外文翻譯---開關(guān)模式電源

1、<p><b>　　外文文獻(xiàn)</b></p><p>　　Switched-mode power supply</p><p>　　A switched-mode power supply (also switching-mode power supply, SMPS, or simply switcher) is an electronic power s

2、upply unit (PSU) that incorporates a switching regulator. While a linear regulator maintains the desired output voltage by dissipating excess power in a pass power transistor, the switched-mode power supply switches a po

3、wer transistor between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. It switches at a much-</p><p>　　The main advantage of this meth

4、od is greater efficiency because the switching transistor dissipates little power in the saturated state and the off state compared to the semiconducting state (active region). Other advantages include smaller size and l

5、ighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high amplitude,

6、high frequency energy that th</p><p>　　A note about terminology</p><p>　　Although the term "power supply" has been in use since radios were first powered from the line/mains, that does

7、 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 commercial AC power and provides one or more DC outputs. It would be more correctly referre

8、d to as a power converter, but long usage has established the term.</p><p>　　Classification</p><p>　　SMPS can be classified into four types according to the input and output waveforms:</p>

9、<p>　　AC in, DC out: rectifier, off-line converter input stage </p><p>　　DC in, DC out: voltage converter, or current converter, or DC to DC converter </p><p>　　AC in, AC out: frequency c

10、hanger, cycloconverter, transformer </p><p>　　DC in, AC out: inverter</p><p>　　Input rectifier stage</p><p>　　If the SMPS has an AC input, then the first stage is to convert the inp

11、ut 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 o

12、peration 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</p>

13、<p>　　If an input range switch is used, the rectifier stage is usually configured to operate as a voltage doubler when operating on the low voltage (~120 VAC) range and as a straight rectifier when operating on the

14、 high voltage (~240 VAC) range. If an input range switch is not used, then a full-wave rectifier is usually used and the downstream inverter stage is simply designed to be flexible enough to accept the wide range of dc v

15、oltages that will be produced by the rectifier stage. In higher-power SM</p><p>　　Inverter stage</p><p>　　The inverter stage converts DC, whether directly from the input or from the rectifier st

16、age described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be a

17、bove 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve hig</p><p>　　Volta

18、ge converter and output rectifier</p><p>　　If the output is required to be isolated from the input, as is usually the case in mains power supplies, the inverted AC is used to drive the primary winding of a h

19、igh-frequency transformer. This converts the voltage up or down to the required output level on its secondary winding. The output transformer in the block diagram serves this purpose.</p><p>　　If a DC output

20、 is required, the AC output from the transformer is rectified. For output voltages above ten volts or so, ordinary silicon diodes are commonly used. For lower voltages, Schottky diodes are commonly used as the rectifier

21、elements; they have the advantages of faster recovery times than silicon diodes (allowing low-loss operation at higher frequencies) and a lower voltage drop when conducting. For even lower output voltages, MOSFETs may be

22、 used as synchronous rectifiers; compared to S</p><p>　　The rectified output is then smoothed by a filter consisting of inductors and capacitors. For higher switching frequencies, components with lower capac

23、itance and inductance are needed.</p><p>　　Simpler, non-isolated power supplies contain an inductor instead of a transformer. This type includes boost converters, buck converters, and the so called buck-boos

24、t converters. These belong to the simplest class of single input, single output converters which utilize one inductor and one active switch. The buck converter reduces the input voltage in direct proportion to the ratio

25、of conductive time to the total switching period, called the duty cycle. For example an ideal buck converter with a </p><p>　　Other types of SMPSs use a capacitor-diode voltage multiplier instead of inductor

26、s and transformers. These are mostly used for generating high voltages at low currents (Cockcroft-Walton generator). The low voltage variant is called charge pump.</p><p>　　Regulation</p><p>　　A

27、 feedback circuit monitors the output voltage and compares it with a reference voltage, which is set manually or electronically to the desired output. If there is an error in the output voltage, the feedback circuit comp

28、ensates by adjusting the timing with which the MOSFETs are switched on and off. This part of the power supply is called the switching regulator. The Chopper controller shown in the block diagram serves this purpose. Depe

29、nding on design/safety requirements, the controller may or </p><p>　　Open-loop regulators do not have a feedback circuit. Instead, they rely on feeding a constant voltage to the input of the transformer or i

30、nductor, and assume that the output will be correct. Regulated designs compensate for the parasitic capacitance of the transformer or coil. Monopolar designs also compensate for the magnetic hysteresis of the core.</p

31、><p>　　The feedback circuit needs power to run before it can generate power, so an additional non-switching power-supply for stand-by is added.</p><p>　　Transformer design</p><p>　　SMP

32、S transformers run at high frequency. Most of the cost savings (and space savings) in off-line power supplies come from the fact that a high frequency transformer is much smaller than the 50/60 Hz transformers formerly u

33、sed.</p><p>　　There are several differences in the design of transformers for 50 Hz vs 500 kHz. Firstly a low frequency transformer usually transfers energy through its core (soft iron), while the (usually f

34、errite) core of a high frequency transformer limits leakage. Since the waveforms in a SMPS are generally high speed (PWM square waves), the wiring must be capable of supporting high harmonics of the base frequency due to

35、 the skin effect, which is a major source of power loss.</p><p>　　Power factor</p><p>　　Simple off-line switched mode power supplies incorporate a simple full wave rectifier connected to a large

36、 energy storing capacitor. Such SMPSs draw current from the AC line in short pulses when the mains instantaneous voltage exceeds the voltage across this capacitor. During the remaining portion of the AC cycle the capacit

37、or provides energy to the power supply.</p><p>　　As a result, the input current of such basic switched mode power supplies has high harmonic content and relatively low power factor. This creates extra load o

38、n utility lines, increases heating of the utility transformers and standard AC electric motors, and may cause stability problems in some applications such as in emergency generator systems or aircraft generators. Harmoni

39、cs can be removed through the use of filter banks but the filtering is expensive, and the power utility may require a busi</p><p>　　In 2001 the European Union put into effect the standard IEC/EN61000-3-2 to

40、set limits on the harmonics of the AC input current up to the 40th harmonic for equipment above 75 W. The standard defines four classes of equipment depending on its type and current waveform. The most rigorous limits (c

41、lass D) are established for personal computers, computer monitors, and TV receivers. In order to comply with these requirements modern switched-mode power supplies normally include an additional power fact</p><

42、;p>　　Putting a current regulated boost chopper stage after the off-line rectifier (to charge the storage capacitor) can help correct the power factor, but increases the complexity (and cost).</p><p>　　Qua

43、siresonant ZCS/ZVS</p><p>　　A quasiresonant ZCS/ZVS switch (Zero Current/Zero Voltage) is a design where "each switch cycle delivers a quantized 'packet' of energy to the converter output, and

44、switch turn-on and turn-off occurs at zero current and voltage, resulting in an essentially lossless switch."</p><p>　　Efficiency</p><p>　　Higher input voltage and synchronous rectification

45、 mode makes the conversion process more efficient. Higher switch frequency allows component size to be shrunk, but suffer from radio frequency (RF) properties on the other hand. The power consumption of the controller al

46、so has to be taken into account.</p><p>　　Applications</p><p>　　Switched-mode PSUs in domestic products such as personal computers often have universal inputs, meaning that they can accept power

47、 from most mains supplies throughout the world, with rated frequencies from 50 Hz to 60 Hz and voltages from 100 V to 240 V (although a manual voltage range switch may be required). In practice they will operate from a m

48、uch wider frequency range and often from a DC supply as well. In 2006, at an Intel Developers Forum, Google engineers proposed the use of a single 12 </p><p>　　Most modern desktop and laptop computers alread

49、y have a DC-DC converter on the motherboard, to step down the voltage from the PSU or the battery to the CPU core voltage, as low as 0.8 V for a low voltage CPU to 1.2-1.5 V for a desktop CPU as of 2007. Most laptop comp

50、uters also have a DC-AC inverter to step up the voltage from the battery to drive the backlight, typically around 1000 Vrms.</p><p>　　Certain applications, such as in automobile industry where ordinary cars

51、often use 12 V DC and in some industrial settings, DC supply is chosen to avoid hum and interference and ease the integration of capacitors and batteries used to buffer the voltage. Most small aircraft use 28 V DC, but l

52、arger aircraft like Boeing-747 often use up to 90 kVA 3-phase at 200 V AC 400 Hz, though they often have a DC bus as well. Even fighter planes like F-16 use 400 Hz power. The MD-81 airplane has an 115/200 V </p>&

53、lt;p>　　See also: Avionics, Airplane ground support</p><p>　　In the case of TV sets, for example, one can test the excellent regulation of the power supply by using a variac. For example, in some models ma

54、de by Philips, the power supply starts when the voltage reaches around 90 volts. From there, one can change the voltage with the variac, and go as low as 40 volts and as high as 260 (known such case that voltage was 360)

55、, and the image will show absolutely no alterations.</p><p>　　Terminology</p><p>　　The term switchmode was widely used until Motorola trademarked SWITCHMODE(TM), for products aimed at the switch

56、ing-mode power supply market, and started to enforce their trademark.</p><p><b>　　外文翻譯</b></p><p><b>　　開關(guān)模式電源</b></p><p>　　開關(guān)模式電源（也開關(guān)式電源，開關(guān)電源，或只是交換機(jī)）是一種電子電源供

57、應(yīng)器（電源），包含了開關(guān)穩(wěn)壓器。雖然線性穩(wěn)壓保持理想的輸出電壓超過電源的耗散在通過功率晶體管的開關(guān)模式電源開關(guān)功率晶體管飽和度之間，并斷開（完全關(guān)閉），可變占空比是其平均理想的輸出電壓。它的開關(guān)在一個(gè)非常高的頻率（幾十甚至幾百千赫）比交流的頻率要高，相當(dāng)于變壓器，可充當(dāng)遠(yuǎn)距離傳輸電源。創(chuàng)建一個(gè)矩形開關(guān)波形，通常涉及到的主要的變壓器;通常幾個(gè)二級(jí)整流器，一系列電感、電容和濾波提供各種直流輸出低紋波。</p><p>

58、;　　主要利用這一方法提高效率，因?yàn)殚_關(guān)晶體管功耗小、功率大，半導(dǎo)體為關(guān)閉狀態(tài)（有源區(qū)）。其他優(yōu)勢(shì)包括更小的尺寸和較輕的重量（從消除低頻變壓器具有高體重）和低熱量的產(chǎn)生，還有更高的效率。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。 </p><p><b>　　有關(guān)術(shù)語(yǔ)的說明</b></p>

59、;<p>　　雖然“電源一詞”開始出現(xiàn)于無線電的供電線路/主干線，這并不意味著它是力量的源泉，而是作為一個(gè)電池提供電源。這是一個(gè)這直接由公網(wǎng)交流供電，提供一個(gè)或多個(gè)直流輸出的設(shè)備。更確切地可將其稱為電源轉(zhuǎn)換器，但可長(zhǎng)時(shí)間不間斷使用。</p><p>　　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(jí) 直流——直流：電壓轉(zhuǎn)換器，或電流轉(zhuǎn)換器，或直流對(duì)直流

60、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(gè)開關(guān)電源AC輸入，然后在第一階段把交流變成直流輸出。這就是所謂的整流。整流電路可配置一個(gè)電壓倍增，增加了一個(gè)開關(guān)操作手動(dòng)或自動(dòng)。這是一個(gè)較大的特點(diǎn)，這類產(chǎn)品允許用電范圍從120V到240V。整流器產(chǎn)生穩(wěn)壓直流電壓，然后通過一個(gè)大型濾波電容器。目前從電源的這一整流電路中出現(xiàn)的短脈沖交流電壓峰值來看。這些脈沖產(chǎn)生重大的高頻能量，從而降

61、低了功率因數(shù)。特別控制技術(shù)可以采用下列開關(guān)電源，以迫使平均輸入電流跟蹤正弦形狀的交流輸入電壓，因此，設(shè)計(jì)師應(yīng)設(shè)法糾正功率因數(shù)。一個(gè)開關(guān)電源與DC輸入并不需要這個(gè)階段。一個(gè)開關(guān)電源設(shè)計(jì)的AC輸入然后變?yōu)橹绷鞴╇姡▽?30V交流變?yōu)?30V直流） ，直流經(jīng)過整流階段不變。這是可取的協(xié)商，但該手冊(cè)在嘗試此動(dòng)作，盡管大多數(shù)供應(yīng)是有相當(dāng)?shù)哪芰Φ炔僮鳎词箾]有提到的文件中。然而，這種類型的使用可能有害整流階段，因?yàn)樗荒?lt;/p>&l

62、t;p><b>　　逆變階段</b></p><p>　　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(gè)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 ） 。頻率通常選擇將超過20千赫，使人們察覺不到。輸出電壓是光耦合輸入，從而可以非常嚴(yán)格的控制。開關(guān)是實(shí)施一個(gè)多倍放大能力（以實(shí)現(xiàn)高增益）的MOSFET。 MOSFET的是一種有低導(dǎo)通、高

63、電流能力的晶體管。因?yàn)橹挥凶詈笠粋€(gè)階段有一個(gè)大的占空比，可在前幾個(gè)階段實(shí)施雙極晶體管導(dǎo)致大致相同的效率。第二個(gè)最后階段需要一個(gè)相輔相成的設(shè)計(jì)，在一個(gè)晶體管后接一個(gè)相同的MOSFET和一個(gè)放電MOSFET的。設(shè)計(jì)使用一個(gè)電阻可以運(yùn)行大部分的空閑時(shí)間，降低效率。所有早期階段不能達(dá)到很好的效率，因?yàn)槊恳粋€(gè)階段功耗都會(huì)降低了10倍，從而早期階段負(fù)責(zé)最多產(chǎn)生1％的效率。</p><p>　　電壓轉(zhuǎn)換器和輸出整流器 <

64、/p><p>　　如果輸出要與輸入分開，常常作為工作電路提供主電源。逆變交流是用來驅(qū)動(dòng)主要繞組的高頻變壓器。這種轉(zhuǎn)換的電壓上升或下降到所需的輸出電平可在其二次繞組。</p><p>　　如果需要輸出直流，糾正變壓器輸出的交流。輸出電壓為10伏或10V以上的話，常用普通硅二極管。對(duì)于較低的電壓，肖特基二極管時(shí)常用的整流元件;它的優(yōu)勢(shì)，恢復(fù)時(shí)間比硅二極管更快（允許低損耗運(yùn)行在更高的頻率）和可以在電

65、壓下降時(shí)進(jìn)行。甚至輸出電壓更低的MOSFET可作為同步整流器;與肖特基二極管相比，它們可將電壓控制在較低范圍。 </p><p>　　經(jīng)過整流后的電壓輸出較平滑，然后通過一個(gè)電感器和電容器組成的過濾器。對(duì)于更高的開關(guān)頻率，較低的電容和電感元件是必要的。 </p><p>　　簡(jiǎn)單的說，非隔離式電源包含一個(gè)電感，而不是變壓器。這種類型的電源包括升壓轉(zhuǎn)換器，降壓轉(zhuǎn)換器，以及所謂的升壓轉(zhuǎn)換器。這

66、些屬于最簡(jiǎn)單的一類單輸入，單輸出轉(zhuǎn)換器，它利用一個(gè)電感器和一個(gè)有效的開關(guān)。降低的降壓轉(zhuǎn)換器的輸入電壓的比率傳導(dǎo)時(shí)間與總開關(guān)期間成正比，這就是所謂的占空比。例如，一個(gè)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。反饋控制回路是用來調(diào)節(jié)輸出電壓，通過改變占空比來彌補(bǔ)投入的變化電壓。輸出電壓的升壓轉(zhuǎn)換器總是大于輸入電壓的升壓輸出電壓反轉(zhuǎn)，但可能大于，等于或小于其規(guī)模輸入電壓。這一類的轉(zhuǎn)換器有許多的變化和擴(kuò)展，

67、但是這三種形式都是基于幾乎所有的隔離和非隔離式DC直流轉(zhuǎn)換器。通過增加第二個(gè)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)。</p><p>　　其他類型的開關(guān)模式電源是使用電容二極管電壓倍增而不是電感器和變壓器。這些都是主要用于產(chǎn)生高電壓低電流（克羅夫特-沃爾頓發(fā)電機(jī)）。低電壓變異被稱為電荷泵。</p><p><b>　　條例 </b&

68、gt;</p><p>　　監(jiān)測(cè)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(dòng)的或電子的輸出。如果有一個(gè)錯(cuò)誤的輸出電壓，反饋電路補(bǔ)償調(diào)整的時(shí)機(jī)與該MOSFET的是接通或關(guān)斷。這部分的電力供應(yīng)被稱為開關(guān)穩(wěn)壓器。根據(jù)安全設(shè)計(jì)的要求，控制器可能不會(huì)只包含一個(gè)孤立的隔離機(jī)制（如光耦合器）直流輸出。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。 </p><p>　　開環(huán)

69、監(jiān)管沒有反饋電路。相反，他們依賴于持續(xù)恒定電壓和輸入變壓器或電感，并承擔(dān)的輸出將會(huì)是正弦的。設(shè)計(jì)調(diào)節(jié)補(bǔ)償寄生電容的變壓器或線圈。單極設(shè)計(jì)也彌補(bǔ)磁滯回的核心。 </p><p>　　反饋電路需求的運(yùn)行功率，然后才可以發(fā)電，從而增加非開關(guān)電源。</p><p><b>　　變壓器設(shè)計(jì) </b></p><p>　　開關(guān)電源變壓器的運(yùn)行在高頻率。大部

70、分的線性電源成本節(jié)?。ㄓ止?jié)省空間）在來自這樣一個(gè)事實(shí)，即高頻變壓器使用的頻率是遠(yuǎn)小于50/60赫茲。 </p><p>　　有幾個(gè)不同的設(shè)計(jì)，變壓器50赫茲與500千赫。首先低頻變壓器傳輸能量通常通過其核心（軟鐵） ，而（通常鐵氧體）核心的高頻變壓器限制泄漏。由于一個(gè)開關(guān)電源波形在一般高速（脈寬調(diào)制方波），線路必須能夠支持高次諧波的基頻由于集膚效應(yīng)，這是一個(gè)功率損耗的主要來源，。</p><p

71、><b>　　功率因數(shù) </b></p><p>　　簡(jiǎn)單線性開關(guān)式電源納入一個(gè)簡(jiǎn)單的全波整流電路連接到一個(gè)大型能源儲(chǔ)存電容器。這種開關(guān)電源目前來自AC線短脈沖的瞬時(shí)電壓超過電源電壓在此電容。在余下的部分交流周期電容器提供能源的電力供應(yīng)。 </p><p>　　最后，輸入電流等基本開關(guān)式電源的高次諧波含量和相對(duì)較低的功率因數(shù)。這造成額外的負(fù)荷效用線，增加暖氣的實(shí)

72、用變壓器和標(biāo)準(zhǔn)交流電動(dòng)機(jī)，并可能引起的穩(wěn)定性問題在一些應(yīng)用，如在應(yīng)急發(fā)電機(jī)系統(tǒng)或飛機(jī)的發(fā)電機(jī)。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(gè)非常低的功率因數(shù)，以購(gòu)買和安裝過濾現(xiàn)場(chǎng)。 </p><p>　　在2001年歐洲聯(lián)盟實(shí)施的標(biāo)準(zhǔn)IEC/EN61000-3-2設(shè)限的諧波的交流輸入電流諧波的第40次以上的設(shè)備75美國(guó)標(biāo)準(zhǔn)的定義四類設(shè)備根據(jù)其類型和電流波形。最嚴(yán)格的限制（ D類）都建立了個(gè)

73、人電腦，電腦顯示器，電視接收器。為了符合這些要求的現(xiàn)代開關(guān)模式電源供應(yīng)器通常包括一個(gè)額外的功率因數(shù)校正（ PFC ）的階段。 </p><p>　　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(chǔ)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） 。</p><p>　　Quasiresonant諧振/開關(guān) </p><p>　　一個(gè)諧振/零電壓開關(guān)（零電流/

74、零電壓）是一種設(shè)計(jì)的“每個(gè)開關(guān)周期提供了一個(gè)量化'包'的能量轉(zhuǎn)換器輸出，并切換開啟和關(guān)閉發(fā)生在零電流和電壓，導(dǎo)致基本上無損開關(guān)。 “ </p><p><b>　　效率 </b></p><p>　　較高的輸入電壓在同步整流模式轉(zhuǎn)換過程中更有效率。較高開關(guān)頻率允許元件尺寸縮小，但遭受的射頻（ RF ）性能另一方面。耗電量的控制器也必須加以考慮。<

75、/p><p><b>　　應(yīng)用 </b></p><p>　　開關(guān)模式電源的產(chǎn)品在國(guó)內(nèi)也有很多應(yīng)用，如將它們大量應(yīng)用與個(gè)人電腦中，這意味著它們可以適用于世界各地的電路中，額定頻率從50赫茲到60赫茲，電壓從100伏至240伏（雖然可能需要手動(dòng)調(diào)節(jié)開關(guān)電壓范圍）。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。2006年，在英特爾開發(fā)商論壇，谷歌工程師建

76、議使用一個(gè)單一的12 V電源在PC ，高效率的開關(guān)模式用品直接在PCB上。 </p><p>　　最現(xiàn)代化的臺(tái)式和筆記本電腦已經(jīng)有一個(gè)DC-DC轉(zhuǎn)換器在主板上，電壓從電源或電池送往核心CPU，CPU的最低電壓為0.8 V，到2007年臺(tái)式電腦的CPU電壓在1.2~1.5之間。大多數(shù)筆記本電腦也有一架DC - AC變換器加緊電壓由電池來驅(qū)動(dòng)背光，通常約1000 Vrms 。 </p><p>

77、;　　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。大多數(shù)小飛機(jī)使用28伏直流電，但大型飛機(jī)像波音747通常使用了90千伏安3相200 V交流400赫茲，但他們往往有一個(gè)直流母線以及。即使像戰(zhàn)斗機(jī)F - 16型使用400 Hz電源。于MD - 81飛機(jī)有二百分之一百一十五交流V 400赫茲和28 V直流電源系統(tǒng)產(chǎn)生的3個(gè)40千伏安交流

78、發(fā)電機(jī)。直升機(jī)還使用28伏直流電系統(tǒng)。一些潛艇像蘇聯(lián)阿爾法級(jí)潛艇利用兩個(gè)同步發(fā)電機(jī)提供一個(gè)變量三相電流， 2 × 1500千瓦， 400伏， 400赫茲。航天飛機(jī)使用的燃料電池發(fā)電3 30 - 36伏直流電。有些被轉(zhuǎn)換成400赫茲交流電源和28 V直流電源。在國(guó)際空間站使用120伏直流電源。大卡車使用24伏直流電。 </p><p>　　另見：航空電子設(shè)備，飛機(jī)地面支持 </p><

79、p>　　如電視機(jī)，例如，一個(gè)可以測(cè)試的出色調(diào)節(jié)電源使用variac 。例如，在一些模型所作的飛利浦，電源啟動(dòng)時(shí)，電壓達(dá)到90伏特。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(duì)沒有任何改變。</p><p><b>　　術(shù)語(yǔ) </b></p><p>　　開關(guān)模式這個(gè)詞開始作為術(shù)語(yǔ)應(yīng)用