發(fā)布時間：2018-02-23 05:20

  本文關(guān)鍵詞： 醫(yī)用X光機(jī)電源 BoostAPFC 全橋逆變LLC諧振變換器 軟開關(guān)技術(shù) PFM控制 單周期控制　出處：《重慶大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：X射線的發(fā)現(xiàn)對人類醫(yī)學(xué)史的進(jìn)步做出了巨大貢獻(xiàn)，X射線被廣泛應(yīng)用于疾病的診斷與治療。X射線的質(zhì)量決定了成像質(zhì)量并影響著人體健康，而X光機(jī)電源系統(tǒng)的質(zhì)量決定了X射線的質(zhì)量，因此研究高性能的X光機(jī)電源系統(tǒng)具有現(xiàn)實(shí)意義。目前的X光機(jī)電源的不足主要體現(xiàn)在：頻率低，體積大，效率低，輸出電壓上升時間長，紋波大，將嚴(yán)重影響X射線的質(zhì)量，增加X射線對病人的傷害。 針對目前X光機(jī)電源的現(xiàn)狀以及存在的問題，本文對X光機(jī)電源系統(tǒng)的高壓直流電源和燈絲電源分別進(jìn)行了設(shè)計，對電源系統(tǒng)進(jìn)行了理論分析與相關(guān)公式推導(dǎo)，通過Saber仿真軟件進(jìn)行了仿真驗證，搭建了實(shí)驗平臺進(jìn)行了實(shí)驗驗證，仿真、實(shí)驗結(jié)果與理論分析吻合，達(dá)到了預(yù)期效果。 本文首先闡述了醫(yī)用X光機(jī)電源的發(fā)展現(xiàn)狀及存在的不足，以及電源系統(tǒng)對X射線質(zhì)量的影響，對成像質(zhì)量的重要意義。本文將全橋逆變LLC諧振軟開關(guān)技術(shù)應(yīng)用于X光機(jī)電源系統(tǒng)中。諧振軟開關(guān)能夠提高工作頻率，減小電源體積，有利于電源系統(tǒng)的小型化；并且解決了因高頻化而帶來的開關(guān)損耗大的問題，提高了整體效率。對全橋逆變LLC諧振變換器進(jìn)行了理論分析，建立了基波等效模型，推導(dǎo)了增益公式，畫出增益曲線并進(jìn)行分析，對諧振元件的參數(shù)進(jìn)行了詳細(xì)設(shè)計。 采用PFM控制方式，通過調(diào)節(jié)開關(guān)頻率來調(diào)節(jié)諧振槽的增益，從而實(shí)現(xiàn)輸出電壓在40kV~120kV之間的調(diào)節(jié)，比傳統(tǒng)Buck加全橋逆變電路控制方式更為簡單。設(shè)計了以MC33067芯片為核心的PFM控制電路，以及采樣電路，保護(hù)電路。 采用單周期控制無源無損軟開關(guān)BoostAPFC電路，詳細(xì)分析了單周期控原理及無源無損軟開關(guān)電路，并對PFC主電路參數(shù)進(jìn)行了詳細(xì)設(shè)計。介紹了單周期控制芯片IR1150，并設(shè)計了以其為核心的控制電路。計算出PFC級的開環(huán)傳遞函數(shù)，畫出其bode圖進(jìn)行穩(wěn)定性分析。 根據(jù)燈絲電源只需對燈絲加熱提供足夠的功率，而對電流波形沒有嚴(yán)格要求的特點(diǎn)，在充分利用變壓器漏感及隔離電容等參數(shù)的基礎(chǔ)上，設(shè)計了基于LC串聯(lián)諧振并采用PFM控制方式的燈絲電源。 最后利用Saber仿真軟件及實(shí)驗進(jìn)行了驗證，仿真及實(shí)驗結(jié)果表明，本文設(shè)計的醫(yī)用X光機(jī)電源系統(tǒng)基本達(dá)到了預(yù)期效果，，能夠滿足設(shè)計要求。
[Abstract]:The discovery of X-ray has made a great contribution to the progress of human medical history. X-ray is widely used in the diagnosis and treatment of diseases. The quality of X-ray determines the quality of imaging and affects human health. The quality of the power supply system of X-ray machine determines the quality of X-ray, so it is of practical significance to study the high performance power supply system of X-ray machine. At present, the shortcomings of the power supply of X-ray machine are mainly reflected in: low frequency, large volume, low efficiency. The long rise time of output voltage and the large ripple will seriously affect the quality of X-ray and increase the injury of X-ray to the patient. Aiming at the present situation and existing problems of X-ray machine power supply, this paper designs the high voltage DC power supply and filament power supply of X-ray machine power supply system, and analyses the power supply system theoretically and deduces the relevant formula. Saber simulation software is used to verify the simulation. The experimental platform is built and the simulation results are consistent with the theoretical analysis, and the expected results are achieved. In this paper, the current situation and shortcomings of the power supply for medical X-ray machine are described, and the influence of the power system on the quality of X-ray is also discussed in this paper. In this paper, the full-bridge inverter LLC resonant soft switch technology is applied to the X-ray machine power supply system. The resonant soft switch can increase the working frequency, reduce the power supply volume, and is conducive to the miniaturization of the power supply system. The problem of high switching loss caused by high frequency is solved, and the overall efficiency is improved. The theoretical analysis of full-bridge inverter LLC resonant converter is carried out, the equivalent fundamental wave model is established, and the gain formula is derived. The gain curve is drawn and analyzed, and the parameters of the resonant element are designed in detail. The output voltage is adjusted between 40 kV and 120 kV by adjusting the switching frequency to adjust the gain of the resonant slot by using the PFM control mode. Compared with the traditional Buck and full-bridge inverter circuit, the control circuit of PFM based on MC33067 chip, sampling circuit and protection circuit are designed. The single cycle control passive lossless soft switching BoostAPFC circuit is used to analyze the single cycle control principle and passive lossless soft switch circuit in detail. The main circuit parameters of PFC are designed in detail. The single cycle control chip IR1150 is introduced, and the control circuit based on IR1150 is designed. The open loop transfer function of PFC level is calculated and its bode diagram is drawn for stability analysis. According to the characteristic that the filament power supply only need to provide enough power to the filament heating, and there is no strict requirement for the current waveform, on the basis of making full use of the parameters such as transformer leakage inductance and isolation capacitance, A filament power supply based on LC series resonance and PFM control is designed. Finally, the Saber simulation software and experimental results show that the power supply system of the medical X-ray machine designed in this paper has basically achieved the desired results, and can meet the design requirements.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM46

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本文編號：1526219