【作者】 余琼；

【导师】 王淑娟；

【作者基本信息】 哈尔滨工业大学 ， 电力电子与电力传动， 2011， 博士

【摘要】 航天继电器是国防武器系统和航天型号不可缺少的关键元器件,主要完成系统配电、信号传递、电路隔离及负载切换等功能。航天继电器可靠性寿命试验是产品出厂前必做的一项抽样试验。现行的试验方法只监测触点压降和开路电压,获取的信息有限,很难分析产品的退化过程和失效机理,无法评价不同试验条件和产品结构对继电器可靠性的影响,对指导产品可靠性设计、加速产品可靠性增长贡献有限。为全面分析和评价航天继电器可靠性,本文提出一种基于性能退化的航天继电器可靠性寿命试验方法。通过分析寿命试验过程中的航天继电器多个退化参数,在分析接触失效机理的基础上,对航天继电器退化轨迹建模、寿命预测和可靠性评估方法进行了深入研究。目前航天继电器失效机理分析往往采用事后分析法,通用性不强,易发生软失效漏判。本文提出一种基于退化参数的航天继电器接触失效模式和失效机理判别方法。该方法通过分析继电器的超程时间、弹跳时间、燃弧时间等多个参数的变化规律,检测时间参数异常、持续燃弧、弹跳时间过高等触点软失效;采用主元分析和距离判别分析方法从退化参数中提取触点间隙的变化特征,实现继电器触点断开和粘接等硬失效机理的分类和判别。失效触点表面形态和化学成分分析结果证明了该方法的有效性。通过深入剖析产品失效物理、化学规律建立其退化模型已成为产品可靠性预计的主要方法。本文采用Fisher判别准则确定了航天继电器的接触性能退化敏感预测变量。提出了基于小波变换和平稳时间序列分析的预测变量预处理方法,减少预测变量的干扰信号对模型精度的影响。采用累积损伤理论建立了航天继电器失效物理退化模型。该模型充分考虑了燃弧能量、产品结构、触点材料属性以及样品分散性对触点间隙退化的影响。采用回归分析方法对继电器失效物理退化模型参数进行估计。利用所建模型进行航天继电器寿命预测,其平均预测精度达到70%以上。现有可靠性评估方法假定继电器失效率恒定,分布类型为指数分布,并不符合产品的真实情况。本文提出基于模糊综合评判的航天继电器最佳失效分布类型确定方法。通过分析继电器触点失效机理,提出基于失效统计模型和基于随机过程的航天继电器退化失效可靠性评估方法。根据建立的多维退化参数统计模型,分别对发生不同失效机理的样品进行了可靠性评估,其可靠度与实际值误差小于5%。最后,本文设计并实现了航天继电器可靠性评价及寿命试验系统。采用集散控制方式设计基于CAN总线的同步、高速、多通道、多样品的继电器动态波形采集单元,根据采集的波形数据设计并实现退化参数计算的软件算法。采用VC++与Matlab混合编程方法完成上位机软件编写,实现失效机理判别、退化轨迹建模、寿命预测及可靠性评估等方法。本研究充分利用航天继电器的退化参数对其可靠性进行全面分析和评价,相关方法也可推广应用到其他类似结构的开关电器中。更多还原

【Abstract】 Space relays are the indispensable key components used in defense weapon systems and aerospace products for completing power distribution, signal transmission, circuit isolation and load switching. Life test for space relays is a compulsory sampling test before the products go out. Generally, contact voltage drop and open-circuit voltage are observed during the current life test. Because the information obtained from the two parameters is too limited, it is difficult to further reveal the degradation process and failure mechanisms of the products, and it is hard to describe the influences of different test conditions and product structures on the reliability of the relays. These disadvantages result in the inapplicability of the current life test for guiding product design and accelerating product reliability growth.To comprehensively analyze and evaluate the reliability of space relays, a new reliability life test method for space relays based on performance degradation is proposed in this paper. Based on the analysis of failure mechanisms, the modeling degradation trace, life prediction and reliability assessment methods of space relays are extensively investigated by analyzing the variations of several parameters recorded during life test.Currently, post-analysis method is applied to analyze the failure mechanisms of space relays, which is lack of generality and easy to overlook soft failures. A method for discriminating contact failure modes and failure mechanisms based on degradation parameters is proposed in this paper. Many kinds of contact soft failures, such as abnormal time parameters, sustained arcing and excessive rebound duration, are detected by analyzing the variations of several degradation parameters including overtravel time, rebound duration, closing time, etc. The principal component analysis method and distance discriminant analysis method are adopted to extract variations of contact gap from these degradation parameters. After that, the classification and discrimination of contact failure mechanisms of hard failures are accomplished. The surface morphologies and chemical compositions of the failure contacts are also analyzed, and the results indicate the discriminant methods used in this paper are valid.Degradation trace modeling method based on the thorough analysis of failure physical and chemical law has become a main reliability prediction method of products. The Fisher discriminant criterion is employed to determine prediction variables that are very sensitive to contact performance degradation of space relays. Furthermore, a preprocessing method based on wavelet transform and stationary time series analysis is introduced to reduce the impact of interference of the prediction variables on the accuracy of the model. To fully consider the influence of arcing energy, product structure, contact material and sample dispersion on degradation of contact gap, the physical-of-failure degradation model of space relays is established according to cumulative damage theory. The parameters of the model are estimated by regression analysis method and the average prediction accuracy of this model is up to 70%.The current reliability assessment method of space relays assumes the product distribution is subject to exponential distribution which means a constant failure rate at any time. However, the assumption is not very reasonable. Consequently, a fuzzy comprehensive evaluation method is introduced to determine the most appropriate distribution type. With the consideration of the contact failure mechanisms, the reliability assessment methods for degradation failure of space relays are proposed based on failure statistical model and stochastic process. Then the assessment of various samples in different failure mechanism is realized according to the multi-parameters statistical model, and the error between the assessment results and the practical reliability value is less than 5%.Finally, a reliability evaluation and life test system for space relays is designed and accomplished in this paper. A synchronous, high-speed, multi-channel, multi-sample dynamic waveform acquisition unit is developed based on CAN-bus.According to the waveform data of the tested relays, the software algorithms for calculating each degradation parameter are designed and implemented. The PC software is developed to carry out these methods including failure mechanism discrimination, degradation trace modeling, life prediction and reliability assessment of space relays.The degradation parameters are fully utilized for analyzing the reliability of space relays, and the proposed methods also can be applied to other switching devices with similar structures.更多还原