外文翻譯=高壓靜電發(fā)生器=3700字符

1 High Voltage Power Supplies for Electrostatic Applications Cliff Scapellati, Vice President of Engineering Abstract High voltage power supplies are a key component in electrostatic applications. A variety of industrial and scientific applications of high voltage power supplies are presented for the scientist, engineer, specifier and user of electrostatics. Industrial processes, for example, require significant monitoring of operational conditions in order to maximize product output, improve quality, and reduce cost. New advances in power supply technology provide higher levels of monitoring and process control. Scientific experiments can also be influenced by power supply effects. output accuracy, stability, ripple and regulation are discussed.Contributing effects such as output accuracy, stability, ripple and regulation are discussed. I.Introduction The use of high voltage in scientific and industrial applications is commonplace. In particular, electrostatics can be utilized for a variety of effects. Broadly stated, electrostatics is the study of effects produced by electrical charges or fields. The applications of electrostatics can be used to generate motion of a material without physical contact, to separate materials down to the elemental level, to combine materials to form a homogeneous mixture and other practical and scientific uses. By definition, the ability of electrostatic effects to do work requires a difference in electrical potential between two or more materials. In most cases, the energy required to force a potential difference is derived from a high voltage source. This high voltage source can be a high voltage power supply. Todays high voltage power supplies are solid state, high frequency designs, which provide performance and control unattainable only a few years ago. Significant improvements in reliability, stability, control, size reductions, cost and safety have been achieved. By being made aware of these improvements, the user of high voltage power supplies for electrostatic applications can benefit. Additionally, unique requirements of high voltage power supplies should be understood as they can affect the equipment, experiments, process or product they are used in. II.Operational Principles of High Voltage Power Supplies 2 A simplified schematic diagram of a high voltage power supply is shown in Fig.1.The input voltage source may have a wide range of voltage characteristics. AC sources of 50Hz to 400Hz at 100 megOhms are common. (This is to reduce power dissipation in the circuit and reduce the effects of temperature change due to self heating). The large resistance and the high voltage rating requires unique technology specific to high voltage resistors. The unique high voltage resistor must be paired with a low value resistor to insure ratio tracking under changes of temperature, voltage, humidity and time. In addition, the high value of resistance in the feedback network means a susceptibility to very low current interference. It can be seen that currents as low as 1 X 10-9 amps will result in 100ppm errors. Therefore, corona current effects must seriously be considered in the design of the resistor and the resistor feedback network. Also, since much of the resistor technology is based on a ceramic core or substrate, piezoelectric effects must also be considered. It can be demonstrated that vibrating a high voltage power supply during operation will impose a signal, related to the vibration frequency, on the output of the power supply. IV. Auxiliary Functions Involves With the High Voltage Power Supply In many applications of high voltage, additional control functions may be required for the instrument. The power supply designer must be as familiar with the electrostatics application as the end user. By understanding the application, the power supply designer can incorporate important functions to benefit the end process. A typical feature that can be implemented into a high voltage power supply is an ARC Sense control. Fig. 3 shows a schematic diagram of an arc sense circuit. Typically, a current sensing device such as a current transformer or resistor is inserted in the low voltage side of the high voltage output circuits. 6 Typically, the arc currents are equal to: I = (E/R)(1) where I = Arc current in amperes. E = Voltage present at high voltage capacitor. R = Output limiting resistor in ohms. The arc current is usually much greater than the normal dc current rating of the power supply. This is due to keeping the limiting resistance to a minimum, and thereby the power dissipation to a minimum. Once the arc event is sensed, a number of functions can be implemented. Arc Quench is a term which defines the characteristic of an arc to terminate when the applied voltage is removed.Fig. 4 shown a block diagram of an arc quench feature. If shutdown is not desired on the first arc event, a digital counter can be added as shown in Fig.5.Shutdown or quench will occur after a predetermined number of arcs have been sensed. A reset time must be used so low frequency arc events are not accumulated in the counter. Example: A specification may define an arc shutdown if eight arcs are sensed within a one minute interval. A useful application of the arc sense circuit is to maximize the applied voltage, 7 just below the arcing level. This can be accomplished by sensing that an arc has occurred and lowering the voltage a small fraction until arcing ceases. Voltage can be increased automatically at a slow rate.(Fig. 6) Another feature which can be found in the high voltage power supply is a highly accurate current monitor circuit. For generic applications this monitor feature may only be accurate to milliamperes, or microamperes. However, in some electrostatic applications accuracy down to femtoamperes may be required. This accuracy can be provided by the high voltage monitoring circuits. However, the user of the power supply usually must specify this requirement before ordering. V. Generating Constant Current Sources In many electrostatic applications, a constant current created by corona effects is desirable. This can be accomplished in a number of unique ways. A constant current source can be broadly defined as having a source impedance much larger than the load impedance it is supplying. Schematically it can be shown as in Fig. 7: Practically stated, as R2 changes impedance there is negligible effect on the current through R1. Therefore, R1 and R2 have a constant current. In a single power 8 supply application, this can be accomplished two ways. The first is to provide an external resistor as the current regulating device. The second is to electronically regulate the current using the current feedback control as shown in Fig. 2. In applications where multiple current sources are required, it may not be practical to have multiple power supplies. In this case, multiple resistors can be used to provide an array of current sources. This is typically used where large areas need to be processed with the use of electrostatics. Fig. 8 shows this scheme. VI. Conclusion This paper presented information useful to electrostatic applications using high voltage power supplies. The high voltage power supply has concerns which differentiate it from conventional power supplies. The designer of high voltage power supplies can be a key resource for the user of electrostatics. Significant control features can be offered by the high voltage power supply. In addition, safety aspects of high voltage use requires important attention. High voltage sources can be lethal. The novice user of high voltage should be educated on the dangers involved. A general guideline for safety practices is found in IEEE standard 510-1983 Recommended Practices for Safety in High Voltages and High Power Testing 4. References: 1 C. Scapellati, High Voltage Power Supplies for Analytical Instrumentation, Pittsburgh Conference, March 1995. 2 D. Chambers and C. Scapellati , How to Specify Todays High Voltage Power 9 Supplies, Electronic Products Magazine, March 1994. 3D. Chambers and C. Scapellati, New High Frequency, High Voltage Power Supplies for Microwave Heating Applications, Proceedings of the 29th Microwave Power Symposium, July 1994. 4IEEE Standard 510-1983, IEEE Recommended Practices for Safety In High Voltage and High Power Testing. 高壓靜電 發(fā)生器 Cliff Scapellati， 工程副總裁 摘要 高壓電源的關鍵組成部分 是 靜電應用。各種工業(yè)和科學應用的高電壓電源以供科學家，工程師，規(guī)范和用戶的靜電。工業(yè)生產(chǎn)過程，例如，需要大量的監(jiān)測作業(yè)條件，以便最大限度地擴大產(chǎn)品產(chǎn)量，改善品質，并降低成本。新進展供電技術提供更高水平的監(jiān)測和過程控制?？茖W實驗還可以影響電力的影響。促進效果，如輸出精度，穩(wěn)定，紋波和管理進行了討論。 一。導言 使用高電壓的科學及工業(yè)應用是司空見慣。特別是，靜電可用于不同 的影響。從廣義上說，是研究靜電效應所產(chǎn)生的電氣費或領域。靜電的應用可用于產(chǎn)生運動的材料，無需身體接觸，分離材料到元素水平，結合材料，形成均勻的混合物和其他實際和科學用途。根據(jù)定義，靜電的能力的影響，需要做的工作不同電位兩個或兩個以上的材料。在大多數(shù)情況下，所需的能量，迫使?jié)撛诘膮^(qū)別是來自高壓電源。這種高電壓源可以是一個高壓電源 應用 。今天的高電壓電源器是固態(tài)，高頻設計，提供性能和控制無法實現(xiàn)的僅在幾年前。顯著提高的可靠性，穩(wěn)定性，控制，減少大小，成本和安全已經(jīng)實現(xiàn)。通過了解這些改進，用戶的高壓靜電電源的應用中 受益。此外， 作為 獨特的要求，高壓電源 發(fā)生 器應被理解為他們可以影響到設備，實驗，過程或產(chǎn)品 。 二。 高 壓電源 發(fā)生 器 的操作原理 圖 1 一種簡化的高壓電源 10 一種簡化 的 高壓電源 如 圖 1。輸入電壓的來源可能有廣泛的電壓特性。交流 電 源 50至 400Hz在 24V到 480V是常見的。直 流電源從 5V至 300V也可以找到。關鍵是用戶要了解輸入電壓的要求，因為這會影響整個系統(tǒng)的使用和設計。監(jiān)管機構，如美國保險商實驗室，加拿大標準協(xié)會，國際電工技術委員會及其他具有高度參與任何電路連接到電網(wǎng)。除了主要的逆變電源電路的電源， 輸入電壓源也可以用于輔助電源控制電路和其他輔助電源要求。 輸入 濾波平臺 提供輸入電壓源。這種調節(jié)通常的形式，整頓和過濾交流渠道，并附加的濾波直流來源。超載保護， EMI， EMC 和監(jiān)控電路也可以找到。輸出輸入的過濾器通常是直流電壓源。這個直流電壓提供了能量來源逆變。逆變階段的直流電源轉換為高頻交流信號。電 源中 存在許多不同的逆變器拓撲結構。高壓電源器具有獨特的因素，可能會決 定逆變器的最佳辦法。該逆變器產(chǎn)生高頻交流信號是加緊了高壓變壓器的原因，高頻產(chǎn)生是為了提供高性能與縮小規(guī)模和減少磁存儲電容器的紋波。 一個變壓器 具有 高加強 比例 時， 高變頻器 就會被加倍 。加強高比率反映了一種寄生電容在 主要的高電壓互感器， 這反映為（ Nsec： Npri）第二 功能。這 種 大 的 寄生電容出現(xiàn)在主要的變壓器必須是隔離的逆變器開關設備。如果沒有， 異 常高脈沖電流將 會 出 現(xiàn) 在逆變器 之中 。 常見的高電壓電源 的另一個參數(shù) 是一種廣泛的負荷運作。由于存在高電壓，絕緣擊穿是司空見慣。該逆變器的 穩(wěn)定 性和控制回路的特點，必須 負責 幾乎 與 任何開路，短路和業(yè)務負載相結合的條件。這些問題以及可靠性和成本，必須在高壓電源逆變器拓撲結構 之中 解決。 高頻逆變器輸出的是適用于 主要 高電壓升壓變 壓器。適當?shù)母唠妷鹤儔浩鞯脑O計需要大量的理論和實際工程。了解 這個有吸引力的 設計必須 應用材料和過程控制。許多具體的專門知識 涉及大量的二級輪流， 較高的次級 電壓。由于這些因素，核心幾何，繞組絕緣方法和技術有很大不同，比傳統(tǒng)變壓器的設計。一些令人關切的領域是：伏特 /反過來評級二次線，絕緣層層評級，絕緣材料損耗因數(shù)，繞組幾何，因為它關注的是寄生電容和 次級 漏磁，浸漬絕緣漆，以纏繞層，電暈水平和幾乎所有其他常規(guī)的問題，如熱利潤率，以及總成本。 高電壓倍增電路負責整頓和乘法的高電壓互感器二次電壓。這些電路使用高壓二極管和電 容器在 “電荷泵 ”電壓倍增器的連接。與高電壓變壓器，高電壓倍增器設計需要特定的專門知識。此外，以整頓和乘法，高壓電路中使用的過濾器的輸出電壓，并在監(jiān)測電壓和電流反饋控制。輸出阻抗可能故意添加，以防止放電電流從電源的存儲電容。 這些高電壓絕緣部件通常是從地面水平，以防止電弧了。絕緣材料的差別很大，但是典型的材料是：空氣， SF6氣體，絕緣油，固體 膠囊型 （ RTV，環(huán)氧樹11 脂等）。 對于 一個可靠的高電壓設計 而言，絕緣材料的選擇和過程控制可能是最重要的方面 。 控制電路使所有的電源一起工作。電路的復雜性可從一個模擬 IC 到 大量 的集成電路，甚至一個微處理器控制和監(jiān)測的所有方面的高壓電源。但是，基本的要求，每個控制電路必須滿足是精確調節(jié)輸出電壓和電流 的負載，輸入功率，決定和命令的規(guī)定。這是最好的反饋控制回路。圖 2顯示了如何利用反饋信號來調節(jié)輸出的電壓 。常規(guī)調控電壓和電流可通過監(jiān)測輸出電壓和電流分別。這是比較理想的（參考） 輸出信號。差額（錯誤）之間的反饋和參考將導致改變逆變器控制裝置， 這將導致改變權力交付輸出電路。 圖 2 電源控制環(huán) 此外，電壓和電流調節(jié)，其他參數(shù)可精確調節(jié)?？刂戚敵龉β屎苋菀淄瓿闪薠Y=Z 功能 （ 即 VI=W），和 比較理想的輸出功率范圍。事實上，任何變量內發(fā)現(xiàn)歐姆定律可以調節(jié) （電阻，電壓，電流和功率）。此外，最終的工藝參數(shù)可調節(jié)的影響，如果他們的高壓電源（即涂料，流量等）。 三。高電壓調節(jié) 必須有一個規(guī)范的高電壓和 /或恒流對于大多數(shù)應用中，涉及靜電。變化的輸出電壓或電流可以直接影響最終結果，因此，必須充分理解為一種錯誤來源。在高壓電源器，用于項目所需輸出 電壓參數(shù) 可以消除的一個重大錯誤來源 是 使用高度穩(wěn)定的 集成電路。 典型規(guī)格優(yōu)于 5ppm/C是 常規(guī)的。同樣 模擬集成電路（運算放大器， 模數(shù)和數(shù)模轉換器，等等） 可以消除的一個重要錯誤來源 是 慎重 挑選你所使用 設備。 獨特的高電壓電 源還有一個部分，這將是穩(wěn)定的錯誤主要來源：高電壓反饋分壓器。正如圖 1，高電壓反饋分壓器由一個電阻分壓器網(wǎng)絡。這個網(wǎng)絡將 輸出電壓足夠 低的水平來處理的控制電路 的問題，穩(wěn)定在這個網(wǎng)絡結果從大阻力的反饋電阻。 阻 值 高于 100百萬歐姆的電阻是常見的 （這是為了降低功耗和減少電路的影響， 以及 溫度變化而 產(chǎn)生的自熱 ）。大阻力和高電壓等級，需要獨特的技術，12 具體到高電壓電阻器。獨特的高電壓電阻必須 “配對 ”，以低價值的電阻率跟蹤，以確保根據(jù)溫度變化 電壓，濕度和時間。 此外，高附加值的 電阻 的反饋網(wǎng)絡是指易感性非常低電流的干擾?？梢钥闯?，電流低至 110-9放大器將導致 “100ppm錯誤。因此，電暈電流的影響，必須認真加以考慮的設計，電阻和電阻反饋網(wǎng)絡。此外，由于許多電阻技術是基于核心或陶瓷基板，壓電效應，還必須考慮。它可以證明，振動高壓電源在運行期間將實施一個信號，相關的振動頻率，在輸出的電力。 四。高壓電源 需要的 輔助 功能 在許多應用中的高電壓，增加控制功能 是 可能需要的工具。電源設計者必須熟悉的靜電應用的最終用戶。通過了解應用， 電源設計人員可以把重要的職能，以造福于結束 進程。一個 高壓電源 典型功能是可以實現(xiàn) 一種 “電弧識別 ”的控制，如 圖 3 所示 。通常情況下，電流感應裝置，如電流互感器或電阻插入 “低壓側 ”的高電壓輸出電路。通常情況下，電弧電流等于： I=