WO2018047750A1 - Step-down conversion circuit - Google Patents

Step-down conversion circuit Download PDF

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Publication number
WO2018047750A1
WO2018047750A1 PCT/JP2017/031692 JP2017031692W WO2018047750A1 WO 2018047750 A1 WO2018047750 A1 WO 2018047750A1 JP 2017031692 W JP2017031692 W JP 2017031692W WO 2018047750 A1 WO2018047750 A1 WO 2018047750A1
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Prior art keywords
voltage
frequency
primary
transformer
high frequency
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PCT/JP2017/031692
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French (fr)
Japanese (ja)
Inventor
陳　登
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株式会社オートネットワーク技術研究所
住友電装株式会社
住友電気工業株式会社
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Publication of WO2018047750A1 publication Critical patent/WO2018047750A1/en

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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
    • 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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters

Definitions

  • the technology disclosed in this specification relates to a step-down converter circuit, and more particularly, to a technology for generating a step-down DC voltage by stepping down a DC voltage.
  • Patent Document 1 discloses a known all-waveform zero current switching type (ZCS type) step-down converter (step-down conversion circuit).
  • a step-down conversion circuit disclosed in the present specification is a step-down conversion circuit that steps down a DC voltage to convert it to a step-down DC voltage, and is connected to a power line to which the DC voltage is supplied and the power line, Generating a voltage, superimposing the high-frequency voltage on the direct-current voltage so that the voltage value of the direct-current voltage is reduced, generating a high-frequency superimposed voltage; and inputting the high-frequency superimposed voltage; And a low-pass filter that outputs.
  • the high-frequency voltage is superimposed on the DC voltage to generate the high-frequency superimposed voltage, and the high-frequency superimposed voltage is filtered to generate the step-down DC voltage. That is, the DC voltage is converted into a step-down DC voltage without depending on the switching operation of the transistor or the like. Therefore, it is possible to reduce the generation of switching noise associated with the switching operation. Also, the conversion efficiency of the step-down converter circuit can be increased by configuring the high frequency superimposing unit so that the ratio of the power loss by the high frequency superimposing unit to the power consumption of the large capacity load is reduced. Therefore, according to the step-down converter circuit of this configuration, when applied to a large-capacity load, efficiency can be increased and noise generation can be suppressed.
  • the high-frequency superimposing unit includes a high-frequency generation circuit that generates a high-frequency primary voltage, a primary coil that is connected to the high-frequency generation circuit and receives the high-frequency primary voltage, and is connected in series with the power line.
  • a transformer including a connected secondary coil and the transformer induces a secondary voltage in a direction opposite to a voltage direction of the DC voltage in the secondary coil, and the induced secondary A voltage may be superimposed on the DC voltage as the high frequency voltage.
  • the conversion efficiency of the step-down conversion circuit of this configuration is improved as the capacity of the load is increased. That is, regarding the conversion efficiency, the step-down conversion circuit of this configuration is advantageous when applied to a high-current power circuit. Further, in the method of superimposing the high frequency voltage on the DC voltage so that the voltage value of the DC voltage is lowered, inducing a secondary voltage in the direction opposite to the voltage direction of the DC voltage in the secondary coil of the transformer It can be easily realized by setting the polarity.
  • the high-frequency generation circuit may generate a rectangular wave high-frequency voltage as the high-frequency primary voltage.
  • the voltage value of the step-down DC voltage can be easily changed by changing the rectangular width (duty ratio) of the rectangular wave.
  • the voltage value of the step-down DC voltage can be easily changed by PWM (pulse width modulation).
  • the step-down converter circuit may further include an output switch connected in series to the power supply line at a subsequent stage of the low-pass filter. According to this configuration, when the load is a battery, or when the voltage of the battery increases, the output switch is turned off to prevent the battery from returning to the low-pass filter side.
  • the efficiency when applied to a large-capacity load, the efficiency can be increased and the generation of noise can be suppressed.
  • FIG. 1 is a schematic block diagram showing a step-down converter according to an embodiment.
  • Schematic block diagram showing an example of a high-frequency voltage generation circuit Time chart showing the voltage of each part of the buck converter
  • Time chart showing the voltage of each part of another example of step-down converter
  • Schematic block diagram showing another example of a step-down converter circuit
  • a step-down converter circuit 10 according to an embodiment will be described with reference to FIGS. 1 to 4.
  • Step-down converter circuit 10 steps down DC voltage V1, which is the voltage of battery Ba, and converts it to step-down DC voltage V4.
  • the step-down converter circuit 10 is applied to the present embodiment, for example, a power circuit that is arranged for an HV vehicle on which a gasoline engine and a traveling motor are mounted and supplies power to a large-capacity load 50 such as a traveling motor. .
  • the application of the step-down converter circuit 10 is not limited to HV vehicles, and is not limited to vehicles.
  • the load to which the step-down converter circuit 10 is applied is not necessarily limited to a large capacity load.
  • the step-down converter circuit 10 includes a power line LS, an input switch SW1, a high frequency superimposing unit 11, a low-pass filter 15, and an output switch SW2.
  • the input switch SW1 When the input switch SW1 is turned on, the DC voltage V1 is supplied from the battery Ba to the power supply line LS.
  • the high frequency superimposing unit 11 is connected to the power supply line LS, generates a high frequency voltage V2, and superimposes the high frequency voltage V2 on the DC voltage V1 so that the voltage value of the DC voltage V1 decreases, thereby generating a high frequency superimposed voltage V3. To do.
  • the high frequency superimposing unit 11 includes a high frequency generation circuit 12, a backflow prevention diode D1, and a pulse transformer T1, as shown in FIG.
  • the pulse transformer T1 is an example of a “transformer” and is simply referred to as “transformer T1” hereinafter.
  • the high frequency generation circuit 12 is connected to the battery Ba, includes an inverter control unit 13 and an inverter unit 14, and generates a high frequency primary voltage VL ⁇ b> 1.
  • the high frequency generation circuit 12 generates a half-wave high frequency voltage as the high frequency primary voltage VL1.
  • the high frequency generation circuit 12 generates a rectangular wave capable of PWM (pulse width modulation) as the high frequency primary voltage VL1.
  • PWM pulse width modulation
  • the inverter unit 14 is a known inverter circuit including four semiconductor switches (S1-S4).
  • the semiconductor switches S1 and S2 are simultaneously turned on / off by the inverter control unit 13, so that, for example, a plus-side rectangular wave voltage + VL1 is formed every 180 degrees.
  • the semiconductor switches S3 and S4 are simultaneously turned on / off by the inverter control unit 13 to form, for example, a negative rectangular wave voltage ⁇ VL1 that is 180 degrees out of phase with the positive rectangular wave voltage + VL1.
  • the frequency thereof is, for example, a high frequency from 500 KHz to 1 MHz.
  • the loss of the transformer T1 can be reduced by setting the primary voltage VL1 to a high frequency.
  • the excitation inductance is 10 ⁇ H
  • the transformer turns ratio is 1: 1
  • the load resistance is 10 ⁇ (load current is 4.8 A)
  • the transformer T1 includes a primary side coil L1 connected to the high frequency generation circuit 12 to which a high frequency primary voltage VL1 (rectangular wave voltage + VL1) is input, and a secondary side coil L2 connected in series in the middle of the power supply line LS. .
  • the transformer T1 superimposes the secondary voltage VL2 induced in the secondary coil L2 on the DC voltage V1 as the high-frequency voltage V2.
  • the secondary coil L2 is induced such that a high-frequency voltage V2 opposite to the voltage direction of the DC voltage V1 is generated, that is, the voltage directions of the DC voltage V1 and the high-frequency voltage V2 are opposite (see FIG. 1), windings of the primary side coil L1 and the secondary side coil L2 are configured.
  • the secondary coil L2 of the transformer T1 in the method of superimposing the high-frequency voltage on the DC voltage so that the voltage value of the DC voltage decreases, the secondary coil L2 of the transformer T1 has a secondary in the direction opposite to the voltage direction of the DC voltage V1. Voltage VL2 is induced. This can be easily done by setting the polarity of the winding of the transformer T1.
  • V3 V1-V2.
  • the high level (maximum value) of the high frequency voltage V2 is 25V
  • the high level (maximum value) VB of the high frequency superimposed voltage V3 is 30V. It becomes.
  • the low level (minimum value) VA of the high frequency superimposed voltage V3 is 5V.
  • an exciting current is applied to the primary side of the transformer T1, and a voltage (high-frequency voltage) V2 opposite to the power supply voltage (battery Ba voltage: DC voltage V1) is generated on the secondary side.
  • the load current does not flow (or decreases). That is, the excitation voltage is provided from the primary side to the secondary side of the transformer T1, but no load current is provided from the transformer T1.
  • the load current is provided from the battery Ba when the output voltage (high frequency voltage) V2 of the transformer T1 becomes zero.
  • the load current is small, the width (amplitude) of the output voltage V2 of the transformer T1 is wide and a large excitation current is required. Conversely, when the load current is large, the width (amplitude) of the output voltage V2 of the transformer T1 is narrowed, the required excitation current is reduced, and the efficiency of the transformer T1 is increased.
  • the low-pass filter 15 is a well-known one, and is composed of, for example, a coil and a capacitor.
  • the low-pass filter 15 receives the high frequency superimposed voltage V3 and outputs a step-down DC voltage V4.
  • the average voltage value VC of the step-down DC voltage V4 is approximately 22.5V. That is, the step-down converter circuit 10 steps down the DC voltage V1 of 30V and converts it to a stepped-down DC voltage V4 having an average value of 22.5V.
  • the voltage value of the step-down DC voltage V4 can be changed. That is, in this embodiment, the amount of step-down increases as the duty ratio of the high-frequency voltage V2 increases.
  • the duty ratio of the high-frequency voltage V2, that is, the ratio of the high-level period of the high-frequency voltage V2 within the period K1 of the high-frequency voltage V2 is about 33%. In the example of FIG. It is.
  • the step-down amount when the duty ratio is 33% is 7.5V, and the step-down amount when the duty ratio is 50% is 12.5V.
  • the adjustment of the step-down amount is not limited to the duty ratio, and can be performed by changing the maximum value of the high-frequency voltage V2 by changing the winding ratio of the primary side coil L1 and the secondary side coil L2.
  • the output switch SW2 is connected in series in the middle of the power line LS in the subsequent stage of the low-pass filter 15.
  • the output switch SW2 is provided in order to prevent the voltage of the battery from increasing and the return from the load 50 side to the low-pass filter 15 side.
  • the high-frequency superimposed voltage V3 is generated by superimposing the high-frequency voltage V2 on the DC voltage V1, and the high-frequency superimposed voltage V3 is filtered by the low-pass filter 15 to thereby step-down DC.
  • a voltage V4 is generated. That is, the DC voltage V1 supplied to the power supply line LS through which a large current flows is converted into the step-down DC voltage V4 without using a direct switching operation by a transistor or the like. Therefore, it is possible to reduce the generation of switching noise associated with the switching operation.
  • the conversion efficiency of the step-down conversion circuit 10 can be increased by configuring the high frequency superposition unit 11 so that the ratio of the power loss by the high frequency superposition unit 11 to the power consumption of the large-capacity load 50 is reduced.
  • the efficiency can be increased to 98% by suppressing the loss caused by the high-frequency superposition unit 11 to 40 W. That is, in the step-down converter circuit 10 of the present embodiment, when applied to the large-capacity load 50, the efficiency can be increased and the generation of noise can be suppressed.
  • the excitation loss of the transformer T1 can be made constant regardless of the capacity of the load 50.
  • the conversion efficiency of the step-down conversion circuit 10 of this configuration is improved as the capacity of the load 50 is increased. That is, in the step-down converter circuit 10 of this embodiment, it can be said that the larger the capacity of the load 50, the more advantageous.
  • the capacity of the load 50 increases, that is, as the load current increases, the DC loss due to the secondary side coil L2 increases.
  • the DC resistance of the secondary side coil L2 is reduced by a switching method.
  • a rectangular wave (high frequency pulse signal) capable of PWM is used as the high frequency primary voltage LV1. Therefore, the voltage value of the step-down DC voltage V4 can be easily changed by changing the pulse width (duty ratio) of the high-frequency primary voltage LV1.
  • the high-frequency superimposing unit includes, for example, a high-frequency generating unit that generates a high-frequency voltage and an amplifier circuit that amplifies the generated high-frequency voltage, and the amplified high-frequency voltage is directly applied to the power supply line LS. Good.
  • the high frequency superimposing unit may be configured to be connected to the power supply line, generate a high frequency voltage, superimpose the high frequency voltage on the DC voltage so that the voltage value of the DC voltage is reduced, and generate the high frequency superimposed voltage. .
  • the high frequency generation circuit 12 may be configured by, for example, a rectangular wave generation IC.
  • the high-frequency primary voltage VL1 may be generated simply by switching a DC voltage using a transistor. In this case, although switching noise occurs, since the power is small, the level of switching noise can be reduced as compared with the case where the power supply line LS is directly switched.
  • the high-frequency primary voltage VL1 is not limited to a rectangular wave that can be PWM.
  • the high-frequency primary voltage VL1 may be a rectangular wave with a fixed duty ratio.
  • the high-frequency primary voltage VL1 may be a sine wave or may be a triangular wave.
  • the high-frequency primary voltage VL1 applied to the primary coil L1 of the transformer T1 only the plus-side rectangular wave voltage + VL1 is used, in other words, only the half wave is used.
  • a plus-side rectangular wave voltage + VL1 and a minus-side rectangular wave voltage ⁇ VL1 may be used, in other words, a full wave may be used.
  • the primary side coil L1 of the transformer T1 is one, in order to show the full wave use of the high frequency primary voltage VL1, in FIG. 5, two primary side coils L1 are described for convenience.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Inverter Devices (AREA)

Abstract

This step-down conversion circuit (10) steps down and converts the direct current voltage (V1) into a stepped-down direct current voltage (V4). The step-down conversion circuit (10) is provided with: a power line (LS) for supplying the direct current voltage (V1); a high-frequency superimposition unit (11) which is connected to the power line (LS), generates a high-frequency voltage (V2), superimposes the high-frequency voltage (V2) onto the direct current voltage (V1) to reduce the voltage level of the direct current voltage (V1), and generates a high-frequency superimposition voltage (V3); and a low-pass filter (15) which receives the high-frequency superimposition voltage (V3) and outputs the stepped-down direct current voltage (V4).

Description

降圧変換回路Buck converter circuit
　本明細書に開示される技術は、降圧変換回路に関し、詳しくは、直流電圧を降圧して降圧直流電圧を生成する技術に関する。 The technology disclosed in this specification relates to a step-down converter circuit, and more particularly, to a technology for generating a step-down DC voltage by stepping down a DC voltage.
　従来、上記、直流電圧を降圧して降圧直流電圧を生成する技術として、直流電圧をチョッパによって高周波のパルス電圧に変換し、高周波のパルス電圧をローパスフィルタによって直流電圧に戻す方法が幅広く行われている。そのようなチョッパによる方法として、例えば、特許文献１には、公知の全波形ゼロ電流スイッチング方式（ＺＣＳ方式）の降圧形コンバータ（降圧変換回路）が開示されている。 Conventionally, as a technique for generating a step-down DC voltage by stepping down a DC voltage, a method of converting a DC voltage into a high-frequency pulse voltage using a chopper and returning the high-frequency pulse voltage to a DC voltage using a low-pass filter has been widely used. Yes. As a method using such a chopper, for example, Patent Document 1 discloses a known all-waveform zero current switching type (ZCS type) step-down converter (step-down conversion circuit).
特開２００３－３０９９６７号公報JP 2003-309967 A
　しかしながら、スイッチング方式の降圧変換回路がパワー回路として使用される場合、パワー回路では高速でのスイッチングが必要とされるため、スイッチング損失、すなわち、変換損失およびスイッチングノイズが問題となる。また、近年、電気自動車等、大電流が必要とされる直流電圧源の需要の増加に伴って、大容量負荷のパワー回路として適用される際に、効率が高く、かつノイズ発生を抑制できる降圧変換回路が所望されていた。 However, when a switching-type step-down converter circuit is used as a power circuit, since the power circuit requires high-speed switching, switching loss, that is, conversion loss and switching noise becomes a problem. In recent years, with the increase in demand for DC voltage sources that require a large current, such as electric vehicles, a step-down that is highly efficient and can suppress noise generation when applied as a power circuit for a large-capacity load. A conversion circuit was desired.
　本明細書に開示される技術は、上記のような事情に基づいて完成されたものであって、大容量負荷に適用される際に、効率を高めることができ、かつノイズ発生を抑制できる降圧変換回路を提供する。 The technology disclosed in the present specification has been completed based on the above-described circumstances, and when applied to a large-capacity load, it is possible to increase efficiency and reduce noise generation. A conversion circuit is provided.
　本明細書に開示される降圧変換回路は、直流電圧を降圧して降圧直流電圧に変換する降圧変換回路であって、前記直流電圧が供給される電源線と、前記電源線に接続され、高周波電圧を生成し、前記高周波電圧を前記直流電圧の電圧値が低下するように前記直流電圧に重畳し、高周波重畳電圧を生成する高周波重畳部と、前記高周波重畳電圧を入力し、前記降圧直流電圧を出力するローパスフィルタと、を備える。 A step-down conversion circuit disclosed in the present specification is a step-down conversion circuit that steps down a DC voltage to convert it to a step-down DC voltage, and is connected to a power line to which the DC voltage is supplied and the power line, Generating a voltage, superimposing the high-frequency voltage on the direct-current voltage so that the voltage value of the direct-current voltage is reduced, generating a high-frequency superimposed voltage; and inputting the high-frequency superimposed voltage; And a low-pass filter that outputs.
　本構成によれば、直流電圧に高周波電圧を重畳して、高周波重畳電圧を生成し、高周波重畳電圧をフィルタリングすることによって降圧直流電圧が生成される。すなわち、直流電圧がトランジスタ等のスイッチング動作によらずに降圧直流電圧に変換される。そのため、スイッチング動作に伴うスイッチングノイズの発生を低減できる。また、大容量負荷の消費電力に対する高周波重畳部による電力損失の割合が低くなるように高周波重畳部を構成することによって、降圧変換回路の変換効率を高めることができる。そのため、本構成の降圧変換回路によれば、大容量負荷に適用される際に、効率を高めることができ、またノイズ発生を抑制できる。 According to this configuration, the high-frequency voltage is superimposed on the DC voltage to generate the high-frequency superimposed voltage, and the high-frequency superimposed voltage is filtered to generate the step-down DC voltage. That is, the DC voltage is converted into a step-down DC voltage without depending on the switching operation of the transistor or the like. Therefore, it is possible to reduce the generation of switching noise associated with the switching operation. Also, the conversion efficiency of the step-down converter circuit can be increased by configuring the high frequency superimposing unit so that the ratio of the power loss by the high frequency superimposing unit to the power consumption of the large capacity load is reduced. Therefore, according to the step-down converter circuit of this configuration, when applied to a large-capacity load, efficiency can be increased and noise generation can be suppressed.
　上記降圧変換回路において、前記高周波重畳部は、高周波一次電圧を生成する高周波生成回路と、前記高周波生成回路に接続され前記高周波一次電圧が入力される一次側コイルと、前記電源線の途中に直列接続された二次側コイルとを含むトランスと、を含み、前記トランスは、前記二次側コイルに、前記直流電圧の電圧方向と逆方向の二次電圧を誘起し、誘起された前記二次電圧を前記高周波電圧として前記直流電圧に重畳するようにしてもよい。
　本構成によれば、高周波電圧を直流電圧に重畳させる構成としてトランスを使用することにより、負荷の容量にかかわらず、トランスの励磁損失を一定にできる。それによって、負荷の容量が大きいほど、本構成の降圧変換回路の変換効率が良くなると言える。すなわち、変換効率に関して、本構成の降圧変換回路は、大電流のパワー回路に適用される場合に有利となる。また、高周波電圧を直流電圧の電圧値が低下するように直流電圧に重畳する方法において、トランスの二次側コイルに直流電圧の電圧方向と逆方向の二次電圧を誘起させることは、トランスの極性の設定によって容易に実現できる。 In the step-down converter circuit, the high-frequency superimposing unit includes a high-frequency generation circuit that generates a high-frequency primary voltage, a primary coil that is connected to the high-frequency generation circuit and receives the high-frequency primary voltage, and is connected in series with the power line. A transformer including a connected secondary coil, and the transformer induces a secondary voltage in a direction opposite to a voltage direction of the DC voltage in the secondary coil, and the induced secondary A voltage may be superimposed on the DC voltage as the high frequency voltage.
According to this configuration, by using the transformer as a configuration in which the high-frequency voltage is superimposed on the DC voltage, the transformer excitation loss can be made constant regardless of the capacity of the load. Accordingly, it can be said that the conversion efficiency of the step-down conversion circuit of this configuration is improved as the capacity of the load is increased. That is, regarding the conversion efficiency, the step-down conversion circuit of this configuration is advantageous when applied to a high-current power circuit. Further, in the method of superimposing the high frequency voltage on the DC voltage so that the voltage value of the DC voltage is lowered, inducing a secondary voltage in the direction opposite to the voltage direction of the DC voltage in the secondary coil of the transformer It can be easily realized by setting the polarity.
　また、上記降圧変換回路において、前記高周波生成回路は、前記高周波一次電圧として、矩形波の高周波電圧を生成するようにしてもよい。
　本構成によれば、矩形波の矩形幅（デューティ比）を変更することによって、降圧直流電圧の電圧値を容易に変更できる。言い換えれば、ＰＷＭ（パルス幅変調）によって、降圧直流電圧の電圧値を容易に変更できる。 In the step-down converter circuit, the high-frequency generation circuit may generate a rectangular wave high-frequency voltage as the high-frequency primary voltage.
According to this configuration, the voltage value of the step-down DC voltage can be easily changed by changing the rectangular width (duty ratio) of the rectangular wave. In other words, the voltage value of the step-down DC voltage can be easily changed by PWM (pulse width modulation).
　また、上記降圧変換回路において、さらに、前記ローパスフィルタの後段において、前記電源線に直列接続された出力スイッチを備えるようにしてもよい。
　本構成によれば、負荷がバッテリである場合、バッテリの電圧が上昇した場合等に、出力スイッチをオフすることにより、バッテリからローパスフィルタ側への還流を防止できる。 The step-down converter circuit may further include an output switch connected in series to the power supply line at a subsequent stage of the low-pass filter.
According to this configuration, when the load is a battery, or when the voltage of the battery increases, the output switch is turned off to prevent the battery from returning to the low-pass filter side.
　本明細書に開示される降圧変換回路によれば、大容量負荷に適用される際に、効率を高めることができ、かつノイズの発生を抑制できる。 According to the step-down converter circuit disclosed in this specification, when applied to a large-capacity load, the efficiency can be increased and the generation of noise can be suppressed.
一実施形態の降圧変換回路を示す概略的なブロック図1 is a schematic block diagram showing a step-down converter according to an embodiment. 高周波電圧生成回路の一例を示す概略的なブロック図Schematic block diagram showing an example of a high-frequency voltage generation circuit 降圧変換回路の各部の電圧を示すタイムチャートTime chart showing the voltage of each part of the buck converter 降圧変換回路の別の例の各部の電圧を示すタイムチャートTime chart showing the voltage of each part of another example of step-down converter 降圧変換回路の別の例を示す模式的なブロック図Schematic block diagram showing another example of a step-down converter circuit
　一実施形態に係る降圧変換回路１０を、図１から図４を参照しつつ説明する。
　１．降圧変換回路の構成
　降圧変換回路１０は、バッテリＢａの電圧である直流電圧Ｖ１を降圧して降圧直流電圧Ｖ４に変換する。降圧変換回路１０は、本実施形態、例えば、ガソリンエンジンと走行用モータとが搭載されたＨＶ車用に配置され、走行用モータ等の大容量負荷５０に電力を供給するパワー回路に適用される。なお、降圧変換回路１０の適用は、ＨＶ車に限られず、また車両にも限られない。また、降圧変換回路１０が適用される負荷は、必ずしも大容量負荷に限られない。 A step-down converter circuit 10 according to an embodiment will be described with reference to FIGS. 1 to 4.
1. Configuration of Step-Down Converter Circuit Step-down converter circuit 10 steps down DC voltage V1, which is the voltage of battery Ba, and converts it to step-down DC voltage V4. The step-down converter circuit 10 is applied to the present embodiment, for example, a power circuit that is arranged for an HV vehicle on which a gasoline engine and a traveling motor are mounted and supplies power to a large-capacity load 50 such as a traveling motor. . Note that the application of the step-down converter circuit 10 is not limited to HV vehicles, and is not limited to vehicles. Further, the load to which the step-down converter circuit 10 is applied is not necessarily limited to a large capacity load.
　降圧変換回路１０は、図１に示されるように、電源線ＬＳ、入力スイッチＳＷ１、高周波重畳部１１、ローパスフィルタ１５、および出力スイッチＳＷ２を含む。電源線ＬＳには、入力スイッチＳＷ１がオンされた場合に、バッテリＢａから直流電圧Ｖ１が供給される。 As shown in FIG. 1, the step-down converter circuit 10 includes a power line LS, an input switch SW1, a high frequency superimposing unit 11, a low-pass filter 15, and an output switch SW2. When the input switch SW1 is turned on, the DC voltage V1 is supplied from the battery Ba to the power supply line LS.
　高周波重畳部１１は、電源線ＬＳに接続され、高周波電圧Ｖ２を生成し、高周波電圧Ｖ２を、直流電圧Ｖ１の電圧値が低下するように直流電圧Ｖ１に重畳して、高周波重畳電圧Ｖ３を生成する。 The high frequency superimposing unit 11 is connected to the power supply line LS, generates a high frequency voltage V2, and superimposes the high frequency voltage V2 on the DC voltage V1 so that the voltage value of the DC voltage V1 decreases, thereby generating a high frequency superimposed voltage V3. To do.
　詳細には、高周波重畳部１１は、図１に示されるように、高周波生成回路１２、逆流防止用ダイオードＤ１、およびパルストランスＴ１を含む。パルストランスＴ１は、「トランス」の一例であり、以下、単に「トランスＴ１」と記す。
　高周波生成回路１２は、例えば、図２に示されるように、バッテリＢａに接続され、インバータ制御部１３とインバータ部１４とを含み、高周波一次電圧ＶＬ１を生成する。本実施形態では、高周波生成回路１２は、高周波一次電圧ＶＬ１として、半波の高周波電圧を生成する。詳細には、高周波生成回路１２は、高周波一次電圧ＶＬ１としてＰＷＭ（パルス幅変調）可能な矩形波を生成する。なお、高周波生成回路１２の電力は、バッテリＢａ以外から供給されるようにしてもよい。 Specifically, the high frequency superimposing unit 11 includes a high frequency generation circuit 12, a backflow prevention diode D1, and a pulse transformer T1, as shown in FIG. The pulse transformer T1 is an example of a “transformer” and is simply referred to as “transformer T1” hereinafter.
For example, as shown in FIG. 2, the high frequency generation circuit 12 is connected to the battery Ba, includes an inverter control unit 13 and an inverter unit 14, and generates a high frequency primary voltage VL <b> 1. In the present embodiment, the high frequency generation circuit 12 generates a half-wave high frequency voltage as the high frequency primary voltage VL1. Specifically, the high frequency generation circuit 12 generates a rectangular wave capable of PWM (pulse width modulation) as the high frequency primary voltage VL1. Note that the power of the high-frequency generation circuit 12 may be supplied from other than the battery Ba.
　インバータ部１４は、４個の半導体スイッチ（Ｓ１－Ｓ４）を含む周知のインバータ回路である。半導体スイッチＳ１およびＳ２がインバータ制御部１３によって同時にオンオフ制御されることによって、位相１８０度毎に、例えば、プラス側の矩形波電圧＋ＶＬ１が形成される。一方、半導体スイッチＳ３およびＳ４がインバータ制御部１３によって同時にオンオフ制御されることによって、プラス側の矩形波電圧＋ＶＬ１と位相が１８０度ずれた、例えばマイナス側の矩形波電圧－ＶＬ１が形成される。なお、本実施形態では、プラス側（半波）の矩形波電圧＋ＶＬ１のみが形成されるものとし、その周波数は、例えば、５００ＫＨｚから１ＭＨｚの高周波数とする。一次電圧ＶＬ１を高周波とすることによってトランスＴ１の損失を低減できる。 The inverter unit 14 is a known inverter circuit including four semiconductor switches (S1-S4). The semiconductor switches S1 and S2 are simultaneously turned on / off by the inverter control unit 13, so that, for example, a plus-side rectangular wave voltage + VL1 is formed every 180 degrees. On the other hand, the semiconductor switches S3 and S4 are simultaneously turned on / off by the inverter control unit 13 to form, for example, a negative rectangular wave voltage −VL1 that is 180 degrees out of phase with the positive rectangular wave voltage + VL1. In the present embodiment, only the plus-side (half-wave) rectangular wave voltage + VL1 is formed, and the frequency thereof is, for example, a high frequency from 500 KHz to 1 MHz. The loss of the transformer T1 can be reduced by setting the primary voltage VL1 to a high frequency.
　すなわち、通常、トランスの1次インダクタンス(励磁インダクタンス)が一定の場合、１次側入力電圧の周波数が高いほど交流抵抗（インピーダンス）が大きくなる。それによって、１次側入力電圧とトランスの１次インダクタンスが一定の場合、周波数が高い程、励磁電流が小さくなる。
　例えば、１次側入力電圧のピークを４８Ｖの正弦波、励磁インダクタンスを１０μＨ、トランスのターン数比を１：１、負荷抵抗を１０Ω（負荷電流が４．８Ａ）と仮定して解析した結果、正弦波の周波数が１００ｋＨｚの場合の励磁電流が約１１．２２Ａ（トランス１次側の電流＝１２．２Ａ）、５００ｋＨｚの場合の励磁電流が２．０５Ａ（トランス1次側の電流＝５．２Ａ）になる。そのため、同じ出力電流（４．８Ａ）の場合、１次側の電流が小さい程、回路損失が小さくなるため、高周波の方の損失が小さくなる。 That is, normally, when the primary inductance (excitation inductance) of the transformer is constant, the higher the frequency of the primary side input voltage, the greater the AC resistance (impedance). Thereby, when the primary side input voltage and the primary inductance of the transformer are constant, the higher the frequency, the smaller the exciting current.
For example, as a result of analysis assuming that the peak of the primary side input voltage is 48V sine wave, the excitation inductance is 10 μH, the transformer turns ratio is 1: 1, the load resistance is 10Ω (load current is 4.8 A), When the frequency of the sine wave is 100 kHz, the exciting current is about 11.22 A (current on the transformer primary side = 12.2 A), and when 500 kHz, the exciting current is 2.05 A (current on the transformer primary side = 5.2 A). )become. For this reason, in the case of the same output current (4.8 A), the smaller the primary current, the smaller the circuit loss, and thus the higher frequency loss.
　トランスＴ１は、高周波生成回路１２に接続され高周波一次電圧ＶＬ１（矩形波電圧＋ＶＬ１）が入力される一次側コイルＬ１と、電源線ＬＳの途中に直列接続された二次側コイルＬ２と、を含む。トランスＴ１は、二次側コイルＬ２に誘起された二次電圧ＶＬ２を高周波電圧Ｖ２として直流電圧Ｖ１に重畳する。なお、二次側コイルＬ２に、直流電圧Ｖ１の電圧方向と逆方向の高周波電圧Ｖ２が誘起されるように、すなわち、直流電圧Ｖ１と高周波電圧Ｖ２の電圧方向が逆方向となるように（図１の矢印参照）、一次側コイルＬ１および二次側コイルＬ２の巻き線が構成されている。すなわち、本実施形態では、高周波電圧を直流電圧の電圧値が低下するように直流電圧に重畳する方法において、トランスＴ１の二次側コイルＬ２に、直流電圧Ｖ１の電圧方向と逆方向の二次電圧ＶＬ２が誘起される。これは、トランスＴ１の巻き線の極性の設定によって容易に行える。 The transformer T1 includes a primary side coil L1 connected to the high frequency generation circuit 12 to which a high frequency primary voltage VL1 (rectangular wave voltage + VL1) is input, and a secondary side coil L2 connected in series in the middle of the power supply line LS. . The transformer T1 superimposes the secondary voltage VL2 induced in the secondary coil L2 on the DC voltage V1 as the high-frequency voltage V2. The secondary coil L2 is induced such that a high-frequency voltage V2 opposite to the voltage direction of the DC voltage V1 is generated, that is, the voltage directions of the DC voltage V1 and the high-frequency voltage V2 are opposite (see FIG. 1), windings of the primary side coil L1 and the secondary side coil L2 are configured. That is, in the present embodiment, in the method of superimposing the high-frequency voltage on the DC voltage so that the voltage value of the DC voltage decreases, the secondary coil L2 of the transformer T1 has a secondary in the direction opposite to the voltage direction of the DC voltage V1. Voltage VL2 is induced. This can be easily done by setting the polarity of the winding of the transformer T1.
　そのため、直流電圧Ｖ１、高周波電圧Ｖ２、および高周波重畳電圧Ｖ３の関係は、Ｖ３＝Ｖ１－Ｖ２となる。図３に示されるように、例えば、直流電圧Ｖ１の電圧値を３０Ｖとし、高周波電圧Ｖ２のハイレベル（最大値）を２５Ｖとすると、高周波重畳電圧Ｖ３のハイレベル（最大値）ＶＢは、３０Ｖとなる。また、高周波重畳電圧Ｖ３のローレベル（最小値）ＶＡは、５Ｖとなる。 Therefore, the relationship between the DC voltage V1, the high-frequency voltage V2, and the high-frequency superimposed voltage V3 is V3 = V1-V2. As shown in FIG. 3, for example, when the voltage value of the DC voltage V1 is 30V and the high level (maximum value) of the high frequency voltage V2 is 25V, the high level (maximum value) VB of the high frequency superimposed voltage V3 is 30V. It becomes. Further, the low level (minimum value) VA of the high frequency superimposed voltage V3 is 5V.
　すなわち、本実施形態ではトランスＴ１の1次側に励磁電流を印加し、２次側に電源電圧（バッテリＢａの電圧：直流電圧Ｖ１）と逆方向の電圧（高周波電圧）Ｖ２を生成し、それによって、負荷電流が流れなくなる（或いは小さくなる）。つまり、トランスＴ１の１次側から２次側に励磁電圧を提供するが、トランスＴ１からは負荷電流を提供しない。負荷電流は、トランスＴ１の出力電圧（高周波電圧）Ｖ２がゼロになるときバッテリＢａから提供される。
　また、負荷電流が小さい時、トランスＴ１の出力電圧Ｖ２の幅（振幅）が広く、大きな励磁電流が必要になる。逆に負荷電流が大きい時、トランスＴ１の出力電圧Ｖ２の幅（振幅）が狭くなり、必要な励磁電流が小さくなり、トランスＴ１としての効率が高くなる。 That is, in the present embodiment, an exciting current is applied to the primary side of the transformer T1, and a voltage (high-frequency voltage) V2 opposite to the power supply voltage (battery Ba voltage: DC voltage V1) is generated on the secondary side. As a result, the load current does not flow (or decreases). That is, the excitation voltage is provided from the primary side to the secondary side of the transformer T1, but no load current is provided from the transformer T1. The load current is provided from the battery Ba when the output voltage (high frequency voltage) V2 of the transformer T1 becomes zero.
When the load current is small, the width (amplitude) of the output voltage V2 of the transformer T1 is wide and a large excitation current is required. Conversely, when the load current is large, the width (amplitude) of the output voltage V2 of the transformer T1 is narrowed, the required excitation current is reduced, and the efficiency of the transformer T1 is increased.
　ローパスフィルタ１５は周知のものであり、例えば、コイルおよびコンデンサによって構成される。ローパスフィルタ１５は、高周波重畳電圧Ｖ３を入力し、降圧直流電圧Ｖ４を出力する。降圧直流電圧Ｖ４の平均電圧値ＶＣは、およそ２２．５Ｖである。すなわち、降圧変換回路１０は、３０Ｖの直流電圧Ｖ１を、降圧して平均値２２．５Ｖの降圧直流電圧Ｖ４に変換する。 The low-pass filter 15 is a well-known one, and is composed of, for example, a coil and a capacitor. The low-pass filter 15 receives the high frequency superimposed voltage V3 and outputs a step-down DC voltage V4. The average voltage value VC of the step-down DC voltage V4 is approximately 22.5V. That is, the step-down converter circuit 10 steps down the DC voltage V1 of 30V and converts it to a stepped-down DC voltage V4 having an average value of 22.5V.
　なお、本実施形態では、ＰＷＭ信号である高周波一次電圧ＶＬ１のパルス幅（デューティ比）を変更することによって、言い換えれば、高周波電圧Ｖ２のパルス幅（デューティ比）を変更することによって、図４に示されるように、降圧直流電圧Ｖ４の電圧値を変更することができる。すなわち、本実施形態では、高周波電圧Ｖ２のデューティ比を大きくするほど、降圧量が大きくなる。図３の例では高周波電圧Ｖ２のデューティ比、すなわち、高周波電圧Ｖ２の周期Ｋ１内における高周波電圧Ｖ２のハイレベル期間の割合が、およそ３３％であり、図４の例ではデューティ比がおよそ５０％である。デューティ比が３３％の場合の降圧量は、７．５Ｖであり、デューティ比が５０％の場合の降圧量は、１２．５Ｖである。なお、降圧量の調整は、デューティ比に限られず、一次側コイルＬ１と二次側コイルＬ２の巻き線比を変えて、高周波電圧Ｖ２の最大値を変更することによっても可能である。 In the present embodiment, by changing the pulse width (duty ratio) of the high-frequency primary voltage VL1 that is a PWM signal, in other words, by changing the pulse width (duty ratio) of the high-frequency voltage V2, FIG. As shown, the voltage value of the step-down DC voltage V4 can be changed. That is, in this embodiment, the amount of step-down increases as the duty ratio of the high-frequency voltage V2 increases. In the example of FIG. 3, the duty ratio of the high-frequency voltage V2, that is, the ratio of the high-level period of the high-frequency voltage V2 within the period K1 of the high-frequency voltage V2 is about 33%. In the example of FIG. It is. The step-down amount when the duty ratio is 33% is 7.5V, and the step-down amount when the duty ratio is 50% is 12.5V. The adjustment of the step-down amount is not limited to the duty ratio, and can be performed by changing the maximum value of the high-frequency voltage V2 by changing the winding ratio of the primary side coil L1 and the secondary side coil L2.
　出力スイッチＳＷ２は、ローパスフィルタ１５の後段において、電源線ＬＳの途中に直列接続されている。出力スイッチＳＷ２は、負荷５０がバッテリの場合に、バッテリの電圧が上昇して、負荷５０側から、ローパスフィルタ１５側への還流を防止するために設けられている。 The output switch SW2 is connected in series in the middle of the power line LS in the subsequent stage of the low-pass filter 15. When the load 50 is a battery, the output switch SW2 is provided in order to prevent the voltage of the battery from increasing and the return from the load 50 side to the low-pass filter 15 side.
　２．本実施形態の効果
　本実施形態の降圧変換回路１０では、直流電圧Ｖ１に高周波電圧Ｖ２を重畳して、高周波重畳電圧Ｖ３を生成し、高周波重畳電圧Ｖ３をローパスフィルタ１５によってフィルタリングすることによって降圧直流電圧Ｖ４が生成される。すなわち、大電流が流れる電源線ＬＳに供給される直流電圧Ｖ１が、トランジスタ等による直接のスイッチング動作によらずに降圧直流電圧Ｖ４に変換される。そのため、スイッチング動作に伴うスイッチングノイズの発生を低減できる。 2. Effects of the present embodiment In the step-down converter circuit 10 of the present embodiment, the high-frequency superimposed voltage V3 is generated by superimposing the high-frequency voltage V2 on the DC voltage V1, and the high-frequency superimposed voltage V3 is filtered by the low-pass filter 15 to thereby step-down DC. A voltage V4 is generated. That is, the DC voltage V1 supplied to the power supply line LS through which a large current flows is converted into the step-down DC voltage V4 without using a direct switching operation by a transistor or the like. Therefore, it is possible to reduce the generation of switching noise associated with the switching operation.
　また、大容量負荷５０の消費電力に対する高周波重畳部１１による電力損失の割合が低くなるように高周波重畳部１１を構成することによって、降圧変換回路１０の変換効率を高めることができる。例えば、大容量負荷５０の消費電力が２０００Ｗ（ワット）である場合、高周波重畳部１１による損失を４０Ｗに抑えることによって、効率を９８％まで高めることができる。すなわち、本実施形態の降圧変換回路１０では、大容量負荷５０に適用される際に、効率を高めることができ、またノイズ発生を抑制できる。 Further, the conversion efficiency of the step-down conversion circuit 10 can be increased by configuring the high frequency superposition unit 11 so that the ratio of the power loss by the high frequency superposition unit 11 to the power consumption of the large-capacity load 50 is reduced. For example, when the power consumption of the large-capacity load 50 is 2000 W (watts), the efficiency can be increased to 98% by suppressing the loss caused by the high-frequency superposition unit 11 to 40 W. That is, in the step-down converter circuit 10 of the present embodiment, when applied to the large-capacity load 50, the efficiency can be increased and the generation of noise can be suppressed.
　また、高周波電圧Ｖ２を直流電圧Ｖ１に重畳させる構成としてトランスＴ１を使用することにより、負荷５０の容量にかかわらず、トランスＴ１の励磁損失を一定にできる。それによって、負荷５０の容量が大きいほど、本構成の降圧変換回路１０の変換効率が良くなる。すなわち、本実施形態の降圧変換回路１０では、効率的に、負荷５０の容量が大きいほど有利であると言える。
　なお、負荷５０の容量が大きくなるにしたがって、すなわち、負荷電流が大きくなるにしたがって二次側コイルＬ２による直流損失が増加するが、通常、二次側コイルＬ２の直流抵抗は、スイッチング方式の降圧変換回路に使用されるＦＥＴ等の半導体スイッチング素子のオン抵抗に比べて小さい。そのため、本実施形態では、スイッチング方式の降圧変換回路と比べて、直流損失を低減でき、それによって降圧変換回路としての効率を高めることができる。 Further, by using the transformer T1 as a configuration in which the high-frequency voltage V2 is superimposed on the DC voltage V1, the excitation loss of the transformer T1 can be made constant regardless of the capacity of the load 50. Thereby, the conversion efficiency of the step-down conversion circuit 10 of this configuration is improved as the capacity of the load 50 is increased. That is, in the step-down converter circuit 10 of this embodiment, it can be said that the larger the capacity of the load 50, the more advantageous.
Note that, as the capacity of the load 50 increases, that is, as the load current increases, the DC loss due to the secondary side coil L2 increases. Usually, the DC resistance of the secondary side coil L2 is reduced by a switching method. It is smaller than the on-resistance of semiconductor switching elements such as FETs used in the conversion circuit. For this reason, in the present embodiment, it is possible to reduce the direct current loss as compared with the switching-type step-down converter circuit, thereby increasing the efficiency as the step-down converter circuit.
　また、高周波一次電圧ＬＶ１として、ＰＷＭが可能な矩形波（高周波パルス信号）が使用される。そのため、高周波一次電圧ＬＶ１のパルス幅（デューティ比）を変更することによって、降圧直流電圧Ｖ４の電圧値を容易に変更できる。 Further, a rectangular wave (high frequency pulse signal) capable of PWM is used as the high frequency primary voltage LV1. Therefore, the voltage value of the step-down DC voltage V4 can be easily changed by changing the pulse width (duty ratio) of the high-frequency primary voltage LV1.
　＜他の実施形態＞
　本発明は上記記述及び図面によって説明した実施形態に限定されるものではなく、例えば次のような実施形態も本発明の技術的範囲に含まれる。 <Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
　（１）上記実施形態では、高周波重畳部を高周波生成回路１２とトランスＴ１とによって構成する例を示したがこれに限られない。高周波重畳部は、例えば、高周波電圧を生成する高周波生成部と、生成された高周波電圧を増幅する増幅回路とを含み、増幅された高周波電圧を直接、電源線ＬＳに印加する構成であってもよい。高周波重畳部は、要は、電源線に接続され、高周波電圧を生成し、高周波電圧を直流電圧の電圧値が低下するように直流電圧に重畳し、高周波重畳電圧を生成する構成であればよい。 (1) In the above-described embodiment, an example in which the high-frequency superimposing unit is configured by the high-frequency generation circuit 12 and the transformer T1 has been described, but the present invention is not limited thereto. The high-frequency superimposing unit includes, for example, a high-frequency generating unit that generates a high-frequency voltage and an amplifier circuit that amplifies the generated high-frequency voltage, and the amplified high-frequency voltage is directly applied to the power supply line LS. Good. In short, the high frequency superimposing unit may be configured to be connected to the power supply line, generate a high frequency voltage, superimpose the high frequency voltage on the DC voltage so that the voltage value of the DC voltage is reduced, and generate the high frequency superimposed voltage. .
　（２）上記実施形態では、高周波生成回路１２をインバータ制御部１３とインバータ部１４とによって構成する例を示したが、これに限られない。高周波生成回路１２は、例えば、矩形波生成ＩＣによって構成されてもよい。あるいは、単に、直流電圧をトランジスタによってスイッチングして高周波一次電圧ＶＬ１を生成してもよい。この場合、スイッチングノイズが発生するが、電力が小さいため、電源線ＬＳを直接、スイッチングする場合と比べて、スイッチングノイズのレベルを低減できる。
　また、高周波一次電圧ＶＬ１は、ＰＷＭ可能な矩形波に限られない。例えば、高周波一次電圧ＶＬ１は、デューティ比固定の矩形波であってもよい。あるいは、高周波一次電圧ＶＬ１は、正弦波であってもよいし、さらには三角波であってもよい。 (2) In the above-described embodiment, the example in which the high-frequency generation circuit 12 is configured by the inverter control unit 13 and the inverter unit 14 has been described, but the present invention is not limited thereto. The high frequency generation circuit 12 may be configured by, for example, a rectangular wave generation IC. Alternatively, the high-frequency primary voltage VL1 may be generated simply by switching a DC voltage using a transistor. In this case, although switching noise occurs, since the power is small, the level of switching noise can be reduced as compared with the case where the power supply line LS is directly switched.
The high-frequency primary voltage VL1 is not limited to a rectangular wave that can be PWM. For example, the high-frequency primary voltage VL1 may be a rectangular wave with a fixed duty ratio. Alternatively, the high-frequency primary voltage VL1 may be a sine wave or may be a triangular wave.
　（３）上記実施形態では、トランスＴ１の一次側コイルＬ１に印加される高周波一次電圧ＶＬ１として、プラス側の矩形波電圧＋ＶＬ１のみを使用する、言い換えれば、半波のみを使用する例を示したが、これに限られない。図５に示すように、プラス側の矩形波電圧＋ＶＬ１、およびマイナス側の矩形波電圧－ＶＬ１を使用する、言い換えれば、全波を使用するようにしてもよい。なお、トランスＴ１の一次側コイルＬ１は一個であるが、図５においては、高周波一次電圧ＶＬ１の全波使用を示すために、便宜上、一次側コイルＬ１が二個、記載されている。 (3) In the above embodiment, as the high-frequency primary voltage VL1 applied to the primary coil L1 of the transformer T1, only the plus-side rectangular wave voltage + VL1 is used, in other words, only the half wave is used. However, it is not limited to this. As shown in FIG. 5, a plus-side rectangular wave voltage + VL1 and a minus-side rectangular wave voltage −VL1 may be used, in other words, a full wave may be used. In addition, although the primary side coil L1 of the transformer T1 is one, in order to show the full wave use of the high frequency primary voltage VL1, in FIG. 5, two primary side coils L1 are described for convenience.
１０…降圧変換回路
１１…高周波重畳部
１２…高周波生成回路
１３…インバータ制御部
１４…インバータ部
１５…ローパスフィルタ
Ｂａ…バッテリ
Ｌ１…トランスの一次コイル
Ｌ２…トランスの二次コイル
ＳＷ２…出力スイッチ
Ｔ１…パルストランス DESCRIPTION OF SYMBOLS 10 ... Buck converter circuit 11 ... High frequency superposition part 12 ... High frequency generation circuit 13 ... Inverter control part 14 ... Inverter part 15 ... Low pass filter Ba ... Battery primary coil L2 ... Transformer secondary coil SW2 ... Output switch T1 ... Pulse transformer

Claims (4)

  1. 　直流電圧を降圧して降圧直流電圧に変換する降圧変換回路であって、
    　前記直流電圧が供給される電源線と、
    　前記電源線に接続され、高周波電圧を生成し、前記高周波電圧を前記直流電圧の電圧値が低下するように前記直流電圧に重畳し、高周波重畳電圧を生成する高周波重畳部と、
    　前記高周波重畳電圧を入力し、前記降圧直流電圧を出力するローパスフィルタと、を備えた降圧変換回路。     A step-down conversion circuit that steps down a DC voltage and converts it to a step-down DC voltage,
    A power supply line to which the DC voltage is supplied;
    A high-frequency superimposing unit that is connected to the power supply line, generates a high-frequency voltage, superimposes the high-frequency voltage on the DC voltage so that a voltage value of the DC voltage decreases, and generates a high-frequency superimposed voltage;
    A step-down conversion circuit comprising: a low-pass filter that inputs the high-frequency superimposed voltage and outputs the step-down DC voltage.
  2. 　請求項１に記載の降圧変換回路において、
    　前記高周波重畳部は、
    　高周波一次電圧を生成する高周波生成回路と、
    　前記高周波生成回路に接続され前記高周波一次電圧が入力される一次側コイルと、前記電源線の途中に直列接続された二次側コイルとを含むトランスと、を含み、
    　前記トランスは、前記二次側コイルに、前記直流電圧の電圧方向と逆方向の二次電圧を誘起し、誘起された前記二次電圧を前記高周波電圧として前記直流電圧に重畳する、降圧変換回路。     The step-down converter circuit according to claim 1,
    The high frequency superimposing unit is
    A high frequency generating circuit for generating a high frequency primary voltage;
    A transformer including a primary side coil connected to the high frequency generation circuit and receiving the high frequency primary voltage, and a secondary side coil connected in series in the middle of the power line,
    The transformer induces a secondary voltage in a direction opposite to the voltage direction of the DC voltage to the secondary side coil, and superimposes the induced secondary voltage on the DC voltage as the high frequency voltage. .
  3. 　請求項２に記載の降圧変換回路において、
    　前記高周波生成回路は、前記高周波一次電圧として、矩形波の高周波電圧を生成する、降圧変換回路。     The step-down converter circuit according to claim 2,
    The step-down converter circuit, wherein the high-frequency generation circuit generates a rectangular high-frequency voltage as the high-frequency primary voltage.
  4. 　請求項１から請求項３の何れか一項に記載の降圧変換回路において、さらに、
    　前記ローパスフィルタの後段において、前記電源線に直列接続された出力スイッチを備える、降圧変換回路。     The step-down converter circuit according to any one of claims 1 to 3, further comprising:
    A step-down conversion circuit comprising an output switch connected in series to the power supply line at a subsequent stage of the low-pass filter.
PCT/JP2017/031692 2016-09-08 2017-09-04 Step-down conversion circuit WO2018047750A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57118419U (en) * 1981-01-09 1982-07-22
JP2004212376A (en) * 2002-11-11 2004-07-29 Matsushita Electric Works Ltd Leakage detecting device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57118419U (en) * 1981-01-09 1982-07-22
JP2004212376A (en) * 2002-11-11 2004-07-29 Matsushita Electric Works Ltd Leakage detecting device

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