【作者】 王宇鹏；

【导师】 任碧莹； 陈桂涛； 马保慧；

【作者基本信息】 西安理工大学 ， 电气工程（专业学位）， 2021， 硕士

【摘要】 微弧氧化(Micro-arc Oxidation,MAO)是一种在电解液中采用脉冲电源实现轻金属表面改性的处理技术。由于脉冲电参数对微弧氧化负载加工效果至关重要,因此深入研究微弧氧化的负载需求,优化电源控制已成为进一步提升该技术的主要研究方向。本文针对微弧氧化负载等效模型与参数辨识、特殊的脉冲波形发生及脉冲控制策略等问题展开研究。首先,为了从电气负载角度探究微弧氧化工艺条件下氧化膜层的生长过程,本文建立微弧氧化负载等效模型,选取微弧氧化在不同反应阶段的相关实验数据,利用带遗忘因子的递推最小二乘法(Forgetting Factor Recursive Least Squares,FFRLS)对模型参数进行辨识,基于辨识参数拟合得到的负载端电压与实际测量的负载端电压具有一致性,验证了负载等效模型的正确性及参数辨识方法的准确性。进而根据加入负脉冲后的负载波形变化规律,分析得到一阶纯阻负载等效模型,并对相关参数求解。基于模型参数辨识结果,总结了参数变化规律,讨论了氧化膜层生长过程和模型参数之间的内在关系,为电源设计提供理论指导依据。其次,依据负载等效模型,分析了微弧氧化反应与脉冲形式的关系,得到电流型非对称多电平的脉冲需求。为实现该种形式的脉冲,深入研究了一种Buck+Full bridge脉冲输出变换器,阐述变换器实现脉冲输出的工作过程。为满足脉冲电流快速响应条件及电流低纹波需求,采用交错并联型Buck电路,分析并推导了输出电流的纹波表达式。针对微弧氧化反应过程中存在的负载大范围频繁波动和输出电流突变问题,研究了一种应用于该变换器的预测电流控制方法。其中,引入两步预测以补偿数字控制器存在的一拍延时。同时,分析了电感参数失配条件下预测电流控制策略的鲁棒性。最后,为了验证脉冲变换器拓扑及控制策略的分析,搭建了脉冲变换器仿真模型,并设计了系统硬件电路和软件程序,搭建了实验平台。仿真和实验结果表明,Buck+Fullbridge脉冲输出变换器可以输出幅值、占空比和极性均可独立调节的电流型非对称多电平脉冲,能够满足不同微弧氧化负载脉冲需求。两步预测电流控制在多种突变工况下能够使输出电流脉冲快速达到期望值,提高了脉冲输出变换器的动态性能及抗干扰性。更多还原

【Abstract】 Micro-arc oxidation(MAO)technology is a treatment technology that uses pulsed power in the electrolyte to modify the surface of light metals.Since the pulse electrical parameters are very important to the processing effect of the micro-arc oxidation load,in-depth study of the demand of the micro-arc oxidation power supply and optimizing the power control have become the main research direction to further improve the technology.This paper focuses on the research of load equivalent model of MAO,parameter identification,the generation of special pulse waveform and pulse control strategy.Firstly,in order to explore the growth process of the oxide film under the conditions of the micro-arc oxidation process from the perspective of electrical load,In this paper,the equivalent load model of micro-arc oxidation is established,and the experimental data of micro-arc oxidation in different reaction stages are selected,the Forgetting Factor Recursive Least Squares(FFRLS)algorithm is used to identify the model parameters,and the load terminal voltage obtained by the identification parameter fitting is consistent with the actual measured load terminal voltage.The correctness of the load equivalent model and the accuracy of the parameter identification method are verified.Furthermore,according to the change rule of the load waveform after adding the negative pulse,the equivalent model of the first-order pure resistance load is analyzed and the relevant parameters are solved.Based on the results of model parameter identification,the parameter change rule is summarized,and the internal relationship between the growth process of oxidation film and model parameters is discussed,which provides theoretical guidance for power supply design.Secondly,according to the load equivalent model,the relationship between the micro-arc oxidation reaction and the pulse form is analyzed,and the pulse demand of current-type asymmetric multi-level is obtained.In order to realize this kind of pulse,a kind of pulse converter which with Buck+Full bridge is deeply studied,the working process of the converter periodically realizing pulse output is described.In order to meet the requirements of fast response of pulse current and low ripple current,an interleaved parallel Buck circuit is used,and the ripple expression of output current is analyzed and deduced.Aiming at the problems of large-range frequent fluctuations in load and sudden changes in output current during micro-arc oxidation reaction,a predictive current control method applied to the converter is studied.And aiming at the one-beat delay problem of the digital controller,a two-step prediction is introduced to compensate the predictive current control.Meanwhile the robustness of the predictive current control strategy under the condition of inductance parameter mismatch is analyzed.Finally,in order to verify the analysis of the pulse converter topology and control strategy,a pulse converter simulation model was built,and the system hardware circuit and software program were designed,and an experiment platform was built.The result of Simulation and experimental show that the pulse output converter can achieve asymmetric multi-level pulse output with independent adjustments of pulse amplitude,duty cycle and polarity,and can meet the needs of different micro-arc oxidation load pulses.The designed two-step predictive current control can make the output current pulse reach the expected value quickly under various abrupt conditions,and improve the dynamic performance and anti-interference of the pulse output converter.更多还原