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遼寧科技大學(xué)本科生畢業(yè)論文 第16頁(yè)
Digital Drive Crane Hoist Conversion
While working on the bridge of a crane, I remember feeling the intense heat of the speed reduction Resistors. I looked over the prints and tried to figure out how to reduce this energy loss. As I understood, heat is the product of energy lost (). I was new to crane maintenance in 1990 and, having an electrical/electronic background,
Crane panel manufacturers desired a novel method of crane control that combines new technology with some of the oldest. The new crane panel resulted in lower costs, increased productivity and reduced wear on components, as well as energy savings.
I believed new technology existed. Several of the newer devices needed alternating current input. SCRs, VFDs and PMWs were becoming common acronyms in newer plants. The possibility of upgrading our pre-existing 250 VDC distribution was cost-prohibitive, Various transistors could run DC, but not at the ampere demands we needed. With crane panel replacement under consideration, we challenged our panel suppliers to develop new crane control technology
Digital Hoist Conversion
Severstal North America Inc. is an integrated steel mill dating back to 1917, when Henry Ford built it to supply his Ford Motor Co. auto manufacturing enterprise. It was operated as Ford Steel Division ur~ti11982, when it became Rouge Steel Co. In 2004, OAt Severstal Steel purchased the assets of Rouge Industries and Rouge Steel.
Figure1.A digital drive controller was installed Figure2. Preliminary setup of DDC hoist panel
on this 135-ton-capacity slab-handling crane
The market price for steel was flat in the early part of the new millennium, forcing departmental groups to look for cost-saving improvements. One improvement was the installation of a new type of digital electronic control panel in 2003. This panel represented the introduction of DC electronic crane control to Rouge Steel and the largest duplex crane hoist controller (dual 200-hp) of its type in North America.
The original panels were built on a P&H 135-ton slab-handling crane having standard DC hoisting contactor controls. They were industrial and functional, designed to handle the loads of this crane in 1972. The loads are greater now with heavier slabs, runing the crane at maximum limits and higher production rates. This caused premature equipment failures and production down-time. With three aging cranes in this bay, maintenance costs were rising to new highs. Those involved in maintenance were finding that distributors and manufactures were downsizing or had gone out of business, making replacement parts costly or obsolete. The market drivers of today are forcing the change to newer technologies
Figure3. Digital panel installed on crane trolley deck Figure4.Prewired resistors reduced start-up time
A novel design approach was asked of the crane panel manufactures. They replied with a proposed partnership and an effort to add some of the newest technology to the oldest methods of crane controls. The result was high-current transistor switching with a 250 VDC input. The design was well-thought-out and included integrating the original motors, limits, switches and wiring. Now speeds are controlled by sending the motors only enough current to safely lift and lower the load. The motors are soft stopped (reverse plugged) before the brakes close. This saves wear on components, reduces costs and increases productivity. Without the need for reduction resistors, there is no energy wasted, maximizing the energy savings. The panel installation of the SY-4 crane was completed in 2003 and is still running. The results are smoother movements with little energy loss (heat).
The new panels were designed for installation on the trolley deck, as opposed to the bridge deck.. This aids in troubleshooting and reduces excessive wiring mainly at the weak point of the cable powertrack.. This allowed the time and ability to perform all setup work during mini-downturns without disabling the original hoist. The original panel was left in place as a backup, as failures could not be predicted. To date, the fail-safe panel has not been required.
The panels were pre-wired and pre-tested prior to crane installation, further reducing crane downtime. When the transfer day came, only the master switch, motors and limit leads needed to be rerouted to the new system. On-the-job tuning and monitoring were vital for the first couple of days. It was important to have crane operators involved for that “personal feel” and to obtain their buy-in to the project, to increase awareness and productivity. No-load and full-load current tests were run with great results.
An aded benefit to this control is the electrical current savings. Without reductin resistors for speed points, and with the added benefit of power produced when regenerative lowering, this single crane installation saves more than ＄25000 in electricity annually. This can be a very important consideration if substation power is near critical usage levels. The demand this system imposes is much less than a similar contactor system. With energy costs on the rise, this is a concern for every project considered. Figure 5 indicates an example of electrical current savings potential by comparing contactor panel loads(top) to digital drive loads(bottom).
How it works in the circuit is not unique. The insulated gate bipolar transistor(IGBT) takes the place of the contactors and acceleration resistors. As the master switch is selected for greater speed, the circuitry triggers the transistor at a frequency(pulse width modulated) that allows current to flow through the IGBT. The current circulates in the standard series armature and series field along with the series brake. The longer the input is turned on, the higher the output average voltage (Figure 6). The higher the voltage, the higher the horsepower produced. This system can provide high torque with low currents(heat) as the result of motor regenerative properties. High speed with no load can also be accomplished. Much of this could not be achieved with the original panels.
Figure5.Example of energy saved during lowering sequence.
The difference is noticed when the IGBT is in its off cycle(Figure 7). In this instance, the motor acts as a generator, producing circulating currents through the flyback diode and maintaining self-induced motor currents. This effect reduces ripple and provides current that was not provided by the original power source. The reduction of current loads on system feeders and hardware further adds to the total savings package.
The following items are important considerations when determining if this system will work with an application.
IGBTs are the newest part of the design that makes this panel work with 250 volts DC. They combine the advantages of the bipolar transistor(high voltage and current) with the advantages of the metal oxide semiconductor field effect transistor(MOSFET)(low power consumtion and high switching). IGBTs are semiconductors that combine a high voltage and high current bipolar junction transistor(BJT) with a low-power and fast-switching MOSFET. Consequently, IGBTs provide faster speeds and better drive and output characteristics than power transistors and offer higher current capabilities than equivalent high-powered transistors.
Figure6.Hoist current flow when the IGBT is on
Figure7.Hoist continuing motor current flow when the IGBT is off.
Heat sinking, including consideration of air temperature and air flow, is essential to the proper operation of any solid-state reply. It is necessary to rovide an effective means of removing heat from the IGBT. The importance of using a proper heat sink cannot be overstressed, since it directly affects the maximum usable load current and maximum allowable ambient temperature. Up to 90 percent of the problems with transistors are directly related to heat. Lack of attention to this detail can result in improper switching(lockup) or even total destruction of the IGBT. If the device ever reaches an internal temperature of 105℃, it will be permanently destroyed. One of the problems encountered at Severstal NA was program temperature cutbacks due to excessive heating. When electrical current cutback does not control the drive, it will stop on software limits. Transistors develop heat as a result of a forward voltage drop through the junction of the IGBT. Beyond this point, heat will cause a reduction(software cutback) of the load current that can be handled. If the demand is too great, the program is designed to shut down.
Care must be taken when mounting solid-state relays(SSRs) in a confined area. SSRs should be mounted on individual heat sinks whenever possible. SSRs should never be operated without proper heat sinking or in free air, as they will thermally self-destruct under load. A simple way to monitor temperature is to slip a thermocouple under a mounting screw. If the base temperature does not exceed 45℃, the SSR is operating at its optimal level. Remember that the heatsink removes the heat from the SSR and transfers that heat to the air in the electrical enclosure. In turn, this air must circulate and transfer its heat to the outside ambient. Vents and forced ventilation are good ways to accomplish this. Semiconductor fuses are the only reliable way to protect SSRs. They are also referred to as current-limiting fuses, providing extremely fast opening while restricting let-through current far below the fault current that could destroy the semiconductor. This type of fuse tends to be expensive, but cheap by comparison to the damage that could occur, providing a means of fully protecting SSRs against high current overloads. An fuse rating is useful in aiding in the proper design of SSR fusing. This rating is the benchmark for an SSR's ability to handle a shorted output condition. Devices such as circuit breakers and slow blowfuses cannot react quickly enough to protect the SSR in a shorted condition and are not recommended. Every SSR has an rating. The idea is to select a fuse matching the capability of the solid-state relay for the same duration.
Figure8.IGBT and components mounted on heat Figure9.External mounted fans removed IGBT heat
Figure10. Panel fans removed internal heat buildup Figure11. Semiconductor fuses provide the best protection for solid-state relays
Motor switching and dynamic loads, such as motors and solenoids, can create special problems for SSPs. High initial surge current is drawn because its star t-up impedance is usually very low. As a motor rotates, it develops a counter electromotive force (CEMF) that resists the flow of currenL This CEMF can also add to the applied line voltage and create over-voltage conditions during turn-off and regenerative times. It should be noted that over-voltage caused by inductive voltage doubling or CEMF from the motor cannot be effectively dealt with by adding voltage-transient suppressors. Suppressors such as metal oxide varistors (MOVs) are typically designed for brief high-voltage spikes and may be destroyed by sustained hlgh-energy conduction. Voltage dump resistors may be needed in extreme cases and should be engineered to meet a system's demand, It is therefore important that SSRa are chosen to withstand the highest expected sustained voltage.
Problems encountered while running the200-hp dual drive were few hut worth mentioning. The program allows for setdng many variables (i.e., speed, currents, brake-open voltage). Most of these are detrimental to the drive or motor if set incorrectly. Although staying within the drive specifications is safe, this may not produce the desired actions. Ambient temperatures must also be considered, since most useful application are near higher-temperature areas. Following are several problems(and solutions) observed during installation and trials:
l Problem 1:The first problem presented itself when applying excessive brake-open curent. The direction contactors were flashed and pitted. Also, the emergency brake contactor appears bluish from high heat. Reducing brake-open current and power-on time to a shorter duration solved the problem.
l Problem 2:Hall effect transistors and IGBT were thought to be faulty parts and/or wiring, but this could not be duplicated. Many suspect parts were replaced, but it was determined that internal panel ambient temperature was the problem. This was solved with cooling fans on the doors and on the IGBT cooling fins.
l Problem 3:Temperature cutbacks usually led to errors. It was found that a new crane operator did not like operating the hoist at full speed. Longer run time and higher IGBT cycles caused unnecessary heating in panels. Reducing field current settings eased this problem. This increased the lowering speeds but greatly reduced the IGBT voltage drop, in turn reducing its heat dissipation. Cooling fans eliminated the problem.
l Problem 4:All power must be disconnected from the line because all lines feed from a common bus capacitive filtering system. This means that the typical way of “pulling motor disconnect and running the controls only” to troubleshoot does not work. The panel diagnostics and troubleshooting information provided is very helpful.
l Problem 5:Lack of electronic knowledge by the electricians is a concern. When production downtime is critical, the time to troubleshoot is a high-priced commodity. This ultimately puts pressure on the electricians, causing frustration. The solutions was to ensure that the crew is involved Mth project design and installation. Training is vital. If the maintenance team is nat up to speed with the technology, failure is probable. Two training classes were held for all electrical team members.
After one year, the actual materials maintenance and labor savings were calculated, with a payback of 6.2 months. Cost savings and efficiency gains were greater than expected. This led the way to the next drive conversion, which was scheduled for 2006. With a cooperative effort by salespersons, manufacturers, engineers and end-users, Severstal NA vastly improved its ability to compete successfully.
Acknowledgments
The author would like to acknowledge the efforts of former general supervisor Fred Schwartz and the crew at Severstal North America. Without their help, the project may never have gotten this far.
References
1. Creech, R., 'Energy Savings -- DC Digital and DC Contactor Hoist Control System," Iron ~ Steel Technotogg, May 2005, pp. 225-228.
2. http://ray.eeel.nist.gov/modval/database/contents/reports/igbt.html
3. http://web.ece.umr.edu/computing/unix/software/matlab/toolbox/powersys/igbt.html
4. http://www.fujisemiconductor.com/old_pdf/app_ notes/r_ipm.pdf
5. http://www.mathworks.com/access/helpdesk_r13/help/toolbox/physmod/powersys/igbt.html
數(shù)字機(jī)起重機(jī)提升轉(zhuǎn)換
雖然工作在橋上的吊車(chē)，我記得感覺(jué)酷熱的速度減少電阻.我看著圖紙，并試圖弄清楚如何減少這種能源損失.正如我的理解一樣，熱是產(chǎn)品的能源損失（ ） 。我是新來(lái)起重機(jī)維修工于1990年，并在電氣/電子背景下，我認(rèn)為新技術(shù)是存在的.一些較新的設(shè)備需要交流電輸送.在新工廠(chǎng)，SCRs ， VFDs andPMWs已成為常用縮寫(xiě)詞。在新的可能性下，提升我們的預(yù)先分配現(xiàn)有的250伏直流電是成本過(guò)高.各種晶體管可以運(yùn)行直流，但不能以安培的要求，.現(xiàn)在起重機(jī)小組正在考慮向我們的面板供應(yīng)商提出制定新的起重機(jī)控制技術(shù)。
起重機(jī)面板制造商設(shè)計(jì)了一個(gè)新的起重機(jī)控制方法，那就是把新技術(shù)和最老的技術(shù)結(jié)合起來(lái)。這個(gè)新的起重機(jī)面板導(dǎo)致了降低成本，提高生產(chǎn)力和減少磨損的部件，以及節(jié)約能源的效果。
數(shù)字提升轉(zhuǎn)換
韋爾北美公司是一家綜合鋼廠(chǎng)可以追溯到1917年，當(dāng)亨利福特建立它提供了福特汽車(chē)公司生產(chǎn)企業(yè). 在1982年之前，這是作為福特鋼司，之后改名為高棉鋼公司。在2004年，俄羅斯謝韋爾鋼收購(gòu)了高棉鋼鐵工業(yè)和高棉鋼公司。
在新的千年年初，鋼鐵的市場(chǎng)價(jià)格持平，迫使部門(mén)團(tuán)體尋求節(jié)省成本的改進(jìn)。在2003年，一個(gè)改進(jìn)的方法是安裝一種新型的數(shù)字式電子控制面板，這個(gè)小組代表介紹，在北美，直流電子起重機(jī)控制高棉最大的鋼鐵和全雙工起重機(jī)吊重機(jī)控制器（雙200馬力）的類(lèi)型。
圖1.數(shù)字硬盤(pán)控制器被安裝在這臺(tái)有 圖2.初步安裝DDC的提升小組
135噸板坯處理能力的起重機(jī)上
原來(lái)的面板上建立了一個(gè)P&H公司135噸板坯處理起重機(jī)在吊裝標(biāo)準(zhǔn)直流接觸器控制。它們的工業(yè)功能被設(shè)計(jì)用于處理負(fù)載的這臺(tái)于1972生產(chǎn)的起重機(jī)。在保證最高限額和更高的生產(chǎn)速度之下，運(yùn)行起重機(jī)的負(fù)載更大了就好比加了巨大的石板。這就造成早產(chǎn)和生產(chǎn)設(shè)備故障停機(jī)時(shí)間加大。三老化起重機(jī)在這灣，維修費(fèi)用上升到新高。那些參與維修的人發(fā)現(xiàn)，分銷(xiāo)商和制造商縮編或已停業(yè)，使備件昂貴或過(guò)時(shí)。市場(chǎng)驅(qū)動(dòng)的今天，迫使改變新技術(shù)。
起重機(jī)面板制造商被要求需要一種新的設(shè)計(jì)方法。他們回應(yīng)在最基本的起重機(jī)控制上努力增加一些最新的技術(shù)。其結(jié)果是高電流晶體管開(kāi)關(guān)的250伏直流電輸入。設(shè)計(jì)是經(jīng)過(guò)深思熟慮的，其中包括整合原汽車(chē)，限制，交換機(jī)和擰?，F(xiàn)在速度控制發(fā)送只夠目前的汽車(chē)安全升降機(jī)及降低負(fù)荷。電機(jī)軟停止（反向插入）前剎車(chē)密切。這樣可以節(jié)省的磨損部件，降低成本和提高生產(chǎn)效率。而不需要減少電阻，沒(méi)有能源浪費(fèi)，最大限度地節(jié)約能源。小組安裝系統(tǒng)- 4起重機(jī)于2003年完成，目前仍在運(yùn)行。結(jié)果表明，幾乎沒(méi)有順暢流動(dòng)的能量損失（熱）。
圖3.數(shù)字面板安裝在起重機(jī)小車(chē)甲板上 圖4.預(yù)置電阻減少啟動(dòng)時(shí)間
新的面板設(shè)計(jì)為安裝在甲板上的小車(chē)，而不是橋面。這個(gè)故障排除和減少過(guò)多的電線(xiàn)主要是在于電纜的薄弱。在稍微衰退而停用原來(lái)的起重機(jī)，在這允許的時(shí)間和能力內(nèi)來(lái)執(zhí)行所有的安裝工作。原來(lái)的面板留在地方作為備用，失敗是無(wú)法預(yù)測(cè)的。迄今為止，面板沒(méi)有達(dá)到萬(wàn)無(wú)一失要求。
該小組的前有線(xiàn)和預(yù)先測(cè)試前，起重機(jī)安裝，進(jìn)一步降低起重機(jī)停機(jī)。當(dāng)一天的轉(zhuǎn)讓中，只有總開(kāi)關(guān)，汽車(chē)和限制導(dǎo)致需要轉(zhuǎn)移至新系統(tǒng)。在職調(diào)整和監(jiān)測(cè)至關(guān)重要的第一幾天。這是非常重要的吊機(jī)操作員參與的“個(gè)人感覺(jué)” ，并獲得他們的買(mǎi)進(jìn)該項(xiàng)目，以提高認(rèn)識(shí)和生產(chǎn)力。空載和滿(mǎn)負(fù)荷運(yùn)行試驗(yàn)，目前取得極大的結(jié)果。
一個(gè)附加的好處是這個(gè)控制電流儲(chǔ)蓄。沒(méi)有電阻減少的速度點(diǎn)和再生降低時(shí)，功率產(chǎn)生的附加的好處，這種單一的起重機(jī)安裝每年節(jié)省超過(guò)25000美元的電費(fèi)。這是一個(gè)非常重要的事情是附近變電站電力使用水平的關(guān)鍵。在實(shí)行這一制度的需求遠(yuǎn)低于類(lèi)似的聯(lián)系人制度。隨著能源成本上升，圖5顯示的一個(gè)例子電流儲(chǔ)蓄潛力比較接觸小組負(fù)載（頂部）到數(shù)字驅(qū)動(dòng)負(fù)載（下）。
如何運(yùn)作的電路并不是獨(dú)一無(wú)二的。絕緣柵雙極晶體管（ IGBT ）取代電流接觸器和加速度電阻。作為主開(kāi)關(guān)是選擇更大的速度，晶體管電路觸發(fā)的頻率（ 脈寬調(diào)制） ，使電流流過(guò)IGBT的。目前流通中的標(biāo)準(zhǔn)系列電樞和一系列領(lǐng)域隨著一系列制動(dòng)。投入的時(shí)間越長(zhǎng)，，輸出更高的平均電壓（圖6 ） 。高的電壓保證高馬力生產(chǎn)。此系統(tǒng)可以提供高扭矩，低電流（熱）由于電機(jī)再生的緣故。高速無(wú)負(fù)載時(shí)也可以完成。這在很大程度上是不可能實(shí)現(xiàn)的在原來(lái)的面板上。
圖5.節(jié)省能源降低序列
所不同的是發(fā)現(xiàn)時(shí)的IGBT是在其起飛周期（圖7 ） 。在這種情況下，電機(jī)作為發(fā)電機(jī)，產(chǎn)生循環(huán)電流通過(guò)反激式二極管和維護(hù)自誘導(dǎo)電動(dòng)機(jī)電流。這種效應(yīng)降低了紋波，并規(guī)定這是目前所無(wú)法提供的原始動(dòng)力源。減少電流負(fù)載饋線(xiàn)系統(tǒng)和硬件進(jìn)一步增加了總儲(chǔ)蓄封裝。
下列項(xiàng)目是重要的考慮因素當(dāng)確定是否該系統(tǒng)將與應(yīng)用程序一起運(yùn)作。
IGBT是最新的部分設(shè)計(jì)，使得面板在250伏特直流下工作。他們結(jié)合了雙極型晶體管（高電壓和電流）的優(yōu)勢(shì)，金屬氧化物半導(dǎo)體場(chǎng)效應(yīng)晶體管（ MOSFET ）的電源（低功耗和高開(kāi)關(guān)） 。 IGBT是半導(dǎo)體，結(jié)合高電壓和高電流雙極型晶體管（雙極晶體管）的低功耗和快速開(kāi)關(guān)的MOSFET 。因此， IGBT提供更快的速度和更好的驅(qū)動(dòng)器和輸出特性比功率晶體管，并提供更高的電流能力比同等高功率晶體管。
圖6.IGBT開(kāi)啟時(shí)提升了電流
散熱，包括考慮空氣溫度和空氣流通，是必不可少的正常運(yùn)作的任何固態(tài)繼電器。有必要提供一種有效的手段，消除熱的IGBT 。必要時(shí)，使用適當(dāng)?shù)纳崞膊贿^(guò)分，因?yàn)樗苯佑绊懽畲罂捎秘?fù)載電流和最高允許環(huán)境溫度。高達(dá)百分之九十的問(wèn)題晶體管是直接相關(guān)的熱量。沒(méi)有注意這個(gè)細(xì)節(jié)可能會(huì)導(dǎo)致不適當(dāng)?shù)拈_(kāi)關(guān)（鎖定） ，甚至完全破壞IGBT 。如果該設(shè)備以往的內(nèi)部溫度達(dá)到105攝氏度 ，這將是永久摧毀。一個(gè)韋爾北美公司遇到的問(wèn)題，那是程序溫度在降低由于過(guò)度的熱量。當(dāng)電流減少到不能控制驅(qū)動(dòng)器，它將會(huì)停止對(duì)軟件的限制。晶體管開(kāi)發(fā)熱而導(dǎo)致的正向壓降通過(guò)路口的IGBT。除了這一點(diǎn)，將導(dǎo)致熱量減少（軟件削減）的負(fù)載電流可處理。如果需求過(guò)大，該計(jì)劃旨在關(guān)閉。
圖7.IGBT關(guān)閉時(shí)電機(jī)電流在繼續(xù)提升
當(dāng)安裝固態(tài)繼電器（序列）在一個(gè)封閉的地區(qū)時(shí)，應(yīng)當(dāng)十分小心。只要有可能，固態(tài)繼電器應(yīng)安裝在單獨(dú)的散熱片上。序列不應(yīng)該沒(méi)有適當(dāng)?shù)牟僮骰蛏嶙杂煽諝猓驗(yàn)樗鼈儗⒃谶@個(gè)負(fù)荷下自毀。一個(gè)簡(jiǎn)單的方法來(lái)監(jiān)測(cè)溫度就是將在熱電偶下安裝螺釘。如果基溫度不超過(guò)45攝氏度，是操作系統(tǒng)的SSR在其最佳水平。請(qǐng)記住，移除SSR的熱量和轉(zhuǎn)讓熱空氣中的電器附件。反過(guò)來(lái)，這必須空氣流通和轉(zhuǎn)讓其熱量到外面。噴口和強(qiáng)制通風(fēng)良好這一途徑來(lái)實(shí)現(xiàn)這個(gè)目標(biāo)。
圖8. IGBT和元件安裝在散熱片上 圖9.在IGBT的外部安裝風(fēng)扇散熱
半導(dǎo)體引信是唯一可靠的方式來(lái)保護(hù)序列。他們也被稱(chēng)為限流熔斷器，提供極快的開(kāi)放，同時(shí)限制讓通過(guò)遠(yuǎn)低于目前的故障電流，可以摧毀半導(dǎo)體。這種類(lèi)型的導(dǎo)火索往往是昂貴的，但比較便宜的損害可能發(fā)生，提供了一個(gè)手段，充分保護(hù)序列對(duì)高電流超載。一個(gè)保險(xiǎn)絲評(píng)價(jià)是有用的幫助在適當(dāng)?shù)脑O(shè)計(jì)，SSR的能力是處理短路輸出條件。設(shè)備，如斷路器和熔斷器緩慢打擊不能作出迅速反應(yīng)，足以保護(hù)SSR在短路條件和不推薦。每一個(gè)SSR有一個(gè)類(lèi)別。這樣做是為了選擇一個(gè)引信匹配的能力，固態(tài)繼電器的同一時(shí)間。
電機(jī)開(kāi)關(guān)和動(dòng)態(tài)載荷，如汽車(chē)和螺線(xiàn)管，可以建立特殊問(wèn)題的序列。要注意高初始浪涌電流，因?yàn)樗膯?dòng)阻抗通常很低。作為電機(jī)轉(zhuǎn)動(dòng)時(shí)，它開(kāi)發(fā)了一個(gè)反電動(dòng)勢(shì)（ CEMF ）來(lái)抵制流動(dòng)的電流。這CEMF也可以添加到線(xiàn)電壓的應(yīng)用，并創(chuàng)造過(guò)電壓條件在關(guān)閉和再生次。應(yīng)當(dāng)指出的是，過(guò)電壓引起的感應(yīng)電壓一倍或CEMF從電機(jī)不能得到有效處理，增加電壓瞬態(tài)抑制器。抑制器，如金屬氧化物變阻器（ MOVs ）通常是專(zhuān)為簡(jiǎn)短的高電壓尖峰，并可能被摧毀的持續(xù)高能量傳導(dǎo)。電壓轉(zhuǎn)儲(chǔ)電阻可能需要在極端的情況下，應(yīng)設(shè)計(jì)，以滿(mǎn)足系統(tǒng)的需求。因此，重要的是序列中選出能承受的最高預(yù)期持續(xù)的電壓。
圖10.面板風(fēng)扇散去內(nèi)部熱量積聚 圖11.安森美半導(dǎo)體提供最好的熔斷器保護(hù)固態(tài)繼電器
遇到的問(wèn)題，同時(shí)運(yùn)行的200馬力的雙驅(qū)動(dòng)器很少，但值得一提。該計(jì)劃允許設(shè)置許多變量（即，速度，電流，制動(dòng)初始電壓） 。大多數(shù)這些不利于驅(qū)動(dòng)器或電機(jī)如果設(shè)置不正確。雖然留在驅(qū)動(dòng)器的規(guī)格是安全的，這可能不會(huì)產(chǎn)生預(yù)期的行動(dòng)。環(huán)境溫度也必須加以考慮，因?yàn)樽钣杏玫膽?yīng)用是近高溫度區(qū)。以下是幾個(gè)問(wèn)題（和解決方案）觀(guān)察在安裝過(guò)程中和試驗(yàn)：
(1)第一個(gè)問(wèn)題出現(xiàn)當(dāng)提出過(guò)度制動(dòng)初始電流。接觸了方向閃現(xiàn)和進(jìn)站。此外，緊急制動(dòng)接觸出現(xiàn)高熱量。減少制動(dòng)初始電流和功率上的時(shí)間更短的時(shí)間解決了這個(gè)問(wèn)題。
(2)霍爾效應(yīng)晶體管和IGBT被認(rèn)為是錯(cuò)誤的部分和/或線(xiàn)路系統(tǒng)，但這無(wú)法復(fù)制的。許多人懷疑部分取代，但它的內(nèi)部面板確定，環(huán)境溫度是這個(gè)問(wèn)題。這是解決散熱風(fēng)扇的入口和IGBT的散熱片的方法。
(3)溫度削減通常導(dǎo)致錯(cuò)誤。結(jié)果發(fā)現(xiàn)，一個(gè)新的起重機(jī)操作員不喜歡經(jīng)營(yíng)提升全速。長(zhǎng)遠(yuǎn)來(lái)說(shuō)，時(shí)間和更高的IGBT周期中造成不必要的加熱板。減少外地當(dāng)前設(shè)置來(lái)緩解這一問(wèn)題。這增加了降低速度，但大大降低了IGBT的電壓下降，反過(guò)來(lái)又減少其散熱。冷卻風(fēng)扇來(lái)消除這個(gè)問(wèn)題。
(4)一切功能必須同線(xiàn)路分開(kāi)，因?yàn)樗芯€(xiàn)路由一個(gè)共同的電容過(guò)濾系統(tǒng)提供。這意味著，典型的方式“拉電機(jī)斷開(kāi)和運(yùn)行控制只有”排查不工作。該小組的診斷和故障排除提供的信息是非常有幫助的。
(5)缺乏電子知識(shí)的電工是一個(gè)關(guān)切的問(wèn)題。當(dāng)生產(chǎn)停工是至關(guān)重要的，解決的時(shí)間是一個(gè)高價(jià)位的商品。這最終對(duì)電工造成壓力，造成挫折。該解決方案是確保工作人員是參與項(xiàng)目的設(shè)計(jì)和安裝的工作中。培訓(xùn)是至關(guān)重要的。如果維修人員不是提高維修技術(shù)的速度，失敗是有可能的。兩個(gè)所有電氣團(tuán)隊(duì)成員的培訓(xùn)班被成立了。
一年后，維修的實(shí)際材料和勞動(dòng)力節(jié)省了計(jì)算，回收期為6.2個(gè)月。節(jié)約成本和提高效率大于預(yù)期。這導(dǎo)致了下一個(gè)驅(qū)動(dòng)器轉(zhuǎn)換，這是定于2006年。與合作努力的銷(xiāo)售商，制造商，工程師和終端用戶(hù)， 韋爾北美公司那大大改善其競(jìng)爭(zhēng)能力為競(jìng)爭(zhēng)成功。
致謝
作者要感謝前總務(wù)主管弗雷德施瓦茲和韋爾北美公司全體工作人員的努力。沒(méi)有他們的幫助，該項(xiàng)目可能永遠(yuǎn)不會(huì)走到這么遠(yuǎn)的地步。
參考資料
1 克里奇，河， “節(jié)能---直流數(shù)字和直流接觸器提升機(jī)控制系統(tǒng)， ”鋼鐵學(xué)院， 2005年5月， 225-228頁(yè)。
2 http://ray.eeel.nist.gov/modval/database/contents/reports/igbt.html
3 http://web.ece.umr.edu/computing/unix/software/matlab/toolbox/powersys/igbt.html
4 http://www.fujisemiconductor.com/old_pdf/app_notes/r_ipm.pdf
5 http://www.mathworks.com/access/helpdesk_r13/help/toolbox/physmod/powersys/igbt.html