JPWO2005088819A1 - Switching power supply - Google Patents

Switching power supply Download PDF

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JPWO2005088819A1
JPWO2005088819A1 JP2006510919A JP2006510919A JPWO2005088819A1 JP WO2005088819 A1 JPWO2005088819 A1 JP WO2005088819A1 JP 2006510919 A JP2006510919 A JP 2006510919A JP 2006510919 A JP2006510919 A JP 2006510919A JP WO2005088819 A1 JPWO2005088819 A1 JP WO2005088819A1
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input
power supply
switching power
control circuit
primary
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修 廣村
修 廣村
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Panasonic Corp
Panasonic Holdings Corp
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Panasonic Corp
Matsushita Electric Industrial Co Ltd
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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/005—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting using a power saving mode
    • 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
    • H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—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 with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Dc-Dc Converters (AREA)

Abstract

スイッチング電源装置の交流入力切断時に交流入力端子間の電圧レベルを検知し、所定レベル以下になった際に１次制御回路の発振動作を停止する入力電圧レベル検知回路を有するスイッチング電源装置を提供する。このようにして、軽負荷時の交流入力切断時の直流出力電圧を所定時間内に立ち下げることが可能で、かつ軽負荷時の消費電力を抑えることが可能となる。Provided is a switching power supply device having an input voltage level detection circuit that detects a voltage level between alternating current input terminals when the alternating current input of the switching power supply device is cut off, and stops an oscillation operation of a primary control circuit when the voltage level becomes lower than a predetermined level. . In this way, the DC output voltage at the time of AC input disconnection at light load can be lowered within a predetermined time, and the power consumption at light load can be suppressed.

Description

本発明は、各種電子機器に用いられるスイッチング電源装置に関する。  The present invention relates to a switching power supply device used for various electronic devices.

従来のスイッチング電源装置について、図２を用いて説明する。軽負荷時の交流入力切断時に直流出力電圧を所定時間内に立ち下げるために、図２に示されるように入力電解コンデンサ用放電抵抗８を用いたり、あるいは２次側ブリーダ抵抗１３を用いることが一般的であった。  A conventional switching power supply device will be described with reference to FIG. In order to cause the DC output voltage to fall within a predetermined time when the AC input is cut at light load, the input electrolytic capacitor discharge resistor 8 or the secondary bleeder resistor 13 may be used as shown in FIG. It was general.

すなわち、このスイッチング電源装置は、交流入力端子１ａ，１ｂ、１次側整流平滑回路２、スイッチングトランス３、１次巻線３ａ、バイアス用の１次制御巻線３ｂ、２次巻線３ｃ、メインスイッチング素子４、１次制御用平滑回路５、２次側整流平滑回路６、直流出力端子（陽極，陰極）７ａ，７ｂ、１次制御回路９、フォトカプラ１０、定電圧制御回路１１、１次制御回路用起動抵抗１２とを備え、１次側整流平滑回路２の陽極と陰極間に入力電解コンデンサ用放電抵抗８を接続し、直流出力端子７ａ，７ｂ間に２次側ブリーダ抵抗１３を接続している。  That is, this switching power supply device includes AC input terminals 1a and 1b, a primary side rectifying and smoothing circuit 2, a switching transformer 3, a primary winding 3a, a bias primary control winding 3b, a secondary winding 3c, a main Switching element 4, primary control smoothing circuit 5, secondary side rectification smoothing circuit 6, DC output terminals (anode, cathode) 7a, 7b, primary control circuit 9, photocoupler 10, constant voltage control circuit 11, primary The control circuit start resistor 12 is provided. The input electrolytic capacitor discharge resistor 8 is connected between the anode and the cathode of the primary side rectifying and smoothing circuit 2, and the secondary bleeder resistor 13 is connected between the DC output terminals 7a and 7b. is doing.

この構成により、軽負荷時の交流入力切断が生じると、１次側整流平滑回路２内に設けられた入力電解コンデンサ２ａおよび２次側整流平滑回路６の出力電解コンデンサ６ａに蓄えられている電荷が放電されるため、直流出力電圧を所定の時間内に立ち下げることができる。なお、このような構成を有するスイッチング電源装置の例が特開平２−９７２７７号公報に開示されている。  With this configuration, when AC input disconnection occurs during light load, the charge stored in the input electrolytic capacitor 2a provided in the primary side rectifying and smoothing circuit 2 and the output electrolytic capacitor 6a of the secondary side rectifying and smoothing circuit 6 Is discharged, the DC output voltage can be lowered within a predetermined time. An example of a switching power supply device having such a configuration is disclosed in Japanese Patent Laid-Open No. 2-97277.

しかしながら、この従来の構成は、軽負荷時の交流入力切断時に直流出力電圧を所定時間内に立ち下げることは可能であるが、常時、入力電解コンデンサ用放電抵抗８や２次側ブリーダ抵抗１３が接続された構成である。その結果、電源の効率が低下するとともに、特に軽負荷時の消費電力を抑えることが困難になるという課題を有している。  However, this conventional configuration can drop the DC output voltage within a predetermined time when the AC input is cut off at a light load, but the input electrolytic capacitor discharge resistor 8 and the secondary bleeder resistor 13 are always connected. It is a connected configuration. As a result, there is a problem that the efficiency of the power source is lowered and it is difficult to suppress power consumption particularly at a light load.

本発明は、スイッチング電源装置の交流入力切断時に交流入力端子間の電圧レベルを検知し、所定レベル以下になった際に１次制御回路の発振動作を停止する入力電圧レベル検知回路を設けたスイッチング電源装置を提供する。  The present invention provides a switching circuit provided with an input voltage level detection circuit that detects a voltage level between AC input terminals when an AC input of a switching power supply device is disconnected, and stops an oscillation operation of a primary control circuit when the voltage level falls below a predetermined level. A power supply is provided.

本発明によれば、軽負荷時の交流入力切断時に素早く１次制御回路の動作を停止させることができる。その結果、１次側整流平滑回路の入力電解コンデンサの蓄積電荷を放電させることなく、直流出力電圧を一定時間内に立ち下げることが可能になるとともに、入力電解コンデンサ用放電抵抗や２次側ブリーダ抵抗が不要になるため、軽負荷時の消費電力を大幅に軽減させることができる。  According to the present invention, it is possible to quickly stop the operation of the primary control circuit when the AC input is disconnected at a light load. As a result, the DC output voltage can be lowered within a predetermined time without discharging the accumulated charge of the input electrolytic capacitor of the primary side rectifying and smoothing circuit, and the input electrolytic capacitor discharge resistor and secondary side bleeder can be reduced. Since no resistor is required, power consumption at light load can be greatly reduced.

図１は本発明のスイッチング電源装置の概略構成を示す回路図である。FIG. 1 is a circuit diagram showing a schematic configuration of a switching power supply device of the present invention. 図２は従来のスイッチング電源装置の概略構成を示す回路図である。FIG. 2 is a circuit diagram showing a schematic configuration of a conventional switching power supply apparatus.

符号の説明Explanation of symbols

１ａ，１ｂ 交流入力端子
２ １次側整流平滑回路
２ａ 入力電解コンデンサ
３ スイッチングトランス
３ａ １次巻線
３ｂ １次制御巻線
３ｃ ２次巻線
４ メインスイッチング素子
５ １次制御用平滑回路
６ ２次側整流平滑回路
６ａ 出力電解コンデンサ
７ａ，７ｂ 直流出力端子（陽極、陰極）
８ 入力電解コンデンサ用放電抵抗
９ １次制御回路
１０ フォトカプラ
１１ 定電圧制御回路
１２ １次制御回路用起動抵抗
１３ ２次側ブリーダ抵抗
１４ コンデンサ
１５，１６ 抵抗
１７ スイッチ素子
１８ ダイオード
１９ 入力電圧レベル検知回路1a, 1b AC input terminal 2 Primary side rectifying smoothing circuit 2a Input electrolytic capacitor 3 Switching transformer 3a Primary winding 3b Primary control winding 3c Secondary winding 4 Main switching element 5 Primary control smoothing circuit 6 Secondary Side rectification smoothing circuit 6a Output electrolytic capacitor 7a, 7b DC output terminal (anode, cathode)
8 Input Electrolytic Capacitor Discharge Resistor 9 Primary Control Circuit 10 Photocoupler 11 Constant Voltage Control Circuit 12 Primary Control Circuit Startup Resistor 13 Secondary Side Bleeder Resistor 14 Capacitors 15 and 16 Resistor 17 Switch Element 18 Diode 19 Input Voltage Level Detection circuit

以下、本発明の一実施の形態について図面を用いて説明する。  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

図１に示すように本発明のスイッチング電源装置は、交流入力端子１ａ、１ｂ、１次側整流平滑回路２、スイッチングトランス３、１次巻線３ａ、バイアス用の１次制御巻線３ｂ、２次巻線３ｃ、メインスイッチング素子４、１次制御用平滑回路５、２次側整流平滑回路６、直流出力端子（陽極，陰極）７ａ，７ｂ、１次制御回路９、フォトカプラ１０、定電圧制御回路１１、１次制御回路用起動抵抗１１、コンデンサ１４、抵抗１５、１６、１次制御回路の動作を停止するためのスイッチ素子１７、ダイオード１８、入力電圧レベル検知回路１９とを備えている。そして、入力電圧レベル検知回路１９の一端を交流入力端子１ａに接続し、ダイオード１８を介してコンデンサ１４へ接続し、コンデンサ１４の陰極を交流入力端子１ｂに接続し、さらに、コンデンサ１４の両端へ抵抗１５、１６を接続し、入力電圧を分圧したものをスイッチ素子１７のベースへ供給するように構成されている。この入力電圧が所定電圧以下になるとスイッチ素子１７がＯＦＦとなる。なお、所定電圧とは、第一に交流入力瞬時停電発生に対してスイッチ素子１７が例えば８０ミリ秒以上ＯＦＦせず、第二に交流入力切断時から例えば３秒以内にスイッチ素子１７がＯＦＦする電圧である。  As shown in FIG. 1, the switching power supply device of the present invention includes AC input terminals 1a, 1b, a primary side rectifying / smoothing circuit 2, a switching transformer 3, a primary winding 3a, a bias primary control winding 3b, 2 Secondary winding 3c, main switching element 4, primary control smoothing circuit 5, secondary rectification smoothing circuit 6, DC output terminals (anode, cathode) 7a, 7b, primary control circuit 9, photocoupler 10, constant voltage The control circuit 11 includes a primary control circuit starting resistor 11, a capacitor 14, resistors 15 and 16, a switch element 17 for stopping the operation of the primary control circuit, a diode 18, and an input voltage level detection circuit 19. . Then, one end of the input voltage level detection circuit 19 is connected to the AC input terminal 1 a, connected to the capacitor 14 via the diode 18, the cathode of the capacitor 14 is connected to the AC input terminal 1 b, and further to both ends of the capacitor 14. The resistors 15 and 16 are connected, and the input voltage divided is supplied to the base of the switch element 17. When the input voltage becomes a predetermined voltage or less, the switch element 17 is turned off. The predetermined voltage means that the switch element 17 is not turned off for 80 milliseconds or more, for example, when an AC input instantaneous power failure occurs, and secondly, the switch element 17 is turned off, for example, within 3 seconds after the AC input is disconnected. Voltage.

ここで、コンデンサ１４として、所定の容量を有するコンデンサを用いる。この所定の容量とは、以下の条件を満たす容量であれば任意に選択できる。第一に交流入力瞬時停電発生に対して直流出力電圧が例えば８０ミリ秒以上保持され、第二に交流入力切断時から例えば３秒以内にコンデンサ１４が放電するような容量であればよい。つまり、前記条件を満たす容量であれば任意に選定できる。そして、コンデンサ１４の電圧が低下するとスイッチ素子１７がＯＦＦとなるように構成されている。なお、上記保持時間は入力電解コンデンサ２ａにより決まるものである。その結果、軽負荷時において交流入力が切断されると、素早く１次制御回路９の発振動作が停止され、１次側整流平滑回路２の入力電解コンデンサ２ａに蓄積された電荷が２次側に変換されなくなるので、直流出力を所定時間内に立ち下げることが可能となる。また、１次制御回路９の起動に対し、コンデンサ１４の陽極に接続された１次制御回路用起動抵抗１２を介して入力投入時に電流を供給し、１次制御回路９の発振動作を開始するように構成している。その結果、入力切断時に入力電解コンデンサ２ａに蓄積されている電荷により１次制御回路９が再起動する等の不具合が発生しない。  Here, a capacitor having a predetermined capacity is used as the capacitor 14. The predetermined capacity can be arbitrarily selected as long as it satisfies the following conditions. First, it is sufficient if the DC output voltage is maintained for, for example, 80 milliseconds or more with respect to the occurrence of an AC input instantaneous power failure, and secondly, the capacitor 14 discharges within, for example, 3 seconds after the AC input is disconnected. That is, any capacity satisfying the above conditions can be selected arbitrarily. And it is comprised so that the switch element 17 may be turned OFF when the voltage of the capacitor | condenser 14 falls. The holding time is determined by the input electrolytic capacitor 2a. As a result, when the AC input is disconnected at the time of light load, the oscillation operation of the primary control circuit 9 is quickly stopped, and the electric charge accumulated in the input electrolytic capacitor 2a of the primary side rectifying and smoothing circuit 2 is moved to the secondary side. Since no conversion is performed, the DC output can be lowered within a predetermined time. Further, when the primary control circuit 9 is activated, a current is supplied when the input is turned on via the primary control circuit activation resistor 12 connected to the anode of the capacitor 14 to start the oscillation operation of the primary control circuit 9. It is configured as follows. As a result, there is no problem that the primary control circuit 9 is restarted by the charge accumulated in the input electrolytic capacitor 2a when the input is disconnected.

以上のように、本発明のスイッチング電源装置は、交流入力切断時に従来のような１次側整流平滑回路２の入力電解コンデンサ２ａの電荷を放電させるための入力電解コンデンサ放電用抵抗８や２次側整流平滑回路６の出力電解コンデンサ６ａの電荷を放電させるための２次側ブリーダ抵抗１３を用いる必要はない。さらに、直流出力電圧を所定時間内に立ち下げることが可能になるとともに、軽負荷時の消費電力についても軽減することができるという特徴を有している。  As described above, the switching power supply device of the present invention has the input electrolytic capacitor discharge resistor 8 and the secondary for discharging the charge of the input electrolytic capacitor 2a of the primary side rectifying and smoothing circuit 2 as in the prior art when the AC input is disconnected. It is not necessary to use the secondary bleeder resistor 13 for discharging the electric charge of the output electrolytic capacitor 6a of the side rectifying and smoothing circuit 6. Further, the DC output voltage can be lowered within a predetermined time, and the power consumption at the time of light load can be reduced.

なお、本実施の形態では、１次側制御回路９の発振動作を停止するためのスイッチ素子１７としてトランジスタを用いた。しかし、これに限定されるものではなく、フォトカプラを用いても同様の効果が得られる。その場合は、抵抗１５、１６の間にこのフォトカプラのダイオード側を直列に接続し、フォトカプラのトランジスタ側にて１次制御回路９の発振動作を停止させることにより、同様の効果が得られる。  In the present embodiment, a transistor is used as the switch element 17 for stopping the oscillation operation of the primary side control circuit 9. However, the present invention is not limited to this, and the same effect can be obtained by using a photocoupler. In this case, the same effect can be obtained by connecting the diode side of the photocoupler in series between the resistors 15 and 16 and stopping the oscillation operation of the primary control circuit 9 on the transistor side of the photocoupler. .

なお、本発明は本実施の形態によって限定されるものではない。  The present invention is not limited to the present embodiment.

本発明のスイッチング電源装置は、軽負荷時の交流入力切断時の直流出力電圧を所定時間内に立ち下げることが可能で、かつ軽負荷時の消費電力を抑えることが可能である。そのためスイッチング電源装置としての適用範囲は広い。  The switching power supply apparatus of the present invention can lower the DC output voltage when the AC input is cut off at a light load within a predetermined time, and can suppress the power consumption at the time of a light load. Therefore, the application range as a switching power supply device is wide.

【書類名】明細書
【発明の名称】スイッチング電源装置
【技術分野】
【０００１】
本発明は、各種電子機器に用いられるスイッチング電源装置に関する。
【背景技術】
【０００２】
従来のスイッチング電源装置について、図２を用いて説明する。軽負荷時の交流入力切断時に直流出力電圧を所定時間内に立ち下げるために、図２に示されるように入力電解コンデンサ用放電抵抗８を用いたり、あるいは２次側ブリーダ抵抗１３を用いることが一般的であった。
【０００３】
すなわち、このスイッチング電源装置は、交流入力端子１ａ，１ｂ、１次側整流平滑回路２、スイッチングトランス３、１次巻線３ａ、バイアス用の１次制御巻線３ｂ、２次巻線３ｃ、メインスイッチング素子４、１次制御用平滑回路５、２次側整流平滑回路６、直流出力端子（陽極，陰極）７ａ，７ｂ、１次制御回路９、フォトカプラ１０、定電圧制御回路１１、１次制御回路用起動抵抗１２とを備え、１次側整流平滑回路２の陽極と陰極間に入力電解コンデンサ用放電抵抗８を接続し、直流出力端子７ａ，７ｂ間に２次側ブリーダ抵抗１３を接続している。
【０００４】
この構成により、軽負荷時の交流入力切断が生じると、１次側整流平滑回路２内に設けられた入力電解コンデンサ２ａおよび２次側整流平滑回路６の出力電解コンデンサ６ａに蓄えられている電荷が放電されるため、直流出力電圧を所定の時間内に立ち下げることができる。なお、このような構成を有するスイッチング電源装置の例が特開平２−９７２７７号公報に開示されている。
【０００５】
しかしながら、この従来の構成は、軽負荷時の交流入力切断時に直流出力電圧を所定時間内に立ち下げることは可能であるが、常時、入力電解コンデンサ用放電抵抗８や２次側ブリーダ抵抗１３が接続された構成である。その結果、電源の効率が低下するとともに、特に軽負荷時の消費電力を抑えることが困難になるという課題を有している。
【発明の開示】
【０００６】
本発明は、スイッチング電源装置の交流入力切断時に交流入力端子間の電圧レベルを検知し、所定レベル以下になった際に１次制御回路の発振動作を停止する入力電圧レベル検知回路を設けたスイッチング電源装置を提供する。
【０００７】
本発明によれば、軽負荷時の交流入力切断時に素早く１次制御回路の動作を停止させることができる。その結果、１次側整流平滑回路の入力電解コンデンサの蓄積電荷を放電させることなく、直流出力電圧を一定時間内に立ち下げることが可能になるとともに、入力電解コンデンサ用放電抵抗や２次側ブリーダ抵抗が不要になるため、軽負荷時の消費電力を大幅に軽減させることができる。
【発明の効果】
【０００８】
本発明のスイッチング電源装置は、軽負荷時の交流入力切断時の直流出力電圧を所定時間内に立ち下げることが可能で、かつ軽負荷時の消費電力を抑えることが可能である。そのためスイッチング電源装置としての適用範囲は広い。
【発明を実施するための最良の形態】
【０００９】
以下、本発明の一実施の形態について図面を用いて説明する。
【００１０】
図１に示すように本発明のスイッチング電源装置は、交流入力端子１ａ、１ｂ、１次側整流平滑回路２、スイッチングトランス３、１次巻線３ａ、バイアス用の１次制御巻線３ｂ、２次巻線３ｃ、メインスイッチング素子４、１次制御用平滑回路５、２次側整流平滑回路６、直流出力端子（陽極，陰極）７ａ，７ｂ、１次制御回路９、フォトカプラ１０、定電圧制御回路１１、１次制御回路用起動抵抗１１、コンデンサ１４、抵抗１５、１６、１次制御回路の動作を停止するためのスイッチ素子１７、ダイオード１８、入力電圧レベル検知回路１９とを備えている。そして、入力電圧レベル検知回路１９の一端を交流入力端子１ａに接続し、ダイオード１８を介してコンデンサ１４へ接続し、コンデンサ１４の陰極を交流入力端子１ｂに接続し、さらに、コンデンサ１４の両端へ抵抗１５、１６を接続し、入力電圧を分圧したものをスイッチ素子１７のベースへ供給するように構成されている。この入力電圧が所定電圧以下になるとスイッチ素子１７がＯＦＦとなる。なお、所定電圧とは、第一に交流入力瞬時停電発生に対してスイッチ素子１７が例えば８０ミリ秒以上ＯＦＦせず、第二に交流入力切断時から例えば３秒以内にスイッチ素子１７がＯＦＦする電圧である。
【００１１】
ここで、コンデンサ１４として、所定の容量を有するコンデンサを用いる。この所定の容量とは、以下の条件を満たす容量であれば任意に選択できる。第一に交流入力瞬時停電発生に対して直流出力電圧が例えば８０ミリ秒以上保持され、第二に交流入力切断時から例えば３秒以内にコンデンサ１４が放電するような容量であればよい。つまり、前記条件を満たす容量であれば任意に選定できる。そして、コンデンサ１４の電圧が低下するとスイッチ素子１７がＯＦＦとなるように構成されている。なお、上記保持時間は入力電解コンデンサ２ａにより決まるものである。その結果、軽負荷時において交流入力が切断されると、素早く１次制御回路９の発振動作が停止され、１次側整流平滑回路２の入力電解コンデンサ２ａに蓄積された電荷が２次側に変換されなくなるので、直流出力を所定時間内に立ち下げることが可能となる。また、１次制御回路９の起動に対し、コンデンサ１４の陽極に接続された１次制御回路用起動抵抗１２を介して入力投入時に電流を供給し、１次制御回路９の発振動作を開始するように構成している。その結果、入力切断時に入力電解コンデンサ２ａに蓄積されている電荷により１次制御回路９が再起動する等の不具合が発生しない。
【００１２】
以上のように、本発明のスイッチング電源装置は、交流入力切断時に従来のような１次側整流平滑回路２の入力電解コンデンサ２ａの電荷を放電させるための入力電解コンデンサ放電用抵抗８や２次側整流平滑回路６の出力電解コンデンサ６ａの電荷を放電させるための２次側ブリーダ抵抗１３を用いる必要はない。さらに、直流出力電圧を所定時間内に立ち下げることが可能になるとともに、軽負荷時の消費電力についても軽減することができるという特徴を有している。
【００１３】
なお、本実施の形態では、１次側制御回路９の発振動作を停止するためのスイッチ素子１７としてトランジスタを用いた。しかし、これに限定されるものではなく、フォトカプラを用いても同様の効果が得られる。その場合は、抵抗１５、１６の間にこのフォトカプラのダイオード側を直列に接続し、フォトカプラのトランジスタ側にて１次制御回路９の発振動作を停止させることにより、同様の効果が得られる。
【００１４】
なお、本発明は本実施の形態によって限定されるものではない。
【産業上の利用可能性】
【００１５】
本発明のスイッチング電源装置は、軽負荷時の交流入力切断時の直流出力電圧を所定時間内に立ち下げることが可能で、かつ軽負荷時の消費電力を抑えることが可能である。そのためスイッチング電源装置としての適用範囲は広い。
【図面の簡単な説明】
【００１６】
【図１】本発明のスイッチング電源装置の概略構成を示す回路図
【図２】従来のスイッチング電源装置の概略構成を示す回路図
【符号の説明】
【００１７】
１ａ，１ｂ 交流入力端子
２ １次側整流平滑回路
２ａ 入力電解コンデンサ
３ スイッチングトランス
３ａ １次巻線
３ｂ １次制御巻線
３ｃ ２次巻線
４ メインスイッチング素子
５ １次制御用平滑回路
６ ２次側整流平滑回路
６ａ 出力電解コンデンサ
７ａ，７ｂ 直流出力端子（陽極、陰極）
８ 入力電解コンデンサ用放電抵抗
９ １次制御回路
１０ フォトカプラ
１１ 定電圧制御回路
１２ １次制御回路用起動抵抗
１３ ２次側ブリーダ抵抗
１４ コンデンサ
１５，１６ 抵抗
１７ スイッチ素子
１８ ダイオード
１９ 入力電圧レベル検知回路 [Document Name] Description [Title of Invention] Switching Power Supply [Technical Field]
[0001]
The present invention relates to a switching power supply device used for various electronic devices.
[Background]
[0002]
A conventional switching power supply device will be described with reference to FIG. In order to cause the DC output voltage to fall within a predetermined time when the AC input is cut at light load, the input electrolytic capacitor discharge resistor 8 or the secondary bleeder resistor 13 may be used as shown in FIG. It was general.
[0003]
That is, this switching power supply device includes AC input terminals 1a and 1b, a primary side rectifying and smoothing circuit 2, a switching transformer 3, a primary winding 3a, a bias primary control winding 3b, a secondary winding 3c, a main Switching element 4, primary control smoothing circuit 5, secondary side rectification smoothing circuit 6, DC output terminals (anode, cathode) 7a, 7b, primary control circuit 9, photocoupler 10, constant voltage control circuit 11, primary The control circuit start resistor 12 is provided, the input electrolytic capacitor discharge resistor 8 is connected between the anode and the cathode of the primary side rectifying and smoothing circuit 2, and the secondary bleeder resistor 13 is connected between the DC output terminals 7a and 7b. is doing.
[0004]
With this configuration, when AC input disconnection occurs during light load, the charge stored in the input electrolytic capacitor 2a provided in the primary side rectifying and smoothing circuit 2 and the output electrolytic capacitor 6a of the secondary side rectifying and smoothing circuit 6 Is discharged, the DC output voltage can be lowered within a predetermined time. An example of a switching power supply device having such a configuration is disclosed in Japanese Patent Laid-Open No. 2-97277.
[0005]
However, this conventional configuration can drop the DC output voltage within a predetermined time when the AC input is cut off at a light load, but the input electrolytic capacitor discharge resistor 8 and the secondary bleeder resistor 13 are always connected. It is a connected configuration. As a result, there is a problem that the efficiency of the power source is lowered and it is difficult to suppress power consumption particularly at a light load.
DISCLOSURE OF THE INVENTION
[0006]
The present invention provides a switching circuit provided with an input voltage level detection circuit that detects a voltage level between AC input terminals when an AC input of a switching power supply device is disconnected, and stops an oscillation operation of a primary control circuit when the voltage level falls below a predetermined level. A power supply is provided.
[0007]
According to the present invention, it is possible to quickly stop the operation of the primary control circuit when the AC input is disconnected at a light load. As a result, the DC output voltage can be lowered within a predetermined time without discharging the accumulated charge of the input electrolytic capacitor of the primary side rectifying and smoothing circuit, and the input electrolytic capacitor discharge resistor and secondary side bleeder can be reduced. Since no resistor is required, power consumption at light load can be greatly reduced.
【The invention's effect】
[0008]
The switching power supply apparatus of the present invention can lower the DC output voltage when the AC input is cut off at a light load within a predetermined time, and can suppress the power consumption at the time of a light load. Therefore, the application range as a switching power supply device is wide.
BEST MODE FOR CARRYING OUT THE INVENTION
[0009]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0010]
As shown in FIG. 1, the switching power supply device of the present invention includes AC input terminals 1a, 1b, a primary side rectifying / smoothing circuit 2, a switching transformer 3, a primary winding 3a, a bias primary control winding 3b, 2 Secondary winding 3c, main switching element 4, primary control smoothing circuit 5, secondary side rectification smoothing circuit 6, DC output terminals (anode, cathode) 7a, 7b, primary control circuit 9, photocoupler 10, constant voltage The control circuit 11 includes a primary control circuit starting resistor 11, a capacitor 14, resistors 15 and 16, a switch element 17 for stopping the operation of the primary control circuit, a diode 18, and an input voltage level detection circuit 19. . Then, one end of the input voltage level detection circuit 19 is connected to the AC input terminal 1 a, connected to the capacitor 14 via the diode 18, the cathode of the capacitor 14 is connected to the AC input terminal 1 b, and further to both ends of the capacitor 14. The resistors 15 and 16 are connected, and the input voltage divided is supplied to the base of the switch element 17. When the input voltage becomes a predetermined voltage or less, the switch element 17 is turned off. The predetermined voltage means that the switch element 17 is not turned off for 80 milliseconds or more, for example, when an AC input instantaneous power failure occurs, and secondly, the switch element 17 is turned off, for example, within 3 seconds after the AC input is disconnected. Voltage.
[0011]
Here, a capacitor having a predetermined capacity is used as the capacitor 14. The predetermined capacity can be arbitrarily selected as long as it satisfies the following conditions. First, it is sufficient if the DC output voltage is maintained for, for example, 80 milliseconds or more with respect to the occurrence of an AC input instantaneous power failure, and secondly, the capacitor 14 discharges within, for example, 3 seconds after the AC input is disconnected. That is, any capacity satisfying the above conditions can be selected arbitrarily. And it is comprised so that the switch element 17 may be turned OFF when the voltage of the capacitor | condenser 14 falls. The holding time is determined by the input electrolytic capacitor 2a. As a result, when the AC input is disconnected at the time of light load, the oscillation operation of the primary control circuit 9 is quickly stopped, and the electric charge accumulated in the input electrolytic capacitor 2a of the primary side rectifying and smoothing circuit 2 is moved to the secondary side. Since no conversion is performed, the DC output can be lowered within a predetermined time. Further, when the primary control circuit 9 is activated, a current is supplied when the input is turned on via the primary control circuit activation resistor 12 connected to the anode of the capacitor 14 to start the oscillation operation of the primary control circuit 9. It is configured as follows. As a result, there is no problem that the primary control circuit 9 is restarted by the charge accumulated in the input electrolytic capacitor 2a when the input is disconnected.
[0012]
As described above, the switching power supply device of the present invention has the input electrolytic capacitor discharge resistor 8 and the secondary for discharging the charge of the input electrolytic capacitor 2a of the primary side rectifying and smoothing circuit 2 as in the prior art when the AC input is disconnected. It is not necessary to use the secondary bleeder resistor 13 for discharging the electric charge of the output electrolytic capacitor 6a of the side rectifying and smoothing circuit 6. Further, the DC output voltage can be lowered within a predetermined time, and the power consumption at the time of light load can be reduced.
[0013]
In the present embodiment, a transistor is used as the switch element 17 for stopping the oscillation operation of the primary side control circuit 9. However, the present invention is not limited to this, and the same effect can be obtained by using a photocoupler. In this case, the same effect can be obtained by connecting the diode side of the photocoupler in series between the resistors 15 and 16 and stopping the oscillation operation of the primary control circuit 9 on the transistor side of the photocoupler. .
[0014]
The present invention is not limited to the present embodiment.
[Industrial applicability]
[0015]
The switching power supply apparatus of the present invention can lower the DC output voltage when the AC input is cut off at a light load within a predetermined time, and can suppress the power consumption at the time of a light load. Therefore, the application range as a switching power supply device is wide.
[Brief description of the drawings]
[0016]
FIG. 1 is a circuit diagram showing a schematic configuration of a switching power supply apparatus according to the present invention. FIG. 2 is a circuit diagram showing a schematic configuration of a conventional switching power supply apparatus.
[0017]
1a, 1b AC input terminal 2 Primary side rectification smoothing circuit 2a Input electrolytic capacitor 3 Switching transformer 3a Primary winding 3b Primary control winding 3c Secondary winding 4 Main switching element 5 Primary control smoothing circuit 6 Secondary Side rectification smoothing circuit 6a Output electrolytic capacitor 7a, 7b DC output terminal (anode, cathode)
8 Input Electrolytic Capacitor Discharge Resistor 9 Primary Control Circuit 10 Photocoupler 11 Constant Voltage Control Circuit 12 Primary Control Circuit Startup Resistor 13 Secondary Side Bleeder Resistor 14 Capacitor 15, 16 Resistor 17 Switch Element 18 Diode 19 Input Voltage Level Detection circuit

Claims (3)

スイッチングトランスを介して、交流入力を直流出力に変換するスイッチング電源装置であって、少なくとも１次側に１次側整流平滑回路と１次制御回路と１次制御用平滑回路とスイッチング素子とを有するとともに、２次側に２次側整流平滑回路と定電圧制御回路とを有し、１次側に入力電圧が所定電圧以下になると前記１次制御回路の発振動作を停止させるための入力電圧レベル検知回路を設けたことを特徴とするスイッチング電源装置。A switching power supply device that converts an alternating current input into a direct current output via a switching transformer, having at least a primary side rectifying and smoothing circuit, a primary control circuit, a primary control smoothing circuit, and a switching element on at least the primary side An input voltage level for stopping the oscillation operation of the primary control circuit when the secondary side has a secondary side rectifying / smoothing circuit and a constant voltage control circuit on the secondary side and the input voltage falls below a predetermined voltage on the primary side. A switching power supply comprising a detection circuit. 前記入力電圧レベル検知回路は、その一端が交流入力端子の一方に接続されるとともにダイオードを介してコンデンサの陽極側に接続され、その他端が前記交流入力端子の他方に接続されるとともに前記コンデンサの陰極側に接続され、さらに前記コンデンサの両端に分圧抵抗が接続され、前記分圧抵抗により入力電圧が分圧されたものがスイッチ素子のベースに供給されるように構成され、前記コンデンサは所定の容量を有し、前記入力電圧が所定電圧以下になると前記スイッチ素子がＯＦＦするように構成されていることを特徴とする請求項１記載のスイッチング電源装置。The input voltage level detection circuit has one end connected to one of the AC input terminals and connected to the anode side of the capacitor via a diode, and the other end connected to the other of the AC input terminals and the other end of the capacitor. A voltage dividing resistor is connected to the cathode side, and a voltage dividing resistor is connected to both ends of the capacitor, and an input voltage divided by the voltage dividing resistor is supplied to the base of the switch element. 2. The switching power supply device according to claim 1, wherein the switching element is turned off when the input voltage becomes equal to or lower than a predetermined voltage. 前記スイッチ素子は、トランジスタとフォトカプラのうちのいずれか一つである請求項２記載のスイッチング電源装置。The switching power supply device according to claim 2, wherein the switch element is one of a transistor and a photocoupler.
JP2006510919A 2004-03-17 2005-03-03 Switching power supply Pending JPWO2005088819A1 (en)

Applications Claiming Priority (3)

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