基于sg3525設(shè)計(jì)單相正弦波spwm逆變電源外文翻譯-預(yù)覽頁
【正文】 or so, ordinary silicon diodes are monly used. For lower voltages, Schottky diodes are monly used as the rectifier elements。 typically several secondaries feed rectifiers, series inductors, and filter capacitors to provide various DC outputs with low ripple.The main advantage of this method is greater efficiency because the switching transistor dissipates little power in the saturated state and the off state pared to the semiconducting state (active region). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater plexity, the generation of high amplitude, high frequency energy that the lowpass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.A note about terminologyAlthough the term power supply has been in use since radios were first powered from the line/mains, that does not mean that it is a source of power, in the sense that a battery provides power. It is simply a device that (usually) accepts mercial AC power and provides one or more DC outputs. It would be more correctly referred to as a power converter, but long usage has established the term.ClassificationSMPS can be classified into four types according to the input and output waveforms:AC in, DC out: rectifier, offline converter input stage DC in, DC out: voltage converter, or current converter, or DC to DC converter AC in, AC out: frequency changer, cycloconverter, transformer DC in, AC out: inverterInput rectifier stageIf the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 volt or 240 volt supplies. The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. Special control techniques can be employed by the following SMPS to force the average input current to follow the sinusoidal shape of the AC input voltage thus the designer should try correcting the power factor. An SMPS with a DC input does not require this stage. An SMPS designed for AC input can often be run from a DC supply (for 230V AC this would be 330V DC), as the DC passes through the rectifier stage unchanged. It39。packet39。創(chuàng)建一個矩形開關(guān)波形，通常涉及到的主要的變壓器。缺點(diǎn)包括更大的復(fù)雜性，產(chǎn)生高振幅，高頻率能量，必須加低通濾波器，以避免電磁干擾 （ EMI ）之類，和紋波電壓的開關(guān)頻率和諧波頻率不足。分類 開關(guān)電源可分為四種類型根據(jù)輸入和輸出波形： 交流——直流：整流器，離線轉(zhuǎn)換器輸入級 直流——直流：電壓轉(zhuǎn)換器，或電流轉(zhuǎn)換器，或直流對直流轉(zhuǎn)換器 交流——交流：變頻器，變頻，變壓 直流——交流：逆變器 輸入整流器階段 如果有一個開關(guān)電源AC輸入，然后在第一階段把交流變成直流輸出。整流器產(chǎn)生穩(wěn)壓直流電壓，然后通過一個大型濾波電容器。一個開關(guān)電源與DC輸入并不需要這個階段。這可能導(dǎo)致器件過熱，并導(dǎo)致電源受到損害。逆變階段逆變直流轉(zhuǎn)換階段，無論是直接輸入或從整流階段輸入，要變?yōu)榻涣餍枰ㄟ^一個電源振蕩器，其輸出變壓器有很少的繞組，頻率為幾十或幾百千赫（ kHz ） 。 MOSFET的是一種有低導(dǎo)通、高電流能力的晶體管。所有早期階段不能達(dá)到很好的效率，因?yàn)槊恳粋€階段功耗都會降低了10倍，從而早期階段負(fù)責(zé)最多產(chǎn)生1％的效率。如果需要輸出直流，糾正變壓器輸出的交流。甚至輸出電壓更低的MOSFET可作為同步整流器。 簡單的說，非隔離式電源包含一個電感，而不是變壓器。例如，一個理想的降壓轉(zhuǎn)換器與輸入為10 V運(yùn)行在50 ％占空比，將產(chǎn)生平均輸出為5V電壓。通過增加第二個電感的CUK和SEPIC整流器，或者通過增加額外的積極開關(guān)，各種橋變換器可以實(shí)現(xiàn)。條例 監(jiān)測反饋電路的輸出電壓，并與它的參考電壓相比較，期望設(shè)置手動的或電子的輸出。電腦，電視機(jī)和錄像機(jī)用品的開關(guān)電源中的光耦合器嚴(yán)格控制輸出電壓。單極設(shè)計(jì)也彌補(bǔ)磁滯回的核心。 有幾個不同的設(shè)計(jì)，變壓器50赫茲與500千赫。這種開關(guān)電源目前來自AC線短脈沖的瞬時電壓超過電源電壓在此電容。諧波可以刪除通過使用濾波器的過濾，但非常昂貴，以及電力企業(yè)可能需要一個非常低的功率因數(shù)，以購買和安裝過濾現(xiàn)場。 把目前的監(jiān)管提高階段后，直升機(jī)離線整流器（收取存儲電容器）可幫助正確的功率因數(shù)，但增加了復(fù)雜性（和成本） 。 “ 效率 較高的輸入電壓在同步整流模式轉(zhuǎn)換過程中更有效率。他們將在實(shí)踐中適用于更廣泛的頻率范圍，而且往往也可以由直流電源供電。 某些應(yīng)用程序，如在汽車行業(yè)，普通汽車經(jīng)常使用12伏直流電，在某些工業(yè)環(huán)境中，直流電源選擇，以避免哼聲和干涉和易用性的一體化電容器和電池用來緩沖的電壓。直升機(jī)還使用28伏直流電系統(tǒng)。在國際空間站使用120伏直流電源。從那里，人們可以改變電壓的variac ，并前往低至40伏特，高260 （稱為這種情況下，電壓為360 ） ，圖像將顯示絕對沒有
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