本文選題：低壓直流電弧　切入點：磁流體動力學(xué)　出處：《沈陽工業(yè)大學(xué)》2017年碩士論文

【摘要】：低壓開關(guān)電器作為關(guān)鍵的配電設(shè)備之一,在開斷過程中不可避免地將會產(chǎn)生電弧。電弧在毫秒級時間、毫米級空間內(nèi)快速動態(tài)變化,從而影響電器的開斷能力。電弧衍生機(jī)理和發(fā)展規(guī)律是國內(nèi)外研究者們廣泛關(guān)注的研究熱點與難點,相比于交流電弧,由于直流電弧不存在電流自然過零點現(xiàn)象,其熄滅更加困難。合理設(shè)計接觸器觸頭結(jié)構(gòu),使之產(chǎn)生磁場有利觸頭開斷是公用技術(shù)。磁場對電弧作用形成磁吹有利于電弧熄滅已是不爭的事實,因此探索外磁場及其變化對直流電弧的影響及有利電弧熄滅意義重大。本文以電磁場數(shù)值計算為基礎(chǔ),建立外磁場及直流電弧數(shù)學(xué)模型,通過數(shù)值仿真分析為直流接觸器外加磁場裝置結(jié)構(gòu)設(shè)計提供指導(dǎo)和方案。通過對多種永磁材料的磁場分布進(jìn)行對比仿真分析,研究結(jié)果表明三維磁場計算中的電弧模型由于電導(dǎo)率差異而產(chǎn)生磁場分布不均勻的現(xiàn)象,這為選擇和設(shè)計合理的外加磁場發(fā)生裝置提供了理論支撐�；诖帕黧w動力學(xué)(MHD)理論建立了綜合電弧運(yùn)動特性和電弧機(jī)理的空氣電弧數(shù)學(xué)模型,分別對外磁場作用下電弧特性和電弧運(yùn)動特性仿真分析,探究不同外磁場對直流電弧影響的共性機(jī)理,研究電弧在外磁場作用下運(yùn)動特性的本質(zhì)規(guī)律。通過外磁場對電弧特性的調(diào)控,為研究不同外磁場作用下電弧特性和電弧運(yùn)動行為提供理論依據(jù)。為了進(jìn)一步驗證上述理論分析和仿真計算的正確性,搭建直流接觸器電弧開斷特性實驗平臺。利用高速攝像機(jī)對電弧開斷過程進(jìn)行圖像采集并進(jìn)行圖像處理,根據(jù)實驗圖像及數(shù)據(jù)分析歸納出不同磁場作用下的電弧形態(tài)及變化規(guī)律,結(jié)合仿真分析結(jié)果,研究外磁場對直流感性負(fù)載產(chǎn)生電弧的反向運(yùn)動現(xiàn)象,以及電弧的溫度、氣流場、受力及壓強(qiáng)場等特性,結(jié)果表明:有外磁場作用電弧電壓明顯升高,熄弧時間減少,有利于電弧的熄滅;橫向磁場作用可以縮短電弧隨機(jī)運(yùn)動時間,有助于電弧弧根運(yùn)動,提高趨勢性運(yùn)動速度,增大電弧偏移量;徑向磁場作用可使電弧溫度和電導(dǎo)率降低,導(dǎo)致電弧的等效電阻增大。
[Abstract]:As one of the key distribution equipments, the low-voltage switchgear will inevitably produce arc during the process of switching off. The arc changes rapidly in millisecond time and millimeter space. The mechanism and development law of arc derivation are the focus and difficulty of researchers at home and abroad. Compared with AC arc, DC arc does not exist natural zero-crossing phenomenon. It is more difficult to extinguish the contactor. It is a common technology to design the contactor contact structure reasonably and make it produce magnetic field favorable to break the contact. It is an indisputable fact that the magnetic field forms a magnetic blow to the effect of the arc in favor of the arc extinguishing. Therefore, it is of great significance to explore the influence of external magnetic field and its changes on DC arc and the beneficial arc extinguishing. Based on the numerical calculation of electromagnetic field, the mathematical model of external magnetic field and DC arc is established in this paper. The numerical simulation analysis is used to provide guidance and scheme for the structure design of DC contactor's external magnetic field device, and the magnetic field distribution of various permanent magnetic materials is compared and analyzed by simulation. The results show that the arc model in 3D magnetic field calculation has the phenomenon of uneven magnetic field distribution due to the difference of conductivity. This provides a theoretical support for the selection and design of a reasonable external magnetic field generator. Based on the MHD theory, a mathematical model of air arc is established, which integrates the characteristics of arc motion and the arc mechanism. The common mechanism of the influence of different external magnetic fields on DC arc is explored by simulation and analysis of arc characteristics and arc motion characteristics under the action of external magnetic field, respectively. The essential law of arc motion characteristics under the action of external magnetic field is studied. It provides a theoretical basis for the study of arc characteristics and arc motion behavior under different external magnetic fields, and further verifies the correctness of the above theoretical analysis and simulation calculation. The experiment platform of arc breaking characteristics of DC contactor is set up. The high speed video camera is used to collect and process the image of the arc breaking process. According to the analysis of experimental images and data, the arc shape and variation law under different magnetic fields are summarized. Combining with the results of simulation analysis, the reverse motion phenomenon of arc produced by external magnetic field to DC inductive load, as well as the arc temperature and airflow field, are studied. The results show that the arc voltage increases obviously and the arc extinguishing time decreases with the external magnetic field, and the transverse magnetic field can shorten the arc random motion time, which is helpful to the arc root movement. The radial magnetic field can decrease the arc temperature and conductivity and increase the equivalent resistance of the arc.
【學(xué)位授予單位】：沈陽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM572.1

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