For optimal design of constant stress accelerated life test（CSALT） with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT desig...For optimal design of constant stress accelerated life test（CSALT） with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-I censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method, The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions.展开更多
为进一步提高中点电压钳制(neutral point clamped,NPC)H桥级联五电平逆变器的动态响应、降低控制器计算负担的同时确保装置低损耗运行,文中在电压矢量矩形区域分类的基础上,提出一种以满足动态响应和降低开关损耗为目标的两级优化模型...为进一步提高中点电压钳制(neutral point clamped,NPC)H桥级联五电平逆变器的动态响应、降低控制器计算负担的同时确保装置低损耗运行,文中在电压矢量矩形区域分类的基础上,提出一种以满足动态响应和降低开关损耗为目标的两级优化模型预测电压控制策略。首先根据逆变器数学模型和期望电流进行目标电压矢量计算、修正,接着基于矩形区域分类对目标电压矢量进行定位;并以定位后的候选矢量为基础,设计了两级优化目标函数以输出满足要求的最优矢量。仿真和实验结果验证了该方法的有效性,与空间矢量脉宽调制以及传统模型预测电流、电压控制策略相比,该文所研究的两级优化模型预测电压控制策略,在确保逆变器动态响应的前提下既能降低控制器计算负担,还能有效减少器件开关损耗。展开更多
基金supported by National Natural Science Foundation of China(Grant Nos. 50935002, 51075370, 51105341)National Hi-tech Research and Development Program of China(863 Program, Grant No. 2007AA04Z409)+1 种基金the Technology Foundation of National Defense ProgramZhejiang Provincial Natural Science Foundation of China (Grant Nos. Y1100777, Y1080762)
文摘For optimal design of constant stress accelerated life test（CSALT） with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-I censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method, The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions.
文摘为进一步提高中点电压钳制(neutral point clamped,NPC)H桥级联五电平逆变器的动态响应、降低控制器计算负担的同时确保装置低损耗运行,文中在电压矢量矩形区域分类的基础上,提出一种以满足动态响应和降低开关损耗为目标的两级优化模型预测电压控制策略。首先根据逆变器数学模型和期望电流进行目标电压矢量计算、修正,接着基于矩形区域分类对目标电压矢量进行定位;并以定位后的候选矢量为基础,设计了两级优化目标函数以输出满足要求的最优矢量。仿真和实验结果验证了该方法的有效性,与空间矢量脉宽调制以及传统模型预测电流、电压控制策略相比,该文所研究的两级优化模型预测电压控制策略,在确保逆变器动态响应的前提下既能降低控制器计算负担,还能有效减少器件开关损耗。
