本文選題：電子膨脹閥 + 建模仿真��； 參考：《山東科技大學》2011年碩士論文

【摘要】：電子膨脹閥(EEV)是制冷系統(tǒng)中的節(jié)流元件,它在系統(tǒng)中的主要作用是調(diào)節(jié)系統(tǒng)制冷劑流量、節(jié)流降壓及控制過熱度。深入全面了解電子膨脹閥流量輸出響應(yīng)特性、電子膨脹閥的開度-流量控制調(diào)節(jié)特性,對于合理設(shè)計電子膨脹閥流量與開度控制規(guī)律,獲得熱泵空調(diào)系統(tǒng)良好的運行品質(zhì)具有重要的學術(shù)與工程指導意義。 本文在探討電子膨脹閥數(shù)字控制特征的基礎(chǔ)上,建立了電子膨脹閥控制系統(tǒng)的數(shù)學模型,據(jù)此搭建了電子膨脹閥數(shù)字控制仿真實驗平臺,并進行計算機數(shù)字仿真分析。揭示了電子膨脹閥數(shù)字控制系統(tǒng)開度與流量特性；通過系統(tǒng)仿真分析獲得電子膨脹閥的流量負反饋控制的穩(wěn)態(tài)響應(yīng)特性與間隙特性對系統(tǒng)穩(wěn)態(tài)輸出的影響規(guī)律。通過實驗測試驗證了本文所建數(shù)學模型的合理性。 在電子膨脹閥數(shù)字控制系統(tǒng)中,引入PID控制算法,建立了含PID調(diào)節(jié)器的控制系統(tǒng)數(shù)學模型,并對控制系統(tǒng)的輸出穩(wěn)態(tài)特性與常規(guī)系統(tǒng)進行比較分析。仿真結(jié)果表明：PID調(diào)節(jié)系統(tǒng)相比于常規(guī)控制系統(tǒng)能夠縮短系統(tǒng)響應(yīng)時間,降低系統(tǒng)開機響應(yīng)波動性并抑制系統(tǒng)超調(diào)現(xiàn)象。 為深入分析電子膨脹閥流量特性,搭建了基于PLC控制步進電機,實現(xiàn)閥口開度數(shù)字調(diào)節(jié)的流量-開度測試系統(tǒng)。設(shè)計了具有過載保護與短路保護的步進電機驅(qū)動電路,采用PLC直接驅(qū)動步進電機驅(qū)動方式與四相八拍控制方式,實現(xiàn)對電子膨脹閥開度的精確控制。采用FS4000質(zhì)量流量傳感器、HITEK壓力變送器以及PT100鉑電阻分別測量系統(tǒng)管路中氣體流量、壓力、溫度等物理量,設(shè)計了電壓信號與電流信號采集電路與PT100電阻測量電路,實現(xiàn)對系統(tǒng)各參數(shù)的測量。 計算機輔助測試(CAT)實驗系統(tǒng)的軟件設(shè)計主要包括PLC梯形圖程序設(shè)計與工業(yè)組態(tài)軟件世紀星監(jiān)控界面設(shè)計。PLC控制程序?qū)崿F(xiàn)對04AD模塊與04PT模塊傳感器測量數(shù)據(jù)采集,實現(xiàn)對步進電機轉(zhuǎn)速、轉(zhuǎn)向的逐個脈沖輸出的數(shù)字控制。監(jiān)控界面設(shè)計了系統(tǒng)工作主界面,實時模擬電子膨脹閥的工作現(xiàn)場,控制并記錄電子膨脹閥的開度脈沖數(shù),實時顯示系統(tǒng)中各個物理參數(shù)狀態(tài)。設(shè)計了數(shù)據(jù)采集、實時曲線、歷史曲線等多種測試輔助界面,采集與處理傳感器的信號數(shù)據(jù),記錄分析實驗測試數(shù)據(jù),增強流量測試實驗的功能性與可實驗性。 本文通過仿真與實驗對比研究電子膨脹閥的流量特性,改善變頻空調(diào)系統(tǒng)中蒸發(fā)器的熱負荷匹配,實現(xiàn)對一拖多制冷機組的制冷劑流量分配,改善制冷系統(tǒng)的整機性能,提高能源利用率,降低能耗,促進制冷技術(shù)的不斷向前發(fā)展和創(chuàng)新。CAT系統(tǒng)的多功能與可視化功能,為研究電子膨脹閥的流量特性提供一條新的途徑。系統(tǒng)同時具有監(jiān)測與控制功能,對于制冷系統(tǒng)控制技術(shù)的發(fā)展有著重要的指導意義。
[Abstract]:Electronic expansion valve (EEV) is a throttle element in the refrigeration system. Its main function in the system is to regulate the refrigerant flow, throttling the pressure and controlling the superheat. Deeply and comprehensively understand the response characteristics of the electronic expansion valve flow output, the opening and flow control regulation characteristics of the electronic expansion valve, and the reasonable design of the electronic expansion valve flow and opening control law, It is of great academic and engineering significance to obtain good operation quality of heat pump air-conditioning system. Based on the discussion of the digital control characteristics of the electronic expansion valve, the mathematical model of the electronic expansion valve control system is established in this paper. According to this model, the simulation experiment platform of the electronic expansion valve digital control is built, and the computer digital simulation analysis is carried out. The open and flow characteristics of digital control system of electronic expansion valve are revealed, and the steady state response characteristics and clearance characteristics of negative feedback control of electronic expansion valve are obtained by system simulation. The rationality of the mathematical model is verified by experiment. In the digital control system of electronic expansion valve, the mathematical model of control system with PID regulator is established by introducing PID control algorithm, and the output steady state characteristic of the control system is compared with that of the conventional system. The simulation results show that compared with the conventional control system, the response time of the system can be shortened, the response volatility of the system can be reduced and the overshoot phenomenon can be restrained. In order to deeply analyze the flow characteristics of electronic expansion valve, a flow-opening testing system based on PLC is built to realize digital adjustment of valve opening. The stepper motor drive circuit with overload protection and short circuit protection is designed. The PLC direct drive stepper motor driving mode and the four phase eight beat control mode are adopted to realize the accurate control of the opening degree of the electronic expansion valve. By using FS4000 mass flow sensor HITEK pressure transmitter and PT100 platinum resistance to measure the physical quantities of gas flow, pressure and temperature in the system respectively, a voltage signal and current signal acquisition circuit and a PT100 resistor measuring circuit are designed. The measurement of system parameters is realized. The software design of CAT-based computer aided testing (CAT) experiment system mainly includes PLC ladder diagram program design and industrial configuration software century star monitor interface design. PLC control program realizes the data acquisition of 04AD module and 04PT module sensor. Realize the digital control of step motor speed and steering pulse output one by one. The main interface of the system is designed to simulate the working field of the electronic expansion valve in real time. The opening pulse number of the electronic expansion valve is controlled and recorded. The physical parameters of the system are displayed in real time. The data acquisition, real-time curve and history curve are designed to collect and process the signal data of the sensor, to record and analyze the experimental test data, and to enhance the function and experimentability of the flow test experiment. In this paper, the flow characteristics of electronic expansion valve are studied by comparing simulation and experiment, the heat load matching of evaporator in frequency conversion air conditioning system is improved, the refrigerant flow distribution is realized for one towing and multiple refrigeration units, and the whole performance of refrigeration system is improved. To improve energy efficiency, reduce energy consumption, promote the continuous development of refrigeration technology and innovate the multi-function and visual function of cat system, which provides a new way to study the flow characteristics of electronic expansion valve. The system has the function of monitoring and controlling at the same time, which has important guiding significance for the development of refrigeration system control technology.
【學位授予單位】：山東科技大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：TH134

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