JP3620551B2

JP3620551B2 - Uninterruptible power system

Info

Publication number: JP3620551B2
Application number: JP28216695A
Authority: JP
Inventors: 誠坂根
Original assignee: Yuasa Corp
Current assignee: Yuasa Corp
Priority date: 1995-10-30
Filing date: 1995-10-30
Publication date: 2005-02-16
Anticipated expiration: 2015-10-30
Also published as: JPH09130993A

Description

【０００１】
【発明の属する技術分野】
本発明は無停電電源装置に関するもので、さらに詳しく言えば、商用電源の停電時に、蓄電池からの直流電力を昇圧してインバータに供給する昇圧回路を備えた無停電ラインを有する無停電電源装置に関するものである。
【０００２】
【従来の技術】
無停電電源装置は、常時は商用電源からの交流電力を直送ラインを介して直接負荷に供給し、停電時は蓄電池からの直流電力を交流電力に変換するインバータを有する無停電ラインを介して前記負荷に供給するようにしたもので、停電による負荷のトラブルを防止するためのものである。
【０００３】
このような無停電電源装置に用いられる蓄電池は、無停電ラインの出力に１００Ｖを得ようとした場合、その放電終止電圧が１７０Ｖ以上になるように設計する必要があり、蓄電池を多数直列に接続するのに代えて蓄電池の直流電圧を昇圧する昇圧回路を設けて低コスト化、軽量化を図ったものが多用されるようになってきている。
【０００４】
上記した昇圧回路を設けた従来の無停電電源装置は図３に示したようなもので、商用電源１からの交流電力が入力されて蓄電池の充電電力を出力する充電器２、この充電器２からの充電電力によって充電される蓄電池３、この蓄電池３からの直流電力を昇圧する昇圧回路４、この昇圧回路４によって昇圧された直流電力を交流電力に変換するインバータ５およびこのインバータ５からの交流出力を波形整形するフィルタ６からなる無停電ライン１０と、前記商用電源１からの交流電力を直接出力する直送ライン２０とを有し、前記無停電ライン１０と直送ライン２０とが切替スイッチ３０によって相互に切り替えられるようにしたものである。
【０００５】
そして、前記昇圧回路４は蓄電池３の端子間に接続されたチョークコイル４１およびスイッチング素子４２の直列接続回路と、前記スイッチング素子４２に並列に接続されたダイオード４３、第１コンデンサ４４−１および第２コンデンサ４４−２の直列接続回路とからなり、前記インバータ５は前記ダイオード４３と前記第１コンデンサ４４−１との接続点と、前記第２コンデンサ４４−２と前記スイッチング素子４２との接続点との間に接続された第１スイッチング素子５１−１、第２スイッチング素子５１−２の直列接続回路からなり、前記フィルタ６は前記第１スイッチング素子５１−１と前記第２スイッチング素子５１−２との接続点と、前記第１コンデンサ４４−１と前記第２コンデンサ４４−２との接続点との間に接続されたフィルタリアクトル６１、フィルタコンデンサ６２の直列接続回路からなる。
【０００６】
次に、上記した従来の無停電電源装置の動作を図４により説明する。
【０００７】
図４に示した如く、昇圧回路４のスイッチング素子４２は商用電源１の周波数より高い周波数で、昇圧回路４の出力電圧がインバータ５の入力電圧として適当な値になるようなパルス幅でオン、オフさせ、インバータ５の第１スイッチング素子５１−１、第２スイッチング素子５１−２は商用電源１の１周期ごとに、商用電源１の周波数より高い周波数で、その波高値に比例したパルス幅で交互にオン、オフさせてフィルタ６のフィルタコンデンサ６２の端子間に商用電源１の周波数と同じ周波数の正弦波を出力させる。
【０００８】
すなわち、昇圧回路４のスイッチング素子４２がオンの場合は、蓄電池３→チョークコイル４１→スイッチング素子４２→蓄電池３なる経路▲１▼に電流が流れてチョークコイル４１にエネルギーを蓄積し、昇圧回路４のスイッチング素子４２がオフの場合は、蓄電池３→チョークコイル４１→ダイオード４３→第１コンデンサ４４−１→第２コンデンサ４４−２→蓄電池３なる経路▲２▼に電流が流れて第１コンデンサ４４−１、第２コンデンサ４４−２を充電する。
【０００９】
そして、インバータ５の第１スイッチング素子５１−１がオン、第２スイッチング素子５１−２がオフで、第１スイッチング素子５１−１のオンデューテイが５０％以上の場合は、前記経路▲１▼、▲２▼に電流が流れるとともに、第１コンデンサ４４−１→第１スイッチング素子５１−１→フィルタリアクトル６１→フィルタコンデンサ６２→第１コンデンサ４４−１なる経路▲３▼に電流が流れて第１コンデンサ４４−１が放電し、インバータ５の第１スイッチング素子５１−１がオフ、第２スイッチング素子５１−２がオンの場合は、前記経路▲１▼、▲２▼に電流が流れるとともに、フィルタリアクトル６１→フィルタコンデンサ６２→第２コンデンサ４４−２→第２スイッチング素子５１−２の寄生ダイオード→フィルタリアクトル６１なる経路▲４▼に電流が流れてフィルタコンデンサ６２の端子間に正の半サイクルが出力される。
【００１０】
また、インバータ５の第１スイッチング素子５１−１がオフ、第２スイッチング素子５１−２がオンで、第１スイッチング素子５１−１のオンデューテイが５０％以下の場合は、前記経路▲１▼、▲２▼に電流が流れるとともに、第２コンデンサ４４−２→フィルタコンデンサ６２→フィルタリアクトル６１→第２スイッチング素子５１−２→第２コンデンサ４４−２なる経路▲５▼に電流が流れて第２コンデンサ４４−２が放電し、インバータ５の第１スイッチング素子５１−１がオン、第２スイッチング素子５１−２がオフの場合は、前記経路▲１▼、▲２▼に電流が流れるとともに、フィルタリアクトル６１→第１スイッチング素子５１−１の寄生ダイオード→第１コンデンサ４４−１→フィルタコンデンサ６２→フィルタリアクトル６１なる経路▲６▼に電流が流れてフィルタコンデンサ６２の端子間に負の半サイクルが出力される。
【００１１】
【発明が解決しようとする課題】
上記した動作により、蓄電池３の直流電圧を昇圧してインバータ５に供給することはできるが、無停電ラインの出力に１００Ｖを得ようとすると、第１コンデンサ４４−１と第２コンデンサ４４−２との直列接続回路に約３４０Ｖの直流電圧が印加されることになり、昇圧回路４のスイッチング素子４２の耐圧およびインバータ５の第１スイッチング素子５１−１、第２スイッチング素子５１−２の耐圧を４００Ｖ級以上のものにしなければならず、それによってコストが上昇するという問題があった。
【００１２】
【課題を解決するための手段】
上記課題を解決するため、本発明は、商用電源からの交流電力が入力されて蓄電池の充電電力を出力する充電器、この充電器からの充電電力によって充電される蓄電池、この蓄電池からの直流電力を昇圧する昇圧回路、この昇圧回路によって昇圧された直流電力を交流電力に変換するインバータおよびこのインバータからの交流出力を波形整形するフィルタからなる無停電ラインと、前記商用電源からの交流電力を直接出力する直送ラインとを有するとともに、前記無停電ラインと直送ラインとを相互に切り替える切替スイッチを有する無停電電源装置において、前記昇圧回路は前記蓄電池の端子間に接続された２組のスイッチング素子の直列接続回路と、直列接続点が前記第１組のスイッチング素子の直列接続点に接続された第１、第２のコンデンサの直列接続回路と、直列接続点が前記第２組のスイッチング素子の直列接続点に接続された第１、第２のダイオードの直列接続回路とからなり、かつ前記第１、第２のコンデンサの直列接続回路と前記第１、第２のダイオードの直列接続回路が並列に接続されてなり、前記インバータは前記第１、第２のコンデンサの直列接続回路および前記第１、第２のダイオードの直列接続回路と並列に接続された、第１、第２のスイッチング素子の直列接続回路からなり、前記フィルタは前記第１、第２のスイッチング素子の直列接続点と前記第１、第２のダイオードの直列接続点との間に接続された、フィルタリアクトルとフィルタコンデンサとの直列接続回路からなることを特徴とするものである。
【００１３】
【発明の実施の形態】
以下、本発明をその実施の形態に基づいて説明する。
【００１４】
図１は本発明の無停電電源装置の実施の形態を示す回路図で、図３と同じ機能を有する部分には同じ符号を付している。
【００１５】
本発明の特徴は、図１に示した如く、昇圧回路４を、蓄電池３の端子間に接続された第１組のスイッチング素子４２Ａ−１，４２Ａ−２の直列接続回路４２Ａと第２組のスイッチング素子４２Ｂ−１，４２Ｂ−２の直列接続回路４２Ｂと、直列接続点が前記第１組のスイッチング素子４２Ａ−１，４２Ａ−２の直列接続点に接続された第１、第２のコンデンサ４４−１，４４−２の直列接続回路と、直列接続点が前記第２組のスイッチング素子４２Ｂ−１，４２Ｂ−２の直列接続点に接続された第１、第２のダイオード４３−１，４３−２の直列接続回路とからなるようにするとともに、かつ前記第１、第２のコンデンサ４４−１，４４−２の直列接続回路と前記第１、第２のダイオード４３−１，４３−２の直列接続回路が並列に接続されてなるようにし、インバータ５を、前記第１、第２のコンデンサ４４−１，４４−２の直列接続回路および前記第１、第２のダイオード４３−１，４３−２の直列接続回路と並列に接続された、第１、第２のスイッチング素子の直列接続回路とし、フィルタ６を、前記第１、第２のスイッチング素子の直列接続点と前記第１、第２のダイオード４３−１，４３−２の直列接続点との間に接続された、フィルタリアクトル６１とフィルタコンデンサ６２との直列接続回路としたものである。
【００１６】
次に、上記した本発明の無停電電源装置の動作を図２により説明する。
【００１７】
図２に示した如く、昇圧回路４の第１組のスイッチング素子４２Ａ−１，４２Ａ−２と第２組のスイッチング素子４２Ｂ−１，４２Ｂ−２とは、商用電源１の周波数と同じ周波数でスイッチング素子４２Ａ−１，４２Ｂ−２とスイッチング素子４２Ａ−２，４２Ｂ−１とをそれぞれ同時にオン、オフさせ、インバータ５の第１スイッチング素子５１−１、第２スイッチング素子５１−２は商用電源１の半周期ごとにその周波数より高い周波数で、その波高値に比例したパルス幅で交互にオン、オフさせるようにし、前記昇圧回路４のスイッチング素子４２Ａ−１，４２Ｂ−２をオンさせた時にインバータ５の第１スイッチング素子５１−１をオン、オフさせ、第２スイッチング素子５１−２をオフさせてフィルタ６のフィルタコンデンサ６２の端子間に正の半サイクルを出力させ、前記昇圧回路４のスイッチング素子４２Ａ−２，４２Ｂ−１をオンさせた時にインバータ５の第１スイッチング素子５１−１をオフ、第２スイッチング素子５１−２をオン、オフさせてフィルタ６のフィルタコンデンサ６２の端子間に負の半サイクルを出力させる。
【００１８】
すなわち、昇圧回路４のスイッチング素子４２Ａ−１，４２Ｂ−２をオン、スイッチング素子４２Ａ−２，４２Ｂ−１をオフさせておき、インバータ５の第１スイッチング素子５１−１がオン、第２スイッチング素子５１−２がオフの場合は、蓄電池３→スイッチング素子４２Ａ−１→第２コンデンサ４４−２→第２ダイオード４３−２→スイッチング素子４２Ｂ−２→蓄電池３なる経路（１）と、第１コンデンサ４４−１→第１スイッチング素子５１−１→フィルタリアクトル６１→フィルタコンデンサ６２→スイッチング素子４２Ｂ−２→蓄電池３→スイッチング素子４２Ａ−１→第１コンデンサ４４−１なる経路（２）とに電流が流れて第１コンデンサ４４−１が放電し、第２コンデンサ４４−２が充電されてフィルタリアクトル６１とフィルタコンデンサ６２との直列接続回路に第１コンデンサ４４−１の端子間電圧と蓄電池３の電圧の和が印加され、昇圧回路４のスイッチング素子４２Ａ−１，４２Ｂ−２をオン、スイッチング素子４２Ａ−２，４２Ｂ−１をオフさせておき、インバータ５の第１スイッチング素子５１−１、第２スイッチング素子５１−２がオフの場合は、上記経路（１）と、フィルタリアクトル６１→フィルタコンデンサ６２→スイッチング素子４２Ｂ−２→蓄電池３→スイッチング素子４２Ａ−１→第２コンデンサ４４−２→第２スイッチング素子５１−２の寄生ダイオード→フィルタリアクトル６１なる経路（３）とに電流が流れてフィルタリアクトル６１とフィルタコンデンサ６２との直列接続回路に印加される電圧は０になり、第１スイッチング素子５１−１、第２スイッチング素子５１−２のオン、オフ比を商用電源１の電圧の波高値に比例させるように制御すると、フィルタコンデンサ６２の端子間に正の半サイクルを出力させることができる。
【００１９】
また、昇圧回路４のスイッチング素子４２Ａ−１，４２Ｂ−２をオフ、スイッチング素子４２Ａ−２，４２Ｂ−１をオンさせておき、インバータ５の第１スイッチング５１−１がオフ、第２スイッチング素子５１−２がオンの場合は、蓄電池３→スイッチング素子４２Ｂ−１→第１ダイオード４３−１→第１コンデンサ４４−１→スイッチング素子４２Ａ−２→蓄電池３なる経路（４）と、第２コンデンサ４４−２→スイッチング素子４２Ａ−２→蓄電池３→スイッチング素子４２Ｂ−１→フィルタコンデンサ６２→フィルタリアクトル６１→第２スイッチング素子５１−２→第２コンデンサ４４−２なる経路（５）とに電流が流れて第２コンデンサ４４−２が放電し、第１コンデンサ４４−１が充電されてフィルタリアクトル６１とフィルタコンデンサ６２との直列接続回路に第２コンデンサ４４−２の端子間電圧と蓄電池３の電圧の和が印加され、昇圧回路４のスイッチング素子４２Ａ−１，４２Ｂ−２をオフ、スイッチング素子４２Ａ−２，４２Ｂ−１をオンさせておき、インバータ５の第１スイッチング素子５１−１、第２スイッチング素子５１−２がオフの場合は、上記経路（４）と、フィルタリアクトル６１→第１スイッチング素子５１−１の寄生ダイオード→第１コンデンサ４４−１→スイッチング素子４２Ａ−２→蓄電池３→スイッチング素子４２Ｂ−１→フィルタコンデンサ６２なる経路（６）とに電流が流れてフィルタリアクトル６１とフィルタコンデンサ６２との直列接続回路に印加される電圧は０になり、第１スイッチング素子５１−１、第２スイッチング素子５１−２のオン、オフ比を商用電源１の電圧の波高値に比例させるように制御すると、フィルタコンデンサ６２の端子間に負の半サイクルを出力させることができる。
【００２０】
上記した動作により、フィルタコンデンサ６２の端子間に正の半サイクルが出力される場合は、スイッチング素子４２Ａ−１のオンによって第１コンデンサ４４−１の負極側の電位が蓄電池３の直流電圧まで上昇するため、第２スイッチング素子５１−２には蓄電池３の直流電圧の２倍の電圧が印加され、フィルタコンデンサ６２の端子間に負の半サイクルが出力される場合は、スイッチング素子４２Ｂ−１のオンによって第２コンデンサ４４−２の正極側の電位に蓄電池３の直流電圧が加算されるため、第１スイッチング素子５１−１には蓄電池３の直流電圧の２倍の電圧が印加される。
【００２１】
従って、無停電ラインの出力に１００Ｖを得ようとすると、第１コンデンサ４４−１と第２コンデンサ４４−２との直列接続回路に約１７０Ｖの直流電圧が印加されるように蓄電池３の直流電圧を定めればよく、昇圧回路４のスイッチング素子４２Ａ−１，４２Ａ−２，４２Ｂ−１，４２Ｂ−２およびインバータ５の第１スイッチング素子５１−１、第２スイッチング素子５１−２の耐圧も２００Ｖ級のもので対応することができる。
【００２２】
【発明の効果】
上記した如く、本発明は、無停電電源装置の蓄電池の直流電圧を低くすることができるとともに、昇圧回路およびインバータに用いるスイッチング素子に高耐圧のものを用いなくてもよいので、さらに無停電電源装置の低コスト化、軽量化を図ることができる。
【図面の簡単な説明】
【図１】本発明の無停電電源装置の回路図である。
【図２】本発明の無停電電源装置の各部の動作波形図である。
【図３】従来の無停電電源装置の回路図である。
【図４】従来の無停電電源装置の各部の動作波形図である。
【符号の説明】
１商用電源
２充電器
３蓄電池
４昇圧回路
５インバータ
６フィルタ
１０無停電ライン
２０直送ライン
３０切替スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an uninterruptible power supply, and more specifically, relates to an uninterruptible power supply having an uninterruptible line including a booster circuit that boosts DC power from a storage battery and supplies it to an inverter when a commercial power supply fails. Is.
[0002]
[Prior art]
The uninterruptible power supply always supplies AC power from a commercial power source directly to a load via a direct transmission line, and at the time of a power outage, the uninterruptible power supply unit converts the DC power from a storage battery into AC power via the uninterruptible line. It is intended to be supplied to the load in order to prevent a load trouble caused by a power failure.
[0003]
The storage battery used in such an uninterruptible power supply must be designed so that the end-of-discharge voltage is 170 V or higher when trying to obtain 100 V for the output of the uninterruptible line, and many storage batteries are connected in series. Instead of this, a booster circuit that boosts the DC voltage of the storage battery to reduce the cost and weight has been widely used.
[0004]
The conventional uninterruptible power supply device provided with the booster circuit as shown in FIG. 3 is a charger 2 that receives AC power from the commercial power source 1 and outputs the charging power of the storage battery, and this charger 2. Storage battery 3 charged with charging power from the battery, a booster circuit 4 that boosts DC power from the battery 3, an inverter 5 that converts DC power boosted by the booster circuit 4 into AC power, and an AC from the inverter 5 There is an uninterruptible line 10 comprising a filter 6 for waveform shaping of the output and a direct transmission line 20 for directly outputting AC power from the commercial power supply 1, and the uninterruptible line 10 and the direct transmission line 20 are switched by a changeover switch 30. It can be switched between each other.
[0005]
The booster circuit 4 includes a series connection circuit of a choke coil 41 and a switching element 42 connected between terminals of the storage battery 3, a diode 43, a first capacitor 44-1 and a first capacitor 44-1 connected in parallel to the switching element 42. The inverter 5 includes a connection point between the diode 43 and the first capacitor 44-1, and a connection point between the second capacitor 44-2 and the switching element 42. The first switching element 51-1 and the second switching element 51-2 are connected in series, and the filter 6 includes the first switching element 51-1 and the second switching element 51-2. And a connection point between the first capacitor 44-1 and the second capacitor 44-2. I filter reactor 61 comprises a serial connection circuit of the filter capacitor 62.
[0006]
Next, the operation of the above conventional uninterruptible power supply will be described with reference to FIG.
[0007]
As shown in FIG. 4, the switching element 42 of the booster circuit 4 is turned on at a frequency higher than the frequency of the commercial power supply 1 and with a pulse width such that the output voltage of the booster circuit 4 becomes an appropriate value as the input voltage of the inverter 5. The first switching element 51-1 and the second switching element 51-2 of the inverter 5 are turned off at a frequency higher than the frequency of the commercial power source 1 for each cycle of the commercial power source 1 and with a pulse width proportional to the peak value. By alternately turning on and off, a sine wave having the same frequency as that of the commercial power supply 1 is output between the terminals of the filter capacitor 62 of the filter 6.
[0008]
That is, when the switching element 42 of the booster circuit 4 is on, current flows through the path {circle around (1)} of the storage battery 3 → the choke coil 41 → the switching element 42 → the storage battery 3 to accumulate energy in the choke coil 41. When the switching element 42 is off, a current flows through the path (2) of the storage battery 3 → the choke coil 41 → the diode 43 → the first capacitor 44-1 → the second capacitor 44-2 → the storage battery 3 and the first capacitor 44 −1, the second capacitor 44-2 is charged.
[0009]
When the first switching element 51-1 of the inverter 5 is on, the second switching element 51-2 is off, and the on-duty of the first switching element 51-1 is 50% or more, the path (1), 2), current flows through the first capacitor 44-1, the first switching element 51-1, the filter reactor 61, the filter capacitor 62, and the first capacitor 44-1. When 44-1 is discharged, the first switching element 51-1 of the inverter 5 is turned off, and the second switching element 51-2 is turned on, a current flows through the paths (1) and (2), and a filter reactor. 61 → filter capacitor 62 → second capacitor 44-2 → parasitic diode of second switching element 51-2 → filter react 61 becomes the path ▲ 4 ▼ current flows in the positive half cycle is outputted between the terminals of the filter capacitor 62.
[0010]
Further, when the first switching element 51-1 of the inverter 5 is off, the second switching element 51-2 is on, and the on-duty of the first switching element 51-1 is 50% or less, the path (1), ▲ 2), current flows through the second capacitor 44-2 → filter capacitor 62 → filter reactor 61 → second switching element 51-2 → second capacitor 44-2, so that current flows through the second capacitor 44-2. When 44-2 is discharged, the first switching element 51-1 of the inverter 5 is turned on, and the second switching element 51-2 is turned off, a current flows through the paths (1) and (2) and a filter reactor. 61 → parasitic diode of first switching element 51-1 → first capacitor 44-1 → filter capacitor 62 → filter reactor Negative half cycle is outputted between the terminals of the filter capacitor 62 current flows through the 1 consisting path ▲ 6 ▼.
[0011]
[Problems to be solved by the invention]
With the above-described operation, the DC voltage of the storage battery 3 can be boosted and supplied to the inverter 5, but when trying to obtain 100 V for the output of the uninterruptible line, the first capacitor 44-1 and the second capacitor 44-2 A DC voltage of about 340 V is applied to the series connection circuit with the voltage of the switching element 42 of the booster circuit 4 and the withstand voltages of the first switching element 51-1 and the second switching element 51-2 of the inverter 5. There was a problem that it had to be 400V class or higher, thereby increasing the cost.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a charger that receives AC power from a commercial power source and outputs charging power of the storage battery, a storage battery that is charged by the charging power from the charger, and DC power from the storage battery. An uninterruptible line comprising a booster circuit for boosting the voltage, an inverter for converting the DC power boosted by the booster circuit to AC power, and a filter for shaping the AC output from the inverter, and the AC power from the commercial power supply directly In the uninterruptible power supply apparatus having a direct transmission line for outputting and a changeover switch for switching the uninterruptible line and the direct transmission line to each other, the booster circuit includes two sets of switching elements connected between terminals of the storage battery. A series connection circuit, and first and second series connection points connected to a series connection point of the first set of switching elements. A series connection circuit of capacitors, and a series connection circuit of first and second diodes, the series connection point of which is connected to the series connection point of the second set of switching elements, and the first and second capacitors. And a series connection circuit of the first and second diodes are connected in parallel, and the inverter includes a series connection circuit of the first and second capacitors and the first and second diodes. The filter comprises a series connection circuit of first and second switching elements connected in parallel with a series connection circuit, and the filter includes a series connection point of the first and second switching elements and the first and second diodes. It is characterized by comprising a series connection circuit of a filter reactor and a filter capacitor connected between the series connection points.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiments.
[0014]
FIG. 1 is a circuit diagram showing an embodiment of the uninterruptible power supply apparatus according to the present invention, and parts having the same functions as those in FIG.
[0015]
The feature of the present invention is that, as shown in FIG. 1, the booster circuit 4 is connected to the series connection circuit 42A of the first set of switching elements 42A-1 and 42A-2 connected between the terminals of the storage battery 3 and the second set. The series connection circuit 42B of the switching elements 42B-1 and 42B-2, and the first and second capacitors 44 whose series connection point is connected to the series connection point of the first set of switching elements 42A-1 and 42A-2. -1, 44-2 series connection circuit, and first and second diodes 43-1 and 43 whose series connection point is connected to the series connection point of the second set of switching elements 42B-1 and 42B-2. -2 series connection circuit, and the series connection circuit of the first and second capacitors 44-1 and 44-2 and the first and second diodes 43-1 and 43-2. Are connected in parallel. Thus, the inverter 5 is connected in parallel with the series connection circuit of the first and second capacitors 44-1 and 44-2 and the series connection circuit of the first and second diodes 43-1 and 43-2. The first and second switching elements are connected in series, and the filter 6 is connected to the first and second switching elements in series and the first and second diodes 43-1 and 43-. A series connection circuit of a filter reactor 61 and a filter capacitor 62 connected between two series connection points.
[0016]
Next, the operation of the uninterruptible power supply of the present invention will be described with reference to FIG.
[0017]
As shown in FIG. 2, the first set of switching elements 42 A- 1 and 42 A- 2 and the second set of switching elements 42 B- 1 and 42 B- 2 of the booster circuit 4 have the same frequency as that of the commercial power supply 1. The switching elements 42A-1, 42B-2 and the switching elements 42A-2, 42B-1 are simultaneously turned on and off, respectively, and the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are commercial power sources 1 When the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned on, the inverters are alternately turned on and off at a frequency higher than that frequency every half cycle and with a pulse width proportional to the peak value. The first switching element 51-1 is turned on and off, the second switching element 51-2 is turned off, and the filter capacitor 62 of the filter 6 is turned on. When a positive half cycle is output between the terminals and the switching elements 42A-2 and 42B-1 of the booster circuit 4 are turned on, the first switching element 51-1 of the inverter 5 is turned off, and the second switching element 51-2 Is turned on and off to output a negative half cycle between the terminals of the filter capacitor 62 of the filter 6.
[0018]
That is, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned on, the switching elements 42A-2 and 42B-1 are turned off, the first switching element 51-1 of the inverter 5 is turned on, and the second switching element When 51-2 is off, the path (1) of the storage battery 3 → the switching element 42A-1 → the second capacitor 44-2 → the second diode 43-2 → the switching element 42B-2 → the storage battery 3 and the first capacitor 44-1 → first switching element 51-1 → filter reactor 61 → filter capacitor 62 → switching element 42B-2 → storage battery 3 → switching element 42A-1 → path (2) consisting of the first capacitor 44-1 The first capacitor 44-1 is discharged, the second capacitor 44-2 is charged, and the filter reactor 61 is charged. The sum of the voltage between the terminals of the first capacitor 44-1 and the voltage of the storage battery 3 is applied to the series connection circuit with the filter capacitor 62, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned on, and the switching element 42A- 2, 42B-1 is turned off, and when the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are off, the path (1) and the filter reactor 61 → filter capacitor 62 → A current flows through the path (3) of the switching element 42B-2 → the storage battery 3 → the switching element 42A-1 → the second capacitor 44-2 → the parasitic diode of the second switching element 51-2 → the filter reactor 61 and the filter reactor 61 The voltage applied to the series connection circuit of the filter capacitor 62 becomes 0, and the first switch When the ON / OFF ratio of the switching element 51-1 and the second switching element 51-2 is controlled to be proportional to the peak value of the voltage of the commercial power supply 1, a positive half cycle is output between the terminals of the filter capacitor 62. Can do.
[0019]
Further, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned off, the switching elements 42A-2 and 42B-1 are turned on, the first switching 51-1 of the inverter 5 is turned off, and the second switching element 51 is turned on. -2 is on, the path (4) of the storage battery 3 → the switching element 42B-1 → the first diode 43-1 → the first capacitor 44-1 → the switching element 42A-2 → the storage battery 3 and the second capacitor 44 −2 → switching element 42A-2 → storage battery 3 → switching element 42B-1 → filter capacitor 62 → filter reactor 61 → second switching element 51-2 → second capacitor 44-2, current flows through the path (5). The second capacitor 44-2 is discharged, the first capacitor 44-1 is charged, and the filter reactor 61 and the filter are filled. The sum of the voltage between the terminals of the second capacitor 44-2 and the voltage of the storage battery 3 is applied to the series connection circuit with the capacitor 62, the switching elements 42A-1 and 42B-2 of the booster circuit 4 are turned off, and the switching element 42A-2 , 42B-1 are turned on, and when the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are off, the path (4) and the filter reactor 61 → the first switching element 51 -1 parasitic diode → first capacitor 44-1 → switching element 42 A- 2 → storage battery 3 → switching element 42 B- 1 → filter capacitor 62, a current flows to filter reactor 61 and filter capacitor 62. The voltage applied to the series connection circuit is 0, and the first switching element 51-1, the second switching element On the element 51-2 and controls to proportional off ratio peak value of the voltage of the commercial power source 1, it is possible to output a negative half-cycle between the terminals of the filter capacitor 62.
[0020]
When a positive half cycle is output between the terminals of the filter capacitor 62 by the above-described operation, the potential on the negative electrode side of the first capacitor 44-1 rises to the DC voltage of the storage battery 3 by turning on the switching element 42A-1. Therefore, when a voltage that is twice the DC voltage of the storage battery 3 is applied to the second switching element 51-2 and a negative half cycle is output between the terminals of the filter capacitor 62, the switching element 42B-1 Since the DC voltage of the storage battery 3 is added to the potential on the positive electrode side of the second capacitor 44-2 when turned on, a voltage twice as high as the DC voltage of the storage battery 3 is applied to the first switching element 51-1.
[0021]
Therefore, when trying to obtain 100V in the output of the uninterruptible line, the DC voltage of the storage battery 3 is applied so that a DC voltage of about 170V is applied to the series connection circuit of the first capacitor 44-1 and the second capacitor 44-2. The withstand voltage of the switching elements 42A-1, 42A-2, 42B-1, 42B-2 of the booster circuit 4 and the first switching element 51-1 and the second switching element 51-2 of the inverter 5 are also 200V. It is possible to respond with the thing of the grade.
[0022]
【The invention's effect】
As described above, the present invention can reduce the DC voltage of the storage battery of the uninterruptible power supply, and does not need to use a high withstand voltage switching element used in the booster circuit and the inverter. The cost and weight of the device can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an uninterruptible power supply according to the present invention.
FIG. 2 is an operation waveform diagram of each part of the uninterruptible power supply according to the present invention.
FIG. 3 is a circuit diagram of a conventional uninterruptible power supply.
FIG. 4 is an operation waveform diagram of each part of a conventional uninterruptible power supply.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Charger 3 Storage battery 4 Booster circuit 5 Inverter 6 Filter 10 Uninterruptible line 20 Direct transmission line 30 Changeover switch

Claims

A charger that receives AC power from a commercial power source and outputs the charging power of the storage battery, a storage battery that is charged by the charging power from the charger, a booster circuit that boosts DC power from the storage battery, and a booster that boosts the voltage An uninterruptible line composed of an inverter that converts the DC power into AC power and a filter that shapes the AC output from the inverter, and a direct transmission line that directly outputs the AC power from the commercial power source. in the uninterruptible power supply having a switching switch for switching the power failure line and direct line with each other, said booster circuit being connected between the terminals of the storage battery, on the frequency of the commercial power source, first and second sets to off The switching element series connection circuit and the series connection point are connected to the series connection point of the first set of switching elements. First, a series connection circuit of the second capacitor, the first consists of a series circuit of a second diode series connection point is connected to a series connection point of the second set of switching elements, and said A series connection circuit of first and second capacitors and a series connection circuit of the first and second diodes are connected in parallel, and the inverter includes the series connection circuit of the first and second capacitors and the first connection circuit. 1. A series connection circuit of first and second switching elements connected in parallel with a series connection circuit of second diodes and turned on and off at a frequency higher than the frequency of a commercial power supply. A series connection circuit of a filter reactor and a filter capacitor connected between the series connection point of the second switching element and the series connection point of the first and second diodes. Uninterruptible power supply, characterized in that.