、Ｌs2、Ｌt2は各トランスの二次コイルを示す。 The switching power supply of the present invention is an insulating type that electrically isolates the input side from the output side. For this purpose, three transformers Tr, Ts and Tt corresponding to each phase are provided. Each of the three transformers Tr, Ts, Tt comprises one primary coil and one secondary coil. It is preferable to use three transformers Tr, Ts, and Tt having the same electromagnetic characteristics, and it is preferable to use a three-phase reactor. The symbols Lr1, Ls1 and Lt1 indicate primary coils of the respective transformers, and the symbols Lr2, Ls2 and Lt2 indicate secondary coils of the respective transformers.
　各コイルの巻き始端を黒丸で示している。本明細書でコイルについて「一端」と「他端」という場合は、「巻き始端」と「巻き終端」の組合せを意味する場合と、「巻き終端」と「巻き始端」の組合せを意味する場合のいずれも含むものとする。 The winding start end of each coil is shown by a black circle. In the present specification, when a coil is referred to as "one end" and "the other end", it means a combination of "winding start end" and "winding end" and a combination of "winding end" and "winding start". Shall be included.
　入力側であるトランスの一次コイルＬr1、Ｌs1、Ｌt1の一端（本例では巻き始端）は、三相交流電圧が入力される３つの端子である第１入力端Ｒ、第２入力端Ｓ及び第３入力端Ｔにそれぞれ接続されている。本明細書では、三相交流の各相をＲ相、Ｓ相、Ｔ相と称する。符号Ｅは、入力側基準電位端を示す。 One end (in this example, the winding start end) of the primary coils Lr1, Ls1 and Lt1 of the transformer on the input side has three terminals to which a three-phase AC voltage is input: a first input end R, a second input end S and a first The three input terminals T are respectively connected. In the present specification, each phase of the three-phase alternating current is referred to as an R phase, an S phase, and a T phase. The symbol E indicates the input side reference potential end.
　トランスの二次側には、直流電圧が出力される２つの端子である正極出力端Ｐと負極出力端Ｎが設けられている。負極出力端Ｎは、二次側基準電位端である。正極出力端Ｐと負極出力端Ｎの間に接続された負荷（図示せず）に出力電圧が印加され、出力電流が流れる。 On the secondary side of the transformer, a positive electrode output terminal P and a negative electrode output terminal N, which are two terminals to which a DC voltage is output, are provided. The negative output end N is a secondary side reference potential end. An output voltage is applied to a load (not shown) connected between the positive electrode output terminal P and the negative electrode output terminal N, and an output current flows.
　各トランスの一次コイルＬr1、Ｌs1、Ｌt1の他端（本例では巻き終端）には、３つのスイッチング素子Ｑr、Ｑs、Ｑtの各々の一端が接続されている。各スイッチング素子Ｑr、Ｑs、Ｑtの他端は、入力側基準電位端Ｅに接続されている。各スイッチング素子Ｑr、Ｑs、Ｑtは制御端をそれぞれ具備し、各制御端は、一次コイルＬr1、Ｌs1、Ｌt1の他端と入力側基準電位端Ｅの間の電流路を導通又は遮断するようにそれぞれオンオフ制御される。 One end of each of the three switching elements Qr, Qs, Qt is connected to the other end (in this example, the winding end) of the primary coil Lr1, Ls1, Lt1 of each transformer. The other ends of the switching elements Qr, Qs, Qt are connected to the input side reference potential end E. Each switching element Qr, Qs, Qt has a control end, and each control end conducts or cuts off the current path between the other end of the primary coils Lr1, Ls1, Lt1 and the input side reference potential end E. Each is on / off controlled.
　３つのスイッチング素子Ｑr、Ｑs、Ｑtの各制御端は、共通する１つの制御信号Ｖｇにより制御される。制御信号Ｖｇは、例えば所定の周波数及びデューティ比のパルス波形をもつＰＷＭ信号である。すなわち、３つのスイッチング素子Ｑr、Ｑs、Ｑtは、常に同時にオンオフするように制御される。図示の例では、スイッチング素子Ｑr、Ｑs、Ｑtがｎチャネル形ＭＯＳＦＥＴ（以下「ＦＥＴＱr」、「ＦＥＴＱs」、「ＦＥＴＱt」と称する）であり、一端がドレイン、他端がソース、制御端がゲートである。この場合、制御信号Ｖｇは電圧信号である。 The control ends of the three switching elements Qr, Qs, Qt are controlled by one common control signal Vg. The control signal Vg is, for example, a PWM signal having a pulse waveform of a predetermined frequency and a duty ratio. That is, the three switching elements Qr, Qs, Qt are controlled to always be turned on and off at the same time. In the illustrated example, the switching elements Qr, Qs, Qt are n-channel MOSFETs (hereinafter referred to as "FETQr", "FETQs", "FETQt"), one end is a drain, the other end is a source, and the control end is a gate. is there. In this case, the control signal Vg is a voltage signal.
　なお、ＦＥＴ以外のスイッチング素子Ｑr、Ｑs、Ｑt、例えばＩＧＢＴやバイポーラトランジスタの場合は、電流の還流経路となるダイオード等の整流要素をそれぞれ逆並列接続する必要がある。 In the case of switching elements Qr, Qs, Qt other than FETs, for example, in the case of IGBTs or bipolar transistors, rectifying elements such as diodes serving as current return paths need to be connected in reverse parallel.
　さらに、各トランスの二次コイルＬr2、Ｌs2、Ｌt2の一端（本例では巻き始端）と二次側基準電位端である負極出力端Ｎの間には、第１、第２及び第３のコンデンサ（以下「サブコンデンサ」と称する）Ｃ１、Ｃ２、Ｃ３がそれぞれ接続されている。また、正極出力端Ｐと負極出力端Ｎの間には、平滑コンデンサＣ４が接続されている。 Furthermore, first, second and third capacitors are disposed between one end (in this example, the winding start end) of the secondary coils Lr2, Ls2 and Lt2 of each transformer and the negative output end N which is the secondary side reference potential end. C1, C2, and C3 (hereinafter referred to as "sub capacitors") are connected to one another. In addition, a smoothing capacitor C4 is connected between the positive electrode output terminal P and the negative electrode output terminal N.
　各トランスの二次コイルＬr2、Ｌs2、Ｌt2の他端（本例では巻き終端）と正極出力端Ｐの間には、整流要素の一例である第１、第２及び第３のダイオードＤ１、Ｄ２、Ｄ３がそれぞれ接続されている。ダイオードＤ１、Ｄ２、Ｄ３の各アノードがそれぞれ二次コイルＬr2、Ｌs2、Ｌt2の各他端に接続され、各カソードが正極出力端Ｐに接続される。各ダイオードＤ１、Ｄ２、Ｄ３は、順バイアスのときに各トランスの二次コイルＬr2、Ｌs2、Ｌt2の他端から正極出力端Ｐへそれぞれ流れる電流を導通させ、逆バイアスのときはそれぞれ電流を遮断する。 Between the other end (in this example, the winding end) of the secondary coils Lr2, Ls2 and Lt2 of each transformer and the positive electrode output end P, first, second and third diodes D1 and D2 which are an example of rectifying elements , D3 are connected respectively. The anodes of the diodes D1, D2 and D3 are connected to the other ends of the secondary coils Lr2, Ls2 and Lt2, respectively, and the cathodes are connected to the positive electrode output terminal P. Each diode D1, D2, D3 conducts the current flowing from the other end of the secondary coil Lr2, Ls2, Lt2 of each transformer to the positive output terminal P when forward biased, and shuts off the current when reverse biased Do.
　ダイオードＤ１、Ｄ２、Ｄ３は、順方向電圧降下が小さくかつ高速動作を行うものが好適である。 The diodes D1, D2 and D3 preferably have small forward voltage drop and operate at high speed.
　さらに、各トランスの二次コイルＬr2、Ｌs2、Ｌt2の他端と負極出力端Ｎの間には、整流要素の一例である第４、第５及び第６のダイオードＤ４、Ｄ５、Ｄ６がそれぞれ接続されている。ダイオードＤ４、Ｄ５、Ｄ６の各カソードが二次コイルＬr2、Ｌs2、Ｌt2の各他端に接続され、各アノードが負極出力端Ｎに接続される。各ダイオードＤ４、Ｄ５、Ｄ６は、順バイアスのときに負極出力端Ｎから各トランスの二次コイルＬr2、Ｌs2、Ｌt2の他端へそれぞれ流れる電流を導通させ、逆バイアスのときはそれぞれ遮断する。 Furthermore, fourth, fifth and sixth diodes D4, D5 and D6, which are an example of a rectifying element, are connected between the other end of the secondary coils Lr2, Ls2 and Lt2 of each transformer and the negative output end N, respectively. It is done. The cathodes of the diodes D4, D5, D6 are connected to the other ends of the secondary coils Lr2, Ls2, Lt2, respectively, and the anodes are connected to the negative output terminal N. Each of the diodes D4, D5, D6 conducts the current flowing from the negative electrode output end N to the other end of the secondary coil Lr2, Ls2, Lt2 of each transformer when forward biased, and blocks the current when reverse biased.
　さらに、図示しないが、制御信号Ｖｇを発生する制御部を有する。例えば入力電圧と直流出力電圧の大きさを検出し、検出された入力電圧と出力電圧に基づいて、制御信号Ｖｇのデューティ比を決定し、それに基づいて制御信号Ｖｇを生成する。制御部の主要部として、ＰＷＭＩＣを用いることが好適である。 Furthermore, although not shown, a control unit that generates a control signal Vg is included. For example, the magnitudes of the input voltage and the DC output voltage are detected, the duty ratio of the control signal Vg is determined based on the detected input voltage and output voltage, and the control signal Vg is generated based thereon. It is preferable to use PWMIC as a main part of the control unit.
　ＰＷＭＩＣは、例えば、決定された１つのデューティ比に対応する一定電圧の直流信号と、一定の周波数をもつ搬送三角波信号とを比較器に入力することにより、一定のデューティ比をもつパルス状の制御信号Ｖｇを出力する。本発明では、このような制御信号Ｖｇを「一定のデューティ比をもつ」制御信号と称している。 The PWMIC controls, for example, a pulse-like control having a constant duty ratio by inputting a DC signal of a constant voltage corresponding to one determined duty ratio and a carrier triangular wave signal having a constant frequency to the comparator. The signal Vg is output. In the present invention, such a control signal Vg is referred to as a "constant duty ratio" control signal.
（２）動作説明
　図２～図６を参照して、図１に示した回路構成の動作を説明する。なお、本回路の始動時及び停止時の過渡的動作は例外とし、本回路が定常状態にある場合の動作について説明する。 (2) Description of Operation The operation of the circuit configuration shown in FIG. 1 will be described with reference to FIGS. The transient operation at the start and stop of the circuit is an exception, and the operation when the circuit is in the steady state will be described.
（２－１）入力三相交流及び力率改善作用
　先ず、図２（ａ）（ｂ）を参照して入力三相交流に対するスイッチング動作による力率改善作用を説明する。 (2-1) Input Three-Phase AC and Power Factor Improving Function First, the power factor improving action by the switching operation for the input three-phase AC will be described with reference to FIGS. 2 (a) and 2 (b).
　図２（ａ）は、入力三相交流のＲ相、Ｓ相、Ｔ相の電圧波形を示している。最高電位となる相と最低電位となる相は、それぞれ位相１２０°毎に順次入れ替わっている。三相交流の周波数は、例えば風力発電の交流発電機の場合、数Ｈｚ～１００Ｈｚ程度である。一方、スイッチング周波数すなわち図１における制御信号Ｖｇの周波数は、数ｋＨｚ～数百ｋＨｚであり、三相交流の周波数に比べて十分に高い。 FIG. 2A shows voltage waveforms of R phase, S phase, and T phase of the input three-phase alternating current. The phase having the highest potential and the phase having the lowest potential are sequentially switched at every phase of 120 °. The frequency of the three-phase alternating current is, for example, about several Hz to 100 Hz in the case of an alternator for wind power generation. On the other hand, the switching frequency, that is, the frequency of the control signal Vg in FIG. 1 is several kHz to several hundreds kHz, which is sufficiently higher than the frequency of the three-phase alternating current.
　一例として、Ｔ相が最低電位となる期間（「Ｔモード」と称する）について説明する。なお、Ｒ相が最低電位となる期間（「Ｒモード」と称する）及びＳ相が最低電位となる期間（「Ｓモード」と称する）については、同様であるので説明を省略する。 As an example, a period in which the T phase is at the lowest potential (referred to as “T mode”) will be described. The same applies to the period in which the R phase is at the lowest potential (referred to as “R mode”) and the period in which the S phase is at the lowest potential (referred to as “S mode”).
　Ｔモードでは、その期間の前半にＲ相が最高電位となり、後半にＳ相が最高電位となる。図１においてＦＥＴＱr、Ｑs、Ｑtのオン期間には、正電位の相と負電位の相の相間電圧により入力電流が流れ、オフ期間には電流は流れない。 In the T mode, the R phase has the highest potential in the first half of the period, and the S phase has the highest potential in the second half. In FIG. 1, in the on period of the FETs Qr, Qs, and Qt, an input current flows due to the voltage between the positive potential phase and the negative potential phase, and no current flows in the off period.
　以下の動作説明では、例として、オン期間に最高電位のＲ相又はＳ相から最低電位のＴ相へと、ＲＴ相間電圧又はＳＴ相間電圧により入力電流が流れる場合について説明する（他の場合についても動作は同様であるので説明を省略する）。 In the following description of the operation, as an example, the case where the input current flows due to the RT phase voltage or the ST phase voltage from the R phase or S phase of the highest potential to the T phase of the lowest potential in the on period will be described Since the operation is the same, the description will be omitted).
　ここでは、例えばＲ相とＴ相の間の相間電圧を「ＲＴ相間電圧」等と称し「ｖrt」と表す。また、例えばＲＴ相間電圧ｖrtにより流れる入力電流を「ｉrt」と表す。 Here, for example, an inter-phase voltage between the R phase and the T phase is referred to as an “RT inter-phase voltage” or the like and denoted as “vrt”. Further, for example, the input current flowing by the RT inter-phase voltage vrt is represented as "irt".
　図２（ｂ）を参照して力率改善作用について説明する。図２（ｂ）は、一例として、図２（ａ）の時間軸ｔ上のＡ点におけるＰＷＭ制御信号の波形と、ＲＴ相間電圧ｖrtと、第１入力端Ｒと第３入力端Ｔの間に流れるオン電流ｉrtとを模式的に示している。スイッチング周波数は、三相交流の周波数に比べて十分に高いので、１つのオン期間のＲＴ相間電圧ｖrtはパルス状の一定電圧と見なすことができる。従って、オン電流ｉrtの始点の値は、ＲＴ相間電圧ｖrtと、第１入力端Ｒと第３入力端Ｔの間の電流路上にあるインダクタンスＬによって、ｉrt＝ｖrt／Ｌω（ωはスイッチング周波数）で決まる。電流ｉrtは、オン期間にリニアに上昇する。オフ期間には、電流ｉrtは零となる。 The power factor improvement action will be described with reference to FIG. 2 (b). FIG. 2B shows, as an example, the waveform of the PWM control signal at point A on the time axis t in FIG. 2A, the voltage between rt phases vrt, and between the first input end R and the third input end T. The on current irt flowing through the is schematically shown. Since the switching frequency is sufficiently high compared to the frequency of the three-phase alternating current, the RT interphase voltage vrt in one on period can be regarded as a pulse-like constant voltage. Therefore, the value of the start point of the on current irt is irt = vrt / Lω (ω is a switching frequency) by the RT phase voltage vrt and the inductance L on the current path between the first input end R and the third input end T. It depends on The current irt rises linearly during the on period. In the off period, the current irt is zero.
　電流路上のインダクタンスＬ及びスイッチング周波数ωは定数であるので、オン期間の電流ｉrtの始点の値は、オン期間の始点におけるＲＴ相間電圧ｖrtの瞬時値により決まる。ＲＴ相間電圧ｖrtの瞬時値は、正弦波の軌跡上に点在するので、オン期間に一次コイルに流れる電流ｉrtもまた、正弦波の軌跡を描くことになる。このことは、入力電流が入力電圧と同じ位相の正弦波であることを意味する。これにより、一次側における力率改善が実現される。 Since the inductance L on the current path and the switching frequency ω are constants, the value of the start point of the current irt in the on period is determined by the instantaneous value of the RT inter-phase voltage vrt at the start point of the on period. Since the instantaneous value of the RT inter-phase voltage vrt is scattered on the locus of the sine wave, the current irt flowing through the primary coil during the on period also draws the locus of the sine wave. This means that the input current is a sine wave in phase with the input voltage. Thereby, the power factor improvement on the primary side is realized.
　本回路では、三相交流の相間電圧が印加されるインダクタンスを含む電流路を、一定の周波数とデューティ比をもつＰＷＭ制御信号を用いて導通・遮断することにより、入力電圧と位相の一致した正弦波の入力電流を得ることができる。 In this circuit, a current path including an inductance to which a three-phase AC interphase voltage is applied is turned on / off by using a PWM control signal having a constant frequency and a duty ratio, whereby a sine whose phase matches the input voltage The input current of the wave can be obtained.
（２－２）オン期間における一次側及び二次側の動作の詳細
　図３は、図１に示した回路構成において、Ｔモードにおけるオン期間の電流の流れ（矢印付き点線）を概略的に示している。 (2-2) Details of Operation of Primary Side and Secondary Side in On Period FIG. 3 schematically shows a current flow (dotted line with an arrow) in the on period in T mode in the circuit configuration shown in FIG. ing.
［オン期間：一次側］
　トランス一次側では、オン期間に制御信号Ｖｇがオン電圧になると、ＦＥＴＱr、ＦＥＴＱs、ＦＥＴＱtがいずれもオンとなり電流路が導通する。 [On period: Primary side]
On the primary side of the transformer, when the control signal Vg becomes the on voltage during the on period, all of the FETQr, the FETQs, and the FETQt are turned on, and the current path is conducted.
　トランスＴrの一次コイルにはＲＴ相間電圧ｖrtにより、入力電流ｉrtが以下の経路で流れる。
　・入力電流ｉrt：第１入力端Ｒ→トランスＴr一次コイル→ＦＥＴＱr→ＦＥＴＱt→トランスＴt一次コイル→第３入力端Ｔ An input current irt flows in the following path in the primary coil of the transformer Tr due to the RT phase voltage vrt.
· Input current irt: first input end R → transformer Tr primary coil → FET Qr → FET Qt → transformer Tt primary coil → third input end T
　トランスＴsの一次コイルにはＳＴ相間電圧ｖstにより、入力電流ｉstが以下の経路で流れる。
　・入力電流ｉst：第２入力端Ｓ→トランスＴs一次コイル→ＦＥＴＱs→ＦＥＴＱt→トランスＴt一次コイル→第３入力端Ｔ The input current ist flows through the primary coil of the transformer Ts in the following path due to the ST phase voltage vst.
· Input current ist: second input end S → transformer Ts primary coil → FET Qs → FET Qt → transformer Tt primary coil → third input end T
　ここで、トランスＴｔの一次コイルから第３入力端Ｔへと流れる電流のように、入力側へ戻る電流を、以下「還流」と称する。 Here, the current returning to the input side, such as the current flowing from the primary coil of the transformer Tt to the third input terminal T, is hereinafter referred to as “reflux”.
［オン期間：二次側］
　図３中では、説明の便宜上、トランスＴr、Ｔs、Ｔtの二次コイル他端（本例では巻き終端）をそれぞれａ点、ｂ点、ｃ点とし、トランスＴr、Ｔs、Ｔtの二次コイル一端（本例では巻き始端）をｄ点、ｅ点、ｆ点とする。さらに、正極出力端Ｐをｈ点とし、負極出力端Ｎをｇ点とする。ｈ点は、平滑コンデンサＣ４の一端でもある。ｇ点は、サブコンデンサＣ１、Ｃ２、Ｃ３及び平滑コンデンサＣ４の共通端でもあり、二次側基準電位端である。 [On period: Secondary side]
In FIG. 3, for convenience of explanation, the other ends (in this example, the winding ends) of the secondary coils of the transformer Tr, Ts and Tt are respectively a point, b and c points, and the secondary coil of the transformer Tr, Ts and Tt Let one end (in this example, the winding start end) be point d, point e, and point f. Furthermore, the positive electrode output end P is a point h, and the negative electrode output end N is a point g. The point h is also one end of the smoothing capacitor C4. The point g is also a common end of the sub capacitors C1, C2, C3 and the smoothing capacitor C4, and is a secondary side reference potential end.
　図４は、オン期間におけるトランス二次側のａ点～ｈ点の電位関係を模式的に示した図である。図４も参照しつつ、オン期間のトランス二次側の動作を説明する。 FIG. 4 is a diagram schematically showing the potential relationship between the point a to h on the transformer secondary side in the on period. The operation of the transformer secondary side in the on period will be described with reference also to FIG.
　定常状態では、サブコンデンサＣ１、Ｃ２、Ｃ３及び平滑コンデンサＣ４は、それぞれ所定の両端電圧ＶC1、ＶC2、ＶC3、ＶC4で充電されている。 In the steady state, the sub-capacitors C1, C2, C3 and the smoothing capacitor C4 are charged with the voltages Vc1, Vc2, Vc3, VC4 at both ends respectively.
　トランスＴrの一次コイルに入力電流ｉrtが流れることにより、二次コイルに起電力Ｖrが生じる。起電力Ｖrは、ｄ点側が高電位、ａ点側が低電位の向きである。ダイオードＤ１は、この起電力Ｖrに対して逆バイアスとなるため電流は流れない。一方、ダイオードＤ４は順バイアスとなり導通する。 When the input current irt flows in the primary coil of the transformer Tr, an electromotive force Vr is generated in the secondary coil. In the electromotive force Vr, the d point side is a high potential, and the a point side is a low potential direction. Since the diode D1 is reverse biased with respect to the electromotive force Vr, no current flows. On the other hand, diode D4 becomes forward biased and becomes conductive.
　ここで、図４に示すオン期間の電位関係図を参照する。トランスＴrの二次コイルａ点は、ダイオードＤ４が導通するので、二次側基準電位端ｇ点と同電位となる。トランスＴrの起電力ＶrがサブコンデンサＣ１の両端電圧ＶC1を超えると、サブコンデンサＣ１を充電する方向にオン期間の電流ｉronが以下の経路で流れる。
　・電流ｉron：トランスＴr二次コイルｄ点→サブコンデンサＣ１→ダイオードＤ４→トランスＴｒ二次コイルａ点 Here, a potential relationship diagram of the on period shown in FIG. 4 is referred to. The secondary coil a point of the transformer Tr is at the same potential as the secondary side reference potential end point g because the diode D4 conducts. When the electromotive force Vr of the transformer Tr exceeds the voltage VC1 across the sub capacitor C1, the current iron of the on period flows in the following path in the direction of charging the sub capacitor C1.
Current iron: transformer Tr secondary coil point d sub capacitor C1 diode D4 transformer Tr secondary coil point a
　また、トランスＴsの一次コイルに入力電流ｉstが流れることにより、二次コイルに起電力Ｖsが生じる。起電力Ｖsは、ｅ点側が高電位、ｂ点側が低電位の向きである。ダイオードＤ２は、この起電力Ｖsに対して逆バイアスとなるため電流は流れない。一方、ダイオードＤ５は順バイアスとなり導通する。 Further, when the input current ist flows through the primary coil of the transformer Ts, an electromotive force Vs is generated in the secondary coil. The electromotive force Vs is directed to a high potential at point e and a low potential at point b. Since the diode D2 is reverse biased with respect to the electromotive force Vs, no current flows. On the other hand, diode D5 is forward biased and turned on.
　ここで、図４に示すオン期間の電位関係図を参照する。トランスＴsの二次コイルｂ点は、ダイオードＤ５が導通するので、二次側基準電位端ｇ点と同電位となる。トランスＴsの起電力ＶsがサブコンデンサＣ２の両端電圧ＶC2を超えると、サブコンデンサＣ２を充電する方向にオン期間の電流ｉsonが以下の経路で流れる。
　・電流ｉson：トランスＴs二次コイルｅ点→サブコンデンサＣ２→ダイオードＤ５→トランスＴs二次コイルｂ点 Here, a potential relationship diagram of the on period shown in FIG. 4 is referred to. The secondary coil b of the transformer Ts has the same potential as the point g on the secondary side reference potential end because the diode D5 conducts. When the electromotive force Vs of the transformer Ts exceeds the voltage VC2 across the sub capacitor C2, the current ison of the on period flows in the following path in the direction of charging the sub capacitor C2.
Current ison: transformer Ts secondary coil point e → sub capacitor C 2 → diode D 5 → transformer Ts secondary coil point b
　また、トランスＴtは、その一次コイルに還流が流れることにより、二次コイルに起電力Ｖtが生じる。起電力Ｖtは、ｆ点側が低電位、ｃ点側が高電位の向きであり、トランスＴr及びＴsとは逆向きである。ダイオードＤ６は、この起電力Ｖtに対して逆バイアスとなるため電流は流れない。 In addition, in the transformer Tt, an electromotive force Vt is generated in the secondary coil when reflux flows in the primary coil. The electromotive force Vt has a low potential at the point f side and a high potential at the point c side, and is in the opposite direction to the transformer Tr and Ts. Since the diode D6 is reverse biased with respect to the electromotive force Vt, no current flows.
　ここで、図４に示すオン期間の電位関係図を参照する。起電力ＶtによりトランスＴtの二次コイルｃ点電位がｆ点電位に対して上昇し、平滑コンデンサＣ４の一端（第１出力端Ｐ）であるｈ点電位を超えると、ダイオードＤ３が順バイアスとなり、電流ｉtonが以下の経路で流れる。
　・電流ｉton：トランスＴt二次コイルｃ点→ダイオードＤ３→ｈ点→負荷→ｇ点→サブコンデンサＣ３→トランスＴt二次コイルｆ点 Here, a potential relationship diagram of the on period shown in FIG. 4 is referred to. When the electromotive force Vt causes the secondary coil c potential of the transformer Tt to rise relative to the f potential, and exceeds the h point potential which is one end (first output end P) of the smoothing capacitor C4, the diode D3 becomes forward biased , The current iton flows in the following path.
· Current iton: transformer Tt secondary coil c point → diode D3 → h point → load → g point → sub capacitor C3 → transformer Tt secondary coil f point
　電流ｉtonは、負荷へ供給される。従って電流ｉtonは、フォワード方式におけるフォワード電流に相当する。なお、負荷への供給電流は、平滑コンデンサＣ４からの放電電流も合流される。電流ｉtonによりサブコンデンサＣ３は放電するので、ｆ点電位はその分だけ低下し、サブコンデンサＣ３の両端電圧ＶC3は小さくなる。 The current iton is supplied to the load. Therefore, the current iton corresponds to the forward current in the forward system. The supply current to the load is also merged with the discharge current from the smoothing capacitor C4. Since the sub capacitor C3 is discharged by the current iton, the potential at the point f decreases by that amount, and the voltage VC3 across the sub capacitor C3 decreases.
　図４のオン期間の電位関係から判るように、ｉtonが流れるときのｃ点（ｈ点）電位は、ｇ点電位に対して、サブコンデンサＣ３の両端電圧ＶC3とトランスＴtの起電力Ｖtとを加算したものとなっている。 As can be seen from the potential relationship in the on period in FIG. 4, the potential at point c (point h) when it flows flows the voltage VC3 across the sub capacitor C3 and the electromotive force Vt of the transformer Tt with respect to the potential at point g. It has become an addition.
　なお、トランスＴｔの起電力Ｖｔは、一次コイルの還流の大きさにより決まる。トランスＴｔの起電力Ｖtが小さいときは、ｃ点電位がｈ点電位を超えない（ｃ’点電位を参照）。この場合は、電流ｉtonは流れない。 The electromotive force Vt of the transformer Tt is determined by the magnitude of the reflux of the primary coil. When the electromotive force Vt of the transformer Tt is small, the potential at the point c does not exceed the potential at the point h (see the potential at the point c '). In this case, the current iton does not flow.
　本回路のオン期間の動作をまとめると、次の通りである。一次コイルに入力電流が流れるトランスにおいては、二次コイルに発生した起電力がサブコンデンサの電圧を超えると、サブコンデンサを充電する方向に電流が流れる。一方、一次コイルに還流が流れるトランスにおいては、二次コイルに発生する起電力がサブコンデンサの電圧に加算される。加算された電圧が平滑コンデンサの電圧を超えると負荷へ電流が流れる。 The operation during the on period of this circuit is summarized as follows. In a transformer in which an input current flows in the primary coil, when the electromotive force generated in the secondary coil exceeds the voltage of the sub capacitor, a current flows in the direction of charging the sub capacitor. On the other hand, in the transformer in which the return flow flows to the primary coil, the electromotive force generated in the secondary coil is added to the voltage of the sub capacitor. When the added voltage exceeds the voltage of the smoothing capacitor, current flows to the load.
　通常のフォワード方式では、オン期間に外付けチョークコイルに磁気エネルギーが蓄積され、通常のフライバック方式では、オン期間にトランスに磁気エネルギーが蓄積される。これに対し、本回路では、オン期間に二次側に流れる電流ｉron、ｉsonにより、サブコンデンサＣ１、Ｃ２にそれぞれエネルギーが蓄積される。さらに、オン期間に二次側に流れる電流ｉtonにより、エネルギーが負荷へ供給される。この結果、本回路では、外付けチョークコイルが不要である。 In the normal forward system, magnetic energy is stored in the external choke coil in the on period, and in the normal flyback system, the magnetic energy is stored in the transformer in the on period. On the other hand, in the present circuit, energy is stored in the sub capacitors C1 and C2 by the currents iron and is respectively flowing to the secondary side during the on period. Furthermore, energy is supplied to the load by the current iton flowing to the secondary side during the on period. As a result, the circuit does not require an external choke coil.
（２－３）オフ期間における一次側及び二次側の動作の詳細
　図５は、図１の回路構成において、Ｔモードにおけるオフ期間の電流の流れ(矢印付き点線)を概略的に示す図である。 (2-3) Details of Operation of Primary Side and Secondary Side in Off Period FIG. 5 schematically shows the current flow (dotted line with arrow) in the off period in T mode in the circuit configuration of FIG. is there.
［オフ期間：一次側］
　トランス一次側では、制御信号Ｖｇがオフになると、ＦＥＴＱr、ＦＥＴＱs、ＦＥＴＱtがいずれもオフとなりスイッチが開く。各トランスの一次コイルの各電流路は遮断され、電流が零となる。これによりトランスＴr、Ｔs、Ｔtの一次コイル及び二次コイルにそれぞれ逆起電力が生じる。 [Off period: Primary side]
On the primary side of the transformer, when the control signal Vg is turned off, the FETQr, the FETQs, and the FETQt are all turned off and the switch is opened. Each current path of the primary coil of each transformer is cut off and the current is zero. Thereby, back electromotive force is generated in the primary coil and the secondary coil of the transformer Tr, Ts, Tt respectively.
［オフ期間：二次側］
　図６は、オフ期間におけるトランス二次側のａ点～ｈ点の電位関係を模式的に示した図である。図６も参照しつつ、オフ期間の二次側の動作を説明する。 [Off period: Secondary side]
FIG. 6 is a diagram schematically showing the potential relationship between the point a to h on the transformer secondary side in the off period. The operation on the secondary side of the off period will be described with reference also to FIG.
　トランスＴrの二次コイルに生じた逆起電力Ｖrは、ｄ点側が低電位、ａ点側が高電位の向きである。ダイオードＤ４は、この逆起電力Ｖrに対して逆バイアスとなるため電流は流れない。 The back electromotive force Vr generated in the secondary coil of the transformer Tr is directed to a low potential on the point d side and a high potential on the a point side. Since the diode D4 is reverse biased with respect to the back electromotive force Vr, no current flows.
　ここで、図６に示すオフ期間の電位関係図を参照する。逆起電力ＶrによりトランスＴrの二次コイルａ点電位がｄ点電位に対して上昇する。ａ点電位が平滑コンデンサＣ４の一端（第１出力端Ｐ）であるｈ点電位を超えると、ダイオードＤ１が順バイアスとなり電流ｉroffが以下の経路で流れる。
　・電流ｉroff：トランスＴr二次コイルａ点→ダイオードＤ１→ｈ点→負荷（又は平滑コンデンサＣ４）→ｇ点→サブコンデンサＣ１→トランスＴr二次コイルｄ点 Here, a potential relationship diagram of the off period shown in FIG. 6 is referred to. The back electromotive force Vr causes the potential at the secondary coil a of the transformer Tr to rise with respect to the potential at the point d. When the potential at the point a exceeds the potential at the point h, which is one end (first output end P) of the smoothing capacitor C4, the diode D1 becomes forward biased and the current iroff flows in the following path.
· Current iroff: transformer Tr secondary coil point a → diode D 1 → point h → load (or smoothing capacitor C 4) → point g → sub capacitor C 1 → transformer Tr secondary coil point d
　また、トランスＴsの二次コイルに生じた逆起電力Ｖsは、ｅ点側が低電位、ｂ点側が高電位の向きである。ダイオードＤ５は、この逆起電力Ｖsに対して逆バイアスとなるため電流は流れない。 Further, the back electromotive force Vs generated in the secondary coil of the transformer Ts is directed to a low potential on the point e side and a high potential on the point b side. Since the diode D5 is reverse biased with respect to the back electromotive force Vs, no current flows.
　ここで、図６に示すオフ期間の電位関係図を参照する。逆起電力ＶsによりトランスＴsの二次コイルｂ点電位がｅ点電位に対して上昇し、平滑コンデンサＣ４の一端（第１出力端Ｐ）であるｈ点電位を超えると、ダイオードＤ２が順バイアスとなり電流ｉsoffが以下の経路で流れる。
　・電流ｉsoff：トランスＴs二次コイルｂ点→ダイオードＤ２→ｈ点→負荷（又は平滑コンデンサＣ４）→ｇ点→サブコンデンサＣ２→トランスＴs二次コイルｅ点 Here, a potential relationship diagram of the off period shown in FIG. 6 is referred to. When the potential at the secondary coil b of the transformer Ts rises relative to the potential at the point e due to the back electromotive force Vs and exceeds the potential at the point h which is one end (first output end P) of the smoothing capacitor C4, the diode D2 is forward biased The current isoff flows in the following path.
· Current isoff: transformer Ts secondary coil point b → diode D2 → point h → load (or smoothing capacitor C4) → point g → sub capacitor C2 → transformer Ts secondary coil point
　オフ期間の電流ｉroff、ｉsoffは、サブコンデンサＣ１、Ｃ２をそれぞれ放電する方向に流れる。オフ期間の電流ｉroff、ｉsoffは、フライバック方式におけるフライバック電流に相当する。通常のフライバック方式では、トランスに蓄積された磁気エネルギーが放出されるが、本回路の場合、サブコンデンサＣ１、Ｃ２に蓄積されたエネルギーが放出される。 The currents iroff and isoff in the off period flow in the direction of discharging the sub capacitors C1 and C2, respectively. The currents iroff and isoff in the off period correspond to the flyback current in the flyback system. In the normal flyback method, the magnetic energy stored in the transformer is released, but in the case of this circuit, the energy stored in the sub capacitors C1 and C2 is released.
　図６のオフ期間の電位関係から判るように、ｉroffが流れるときのａ点電位は、ｇ点電位に対して、サブコンデンサＣ１の両端電圧ＶC1と逆起電力Ｖrとを加算したものとなっている。同様に、ｉsoffが流れるときのｂ点電位は、ｇ点電位に対して、サブコンデンサＣ２の両端電圧ＶC2と逆起電力Ｖsとを加算したものとなっている。 As can be seen from the potential relationship in the off period in FIG. 6, the potential at the point a when iroff flows is the sum of the voltage VC1 across the sub capacitor C1 and the back electromotive force Vr to the potential at the point g. There is. Similarly, the potential at point b when isoff flows is the sum of the potential at point g, the voltage VC2 across the sub capacitor C2 and the back electromotive force Vs.
　図６には示していないが、電流ｉroff、ｉsoffによりサブコンデンサＣ１、Ｃ２はそれぞれ放電するので、ｄ点電位、ｅ点電位はその分だけそれぞれ低下し、両端電圧ＶC1、ＶC2はそれぞれ小さくなる。 Although not shown in FIG. 6, the sub capacitors C1 and C2 are discharged by the currents iroff and isoff respectively, so the potential at the point d and the potential at the point e decrease by that amount, and the voltages VC1 and VC2 decrease.
　なお、オフ期間にトランスＴr、Ｔsの二次コイルに生じる逆起電力は、オン期間にサブコンデンサＣ１、Ｃ２に充電された電圧ＶC1、ＶC2により抑圧されるため、サブコンデンサＣ１、Ｃ２が無い場合の逆起電力に比べて小さくなる。この結果、トランスＴr、Ｔsの一次側に生じる逆起電力も小さくなるため、一次側のＦＥＴＱr、ＦＥＴＱsに要求される耐圧が軽減される。 The back electromotive force generated in the secondary coil of the transformer Tr and Ts in the off period is suppressed by the voltages VC1 and VC2 charged in the sub capacitors C1 and C2 in the on period, so there is no sub capacitor C1 or C2 Smaller than the back electromotive force of As a result, the back electromotive force generated on the primary side of the transformer Tr, Ts also decreases, and the withstand voltage required for the FET Qr, FET Qs on the primary side is reduced.
　また、トランスＴtの二次コイルに生じる逆起電力Ｖtは、ｆ点側が高電位、ｃ点側が低電位の向きであり、トランスＴr、Ｔsとは逆向きである。ダイオードＤ３は、この逆起電力Ｖtに対して逆バイアスとなるため、電流は流れない。逆起電力Ｖtによりｆ点電位がｃ点電位に対して上昇し、ｆ点電位がサブコンデンサＣ３の両端電圧ＶC3を超えると、電流ｉtoffが以下の経路で流れ、サブコンデンサＣ３を充電する。
　・電流ｉtoff：トランスＴt二次コイルｆ点→サブコンデンサＣ３→ダイオードＤ６→トランスＴｔ二次コイルｃ点 Further, the back electromotive force Vt generated in the secondary coil of the transformer Tt is in the direction of high potential at the point f side and low potential at the point c side, and is opposite to the transformer Tr and Ts. Since the diode D3 is reverse biased with respect to the back electromotive force Vt, no current flows. When the potential at point f rises relative to the potential at point c due to the back electromotive force Vt and the potential at point f exceeds the voltage VC3 across the sub capacitor C3, the current itoff flows in the following path to charge the sub capacitor C3.
Current itoff: transformer Tt secondary coil f point → sub capacitor C3 → diode D6 → transformer Tt secondary coil c point
　本回路のオフ期間の動作をまとめると次の通りである。オン期間に一次コイルに入力電流が流れたトランスにおいては、オフ期間に二次コイルに発生した逆起電力がサブコンデンサの電圧に加算される。加算された電圧が平滑コンデンサの電圧を超えると負荷に電流が流れる。一方、オン期間に一次コイルに還流が流れたトランスにおいては、オフ期間に二次コイルに発生した逆起電力がサブコンデンサの電圧を超えると、サブコンデンサを充電する方向に電流が流れる。 The operation of the off period of this circuit is summarized as follows. In the transformer in which the input current flows to the primary coil in the on period, the back electromotive force generated in the secondary coil in the off period is added to the voltage of the sub capacitor. When the added voltage exceeds the voltage of the smoothing capacitor, current flows in the load. On the other hand, in the transformer in which the return flow flows to the primary coil in the on period, when the back electromotive force generated in the secondary coil in the off period exceeds the voltage of the sub capacitor, a current flows in the direction of charging the sub capacitor.
　上記の通り、本回路では、オン期間もオフ期間も負荷へ電流を供給することが可能である。本回路では、通常のフォワード方式における外付けチョークコイルは不要である。また、通常のフライバック方式に比べてサブコンデンサＣ１、Ｃ２、Ｃ３とダイオードＤ４、Ｄ５、Ｄ６が追加されるが、これらはコスト的にもスペース的にもチョークコイルより有利である。 As described above, in this circuit, it is possible to supply current to the load during the on period and the off period. In this circuit, the external choke coil in the normal forward system is unnecessary. Also, sub-capacitors C1, C2, C3 and diodes D4, D5, D6 are added as compared to the conventional flyback method, but they are more advantageous than the choke coil in cost and space.
　また、オン期間もオフ期間も３つのトランスに電流が流れるため、トランスの利用効率が向上する。 In addition, since current flows to the three transformers during the on period and the off period, the utilization efficiency of the transformer is improved.
　Ｒ、Ｓ、Ｔ　入力端
　Ｅ　入力側基準電位端
　Ｐ　正極出力端
　Ｎ　負極出力端（出力側基準電位）
　Ｔr、Ｔs、Ｔt　トランス
　Ｌr1、Ｌs1、Ｌt1　一次コイル
　Ｌr2、Ｌs2、Ｌt2　二次コイル
　Ｑr、Ｑs、Ｑt　スイッチング素子（ＦＥＴ）
　Ｄ１、Ｄ２、Ｄ３　整流要素（出力ダイオード）
　Ｄ４、Ｄ５、Ｄ６　整流要素
　Ｃ１、Ｃ２、Ｃ３　サブコンデンサ
　Ｃ４　平滑コンデンサ R, S, T Input end E Input side reference potential end P Positive output end N Negative output end (Output side reference potential)
Tr, Ts, Tt transformer Lr1, Ls1, Lt1 Primary coil Lr2, Ls2, Lt2 Secondary coil Qr, Qs, Qt Switching element (FET)
D1, D2, D3 Rectifying element (output diode)
D4, D5, D6 Rectifying element C1, C2, C3 Sub capacitor C4 Smoothing capacitor

Claims (1)

  1. 　（ａ）三相交流が入力される第１、第２及び第３入力端（R,S,T）と、
    　（ｂ）正極出力端（P）及び負極出力端（N）と、
    　（ｃ）各々が一次コイル（Lr1,Ls1,Lt1）と二次コイル（Lr2,Ls2,Lt2）を具備し各々の一次コイルの一端が前記第１、第２及び第３入力端（R,S,T）にそれぞれ接続された第１、第２及び第３トランス（Tr,Ts,Tt）と、
    　（ｄ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の一次コイル（Lr1,Ls1,Lt1）の他端と入力側基準電位端（E）の間の各電流路を導通又は遮断するように１つの制御信号（Vg）によりオンオフ制御される第１、第２及び第３スイッチング素子（Qr,Qs,Qt）と、
    　（ｅ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の二次コイル（Lr2,Ls2,Lt2）の一端と前記負極出力端（N）の間にそれぞれ接続された第１、第２及び第３サブコンデンサ（C1,C2,C3）と、
    　（ｆ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の二次コイル（Lr2,Ls2,Lt2）の他端と前記正極出力端（P）の間にそれぞれ接続され、該二次コイルの他端から該正極出力端（P）へ流れる電流をそれぞれ導通させる第１、第２及び第３整流要素（D1,D2,D3）と、
    　（ｇ）前記第１、第２及び第３トランス（Tr,Ts,Tt）の各々の二次コイル（Lr2,Ls2,Lt2）の他端と前記負極出力端（N）の間にそれぞれ接続され、該負極出力端（N）から該二次コイルの他端へ流れる電流をそれぞれ導通させる第４、第５及び第６整流要素（D4,D5,D6）と、
    　（ｈ）前記正極出力端（P）と前記負極出力端（N）の間に接続された平滑コンデンサ（C4）と、を有することを特徴とするスイッチング電源。     (A) first, second and third input terminals (R, S, T) to which three-phase alternating current is input;
    (B) positive electrode output end (P) and negative electrode output end (N),
    (C) Each has a primary coil (Lr1, Ls1, Lt1) and a secondary coil (Lr2, Ls2, Lt2), and one end of each primary coil has the first, second and third input ends (R, S) , T) respectively connected to the first, second and third transformers (Tr, Ts, Tt),
    (D) Each current path between the other end of the primary coil (Lr1, Ls1, Lt1) of each of the first, second and third transformers (Tr, Ts, Tt) and the input side reference potential end (E) First, second and third switching elements (Qr, Qs, Qt) which are on / off controlled by one control signal (Vg) to conduct or interrupt
    (E) One end of the secondary coil (Lr2, Ls2, Lt2) of each of the first, second and third transformers (Tr, Ts, Tt) and the negative output end (N) are connected to each other First, second and third sub capacitors (C1, C2, C3),
    (F) connected between the other end of the secondary coil (Lr2, Ls2, Lt2) of each of the first, second and third transformers (Tr, Ts, Tt) and the positive electrode output end (P) First, second and third rectifying elements (D1, D2, D3) for respectively conducting a current flowing from the other end of the secondary coil to the positive electrode output end (P);
    (G) connected between the other end of the secondary coil (Lr2, Ls2, Lt2) of each of the first, second and third transformers (Tr, Ts, Tt) and the negative output end (N) Fourth, fifth and sixth rectifying elements (D4, D5, D6) for respectively conducting the current flowing from the negative electrode output end (N) to the other end of the secondary coil;
    (H) A switching power supply comprising: a smoothing capacitor (C4) connected between the positive electrode output end (P) and the negative electrode output end (N).
PCT/JP2018/018504 2017-06-23 2018-05-14 Three-phase ac insulated switching power supply WO2018235455A1 (en)

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