本安开关变换器输出短路火花放电机理与引燃能力及可控抑爆方法研究

The output short-circuit spark discharge of intrinsically safe switching converter is the main factor to ignite explosive gas. However, due to lack of clear understanding about the mechanism and ignition capability of the output short-circuit spark discharge, the unreasonable anti-explosive measures and evaluating methods have to be adopted to hinder the advancement and application of the high-power intrinsically safe switching converters. To solve these problems, the mechanism and ignition capability of the output short-circuit spark discharge are studied based on the programmable micro-nano gap discharge experiment platform and programmable ignition experiment apparatus. The mathematical model describing the output short-circuit spark discharge characteristics is established, and the relationship among the spark discharge power and time with the electrical and component parameters is analyzed, respectively. The parameters combination which can make spark discharge power the highest is searched. The mathematical model describing the ignition capability of the output short-circuit spark discharge is established, the relationship among the minimum ignition power with time and the electrical and component parameters is obtained, respectively. The critical conditions to take explosion-proof measures are obtained by comparing the maximum spark discharge power with the minimum ignition power. The controllable explosion-proof method to realize intrinsically safe anti-explosive through controlling the spark discharge power and sustaining time is proposed. According to the obtained explosion-proof method, the pulse power criterion to evaluate intrinsically safe performance of the switching converter is achieved. The relationship among the pulse power and intrinsically safe output power with the electrical and component parameters is analyzed, respectively. The design method of high power intrinsically safe switching converter is concluded. The obtained research achievements can help to promote the development and application of high-power intrinsically safe switching converters.

本安开关变换器输出短路火花放电是引燃爆炸性气体的主要因素，但由于尚未对短路火花放电机理及引燃能力有明晰认识，以致采用不合理的抑爆措施和评价方法，严重妨碍大功率本安开关变换器的发展及应用。为此，本项目拟采用程控微纳间隙放电实验平台及程控引燃试验装置对开关变换器的输出短路火花放电机理及引燃能力进行研究，建立描述其短路火花放电特性的数学模型，分析火花放电功率及时间与电气元件参数的关系，寻求使得火花放电功率最大的参数组合；建立描述短路火花放电引燃能力的数学模型，得出最小引燃功率与时间及电气元件参数的关系；将最大火花放电功率与最小引燃功率进行比较得出采取抑爆措施的临界条件；提出通过控制火花放电功率及持续时间实现本安防爆的可控抑爆方法，得出评价本安性能的脉冲功率判据；分析脉冲功率及本安输出功率与电气元件参数之间的关系，综合得出大功率本安开关变换器的设计方法，促进大功率本安开关变换器的应用与推广。

针对对本安开关变换器的短路等故障火花放电机理及引燃能力认识不够，以致采用不合理的抑爆措施，严重妨碍大功率本安变换器的发展和应用的问题，本项目对故障火花与电弧放电机理、引燃能力、脉冲功率判据、可控抑爆方法及优化设计理论进行了研究，具体工作及取得的进展如下：.通过建立基于IEC安全火花试验装置电极的PIC-MCC数学模型，并进行数值计算分析，揭示了开关变换器短路火花放电机理：真空环境通过场致发射诱发热电子发射，形成热-场火花放电；介质环境同时存在热-场火花放电和汤姆逊放电。通过研究CH4-N2气体、甲烷浓度等对放电特性的影响，揭示了CH4-N2气体电离放电机理，为研究火花放电引燃能力奠定了基础。.根据变换器输出短路放电机理，并综合考虑温度、电离系数、极间电压等参数，推导得出了火花放电电阻和功率的解析式，以及电极消耗能量、储能元件残存能量及有效点燃能量；通过分析电极分断速度与放电时间的影响及分断初始电流、电弧电压等参数，推导出可描述电感分断放电引燃能力的临界引燃功率与能量，实现了火花与电弧放电引燃能力的定量描述。.通过对输出短路放电特性及有效引燃能量进行分析，得出了有效短路火花功率的表达式；依据容性电路的临界点燃曲线及其短路放电特性，得出了给定输入电压对应的临界引燃功率；将二者进行比较得出了本安开关变换器的脉冲功率判据。依据脉冲功率判据及临界引燃能量，得出了通过控制火花放电时间实现本安防爆的可控抑爆方法，据此可有效提高变换器的本安输出功率。.综合考虑本安和电气性能要求，定义了本安开关变换器的最大输出功率并得出其与输入和输出电压、负载电阻及工作频率之间的四维关系图；考虑到电容ESR对本安及电气性能的影响，以及所得出的脉冲功率判据和等效电感，分别提出了基于最大输出功率、脉冲功率判据、等效电感及考虑电容ESR影响的本安开关变换器设计方法。项目研究取得的进展和结论对促进大功率本安开关变换器的开发及推广应用具有重要理论意义和实用价值。

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