【摘要】：機場助航燈是保障飛機在特殊環(huán)境下安全起降的必要目視助航設(shè)施。為了保障機場助航燈的正常運行,需要實時監(jiān)測燈光回路的絕緣狀況是否良好。因此對助航燈光電纜回路絕緣電阻實時在線監(jiān)測單元的研究與設(shè)計具有重要意義。但是目前現(xiàn)有的絕緣電阻在線監(jiān)測方法存在一些缺陷,無法達到實時在線準確監(jiān)測絕緣電阻的目的。本文首先介紹了國內(nèi)外絕緣電阻在線監(jiān)測研究現(xiàn)狀和現(xiàn)有的方法,從理論上論證了其局限性和缺陷。針對其主要的缺陷,提出了一種新型助航燈光電纜回路絕緣電阻實時在線監(jiān)測單元的設(shè)計方案,主要有三點:用24V低壓直流激勵電源,代替現(xiàn)有的高壓電源,減小電纜承壓;采用開關(guān)切換方法,分時采樣交流單獨作用和交直流共同作用狀況下的采樣電流,抵消掉因交流高電壓產(chǎn)生的干擾影響;采用磁隔離高頻交流調(diào)制與解調(diào)技術(shù),提高隔離等級,保障電路安全。本文詳細地從理論上驗證了新方法的可行性。首先,構(gòu)建了燈光回路絕緣電阻等效模型。接著,對比現(xiàn)有方案中的缺陷,一一分析了新方案的優(yōu)勢與可行性。最后,分別列舉了幾種不同工況下本設(shè)計測量結(jié)果的可靠性。在硬件電路設(shè)計方面,本文采用推挽式變換器為本設(shè)計提供磁隔離保護;詳細地介紹了推挽式變壓器的工作原理,重點介紹了推挽變壓器的設(shè)計過程。在控制方面,本文采用AT89C51單片機作為智能數(shù)據(jù)處理控制芯片。在此基礎(chǔ)上設(shè)計了配套的數(shù)據(jù)采集、轉(zhuǎn)換、處理以及通訊傳輸電路。實現(xiàn)了將燈光電纜回路絕緣電阻實時在線監(jiān)測的功能。在軟件設(shè)計方面,本文從初始化子程序,定時子程序,絕緣電阻計算子程序以及基于MODBUS的通訊中斷子程序幾個方面,具體地介紹了主程序及各個子程序的運行過程,并給出了具體軟件流程圖。絕緣電阻實時在線監(jiān)控單元采集測量電路中的電流信號,在CPU中對采樣信號進行分析與計算,得到實時的絕緣電阻值,之后通過MODBUS通訊網(wǎng)絡(luò)將絕緣電阻阻值傳送給上位機并記錄,具有可追溯性,方便及時發(fā)現(xiàn)各種問題。
[Abstract]:The airport navigation aid lamp is the necessary visual navigation aid facility to ensure the aircraft to take off and land safely under the special environment. In order to ensure the normal operation of the airport navigation light, it is necessary to monitor whether the insulation condition of the lamp loop is good in real time. Therefore, it is of great significance to research and design the real-time on-line monitoring unit of insulation resistance in navigation light cable circuit. However, the existing on-line monitoring methods of insulation resistance have some defects, which can not achieve the purpose of real-time and accurate on-line monitoring of insulation resistance. This paper first introduces the present situation and existing methods of on-line monitoring of insulation resistance at home and abroad, and theoretically demonstrates its limitations and defects. In view of its main defects, a new design scheme of real-time on-line monitoring unit of insulation resistance in navigation light cable circuit is proposed. There are three main points: 24V low-voltage DC excitation power supply is used to replace the existing high-voltage power supply, and the cable voltage is reduced; The switching method is adopted, the sampling current under the condition of time-sharing sampling AC single action and AC / DC interaction is used to counteract the interference caused by high AC voltage. The magnetic isolation high frequency AC modulation and demodulation technology is adopted to improve the isolation level and ensure the security of the circuit. The feasibility of the new method is verified in detail in this paper. Firstly, the equivalent model of insulation resistance in lighting circuit is constructed. Then, the advantages and feasibility of the new scheme are analyzed by comparing the shortcomings of the existing schemes. Finally, the reliability of the design results under different working conditions is listed respectively. In the aspect of hardware circuit design, this paper adopts push-pull converter to provide magnetic isolation protection for the design, introduces the working principle of push-pull transformer in detail, and emphatically introduces the design process of push-pull transformer. In the aspect of control, AT89C51 microcontroller is used as intelligent data processing control chip. On this basis, a complete set of data acquisition, conversion, processing and communication transmission circuit is designed. The function of real-time on-line monitoring of insulation resistance of lighting cable circuit is realized. In the aspect of software design, this paper introduces the main program and the running process of each subroutine in detail from the aspects of initialization subroutine, timing subroutine, insulation resistance calculation subroutine and communication interrupt subroutine based on MODBUS. The software flow chart is given. The insulation resistance real-time on-line monitoring unit collects the current signal in the measuring circuit, analyzes and calculates the sampling signal in CPU, and obtains the real time insulation resistance value. Then the insulation resistance value is transmitted to the host computer and recorded through MODBUS communication network, which has traceability and convenience to find all kinds of problems in time.
【學(xué)位授予單位】：大連交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：V351.3;TM934.31

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本文編號：2370752